Cardiac-specific overexpression of CREM-IbΔC-X via CRISPR/Cas9 in mice presents a new model of atrial cardiomyopathy with spontaneous atrial fibrillation

Atrial cardiomyopathy (ACM) forms the substrate for atrial fibrillation (AF) and underlies the potential for atrial thrombus formation and subsequent stroke. However, generating stable animal models that accurately replicate the entire progression of atrial lesions, particularly the onset of AF, presents significant challenges. In the present study, we found that the isoform of CRE-binding protein modulator (CREM-IbΔC-X), which is involved in the regulation of cardiac development and atrial rhythm, was highly expressed in atrial biopsies from patients with AF. Building upon this finding, we employed CRISPR/Cas9 technology to create a mouse model with cardiac-specific overexpression of CREM-IbΔC-X (referred to as CS-CREM mice). This animal model effectively illustrated the development of ACM through electrophysiological and structural remodelings over time. Proteomics and Chip-qPCR analysis of atrial samples revealed significant upregulation of cell-matrix adhesion and extracellular matrix structural components, alongside significant downregulation of genes related to atrial functions in the CS-CREM mice. Furthermore, the corresponding responses to anti-arrhythmia drugs, i.e., amiodarone and propafenone, suggested that CS-CREM mice could serve as an ideal in vivo model for drug testing. Our study introduced a novel ACM model with spontaneous AF by cardiac-specifically overexpressing CREM-IbΔC-X in mice, providing valuable insights into the mechanisms and therapeutic targets of ACM.

Atrial Cardiomyopathy Predicts the Functional Outcome and Mortality in Stroke Patients

AIM

Atrial cardiomyopathy (ACM) is characterized by atrial dysfunction. This study aims to assess the prognostic significance of ACM in patients with noncardioembolic stroke (NCS).

METHODS

Patients with NCS within seven days of onset were prospectively enrolled between January 2019 and December 2020. ACM was defined as either an N-terminal pro-brain natriuretic peptide (NT-pro BNP) ＞250 pg/ml or a P-terminal force in precordial lead V1 (PTFV1) ≥ 5000µV·ms. A poor functional outcome was determined as a score of 3-6 on the modified Rankin Scale (mRS) within a 2-year follow-up period. Logistic regression and Cox regression analyses were employed to examine the relationship between ACM and the long-term prognosis of patients with NCS.

RESULTS

A total of 1,346 patients were enrolled, of whom 299 (22.2%) patients were diagnosed with ACM. A total of 207(15.4%) patients experienced a poor functional outcome, and 58 (4.3%) patients died. A multivariate logistic regression analysis indicated that ACM was significantly associated with a poor functional outcome in NCS patients [adjusted odds ratio (aOR): 2.01; 95% confidence interval (CI): 1.42-2.87; p＜0.001]. Additionally, a multivariate Cox regression analysis showed that an NT-pro BNP ＞250 pg/ml was significantly associated with an increased risk of all-cause mortality [adjusted hazard ratio (aHR), 2.51; 95% CI: 1.42-4.43; p=0.001].

CONCLUSIONS

ACM may serve as a novel predictor of a poor long-term functional outcome in patients with NCS. Elevated NT-pro BNP levels (＞250 pg/ml) were found to be associated with a higher risk of all-cause mortality. These findings warrant further validation in multicenter studies.

Left atrial cardiomyopathy: Pathophysiological insights, assessment methods and clinical implications

Atrial cardiomyopathy is defined as any complex of structural, architectural, contractile or electrophysiological changes affecting atria, with the potential to produce clinically relevant manifestations. Most of our knowledge about the mechanistic aspects of atrial cardiomyopathy is derived from studies investigating animal models of atrial fibrillation and atrial tissue samples obtained from individuals who have a history of atrial fibrillation. Several noninvasive tools have been reported to characterize atrial cardiomyopathy in patients, which may be relevant for predicting the risk of incident atrial fibrillation and its related outcomes, such as stroke. Here, we provide an overview of the pathophysiological mechanisms involved in atrial cardiomyopathy, and discuss the complex interplay of these mechanisms, including aging, left atrial pressure overload, metabolic disorders and genetic factors. We discuss clinical tools currently available to characterize atrial cardiomyopathy, including electrocardiograms, cardiac imaging and serum biomarkers. Finally, we discuss the clinical impact of atrial cardiomyopathy, and its potential role for predicting atrial fibrillation, stroke, heart failure and dementia. Overall, this review aims to highlight the critical need for a clinically relevant definition of atrial cardiomyopathy to improve treatment strategies.

Prognostic impact of atrial cardiomyopathy: Long-term follow-up of patients with and without low-voltage areas following atrial fibrillation ablation

BACKGROUND

Atrial cardiomyopathy is known as an underlying pathophysiological factor in the majority of patients with atrial fibrillation (AF). Left atrial low-voltage areas (LVAs) are reported to coincide with fibrosis and likely represent atrial cardiomyopathy.

OBJECTIVE

The purpose of this study was to delineate differences in the long-term prognosis of patients stratified by the size of LVAs.

METHODS

This observational study included 1488 consecutive patients undergoing initial ablation for AF. LVAs were defined as regions with a bipolar peak-to-peak voltage <0.50 mV. The total study population was divided into 3 groups stratified by LVA size: patients with no LVAs (n = 1136); those with small (<20 cm2) LVAs (n = 250) LVAs; and those with extensive (≥20 cm2) LVAs (n = 102). Composite endpoints of death, heart failure, and stroke were followed for up to 5 years.

RESULTS

Composite endpoints developed in 105 of 1488 patients (7.1%), and AF recurrence occurred in 410 (27.6%). Composite endpoints developed more frequently in the order of patients with extensive LVAs (19.1%), small LVAs (10.8%), and no LVAs (5.1%) (P for trend <.0001). Multivariable analysis revealed that LVA presence was independently associated with higher incidence of composite endpoints, irrespective of AF recurrence (modified hazard ratio 1.73; 95% confidence interval 1.13-2.64; P = .011) CONCLUSION: LVA presence and its extent both were associated with poor long-term composite endpoints of death, heart failure, and stroke, irrespective of AF recurrence or other confounders. Underlying atrial cardiomyopathy seems to define a poor prognosis after AF ablation.

Optimizing fibrosis detection: a comparison of electroanatomical mapping and late enhancement gadolinium magnetic resonance imaging

BACKGROUND

Fibrotic atrial cardiomyopathy plays an important role in determining the outcome of ablation in patients with atrial fibrillation (AF). Two main methods are being used for the evaluation of fibrosis: voltage-based high-density (HD) electroanatomical mapping (EAM) and late gadolinium enhancement MRI (LGE-MRI). The comparability between both methods in detecting fibrosis has not been systematically investigated.

METHODS

LGE-MRIs of the left atrium (LA) were performed in 21 patients. LA-fibrosis was evaluated using a custom-designed software generating a 3D-model of the LA. HD-electroanatomical maps were recorded in each patient. After processing the maps and the MRI models by excluding the mitral valve, pulmonary veins, and the left atrial appendage, the LGE areas were measured and compared to the low voltage areas (LVA) in the HD maps using three different cutoff values of 0.5 mV, 0.7 mV, and 1.0 mV.

RESULTS

The analysis revealed significant differences between EAM and LGE-MRI in assessing LA-fibrosis at 0.5-mV (for anterior and posterior walls) and 1.0-mV cutoffs (for anterior and posterior wall and septum). However, no significant differences were found between EAM and LGE-MRI when using a 0.7-mV cutoff for all the investigated areas.

CONCLUSIONS

A voltage cutoff of 0.7 mV provided the best correlation between EAM and LGE MRI for detecting left atrial fibrosis. It supports the idea that a 0.5-mV cutoff may underestimate fibrosis, as areas with local signal voltages between 0.6 and 0.8 mV could also show LGE on MRI. Further research is needed to determine the ideal voltage cutoff for detecting left atrial fibrosis.

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.

Practical approach for atrial cardiomyopathy characterization in patients with atrial fibrillation

Atrial fibrillation (AF) causes progressive structural and electrical changes in the atria that can be summarized within the general concept of atrial remodeling. In parallel, other clinical characteristics and comorbidities may also affect atrial tissue properties and make the atria susceptible to AF initiation and its long-term persistence. Overall, pathological atrial changes lead to atrial cardiomyopathy with important implications for rhythm control. Although there is general agreement on the role of the atrial substrate for successful rhythm control in AF, the current classification oversimplifies clinical management. The classification uses temporal criteria and does not establish a well-defined strategy to characterize the individual-specific degree of atrial cardiomyopathy. Better characterization of atrial cardiomyopathy may improve the decision-making process on the most appropriate therapeutic option. We review current scientific evidence and propose a practical characterization of the atrial substrate based on 3 evaluation steps starting with a clinical evaluation (step 1), then assess outpatient complementary data (step 2), and finally include information from advanced diagnostic tools (step 3). The information from each of the steps or a combination thereof can be used to classify AF patients in 4 stages of atrial cardiomyopathy, which we also use to estimate the success on effective rhythm control.

Left atrial strain: A memory of the severity of atrial myocardial stress in atrial fibrillation

BACKGROUND

Left atrial (LA) strain is a simple marker of LA function. The aim of the study was to evaluate the determinants of atrial cardiomyopathy in AF.

METHODS

In this pilot study, we prospectively evaluated clinical, biological, metabolomic and echocardiographic parameters for 85 consecutive patients hospitalized for atrial fibrillation (AF) with restoration of sinus rhythm at 6 months. Eighty-one patients with an analysable LA strain at 6 months were divided into groups according to median reservoir strain:<23.3% (n=40) versus≥23.3% (n=41).

RESULTS

Compared to patients with the highest LA strain, patients with lowest LA strain had multiple differences at admission: clinical (older age; more frequent history of AF; more patterns of persistent AF); biological (higher fasting blood glucose levels, glycated haemoglobin, high-sensitivity C-reactive protein, and urea; lower glomerular filtration rate); metabolomic (higher levels of kynurenine, kynurenine/tryptophan, and urea/creatinine; lower levels of arginine and methionine/methionine sulfoxide); and echocardiographic (higher two-dimensional end-systolic LA volume [LAV] indexes; higher three-dimensional end-systolic and end-diastolic LAV and right atrial volume indexes; lower LA and right atrial emptying fractions and three-dimensional right ventricular ejection fraction) (all P<0.05). Area under the receiver operating characteristic curve to predict LA strain alteration at 6 months was highest for a combined score including clinical, biological, metabolomic and echocardiographic variables at admission (area under the receiver operating characteristic curve 0.871; P<0.0001).

CONCLUSIONS

LA reservoir strain could be a memory of initial atrial myocardial stress in AF. It can be predicted using a combination of clinical, biological, metabolomic and echocardiographic admission variables.

Detection of subclinical atrial fibrillation with cardiac implanted electronic devices: What decision making on anticoagulation after the NOAH and ARTESiA trials?

Atrial fibrillation (AF) may be asymptomatic and the extensive monitoring capabilities of cardiac implantable electronic devices (CIEDs) revealed asymptomatic atrial tachi-arrhythmias of short duration (minutes-hours) occurring in patients with no prior history of AF and without AF detection at a conventional surface ECG. Both the terms "AHRE" (Atrial High-Rate Episodes) and subclinical AF were used in a series of prior studies, that evidenced the association with an increased risk of stroke. Two randomized controlled studies were planned in order to assess the risk-benefit profile of anticoagulation in patients with AHRE/subclinical AF: the NOAH and ARTESiA trials. The results of these two trials (6548 patients enrolled, overall) show that the risk of stroke/systemic embolism associated with AHRE/subclinical AF is in the range of 1-1.2 % per patient-year, but with an important proportion of severe/fatal strokes occurring in non-anticoagulated patients. The apparent discordance between ARTESiA and NOAH results may be approached by considering the related study-level meta-analysis, which highlights a consistent reduction of ischemic stroke with oral anticoagulants vs. aspirin/placebo (relative risk [RR] 0.68, 95 % CI 0.50-0.92). Oral anticoagulation was found to increase major bleeding (RR 1.62, 95 % CI 1.05-2.5), but no difference was found in fatal bleeding (RR 0.79, 95 % CI 0.37-1.69). Additionally, no difference was found in cardiovascular death or all-cause mortality. Taking into account these results, clinical decision-making for patients with AHRE/subclinical AF at risk of stroke, according to CHA2DS2-VASc, can now be evidence-based, considering the benefits and related risks of oral anticoagulants, to be shared with appropriately informed patients.

Clinical presentation, management, and survival in dogs with persistent atrial standstill in the United Kingdom

OBJECTIVES

To investigate the clinical and echocardiographic presentation of dogs with persistent atrial standstill (PAS), identify variables measured at first presentation that could predict their survival, and document the progression of the disease after pacing.

MATERIALS AND METHODS

Retrospective study of medical records of dogs diagnosed with PAS at three referral hospitals of the United Kingdom over seven years.

RESULTS

Twenty-six dogs were diagnosed with PAS during the study period. Median age of the population was three years (range: 7 months-12.5 years). The most common clinical sign was syncope (14/26). Twenty-four dogs received artificial pacemakers (PM). Major complications after PM implantation were observed in four dogs (4/24). Serial echocardiographic examinations showed that cardiac dimensions of PAS dogs with left atrial or left ventricular dilation at first presentation did not return to reference range after pacing. Further dilation of the cardiac chambers, recurrence of congestive heart failure (CHF), or development of new episodes of CHF were documented in 7, 4, and 10 PAS dogs, respectively, despite pacing. Median survival time for cardiac-related deaths after PM implantation was 1512 days (18-3207). Neither CHF nor echocardiographic variables at presentation predicted survival after PM implantation in PAS dogs.

CONCLUSIONS

PAS is an uncommon bradyarrhythmia, occurring in young adult dogs. Affected dogs were often presented with syncope. Whilst syncope resolved, cardiac remodeling persisted after PM implantation. Long-term survival was favorable after PM implantation and was not predicted by congestive status or cardiac chamber size at first presentation.

Magnetic resonance detection of advanced atrial cardiomyopathy increases the risk for atypical atrial flutter occurrence following atrial fibrillation ablation

AIMS

Recurrence of arrhythmia after catheter ablation of atrial fibrillation (AF) in the form of atypical atrial flutter (AFL) is common among a significant number of patients and often requires redo ablation with limited success rates. Identifying patients at high risk of AFL after AF ablation could aid in patient selection and personalized ablation approach. The study aims to assess the relationship between pre-existing atrial cardiomyopathy and the occurrence of AFL following AF ablation.

METHODS AND RESULTS

We analysed a cohort of 1007 consecutive AF patients who underwent catheter ablation and were included in a prospective registry. Patients who did not have baseline cardiac magnetic resonance imaging and late gadolinium enhancement (LGE-CMR) or did not experience any recurrences were excluded. A total of 166 patients were included gathering 56 patients who underwent re-ablation due to AFL recurrences and 110 patients who underwent re-ablation due to AF recurrences (P = 0.11). A multiparametric assessment of atrial cardiomyopathy was based on basal LGE-CMR, including left atrial (LA) volume, LA sphericity, and global and segmental LA fibrosis using semiautomated post-processing software. Out of the initial cohort of 1007 patients, AFL and AF occurred in 56 and 110 patients, respectively. An age higher than 65 [odds ratio (OR) = 5.6, 95% confidence interval (CI): 2.2-14.4], the number of previous ablations (OR = 3.0, 95% CI: 1.2-7.8), and the management of ablation lines in the index procedure (OR = 2.5, 95% CI: 1.0-6.3) were independently associated with AFL occurrence. Furthermore, several characteristics assessed by LGE-CMR were identified as independent predictors of AFL recurrence after the index ablation for AF, such as enhanced LA sphericity (OR = 1.3, 95% CI: 1.1-1.6), LA global fibrosis (OR = 1.03, 95% CI: 1.01-1.07), and increased fibrosis in the lateral wall (OR = 1.03, 95% CI: 1.01-1.04).

CONCLUSION

Advanced atrial cardiomyopathy assessed by LGE-CMR, such as increased LA sphericity, global LA fibrosis, and fibrosis in the lateral wall, is independently associated with arrhythmia recurrence in the form of AFL following AF ablation.

Differences in atrial substrate localization using late gadolinium enhancement-magnetic resonance imaging, electrogram voltage, and conduction velocity: a cohort study using a consistent anatomical reference frame in patients with persistent atrial fibrillation

AIMS

Electro-anatomical voltage, conduction velocity (CV) mapping, and late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) have been correlated with atrial cardiomyopathy (ACM). However, the comparability between these modalities remains unclear. This study aims to (i) compare pathological substrate extent and location between current modalities, (ii) establish spatial histograms in a cohort, (iii) develop a new estimated optimized image intensity threshold (EOIIT) for LGE-MRI identifying patients with ACM, (iv) predict rhythm outcome after pulmonary vein isolation (PVI) for persistent atrial fibrillation (AF).

METHODS AND RESULTS

Thirty-six ablation-naive persistent AF patients underwent LGE-MRI and high-definition electro-anatomical mapping in sinus rhythm. Late gadolinium enhancement areas were classified using the UTAH, image intensity ratio (IIR >1.20), and new EOIIT method for comparison to low-voltage substrate (LVS) and slow conduction areas <0.2 m/s. Receiver operating characteristic analysis was used to determine LGE thresholds optimally matching LVS. Atrial cardiomyopathy was defined as LVS extent ≥5% of the left atrium (LA) surface at <0.5 mV. The degree and distribution of detected pathological substrate (percentage of individual LA surface are) varied significantly (P < 0.001) across the mapping modalities: 10% (interquartile range 0-14%) of the LA displayed LVS <0.5 mV vs. 7% (0-12%) slow conduction areas <0.2 m/s vs. 15% (8-23%) LGE with the UTAH method vs. 13% (2-23%) using IIR >1.20, with most discrepancies on the posterior LA. Optimized image intensity thresholds and each patient's mean blood pool intensity correlated linearly (R2 = 0.89, P < 0.001). Concordance between LGE-MRI-based and LVS-based ACM diagnosis improved with the novel EOIIT applied at the anterior LA [83% sensitivity, 79% specificity, area under the curve (AUC): 0.89] in comparison to the UTAH method (67% sensitivity, 75% specificity, AUC: 0.81) and IIR >1.20 (75% sensitivity, 62% specificity, AUC: 0.67).

CONCLUSION

Discordances in detected pathological substrate exist between LVS, CV, and LGE-MRI in the LA, irrespective of the LGE detection method. The new EOIIT method improves concordance of LGE-MRI-based ACM diagnosis with LVS in ablation-naive AF patients but discrepancy remains particularly on the posterior wall. All methods may enable the prediction of rhythm outcomes after PVI in patients with persistent AF.

Interrelations between albuminuria, electrocardiographic left atrial abnormality, and incident atrial fibrillation in the Multi-Ethnic Study of Atherosclerosis (MESA) cohort

BACKGROUND

The objective of the study was to examine the joint associations of albuminuria and electrocardiographic left atrial abnormality (ECG-LAA) with incident atrial fibrillation (AF) and whether this relationship varies by race.

METHODS

This analysis included 6670 participants free of clinical cardiovascular disease (CVD), including atrial fibrillation (AF), from the Multi-Ethnic Study of Atherosclerosis. ECG-LAA was defined as P-wave terminal force in V1 [PTFV1] >5000 μV × ms. Albuminuria was defined as urine albumin-creatinine ratio (UACR) ≥30 mg/g. Incident AF events through 2015 were ascertained from hospital discharge records and study-scheduled electrocardiograms. Cox proportional hazard models were used to examine the association of "no albuminuria + no ECG-LAA (reference)", "isolated albuminuria", "isolated ECG-LAA" and "albuminuria + ECG-LAA" with incident AF.

RESULTS

Over a median follow-up of 13.8 years, 979 incident cases of AF occurred. In adjusted models, the concomitant presence of ECG-LAA and albuminuria was associated with a higher risk of AF than either ECG-LAA or albuminuria in isolation (HR (95% CI): 2.43 (1.65-3.58), 1.33 (1.05-1.69), and 1.55 (1.27-1.88), respectively (interaction p-value = 0.50). Effect modification by race was observed with a 4-fold greater AF risk in Black participants with albuminuria + ECG-LAA (HR (95%CI): 4.37 (2.38-8.01) but no significant association in White participants (HR (95% CI) 0.60 (0.19-1.92) respectively; (interaction p-value for race x albuminuria-ECG-LAA combination = 0.05).

CONCLUSIONS

Concomitant presence of ECG-LAA and albuminuria confers a higher risk of AF compared to either one in isolation with a stronger association in Blacks than Whites.

Atrial cardiomyopathy and incident ischemic stroke risk: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Growing evidence suggests that atrial cardiomyopathy may play an essential role in thrombosis and ischemic stroke. The aim of this systematic review and meta-analysis was to quantify the values of cardiomyopathy markers for predicting ischemic stroke risk.

METHODS

PubMed, Embase, and the Cochrane Library were searched for longitudinal cohort studies evaluating the association between cardiomyopathy markers and incident ischemic stroke risk.

RESULTS

We included 25 cohort studies examining electrocardiographic, structural, functional, and serum biomarkers of atrial cardiomyopathy involving 262,504 individuals. P-terminal force in the precordial lead V1 (PTFV1) was found to be an independent predictor of ischemic stroke as both a categorical variable (HR 1.29, CI 1.06-1.57) and a continuous variable (HR 1.14, CI 1.00-1.30). Increased maximum P-wave area (HR 1.14, CI 1.06-1.21) and mean P-wave area (HR 1.12, CI 1.04-1.21) were also associated with an increased risk of ischemic stroke. Left atrial (LA) diameter was independently associated with ischemic stroke as both a categorical variable (HR 1.39, CI 1.06-1.82) and a continuous variable (HR 1.20, CI 1.06-1.35). LA reservoir strain independently predicted the risk of incident ischemic stroke (HR 0.88, CI 0.84-0.93). N-terminal pro-brain natriuretic peptide (NT-proBNP) was also associated with incident ischemic stroke risk, both as a categorical variable (HR 2.37, CI 1.61-3.50) and continuous variable (HR 1.42, CI 1.19-1.70).

CONCLUSION

Atrial cardiomyopathy markers, including electrocardiographic markers, serum markers, LA structural and functional markers, can be used to stratify the risk of incident ischemic stroke.

Myosin light-chain 4 gene-transfer attenuates atrial fibrosis while correcting autophagic flux dysregulation

OBJECTIVES

To determine the role of MYL4 regulation of lysosomal function and its disturbance in fibrotic atrial cardiomyopathy.

BACKGROUND

We have previously demonstrated that the atrial-specific essential light chain protein MYL4 is required for atrial contractile, electrical, and structural integrity. MYL4 mutation/dysfunction leads to atrial fibrosis, standstill, and dysrhythmia. However, the underlying pathogenic mechanisms remain unclear.

METHODS AND RESULTS

Rats subjected to knock-in of a pathogenic MYL4 mutant (p.E11K) developed fibrotic atrial cardiomyopathy. Proteome analysis and single-cell RNA sequencing indicate enrichment of autophagy pathways in mutant-MYL4 atrial dysfunction. Immunofluorescence and electron microscopy revealed undegraded autophagic vesicles accumulated in MYL4p.E11K rat atrium. Next, we identified that dysfunctional MYL4 protein impairs autophagy flux in vitro and in vivo. Cardiac lysosome positioning and mobility were regulated by MYL4 in cardiomyocytes, which affected lysosomal acidification and maturation of lysosomal cathepsins. We then examined the effects of MYL4 overexpression via adenoviral gene-transfer on atrial cardiomyopathy induced by MYL4 mutation: MYL4 protein overexpression attenuated atrial structural remodeling and autophagy dysfunction.

CONCLUSIONS

MYL4 regulates autophagic flux in atrial cardiomyocytes via lysosomal mobility. MYL4 overexpression attenuates MYL4 p.E11K induced fibrotic atrial cardiomyopathy, while correcting autophagy and lysosomal function. These results provide a molecular basis for MYL4-mutant induced fibrotic atrial cardiomyopathy and identify a potential biological-therapy approach for the treatment of atrial fibrosis.

The association between C-peptide and atrial cardiomyopathy in nondiabetic adults: results from NHANES III

Serum C-peptide exhibits various biological activities. The relationship between C-peptide and atrial cardiomyopathy remains unknown. We aimed to investigate the association between C-peptide level and atrial cardiomyopathy in nondiabetic adults. Our study enrolled 4578 participants without diagnosed diabetes from the Third National Health and Nutrition Examination Survey (NHANES III). Atrial cardiomyopathy was defined as a deep terminal negative P wave in V1 below - 100 µV (more negative), according to the electrocardiogram. The participants were categorized into low C-peptide (≤ 1.46 nmol/L) and high C-peptide (> 1.46 nmol/L) groups, according to the receiver operating characteristic analysis. Odds ratio (OR) and 95% confidence interval (CI) for the association between C-peptide level and atrial cardiomyopathy were generated using multivariate logistic regression analysis. The prevalence of atrial cardiomyopathy was higher in the high C-peptide group than in the low C-peptide group (5.62% vs. 2.31%, P < 0.001, respectively). Multivariate logistic regression analysis showed that participants in the high C-peptide group had a 3.60-fold (95% CI 1.81-6.99) higher risk of atrial cardiomyopathy than those in the low C-peptide group. Per standard deviation increase in C-peptide was linked to a 1.20-fold (95% CI 1.00-1.41) higher risk in atrial cardiomyopathy. High C-peptide level might be an independent risk factor for atrial cardiomyopathy in nondiabetic adults.

Atrial cardiomyopathy: Diagnosis, clinical implications and unresolved issues in anticoagulation therapy

Atrial cardiomyopathy (AC) is an evolving pathophysiological entity that has expanded our understanding regarding the atrium and its role in arrhythmogenesis and cardiac thromboembolism. The pathological myocardium in AC promotes arrhythmogenesis through mechanical dysfunction (hypocontractility, fibrosis), adverse alterations of the endothelium and secretion of prothrombotic factors (IL-6, IL-8, TNF-a). 'Red flags', indicative of AC, can be recognized either non-invasively by electrocardiography, echocardiography and cardiac magnetic resonance imaging or invasively by high-density electroanatomical mapping as low bipolar voltage areas of the affected myocardium. Signs of AC have been strongly associated with an increased risk of ischemic stroke, even embolic strokes of undetermined source, regardless of the coexistence of atrial fibrillation (AF). The underlying existence of AC has been negatively correlated with the success rate of catheter ablation of AF. The clinical value of AC is the provision of a novel pathway regarding the potential mechanisms of cerebrovascular events of cardiac thromboembolic origin. In addition, AC may serve as a risk stratification tool to predict the long-term responders of AF catheter ablation.

Impacts of a high-fat diet on the metabolic profile and the phenotype of atrial myocardium in mice

AIMS

Obesity, diabetes, and metabolic syndromes are risk factors of atrial fibrillation (AF). We tested the hypothesis that metabolic disorders have a direct impact on the atria favouring the formation of the substrate of AF.

METHODS AND RESULTS

Untargeted metabolomic and lipidomic analysis was used to investigate the consequences of a prolonged high-fat diet (HFD) on mouse atria. Atrial properties were characterized by measuring mitochondria respiration in saponin-permeabilized trabeculae, by recording action potential (AP) with glass microelectrodes in trabeculae and ionic currents in myocytes using the perforated configuration of patch clamp technique and by several immuno-histological and biochemical approaches. After 16 weeks of HFD, obesogenic mice showed a vulnerability to AF. The atrial myocardium acquired an adipogenic and inflammatory phenotypes. Metabolomic and lipidomic analysis revealed a profound transformation of atrial energy metabolism with a predominance of long-chain lipid accumulation and beta-oxidation activation in the obese mice. Mitochondria respiration showed an increased use of palmitoyl-CoA as energy substrate. APs were short duration and sensitive to the K-ATP-dependent channel inhibitor, whereas K-ATP current was enhanced in isolated atrial myocytes of obese mouse.

CONCLUSION

HFD transforms energy metabolism, causes fat accumulation, and induces electrical remodelling of the atrial myocardium of mice that become vulnerable to AF.

New concepts in atrial fibrillation pathophysiology

The current classification of atrial fibrillation (AF) is mainly focused on the clinical presentation according to the duration of AF episodes and the mode of termination, which incompletely reflect the severity and progressive nature of the underlying atrial disease. In this review article, "atrial cardiomyopathy" is discussed as a new concept in AF pathophysiology. Electrogram-, imaging-, and biomarker-derived measures and parameters to assess atrial cardiomyopathy, which will likely impact how AF is clinically classified and managed in the future, are presented.

Atrial Fibrillation, thromboembolic risk, and the potential role of the natriuretic peptides, a focus on BNP and NT-proBNP - A narrative review

Atrial fibrillation (AF) is one of the most commonly encountered arrythmia in clinical practice. AF itself can be driven by genetic predisposition, ectopic electrical activity, and abnormal atrial tissue substrates. Often there is no single etiological mechanism, but rather a combination of factors that feed back to remodel and worsen tissue substrate, "AF begets AF". The clinical consequences of AF can often include emboli, heart failure, and early mortality. The classical AF cardioembolic (CE) concept requires thrombus formation in the left atrial appendage, with subsequent embolization. The temporal dissociation between AF occurrence and CE events has thrown doubt on AF as the driver of this mechanism. Instead, there has been a resurgence of the "atrial cardiomyopathy" (ACM) concept. An ACM is proposed as a potential mechanism of embolic disease through promotion of prothrombotic mechanisms, with AF instead reflecting atrial disease severity. Regardless, AF has been implicated in 25% to 30% of cryptogenic strokes. Natriuretic peptide(NP)s have been shown to be elevated in AF, with higher levels of both NT-proBNP and BNP being predictive of incidental AF. NPs potentially reflect the atrial environment and could be used to identify an underlying ACM. Therefore, this narrative review examines this evidence and mechanisms that may underpin the role of NPs in identifying atrial dysfunction, with focus on both, BNP and NTproBNP. We explore their potential role in the prediction and screening for both, ACM and AF. Moreover, we compare both NPs directly to ascertain a superior biomarker.

Left atrial echocardiographic parameters predict the onset of atrial fibrillation: the SMASH2 scoring system

BACKGROUND

As AF-associated morbidity and mortality are increasing, there is an acute need for improved surveillance and prevention strategies to reduce the impact of AF and related strokes. Specific echocardiographic parameters that can best predict future onset of AF within 3 months are lacking.

METHODS

Twenty patients with AF, as identified by presence of ICD-9 diagnosis code, were compared with a control group of twenty age- and sex-matched patients selected from the same clinic population but without a diagnosis of AF. Transthoracic echocardiograms (TTE) obtained within 90 days prior to first documented AF episode (study group) or obtained closest to first clinic visit (control) were selected for review.

RESULTS

Baseline characteristics, including age, BMI, presence of hypertension, hyperlipidemia, diabetes, and heart failure were comparable. Increased left atrial (LA) size (end systolic major axis in 2-chamber view: AF 4.62±0.03 vs control 3.79±0.21, P =0.03), increased mitral inflow (E/A ratio: AF 1.35±0.15 vs control 1.06±0.07, P =0.04), and reduced LA global longitudinal strain (AF -2.69±0.26 vs control - 3.59±0.31, P =0.04) were most closely associated with AF compared with the control group. Multivariate logistic regression was used to develop predictive models for AF onset. A combination of imaging and traditional clinical risk factors was the best AF prediction model with AUC of 0.94, which greatly exceeds the current best predictors published. From these parameters, we developed the SMASH2 scoring system for 90- day AF risk estimation.

CONCLUSIONS

Risk factors for AF and early features of atrial cardiomyopathy including male sex, hypertension, LA enlargement, reduced mitral inflow, and reduced LA strain are powerful predictors of AF onset within 90 days, and may be used to prognosticate future AF risk.

Atrial cardiomyopathy: from cell to bedside

Atrial cardiomyopathy refers to structural and electrical remodelling of the atria, which can lead to impaired mechanical function. While historical studies have implicated atrial fibrillation as the leading cause of cardioembolic stroke, atrial cardiomyopathy may be an important, underestimated contributor. To date, the relationship between atrial cardiomyopathy, atrial fibrillation, and cardioembolic stroke remains obscure. This review summarizes the pathogenesis of atrial cardiomyopathy, with a special focus on neurohormonal and inflammatory mechanisms, as well as the role of adipose tissue, especially epicardial fat in atrial remodelling. It reviews the current evidence implicating atrial cardiomyopathy as a cause of embolic stroke, with atrial fibrillation as a lagging marker of an increased thrombogenic atrial substrate. Finally, it discusses the potential of antithrombotic therapy in embolic stroke with undetermined source and appraises the available diagnostic techniques for atrial cardiomyopathy, including imaging techniques such as echocardiography, computed tomography, and magnetic resonance imaging as well as electroanatomic mapping, electrocardiogram, biomarkers, and genetic testing. More prospective studies are needed to define the relationship between atrial cardiomyopathy, atrial fibrillation, and embolic stroke and to establish a prompt diagnosis and specific treatment strategies in these patients with atrial cardiomyopathy for the secondary and even primary prevention of embolic stroke.

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.

The search for a gold standard to clinically diagnose and monitor atrial cardiomyopathy

Tufano A, Lancellotti P. "Atrial cardiomyopathy: Pathophysiology and clinical implications". Eur J Intern Med. 2022 Mar 11:S0953-6205(22)00097-8. doi: 10.1016/j.ejim.2022.03.007. Epub ahead of print. PMID: 35288030.

Prevalence of markers of atrial cardiomyopathy in embolic stroke of undetermined source: A systematic review

BACKGROUND

Emerging evidence suggests the potential role of atrial cardiomyopathy (AC) as a direct thromboembolic determinant in embolic stroke of undetermined source (ESUS).

OBJECTIVE

We aimed to quantify the prevalence of potential AC markers among ESUS, non-cardioembolic (NCE) and cardioembolic (CE) stroke patients.

METHODS

PubMed and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched for publications from inception to October 2021, with duplicate data extraction and risk of bias assessment. The Newcastle-Ottawa assessment scale was used to evaluate study quality.

RESULTS

Among 398 screened studies, 11 observational studies with 2009 ESUS patients (mean age 66.5 years) fulfilled the inclusion criteria. Of electrocardiographic markers, increased P-wave terminal force in lead V1 was more prevalent in ESUS vs NCE (OR=2.26, 95%CI: 1.40-3.66). Of imaging markers, left atrial volume index (LAVI) and left atrial diameter (LAd) were higher in ESUS vs NCE (OR=1.04, 95%CI: 1.02-1.06 and OR=3.41, 95%CI: 1.35-8.61 respectively). Non-chicken wing morphology of the left atrial appendage was more frequent in ESUS compared to NCE patients in the majority of studies. Of serum biomarkers, the prevalence of NT-proBNP >250 pg/ml did not differ among ESUS vs NCE (OR=0.73, 95%CI: 0.39 -1.35).

CONCLUSIONS

Electrocardiographic, echocardiographic markers and advanced imaging modalities able to assess the morphologic characteristics of left atrial appendage and left atrial function may be important tools to discriminate AC among ESUS vs NCE stroke patients. Prospective studies exploring the association of potential AC markers with ESUS occurrence are warranted to validate their clinical utility.

Proteins and pathways in atrial fibrillation and atrial cardiomyopathy underlying cryptogenic stroke

Background

Atrial fibrillation (AF) is one of the most prevalent causes of cryptogenic stroke. Also, apart from AF itself, structural and remodelling changes in the atria might be an underlying cause of cryptogenic stroke. We aimed to discover circulating proteins and reveal pathways altered in AF and atrial cardiomyopathy, measured by left atrial volume index (LAVI) and peak atrial longitudinal strain (PALS), in patients with cryptogenic stroke.

Methods

An aptamer array (including 1310 proteins) was measured in the blood of 20 cryptogenic stroke patients monitored during 28 days with a Holter device as a case-control study of the Crypto-AF cohort. Protein levels were compared between patients with (n = 10) and without AF (n = 10) after stroke, and the best candidates were tested in 111 patients from the same cohort (44 patients with AF and 67 without AF). In addition, in the first 20 patients, proteins were explored according to PALS and LAVI values.

Results

Forty-six proteins were differentially expressed in AF cases. Of those, four proteins were tested in a larger sample size. Only DPP7, presenting lower levels in AF patients, was further validated. Fifty-seven proteins correlated with LAVI, and 270 correlated with PALS. NT-proBNP was common in all the discovery analyses performed. Interestingly, many proteins and pathways were altered in patients with low PALS.

Conclusions

Multiple proteins and pathways related to AF and atrial cardiomyopathy have been revealed. The role of DPP7 as a biomarker for stroke aetiology should be further explored. Moreover, the present study may be considered hypothesis-generating.

Atrial CARdiac Magnetic resonance imaging in patients with embolic stroke of unknown source without documented Atrial Fibrillation (CARM-AF): Study design and clinical protocol

Background

Initiation of anticoagulation therapy in ischemic stroke patients is contingent on a clinical diagnosis of atrial fibrillation (AF). Results from previous studies suggest thromboembolic risk may predate clinical manifestations of AF. Early identification of this cohort of patients may allow early initiation of anticoagulation and reduce the risk of secondary stroke.

Objective

This study aims to produce a substrate-based predictive model using cardiac magnetic resonance imaging (CMR) and baseline noninvasive electrocardiographic investigations to improve the identification of patients at risk of future thromboembolism.

Methods

CARM-AF is a prospective, multicenter, observational cohort study. Ninety-two patients will be recruited following an embolic stroke of unknown source (ESUS) and undergo atrial CMR followed by insertion of an implantable loop recorder (ILR) as per routine clinical care within 3 months of index stroke. Remote ILR follow-up will be used to allocate patients to a study or control group determined by the presence or absence of AF as defined by ILR monitoring.

Results

Baseline data collection, noninvasive electrocardiographic data analysis, and imaging postprocessing will be performed at the time of enrollment. Primary analysis will be performed following 12 months of continuous ILR monitoring, with interim and delayed analyses performed at 6 months and 2 and 3 years, respectively.

Conclusion

The CARM-AF Study will use atrial structural and electrocardiographic metrics to identify patients with AF, or at high risk of developing AF, who may benefit from early initiation of anticoagulation.

Comparison of various late gadolinium enhancement magnetic resonance imaging methods with high-definition voltage and activation mapping for detection of atrial cardiomyopathy

AIMS

Atrial cardiomyopathy (ACM) is associated with increased arrhythmia recurrence rates after pulmonary vein isolation (PVI). We compare the most common left atrial (LA) late gadolinium enhancement magnetic resonance imaging (LGE-MRI)-methods [Utah-method and image intensity ratio (IIR)-methods] and endocardial voltage mapping for ACM-detection and outcome prediction after PVI for atrial fibrillation (AF).

METHODS AND RESULTS

In this prospective observational study, 37 ablation-naive patients (66 ± 9 years, 84% male) with persistent AF underwent LA-LGE-MRI and high-definition voltage and activation mapping (2129 ± 484 sites) in sinus rhythm prior to PVI. The MRI-post-processing-analyses were performed by two independent expert laboratories. Arrhythmia recurrence was recorded within 12 months following PVI. The global ACM-extent was highly variable: median LA low-voltage substrate (LA-LVS) was 12.9% at <1.0 mV and 2.7% at <0.5 mV; median LA-LGE-extent using the Utah-method was 18.3% and 0.03-93.1% using the IIR-methods. The LA activation time was significantly correlated with LA-LVS (r = 0.76 at <0.5 mV and r = 0.82 at <1.0 mV, both P < 0.0001), but not with LA-LGE-extent. The highest regional matching between LA-LVS <0.5 mV and LA-LGE was found for the anterior wall in 57% of patients using the Utah-method and in 59% using IIR 1.20. The corresponding values for the posterior wall were 19% and 38%, respectively. Arrhythmia recurrence occurred in 15(41%) patients. Freedom from arrhythmia was significantly lower in those with LA-LVS ≥2 cm2 at 0.5 mV but not in those with LGE ≥20% (Utah-stages III and IV): 43% vs. 81%, P = 0.009 and 50% vs. 67%, P = 0.338, respectively.

CONCLUSION

Comparison of the most common LA-LGE-MRI methods and endocardial voltage mapping revealed large discrepancies in global and regional ACM-extent.

Left Atrial Remodeling and Cerebrovascular Disease Assessed by Magnetic Resonance Imaging in Continuously Monitored Patients

BACKGROUND

Atrial remodeling is associated with future atrial fibrillation (AF) and stroke. AF has been associated with cognitive impairment and cerebral white matter lesions. We wished to investigate the possible direct association between atrial remodeling and cerebrovascular disease in patients with and without AF documented by implantable loop recorder (ILR).

METHODS

Cardiac and cerebral magnetic resonance imaging were acquired in a cross-sectional study, including participants ≥70 years of age with stroke risk factors without known AF. Cerebrovascular disease was visually rated using the Fazekas scale and number of lacunar strokes. Left atrial (LA) and ventricular volumes and function were analyzed. Associations between atrial remodeling and cerebrovascular disease were assessed with logistic regression models. The analyses were stratified according to sinus rhythm or any AF during 3 months of continuous ILR monitoring to account for subclinical AF.

RESULTS

Of 200 participants investigated, 87% had a Fazekas score ≥1 and 45% had ≥1 lacunar infarct. Within 3 months of ILR monitoring, AF was detected in 28 (14%) participants. For participants with sinus rhythm (n = 172), lower LA passive emptying fraction was associated with Fazekas score after multivariable adjustment (OR [95% CI]: 0.51 [0.27; 0.86] p = 0.02), and increased LA maximum (OR [95% CI]: 1.38 [1.07; 1.82] p = 0.01) and minimum volumes (OR [95% CI]: 1.48 [1.03; 2.17] p = 0.04) were associated with lacunar infarcts. There were no significant associations in patients with AF.

CONCLUSION

In AF-free patients, as documented by ILR monitoring, we found an independent association between LA passive emptying fraction and Fazekas score and between atrial volumes and lacunar infarcts.

Non-invasive body surface electrocardiographic imaging for diagnosis of atrial cardiomyopathy

AIMS

Atrial cardiomyopathy (ACM) is associated with new-onset atrial fibrillation, arrhythmia recurrence after pulmonary vein isolation (PVI) and increased risk for stroke. At present, diagnosis of ACM is feasible by endocardial contact mapping of left atrial (LA) low-voltage substrate (LVS) or late gadolinium-enhanced magnetic resonance imaging, but their complexity limits a widespread use. The aim of this study was to assess non-invasive body surface electrocardiographic imaging (ECGI) as a novel clinical tool for diagnosis of ACM compared with endocardial mapping.

METHODS AND RESULTS

Thirty-nine consecutive patients (66 ± 9 years, 85% male) presenting for their first PVI for persistent atrial fibrillation underwent ECGI in sinus rhythm using a 252-electrode-array mapping system. Subsequently, high-density LA voltage and biatrial activation maps (mean 2090 ± 488 sites) were acquired in sinus rhythm prior to PVI. Freedom from arrhythmia recurrence was assessed within 12 months follow-up. Increased duration of total atrial conduction time (TACT) in ECGI was associated with both increased atrial activation time and extent of LA-LVS in endocardial contact mapping (r = 0.77 and r = 0.66, P < 0.0001 respectively). Atrial cardiomyopathy was found in 23 (59%) patients. A TACT value of 148 ms identified ACM with 91.3% sensitivity and 93.7% specificity. Arrhythmia recurrence occurred in 15 (38%) patients during a follow-up of 389 ± 55 days. Freedom from arrhythmia was significantly higher in patients with a TACT <148 ms compared with patients with a TACT ≥148 ms (82.4% vs. 45.5%, P = 0.019).

CONCLUSION

Analysis of TACT in non-invasive ECGI allows diagnosis of patients with ACM, which is associated with a significantly increased risk for arrhythmia recurrence following PVI.

Echocardiographic diagnosis of atrial cardiomyopathy allows outcome prediction following pulmonary vein isolation

BACKGROUND

Relevant atrial cardiomyopathy (ACM), defined as a left atrial (LA) low-voltage area ≥ 2 cm2 at 0.5 mV threshold on endocardial contact mapping, is associated with new-onset atrial fibrillation (AF), higher arrhythmia recurrence rates after pulmonary vein isolation (PVI), and an increased risk of stroke. The current study aimed to assess two non-invasive echocardiographic parameters, LA emptying fraction (EF) and LA longitudinal strain (LAS, during reservoir (LASr), conduit (LAScd) and contraction phase (LASct)) for the diagnosis of ACM and prediction of arrhythmia outcome after PVI.

METHODS

We prospectively enrolled 60 consecutive, ablation-naive patients (age 66 ± 9 years, 80% males) with persistent AF. In 30 patients (derivation cohort), LA-EF and LAS cut-off values for the presence of relevant ACM (high-density endocardial contact mapping in sinus rhythm prior to PVI at 3000 ± 1249 sites) were established in sinus rhythm and tested in a validation cohort (n = 30). Arrhythmia recurrence within 12 months was documented using 72-h Holter electrocardiograms.

RESULTS

An LA-EF of < 34% predicted ACM with an area under the curve (AUC) of 0.846 (sensitivity 69.2%, specificity 76.5%) similar to a LASr < 23.5% (AUC 0.878, sensitivity 92.3%, specificity 82.4%). In the validation cohort, these cut-offs established the correct diagnosis of ACM in 76% of patients (positive predictive values 87%/93% and negative predictive values 73%/75%, respectively). Arrhythmia recurrence in the entire cohort was significantly more frequent in patients with LA-EF < 34% and LASr < 23.5% (56% vs. 29% and 55% vs. 26%, both p < 0.05).

CONCLUSION

The echocardiographic parameters LA-EF and LAS allow accurate, non-invasive diagnosis of ACM and prediction of arrhythmia recurrence after PVI.

Rapid Risk Stratification of Acute Ischemic Stroke Patients in the Emergency Department: The Incremental Prognostic Role of Left Atrial Reservoir Strain

OBJECTIVES

To determine the prognostic value of positive global left atrial strain (LA-GSA+), measured by two-dimensional speckle tracking echocardiography (2D-STE) in a population of acute ischemic stroke (AIS) patients without atrial fibrillation (AF), in the setting of Emergency Department (ED).

METHODS

All consecutive AIS patients with sinus rhythm on ECG and without AF history entered this prospective study. All patients underwent complete blood tests and transthoracic echocardiography implemented with 2D-STE analysis of LA strain parameters within 6-12 h after symptoms onset. At 6-months follow-up, we evaluated the composite endpoint of all-cause mortality plus cardiovascular re-hospitalizations.

RESULTS

A total of 102 AIS patients (76.4 ± 10.8 yrs, 47% males) were prospectively included. LA-GSA+ was markedly reduced in AIS patients (20.8 ± 7.7%), without any statistically significant difference between the stroke subtypes. At 6-months follow-up, 7 deaths and 27 re-hospitalizations occurred. On multivariate Cox regression analysis, variables independently associated with outcome were: LA-GSA+ (per unit) (HR 0.29, 95% CI 0.19-0.39) and C-reactive protein (CRP) (per 0.1 mg/dl) (HR 1.45, 95% CI 1.15-1.75) as continuous variables; statin therapy (HR 0.45, 95%CI 0.28-0.62), and type 2 diabetes (HR 1.65, 95% CI 1.15-2.35) as categorical variables. A LA-GSA+ ≤20.0% predicted the occurrence of the above-mentioned outcome at 6-months follow-up with 94% sensitivity and 81% specificity (AUC=0.84). Interestingly, GSA+ showed a strong inverse correlation with CRP levels (r = -0.86).

CONCLUSIONS

A LA-GSA+ ≤20% reflects a more advanced atrial cardiomyopathy and might provide a rapid and reliable prognostic risk stratification of AIS patients without AF history in the setting of ED.

Determinants of exercise intolerance symptoms considered non-specific for heart failure in patients with stage A and B: role of the left atrium in the transition phase to overt heart failure

To assess to what extent left atrial (LA) structure and function are associated with non-specific heart failure symptoms, so that patients were classified as HF stage A and B. Mechanisms underlying the transition to overt HF in patients with stage A and B HF are unclear. Consecutive outpatients undergoing echocardiography and clinical evaluation and classified as HF stage A and B with preserved left ventricular ejection fraction (LVEF) were included. The association between LA measures [volume (LAVi), peak longitudinal-(PALS), contraction-(PACS) and conduit-strain] and non-specific HF symptoms was assessed using adjusted logistic regression analyses. The incremental value of atrial myopathy in symptoms prediction on top of clinical or echocardiographic confounders was assessed through ROC curves analyses. The cohort comprehended 185 patients (63 ± 16 years, 47% women) of whom 133 (72%) were asymptomatic, and 52 (28%) reported non-specific HF symptoms. After adjustment for clinical and echocardiographic confounders for HF symptoms, LAVi, PALS and PACS were associated with symptoms (p < 0.05). Among echocardiographic variables, only LA parameters were significantly associated with symptoms on top of clinical confounders (for LAVi OR [95% CI] 1.56 [1.21–2.00], p < 0.0001; for PALS 1.45 (1.10–1.91), p = 0.0009; for PACS 2.10 [1.33–3.30], p = 0.002). After adjustment for age, hypertension and COPD or E/E′, LV mass-i and mitral ERO, atrial myopathy added predictive value for symptoms presence compared to the clinical variables or echocardiographic parameters described (AUC increase 0.80 to 0.88, p = 0.004, and 0.79 to 0.84, p = 0.06, respectively). In patients with HF stages A–B and preserved LVEF, measures of LA structure and function were associated with non-specific HF symptoms. A comprehensive LA remodeling evaluation may help clinicians in the appropriate identification of overt HF.

Dynamic risk assessment to improve quality of care in patients with atrial fibrillation: the 7th AFNET/EHRA Consensus Conference

AIMS

The risk of developing atrial fibrillation (AF) and its complications continues to increase, despite good progress in preventing AF-related strokes.

METHODS AND RESULTS

This article summarizes the outcomes of the 7th Consensus Conference of the Atrial Fibrillation NETwork (AFNET) and the European Heart Rhythm Association (EHRA) held in Lisbon in March 2019. Sixty-five international AF specialists met to present new data and find consensus on pressing issues in AF prevention, management and future research to improve care for patients with AF and prevent AF-related complications. This article is the main outcome of an interactive, iterative discussion between breakout specialist groups and the meeting plenary. AF patients have dynamic risk profiles requiring repeated assessment and risk-based therapy stratification to optimize quality of care. Interrogation of deeply phenotyped datasets with outcomes will lead to a better understanding of the cardiac and systemic effects of AF, interacting with comorbidities and predisposing factors, enabling stratified therapy. New proposals include an algorithm for the acute management of patients with AF and heart failure, a call for a refined, data-driven assessment of stroke risk, suggestions for anticoagulation use in special populations, and a call for rhythm control therapy selection based on risk of AF recurrence.

CONCLUSION

The remaining morbidity and mortality in patients with AF needs better characterization. Likely drivers of the remaining AF-related problems are AF burden, potentially treatable by rhythm control therapy, and concomitant conditions, potentially treatable by treating these conditions. Identifying the drivers of AF-related complications holds promise for stratified therapy.

Effect of intensive blood pressure lowering on left atrial remodeling in the SPRINT

Upstream therapy of atrial remodeling may decrease atrial fibrillation and associated thromboembolism. We examined the impact of intensive BP lowering on ECG-defined left atrial abnormalities in the SPRINT. SPRINT was a randomized clinical trial comparing outcomes when a systolic BP of <120 mmHg (standard treatment) was the target. We included SPRINT participants without baseline atrial fibrillation who had a technically interpretable baseline ECG and at least one follow-up ECG. The primary outcome was incident left atrial abnormality, defined as P-wave terminal force in V₁ (PTFV₁) > 4000 μV × ms. Secondary outcomes were regression of the left atrial abnormality and the change in PTFV₁ from baseline across follow-up ECGs. Cox regression was used to examine the associations between treatment assignment and incident left atrial abnormality and its regression. We used linear mixed models to examine the changes in PTFV₁. Of 9361 SPRINT participants, 7738 qualified for this analysis, of whom 5544 did not have baseline left atrial abnormalities. Intensive BP management was not associated with incident left atrial abnormality (HR, 0.96; 95% CI, 0.87-1.07) or regression of the baseline left atrial abnormality (HR, 1.09; 95% CI, 0.98-1.21). The change in PTFV₁ from baseline through follow-up did not differ significantly between treatment groups (difference in μV × ms per year, 6; 95% CI, -67 to 79). Thus, among patients in a randomized clinical trial, we found no difference in the progression or regression of ECG-defined left atrial abnormalities with intensive BP management compared to standard BP management.

Abnormal P-wave terminal force in lead V1 is associated with low left atrial appendage ejection velocity

BACKGROUND

Sinus P-wave abnormalities have been associated stroke in people with atrial fibrillation (AF). The majority of AF-related strokes occur from left atrial appendage (LAA) thromboembolism. Dysfunction of the left atrium (LA) and left atrial appendage (LAA) can increase rates of thromboembolic stroke. We studied whether abnormal P wave terminal force in V1 (aPTFV1) is associated with decreased LAA ejection velocity (LAAV) on transesophageal echocardiography (TEE).

METHODS

We conducted a retrospective cross-sectional study reviewing patients at a tertiary care medical center who underwent TEE in sinus rhythm and had an interpretable sinus ECG within 12 months of TEE. Participants were excluded for complex congenital heart disease, age <18, cardiac transplantation, and chronic atrial pacing. Logistic regression analysis was used to estimate the odds ratios of LAAV<40 cm/s for aPTFV1.

RESULTS

In our final cohort of 169 patients (28% of which had LAAV <40), the multivariate odds ratio of aPTFV1 for LAAV<40 cm/s after adjustment for CHA₂DS₂VASc variables, heart rate during TEE, history of atrial arrhythmias, and left atrial volume index was 2.24 (95% CI of 1.13-6.00).

CONCLUSION

Abnromal P-wave terminal force in lead V1 is associated with low LAAV after adjustment for potential confounders. Future research is needed for validation of our findings and determination of clinical utility.

Abnormal P-wave terminal force in lead V1 is a marker for atrial electrical dysfunction but not structural remodelling

Aims

There is a lack of diagnostic and therapeutic options for patients with atrial cardiomyopathy and paroxysmal atrial fibrillation. Interestingly, an abnormal P‐wave terminal force in electrocardiogram lead V₁ (PTFV₁) has been associated with atrial cardiomyopathy, but this association is poorly understood. We investigated PTFV₁ as a marker for functional, electrical, and structural atrial remodelling.

Methods and results

Fifty‐six patients with acute myocardial infarction and 13 kidney donors as control cohort prospectively underwent cardiac magnetic resonance imaging to evaluate the association between PTFV₁ and functional remodelling (atrial strain). To further investigate underlying pathomechanisms, right atrial appendage biopsies were collected from 32 patients undergoing elective coronary artery bypass grafting. PTFV₁ was assessed as the product of negative P‐wave amplitude and duration in lead V₁ and defined as abnormal if ≥4000 ms*μV. Activity of cardiac Ca/calmodulin‐dependent protein kinase II (CaMKII) was determined by a specific HDAC4 pull‐down assay as a surrogate for electrical remodelling. Atrial fibrosis was quantified using Masson's trichrome staining as a measure for structural remodelling. Multivariate regression analyses were performed to account for potential confounders. A total of 16/56 (29%) of patients with acute myocardial infarction, 3/13 (23%) of kidney donors, and 15/32 (47%) of patients undergoing coronary artery bypass grafting showed an abnormal PTFV₁. In patients with acute myocardial infarction, left atrial (LA) strain was significantly reduced in the subgroup with an abnormal PTFV₁ (LA reservoir strain: 32.28 ± 12.86% vs. 22.75 ± 13.94%, P = 0.018; LA conduit strain: 18.87 ± 10.34% vs. 10.17 ± 8.26%, P = 0.004). Abnormal PTFV₁ showed a negative correlation with LA conduit strain independent from clinical covariates (coefficient B: −7.336, 95% confidence interval −13.577 to −1.095, P = 0.022). CaMKII activity was significantly increased from (normalized to CaMKII expression) 0.87 ± 0.17 to 1.46 ± 0.15 in patients with an abnormal PTFV₁ (P = 0.047). This increase in patients with an abnormal PTFV₁ was independent from clinical covariates (coefficient B: 0.542, 95% confidence interval 0.057 to 1.027, P = 0.031). Atrial fibrosis was significantly lower with 12.32 ± 1.63% in patients with an abnormal PTFV₁ (vs. 20.50 ± 2.09%, P = 0.006), suggesting PTFV₁ to be a marker for electrical but not structural remodelling.

Conclusions

Abnormal PTFV₁ is an independent predictor for impaired atrial function and for electrical but not for structural remodelling. PTFV₁ may be a promising tool to evaluate patients for atrial cardiomyopathy and for risk of atrial fibrillation.

Left atrial dimension and ischemic stroke in patients with and without atrial fibrillation

The incidence of ischemic stroke (IS) increases in patients with enlarged left atrium (LA) irrespective of whether or not the existence of atrial fibrillation (AF). In such situation, it is unclear whether the impact of LA on incidence of IS still significant in young, non-AF patients with enlarged LA who are primarily unconcerned on anticoagulation therapy. The study population consisted of 18,511 consecutive patients not receiving oral anticoagulants and undergoing echocardiography with measurement of LAD at baseline. The incidence rate of ischemic stroke was calculated in 3 groups according to left atrial dimension (LAD; < 30, 30-45 and ≥ 45 mm) in AF and non-AF patients. Further subgroup analysis was performed in stratification by elderly and young (aged ≥ 65 and < 65 years, respectively). The incidences of IS (per 100 patient-years) were 0.11 and 0.71 in non-AF and AF patients with LAD < 30 mm, respectively, which increased to 0.58 and 1.35 in LAD ≥ 45 mm (adjusted hazard ratios [HRs]; 1.95 [95% confidence intervals, CIs: 0.76-5.01] and 1.22 [95% CIs: 0.27-5.58], interaction P was 0.246). In non-AF patients, the incidences of IS were 0.30 and 0.04 in elderly and young patients with LAD < 30 mm, which increased to 0.67 and 0.48 in LAD ≥ 45 mm (adjusted HRs; 1.34 [95% CIs: 0.43-4.15] and 4.21 [95% CIs: 0.77-23.12], interaction P was 0.158). The incidence of IS significantly increased with increase of LAD in non-AF, especially in non-AF and young patients, although the difference was not independent of other clinical factors. The impact of LAD on IS was numerically larger in non-AF than in AF, and larger in young and non-AF than in elderly counterpart, although a significant interaction was not observed in this small population. Further studies with large population are necessary to judge whether these population with enlarged LA need antithrombotic therapy.

Cardiovascular magnetic resonance imaging and its role in the investigation of stroke: an update

Recent advances in complementary diagnostic exams have helped to clarify stroke etiology, not only by helping to confirm established stroke causes but also by unveiling new possible stroke mechanisms. Etiological investigation for cardioembolic stroke has benefited in the last years from information provided by studies analysing serum biomarkers, heart rhythm monitoring and imaging methods like cardiovascular magnetic resonance (CMR) imaging. CMR has been particularly important for the characterization of possible new cardioembolic stroke mechanisms including atrial cardiomyopathy, silent myocardial infarction and cardiomyopathies.

Dual SGLT-1 and SGLT-2 inhibition improves left atrial dysfunction in HFpEF

BACKGROUND

Sodium-glucose linked transporter type 2 (SGLT-2) inhibition has been shown to reduce cardiovascular mortality in heart failure independently of glycemic control and prevents the onset of atrial arrhythmias, a common co-morbidity in heart failure with preserved ejection fraction (HFpEF). The mechanism behind these effects is not fully understood, and it remains unclear if they could be further enhanced by additional SGLT-1 inhibition. We investigated the effects of chronic treatment with the dual SGLT-1&2 inhibitor sotagliflozin on left atrial (LA) remodeling and cellular arrhythmogenesis (i.e. atrial cardiomyopathy) in a metabolic syndrome-related rat model of HFpEF.

METHODS

17 week-old ZSF-1 obese rats, a metabolic syndrome-related model of HFpEF, and wild type rats (Wistar Kyoto), were fed 30 mg/kg/d sotagliflozin for 6 weeks. At 23 weeks, LA were imaged in-vivo by echocardiography. In-vitro, Ca2+ transients (CaT; electrically stimulated, caffeine-induced) and spontaneous Ca2+ release were recorded by ratiometric microscopy using Ca2+-sensitive fluorescent dyes (Fura-2) during various experimental protocols. Mitochondrial structure (dye: Mitotracker), Ca2+ buffer capacity (dye: Rhod-2), mitochondrial depolarization (dye: TMRE) and production of reactive oxygen species (dye: H2DCF) were visualized by confocal microscopy. Statistical analysis was performed with 2-way analysis of variance followed by post-hoc Bonferroni and student's t-test, as applicable.

RESULTS

Sotagliflozin ameliorated LA enlargement in HFpEF in-vivo. In-vitro, LA cardiomyocytes in HFpEF showed an increased incidence and amplitude of arrhythmic spontaneous Ca2+ release events (SCaEs). Sotagliflozin significantly reduced the magnitude of SCaEs, while their frequency was unaffected. Sotagliflozin lowered diastolic [Ca2+] of CaT at baseline and in response to glucose influx, possibly related to a ~ 50% increase of sodium sodium-calcium exchanger (NCX) forward-mode activity. Sotagliflozin prevented mitochondrial swelling and enhanced mitochondrial Ca2+ buffer capacity in HFpEF. Sotagliflozin improved mitochondrial fission and reactive oxygen species (ROS) production during glucose starvation and averted Ca2+ accumulation upon glycolytic inhibition.

CONCLUSION

The SGLT-1&2 inhibitor sotagliflozin ameliorated LA remodeling in metabolic HFpEF. It also improved distinct features of Ca2+-mediated cellular arrhythmogenesis in-vitro (i.e. magnitude of SCaEs, mitochondrial Ca2+ buffer capacity, diastolic Ca2+ accumulation, NCX activity). The safety and efficacy of combined SGLT-1&2 inhibition for the treatment and/or prevention of atrial cardiomyopathy associated arrhythmias should be further evaluated in clinical trials.

Cellular and mitochondrial mechanisms of atrial fibrillation

The molecular mechanisms underlying atrial fibrillation (AF), the most common form of arrhythmia, are poorly understood and therefore target-specific treatment options remain an unmet clinical need. Excitation–contraction coupling in cardiac myocytes requires high amounts of adenosine triphosphate (ATP), which is replenished by oxidative phosphorylation in mitochondria. Calcium (Ca²⁺) is a key regulator of mitochondrial function by stimulating the Krebs cycle, which produces nicotinamide adenine dinucleotide for ATP production at the electron transport chain and nicotinamide adenine dinucleotide phosphate for the elimination of reactive oxygen species (ROS). While it is now well established that mitochondrial dysfunction plays an important role in the pathophysiology of heart failure, this has been less investigated in atrial myocytes in AF. Considering the high prevalence of AF, investigating the role of mitochondria in this disease may guide the path towards new therapeutic targets. In this review, we discuss the importance of mitochondrial Ca²⁺ handling in regulating ATP production and mitochondrial ROS emission and how alterations, particularly in these aspects of mitochondrial activity, may play a role in AF. In addition to describing research advances, we highlight areas in which further studies are required to elucidate the role of mitochondria in AF.

Atrial fibrillation: villain or bystander in vascular brain injury

Atrial fibrillation (AF) and stroke are inextricably connected, with classical Virchow pathophysiology explaining thromboembolism through blood stasis in the fibrillating left atrium. This conceptualization has been reinforced by the remarkable efficacy of oral anticoagulant (OAC) for stroke prevention in AF. A number of observations showing that the presence of AF is neither necessary nor sufficient for stroke, cast doubt on the causal role of AF as a villain in vascular brain injury (VBI). The requirement for additional risk factors before AF increases stroke risk; temporal disconnect of AF from a stroke in patients with no AF for months before stroke during continuous ECG monitoring but manifesting AF only after stroke; and increasing recognition of the role of atrial cardiomyopathy and atrial substrate in AF-related stroke, and also stroke without AF, have led to rethinking the pathogenetic model of cardioembolic stroke. This is quite separate from recognition that in AF, shared cardiovascular risk factors can lead both to non-embolic stroke, or emboli from the aorta and carotid arteries. Meanwhile, VBI is now expanded to include dementia and cognitive decline: research is required to see if reduced by OAC. A changed conceptual model with less focus on the arrhythmia, and more on atrial substrate/cardiomyopathy causing VBI both in the presence or absence of AF, is required to allow us to better prevent AF-related VBI. It could direct focus towards prevention of the atrial cardiomyopathy though much work is required to better define this entity before the balance between AF as villain or bystander can be determined.

The role of postprandial very-low-density lipoprotein in the development of atrial remodeling in metabolic syndrome

Background

Negatively charged very-low-density lipoprotein (VLDL-χ) in metabolic syndrome (MetS) patients exerts cytotoxic effects on endothelial cells and atrial myocytes. Atrial cardiomyopathy, manifested by atrial remodeling with a dilated diameter, contributes to atrial fibrillation pathogenesis and predicts atrial fibrillation development. The correlation of VLDL-χ with atrial remodeling is unknown. This study investigated the association between VLDL-χ and remodeling of left atrium.

Methods

Consecutively, 87 MetS and 80 non-MetS individuals between 23 and 74 years old (50.6% men) without overt cardiovascular diseases were included in the prospective cohort study. Blood samples were collected while fasting and postprandially (at 0.5, 1, 2, and 4 h after a unified meal). VLDL was isolated by ultracentrifugation; the percentile concentration of VLDL-χ (%) was determined by ultra-performance liquid chromatography. The correlations of left atrium diameter (LAD) with variables including VLDL-χ, LDL-C, HDL-C, triglycerides, glucose, and blood pressure, were analyzed by multiple linear regression models. A hierarchical linear model was conducted to test the independencies of each variable’s correlation with LAD.

Results

The mean LAD was 3.4 ± 0.5 cm in non-MetS subjects and 3.9 ± 0.5 cm in MetS patients (P < 0.01). None of the fasting lipid profiles were associated with LAD. VLDL-χ, BMI, waist circumference, hip circumference, and blood pressure were positively correlated with LAD (all P < 0.05) after adjustment for age and sex. Significant interactions between VLDL-χ and blood pressure, waist circumference, and hip circumference were observed. When adjusted for obesity- and blood pressure-related variables, 2-h postprandial VLDL-χ (mean 1.30 ± 0.61%) showed a positive correlation with LAD in MetS patients. Each 1% VLDL-χ increase was estimated to increase LAD by 0.23 cm.

Conclusions

Postprandial VLDL-χ is associated with atrial remodeling particularly in the MetS group. VLDL-χ is a novel biomarker and may be a therapeutic target for atrial cardiomyopathy in MetS patients.

Trial registration

ISRCTN 69295295. Retrospectively registered 9 June 2020.

Beyond CHA2DS2-VASc in atrial fibrillation: the atrium and the risk of stroke

Pathology affecting the atria have a significant impact on the occurrence of arrhythmias and the risk of stroke. The causal relationship between atrial fibrillation (AF) and ischaemic stroke has been challenged by the recent uncovering of the lack of temporal association between thrombo-embolic cerebral events and paroxysmal AF or tachycardia. General conditions, such as the one considered in the definition of the CHA₂DS₂-VASc score, or specific atrial pathology (also independently occurring), could predispose to cerebral embolism.