Radiofrequency catheter ablation of accessory pathways in patients with Ebstein’s anomaly: At 8 years of follow-up

Ebstein's anomaly: an electrophysiological perspective

Ebstein's anomaly of the tricuspid valve (EA) is an uncommon congenital cardiac malformation. It can present with atrioventricular tachycardia (AVRT), atrioventricular nodal re-entrant tachycardia (AVNRT), atrial arrhythmias, and rarely with ventricular tachycardia. The 12-lead electrocardiogram (ECG) is critically important and often diagnostic even prior to an electrophysiology study (EPS). Due to its complex anatomy, it poses particular challenges for mapping and ablation, even for an experienced electrophysiologist. In this review, we aim to provide insight into the electrophysiological perspective of EA and an in-depth analysis of the various arrhythmias encountered in diverse clinical scenarios.

Two decades of experience on ablation in children with Ebstein's anomaly

INTRODUCTION

Accessory pathways are commonly seen due to delamination of tricuspid valve leaflets. In addition to accessory pathways, an enlarged right atrium due to tricuspid regurgitation and incisional scars creates substrates for atrial re-entries and ectopic tachycardia. We sought to describe our experience with catheter ablation in children with Ebstein's anomaly.

METHODS AND RESULTS

During the study period, of 89 patients diagnosed with Ebstein's anomaly, 26 (30.9%) of them who underwent 33 ablation procedures were included in the study. Accessory pathways were observed in the majority of procedures (n = 27), whereas atrial flutter was observed in five, atrioventricular nodal reentrant tachycardia in five, and atrial tachycardia in two procedures. Accessory pathways were commonly localised in the right posteroseptal (n = 10 patients), right posterolateral (n = 14 patients), septal (n = two patients), and left posteroseptal (n = one patient) areas. Multiple accessory pathways and coexistent arrhythmia were observed in six procedures. All ablation attempts related to the accessory pathways were successful, but recurrence was observed in five (19%) of the ablations. Ablation for atrial flutter was performed in five patients; two of them were ablated successfully. One of the atrial tachycardia cases was ablated successfully.

CONCLUSIONS

Ablation in patients with Ebstein's anomaly is challenging, and due to nature of the disease, it is not a rare occasion in this group of patients. Ablation of accessory pathways has high success, but also relatively high recurrence rates, whereas ablation of atrial arrhythmias has lower success rates, especially in operated patients.

Accessory pathway ablation in Ebstein anomaly: A challenging substrate

BACKGROUND

Catheter ablation of accessory pathways (APs) in Ebstein anomaly (EA) has been associated with a high recurrence risk.

OBJECTIVE

The purpose of this study was to compare outcomes of AP ablation in EA in an early (1990-2004) vs a recent (2005-2019) era and identify variables associated with recurrence.

METHODS

A retrospective review of all catheter ablations for supraventricular tachycardia in EA at our institution was performed.

RESULTS

We identified 76 patients with median (25th-75th quartiles) age 9 (2.6-13.3) years. Of these patients, 52 had AP alone, 12 had atrial flutter, 3 had atrioventricular nodal reentrant tachycardia, and 9 had AP plus at least 1 additional arrhythmia. Of the 61 patients with APs, a total of 78 separate APs were identified: 40 right-sided, 37 septal, and 1 left-sided. Acute success for AP first procedure was 89% and did not differ between early and recent eras (89% vs 88%; P = .48). However, 19 patients (31%) required repeat procedures (average 1.4 per patient) due to AP recurrence or ablation failure at first attempt. In comparison to early era, recent era ablations had significantly lower recurrence rates at 1 year (62% vs 19%; P = .005). At median follow-up of 2.5 (0.2-7) years, ultimate AP elimination after all procedures was 93%. Younger age at time of electrophysiological study (<2 vs 12-47 years: hazard ratio [HR] 7.3; P = .003) and ablation era (early era vs recent era: HR 3.65; P = .009) predicted recurrence.

CONCLUSION

Outcomes for AP ablation in patients with EA have improved, but there is still a relatedly high recurrence risk requiring repeat procedures.

Electroanatomic Mapping-Guided Catheter Ablation of Supraventricular Tachycardia in Children with Ebstein's Anomaly

In Ebstein's anomaly (EA), tachycardia substrates are complex, and accessory pathway (AP) ablations are often challenging. This study demonstrates the utility of the EnSite Velocity system (St. Jude Medical, St Paul, MN) in the catheter ablation of supraventricular tachycardia in children with EA. Twenty patients [Female/Male = 8/12, median age 11.5 years (2.6-18)] with EA who underwent catheter ablation guided by the EnSite Velocity system between December 2011 and December 2016 were retrospectively evaluated. Five patients had severe EA, and two of them were at Fontan palliation pathway. The most common indications for ablations were palpitations/syncope and treatment-resistant arrhythmias. Thirty-one tachycardia substrate foci (21 manifest AP, 2 concealed AP, 4 Mahaim AP, 3 focal atrial tachycardias, and 1 typical atrioventricular nodal reentrant tachycardia) were detected in 20 patients. There were multiple tachycardia substrates in 11 patients (55%). The patient-based acute procedure success rate was 19/20 (95%), and the tachycardia-based success rate was 30/31 (97%). The mean procedure time was 170 ± 43 min (90-265). Fluoroscopy was not used in 15 (75%) patients. The mean fluoroscopy time in the remaining five patients was 3.6 ± 2.9 min (0.7-7.8). During a mean follow-up of 35.1 ± 20.3 months (6-60), tachycardia recurred in four patients (4/19, 21%). No complications were seen. Catheter ablation of arrhythmias can be performed effectively and safely in pediatric EA patients by using a limited fluoroscopic approach with the help of electroanatomical mapping systems. However, the rate of tachycardia recurrence at follow-up remains high.

Outcomes of Ebstein's Anomaly Patients Treated with Tricuspid Valvuloplasty or Tricuspid Valve Replacement: Experience of a Single Center

Background:

The incidence of Ebstein's anomaly is extremely low, and except for the Mayo Clinic, no cardiac center has reported on a sufficient number of patients. The aim of our study was to report the outcomes of Ebstein's anomaly patients treated with tricuspid valvuloplasty (TVP) or tricuspid valve replacement (TVR).

Methods:

TVP or TVR was performed in 245 patients from July 2006 to April 2016. We reviewed patients' records and contacted patients via outpatient service and over the telephone.

Results:

The mean follow-up time was 43.6 ± 32.6 months, and 224 (91.4%) patients underwent follow-up. The mean operative age was 31.2 ± 15.7 years. TVR was performed in 23 patients, and TVP was performed in 201 patients. The 30-day mortality rate was 1.3%, and the overall survival rate was 97.9% at 5 and 10 years. The early mortality rate of the TVP group was lower than that of the TVR group (0.5% vs. 8.7%, P = 0.028), and the overall mortality rate of the TVP group was lower than that of the TVR group, without statistical significance (1.0% vs. 8.7%). After propensity score matching, the rates of mortality and New York Heart Association class ≥ III were lower in the TVP group than those in the TVR group without statistical significance. Seven patients with Type B Wolff-Parkinson-White (WPW) syndrome underwent one-stage surgery, and arrhythmias disappeared. Six patients suffered from episodes of left ventricular outflow tract obstruction (LVOTO) during surgery. Severe LVOTO could be treated with reoperation of the atrialized right ventricle.

Conclusions:

Ebstein's anomaly patients treated with TVP or TVR can experience optimal outcomes with midterm follow-up. However, TVP should be the first-choice treatment. Optimal outcomes can be obtained from one-stage operation in patients with Type B WPW syndrome. Severe LVOTO during surgery might be related to improper operation of the atrialized right ventricle.