Good responders to catheter ablation for long-standing persistent atrial fibrillation: Clinical and genetic characteristics

Genetically Based Atrial Fibrillation: Current Considerations for Diagnosis and Management

Atrial fibrillation (AF) is the most common atrial arrhythmia and is subcategorized into numerous clinical phenotypes. Given its heterogeneity, investigations into the genetic mechanisms underlying AF have been pursued in recent decades, with predominant analyses focusing on early onset or lone AF. Linkage analyses, genome wide association studies (GWAS), and single gene analyses have led to the identification of rare and common genetic variants associated with AF risk. Significant overlap with genetic variants implicated in dilated cardiomyopathy syndromes, including truncating variants of the sarcomere protein titin, have been identified through these analyses, in addition to other genes associated with cardiac structure and function. Despite this, widespread utilization of genetic testing in AF remains hindered by the unclear impact of genetic risk identification on clinical outcomes and the high prevalence of variants of unknown significance (VUS). However, genetic testing is a reasonable option for patients with early onset AF and in those with significant family history of arrhythmia. While many knowledge gaps remain, emerging data support genotyping to inform selection of AF therapeutics. In this review we highlight the current understanding of the complex genetic basis of AF and explore the overlap of AF with inherited cardiomyopathy syndromes. We propose a set of criteria for clinical genetic testing in AF patients and outline future steps for the integration of genetics into AF care. This article is protected by copyright. All rights reserved.

Catheter Ablation of Atrial Fibrillation in Heart Failure: from Evidences to Guidelines

PURPOSE OF REVIEW

Catheter ablation of atrial fibrillation in heart failure seems to be the way to improve the quality of life, life expectance, and prognosis. In this review, we outline the growing role of this therapy and which patients can benefit from it.

RECENT FINDINGS

While previous studies comparing rate control and rhythm control had not demonstrated the superiority of rhythm control in the prognosis of patients with atrial fibrillation and heart failure, recent findings seem to demonstrate that catheter ablation of atrial fibrillation reduces mortality and hospitalization for heart failure and improves the quality of life, when compared to medical therapy alone. An early rhythm-control strategy in atrial fibrillation may reduce cardiovascular death, stroke, hospitalization for HF, or acute coronary syndrome. Catheter ablation in heart failure is an effective and safe solution to obtain a rhythm control and, therefore, to improve outcomes. A better selection of the patients could help to avoid futile procedures and to identify patients requiring a closer follow-up, to redo procedures, or the addition of antiarrhythmic drugs.

A new machine learning approach for predicting likelihood of recurrence following ablation for atrial fibrillation from CT

OBJECTIVE

To investigate left atrial shape differences on CT scans of atrial fibrillation (AF) patients with (AF+) versus without (AF-) post-ablation recurrence and whether these shape differences predict AF recurrence.

METHODS

This retrospective study included 68 AF patients who had pre-catheter ablation cardiac CT scans with contrast. AF recurrence was defined at 1 year, excluding a 3-month post-ablation blanking period. After creating atlases of atrial models from segmented AF+ and AF- CT images, an atlas-based implicit shape differentiation method was used to identify surface of interest (SOI). After registering the SOI to each patient model, statistics of the deformation on the SOI were used to create shape descriptors. The performance in predicting AF recurrence using shape features at and outside the SOI and eight clinical factors (age, sex, left atrial volume, left ventricular ejection fraction, body mass index, sinus rhythm, and AF type [persistent vs paroxysmal], catheter-ablation type [Cryoablation vs Irrigated RF]) were compared using 100 runs of fivefold cross validation.

RESULTS

Differences in atrial shape were found surrounding the pulmonary vein ostia and the base of the left atrial appendage. In the prediction of AF recurrence, the area under the receiver-operating characteristics curve (AUC) was 0.67 for shape features from the SOI, 0.58 for shape features outside the SOI, 0.71 for the clinical parameters, and 0.78 combining shape and clinical features.

CONCLUSION

Differences in left atrial shape were identified between AF recurrent and non-recurrent patients using pre-procedure CT scans. New radiomic features corresponding to the differences in shape were found to predict post-ablation AF recurrence.

The molecular genetic basis of atrial fibrillation

As the most common cardiac arrhythmia, atrial fibrillation (AF) is a major risk factor for stroke, heart failure, and premature death with considerable associated costs. However, no available treatment options have optimal benefit-harm profiles currently, reflecting an incomplete understanding of the biological mechanisms underlying this complex arrhythmia. Recently, molecular epidemiological studies, especially genome-wide association studies, have emphasized the substantial genetic component of AF etiology. A comprehensive mapping of the genetic underpinnings for AF can expand our knowledge of AF mechanism and further facilitate the process of locating novel therapeutics for AF. Here we provide a state-of-the-art review of the molecular genetics of AF incorporating evidence from linkage analysis and candidate gene, as well as genome-wide association studies of common variations and rare copy number variations; potential epigenetic modifications (e.g., DNA methylation, histone modification, and non-coding RNAs) are also involved. We also outline the challenges in mechanism investigation and potential future directions in this article.

Safety, long-term outcomes and predictors of recurrence following a single catheter ablation procedure for atrial fibrillation

Background: Data regarding long-term outcomes of atrial fibrillation (AF) catheter ablation are limited. This study evaluated the safety, long-term efficacy and predictors of recurrence after a single left atrial ablation procedure in patients with paroxysmal (PAF) and non-paroxysmal AF (NPAF). Methods: Data from 520 patients (354 males, mean age 57.08 ± 11.33 years) with PAF (n = 356, 68.5%) or NPAF (n = 164, 31.5%) who underwent a single radiofrequency ablation procedure were analysed. Across the NPAF group, there were 143 (27.5%) patients with persistent AF and 21 (4%) with long-standing persistent AF. The mean follow-up period was 39.05 ± 20.83 months (range 19-60 months). Results: Arrhythmia recurrence was observed in 102/356 (28.7%) of PAF patients and in 63/164 (38.4%) of NPAF patients. In patient with PAF, sinus rhythm maintenance was observed in 76.9%, 73% and 71.3% of patients at 1, 2 and 5 years of follow-up, respectively. In patients with NPAF, sinus rhythm was maintained in 68.7%, 63.4% and 61.6% of patients at 1, 2 and 5 years of follow-up, respectively. Independent predictors of AF recurrence were left atrial diameter (OR 1.15, 95% CI 1.10-1.21, p < 0.01) as well as early arrhythmia recurrence during the blanking period of 3 months after the procedure (OR 8.13, 95% CI 5.10-12.82, p < 0.01). Major complications were observed in 11 patients (2.1%). Conclusions: Long-term arrhythmia-free survival rates remain high among PAF and NPAF patients after a single catheter ablation procedure. Left atrial diameter and early arrhythmia recurrence were independent predictors of late arrhythmia recurrence in both PAF and NPAF patients.

Catheter Ablation of Long-standing Persistent Atrial Fibrillation: a Reckless Challenge or a Way to Real Cure?

Long-standing persistent atrial fibrillation (L-PeAF) is a category in which rhythm control is attempted while atrial fibrillation (AF) is maintained for more than 1 year. Because AF is a progressive disease and L-PeAF accompanies significant electrical and structural remodeling of atria, it is difficult to restore and maintain sinus rhythm in patients with L-PeAF. Nonetheless, the rhythm outcome is being increasingly improved by the development of sophisticated mapping devices, highly efficient catheters, and evidence-based ablation strategies, and the rational choice of patient selection criteria. This review discusses the evolution of the rhythm control outcome of L-PeAF and its future direction of development.

A Genetic Risk Score for Atrial Fibrillation Predicts the Response to Catheter Ablation

Background and Objectives

The association of susceptibility loci for atrial fibrillation (AF) with AF recurrence after ablation has been reported, although with controversial results. In this prospective cohort analysis, we aimed to investigate whether a genetic risk score (GRS) can predict the rhythm outcomes after catheter ablation of AF.

Methods

We determined the association between 20 AF-susceptible single nucleotide polymorphisms (SNPs) and AF recurrence after catheter ablation in 746 patients (74% males; age, 59±11 years; 56% paroxysmal AF). A GRS was calculated by summing the unweighted numbers of risk alleles of selected SNPs. A Cox proportional hazard model was used to identify the association between the GRS and risk of AF recurrence after catheter ablation.

Results

AF recurrences after catheter ablation occurred in 168 (22.5%) subjects with a median follow-up of 23 months. The GRS was calculated using 5 SNPs (rs1448818, rs2200733, rs6843082, rs6838973 at chromosome 4q25 [PITX2] and rs2106261 at chromosome 16q22 [ZFHX3]), which showed modest associations with AF recurrence. The GRS was significantly associated with AF recurrence (hazard ratio [HR] per each score, 1.13; 95% confidence interval [CI], 1.03–1.24). Patients with intermediate (GRS 4–6) and high risks (GRS 7–10) showed HRs of 2.00 (95% CI, 0.99–4.04) and 2.66 (95% CI, 1.32–5.37), respectively, compared to patients with low risk (GRS 0–3).

Conclusions

Our novel GRS using 5 AF-susceptible SNPs was strongly associated with AF recurrence after catheter ablation in Korean population, beyond clinical risk factors. Further efforts are warranted to construct a generalizable, robust genetic prediction model which can guide the optimal treatment strategies.

Genotype-phenotype associations in atrial fibrillation: meta-analysis

PURPOSE

Genome-wide association studies have identified several single-nucleotide polymorphisms (SNPs) associated with atrial fibrillation (AF). The relationship between SNPs and the incidence of stroke, heart failure, and the recurrence rate of AF after cardioversion has been reported. This meta-analysis focuses on the genotype-phenotype associations in AF.

METHODS

We searched PubMed/Medline and Embase for literature providing the phenotypic parameters and genotypes of RS10033464, RS13376333, RS2106261, RS2200733, and RS7193343. We selected literature published in English and reviewed the full text of included studies to perform a meta-analysis.

RESULTS

Fifteen papers, and 7034 patients with AF, were included. The mean risk gene frequency of the investigated variants was between 12 and 43%. The mean age of patients was between 50 and 70 and 70-80% of them were male. The stroke and heart failure frequencies in AF patients with RS2200733 were 10 and 7%, respectively. There was no significant difference in left ventricular ejection fraction and left ventricular end-diastolic diameter for all risk genotypes. For the AF recurrence after cardioversion treatment with direct current electric conversion, catheter ablation therapy, and anti-arrhythmic drugs. The early AF recurrence rate was 46% in RS10033464 and RS13376333 patients, and the late AF recurrence rate was 53% in RS2200733 patients.

CONCLUSIONS

Pooled analysis showed a significantly high prevalence of stroke (10%) in RS2200733 AF patients. AF patients with the studied SNPs had preserved left ventricular systolic function (i.e., ejection fraction greater than 50%). AF patients with RS10033464 presented larger left atrium diameter (44 mm (95% CI 42.02-45.98)) than those with other SNPs. The late AF recurrence rate was highest in RS2200733 patients (53% (95% CI 0.43-0.64)). This study aids our understanding of the existing genetic findings and the function-altering "strongest" SNPs.

Maintenance of low inflammation level by the ZFHX3 SNP rs2106261 minor allele contributes to reduced atrial fibrillation recurrence after pulmonary vein isolation

INTRODUCTION

The single nucleotide polymorphism (SNP) rs2106261 in the transcription factor gene ZFHX3 (16q22), a major regulator of inflammation, has been reported linking to atrial fibrillation (AF) by genome-wide association studies. Inflammation is known to be a strong predictor of atrial fibrillation recurrence after ablation, so we examined the association of the ZFHX3 SNP rs2106261 to inflammation marker expression and recurrence after AF ablation.

METHODS

We genotyped ZFHX3 SNP rs2106261 and compared the minor (T) allele frequency between 362 paroxysmal AF (PAF) patients underwent pulmonary vein isolation (PVI) and 627 non-AF controls. We also analyzed associations between ZFHX3 SNP rs2106261 genotype and recurrence rate after pulmonary vein isolation and the inflammation markers.

RESULTS

The minor (T) allele frequency of the ZFHX3 SNP rs2106261 was significantly higher in AF patients than non-AF controls (odds ratio 1.52, p = 2.2×10-5). Multivariable analysis revealed that the minor allele (T) decreased AF recurrence rate after pulmonary vein isolation (hazard ratio 0.53, p = 0.04). Further, neutrophil/lymphocyte (N/L) ratio, C-reactive protein (CRP), and interleukin-6 (IL-6) expression levels were lower in PAF patients with the ZFHX3 SNP rs2106261 minor allele (TT+TC) than in CC patients (N/L ratio: CC 2.22 ± 0.08, TT+TC 1.98 ± 0.06, p = 0.018; CRP: CC 0.103 ± 0.009 mg/dl, TT+TC 0.076 ±0.007 mg/dl, p = 0.016; IL-6: CC 60.3 ± 3.0 pg/ml, TT+TC 52.8 ± 2.3 pg/ml, p = 0.04).

CONCLUSIONS

The ZFHX3 SNP rs2106261 minor allele is associated with lower AF recurrence rate after pulmonary vein isolation. Low baseline inflammation conferred by this allele may reduce AF recurrence risk.

Predictors of arrhythmia recurrence in patients with heart failure undergoing left atrial ablation for atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) ablation is increasingly used in patients with reduced left ventricular ejection fraction (LVEF). The aim of the present study was to evaluate the long-term results of a single radiofrequency catheter ablation procedure in heart failure (HF) patients with AF.

HYPOTHESIS

We tested the hypothesis that left atrial ablation is an effective therapeutic modality in patients with heart failure.

METHODS

Our study included HF patients with LVEF <50% who underwent catheter ablation for AF at our department between January 2010 and March 2017. All patients underwent our institution's protocol for follow-up post-ablation.

RESULTS

The study enrolled a total of 38 patients (mean age, 54.1 ± 12.2 years; 28 [73.7%] males; mean LVEF, 38.2% ± 6.3%). After a mean follow-up period of 38.2 months (range, 5-92 months), 28 patients (73.7%) were free from arrhythmia recurrence. In multivariate analysis, early arrhythmia recurrence (P = 0.03) and amiodarone antiarrhythmic drug administration (P = 0.003) remained independent predictors of arrhythmia recurrence.

CONCLUSIONS

The main findings of this study are that (1) a single radiofrequency catheter ablation procedure is an effective and safe modality for AF in patients with concomitant HF; (2) after a mean 3.3 years of follow-up, 73.7% of HF patients remained in sinus rhythm; and (3) early arrhythmia recurrence was a significant predictor of arrhythmia recurrence after the blanking period.

Association of atrial fibrillation susceptibility genes, atrial fibrillation phenotypes and response to catheter ablation: a gene-based analysis of GWAS data

Background

Previous studies have suggested PITX2, KCNN3 and ZFHX3 as atrial fibrillation (AF) susceptibility genes. Single common genetic polymorphisms of those genes have been linked with AF phenotypes and rhythm outcome of AF catheter ablation although their mechanisms remain elusive. New gene-based association tests may help clarifying genotype–phenotype correlations. Therefore, we hypothesized that PITX2, KCNN3 and ZFHX3 associate with left atrial enlargement and persistent AF and subsequently with ablation outcome.

Methods and results

Samples from 660 patients with paroxysmal (n = 370) or persistent AF (n = 290) undergoing AF catheter ablation were genotyped for ~1,000,000 SNPs. Gene-based association was investigated using two different gene-based association tests (VEGAS, minSNP). Among the three candidate genes, only ZFHX3 associated with left atrial dilatation and AF recurrence after catheter ablation.

Conclusion

This study suggests a contribution of ZFHX3 to AF remodeling and response to therapy. Future and larger studies are necessary to replicate and apply these findings with an emphasis on designing AF pathophysiology-based multi-locus risk scores.

Does Additional Electrogram-Guided Ablation After Linear Ablation Reduce Recurrence After Catheter Ablation for Longstanding Persistent Atrial Fibrillation? A Prospective Randomized Study

Background

Although circumferential pulmonary vein isolation (CPVI) catheter ablation may not be sufficient for long‐standing persistent atrial fibrillation (L‐PeAF), it is not clear which ablation strategy is beneficial in addition to CPVI. We sought to investigate whether additional complex fractionated atrial electrogram (CFAE)‐guided ablation improves clinical outcomes in L‐PeAF patients who exhibit continuous atrial fibrillation (AF) after CPVI and linear ablation (Line).

Methods and Results

This study enrolled 137 L‐PeAF patients (71.4% male, 61.6±10.9 years old) who underwent radiofrequency catheter ablation. We conducted CPVI+Line based on the Dallas lesion set (posterior box+anterior line) after baseline CFAE mapping in all patients. If AF was defragmented (terminated or changed to atrial tachycardia), the procedure was stopped (AF‐Defrag group, n=29). If AF was maintained after CPVI+Line, we mapped the CFAE again and randomly assigned the patient to the CPVI+Line group (n=54) or the additional CFAE ablation group (CPVI+Line+CFAE group, n=54). L‐PeAF was defragmented during CPVI+Line in 21.2% of patients (29/137, AF‐Defrag group). The mean CFAE cycle length was prolonged (P<0.001), and CFAE area (CFAE cycle length <120 milliseconds) was reduced (P<0.001) after CPVI+Line in the remaining patients. Procedure time was longer in the CPVI+Line+CFAE group than the CPVI+Line group (P=0.023), but procedure‐related complication rates did not vary. During 22.3±13.2 months of follow‐up, the clinical recurrence rates were 17.2% in the AF‐Defrag group, 18.5% in the CPVI+Line group, and 32.1% in the CPVI+Line+CFAE group (log rank, P=0.166).

Conclusions

Although CPVI+Line reduces and localizes CFAE area, additional CFAE ablation after CPVI+Line does not improve the clinical outcomes of catheter ablation in patients with L‐PeAF.