Pulsed Field Ablation for Pulmonary Vein Isolation in Atrial Fibrillation

TLDR

Catheter ablation with thermal energies causes indiscriminate tissue damage, whereas pulsed field ablation uses subsecond electric fields to electroporate cells, and cardiomyocytes have the lowest thresholds, allowing preferential myocardial ablation. The trials aimed to evaluate whether pulsed field ablation can achieve durable pulmonary vein isolation without collateral damage and to assess its safety and efficacy in paroxysmal atrial fibrillation. The study used proprietary bipolar pulsed field ablation waveforms—monophasic under general anesthesia with paralytics or biphasic under sedation—without esophageal protection, achieving acute isolation of all pulmonary veins in 81 patients within 3 minutes per patient and a mean procedure time of 92 minutes. With waveform refinement, 3‑month durability rose to 100 % and no major adverse events were observed over 120 days, while 12‑month freedom from arrhythmia was 87 % and the procedure demonstrated rapid isolation, durable results, and chronic safety. The trials are registered as IMPULSE (NCT03700385) and PEFCAT (NCT03714178).

Abstract

Catheter ablation of atrial fibrillation using thermal energies such as radiofrequency or cryothermy is associated with indiscriminate tissue destruction. During pulsed field ablation (PFA), subsecond electric fields create microscopic pores in cell membranes-a process called electroporation. Among cell types, cardiomyocytes have among the lowest thresholds to these fields, potentially permitting preferential myocardial ablation.The purpose of these 2 trials was to determine whether PFA allows durable pulmonary vein (PV) isolation without damage to collateral structures.Two trials were conducted to assess the safety and effectiveness of catheter-based PFA in paroxysmal atrial fibrillation. Ablation was performed using proprietary bipolar PFA waveforms: either monophasic with general anesthesia and paralytics to minimize muscle contraction, or biphasic with sedation because there was minimal muscular stimulation. No esophageal protection strategy was used. Invasive electrophysiological mapping was repeated after 3 months to assess the durability of PV isolation.In 81 patients, all PVs were acutely isolated by monophasic (n = 15) or biphasic (n = 66) PFA with ≤3 min elapsed delivery/patient, skin-to-skin procedure time of 92.2 ± 27.4 min, and fluoroscopy time of 13.1 ± 7.6 min. With successive waveform refinement, durability at 3 months improved from 18% to 100% of patients with all PVs isolated. Beyond 1 procedure-related pericardial tamponade, there were no additional primary adverse events over the 120-day median follow-up, including: stroke, phrenic nerve injury, PV stenosis, and esophageal injury. The 12-month Kaplan-Meier estimate of freedom from arrhythmia was 87.4 ± 5.6%.In first-in-human trials, PFA preferentially affected myocardial tissue, allowing facile ultra-rapid PV isolation with excellent durability and chronic safety. (IMPULSE: A Safety and Feasibility Study of the IOWA Approach Endocardial Ablation System to Treat Atrial Fibrillation; NCT03700385; and PEFCAT: A Safety and Feasibility Study of the FARAPULSE Endocardial Ablation System to Treat Paroxysmal Atrial Fibrillation; NCT03714178).