BACKGROUND: Pulsed field ablation (PFA) is an emerging, nonthermal ablation technology with promising safety characteristics due to its cardiomyocyte selectivity. While several studies evaluated the use of multispline PFA catheters for pulmonary vein isolation (PVI), limited data exists on the utilization of focal PFA for repeat ablation of atrial fibrillation (AF). The purpose of this study was to prospectively investigate the feasibility, safety and lesion characteristics of point-by-point PFA-based Re-PVI and left atrial anterior line (AL) ablation using a commercially available, contact force-sensing, solid-tip focal ablation catheter in conjunction with a novel PFA generator (CENTAURI™, Galvanize Therapeutics - Electrophysiology).

METHODS: Consecutive patients with paroxysmal or persistent AF undergoing repeat ablation of AF were prospectively enrolled. High-resolution 3D electroanatomical mapping of the left atrium (LA) was obtained before and after ablation. Point-by-point PFA was performed with use of the CENTAURI system and a regular THERMOCOOL SMARTTOUCH (Biosense Webster) ablation catheter.  Re-isolation of the pulmonary veins (PV) was performed in patients with reconnected PV. In patients with significant substrate along the left atrial anterior wall and/or durable PVI, an AL connecting the anterolateral mitral annulus with the right superior PV was ablated aiming at bidirectional block. 

RESULTS: 25 consecutive patients (50% female, 67 ± 10 years, 67% persistent AF) were enrolled. Re-isolation of the PVs was achieved in 25/25 PVs (100%; 12/12 (100%) patients). A total of 19 AL were deployed. Bidirectional block of the AL was achieved in 16/19 (84%) patients with a mean ablation time 27 ± 11 minutes and first-pass bidirectional block in 13/19 (68%) patients. For AL ablation 37 ± 12 focal PFA applications with a mean contact force of 23 ± 6 g and a mean impedance of 84 ± 12 Ω were delivered. In 8/19 (42%) patients there was an acute reconnection of the AL during the predefined waiting period of 30 minutes. Of those 5/8 (63%) were successfully re-blocked (including a waiting period of another 30 minutes). In 3/19 (16%) patients no sustained AL block was achievable. Mean procedure, LA dwell, and fluoroscopy times were 99 ± 16 min, 85 ± 17 min, and 10 ± 3 min, respectively. One pericardial tamponade requiring pericardiocentesis occurred before PFA delivery. No further minor or major complications occurred. 

CONCLUSION: Point-by-point PFA-based ablation of the AL was feasible, acutely effective, and safe. Further studies are needed to evaluate the comparative and long-term durability of focal PFA.