Catheter Ablation of Right Ventricular Endocavitary Arrhythmias

Abstract

Background: Right ventricular (RV) endocavitary arrhythmias remain poorly characterized.

Objectives: The purpose of this study was to define the clinical presentation, ablation outcomes, and long-term prognosis of RV endocavitary arrhythmias.

Methods: Among 3,873 patients undergoing ventricular arrhythmia ablation between 2013 and 2025, 53 (1.4%) were included (mean age 45.4 ± 16.9 years, 64% male, mean left ventricular ejection fraction 54 ± 11%).

Results: Forty-three (81%) had structurally normal hearts and 10 (19%) had nonischemic cardiomyopathy, including 7 with premature ventricular contraction (PVC)-mediated cardiomyopathy and 3 with idiopathic nonischemic cardiomyopathy. Ablation indications included PVCs (n = 25), PVC-triggered ventricular fibrillation (VF) (n = 20), and ventricular tachycardia (n = 8). PVC QRS duration independently predicted developing PVC-mediated cardiomyopathy (P = 0.02). PVCs-triggering VF had shorter coupling intervals (CIs) (320 [295-358] vs 440 [400-470] ms; P < 0.05) and more frequently originated at the lateral moderator band (MB) (P = 0.03), where they also had shorter CIs than medial MB PVCs (P = 0.01). Ablation targets included the MB (n = 47), anterior papillary muscle (PM) (n = 3), inferior PM (n = 2), and conus PM (n = 1). Postablation increase in sinus rhythm QRS duration (98 [84-102] to 102 [90-114] ms; P < 0.01), V1 intrinsicoid deflection (22 [18-27] to 26 [20-95] ms; P < 0.01), and new right bundle branch block (15% of patients) did not translate into RV dysfunction or worsening tricuspid valve function. Radiofrequency energy was used in 49 patients, adjunctive cryoablation in 6, and cryoablation alone in 4. At 3.6 (1.6-5.7) years follow-up, 89% achieved clinical success with reduced antiarrhythmic drug use.

Conclusions: RV endocavitary arrhythmias typically occur in structurally normal hearts as focal PVCs. PVCs-triggering VF have shorter CIs and preferentially arise from the lateral MB. Ablation is effective in management.

Keywords: cardiomyopathy; catheter ablation; moderator band; premature ventricular contractions; right ventricular arrhythmias; ventricular fibrillation.

Graphical abstract

Central Illustration

Catheter Ablation of Right Ventricular Endocavitary Arrhythmias AAD = antiarrhythmic drug; LVEF = left ventricular ejection fraction; NICM = nonischemic cardiomyopathy; RF = radiofrequency; RV = right ventricular; other abbreviations as in Figures 1 and 2.

Figure 1

Example Tracings of Moderator Band Arrhythmias in our Study Population (A) Representative 12-lead ECGs of PVCs ablated from the lateral, body, and medial moderator band, (B) a PVC with a short coupling interval degenerating into polymorphic VT which was ablated at the lateral junction of the moderator band complex and (C) sustained symptomatic VT ablated from the body of the moderator band. ECG = electrocardiogram; PVC = premature ventricular contraction; VT = ventricular tachycardia.

Figure 2

Site of Ablation on the Moderator Band Complex Data presented as raw counts (n = 47 total observations) and group comparisons were made using Fisher exact test (P = 0.03). VF = ventricular fibrillation; other abbreviations as in Figure 1.

Figure 3

Changes in Premature Ventricular Contraction Burden and Left Ventricular Ejection Fraction (A) Premature ventricular contraction (PVC) burden in the 25 patients referred for PVC ablation decreased from 15% (IQR: 9%-22%) prior to the index ablation to 2% (IQR: 1%-3%) at the last clinical follow-up (P < 0.01); data displayed as median (IQR). (B) Left ventricular ejection fraction (LVEF) improved from 38% ± 6% to 55% ± 6% in the 7 patients with PVC-mediated cardiomyopathy after catheter ablation (P < 0.01); data displayed as mean ± SD.

Figure 4

Antiarrhythmic Therapy The distribution of antiarrhythmic therapy prior to index ablation and at the last clinical follow-up in patients referred for ablation of PVC-triggered VF (A) and VT (B). Abbreviations as in Figures 1 and 2.

Figure 5

Freedom From Right Ventricular Endocavitary Complex Arrhythmias Postablation (A) Cumulative freedom from right ventricular endocavitary complex arrhythmias following index ablation and (B) freedom from arrhythmias stratified by clinical presentation (P = 0.49). Abbreviations as in Figures 1 and 2.

Figure 6

Coupling Interval and QRS Duration of Premature Ventricular Contractions (A) Coupling interval and (B) QRS duration of premature ventricular contractions (PVCs) originating from the moderator band stratified by site of ablation. Data presented as median (IQR). Group comparisons were made using the Kruskal-Wallis test. MB = moderator band.

Figure 7

Example Case Example case of a 45-year-old gentleman with a history of an out-of-hospital cardiac arrest with documented VF who had recurrent appropriate ICD shocks (A). He had nonobstructive coronary artery disease with a structurally normal heart with focal nonspecific delayed gadolinium enhancement noted at the right ventricular insertion site and a variant of uncertain significance in alpha-protein kinase 3. He underwent ablation for PVC-triggered VF with earliest pre-QRS local ventricular electrogram (69 ms) (B) in the lateral aspect of the moderator band (C). Radiofrequency ablation followed by cryoablation was used with intracardiac echocardiography depicting the site of ablation (D). He was continued on flecainide 100 mg orally twice daily for 3 months postablation without clinical recurrence. ICD = implantable cardioverter-defibrillator; VF = ventricular fibrillation; other abbreviations as in Figures 1 and 6.