Mapping and Ablation of Intramural Ventricular Arrhythmias: A Stepwise Approach Focused on the Site of Origin

Abstract

Objectives: This study sought to establish a mapping and ablation strategy to target intramural ventricular arrhythmias (VAs) by identifying the precise arrhythmia site of origin (SOO).

Background: Radiofrequency ablation of intramural VAs is challenging because the arrhythmia origin is difficult to localize.

Methods: In 83 consecutive patients with intramural VAs, a stepwise mapping approach was performed: ablation targeted directly the SOO when possible followed by the closest adjacent anatomical structure when necessary. If the SOO could not be identified, the earliest endocardial breakout sites were ablated. Safety and procedural outcomes between patients in whom the SOO could and could not be identified were compared.

Results: The SOO was identified in 19 of 83 (23%) patients, and radiofrequency ablation was effective in eliminating VAs in all 19 (100%) patients by ablation at the SOO alone (n = 3), at the SOO and an anatomically adjacent area (n = 7), or at an anatomically adjacent area alone (n = 9). Breakout site mapping and ablation in the remaining 64 patients in whom the SOO was not identified was effective in 43 of 64 patients, which was significantly less than in patients in whom the SOO was identified (67% vs. 100%; p < 0.05).

Conclusions: Identification of the SOO was associated with a successful ablation procedure by either targeting the SOO directly or targeting an adjacent anatomical structure. Ablation at the breakout sites of intramural VAs has a lower efficacy than when the SOO can be directly targeted.

Keywords: PVCs; ablation; intramural; mapping; ventricular arrhythmia.