Acute Efficacy of Pulsed‐Field Ablation of the Mitral Isthmus Using a Pentaspline Catheter and Two Different Ablation Settings

Introduction There is limited data regarding the use of pulsed‐field ablation (PFA) for mitral isthmus (MI) ablation in patients with non‐paroxysmal atrial fibrillation (AF). Our aim was to assess the acute efficacy of MI ablation using a pentaspline PFA catheter with two different ablation settings. Methods Patients with AF undergoing ablation were consecutively enrolled. All patients underwent pulmonary vein isolation and left atrial posterior wall ablation. MI ablation was performed in up to 4 series (9 PFA applications each) in Cohort A, or in up to 3 series (20 PFA applications each) in Cohort B. Each series was followed by a 20‐min observation period to verify the durability of the MI block. The primary endpoints were a first‐pass MI block and a final MI block after all ablation series. Results Between September 2024 and June 2025, 70 patients were enrolled: 30 in Cohort A and 40 in Cohort B. A first‐pass MI block was achieved in 10 (33.3%) patients in Cohort A and 28 (70%) patients in Cohort B ( p = 0.003). A final MI block was present in 27 (90%) and 35 (87.5%) patients in Cohort A and B, respectively ( p = 1.00). The median reconduction time was 6 min (IQR 2.8–9.4) in Cohort A and 5 min (IQR 2.6–8.7) in Cohort B. No major complications occurred. Conclusion Using series of 20 PFA applications increased the success rate of a first‐pass MI block to 70%. An observation period is recommended to verify the durability of MI block in PFA. Clinical Trial Registration: NCT06803238.