Identification and electrophysiological characterization of early left atrial structural remodeling as a predictor for atrial fibrillation recurrence after pulmonary vein isolation

Quantification of atrial cardiomyopathy disease severity by electroanatomic voltage mapping and cardiac magnetic resonance imaging

INTRODUCTION

Atrial late gadolinium enhancement (Atrial-LGE) and electroanatomic voltage mapping (Atrial-EAVM) quantify the anatomical and functional extent of atrial cardiomyopathy. We aimed to explore the relationships between, and outcomes from, these modalities in patients with atrial fibrillation undergoing ablation.

METHODS

Patients undergoing first-time ablation had disease severities quantified using both Atrial-LGE and Atrial-EAVM. Correlations between modalities and their relationships with clinical features and arrhythmia recurrence were assessed.

RESULTS

In 123 atrial fibrillation patients (60 ± 10 years), Atrial-EAVM was moderately correlated with Atrial-LGE (r = .34, p < .001), with a mean fibrosis burden of 47.2% ± 14.91%. Agreement was strongest in the highest tertile of fibrosis burden (mean of differences 16.8% (95% CI = -24.4% to 57.9%, p = .433). Fibrosis burden was greater for Atrial-LGE than Atrial-EAVM (50.7% ± 10.7% vs. 13.7% ± 7.13%, p < .005) for patients in the lowest tertile who were younger, had smaller atria and a greater frequency of paroxysmal atrial fibrillation. Both Atrial EAVM and Atrial LGE were associated with recurrence of arrhythmia following ablation (Atrial-LGE HR = 1.02 (95% CI = 1.01-1.04), p = .047; Atrial-EAVM HR = 1.02 (95% CI = 1.005-1.03), p = .007). A low fibrosis burden (<15%) by Atrial-EAVM identified patients with very low arrhythmia recurrence. In contrast, a much higher fibrosis burden (>66%) by Atrial-LGE identified patients failing to respond to ablation.

CONCLUSIONS

We demonstrate for the first time that the level of agreement between Atrial-EAVM and Atrial-LGE is dependent on the level of atrial cardiomyopathy disease severity. The functional consequences of atrial cardiomyopathy are most evident in patients with the highest anatomical extent of disease.

High-density mapping in catheter ablation for atrial fibrillation in Asia Pacific region: An observational study

Background

Few clinical studies of atrial fibrillation (AF) have focused on Asian patients; data are lacking on current mapping and ablation strategies in the Asia Pacific region (APAC).

Objective

The HD Mapping Observational Study (NCT04022954) was designed to characterize electroanatomic mapping (EAM) with market-released high-density mapping (HDM) catheters in subjects with AF in APAC.

Methods

Subjects undergoing HDM and indicated for radiofrequency ablation (RFA) to treat AF were prospectively enrolled in APAC. Data included mapping strategy and ablation targets. EAM was performed using one of two commercially available HDM catheters (Advisor™ HD Grid, Sensor Enabled™, Abbott [GRID] or Inquiry™ AFocus II™ Double Loop, Abbott [DL]). Procedure-related adverse events were collected.

Results

Two hundred subjects were enrolled at 15 centers: 164 with symptomatic paroxysmal (PAF) and 36 with symptomatic persistent (PersAF) AF for de novo ablation. GRID and DL were used in 186 and 14 cases, respectively. All subjects underwent voltage mapping, with conservative thresholds (low voltage ≤0.5 mV and very low voltage/electrical scar ≤0.1 mV) used in 60.2% and 35.4% of maps, respectively. Focal impulses, rotors, complex fractionated electrograms, and other substrate targets were each searched for in <3% of subjects. Median time to generate a map was 9.0 (Q1: 5.0, Q3: 13.0) minutes. Ablation strategy included pulmonary vein (PV) isolation in all, and non-PV triggers in 75/200 (37.5%) subjects. Five serious adverse events were reported.

Conclusions

The study demonstrated an efficient strategy with the feasibility and safety of using HDM during AF ablation procedures in APAC.

Contact-force local impedance algorithm to guide effective pulmonary vein isolation in AF patients: 1-year outcome from an international multicenter clinical setting

BACKGROUND

The combination of highly localized impedance (LI) and contact force (CF) may improve tissue characterization and lesion prediction during radiofrequency (RF) pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF).

OBJECTIVE

We report the outcomes of our acute and long-term clinical evaluation of CF-LI-guided PVI in consecutive AF ablation cases from an international multicenter clinical setting.

METHODS

Three hundred twenty-four consecutive patients from 20 European centers undergoing RF catheter ablation with the Stablepoint™ catheter were enrolled in the CHARISMA registry. Of these, 275 had a minimum follow-up of 1 year and were included in the primary analysis.

RESULTS

The mean procedure duration was 115 ± 47 min, and the mean fluoroscopy time was 9.9 ± 6 min. At the end of the procedures, all PVs had been successfully isolated in all study patients. Minor complications were reported in 12 patients (4.4%). At 1 year, 36 (13.1%) patients had had an AF recurrence, and freedom from antiarrhythmic drugs and AF recurrence was achieved in 228 (82.9%) patients. The recurrence rate was higher in patients with persistent AF (21/116, 18.1%) than in those with paroxysmal AF (15/159, 9.4%; p = 0.0459). On multivariate logistic analysis adjusted for baseline confounders, only time > 6 months from first diagnosis of AF to ablation (HR = 2.93, 95%CI 1.03 to 8.36, p = 0.0459) was independently associated with recurrences.

CONCLUSION

An ablation strategy for PVI guided by CF-LI technology proved safe and effective and resulted in a low recurrence rate of AF over 1-year follow-up, irrespective of the underlying AF type.

CLINICAL TRIAL REGISTRATION

Catheter Ablation of Arrhythmias with a High-Density Mapping System in Real-World Practice. (CHARISMA). URL: http://clinicaltrials.gov/ Identifier: NCT03793998.

Clinical relevance of left atrial structural remodeling and non-pulmonary vein foci in atrial fibrillation

BACKGROUND

The mechanistic role of left atrial (LA) structural remodeling as a non-pulmonary vein (PV) trigger in the initiation of atrial fibrillation (AF) remains uncertain. This study is aimed at prospectively evaluating the association between non-PV triggers and LA structural remodeling.

METHODS

A total of 517 patients undergoing catheter ablation for AF were included. After PV isolation, a standardized protocol was implemented to reveal non-PV triggers, which included burst pacing into AF followed by cardioversion during isoproterenol infusion. If pacing-induced atrial tachycardia (AT) was observed, mapping and catheter ablation were performed.

RESULTS

The mean percentage of LA low-voltage area (LVA) < 0.5 mV incrementally increased during right atrial pacing among the no induction (n = 470), AF (n = 21), and AT (n = 26) groups (2.6 ± 5.7%, 5.5 ± 6.4%, and 18.0 ± 21.5%, respectively; P < 0.001). In the AF induction group, non-PV foci originated from the left atrium in 13 of 25 foci (52%), and 8 of 13 LA non-PV foci (62%) were located in the septal region. All except 1 focus originated from the non-LVA < 0.5 mV (8%), but 8 of the 13 LA foci originated from the LVA < 1.0 mV (62%). There were no differences in AF recurrence among the groups (log-rank, P = 0.160).

CONCLUSION

The majority of non-PV foci in the LA originated outside regions with advanced structural remodeling, thus suggesting the limited effectiveness of adjunctive ablation guided by the LVA < 0.5 mV during sinus rhythm in eliminating non-PV triggers.

Symptoms of gastroesophageal reflux disease predicts low voltage zones in the posteroinferior left atrium in patients with persistent atrial fibrillation

Background

The presence of low voltage zones (LVZs) in the left atrium (LA) is associated with the recurrence of atrial fibrillation (AF) after pulmonary vein isolation. Numerous studies have posited a link between gastroesophageal reflux disease (GERD) and AF, attributing this relationship to the anatomical proximity of the esophagus to the posteroinferior wall of the LA.

Objective

The objective of this study was to investigate whether GERD can predict the presence of LVZs in the posteroinferior wall of the LA.

Methods

Five hundred fifty-one patients with persistent AF, scheduled for their first AF ablation procedure, were prospectively enrolled. Voltage maps were collected using a multipolar catheter, and LVZs were defined as areas measuring ≥3 cm2 with a peak-to-peak bipolar voltage of <0.5 mV. Information on GERD symptoms was collected from the participants through a self-administered questionnaire.

Results

Long-standing persistent AF was present in 22.3% of the total cohort. GERD was present in 29% of patients and LVZs in the posteroinferior wall in 12.7%. In the multivariable analysis, patients with GERD were found to have more than twice the odds (odds ratio 2.26; 95% confidence interval 1.24-4.13; P = .008) of exhibiting LVZs in the posteroinferior wall of the LA than patients without GERD. GERD was not associated with LVZs in any other region of the LA.

Conclusion

GERD was found to be independently associated with LVZs in the posteroinferior LA. This association may be attributable to inflammation and may partly explain the link between GERD and AF.

Predictors of low-voltage zones in patients with persistent atrial fibrillation eligible for catheter ablation: An observational study

INTRODUCTION

The presence of low-voltage zones (LVZs) in the left atrium (LA) is associated with the recurrence of atrial fibrillation (AF) following pulmonary vein isolation (PVI). However, there is variability and conflict in the data regarding predictors of LVZs as reported in previous studies. The objective of this study was to identify predictors for the presence of LVZs in a cohort of patients with persistent AF.

METHODS

The study prospectively enrolled 439 patients with persistent AF who were scheduled for ablation. Voltage map of the LA was collected using a multipolar catheter. An LVZ was defined as an area of ≥3 cm2 exhibiting a peak-to-peak bipolar voltage of <0.5 mV.

RESULTS

The mean age of the cohort was 65.3 ± 8.6 years and 26.4% were female. Additionally, 25.7% had significant LVZs, most frequently located in the anterior wall of the LA. Multivariable analysis identified the following independent predictors for LVZ: advanced age (OR [odds ratio] = 1.08, 95% CI [confidence interval] = 1.03-1.13, p = .002); female sex (OR = 4.83, 95% CI = 2.66-8.76, p < .001); coronary artery disease (CAD) (OR = 3.20, 95% CI = 1.32-7.77, p = .01) and enlarged LA diameter (OR = 1.10, 95% CI = 1.04-1.17, p = .001). The area under the curve (AUC) of the receiver operating characteristic (ROC) curve for the final model was 0.829.

CONCLUSION

Approximately 25% of the patients with persistent AF had LVZs. Advanced age, female sex, CAD, and a larger LA were independent predictors for LVZs with the model demonstrating a very good AUC for the ROC curve. These findings hold the potential to be used to tailor the ablation procedure for the individual patient.

Comparison of voltages between atria: differences in sinus rhythm and atrial fibrillation

BACKGROUND

Ultra high-density mapping systems allow for comparison of atrial electroanatomical maps in unprecedented detail. Atrial scar determined by voltages and surface area between atria, rhythm and atrial fibrillation (AF) types was assessed.

METHODS

Left (LA) and right atrial (RA) maps were created using Rhythmia HDx in patients listed for ablation for paroxysmal (PAF, sinus rhythm (SR) maps only) or persistent AF (PeAF, AF and SR maps). Electrograms on corresponding SR/AF maps were paired for direct comparison. Percentage surface area of scar was assigned low- (LVM, ≤ 0.05 mV), intermediate- (IVM, 0.05-0.5 mV) or normal voltage myocardium, (NVM, > 0.5 mV).

RESULTS

Thirty-eight patients were recruited generating 96 maps using 913,480 electrograms. Paired SR-AF bipolar electrograms showed fair correlation in LA (Spearman's ρ = 0.32) and weak correlation in RA (ρ = 0.19) and were significantly higher in SR in both (LA: 0.61 mV (0.20-1.67) vs 0.31 mV (0.10-0.74), RA: 0.68 mV (0.19-1.88) vs 0.47 mV (0.14-1.07), p < 0.0005 both). Voltages were significantly higher in patients with PAF over PeAF, (LA: 1.13 mV (0.39-2.93) vs 0.52 mV (0.16-1.49); RA: 0.93 mV (0.24-2.46) vs 0.57 mV (0.17-1.69)). Minimal differences were seen in electrogram voltages between atria. Significantly more IVM/LVM surface areas were seen in AF over SR (LA only, p < 0005), and PeAF over PAF (LA: p = 0.01, RA: p = 0.04). There was minimal difference between atria within patients.

CONCLUSIONS

Ultra high-density mapping shows paired electrograms correlate poorly between SR and AF. SR electrograms are typically (but not always) larger than those in AF. Patients with PeAF have a lower global electrogram voltage than those with PAF. Electrogram voltages are similar between atria within individual patients.

Baseline left atrial low-voltage area predicts recurrence after pulmonary vein isolation: WAVE-MAP AF results

AIMS

Electro-anatomical mapping may be critical to identify atrial fibrillation (AF) subjects who require substrate modification beyond pulmonary vein isolation (PVI). The objective was to determine correlations between pre-ablation mapping characteristics and 12-month outcomes after a single PVI-only catheter ablation of AF.

METHODS AND RESULTS

This study enrolled paroxysmal AF (PAF), early persistent AF (PsAF; 7 days-3 months), and non-early PsAF (>3-12 months) subjects undergoing de novo PVI-only radiofrequency catheter ablation. Sinus rhythm (SR) and AF voltage maps were created with the Advisor HD Grid™ Mapping Catheter, Sensor Enabled™ for each subject, and the presence of low-voltage area (LVA) (low-voltage cutoffs: 0.1-1.5 mV) was investigated. Follow-up visits were at 3, 6, and 12 months, with a 24-h Holter monitor at 12 months. A Cox proportional hazards model identified associations between mapping data and 12-month recurrence after a single PVI procedure. The study enrolled 300 subjects (113 PAF, 86 early PsAF, and 101 non-early PsAF) at 18 centres. At 12 months, 75.5% of subjects were free from AF/atrial flutter (AFL)/atrial tachycardia (AT) recurrence. Univariate analysis found that arrhythmia recurrence did not correlate with AF diagnosis, but LVA was significantly correlated. Low-voltage area (<0.5 mV) >28% of the left atrium in SR [hazard ratio (HR): 4.82, 95% confidence interval (CI): 2.08-11.18; P = 0.0003] and >72% in AF (HR: 5.66, 95% CI: 2.34-13.69; P = 0.0001) was associated with a higher risk of AF/AFL/AT recurrence at 12 months.

CONCLUSION

Larger extension of LVA was associated with an increased risk of arrhythmia recurrence. These subjects may benefit from substrate modification beyond PVI.

High-resolution mapping of reentrant atrial tachycardias: Relevance of low bipolar voltage

BACKGROUND

Bipolar voltage is widely used to characterize the atrial substrate but has been poorly validated, particularly during clinical tachycardias.

OBJECTIVE

The purpose of this study was to evaluate the diagnostic performance of voltage thresholds for identifying regions of slow conduction during reentrant atrial tachycardias (ATs).

METHODS

Thirty bipolar voltage and activation maps created during reentrant ATs were analyzed to (1) examine the relationship between voltage amplitude and conduction velocity (CV), (2) measure the diagnostic ability of voltage thresholds to predict CV, and (3) identify determinants of AT circuit dimensions. Voltage amplitude was categorized as "normal" (>0.50 mV), "abnormal" (0.05-0.50 mV), or "scar" (<0.05 mV); slow conduction was defined as <30 cm/s.

RESULTS

A total of 266,457 corresponding voltage and CV data points were included for analysis. Voltage and CV were moderately correlated (r = 0.407; P < .001). Bipolar voltage predicted regions of slow conduction with an area under the receiver operating characteristic curve of 0.733 (95% confidence interval 0.731-0.735). A threshold of 0.50 mV had 91% sensitivity and 35% specificity for identifying slow conduction, whereas 0.05 mV had 36% sensitivity and 87% specificity, with an optimal voltage threshold of 0.15 mV. Analyses restricted to the AT circuits identified weaker associations between voltage and CV and an optimal voltage threshold of 0.25 mV.

CONCLUSION

Widely used bipolar voltage amplitude thresholds to define "abnormal" and "scar" tissue in the atria are, respectively, sensitive and specific for identifying regions of slow conduction during reentrant ATs. However, overall, the association of voltage with CV is modest. No clinical predictors of AT circuit dimensions were identified.

The utility of combining continuous wavelet transform analysis and high-density voltage map in predicting the long-term outcomes after ablation of persistent atrial fibrillation

BACKGROUND

Continuous wavelet transform (CWT) analysis is a frequency analysis to detect areas of stable high-frequent activity (stable pseudo frequency [sPF]) during atrial fibrillation (AF). As previously reported, patients with the highest sPF area in pulmonary veins (PV) showed better short-term outcomes after PV isolation (PVI). This study sought to evaluate the efficacy of CWT analysis in predicting the long-term (2 years) outcomes after PVI. We also combined the left atrial (LA) voltage map with CWT analysis to further predict the outcome.

METHODS

Persistent AF patients (n = 109, age 65 ± 10) underwent a CWT analysis at PVs and 8 LA sites during AF for pre-PVI analysis. After PVI during AF, CWT analysis was performed again in the LA as post-PVI analysis and was compared with pre-PVI analysis. A sinus voltage map of LA was created after cardioversion.

RESULTS

Seventy patients had the highest sPF within PVs (PV-dominant group), while 39 patients had the highest sPF outside PVs (LA-dominant group). The global frequency in the LA showed a significant decrease after PVI only in PV-dominant group (6.55 ± 0.27 to 6.43 ± 0.37, P < 0.01). AF-free survival was better in PV-dominant group than LA-dominant group at 2-year follow-up (87.1% vs. 64.3%, P < 0.002). This trend was recognized throughout all degrees of low voltage area in the LA (LA-LVA), and AF-free survival was well predicted by combining CWT analysis and LA-LVA.

CONCLUSIONS

By combining CWT analysis and sinus LA-LVA, the long-term AF-free survival after PVI was well stratified and predicted.

Characterization of Atrial Substrate to Predict the Success of Pulmonary Vein Isolation: The Prospective, Multicenter MASH-AF II (Multipolar Atrial Substrate High Density Mapping in Atrial Fibrillation) Study

Background Left atrial substrate may have mechanistic relevance for ablation of atrial fibrillation (AF). We sought to analyze the relationship between low-voltage zones (LVZs), transition zones, and AF recurrence in patients undergoing pulmonary vein isolation. Methods and Results We conducted a prospective multicenter study on consecutive patients undergoing pulmonary vein isolation-only approach. LVZs and transition zones (0.5-1 mV) were analyzed offline on high-density electroanatomical maps collected before pulmonary vein isolation. Overall, 262 patients (61±11 years, 31% female) with paroxysmal (130 pts) or persistent (132 pts) AF were included. After 28 months of follow-up, 73 (28%) patients experienced recurrence. An extension of more than 5% LVZ in paroxysmal AF and more than 15% in persistent AF was associated with recurrence (hazard ratio [HR], 4.4 [95% CI, 2.0-9.8], P<0.001 and HR, 1.9 [95% CI, 1.1-3.7], P=0.04, respectively). Significant association was found between LVZs and transition zones and between LVZs and left atrial volume index (LAVI) (both P<0.001). Thirty percent of patients had significantly increased LAVI without LVZs. Eight percent of patients had LVZs despite normal LAVI. Older age, female sex, oncological history, and increased AF recurrence characterized the latter subgroup. Conclusions In patients undergoing first pulmonary vein isolation, the impact of LVZs on outcomes occurs with lower burden in paroxysmal than persistent AF, suggesting that not all LVZs have equal prognostic implications. A proportional area of moderately decreased voltages accompanies LVZs, suggesting a continuous substrate instead of the dichotomous division of healthy or diseased tissue. LAVI generally correlates with LVZs, but a small subgroup of patients may present with disproportionate atrial remodeling, despite normal LAVI.

Low voltage-guided ablation of posterior wall improves 5-year arrhythmia-free survival in persistent atrial fibrillation

INTRODUCTION

The posterior wall (PW) has been proposed as a standard target for ablation beyond pulmonary vein antral isolation (PVI) in patients with persistent atrial fibrillation (AF). However, studies have shown inconsistent outcomes with the addition of PW ablation. The presence or absence of low voltage on the PW may explain these inconsistencies. We evaluated whether PW ablation based on the presence or absence of low voltage improves long-term arrhythmia-free outcomes.

METHODS

We retrospectively reviewed 5-year follow-up in 152 consecutive patients who received either standard ablation (SA) with PVI alone or PVI + PW ablation (PWA) based on physician discretion (n = 77) or voltage-guided ablation (VGA) with PVI and addition of PWA only if low voltage was present on the PW (n = 75).

RESULTS

The two groups were well matched for baseline characteristics. At 5-year follow-up, 64% of patients receiving VGA were atrial tachyarrhythmia (AT)/AF free compared to 34% receiving SA (HR 0.358 p < .005). PWA had similar AF recurrence in SA and VGA groups (0.30 vs. 0.27 p = .96) but higher AT recurrence when comparing SA and VGA groups (0.39 vs. 0.15 p = .03). In multivariate analysis, both VGA and PWA predicted AF arrhythmia-free survival (HR 0.33, p = .001 and HR 0.20, p = .008, respectively). For AT, VGA predicted arrhythmia-free survival (HR 0.22, p = .028), while PWA predicted AT recurrence (HR 4.704, p = .0219).

CONCLUSION

VGA of the posterior wall ablation beyond PVI in persistent AF significantly improves long-term arrhythmia-free survival when compared with non-voltage-guided ablation. PW ablation without voltage-guidance reduced AF recurrence but at the cost of a higher incidence of AT.

A systematic review and meta-analysis of the safety and efficacy of left atrial substrate modification in atrial fibrillation patients with low voltage areas

Background

The left atrial low-voltage areas (LVAs) are associated with atrial fibrosis; however, it is not clear how the left atrial LVAs affect the recurrence of arrhythmias after catheter ablation, and the efficacy and safety of the left atrial substrate modification based on LVAs as a strategy for catheter ablation of atrial fibrillation (AF) are not evident for AF patients with LVAs.

Methods

We performed a systematic search to compare the arrhythmia recurrence in AF patients with and without LVAs after conventional ablation and arrhythmia recurrence in LVAs patients after conventional ablation with and without substrate modification based on LVAs.

Result

A total of 6 studies were included, involving 1,175 patients. The arrhythmia recurrence was higher in LVA patients after conventional ablation (OR: 5.14, 95% CI: [3.11, 8.49]; P < 0.00001). Additional LVAs substrate modification could improve the freedom of arrhythmia in LVAs patients after the first procedure (OR: 0.30, 95% CI: [0.15, 0.62]; P = 0.0009). However, there was no significant difference after multiple procedures (P = 0.19). The procedure time (MD: 26.61, 95% CI [15.79, 37.42]; P < 0.00001) and fluoroscopy time (MD: 6.90, 95% CI [4.34, 9.47]; P < 0.00001) in LVAs patients with additional LVAs substrate modification were significantly increased compared to LVAs patients' without substrate modification. Nevertheless, there were no higher LVAs substrate modification-related complications (P = 0.93) between LVAs patients with and without additional LVAs substrate modification. In the subgroup analysis, the additional LVAs substrate modification reduced the risk of arrhythmia recurrence in LVAs patients during the follow-up time, which was 12 months (OR: 0.32, 95% CI (0.17, 0.58); P = 0.002), and box isolation (OR: 0.37, 95% CI (0.20, 0.69); P = 0.002) subgroups, but the type of AF, follow up >12 months and homogenization subgroups were not statistically significant. Trial sequential analysis shows conclusive evidence for the LVAs ablation.

Conclusion

This study has shown that LVAs could improve the risk of arrhythmia recurrence in AF patients after conventional ablation. And additional LVAs substrate modification after conventional ablation could increase the freedom of arrhythmia recurrence in LVAs patients. Interestingly, the box isolation approach appeared more promising.

Systematic review registration

[http://www.crd.york.ac.uk/prospero], identifier [CRD42021239277].

Echocardiographic and Electrocardiographic Determinants of Atrial Cardiomyopathy Identify Patients with Atrial Fibrillation at Risk for Left Atrial Thrombogenesis

Objective: Atrial cardiomyopathy (ACM) is associated with development of AF, left atrial (LA) thrombogenesis, and stroke. Diagnosis of ACM is feasible using both echocardiographic LA strain imaging and measurement of the amplified p-wave duration (APWD) in digital 12-lead-ECG. We sought to determine the thresholds of LA global longitudinal strain (LA-GLS) and APWD that identify patients with AF at risk for LA appendage (LAA) thrombogenesis. Methods: One hundred and twenty-eight patients with a history of AF were included. Left atrial appendage maximal flow velocity (LAA-Vel, in TEE), LA-GLS (TTE), and APWD (digital 12-lead-ECG) were measured in all patients. ROC analysis was performed for each method to determine the thresholds for LA-GLS and the APWD, enabling diagnosis of patients with LAA-thrombus. Results: Significant differences in LA-GLS were found during both rhythms (SR and AF) between the thrombus group and control group: LA-GLS in SR: 14.3 ± 7.4% vs. 24.6 ± 9.0%, p < 0.001 and in AF: 11.4 ± 4.2% vs. 16.1 ± 5.0%, p = 0.045. ROC analysis revealed a threshold of 17.45% for the entire cohort (AUC 0.82, sensitivity: 84.6%, specificity: 63.6%, Negative Predictive Value (NPV): 94.3%) with additional rhythm-specific thresholds: 19.1% in SR and 13.9% in AF, and a threshold of 165 ms for APWD (AUC 0.90, sensitivity: 88.5%, specificity: 75.5%, NPV: 96.2%) as optimal discriminators of LAA-thrombus. Moreover, both LA-GLS and APWD correlated well with the established contractile LA-parameter LAA-Vel in TEE (r = 0.39, p < 0.001 and r = −0.39, p < 0.001, respectively). Conclusion: LA-GLS and APWD are valuable diagnostic predictors of left atrial thrombogenesis in patients with AF.

Low-Voltage-Area Ablation in Paroxysmal Atrial Fibrillation - Extended Follow-up Results of the VOLCANO Trial

BACKGROUND

The randomized controlled VOLCANO trial demonstrated comparable 1-year rhythm outcomes between patients with and without ablation targeting low-voltage areas (LVAs) in addition to pulmonary vein isolation among paroxysmal atrial fibrillation (PAF) patients with LVAs.

METHODS AND RESULTS

An extended-follow-up study of 402 patients enrolled in the VOLCANO trial with PAF, divided into 4 groups based on the results of voltage mapping: group A, no LVA (n=336); group B, LVA ablation (n=30); group C, LVA without ablation (n=32); and group D, incomplete voltage map (n=4). At 25 (23, 31) months after the initial ablation, AF/atrial tachycardia (AT) recurrence rates were 19% in group A, 57% in group B, 59% in group C, and 100% in group D. Recurrence rates were higher in patients with LVAs than in those without (group A vs. B+C, P<0.0001), and were comparable between those with and without LVA ablation (group B vs. C, P=0.83). Among patients who underwent repeat ablation, ATs were more frequently observed in patients with LVAs (Group B+C, 50% vs. A, 14%, P<0.0001). In addition, LVA ablation increased the incidence of AT development (group B, 71% vs. C, 32%, P<0.0001).

CONCLUSIONS

Patients with LVAs demonstrated poor long-term rhythm outcomes irrespective of LVA ablation. ATs were frequently observed in patients with LVAs, and LVA ablation might exacerbate the occurrence of iatrogenic ATs.

Atrial low voltage areas: A comparison between atrial fibrillation and sinus rhythm

BACKGROUND

Atrial fibrosis can promote atrial fibrillation (AF). Electroanatomic mapping (EAM) can provide information regarding local voltage abnormalities that may be used as a surrogate marker for fibrosis. Specific voltage cut-off values have been reproduced accurately to identify fibrosis in the ventricles, but these values are not well defined in atrial tissue.

METHODS

This study is a prospective single-center study. Patients with persistent AF referred for ablation were included. EAM was performed before ablation. We recorded bipolar signals, first in AF and later in sinus rhythm (SR). Two thresholds delimited low-voltage areas (LVA), 0.5 and 0.3 mV. We compared LVA extension between maps in SR and AF in each patient.

RESULTS

A total of 23 patients were included in the study. The percentage of points with voltage lower than 0.5 mV and 0.3 mV was significantly higher in maps in AF compared with maps in SR: 38.2% of points < 0.5 mV in AF vs. 22.9% in SR (p < 0.001); 22.3% of points < 0.3 mV in AF vs. 14% in SR (p < 0.001). Areas with reduced voltage were significantly larger in maps in AF (0.5 mV threshold, mean area in AF 41.3 ± 42.5 cm2 vs. 11.7 ± 17.9 cm2 in SR, p < 0.001; 0.3 mV threshold, mean area in AF 15.6 ± 22.1 cm2 vs. 6.2 ± 11.5 cm2 in SR, p < 0.001).

CONCLUSIONS

Using the same voltage thresholds, LVA extension in AF is greater than in SR in patients with persistent AF. These findings provide arguments for defining a different atrial fibrosis threshold based on EAM rhythm.

Electroanatomic voltage mapping for tissue characterization beyond arrhythmia definition: A systematic review

Three-dimensional (3D) reconstruction by means of electroanatomic mapping (EAM) systems, allows for the understanding of the mechanism of focal or re-entrant arrhythmic circuits, which can be identified by means of dynamic (activation and propagation) and static (voltage) color-coded maps. However, besides this conventional use, EAM may offer helpful anatomical and functional information for tissue characterisation in several clinical settings. Today, data regarding electromechanical myocardial viability, scar detection in ischaemic and nonischaemic cardiomyopathy and arrhythmogenic right ventricle dysplasia (ARVC/D) definition are mostly consolidated, while emerging results are becoming available in contexts such as Brugada syndrome and cardiac resynchronisation therapy (CRT) implant procedures. As part of an invasive procedure, EAM has not yet been widely adopted as a stand-alone tool in the diagnostic path. We aim to review the data in the current literature regarding the use of 3D EAM systems beyond the definition of arrhythmia.

How, When, and Why: High-Density Mapping of Atrial Fibrillation

High-density (HD) mapping presents opportunities to enhance delineation of atrial fibrillation (AF) substrate, improve efficiency of the mapping procedure without sacrificing safety, and afford new mechanistic insights regarding AF. Innovations in hardware, software algorithms, and development of novel multielectrode catheters have allowed HD mapping to be feasible and reliable. Patients to particularly benefit from this technology are those with paroxysmal AF in setting of preexisting atrial scar, persistent AF, and AF in the setting of complex congenital heart disease. The future will bring refinements in automated HD mapping including evolution of noncontact methodologies and artificial intelligence to supplant current techniques.

Left atrial voltage mapping: defining and targeting the atrial fibrillation substrate

Low atrial endocardial bipolar voltage, measured during catheter ablation for atrial fibrillation (AF), is a commonly used surrogate marker for the presence of atrial fibrosis. Low voltage shows many useful associations with clinical outcomes, comorbidities and has links to trigger sites for AF. Several contemporary trials have shown promise in targeting low voltage areas as the substrate for AF ablation; however, the results have been mixed. In order to understand these results, a thorough understanding of voltage mapping techniques, the relationship between low voltage and the pathophysiology of AF, as well as the inherent limitations in voltage measurement are needed. Two key questions must be answered in order to optimally apply voltage mapping as the road map for ablation. First, are the inherent limitations of voltage mapping small enough as to be ignored when targeting specific tissue based on voltage? Second, can conventional criteria, using a binary threshold for voltage amplitude, truly define the extent of the atrial fibrotic substrate? Here, we review the latest clinical evidence with regard to voltage-based ablation procedures before analysing the utility and limitations of voltage mapping. Finally, we discuss omnipole mapping and dynamic voltage attenuation as two possible approaches to resolving these issues.

High-resolution Mapping in Patients with Persistent AF

Ablation of AF through electrical isolation of the pulmonary veins is a well-established technique and a cornerstone in the ablation of AF, although there are a variety of techniques and ablation strategies now available. However, high numbers of patients are returning to hospital after ablation procedures such as pulmonary vein isolation (PVI). Scar tissue (as identified by contact voltage mapping) is found to be present in many of these patients, especially those with persistent AF and even those with paroxysmal AF. This scarring is associated with poor outcomes after PVI. Cardiac mapping is necessary to locate triggers and substrate so that an ablation strategy can be optimised. Multipolar mapping catheters offer more information regarding the status of the tissue than standard ablation catheters. A patient-tailored catheter ablation approach, targeting the patient-specific low voltage/fibrotic substrate can lead to improved outcomes.

Multimodality Imaging for Best Dealing With Patients in Atrial Arrhythmias

The management of atrial fibrillation (AF) is not only a clinical challenge but also an imaging challenge. The role of different imaging modalities to estimate the thromboembolic risk in AF is a key clinical question. The present review summarizes the advances of myocardial imaging in the stratification of thromboembolic risk, diagnosis, and management of left atrial thrombosis in patients with AF. These imaging techniques are also important for understanding arrhythmias and their consequences. It is becoming fundamental for guiding therapy. Still, large studies are required, but be sure that left atrial imaging will become more and more clinically fundamental.

Predictive factors for new-onset atrial fibrillation in acute coronary syndrome patients undergoing percutaneous coronary intervention

BACKGROUND

The aim of this study is to investigate the predictive factors for new-onset atrial fibrillation (AF) in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI).

METHODS

A total of 934 ACS patients admitted into the Department of Cardiology from February 2015 to February 2017 were collected. All patients were treated with PCI after admission and followed up for 1 year. Data of patients, such as age, gender, past medical history, dyslipidemia, cardiogenic shock, heart failure, medication, culprit vessel, echocardiographic characteristics and types of ACS were collected. Patients enrolled were divided into AF group and non-AF group according to whether there was new-onset AF or not. The clinical baseline data, coronary angiographic results and echocardiographic characteristics were compared between the two groups. The left atrial volume index (LAVI) and incidence rate of AF were compared using the histogram, and multivariate Logistic regression analyses were conducted for independent risk factors for new-onset AF in ACS patients undergoing PCI.

RESULTS

In terms of clinical baseline data and coronary angiographic results, the average age and proportions of female, hypertension, heart failure, cardiogenic shock and application of β-receptor blockers and antiarrhythmic drugs in AF group were significantly increased compared with those in non-AF group (P<0.05). In terms of echocardiographic characteristics, the mitral E peak, LAVI, and proportions of E/Em>15 and proportions of left ventricular ejection fraction (LVEF) <40% were significantly increased (P<0.05), but LVEF was obviously decreased (P<0.05) in AF group compared with those in non-AF group. According to multivariate Logistic regression analyses, cardiogenic shock, LAVI and age were independent risk factors for new-onset AF in ACS patients undergoing PCI. The comparison among patients with different LAVI showed that with the increase of LAVI, the incidence rate of AF was gradually increased.

CONCLUSIONS

Cardiogenic shock, LAVI and advanced age are independent predictive factors for new-onset AF in ACS patients undergoing PCI. The incidence rate of AF was gradually increased with the increase of LAVI.

Combination of doxorubicin liposomes with left atrial appendage radiofrequency catheter ablation to reduce post-ablation recovery of electrical conduction

Aims

To determine whether use of radiofrequency catheter ablation (RFCA) combined with intravenously administered liposomal doxorubicin (L-DOX) facilitates a reduction in the recovery of post-ablation electrical conduction.

Methods

Circumferential ablation was performed on the epicardial surface of the left atrial appendage (LAA) in New Zealand White rabbits, and L-DOX was then administered intravenously. Fluorescence spectrophotometry was used to assess reagent bio-distribution, while Western blots and immunohistochemistry were used to assess the localization of the apoptotic markers Bcl-2, Bax, and cleaved CASP3 in the LAA. Liver, kidney, and cardiac functions were also measured to evaluate the safety of this approach.

Results

At 1 week and 1 month after RFCA, a pacing electrocardiogram could not be detected in most of the rabbits that had received the combined RFCA and L-DOX therapy. L-DOX began to target the LAA on the second day after RFCA. L-DOX treatment increased the apoptosis of cardiomyocytes in the regions peripheral to the necrotic area induced by RFCA. Doxorubicin had some effect on liver and kidney function, but these effects were reversible and did not affect survival.

Conclusion

The present results provide evidence that L-DOX treatment can reduce the recovery of electrical conduction after RFCA therapy owing to L-DOX-induced apoptosis of cardiomyocytes in the ablated area and the proximal transition zone of the LAA.

Clinical scores used for the prediction of negative events in patients undergoing catheter ablation for atrial fibrillation

Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia in adults. Catheter ablation (CA) is one of the most important management strategies to reduce AF burden and AF-associated complications. In order to stratify the risk of adverse events and to predict treatment success in AF patients undergoing CA, several risk stratification scores had been developed during the last decade. The aim of this review is to provide an overview of the most important clinical risk scores predicting rhythm outcomes, electro-anatomical substrate and mortality in AF.

Association between PR interval prolongation and electro-anatomical substrate in patients with atrial fibrillation

Background

Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical routine. Left atrial (LA) electro-anatomical remodelling in AF patients indicates disease progression and is associated with poor therapeutic success. PR interval prolongation is associated with an increased risk for AF, however, the association between LA remodelling measured as low voltage areas (LVA) during catheter ablation and PR interval is unknown. The aim of this study was to investigate the association between PR interval prolongation and LVA in AF patients.

Methods

We studied 103 patients (62±12 years, 59% males, 34% persistent AF) undergoing first AF catheter ablation and presenting with sinus rhythm. PR interval prolongation was defined as PR >200ms and analysed in resting ECG before intervention. LVA were determined using high-density maps and defined as <0.5 mV.

Results

There were 24 patients (23%) with PR interval prolongation and 18 patients (17%) with LVA. There were significant correlations between PR prolongation with LVA, CHA₂DS₂-VASc score and eGFR (r² = 0.230, 0.216, and 0.307, all p<0.05). PR interval prolongation (OR 3.450, p = 0.024), persistent AF (OR 5.391, p = 0.002), and LA size (OR 1.117, p = 0.018) were significant predictors for LVA, while age (OR 1.072, p = 0.005), LVA (OR 3.450 p = 0.024) and eGFR (OR 0.962, p = 0.004) were associated with PR interval prolongation.

Conclusions

Beside persistent AF and LA size, PR interval prolongation might be useful for the prediction of electro-anatomical substrate in AF patients. Larger studies are needed to confirm these results.

Prediction of electro-anatomical substrate and arrhythmia recurrences using APPLE, DR-FLASH and MB-LATER scores in patients with atrial fibrillation undergoing catheter ablation

Arrhythmia recurrences after catheter ablation of atrial fibrillation (AF) cause intensive treatment costs. Left atrial electro-anatomical remodeling measured as low voltage areas (LVA) during catheter ablation indicates advanced disease stage and is associated with poor ablation success. The aim of this study was to analyze the prediction of LVA and arrhythmia recurrences using APPLE, DR-FLASH and MB-LATER scores. APPLE, DR-FLASH scores were calculated at baseline and MB-LATER at 3 months post-ablation in AF patients undergoing first catheter ablation. LVA was determined using high-density maps and defined as <0.5 mV. Early (ERAF, <3 months) and late (LRAF, 3–12 months) were analyzed during follow-up. The study population included 241 patients (age 64 ± 11 years, 59% males, 59% persistent AF, 27% LVA, 27% LRAF). LVA were significantly associated with recurrences (OR 2.081, p = 0.026). While on univariable analysis, all scores were significantly associated with LVA, on multivariable analysis only APPLE (OR 1.789, p < 0.001) and DR-FLASH (OR 2.144, p < 0.001) remained significant predictors. However, MB-LATER (OR 1.445, p = 0.034) and ERAF (OR 5.078, p < 0.001) remained associated with LRAF on the multivariable analysis. These results were validated in a subgroup of 873 patients (age 61 ± 10, 63% males, 39% persistent AF, 34% LRAF, 27% LVA) from The Leipzig Heart Center AF Ablation Registry. All scores were significantly associated with recurrences. However, ERAF was the most powerful predictor for later rhythm outcomes. Summarizing, a clinical score useful for prediction for both LVA and rhythm outcomes in AF patients remains a clinical unmet need.

Efficacy of sole pulmonary vein isolation in patients with nonparoxysmal atrial fibrillation without significant left atrium scar

BACKGROUND

Catheter ablation strategies for nonparoxysmal atrial fibrillation (NPAF) are in varied forms. The mechanisms that circumferential pulmonary vein isolation (CPVI) alone could achieve success in some of the patients with NPAF are not well studied. This study sought to assess the clinical outcome of only CPVI approach in NPAF patients without significant left atrium scar.

METHODS AND RESULTS

A total of 241 consecutive patients with NPAF undergoing an initial ablation procedure were studied. After CPVI, cavotricuspid isthmus ablation and direct current cardioversion, high-density atrial voltage mapping was performed during sinus rhythm. Transitional-voltage zone (TZ) was defined as 0.4-1.3 mV, and low-voltage zone (LVZ) as <0.4 mV. No LVZs were identified in 101 patients (41.9%), and only CPVI was performed. Among the patients without LVZs, single-procedure freedom from atrial fibrillation (AF)/atrial tachycardia was achieved in 73 patients (72%), while 28 patients (28%) had AF recurrence with mean follow-up of 29 ± 14 months. TZ index (TZi) was deduced by calculating the ratio of all TZ points over the total number of points and was found to be a univariate predictor of recurrence after a single procedure (P  =  0.047).

CONCLUSIONS

The CPVI alone strategy for patients with NPAF can be performed in highly selective patients without LVZs. TZi may reflect healthy extent of left atrium, which has trend toward the association with AF recurrence.

Rabbit model to simulate the residual conduction gaps after radiofrequency ablation on the anterior wall of left atrial appendage

PURPOSE

Radiofrequency ablation (RFA) is widely used to treat patients with atrial fibrillation (AF), but its recurrence rate is still high mainly due to pulmonary vein reconnection and residual conduction gaps. We aim to establish a rabbit model to simulate the residual conduction gaps after ablation.

METHODS

Sixty-nine adult New Zealand white rabbits were randomly assigned to six groups. RFA on the anterior wall of left atrial appendage (LAA) were performed with the ablation power from 6 to 21 W. The electrophysiological pacing and mapping technology was used to evaluate the bidirectional conduction of LAA. Histological study and fluorescence techniques were used to evaluate the effect of RFA and the accumulation of drug-loaded liposome on the loop ablation lesions of LAA.

RESULTS

Typical loop ablation lesions of LAA could be observed in vivo and vitro of rabbit models. Histological evaluation revealed coagulative necrosis on the loop ablation lesions. Electrical conduction between inside and outside loop lesions recovered after 1 or 2 weeks after initial unidirectional conduction block. The recurrence rates were significantly different among six groups with varying ablation powers (p < 0.05). Compared with exit conduction block, entrance conduction block was significantly different at 5 min after ablation (p = 0.02). IR-775-loaded liposomes were accumulated on the loop ablation lesions at 48 h after RFA.

CONCLUSIONS

RFA associated with electrophysiological pacing and mapping technology successfully established a novel rabbit model to simulate the residual conduction gaps after RFA.