Recurrence of symptomatic atrial fibrillation after successful catheter ablation of atrioventricular accessory pathways: a multivariate regression analysis

Long-Term Follow-Up In Paroxysmal Atrial Fibrillation Patients With Documented Isolated Trigger

Aims

Supraventricular tachycardias may trigger atrial fibrillation (AF). The aim of the study was to evaluate the prevalence of supraventricular tachycardia (SVT) inducibility in patients referred for AF ablation and to evaluate the effects of SVT ablation on AF recurrences.

Methods and results

249 patients (mean age: 54 ± 14 years) referred for paroxysmal AF ablation were studied. In all patients, only AF relapses had been documented in the clinical history. 47 patients (19%; mean age: 42 ± 11 years) had inducible SVT during the electrophysiological study and underwent an ablation targeted only at SVT suppression. Ablation was successful in all 47 patients. The ablative procedures were: 11 slow-pathway ablations for atrioventricular nodal re-entrant tachycardia; 6 concealed accessory pathway ablations for atrioventricular re-entrant tachycardia; 17 focal ectopic atrial tachycardia ablations; 13 with only one arrhythmogenic pulmonary vein. No recurrences of SVT were observed during the follow-up (32 ± 18 months). 4 patients (8.5%) showed recurrence of at least one episode of AF. Patients with inducible SVT had less structural heart disease and were younger than those without inducible SVT.

Conclusion

A significant proportion of candidates for AF ablation are inducible for an SVT. SVT ablation showed a preventive effect on AF recurrences. Those patients should be selected for simpler ablation procedures tailored only to the triggering arrhythmia suppression.

Left atrial structure and function predictors of recurrent fibrillation after catheter ablation: a systematic review and meta-analysis

BACKGROUND

Catheter ablation (CA) has become a conventional treatment for atrial fibrillation (AF), but remains with high recurrence rate. The aim of this meta-analysis was to determine left atrial (LA) structure and function indices that predict recurrence of AF.

METHODS

We systematically searched PubMed-Medline, EMBASE, Scopus, Google Scholar and the Cochrane Central Registry, up to September 2017 in order to select clinical trials and observational studies which reported echocardiographic predictors of AF recurrence after CA. Eighty-five articles with a total of 16 126 patients were finally included.

RESULTS

The pooled analysis showed that after a follow-up period of 21 ± 12 months, patients with AF recurrence had larger LA diameter with weighted mean difference (WMD: 2·99 ([95% CI 2·50-3·47], P<0·001), larger LA volume index (LAVI) maximal and LAVI minimal (P<0·0001 for both), larger LA area (P<0·0001), lower LA strain (P<0·0001) and lower LA total emptying fraction (LA EF) (P<0·0001) compared with those without AF recurrence. The most powerful LA predictors (in accuracy order) of AF recurrence were as follows: LA strain <19% (OR: 3·1[95% CI, -1.3-10·4], P<0·0001), followed by LA diameter ≥50 mm (OR: 2·75, [95% CI 1·66-4·56,] P<0·0001), and LAVmax >150 ml (OR: 2·25, [95% CI, 1.1-5·6], P = 0·0002).

CONCLUSIONS

Based on this meta-analysis results, a dilated left atrium with diameter more than 50 mm and volume above 150 ml or myocardial strain below 19% reflect an unstable LA that is unlikely to hold sinus rhythm after catheter ablation for atrial fibrillation.

The feasibility and correlation of atrial fibrillation vulnerability test to the indices of atrial substrates using atrial burst decremental pacing

Pulmonary vein isolation and atrial substrate modification using catheter ablation have been developed as a standard treatment for atrial fibrillation (AF). However, the standard end-point for these procedures is still not well established. This study aimed to investigate the characteristics among positive and negative AF vulnerability patients with normal structural heart, in order to define the endpoint of the atrial substrate modification. Fifty supraventricular tachycardia patients with normal heart structure referred for electrophysiological study and catheter ablation were enrolled. After eliminating the underling arrhythmias, the basic cycle length, effective refractory period of the right atrium, and the P wave indices in 12-lead electrocardiograms were measured. The AF vulnerability test was performed by atrial burst decremental pacing with a pacing cycle length decreasing from 290 ms to 200 ms. The AF vulnerability test was considered as positive when the duration of the induced AF or atrial tachyarrhythmias (ATs) was longer than 10 seconds. The parameters of atrial substrates were compared between patients with positive and negative values of the AF vulnerability test. ATs or AF were induced in 24 (48%) patients. Among these patients, 12 (24%) induced ATs or AF were found to be sustained (duration more than 10 seconds). However, only two of these patients could reproduce the positive result after 10 minutes of the first induced protocol. Comparing the patient baseline characteristics, P wave characteristics and cardiac echo parameters, there were no significant differences between the positive and negative AF vulnerability groups. In conclusion, AF and ATs could be induced in patients with a structurally normal heart. The traditional clinical indices of atrial substrates were not significantly different between the positive and negative AF vulnerability patients. Protocols other than atrial burst decremental pacing should be investigated to evaluate the endpoint of the atrial substrate modification.

[Recurrence of atrial fibrillation after successful radiofrequency catheter ablation of accessory pathway in patients with Wolff-Parkinson-White syndrome]

INTRODUCTION

Paroxysmal atrial fibrillation (AF) occurs in 11.5-39% of the patients with Wolff-Parkinson-White (WPW) syndrome and frequently, but not always, disappears after successful accessory pathway (AP) ablation.

OBJECTIVE

To determine AF recurrence rate, time to AF recurrence and predictors of AF recurrence after radiofrequency (RF) catheter-ablation of AP in WPW-patients with AF.

METHODS

Data from 245 consecutive patients with WPW-syndrome who underwent RF catheter-ablation of AP were analysed. A total of 52 patients (43 men, mean age: 42.5 +/- 14.1 years) with preablation history of spontaneous AF were followed up after definitive AP ablation. At baseline, structural heart disease and comorbidities were diagnosed in 19.2% and 21.2% of the patients, respectively.

RESULTS

During the follow-up of 5.2-3.7 years, 3 patients (5.7%) died; one of these patients, previously known for recurrent AF, died from ischaemic stroke. Symptomatic recurrence of AF was detected in 9 of 52 patients (17.3%). In 66.7% of these patients, AF recurrence was identified in the first year following the procedure. Kaplan-Meier analysis demonstrated that freedom from recurrent AF after 3 months was 94.2%, after 1 year 87.5% and after 4 years 84.3%. Univariate analysis showed that older age (p = 0.023), presence of structural heart disease (p = 0.05) and dilated left atrium (p = 0.013) were significantly related to AF recurrence. However, using multivariate Cox regression, older age was the only independent predictor of AF recurrence (HR = 2.44 for every life decade; p = 0.006). Analysis of ROC curves showed that, after the age of 36, the risk of AF recurrence abruptly increased.

CONCLUSION

Symptomatic recurrence of AF was detected in 17% of WPW-patients after definite RF ablation of AP. The time-dependent occurrence of AF recurrences and age-dependent increase in the rate of AF recurrence were identified. Closer follow-up and/or extension of drug therapy in older patients, at least in the first year after the procedure, seem prudent.

Inducibility of atrial fibrillation during electrophysiologic evaluation is associated with increased dispersion of atrial refractoriness

The impact of atrial dispersion of refractoriness (Disp_A) in the inducibility and maintenance of atrial fibrillation (AF) has not been fully resolved.

AIM

To study the Disp_A and the vulnerability (A_Vuln) for the induction of self-limited (<60 s) and sustained episodes of AF.

METHODS AND RESULTS

Forty-seven patients with paroxysmal AF (PAF): 29 patients without structural heart disease and 18 with hypertensive heart disease. Atrial effective refractory period (ERP) was assessed at five sites--right atrial appendage and low lateral right atrium, high interatrial septum, proximal and distal coronary sinus. We compared three groups: group A - AF not inducible (n=13); group B - AF inducible, self-limited (n=18); group C - AF inducible, sustained (n=16). Age, lone AF, hypertension, left atrial and left ventricular (LV) dimensions, LV systolic function, duration of AF history, atrial flutter/tachycardia, previous antiarrhythmics, and Disp_A were analysed with logistic regression to determine association with A_Vuln for AF inducibility. The ERP at different sites showed no differences among the groups. Group A had a lower Disp_A compared to group B (47+/-20 ms vs 82+/-65 ms; p=0.002), and when compared to group C (47+/-20 ms vs 80+/-55 ms; p=0.008). There was no significant difference in Disp_A between groups B and C. By means of multivariate regression analysis, the only predictor of A_Vuln was Disp_A (p=0.04).

CONCLUSION

In patients with PAF, increased Disp_A represents an electrophysiological marker of A_Vuln. Inducibility of both self-limited and sustained episodes of AF is associated with similar values of Disp_A. These findings suggest that the maintenance of AF is influenced by additional factors.

Electrophysiologic and electrocardiographic characteristics of focal atrial tachycardia arising from superior tricuspid annulus

OBJECTIVES

This study describes the electrophysiologic and electrocardiographic characteristics of focal atrial tachycardia (AT) arising from superior tricuspid annulus in six (1.9%) patients of a consecutive series of 320 patients.

METHODS

Six patients (mean age 42 +/- 22 years) with a mean cycle length of 326 ms of a consecutive series of 320 patients undergoing radiofrequency ablation for focal AT were mapped.

RESULTS

During electrophysiologic study, tachycardia could be induced in five patients with programmed atrial extrastimuli while a spontaneous onset and offset with 'warm-up and cool-down' phenomenon was seen in the other patient. During tachycardia, P-wave morphology in Lead I, II, III and aVF was upright in all the six patients. The precordial leads were dominantly negative or isoelectric in V(1)-V(2) and positive in V(5)-V(6) with a transition at V(3) or V(4). Moreover, the tachycardia was sensitive to intravenous administration of adenosine triphosphate in five of six patients.

CONCLUSIONS

Radiofrequency ablation was performed successfully in all patients (mean 4.5 +/- 1.2 applications). No recurrence of AT was observed after a mean follow-up of 8 +/- 6 months. Thus, AT arising from superior tricuspid annulus is rare. Radiofrequency ablation of this kind of AT is safe and effective.

Atrial vulnerability is a major mechanism of paroxysmal atrial fibrillation in patients with Wolff–Parkinson–White syndrome

Atrioventricular re-entrant tachycardia is the most common form of tachycardia in patients with Wolff-Parkinson-White (WPW) syndrome where one or more accessory pathways are present between atria and ventricles. Paroxysmal atrial fibrillation (PAF) is also a relatively common form of tachycardia in these patients. The mechanisms of PAF in patients with WPW syndrome are not completely understood. Previous studies have mainly focused on the role of accessory pathways in the development of PAF. However, up to 24% of patients still experience PAF after successful ablation of accessory pathways by surgical incision or radiofrequency catheter ablation techniques. We hypothesized that there are two primary mechanisms involved in the pathogenesis of PAF in patients with WPW syndrome. One is related to the accessory pathways that predispose the atria to fibrillation; the other is increased atrial vulnerability that is independent of the accessory pathways. Clarification of these mechanisms is critical in developing more effective means for the prevention or treatment of PAF in patients with WPW syndrome.