Blood-based cardiometabolic phenotypes in atrial fibrillation and their associated risk: EAST-AFNET 4 biomolecule study

BACKGROUND

Atrial fibrillation (AF) and concomitant cardiometabolic disease processes interact and combine to lead to adverse events such as stroke, heart failure, myocardial infarction, and cardiovascular death. Circulating biomolecules provide quantifiable proxies for cardiometabolic disease processes. Their role in defining subphenotypes of AF is not known.

METHODS AND RESULTS

This prespecified analysis of the EAST-AFNET4 biomolecule study assigned patients to clusters using polytomous variable latent class analysis (poLCA) based on baseline concentrations of thirteen precisely-quantified biomolecules potentially reflecting ageing, cardiac fibrosis, metabolic dysfunction, oxidative stress, cardiac load, endothelial dysfunction, and inflammation. In each cluster, rates of cardiovascular death, stroke, or hospitalization for heart failure or acute coronary syndrome, the primary outcome of EAST-AFNET 4, were calculated and compared between clusters over median 5.1 years follow-up. Findings were independently validated in a prospective cohort of 748 patients with AF (BBC-AF; median follow up 2.9 years).Unsupervised biomolecule analysis assigned 1586 patients (71 years old, 46% women) into four clusters. The highest-risk cluster was dominated by elevated BMP10, IGFBP7, NT-proBNP, ANGPT2 and GDF15. Patients in the lowest-risk cluster showed low concentrations of these biomolecules. Two intermediate-risk clusters differed by high or low concentrations of hsCRP, IL-6, and D-dimer. Patients in the highest-risk cluster had a 5-fold higher cardiovascular event rate than patients in the low-risk cluster. Early rhythm control was effective across clusters (pinteraction = 0.63). Sensitivity analyses and external validation in BBC-AF replicated clusters and risk gradients.

CONCLUSIONS

Biomolecule concentrations identify cardiometabolic subphenotypes in patients with atrial fibrillation at high and low cardiovascular risk.

Circulating BMP10 Levels Associate With Late Postoperative Atrial Fibrillation and Left Atrial Endomysial Fibrosis

BACKGROUND

Serum bone morphogenetic protein 10 (BMP10) blood levels are a marker for history of atrial fibrillation (AF) and for major adverse cardiovascular events in patients with AF, including stroke, AF recurrences after catheter ablations, and mortality. The predictive value of BMP10 in patients undergoing cardiac surgery and association with morphologic properties of atrial tissues are unknown.

OBJECTIVES

This study sought to study the correlation between BMP10 levels and preoperative clinical traits, occurrence of early and late postoperative atrial fibrillation (POAF), and atrial fibrosis in patients undergoing cardiac surgery.

METHODS

Patients with and without preoperative AF history undergoing first cardiac surgery were included (RACE V, n = 147). Preoperative blood biomarkers were analyzed, left (n = 114) and right (n = 125) atrial appendage biopsy specimens were histologically investigated after WGA staining, and postoperative rhythm was monitored continuously with implantable loop recorders (n = 133, 2.5 years).

RESULTS

Adjusted multinomial logistic regression indicated that BMP10 accurately reflected a history of persistent AF (OR: 1.24, 95% CI: 1.10-1.40, P = 0.001), similar to NT-pro-BNP. BMP10 levels were associated with increased late POAF90 occurrence after adjustment for age, sex, AF history, and early POAF occurrence (HR: 1.07 [per 0.1 ng/mL increase], 95% CI: 1.00-1.14, P = 0.041). Left atrial endomysial fibrosis (standardized β = 0.22, P = 0.041) but not overall fibrosis (standardized Β = 0.12, P = 0.261) correlated with circulating BMP10 after adjustment for age, sex, AF history, reduced LVF, and valvular surgery indication.

CONCLUSIONS

Increased BMP10 levels were associated with persistent AF history, increased late POAF incidence, and LAA endomysial fibrosis in a diverse sample of patients undergoing cardiac surgery.

Longer and better lives for patients with atrial fibrillation: the 9th AFNET/EHRA consensus conference

AIMS

Recent trial data demonstrate beneficial effects of active rhythm management in patients with atrial fibrillation (AF) and support the concept that a low arrhythmia burden is associated with a low risk of AF-related complications. The aim of this document is to summarize the key outcomes of the 9th AFNET/EHRA Consensus Conference of the Atrial Fibrillation NETwork (AFNET) and the European Heart Rhythm Association (EHRA).

METHODS AND RESULTS

Eighty-three international experts met in Münster for 2 days in September 2023. Key findings are as follows: (i) Active rhythm management should be part of the default initial treatment for all suitable patients with AF. (ii) Patients with device-detected AF have a low burden of AF and a low risk of stroke. Anticoagulation prevents some strokes and also increases major but non-lethal bleeding. (iii) More research is needed to improve stroke risk prediction in patients with AF, especially in those with a low AF burden. Biomolecules, genetics, and imaging can support this. (iv) The presence of AF should trigger systematic workup and comprehensive treatment of concomitant cardiovascular conditions. (v) Machine learning algorithms have been used to improve detection or likely development of AF. Cooperation between clinicians and data scientists is needed to leverage the potential of data science applications for patients with AF.

CONCLUSIONS

Patients with AF and a low arrhythmia burden have a lower risk of stroke and other cardiovascular events than those with a high arrhythmia burden. Combining active rhythm control, anticoagulation, rate control, and therapy of concomitant cardiovascular conditions can improve the lives of patients with AF.

Anticoagulation with edoxaban in patients with long atrial high-rate episodes ≥24 h

BACKGROUND AND AIMS

Patients with long atrial high-rate episodes (AHREs) ≥24 h and stroke risk factors are often treated with anticoagulation for stroke prevention. Anticoagulation has never been compared with no anticoagulation in these patients.

METHODS

This secondary pre-specified analysis of the Non-vitamin K antagonist Oral anticoagulants in patients with Atrial High-rate episodes (NOAH-AFNET 6) trial examined interactions between AHRE duration at baseline and anticoagulation with edoxaban compared with placebo in patients with AHRE and stroke risk factors. The primary efficacy outcome was a composite of stroke, systemic embolism, or cardiovascular death. The safety outcome was a composite of major bleeding and death. Key secondary outcomes were components of these outcomes and electrocardiogram (ECG)-diagnosed atrial fibrillation.

RESULTS

Median follow-up of 2389 patients with core lab-verified AHRE was 1.8 years. AHRE ≥24 h were present at baseline in 259/2389 patients (11%, 78 ± 7 years old, 28% women, CHA2DS2-VASc 4). Clinical characteristics were not different from patients with shorter AHRE. The primary outcome occurred in 9/132 patients with AHRE ≥24 h (4.3%/patient-year, 2 strokes) treated with anticoagulation and in 14/127 patients treated with placebo (6.9%/patient-year, 2 strokes). Atrial high-rate episode duration did not interact with the efficacy (P-interaction = .65) or safety (P-interaction = .98) of anticoagulation. Analyses including AHRE as a continuous parameter confirmed this. Patients with AHRE ≥24 h developed more ECG-diagnosed atrial fibrillation (17.0%/patient-year) than patients with shorter AHRE (8.2%/patient-year; P < .001).

CONCLUSIONS

This hypothesis-generating analysis does not find an interaction between AHRE duration and anticoagulation therapy in patients with device-detected AHRE and stroke risk factors. Further research is needed to identify patients with long AHRE at high stroke risk.

Disturbed atrial metabolism, shear stress, and cardiac load contribute to atrial fibrillation after ablation: AXAFA biomolecule study

AIMS

Different disease processes can combine to cause atrial fibrillation (AF). Their contribution to recurrent AF after ablation in patients is not known. Cardiovascular processes associated with recurrent AF after AF ablation were determined by quantifying biomolecules related to inflammation, metabolism, proliferation, fibrosis, shear stress, atrial pressure, and others in the AXAFA biomolecule study.

METHODS AND RESULTS

Twelve circulating cardiovascular biomolecules (ANGPT2, BMP10, CA125, hsCRP, ESM1, FABP3, FGF23, GDF15, IGFBP7, IL6, NT-proBNP, and hsTnT) were quantified in plasma samples obtained prior to a first AF ablation using high-throughput, high-precision assays. Cox regression was used to identify biomolecules associated with recurrent AF during the first 3 months after AF ablation. In 433 patients (64 years [58, 70]; 33% women), baseline concentrations of ANGPT2, BMP10, hsCRP, FGF23, FABP3, GDF15, and NT-proBNP were elevated in patients with recurrent AF (120/433; 28%). After adjustment for 11 clinical features and randomized treatment, elevated NT-proBNP [hazard ratio (HR) 1.58, 95% confidence interval (1.29, 1.94)], ANGPT2 [HR 1.37, (1.12, 1.67)], and BMP10 [HR 1.24 (1.02, 1.51)] remained associated with recurrent AF. Concentrations of ANGPT2, BMP10, and NT-proBNP decreased in patients who remained arrhythmia free, but not in patients with recurrent AF, highlighting their connection to AF. The other eight biomarkers showed unchanged concentrations.

CONCLUSION

Elevated concentrations of ANGPT2, BMP10, and NT-proBNP are associated with recurrent AF after a first AF ablation, suggesting that processes linked to disturbed cardiomyocyte metabolism, altered atrial shear stress, and increased load contribute to AF after AF ablation in patients.

Women have less progression of paroxysmal atrial fibrillation: data from the RACE V study

BACKGROUND

Sex differences in atrial fibrillation (AF) are observed in terms of comorbidities, symptoms, therapies received, AF progression and cardiovascular complications.

METHODS

We assessed the differences in prevalence and the determinants of AF progression, as well as the clinical characteristics and quality of life (QoL), between women and men with paroxysmal AF included in the RACE V (Reappraisal of Atrial Fibrillation: Interaction between hyperCoagulability, Electrical remodeling, and Vascular Destabilisation in the Progression of AF) study. At baseline, extensive phenotyping was done. To assess AF progression, implantable loop recorder (ILR) monitoring was used throughout follow-up. AF progression was defined as (1) progression to persistent or permanent AF or (2) progression of paroxysmal AF (>3% burden increase).

RESULTS

417 patients were included, 179 (43%) of whom were women. Women were older (median 67 years vs 63 years, p<0.001), less often had coronary artery disease (n=11 (6%) vs n=36 (16%), p=0.003), had more obesity (n=57 (32%) vs n=50 (21%), p=0.013), had less epicardial and pericardial fat (median 144 (interquartile range [IQR] 94-191) mL vs 199 (IQR 146-248) mL, p<0.001; and median 89 (ICQ 61-121) mL vs 105 (IQR 83-133) mL, p<0.001, respectively) and had more impaired left atrial function. The median follow-up was 2.2 (1.6-2.8) years. 51 of 417 patients (5.5% per year) showed AF progression (15/179 (8.4%) women and 36/238 (15.1%) men, p=0.032). Multivariable analysis showed tissue factor pathway inhibitor, N-terminal prohormone brain natriuretic peptide (NT-proBNP) and PR interval being associated with AF progression in women and factor XIIa:C1 esterase, NT-proBNP and proprotein convertase subtilisin/kexin type 9 in men. QoL was not different between sexes.

CONCLUSION

Despite older age, the incidence of AF progression was lower in women. Parameters associated with AF progression varied in part between sexes, suggesting different underlying pathophysiological mechanisms.

Detection of brain lesions after catheter ablation depends on imaging criteria: insights from AXAFA-AFNET 5 trial

AIMS

Left atrial catheter ablation is well established in patients with symptomatic atrial fibrillation (AF) but associated with risk of embolism to the brain. The present analysis aims to assess the impact of diffusion-weighted imaging (DWI) slice thickness on the rate of magnetic resonance imaging (MRI)-detected ischaemic brain lesions after ablation.

METHODS AND RESULTS

AXAFA-AFNET 5 trial (NCT02227550) participants underwent MRI using high-resolution (hr) DWI (slice thickness: 2.5-3 mm) and standard DWI (slice thickness: 5-6 mm) within 3-48 h after ablation. In 321 patients with analysable brain MRI (mean age 64 years, 33% female, median CHA2DS2-VASc 2), hrDWI detected at least one acute brain lesion in 84 (26.2%) patients and standard DWI in 60 (18.7%; P < 0.01) patients. High-resolution diffusion-weighted imaging detected more lesions compared to standard DWI (165 vs. 104; P < 0.01). The degree of agreement for lesion confirmation using hrDWI vs. standard DWI was substantial (κ = 0769). Comparing the proportion of DWI-detected lesions, lesion distribution, and total lesion volume per patient, there was no difference in the cohort of participants undergoing MRI at 1.5 T (n = 52) vs. 3 T (n = 269).

CONCLUSION

The pre-specified AXAFA-AFNET 5 sub-analysis revealed significantly increased rates of MRI-detected acute brain lesions using hrDWI instead of standard DWI in AF patients undergoing ablation. In comparison to DWI slice thickness, MRI field strength had a no significant impact in the trial. Comparing the varying rates of ablation-related MRI-detected brain lesions across previous studies has to consider these technical parameters. Future studies should use hrDWI, as feasibility was demonstrated in the multicentre AXAFA-AFNET 5 trial.

Multi-modal characterization of the left atrium by a fully automated integration of pre-procedural cardiac imaging and electro-anatomical mapping

Background

The combination of information obtained from pre-procedural cardiac imaging and electro-anatomical mapping (EAM) can potentially help to locate new ablation targets. In this study we developed and evaluated a fully automated technique to align left atrial (LA) anatomies obtained from CT- and MRI-scans with LA anatomies obtained from EAM.

Methods

Twenty-one patients scheduled for a pulmonary vein (PV) isolation with a pre-procedural MRI were enrolled. Additionally, a recent computed tomography (CT) scan was available in 12 patients. LA anatomies were segmented from MRI-scans using ADAS-AF (Galgo Medical, Barcelona) and from the CT-scans using Slicer3D. MRI and CT anatomies were aligned with the EAM anatomy using an iterative closest plane-to-plane algorithm. Initially, the algorithm included the PVs, LA appendage and mitral valve anulus as they are the most distinctive landmarks. Subsequently, the algorithm was applied again, excluding these structures, with only three iterative steps to refine the alignment of the true LA surface. The result of the alignments was quantified by the Euclidian distance between the aligned anatomies after excluding PVs, LA appendage and mitral anulus.

Results

Our algorithm successfully aligned 20/21 MRI anatomies and 11/12 CT anatomies with the corresponding EAM anatomies. The average median residual distances were 1.9 ± 0.6 mm and 2.5 ± 0.8 mm for MRI and CT anatomies respectively. The average LA surface with a residual distance less than 5.00 mm was 89 ± 9% and 89 ± 10% for MRI and CT anatomies respectively.

Conclusion

An iterative closest plane-to-plane algorithm is a reliable method to automatically align pre-procedural cardiac images with anatomies acquired during ablation procedures.

Repurposing catheter ablation work-up to detect expiratory airflow limitation in patients with atrial fibrillation

Background

In atrial fibrillation (AF) patients, presence of expiratory airflow limitation may negatively impact treatment outcomes. AF patients are not routinely screened for expiratory airflow limitation, but existing examinations can help identify at-risk individuals. We aimed to assess the diagnostic value of repurposing existing assessments from the pre-ablation work-up to identify and understand the characteristics of affected patients.

Methods

We screened 110 consecutive AF patients scheduled for catheter ablation with handheld spirometry. Routine pre-ablation work-up included cardiac computed tomographic angiography (CCTA), transthoracic echocardiography and polygraphy. CCTA was analyzed qualitatively for emphysema and airway abnormalities. Multivariate logistic regression analysis was performed to determine predictors of expiratory airflow limitation.

Results

We found that 25 % of patients had expiratory airflow limitation, which was undiagnosed in 86 % of these patients. These patients were more likely to have pulmonary abnormalities on CCTA, including emphysema (odds ratio [OR] 4.2, 95 % confidence interval [CI] 1.12-15.1, p < 0.05) and bronchial wall thickening (OR 2.6, 95 % CI 1.0-6.5, p < 0.05). The absence of pulmonary abnormalities on CCTA accurately distinguished patients with normal lung function from those with airflow limitation (negative predictive value: 85 %). Echocardiography and polygraphy did not contribute significantly to identifying airflow limitation.

Conclusions

In conclusion, routine pre-ablation CCTA can detect pulmonary abnormalities in AF patients with airflow limitation, guiding further pulmonary assessment. Future studies should investigate its impact on ablation procedure success.

Heart Failure, Female Sex, and Atrial Fibrillation Are the Main Drivers of Human Atrial Cardiomyopathy: Results From the CATCH ME Consortium

BACKGROUND

Atrial cardiomyopathy (atCM) is an emerging prognostic factor in cardiovascular disease. Fibrotic remodeling, cardiomyocyte hypertrophy, and capillary density are hallmarks of atCM. The contribution of etiological factors and atrial fibrillation (AF) to the development of differential atCM phenotypes has not been quantified. This study aimed to evaluate the association between histological features of atCM and the clinical phenotype.

METHODS AND RESULTS

We examined left atrial (LA, n=95) and right atrial (RA, n=76) appendages from a European cohort of patients undergoing cardiac surgery. Quantification of histological atCM features was performed following wheat germ agglutinin/CD31/vimentin staining. The contributions of AF, heart failure, sex, and age to histological characteristics were determined with multiple linear regression models. Persistent AF was associated with increased endomysial fibrosis (LA: +1.13±0.47 μm, P=0.038; RA: +0.94±0.38 μm, P=0.041), whereas total extracellular matrix content was not. Men had larger cardiomyocytes (LA: +1.92±0.72 μm, P<0.001), while women had more endomysial fibrosis (LA: +0.99±0.56 μm, P=0.003). Patients with heart failure showed more endomysial fibrosis (LA: +1.85±0.48 μm, P<0.001) and extracellular matrix content (LA: +3.07±1.29%, P=0.016), and a higher capillary density (LA: +0.13±0.06, P=0.007) and size (LA: +0.46±0.22 μm, P=0.044). Fuzzy k-means clustering of histological features identified 2 subtypes of atCM: 1 characterized by enhanced endomysial fibrosis (LA: +3.17 μm, P<0.001; RA: +2.86 μm, P<0.001), extracellular matrix content (LA: +3.53%, P<0.001; RA: +6.40%, P<0.001) and fibroblast density (LA: +4.38%, P<0.001), and 1 characterized by cardiomyocyte hypertrophy (LA: +1.16 μm, P=0.008; RA: +2.58 μm, P<0.001). Patients with fibrotic atCM were more frequently female (LA: odds ratio [OR], 1.33, P=0.002; RA: OR, 1.54, P=0.004), with persistent AF (LA: OR, 1.22, P=0.036) or heart failure (LA: OR, 1.62, P<0.001). Hypertrophic features were more common in men (LA: OR=1.33, P=0.002; RA: OR, 1.54, P=0.004).

CONCLUSIONS

Fibrotic atCM is associated with female sex, persistent AF, and heart failure, while hypertrophic features are more common in men.

An angiopoietin 2, FGF23, and BMP10 biomarker signature differentiates atrial fibrillation from other concomitant cardiovascular conditions

Early detection of atrial fibrillation (AF) enables initiation of anticoagulation and early rhythm control therapy to reduce stroke, cardiovascular death, and heart failure. In a cross-sectional, observational study, we aimed to identify a combination of circulating biomolecules reflecting different biological processes to detect prevalent AF in patients with cardiovascular conditions presenting to hospital. Twelve biomarkers identified by reviewing literature and patents were quantified on a high-precision, high-throughput platform in 1485 consecutive patients with cardiovascular conditions (median age 69 years [Q1, Q3 60, 78]; 60% male). Patients had either known AF (45%) or AF ruled out by 7-day ECG-monitoring. Logistic regression with backward elimination and a neural network approach considering 7 key clinical characteristics and 12 biomarker concentrations were applied to a randomly sampled discovery cohort (n = 933) and validated in the remaining patients (n = 552). In addition to age, sex, and body mass index (BMI), BMP10, ANGPT2, and FGF23 identified patients with prevalent AF (AUC 0.743 [95% CI 0.712, 0.775]). These circulating biomolecules represent distinct pathways associated with atrial cardiomyopathy and AF. Neural networks identified the same variables as the regression-based approach. The validation using regression yielded an AUC of 0.719 (95% CI 0.677, 0.762), corroborated using deep neural networks (AUC 0.784 [95% CI 0.745, 0.822]). Age, sex, BMI and three circulating biomolecules (BMP10, ANGPT2, FGF23) are associated with prevalent AF in unselected patients presenting to hospital. Findings should be externally validated. Results suggest that age and different disease processes approximated by these three biomolecules contribute to AF in patients. Our findings have the potential to improve screening programs for AF after external validation.

Long-Term Training Increases Atrial Fibrillation Sustainability in Standardbred Racehorses

Atrial fibrillation (AF) is more prevalent in athletes, and currently, the mechanisms are not fully understood. Atrial fibrillation inducibility and stability was investigated in trained and untrained Standardbred racehorses. The horses underwent echocardiography for evaluation of atrial size. High-density mapping during AF was performed, and the presence of structural remodeling, as well as the expression of inflammatory and pro-inflammatory markers in the atria, was studied. Atrial fibrillation sustained significantly longer after tachypacing in the trained horses, whereas no difference in AF inducibility was found. The untrained horses displayed a significant difference in the AF complexity when comparing right and left atria, whereas such difference was not observed in the trained animals. No evidence of increased structural remodeling or inflammation could be identified. Left atrial dimensions were not significantly increased. The increased AF sustainability in trained horses was not related to fibrosis or inflammation as seen in other animal exercise models.

Anticoagulation with Edoxaban in Patients with Atrial High-Rate Episodes

BACKGROUND

Device-detected atrial high-rate episodes (AHREs) are atrial arrhythmias detected by implanted cardiac devices. AHREs resemble atrial fibrillation but are rare and brief. Whether the occurrence of AHREs in patients without atrial fibrillation (as documented on a conventional electrocardiogram [ECG]) justifies the initiation of anticoagulants is not known.

METHODS

We conducted an event-driven, double-blind, double-dummy, randomized trial involving patients 65 years of age or older who had AHREs lasting for at least 6 minutes and who had at least one additional risk factor for stroke. Patients were randomly assigned in a 1:1 ratio to receive edoxaban or placebo. The primary efficacy outcome was a composite of cardiovascular death, stroke, or systemic embolism, evaluated in a time-to-event analysis. The safety outcome was a composite of death from any cause or major bleeding.

RESULTS

The analysis population consisted of 2536 patients (1270 in the edoxaban group and 1266 in the placebo group). The mean age was 78 years, 37.4% were women, and the median duration of AHREs was 2.8 hours. The trial was terminated early, at a median follow-up of 21 months, on the basis of safety concerns and the results of an independent, informal assessment of futility for the efficacy of edoxaban; at termination, the planned enrollment had been completed. A primary efficacy outcome event occurred in 83 patients (3.2% per patient-year) in the edoxaban group and in 101 patients (4.0% per patient-year) in the placebo group (hazard ratio, 0.81; 95% confidence interval [CI], 0.60 to 1.08; P = 0.15). The incidence of stroke was approximately 1% per patient-year in both groups. A safety outcome event occurred in 149 patients (5.9% per patient-year) in the edoxaban group and in 114 patients (4.5% per patient-year) in the placebo group (hazard ratio, 1.31; 95% CI, 1.02 to 1.67; P = 0.03). ECG-diagnosed atrial fibrillation developed in 462 of 2536 patients (18.2% total, 8.7% per patient-year).

CONCLUSIONS

Among patients with AHREs detected by implantable devices, anticoagulation with edoxaban did not significantly reduce the incidence of a composite of cardiovascular death, stroke, or systemic embolism as compared with placebo, but it led to a higher incidence of a composite of death or major bleeding. The incidence of stroke was low in both groups. (Funded by the German Center for Cardiovascular Research and others; NOAH-AFNET 6 ClinicalTrials.gov number, NCT02618577; ISRCTN number, ISRCTN17309850.).

Brady- and tachyarrhythmias detected by continuous rhythm monitoring in paroxysmal atrial fibrillation

OBJECTIVE

Atrial fibrillation (AF) is associated with adverse events including conduction disturbances, ventricular arrhythmias and sudden death. The aim of this study was to examine brady- and tachyarrhythmias using continuous rhythm monitoring in patients with paroxysmal self-terminating AF (PAF).

METHODS

In this multicentre observational substudy to the Reappraisal of Atrial Fibrillation: interaction between hyperCoagulability, Electrical remodelling and Vascular destabilisation in the progression of AF (RACE V), we included 392 patients with PAF and at least 2 years of continuous rhythm monitoring. All patients received an implantable loop recorder, and all detected episodes of tachycardia ≥182 beats per minute (BPM), bradycardia ≤30 BPM or pauses ≥5 s were adjudicated by three physicians.

RESULTS

Over 1272 patient-years of continuous rhythm monitoring, we adjudicated 1940 episodes in 175 patients (45%): 106 (27%) patients experienced rapid AF or atrial flutter (AFL), pauses ≥5 s or bradycardias ≤30 BPM occurred in 47 (12%) patients and in 22 (6%) patients, we observed both episode types. No sustained ventricular tachycardias occurred. In the multivariable analysis, age >70 years (HR 2.3, 95% CI 1.4 to 3.9), longer PR interval (HR 1.9, 1.1-3.1), CHA2DS2-VASc score ≥2 (HR 2.2, 1.1-4.5) and treatment with verapamil or diltiazem (HR 0.4, 0.2-1.0) were significantly associated with bradyarrhythmia episodes. Age >70 years was associated with lower rates of tachyarrhythmias.

CONCLUSIONS

In a cohort exclusive to patients with PAF, almost half experienced severe bradyarrhythmias or AF/AFL with rapid ventricular rates. Our data highlight a higher than anticipated bradyarrhythmia risk in PAF.

TRIAL REGISTRATION NUMBER

NCT02726698.

Left Bundle Branch Area Pacing and Atrioventricular Node Ablation in a Single-Procedure Approach for Elderly Patients with Symptomatic Atrial Fibrillation

BACKGROUND

Implantation of a permanent pacemaker and atrioventricular (AV) node ablation (pace-and-ablate) is an established approach for rate and symptom control in elderly patients with symptomatic atrial fibrillation (AF). Left bundle branch area pacing (LBBAP) is a physiological pacing strategy that might overcome right ventricular pacing-induced dyssynchrony. In this study, the feasibility and safety of performing LBBAP and AV node ablation in a single procedure in the elderly was investigated.

METHODS

Consecutive patients with symptomatic AF referred for pace-and-ablate underwent the treatment in a single procedure. Data on procedure-related complications and lead stability were collected at regular follow-up at one day, ten days and six weeks after the procedure and continued every six months thereafter.

RESULTS

25 patients (mean age 79.2 ± 4.2 years) were included and underwent successful LBBAP. In 22 (88%) patients, AV node ablation and LBBAP were performed in the same procedure. AV node ablation was postponed in two patients due to lead-stability concerns and in one patient on their own request. No complications related to the single-procedure approach were observed with no lead-stability issues at follow-up.

CONCLUSIONS

LBBAP combined with AV node ablation in a single procedure is feasible and safe in elderly patients with symptomatic AF.

Atrial fibrillation-specific refinement of the STOP-Bang sleep apnoea screening questionnaire: insights from the Virtual-SAFARI study

BACKGROUND

Sleep-disordered breathing (SDB) is prevalent in up to 50% of patients referred for atrial fibrillation (AF) catheter ablation (CA). Currently, it remains unclear how to improve pre-selection for SDB screening in patients with AF.

AIM

We aimed to (1) assess the accuracy of the STOP-Bang screening questionnaire for detection of SDB within an AF population referred for CA; (2) derive a refined, AF-specific SDB score to improve pre-selection.

METHODS

Consecutive AF patients referred for CA without a history of SDB and/or SDB screening were included. Patients were digitally referred to the previously implemented Virtual-SAFARI SDB screening and management pathway including a home sleep test. An apnoea-hypopnoea index (AHI) of  ≥ 15 was interpreted as moderate-to-severe SDB. Logistic regression analysis was used to assess characteristics associated with moderate-to-severe SDB to refine pre-selection for SDB screening.

RESULTS

Of 206 included patients, 51% were diagnosed with moderate-to-severe SDB. The STOP-Bang questionnaire performed poorly in detecting SDB, with an area under the receiver operating characteristic curve (AUROC) of 0.647 (95% Confidence-Interval (CI) 0.573-0.721). AF-specific refinement resulted in the BOSS-GAP score. Therein, BMI with cut-off point ≥ 27 kg/m2 and previous stroke or transient ischaemic attack (TIA) were added, while tiredness and neck circumference were removed. The BOSS-GAP score performed better with an AUROC of 0.738 (95% CI 0.672-0.805) in the overall population.

CONCLUSION

AF-specific refinement of the STOP-Bang questionnaire moderately improved detection of SDB in AF patients referred for CA. Whether questionnaires bring benefits for pre-selection of SDB compared to structural screening in patients with AF requires further studies.

TRIAL REGISTRATION NUMBER

ISOLATION was registered NCT04342312, 13-04-2020.

Quantifying a spectrum of clinical response in atrial tachyarrhythmias using spatiotemporal synchronization of electrograms

AIMS

There is a clinical spectrum for atrial tachyarrhythmias wherein most patients with atrial tachycardia (AT) and some with atrial fibrillation (AF) respond to ablation, while others do not. It is undefined if this clinical spectrum has pathophysiological signatures. This study aims to test the hypothesis that the size of spatial regions showing repetitive synchronized electrogram (EGM) shapes over time reveals a spectrum from AT, to AF patients who respond acutely to ablation, to AF patients without acute response.

METHODS AND RESULTS

We studied n = 160 patients (35% women, 65.0 ± 10.4 years) of whom (i) n = 75 had AF terminated by ablation propensity matched to (ii) n = 75 without AF termination and (iii) n = 10 with AT. All patients had mapping by 64-pole baskets to identify areas of repetitive activity (REACT) to correlate unipolar EGMs in shape over time. Synchronized regions (REACT) were largest in AT, smaller in AF termination, and smallest in non-termination cohorts (0.63 ± 0.15, 0.37 ± 0.22, and 0.22 ± 0.18, P < 0.001). Area under the curve for predicting AF termination in hold-out cohorts was 0.72 ± 0.03. Simulations showed that lower REACT represented greater variability in clinical EGM timing and shape. Unsupervised machine learning of REACT and extensive (50) clinical variables yielded four clusters of increasing risk for AF termination (P < 0.01, χ2), which were more predictive than clinical profiles alone (P < 0.001).

CONCLUSION

The area of synchronized EGMs within the atrium reveals a spectrum of clinical response in atrial tachyarrhythmias. These fundamental EGM properties, which do not reflect any predetermined mechanism or mapping technology, predict outcome and offer a platform to compare mapping tools and mechanisms between AF patient groups.

Time of onset of atrial fibrillation and atrial fibrillation progression data from the RACE V study

AIMS

Atrial fibrillation (AF) progression is associated with adverse outcome, but the role of the circadian or diurnal pattern of AF onset remains unclear. We aim to assess the association between the time of onset of AF episodes with the clinical phenotype and AF progression in patients with self-terminating AF.

METHODS AND RESULTS

The Reappraisal of AF: Interaction Between Hypercoagulability, Electrical Remodelling, and Vascular Destabilization in the Progression of AF study included patients with self-terminating AF who underwent extensive phenotyping at baseline and continuous rhythm monitoring with an implantable loop recorder (ILR). In this subanalysis, ILR data were used to assess the development of AF progression and the diurnal pattern of AF onset: predominant (>80%) nocturnal AF, predominant daytime AF, or mixed AF without a predominant diurnal AF pattern. The median follow-up was 2.2 (1.6-2.8) years. The median age was 66 (59-71) years, and 117 (42%) were women. Predominant nocturnal (n = 40) and daytime (n = 43) AF onset patients had less comorbidities compared to that of mixed (n = 195) AF patients (median 2 vs. 2 vs. 3, respectively, P = 0.012). Diabetes was more common in the mixed group (12% vs. 5% vs. 0%, respectively, P = 0.031), whilst obesity was more frequent in the nocturnal group (38% vs. 12% vs. 27%, respectively, P = 0.028). Progression rates in the nocturnal vs. daytime vs. mixed groups were 5% vs. 5% vs. 24%, respectively (P = 0.013 nocturnal vs. mixed and P = 0.008 daytime vs. mixed group, respectively).

CONCLUSION

In self-terminating AF, patients with either predominant nocturnal or daytime onset of AF episodes had less associated comorbidities and less AF progression compared to that of patients with mixed onset of AF.

CLINICAL TRIAL REGISTRATION

NCT02726698.

Evaluating subclinical left ventricular and left atrial dysfunction in idiopathic atrial fibrillation: A speckle-tracking based strain-analysis

OBJECTIVE

A subset of patients with atrial fibrillation (AF) presents without established AF risk factors and normal left ventricular (LV) systolic function, called idiopathic AF (IAF). Traditionally, echocardiography derived LV dimensions and ejection fraction (EF) are used to exclude LV dysfunction in IAF, but their sensitivity is limited. Our objective is to evaluate the presence of subtle alterations in LV function despite normal LVEF in patients with IAF compared to healthy controls, using speckle-tracking echocardiography (STE) based global longitudinal strain (GLS).

METHODS

Standard transthoracic echocardiography was performed in 80 patients with IAF and 129 healthy controls. Patients with overt cardiac disease as well as known established AF risk factors were excluded. STE analysis was performed to assess GLS of the LV, and left atrial strain (LAS).

RESULTS

LVEF was normal and comparable between patients with IAF and healthy controls (63 ± 4% for both groups; p = 0.801). Mean GLS was within normal limits for both groups but statistically significantly more negative in patients with IAF (-20.6 ± 2.5% vs. -19.7 ± 2.5%; p = 0.016), however not when indexed for ventricular cycle length (p = 0.784). No differences in LA volume or non-indexed LAS were seen in patients with IAF compared to healthy controls.

CONCLUSIONS

In this selected group of IAF patients, STE did not detect any overt LV or LA dysfunction compared to healthy controls. Thus, IAF occurred in these patients not only in the absence of established AF risk factors but also without evidence of ventricular dysfunction.

High-density and high coverage composite mapping of repetitive atrial activation patterns

BACKGROUND

Repetitive atrial activation patterns (RAAPs) during atrial fibrillation (AF) may be associated with localized mechanisms that maintain AF. Current electro-anatomical mapping systems are unsuitable for analyzing RAAPs due to the trade-off between spatial coverage and electrode density in clinical catheters. This work proposes a technique to overcome this trade-off by constructing composite maps from spatially overlapping sequential recordings.

METHODS

High-density epicardial contact mapping was performed during open-chest surgery in goats (n=16, left and right atria) with 3 or 22 weeks of sustained AF (249-electrode array, electrode distance 2.4 mm). A dataset mimicking sequential recordings was generated by segmenting the grid into four spatially overlapping regions (each region 6.5 cm², 48±10% overlap) without temporal overlap. RAAPs were detected in each region using recurrence plots of activation times. RAAPs in two different regions were joined in case of RAAP cross-recurrence between overlapping electrodes. We quantified the reconstruction success rate and quality of the composite maps.

RESULTS

Of 1021 RAAPs found in the full mapping array (32±13 per recording), 328 spatiotemporally stable RAAPs were analyzed. 247 composite maps were generated (75% success) with a quality of 0.86±0.21 (Pearson correlation). Success was significantly affected by the RAAP area. Quality was weakly correlated with the number of repetitions of RAAPs (r=0.13, p<0.05) and not affected by the atrial side (left or right) or AF duration (3 or 22 weeks of AF).

CONCLUSIONS

Constructing composite maps by combining spatially overlapping sequential recordings is feasible. Interpretation of these maps can play a central role in ablation planning.

Genetic architecture of spatial electrical biomarkers for cardiac arrhythmia and relationship with cardiovascular disease

The 3-dimensional spatial and 2-dimensional frontal QRS-T angles are measures derived from the vectorcardiogram. They are independent risk predictors for arrhythmia, but the underlying biology is unknown. Using multi-ancestry genome-wide association studies we identify 61 (58 previously unreported) loci for the spatial QRS-T angle (N = 118,780) and 11 for the frontal QRS-T angle (N = 159,715). Seven out of the 61 spatial QRS-T angle loci have not been reported for other electrocardiographic measures. Enrichments are observed in pathways related to cardiac and vascular development, muscle contraction, and hypertrophy. Pairwise genome-wide association studies with classical ECG traits identify shared genetic influences with PR interval and QRS duration. Phenome-wide scanning indicate associations with atrial fibrillation, atrioventricular block and arterial embolism and genetically determined QRS-T angle measures are associated with fascicular and bundle branch block (and also atrioventricular block for the frontal QRS-T angle). We identify potential biology involved in the QRS-T angle and their genetic relationships with cardiovascular traits and diseases, may inform future research and risk prediction.

Clinical utility of the 4S-AF scheme in predicting progression of atrial fibrillation: data from the RACE V study

AIMS

The recent 4S-AF (scheme proposed by the 2020 ESC AF guidelines to address stroke risk, symptom severity, severity of AF burden and substrate of AF to provide a structured phenotyping of AF patients in clinical practice to guide therapy and assess prognosis) scheme has been proposed as a structured scheme to characterize patients with atrial fibrillation (AF). We aimed to assess whether the 4S-AF scheme predicts AF progression in patients with self-terminating AF.

METHODS AND RESULTS

We analysed 341 patients with self-terminating AF included in the well-phenotyped Reappraisal of Atrial Fibrillation: Interaction between HyperCoagulability, Electrical remodelling, and Vascular Destabilization in the Progression of AF (RACE V) study. Patients had continuous monitoring with implantable loop recorders or pacemakers. AF progression was defined as progression to persistent or permanent AF or progression of self-terminating AF with >3% burden increase. Progression of AF was observed in 42 patients (12.3%, 5.9% per year). Patients were given a score based on the components of the 4S-AF scheme. Mean age was 65 [interquartile range (IQR) 58-71] years, 149 (44%) were women, 103 (49%) had heart failure, 276 (81%) had hypertension, and 38 (11%) had coronary artery disease. Median CHA2DS2-VASc (the CHA2DS2-VASc score assesses thromboembolic risk. C, congestive heart failure/left ventricular dysfunction; H, hypertension; A2, age ≥ 75 years; D, diabetes mellitus; S2, stroke/transient ischaemic attack/systemic embolism; V, vascular disease; A, age 65-74 years; Sc, sex category (female sex)) score was 2 (IQR 2-3), and median follow-up was 2.1 (1.5-2.6) years. The average score of the 4S-AF scheme was 4.6 ± 1.4. The score points from the 4S-AF scheme did not predict the risk of AF progression [odds ratio (OR) 1.1 95% CI 0.88-1.41, C-statistic 0.53]. However, excluding the symptoms domain, resulting in the 3S-AF (4S-AF scheme without the domain symptom severity, only including stroke risk, severity of AF burden and substrate of AF) scheme, predicted the risk of progression (OR 1.59 95% CI 1.15-2.27, C-statistic 0.62) even after adjusting for sex and age.

CONCLUSIONS

In self-terminating AF patients, the 4S-AF scheme does not predict AF progression. The 3S-AF scheme, excluding the symptom domain, may be a more appropriate score to predict AF progression.

TRIAL REGISTRATION NUMBERS

Clinicaltrials.gov NCT02726698 for RACE V.

Animal models and animal-free innovations for cardiovascular research: current status and routes to be explored. Consensus document of the ESC Working Group on Myocardial Function and the ESC Working Group on Cellular Biology of the Heart

Cardiovascular diseases represent a major cause of morbidity and mortality, necessitating research to improve diagnostics, and to discover and test novel preventive and curative therapies, all of which warrant experimental models that recapitulate human disease. The translation of basic science results to clinical practice is a challenging task, in particular for complex conditions such as cardiovascular diseases, which often result from multiple risk factors and comorbidities. This difficulty might lead some individuals to question the value of animal research, citing the translational 'valley of death', which largely reflects the fact that studies in rodents are difficult to translate to humans. This is also influenced by the fact that new, human-derived in vitro models can recapitulate aspects of disease processes. However, it would be a mistake to think that animal models do not represent a vital step in the translational pathway as they do provide important pathophysiological insights into disease mechanisms particularly on an organ and systemic level. While stem cell-derived human models have the potential to become key in testing toxicity and effectiveness of new drugs, we need to be realistic, and carefully validate all new human-like disease models. In this position paper, we highlight recent advances in trying to reduce the number of animals for cardiovascular research ranging from stem cell-derived models to in situ modelling of heart properties, bioinformatic models based on large datasets, and state-of-the-art animal models, which show clinically relevant characteristics observed in patients with a cardiovascular disease. We aim to provide a guide to help researchers in their experimental design to translate bench findings to clinical routine taking the replacement, reduction, and refinement (3R) as a guiding concept.

Atrial fibrillation in the presence and absence of heart failure enhances expression of genes involved in cardiomyocyte structure, conduction properties, fibrosis, inflammation, and endothelial dysfunction

BACKGROUND

Little is known about genome-wide changes in the atrial transcriptome as a cause or consequence of atrial fibrillation (AF), and the effect of its common and clinically relevant comorbidity-heart failure (HF).

OBJECTIVE

The purpose of this study was to explore candidate disease processes for AF by investigating gene expression changes in atrial tissue samples from patients with and without AF, stratified by HF.

METHODS

RNA sequencing was performed in right and left atrial appendage tissue in 195 patients undergoing open heart surgery from centers participating in the CATCH-ME consortium (no history of AF, n = 91; paroxysmal AF, n = 53; persistent/permanent AF, n = 51). Analyses were stratified into patients with/without HF (n = 75/120) and adjusted for age, sex, atrial side, and a combination of clinical characteristics.

RESULTS

We identified 35 genes associated with persistent AF compared to patients without a history of AF, both in the presence or absence of HF (false discovery rate <0.05). These were mostly novel associations, including 13 long noncoding RNAs. Genes were involved in regulation of cardiomyocyte structure, conduction properties, fibrosis, inflammation, and endothelial dysfunction. Gene set enrichment analysis identified mainly inflammatory gene sets to be enriched in AF patients without HF, and gene sets involved in cellular respiration in AF patients with HF.

CONCLUSION

Analysis of atrial gene expression profiles identified numerous novel genes associated with persistent AF, in the presence or absence of HF. Interestingly, no consistent transcriptional changes were associated with paroxysmal AF, suggesting that AF-induced changes in gene expression predominate other changes.

Smartphone and wearable detected atrial arrhythmias in Older Adults: Results of a fully digital European Case finding study

Aims

Simplified detection of atrial arrhythmias via consumer-electronics would enable earlier therapy in at-risk populations. Whether this is feasible and effective in older populations is not known.

Methods and results

The fully remote, investigator-initiated Smartphone and wearable detected atrial arrhythmia in Older Adults Case finding study (Smart in OAC-AFNET 9) digitally enrolled participants ≥65 years without known atrial fibrillation, not receiving oral anticoagulation in Germany, Poland, and Spain for 8 weeks. Participants were invited by media communications and direct contacts. Study procedures adhered to European data protection. Consenting participants received a wristband with a photoplethysmography sensor to be coupled to their smartphone. The primary outcome was the detection of atrial arrhythmias lasting 6 min or longer in the first 4 weeks of monitoring. Eight hundred and eighty-two older persons (age 71 ± 5 years, range 65-90, 500 (57%) women, 414 (47%) hypertension, and 97 (11%) diabetes) recorded signals. Most participants (72%) responded to adverts or word of mouth, leaflets (11%) or general practitioners (9%). Participation was completely remote in 469/882 persons (53%). During the first 4 weeks, participants transmitted PPG signals for 533/696 h (77% of the maximum possible time). Atrial arrhythmias were detected in 44 participants (5%) within 28 days, and in 53 (6%) within 8 weeks. Detection was highest in the first monitoring week [incidence rates: 1st week: 3.4% (95% confidence interval 2.4-4.9); 2nd-4th week: 0.55% (0.33-0.93)].

Conclusion

Remote, digitally supported consumer-electronics-based screening is feasible in older European adults and identifies atrial arrhythmias in 5% of participants within 4 weeks of monitoring (NCT04579159).

A new efficient and integrated pathway for patient evaluation prior to atrial fibrillation ablation

AIM

In this quality improvement project, a care pathway for patients considered for atrial fibrillation (AF) ablation was optimized with the goals to improve the patient journey and simultaneously integrate prospective data collection into the clinical process.

METHODS AND RESULTS

The Lean Six Sigma approach was used to map the pre-existing process, identify constraints and formulate countermeasures. The percentage of patients going through the full pre-ablation preparation that eventually underwent AF ablation, number of hospital visits and consultations, pathway compliance, and completeness of scientific data were measured before and after pathway optimisation. Constraints in the process were (1) lack of standardized processes, (2) inefficient use of resources, (3) lack of multidisciplinary integration, (4) lack of research integration, and (5) suboptimal communication. The impact of the corresponding countermeasures (defining a uniform process, incorporating 'go/no-go' moment, introducing a 'one-stop-shop', integrating prospective data collection, and improving communication) was studied for 33 patients before and 26 patients after pathway optimisation. After optimisation, the percentage of patients receiving a full pre-ablation preparation that eventually underwent AF ablation increased from 59% to 94% (p < 0.01). Fewer hospital visits (3.2 ± 1.2 versus 2.3 ± 0.8, p = 0.01) and electrophysiologist consultations (1.8 ± 0.7 versus 1.0 ± 0.3, p < 0.01) were required after pathway optimisation. Pathway compliance and complete collection of scientific data increased significantly (3% versus 73%, p < 0.01 and 15% versus 73%, p < 0.01, respectively).

CONCLUSION

The optimisation project resulted in a more efficient evaluation of patients considered for AF ablation. The new more efficient process includes prospective data collection and facilitates easy conduct of research studies focused on improvements of patient outcomes.

We all know A and B, but what about C? Exploring the management of modifiable risk factors in patients with atrial fibrillation

Background

The European Society of Cardiology (ESC) guidelines for the management of atrial fibrillation (AF) advise to treat AF according to the ABC pathway: A, anticoagulation, B, better symptom control, and C, comorbidities and cardiovascular risk factor management. Optimal treatment of comorbidities and risk factors slows AF progression and improves success rates of rhythm interventions for AF. However, several studies report underdiagnosis and therefore possible undertreatment for common cardiovascular comorbidities.

Purpose

This study aims to evaluate how common modifiable cardiovascular risk factors are managed in AF patients referred for catheter ablation.

Methods

This is a substudy of the ISOLATION study, a prospective cohort study including consecutive patients with paroxysmal or persistent AF referred for AF ablation. Screening for common modifiable risk factors for AF is structurally embedded in the work-up for AF ablation in the two participating centres. In the present study the prevalence of the following risk factors at this screening moment was assessed: (1) body mass index (BMI) above the target BMI for ablation (≥27 kg/m2), (2) hypertension, defined as on-site systolic blood pressure &gt;130 mmHg and/or diastolic blood pressure &gt;80 mmHg, (3) decreased glucose tolerance or diabetes mellitus, defined as HbA1c ≥6.5%, (4) dyslipidaemia, defined as low-density lipoprotein (LDL) ≥2.5 mmol/l, (5) regular alcohol consumption, defined as self-reported consumption of &gt;15 standardized units/week, and (6) sleep disordered breathing (SDB), defined as apnoea-hypopnoea index (AHI) ≥15 assessed with home sleep tests (subset of patients).

Results

Among the 981 patients studied (median age 65 [59–71] years old, 64% male, 69% paroxysmal AF), previously diagnosed comorbidities were common (46% hypertension, 7% diabetes, 22% dyslipidaemia, 10% SDB), and a large proportion of patients received targeted treatment (Table 1). However, non-optimally managed risk factors remained significant (Figure 1). BMI ≥27 kg/m2 was present in 56% of patients. High systolic and diastolic blood pressure were present in 62% and 51% of patients, respectively, and any form of high blood pressure (either systolic or diastolic) was seen in 72% of patients. HbA1c was found to be above target ranges in 9% patients and LDL in 56%. A weekly alcohol consumption of ≥15 units was reported by 4% of patients. Screening for SDB was performed in a subset of patients (n=287), for whom AHI was ≥15 in 52%. Overall, 9% of patients had 4 or more non-optimally controlled modifiable risk factors, whereas the median number of modifiable risk factors was 2 [1–3].

Conclusions

Structural screening revealed a high prevalence of non-optimally controlled modifiable cardiovascular risk factors in patients referred for AF catheter ablation. According to recent ESC guidelines, improving treatment of comorbidities may improve AF ablation success rates and even reduce mortality.

Funding Acknowledgement

Type of funding sources: None.

The use of novel 3D dark-blood late gadolinium enhancement MRI to determine the optimal threshold for atrial scar after pulmonary vein isolation ablation

Background

Dark-blood late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) is proved to be superior to bright-blood LGE MRI in localising subtle subendocardial scar in the ventricles, because of improved contrast between myocardial scar and blood. However, dark-blood LGE MRI has not yet been applied to identify atrial scar in the left atrium (LA) and therefore its threshold to determine scar is unknown.

Purpose

To determine the optimal intensity threshold for 3D dark-blood LGE MRI for atrial ablation scar after pulmonary vein isolation (PVI)

Methods

Twelve re-do PVI patients with symptomatic atrial fibrillation (AF) who underwent pre-procedural 3D dark-blood LGE MRI were included. The image intensity ratio (IIR = myocardial intensity normalized to the blood pool) from the LGE MRI were calculated using ADAS-AF. High-density bipolar voltages (BiV) maps were recorded during sinus rhythm prior to ablation. All BiV locations ≤5 mm from the ADAS LA anatomy were compared with the corresponding IIR, using custom-made software in MATLAB. To achieve an equal ratio between scar (BiV ≤0.15 mV) and non-scar (BiV &gt;0.15 mV) for each patient, non-scar pairs were randomly resampled to the same number as scar pairs. This was repeated 10 times and for every random selection, receiver operating characteristics (ROC) analysis was performed to determine the optimal IIR threshold (provided by the Youden's index) for scar defined as BiV &lt;0.15 mV (Figure 1). All IIR thresholds and areas under the curve were averaged to determine the overall performance and optimal IIR threshold.

Results

Of the 12 included patients, 8 had prior cryo PVI, 2 radiofrequency PVI, and 2 surgical/hybrid AF ablation. ROC curve analysis estimated the average optimal threshold for predicting BiV &lt;0.15 mV to be an IIR of 1.106, with a mean area under the curve (AUC) of 0.73 (Figure 1). Figure 2 shows two examples of the IIR map (A), BiV map (B), and the correspondence map (C) providing information on spatial agreement between IIR and BiV. This individual qualitative assessment provides insight into the spatial variation between techniques and may facilitate future studies on the pathophysiological understanding of atrial ablation scarring.

Conclusion

This is the first study to use the novel 3D dark-blood whole heart LGE MRI to evaluate LA ablation scar after PVI. Based on the ROC analyses, an IIR of 1.106 is the optimal threshold for atrial ablation scar, defined as high density bipolar voltage &lt;0.15 mV.

Funding Acknowledgement

Type of funding sources: None.

Genetic analyses of the electrocardiographic QT interval and its components identify additional loci and pathways

The QT interval is an electrocardiographic measure representing the sum of ventricular depolarization and repolarization, estimated by QRS duration and JT interval, respectively. QT interval abnormalities are associated with potentially fatal ventricular arrhythmia. Using genome-wide multi-ancestry analyses (>250,000 individuals) we identify 177, 156 and 121 independent loci for QT, JT and QRS, respectively, including a male-specific X-chromosome locus. Using gene-based rare-variant methods, we identify associations with Mendelian disease genes. Enrichments are observed in established pathways for QT and JT, and previously unreported genes indicated in insulin-receptor signalling and cardiac energy metabolism. In contrast for QRS, connective tissue components and processes for cell growth and extracellular matrix interactions are significantly enriched. We demonstrate polygenic risk score associations with atrial fibrillation, conduction disease and sudden cardiac death. Prioritization of druggable genes highlight potential therapeutic targets for arrhythmia. Together, these results substantially advance our understanding of the genetic architecture of ventricular depolarization and repolarization.

Association between comorbidities and left and right atrial dysfunction in patients with paroxysmal atrial fibrillation: Analysis of AF-RISK

BACKGROUND

To identify the association between comorbidities and left atrial (LA) and right atrial (RA) function in patients with paroxysmal atrial fibrillation (AF).

METHODS

This is a cross-sectional study. Speckle-tracking echocardiography was performed in 344 patients with paroxysmal AF at baseline, and available in 298 patients after 1-year follow-up. The number of comorbidities (hypertension, diabetes mellitus, coronary artery disease, body mass index > 25 kg/m², age > 65 years, moderate to severe mitral valve regurgitation and kidney dysfunction (estimated glomerular filtration rate < 60 ml/min/1.73 m²)) was determined and the association with atrial strain was tested.

RESULTS

Mean age of the patients was 58 (SD 12) years and 137 patients were women (40%). Patients with a higher number of comorbidities had larger LA volumes (p for trend <0.001), and had a decrease in all strain phases from the LA and RA, except for the RA contraction phase (p for trend 0.47). A higher number of comorbidities was associated with LA reservoir and conduit strain decrease independently of LA volume (p < 0.001, p < 0.001 respectively). Patients with 1-2 comorbidities, but not patients with 3 or more comorbidities, showed a further progression of impaired LA and RA function in almost all atrial strain phases at 14 [13-17] months follow-up.

CONCLUSIONS

In patients with paroxysmal AF, individual and combined comorbidities are related to lower LA and RA strain. In patients with few comorbidities, impairment in atrial function progresses during one year of follow-up. Whether comorbidity management prevents or reverses decrease in atrial function warrants further study.

Early diagnosis and better rhythm management to improve outcomes in patients with atrial fibrillation: the 8th AFNET/EHRA consensus conference

Despite marked progress in the management of atrial fibrillation (AF), detecting AF remains difficult and AF-related complications cause unacceptable morbidity and mortality even on optimal current therapy. This document summarizes the key outcomes of the 8th AFNET/EHRA Consensus Conference of the Atrial Fibrillation NETwork (AFNET) and the European Heart Rhythm Association (EHRA). Eighty-three international experts met in Hamburg for 2 days in October 2021. Results of the interdisciplinary, hybrid discussions in breakout groups and the plenary based on recently published and unpublished observations are summarized in this consensus paper to support improved care for patients with AF by guiding prevention, individualized management, and research strategies. The main outcomes are (i) new evidence supports a simple, scalable, and pragmatic population-based AF screening pathway; (ii) rhythm management is evolving from therapy aimed at improving symptoms to an integrated domain in the prevention of AF-related outcomes, especially in patients with recently diagnosed AF; (iii) improved characterization of atrial cardiomyopathy may help to identify patients in need for therapy; (iv) standardized assessment of cognitive function in patients with AF could lead to improvement in patient outcomes; and (v) artificial intelligence (AI) can support all of the above aims, but requires advanced interdisciplinary knowledge and collaboration as well as a better medico-legal framework. Implementation of new evidence-based approaches to AF screening and rhythm management can improve outcomes in patients with AF. Additional benefits are possible with further efforts to identify and target atrial cardiomyopathy and cognitive impairment, which can be facilitated by AI.

Prevalence and determinants of atrial fibrillation progression in paroxysmal atrial fibrillation

OBJECTIVE

Atrial fibrillation (AF) often progresses from paroxysmal AF (PAF) to more permanent forms. To improve personalised medicine, we aim to develop a new AF progression risk prediction model in patients with PAF.

METHODS

In this interim-analysis of the Reappraisal of AF: Interaction Between HyperCoagulability, Electrical Remodelling, and Vascular Destabilisation in the Progression of AF study, patients with PAF undergoing extensive phenotyping at baseline and continuous rhythm monitoring during follow-up of ≥1 year were analysed. AF progression was defined as (1) progression to persistent or permanent AF or (2) progression of PAF with >3% burden increase. Multivariable analysis was done to identify predictors of AF progression.

RESULTS

Mean age was 65 (58-71) years, 179 (43%) were female. Follow-up was 2.2 (1.6-2.8) years, 51 of 417 patients (5.5%/year) showed AF progression. Multivariable analysis identified, PR interval, impaired left atrial function, mitral valve regurgitation and waist circumference to be associated with AF progression. Adding blood biomarkers improved the model (C-statistic from 0.709 to 0.830) and showed male sex, lower levels of factor XIIa:C1-esterase inhibitor and tissue factor pathway inhibitor, and higher levels of N-terminal pro-brain natriuretic peptide, proprotein convertase subtilisin/kexin type 9 and peptidoglycan recognition protein 1 were associated with AF progression.

CONCLUSION

In patients with PAF, AF progression occurred in 5.5%/year. Predictors for progression included markers for atrial remodelling, sex, mitral valve regurgitation, waist circumference and biomarkers associated with coagulation, inflammation, cardiomyocyte stretch and atherosclerosis. These prediction models may help to determine risk of AF progression and treatment targets, but validation is needed.

TRIAL REGISTRATION NUMBER

NCT02726698.

Rationale and Design of the ISOLATION Study: A Multicenter Prospective Cohort Study Identifying Predictors for Successful Atrial Fibrillation Ablation in an Integrated Clinical Care and Research Pathway

Introduction

Continuous progress in atrial fibrillation (AF) ablation techniques has led to an increasing number of procedures with improved outcome. However, about 30-50% of patients still experience recurrences within 1 year after their ablation. Comprehensive translational research approaches integrated in clinical care pathways may improve our understanding of the complex pathophysiology of AF and improve patient selection for AF ablation.

Objectives

Within the "IntenSive mOlecular and eLectropathological chAracterization of patienTs undergoIng atrial fibrillatiOn ablatioN" (ISOLATION) study, we aim to identify predictors of successful AF ablation in the following domains: (1) clinical factors, (2) AF patterns, (3) anatomical characteristics, (4) electrophysiological characteristics, (5) circulating biomarkers, and (6) genetic background. Herein, the design of the ISOLATION study and the integration of all study procedures into a standardized pathway for patients undergoing AF ablation are described.

Methods

ISOLATION (NCT04342312) is a two-center prospective cohort study including 650 patients undergoing AF ablation. Clinical characteristics and routine clinical test results will be collected, as well as results from the following additional diagnostics: determination of body composition, pre-procedural rhythm monitoring, extended surface electrocardiogram, biomarker testing, genetic analysis, and questionnaires. A multimodality model including a combination of established predictors and novel techniques will be developed to predict ablation success.

Discussion

In this study, several domains will be examined to identify predictors of successful AF ablation. The results may be used to improve patient selection for invasive AF management and to tailor treatment decisions to individual patients.

Replicated gene expression changes in patients with atrial fibrillation

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union Horizon 2020 CATCH ME; Cardiovascular Research Netherlands RACE V

Background

Little is known about changes in the atrial transcriptome associated with paroxysmal and persistent atrial fibrillation (AF).

Purpose

To identify major molecular mechanisms in AF, we determined consistent differential expression (DE) between atrial tissue samples from well-characterized patients with paroxysmal or persistent AF and patients without a history of AF (no AF) in two independent patient cohorts.

Methods

Poly-A tailed RNA from left and right atrial appendage tissue samples from independent discovery and replication cohorts CATCH ME (n=192) and RACE V (n=122) was sequenced and analyzed according to patient AF history. Analyses were performed stratified by atrial side, adjusting for age, sex, heart failure and a combination of clinical characteristics determined by principal component analysis. Transcripts were considered DE in CATCH ME if their fold change reached transcriptome-wide significance (false discovery rate (FDR) &lt; 0.05). DE transcripts in each rhythm comparison were replicated in RACE V if we observed a concordant direction of effect and a within-set FDR &lt; 0.05 in the same comparison.

Results

Persistent AF compared to no AF was associated with 184 left atrial DE transcripts in CATCH ME of which 85 (46%) were replicated in RACE V, and with 208 right atrial DE transcripts in CATCH ME of which 86 (41%) were replicated in RACE V. Overall, 26 transcripts were discovered and replicated in both atria. Discovered but non-replicated transcripts often did exhibit concordant direction of effect (left: 78%, right: 83%). Replicated transcripts consisted of protein coding genes, antisense and non-coding RNAs. Protein coding genes showed involvement in pathways linking persistent AF to cardiomyocyte structure, conduction properties, fibrosis, inflammation, molecule trafficking, and endothelial dysfunction. Interestingly, paroxysmal AF was not consistently associated with DE transcripts in any comparison. Principal component analysis of the expression of the 26 transcripts strongly associated with persistent AF did however reveal a distinct paroxysmal AF expression profile in-between no AF and persistent AF patients in the first principal component scores (Figure 1).

Conclusion

RNA sequencing of human atrial tissue samples identified many transcripts associated with persistent AF in left and/or right atria, discovered and replicated using two independent cohorts. These consistent findings of AF-induced changes provide a starting point for targeted proteomic analysis and single-nucleus sequencing to further unravel the molecular mechanisms underlying AF progression to persistent AF, and biomarker development to quantify AF progression and enable precision medicine in individual patients.

The role of the autonomous nervous system in atrial fibrillation progression. Data from the RACE V study

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): We acknowledge the support from the Netherlands Cardiovascular Research Initiative: an initiative with support of the Dutch Heart Foundation, CVON 2014-9: Reappraisal of Atrial Fibrillation: interaction between hyperCoagulability, Electrical remodelling, and Vascular destabilisation in the progression of AF (RACE V). Unrestricted grant support from Medtronic Trading NL B.V.

Background

Atrial fibrillation (AF) progression is associated with adverse outcome.

The autonomic nervous system plays a yet unsettled role in initiation and progression of AF.

Purpose

To assess in patients with paroxysmal selfterminating AF differences in phenotype and AF progression depending on the role of the autonomic nervous system in triggering AF episodes.

Methods

Patients with paroxysmal AF included in the Reappraisal of AF: Interaction Between HyperCoagulability, Electrical Remodelling, and Vascular Destabilisation in the Progression of AF (RACE V) study were analysed. Patients were extensively phenotyped at baseline and received continuous rhythm monitoring with an implantable loop recorder (ILR).To adequately define the role of the autonomic nervous system in triggering AF only patients with at least 3 selfterminating AF episodes were included. ILR data were used to assess whether AF was mainly vagally induced (&gt;80% of episodes starting during night time) or mainly adrenergically induced (&gt;80% starting during daytime), and to assess the development of AF progression. If a patient could not be identified as either vagal or adrenergic, they were classified as mixed AF. Primary outcome were differences in AF progression between the three groups. AF progression was defined as (1) progression to persistent or permanent AF, or (2) progression of PAF with &gt;3% burden increase. Follow-up was 2.2 (1.6-2.8) years.

Results

278 patients were included, median was age 66 (59-71) years, 117 (42%) were women (Table 1). Patients with vagally or adrenergically induced AF had less comorbidities compared to mixed AF patients (median 2 versus 2 versus 3, respectively, p=0.012). In the mixed group, compared to either the vagal or adrenergic group the estimated glomerular filtration rate was slightly worse (median 78 versus 84 versus 82 mL/min*1.73m2 in the mixed versus vagal and adrenergic group, respectively, p=0.018), diabetes was more common (12% versus 5% versus 0%, respectively, p=0.031). Obesity was most often present in the vagal group (38% versus 12% versus 27%, in the vagal versus adrenergic versus mixed group, respectively p=0.028). Progression rates in the vagal versus adrenergic versus mixed groups were 5% versus 5% versus 24%, respectively (p=0.013 vagal versus mixed and p=0.008 adrenergic versus mixed group, respectively)(Figure).

Conclusion

Important differences exist between AF patients depending on their autonomic nervous system associated triggering mechanisms. Patients with either vagally or adrenergically induced AF have less comorbidities as compared to those with a mixed initiation type of AF and showed lower AF progression rates.

The impact of a structured polygraphy screening incorporated in a novel remote mobile health pathway on sleep apnoea prevalence in patients with atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Background

Untreated obstructive sleep apnoea (OSA) contributes to progression of atrial fibrillation (AF) and reduces the success rate of heart rhythm control strategies. OSA remains one of the most frequently underdiagnosed modifiable risk factors in AF patients due to a lack of standardized screening methods and low awareness.

Purpose

To assess the impact of implementation of a structured remote OSA screening and management pathway on the prevalence of OSA in AF patients scheduled for AF ablation procedures.

Methods

In October 2020, a novel remote OSA screening and management pathway (VIRTUAL-SAFARI) was introduced in two AF outpatient clinics in the Netherlands. Consecutive patients scheduled for AF ablation were offered OSA screening consisting of sending a portable home sleep test to patients’ homes to perform a remote sleep recording for one night, analysis by a sleep physician, discussion of results with the patient, and initiation of treatment (when applicable). The impact of this structural screening strategy was assessed by comparing the prevalence of concomitant OSA (defined as apnoea-hypopnoea index ≥5) for patients scheduled for AF ablation in the year before and after introduction of the OSA management pathway.

Results

A total of 733 patients was studied, 308 in the year before (Oct ’19 - Sep ’20) and 425 in the year after (Oct ’20 - Sep ’21) introduction of the VIRTUAL-SAFARI pathway. Median age was 65 [58-71], 64% was male and median body mass index (BMI) was 27 [25-30] kg/m2. Baseline characteristics were comparable for the groups before and after introduction of the pathway (Table 1).

In the cohort before pathway introduction, OSA had been diagnosed in 26 patients (8%, Figure 1) and was treated with positive airway pressure in 10 cases (3%).

In the cohort after pathway introduction, OSA had previously been diagnosed in 53 patients (12%). Eighty-eight percent of patients without previous OSA screening was referred via the remote pathway. Results of the sleep recordings were available for 213 (59%) at the time of this analysis. Previously unknown OSA was diagnosed in 184 patients (86% of available recordings), increasing the prevalence of confirmed OSA to 237 (55%). For 22% of patients, results of sleep recordings are pending. Absence of OSA was confirmed in 9%, and 13% of patients had not been screened (e.g. because of patient preference or logistical reasons). After pathway introduction, 82 patients (19%) were treated or received advice to start treatment with positive airway pressure. Treatment decisions are pending for 9% of the cohort.

Conclusion

After the implementation of structured remote OSA screening in a well characterized cohort of consecutive patients scheduled for AF ablation, the prevalence of diagnosed OSA increased from 8% to 55%. Whether appropriate risk factor management, including treatment of OSA identified by structured screening, will improve AF outcomes needs to be tested in future studies.

The 3S-AF scheme, rather than the 4S-AF scheme, predicts progression in patients with paroxysmal atrial fibrillation: data from RACE V study

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): support from the Netherlands Cardiovascular Research Initiative: an initiative with support of the Dutch Heart Foundation, CVON 2014-9: Reappraisal of Atrial Fibrillation: interaction between hyperCoagulability, Electrical remodelling, and Vascular destabilisation in the progression of AF (RACE V).

Purpose

To assess whether the 4S-AF scheme predicts AF progression, cardiovascular hospitalizations and mortality in patients with self-terminating paroxysmal AF.

Methods

We analysed well-phenotyped patients with paroxysmal AF from the Reappraisal of Atrial Fibrillation: Interaction between HyperCoagulability, Electrical remodelling, and Vascular Destabilisation in the Progression of AF (RACE V study). From the 417 patients included in RACE V, 341 (82%) had echocardiography available. Patient had continuous monitoring with implantable loop recorders or pacemakers. Primary endpoint of RACE V was AF progression, defined as (1) progression to persistent or permanent AF, or (2) progression of PAF with &gt;3% burden increase. Median follow-up was 2.2 (1.6-2.8) years. Patients were given a score based on the components of the 4S-AF scheme (St, stroke=1; Sy, symptoms=2; Sb, Severity of burden=2; Su, Substrate=5) to a total maximum of 10 points (table 1). Left atrial fibrosis was not evaluated in our patients and therefore not included into the score. A score of zero (0) in the AF burden domain was given to all patients due to the presence of paroxysmal AF in all. A modified 4S-AF scheme was designed by eliminating the symptom domain, resulting in a 3S-AF scheme. Logistic regression was performed to assess AF progression and the composite endpoint of cardiovascular hospitalizations and mortality, C-statistic to assess prediction of the score, for both using the 4S-AF and the modified 3S-AF scheme.

Results

Mean age was 65 (IQR 58-71) years, 149 (44%) were women, 103 (48%) had heart failure (HFrEF 6 [2%]; HFpEF 97 [46%]), 276 (81%) had hypertension, 38(11%) had coronary artery disease and 162(48%) atherosclerosis (Table 2, Panel A). Based on the 4S-AF scheme, patients had an average score of 4.5±1.3, the majority had a score under 5 (n=272, 80%), 20% of the score was explained by the S1 domain (stroke), 16% of the score was explained by the Sy domain (symptoms), and 64% of the score was explained by the Su domain (substrate). The score points from the 4S-AF scheme did not predict the risk of AF progression (OR 1.08 95%CI 0.84 – 1.39, C-statistic 0.53) nor the composite endpoint (OR 0.79 95%CI 0.53 – 1.20, C-statistic 0.42, Table 2, Panel B). However, when excluding the Sy domain (symptoms) from the scheme, the 3S-AF scheme, it predicted the risk of progression (OR 1.54 95%CI 1.12 – 2.18, C-statistic 0.61, Table 2, Panel B).

Conclusion

In paroxysmal AF patients the 4S-AF scheme does not predict AF progression nor the composite endpoint cardiovascular hospitalizations and mortality. Although symptoms are important for choosing the treatment strategy, they may be less relevant to determine AF progression, cardiovascular hospitalization and mortality. To assess progression, the 3S-AF scheme may be more appropriate.

Atrial fibrillation and age synergistically increase clotting potential and promote atrial structural remodeling in goats

Funding Acknowledgements

Type of funding sources: Other. Main funding source(s): Netherlands Heart Foundation, European Union

Background

Age is a risk factor for atrial fibrillation (AF) as well as for stroke in patients with AF. However, the effect of ageing on AF mechanisms and on coagulation activity is not well understood.

Purpose

To evaluate the effect of age and AF on coagulation activity, AF characteristics, and atrial structural remodeling.

Methods

Four groups of female goats were investigated: Young sham (Y-Sh: sinus rhythm, &lt;3 years old, n=9), Young AF (Y-AF: 4 weeks of AF, &lt;3 years old, n=7), Old sham (O-Sh: sinus rhythm, &gt;8 years old, n=6), and Old AF (O-AF, 4 weeks of AF, &gt;8 years old, n=8). Groups were matched for body weight. AF was maintained using implantable pacemakers in both AF groups. Clotting potential, expressed as the ability of activated plasma to generate thrombin, was measured using tissue factor-induced thrombin generation assays at baseline and 4 weeks (final). A terminal experiment was performed with atrial contact mapping to study electrophysiological AF properties and to collect atrial tissue for histological analysis.

Results

Thrombin generation analysis showed that 4 weeks of AF induced a significant increase in clotting potential in old, but not in young goats. AF complexity and hemodynamics were not affected by age alone. AF, however, significantly increased the right atrial pressure in old (O-Sh: 6.4±1.9 vs. O-AF: 11.4±3.1 mmHg, p=0.02), but not in young goats. AF induced atrial myocyte hypertrophy and left atrial epicardial endomysial fibrosis in old goats, while this was not the case in young goats.

Conclusion

Four weeks of AF and advanced age synergistically enhanced coagulation potential and promoted atrial structural remodeling in goats. Complexity of atrial conduction was affected by AF, but not by age.

Optimization of a care pathway before atrial fibrillation ablation with the integration of translational research into routine clinical care

Funding Acknowledgements

Type of funding sources: None.

Background

The diagnostic work-up for atrial fibrillation (AF) catheter ablation is often complex and expensive. Improving the organization of this work-up may help to streamline patient journeys and to reduce administrative burden and costs. Additionally, reorganizing the existing work-up provides the opportunity to integrate (translational) research into routine clinical care, hereby contributing to improved patient selection and improved care for future patients.

Purpose

The aim of this project was to optimize a care pathway for patients considered for AF ablation, with the goals to improve the patient journey and simultaneously integrate research into the clinical process.

Methods

The Lean Six Sigma approach was used to map the pre-existing process, identify constraints in the process and formulate countermeasures. The impact of this pathway optimization was evaluated using four outcome measures: (1) efficient use of medical resources, defined as the percentage of patients receiving the pre-ablation work-up and eventually undergoing AF ablation, (2) number of hospital visits and consultations with a cardiologist, (3) pathway compliance, defined as the percentage of patients that completed the work-up with a maximum of 2 outpatient hospital visits, a maximum of 1 cardiologist consultation, laboratory results available, and a complete echocardiogram available, and (4) completeness of scientific data, defined as the availability of a predefined set of relevant variables (clinical indicators, medication, laboratory results and echocardiography derived data).

Results

Five root causes for constraints in the pre-existing work-up were identified and corresponding countermeasures were formulated (Figure 1). The impact of the countermeasures was studied for 33 patients before and 26 patients after pathway optimization. After optimization, efficient use of resources increased from 44% to 95% (p&lt;0.01). The project resulted in fewer hospital visits per patient (3.2 ±1.2 versus 2.3 ±0.8, p=0.01) and fewer cardiologist consultations (1.8 ±0.7 versus 1.0 ±0.3, p&lt;0.01). Pathway compliance increased significantly (3% versus 73%, p&lt;0.01), an increase that was reflected in all separate components of overall pathway compliance (Figure 2, panel A). The percentage of available data for scientific research increased from 80% to 94% (p&lt;0.01), resulting in a complete dataset in 73% of patients after, compared to only 15% of patients prior to the optimization project (p&lt;0.01, Figure 2, panel B).

Conclusions

This optimization project resulted in a more efficient care pathway for patients considered for AF ablation. The structural integration of research into the care pathway may lay the foundations for further improvements of AF care in the future.

High-density sequential mapping of repetitive atrial conduction patterns during atrial fibrillation

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work was supported by PersonalizeAF project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 860974.

Background

Localized AF drivers are considered candidate ablation targets for patients with persistent atrial fibrillation (AF). These drivers are expected to be associated with repetitive atrial conduction patterns during AF. Thus, tools that localize atrial sites with repetitive electrical activity might be instrumental in guiding ablation.

Purpose

High-density mapping catheters cover only a small portion of the atria. Combining sequential recordings from those catheters could provide a more complete picture of repetitive conduction patterns, and enable AF driver localization. We hypothesize that the repetitive activity generated by local AF drivers can be detected by means of high-coverage composite activation maps generated from spatially overlapping sequential recordings.

Methods

Repetitive conduction patterns were detected in a goat model of AF (249-electrode epicardial mapping array, 2.4mm inter-electrode distance, n=16) by exploiting recurrence plots (Fig 1A-C). Cross-recurrences of repetitive patterns in sequential recordings were detected in spatially overlapping recording locations. Using this information, local activation maps were aligned and combined into larger composite average activation maps (Fig. 1D-F). The proposed algorithm was tested on a dataset formed by segmenting the epicardial mapping area into four spatially overlapping regions. The proposed algorithm was then used to merge these segmented regions back together to reconstruct the original mapping area. Reconstruction accuracy was measured as the correlation between original and reconstructed average activation patterns (Fig. 2.). Statistical analyses were performed to investigate a possible relation between reconstruction accuracy and pattern properties such as duration, size, complexity, and cycle length. Patterns were classified as single peripheral, multiple waves, focal source, or re-entry based on the preferential conduction velocity directions.

Results

Among 1021 detected repetitive patterns, 328 spatiotemporally stable- patterns were present in all four artificially segmented recordings. In 32% of these, repetitiveness was associated with a local driver-either focal or re-entrant. Composite maps could be generated in 75% of the cases, and mainly in case of larger patterns (p&lt;0.01). The average correlation between the actual activation maps and the composite maps was 0.86 ±0.16. Only pattern duration showed a statistically significant low correlation with reconstruction accuracy of composite maps (r=0.126, p&lt;0.05). There was no significant difference in the reconstruction accuracy for multiple waves, focal sources and re-entries.

Conclusion(s)

The proposed framework could align sequentially recorded repetitive epicardial patterns over different atrial regions, to produce high-fidelity composite maps. The performance was minimally affected by pattern properties, thus suggesting potential use with a diverse range of AF patterns.

Atrial endomysial fibrosis is associated with sex, atrial fibrillation, heart failure and age in cardiac surgery patients: results from the Catch-Me consortium

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Horizon 2020

Background

Risk factors for atrial fibrillation (AF), such as ageing, heart failure and AF itself, enhance AF propensity partly by inducing atrial fibrosis. Atrial endomysial fibrosis, a type of reactive fibrosis occurring between cardiomyocytes, impairs transverse conduction in rapid atrial pacing animal models. The factors underlying transcriptional regulation of endomysial fibrosis are largely unknown.

Objective

To examine the contributions of age, sex, AF and heart failure to the development of endomysial fibrosis in the context of concurrent pathologies. To study genome-wide transcriptional changes associated with endomysial fibrosis in human left and right atrial appendage biopsies (LAA, n=95; RAA, n=76).

Methods

An algorithm for automated quantification of endomysial fibrosis following staining with wheat germ agglutinin (WGA) was employed. Linear mixed models were constructed to determine endomysial fibrosis quantity as a function of AF, heart failure, sex, age and four principal components that accounted for potential confounding effects of other clinical characteristics. RNA sequencing was used to study expression changes in the atrial transcriptome associated with endomysial fibrosis.

Results

Sex, persistent AF, heart failure and age were independently associated with endomysial fibrosis. We identified hundreds (LAA: 386, RAA: 311) of RNA transcripts associated with endomysial fibrosis. None of these associations were independent from the clinical phenotypes. However, explorative gene set enrichment analysis identified association of endomysial fibrosis with gene sets involved in extracellular matrix organization, immune response, cell motility, developmental processes, cardiac muscle contraction and proteostasis in LAA while in RAA only gene sets regulating contractile function were enriched.

Conclusion

Besides AF, female sex, age and heart failure are associated with endomysial fibrosis in the atria. While abundance of none of the differential genes were independently associated with endomysial fibrosis, gene set enrichment analysis suggests an involvement of extracellular matrix organization, immune response, cell motility, developmental processes and cardiac muscle contraction in endomysial fibrosis.

Performance of STOP-BANG questionnaire as sleep apnoea screening tool and development of a novel pre-selection model in patients with atrial fibrillation - insights from the Virtual-SAFARI study

Funding Acknowledgements

Type of funding sources: None.

Background

Sleep-disordered breathing (SDB) is highly prevalent in patients with atrial fibrillation (AF) and its screening is recommended in this population. The STOP-BANG questionnaire is widely used as SDB screening tool, but the subjective assessment of some of its parameters might limit its validity to detect SDB in AF patients.

Purpose

We assessed the performance of the STOP-BANG questionnaire to detect SDB with the use of a mobile health-based portable home sleep test given as reference in a cohort of AF patients. Moreover, we explored options to improve pre-selection for SDB screening in this cohort.

Methods

Consecutive AF patients who were referred for AF catheter ablation in two AF outpatient clinics and without previous history of SDB and/or SDB screening, were included prospectively. Patients characteristics together with STOP-BANG questionnaire were assessed at baseline visitation. STOP-BANG scores of 3-4 and 5-8 were interpreted as intermediate and high risk for SDB, respectively. All patients were digitally referred to a virtual SDB management pathway, independent of STOP-BANG score. Patients received a portable home sleep test to detect SDB, which patients used for one night at home after instructions. Sleep recordings were accessed by sleep physicians via a secured cloud and sleep reports were discussed with patients and referring physicians. Apnoea-hypopnoea-indexes (AHI) of &gt;=15 and of &gt;= 30 were interpreted as moderate-to-severe and severe SDB, respectively. Results of the STOP-BANG and the home sleep test were compared and performance of the STOP-BANG questionnaire was assessed. Uni- and multivariable logistic regression analyses based on patient characteristics were used to construct a nomogram to improve pre-selection for SDB screening in this cohort.

Results

A total of 156 patients (median age 65 years, 63.8% male) were included. According to results from the home sleep test, 53% of patients were diagnosed with moderate-to-severe SDB, including 16% with severe SDB. STOP-BANG questionnaire performed poorly with an area under the receiver operating characteristic curve (AUROC) of 0.661 and 0.684 in predicting moderate-to-severe and severe SDB, respectively. On multivariable logistic analysis, independent predictors for moderate-to-severe SDB were body-mass-index (BMI), age and apnoeas. A nomogram was built on this variables (Fig. 1), which performed good with an AUROC of 0.728 in predicting moderate-to-severe SDB.

Conclusion

In a cohort of AF patients scheduled for AF catheter ablation, SDB was highly prevalent. STOP-BANG questionnaire had poor value for the prediction of moderate-to-severe and severe SDB compared to a systematical SDB screening via home sleep test. Using STOP-BANG questionnaire as a pre-selection tool might lead to frequently undetected and untreated SDB. Whether the nomogram based on our analyses improves pre-selection for SDB screening in AF patients will be validated in a future cohort.

Advanced vascular aging in patients with paroxysmal atrial fibrillation - Data from RACE V

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Dutch Heart Foundation, Medtronic

Background

The incidence of atrial fibrillation (AF) increases exponentially with age. To which extend vascular aging is part of this process is unknown. Pulse wave velocity and carotid intima-media thickness are established markers for vascular aging and have been combined in a vascular aging index as published before(1).

Purpose

We aim to investigate if vascular age exceeds chronological age in our cohort with paroxysmal AF and if yes to which extend.

Methods

In this substudy from RACE V we included 295 patients with paroxysmal AF in which carotid-femoral pulse wave velocity (cfPWV) and carotid intima-media thickness (IMT) were measured. To calculate vascular aging we used a logarithmic formula derived from the Malmö-Cancer-and-Diet study which yields a vascular age index derived from cfPWV, cIMT and chronological age. This vascular aging index (VAI) is a strong predictor of cardiovascular events. (1). All patients underwent cardiac echocardiography and had a native cardiac CT scan in which fat around the heart and coronary calcium were quantified. In 121 patients Agatston scores from the ascending aortic artery were also measured.

Results

Patients in this study had a mean chronological age of 63.8 ± 10.1 years and a vascular age of 71.4 ± 11.7 years. Vascular age was on average 9.3 ± 10.2 years higher than chronological age. Vascular age correlated significantly with markers for diastolic dysfunction, vascular calcification in the coronary arteries as well as the aorta and the amount of epicardial and pericardial fat (table 1).

Conclusions

In patients with PAF vascular age was on average 9.3 years higher than chronological age in our cohort. Advanced vascular age is represented by vascular and myocardial remodeling related to fibrosis, calcification and fat accumulation. The results suggest that in patients with AF enhanced inflammation is leading to fibrosis and calcification. Whether AF is a marker, a mechanism or both in advanced vascular aging warrants further study.

The impact of different fat depots in the body on the progression of atrial fibrillation - data from RACE V

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Dutch Heart Foundation, Medtronic

Background

Paroxysmal atrial fibrillation (PAF) progression is associated with cardiovascular complications and worse outcome. Obesity is independently associated with AF prevalence and progression. The association between different fat depots in the body with AF is unclear.

Aim

We aim to systematically investigate the association of different fat depots in the body with AF.

Methods

417 patients with PAF and continuous rhythm monitoring (implantable loop recorder or pacemaker) were included in the prospective RACE V study. In addition to extensive phenotyping at baseline including calculating BMI and measuring waist circumference (WC) epicardial and pericardial fat were measured on non-contrast enhanced cardiac CT scans by tracing the pericardium manually on every slice and afterwards fat automatically summed between -50 and -150 HU. Epicardial fat was defined as fat within the pericardium, pericardial fat as fat inside the pericardium and adjacent to the pericardium and thoracic fat as adjacent fat outside the pericardium. AF progression was defined as (1) progression to persistent or permanent AF, or (2) progression of PAF with &gt;3% burden increase within 2.2years of follow-up. Multivariable logistic regression analysis was used to analyse the association of different fat pads with AF progression.

Results

Six percent of patients per year showed AF progression (51/417) after a median follow-up of 2.2 (1.6-2.8) years. Multivariate analysis identified WC (odds ratio [OR] 1.03, 95% confidence intervals [CI] 1.01-1.06, p=.014) to be associated with AF progression. Epicardial fat (OR 1.00, 95%CI .99-1.01, p=.407), pericardial fat (OR 1.00, 95%CI .99-1.01, p=.311), thoracic fat (OR 1.00, 95%CI .99-1.01, p=.372), and BMI (OR 1.03, 95%CI .97-1.10, p=.328) showed no relation with AF progression.

Conclusion

AF progression occurred in 6% per year in patients with PAF. In contrast to epicardial, pericardial and thoracic fat measured in a semiautomatic way, WC was the only fat depot associated with AF progression. Whether a more different assessment of obesity and epicardial fat may demonstrate an association with AF progression warrants further study.

BMP10 level helps to stratify risk of atrial fibrillation recurrence within one year after catheter ablation

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): DGK Electrophysiology grant

Background

Freedom of atrial fibrillation (AF) is the main purpose of catheter ablation. However, AF recurrence is commonly seen after catheter ablation. Cardiovascular biomarkers may help to identify patients at risk for AF recurrence.

Purpose

We investigated the association of preprocedural known and novel cardiovascular biomarker level with AF recurrence within one year after catheter ablation.

Methods

In 187 patients of the AFAB registry (University Maastricht, the Netherlands) clinical recurrence of AF after catheter ablation was investigated using Holter ECGs at 3- and 12-months follow-up. Blood samples taken before AF catheter ablation were analyzed for prediction of AF recurrence by known or novel cardiovascular biomarkers (FGF23, BMP10, Ang2, IGFBP7, CA125, NT-proBNP, TNT_hs, sFlt_1, ESM1_7F89A5, DKK3). Recurrence of AF was defined as any symptomatic, or ECG documented episode of AF within one year after catheter ablation. A logistic regression model adjusted for typical risk factors of AF recurrence (Sex, age, type of AF (paroxysmal or persistent), ongoing rhythm, LA diameter, heart failure, body mass index and hypertension) was calculated and receiver-operating analysis was performed for prediction of AF recurrence.

Results

AF recurrence was found in 86 patients within one year after catheter ablation. Elevated biomarker level in patients with AF recurrence were found for BMP10, Ang2, and NT-proBNP in univariate analysis (table 1). In the logistic regression BMP10 (Odds ratio 2.94, 95%CI 1.089-7.939, P=0.033) indicated a high probability of AF recurrence within one year. A model including factors of AF recurrence showed a predictability for AF recurrence of an area under the curve (AUC) of 0.68 (sensitivity 60%, specificity 64%). By adding each of the univariate significant biomarker the predictability of the model increases further Ang2 (AUC 0.69, sensitivity 69%, specificity 60%), NT-proBNP (AUC 0.69, sensitivity 65%, specificity 60%), and BMP10 (AUC 0.71, sensitivity 60%, specificity 73%).

Conclusions

Based on our data, Ang2, BMP10, NT-proBNP showed elevated values for patients with recurrence of AF within one year before catheter ablation. BMP10, which is likely associated with trabeculation of the heart, outperformed the other investigated known and novel biomarker indicating a higher probability of AF recurrence within one year after ablation.

Development and validation of a fully automatic algorithm to align 3D MRI and electro-anatomical mapping anatomies of the left atrium

Funding Acknowledgements

Type of funding sources: None.

Background

The role of pre-procedural cardiac imaging in the guidance and planning of ablation procedures is becoming increasingly important. Emerging non-invasive techniques such as late gadolinium enhancement magnetic resonance imaging (LGE MRI) and electrocardiographic imaging (ECGi) can potentially help to locate ablation targets prior to the ablation procedure. To be able to integrate LGE MRI and ECGi information into targeted ablation procedures, a reliable alignment between cardiac imaging and electro-anatomical mapping (EAM) is required.

Purpose

To develop and evaluate a fully automatic technique to align pre-procedural MRI anatomies with EAM anatomies of the left atrium (LA).

Methods

Twenty-one patients scheduled for a (re-do) pulmonary vein (PV) isolation with a 3D pre-procedural LGE MRI were enrolled in this study. LA anatomy was segmented from the MRI dataset using ADAS-AF. During the ablation procedure LA anatomy was recorded with an HD-grid (Ensite) or Pentaray catheter (CARTO). The MRI segmentation and EAM were performed by different cardiologists blinded for each other’s results. Anatomies of both MRI and EAM were aligned using an iterative closest point-to-plane algorithm in custom-made software in Matlab 2021a. With this algorithm, the distance between MRI anatomy voxels (=points) and the surface of the EAM anatomy (=plane) is minimized by translating and rotating the MRI anatomy until the total residual distance is minimized. The result of the alignment is quantified by calculating the Euclidian distance between the aligned anatomies after excluding PVs and the mitral anulus.

Results

The algorithm was successfully applied in 18/21 patients (n=11 CARTO, n=7 Ensite). In the remaining 3 patients, the algorithm could not align the anatomies because of a large difference in LA volume or PV anatomy between the two techniques. In the analysed patients, the average distance between anatomies was 2.7±0.77mm. The top of Figure 1 shows the alignment of the anatomies with the smallest (patient A) and the largest (patient B) residual distances as well as the distances between these anatomies for both patients (right) with purple ≤2.5mm and red ≥5.0mm. The distributions of distances (bottom left) show that, after alignment most of the MRI anatomy is closer than 5mm from the EAM anatomy in every patient. On average, 87.6±10.4% of the atrial surfaces showed distances below 5.0mm between the two anatomies and 55.1±13.2% of the surfaces was within 2.5mm from each other. Results did not differ between Ensite and CARTO anatomies.

Conclusion

LA anatomy obtained from 3D LGE MRI can automatically and reliably be aligned with LA anatomy recorded during an ablation procedure with an EAM system using an iterative closest point-to-plane algorithm.