Feasibility and Safety of Pulsed Field Ablation for Coronary Sinus and Left Atrial Appendage Isolation and Mitral Isthmus Ablation: Acute and Chronic Findings

BACKGROUND: The safety and efficacy of pulsed field ablation for pulmonary vein and posterior wall isolation in atrial fibrillation ablation are well established; however, evidence regarding its use in extra-pulmonary vein areas remains limited. The aim of this study was to assess the feasibility and durability of pulsed field ablation for coronary sinus (CS) and left atrial appendage (LAA) isolation and mitral isthmus (MI) ablation. METHODS: We analyzed data from consecutive patients who underwent repeat atrial fibrillation ablation with pulsed field ablation between February and October 2024. MI ablation, CS isolation, and LAA isolation were attempted in all patients using the Farapulse (Boston Scientific) ablation system. Acute isolation was assessed after a 20-minute waiting period and an adenosine challenge, while chronic durability was evaluated during a repeat procedure for LAA closure at 3 months. RESULTS: A total of 236 patients (145, 61.4% male) were included in our analysis. Acute CS isolation was achieved in 147 (62.2%) patients for the CS and in all patients for the LAA. Acute MI block was obtained in all patients. After a 20-minute waiting time, the adenosine challenge revealed dormant conduction in 52 (26.4%) cases for the CS, in 4 (1.7%) for the LAA, and MI block regression in 35 (14.8%). All patients underwent remapping at the time of left atrial appendage occlusion, which showed CS and LAA isolation in only 3 (1.3%) and 10 (4.6%) patients, respectively, and MI block in 13 (5.5%) cases. CONCLUSIONS: Pulsed field ablation is a feasible and acutely effective method for CS and LAA isolation and MI block; however, lesion durability remains a significant limitation.