Direct epicardial validation of posterior wall isolation in persistent atrial fibrillation: pulsed field versus radiofrequency ablation

Abstract

Abstract Background Lesion transmurality is an important determinant of durable effectiveness of catheter ablation (CA) for atrial fibrillation (AF). The impact of different energy sources on the achievement of transmural left atrial (LA) ablation has not been explored so far. Purpose We sought to compare the transmurality associated with pulsed field ablation (PFA) and radiofrequency (RF) ablation of LA posterior wall (PW) among patients with persistent AF. Methods Eight patients (mean age, 70±7 years; 88% male) undergoing CA for persistent AF with PW ablation and adjunctive high-density epicardial mapping were included in a multicenter international registry. In four patients, PW ablation was performed using PFA, while in the remaining four, RF energy was used with high/very-high-power short-duration settings. The primary study outcome was transmural PW isolation (PWI) with endocardial-only ablation. Results A trend towards shorter times required to complete endocardial PW ablation was observed with PFA compared to RF (9±1 vs 11±2min, p=0.065). At endocardial mapping, apparent PWI was observed in all cases. However, transmural PWI after endocardial-only ablation was demonstrated in each patient in the PFA group, but only in one RF case, in whom 50 Watt/≥10 sec settings were used (100% vs 25%, p=0.143). Interestingly, in three patients in the RF group, endocardial ablation resulted in conversion of AF into atypical flutter, which could be successfully terminated by epicardial ablation. Conclusions We observed a trend towards greater transmurality with PFA compared to high/very-high power RF ablation in the region of septopulmonary bundle. This observation may have potential implications on clinical outcomes after endocardial AF CA.