LAUSR

BACKGROUND Catheter ablation of atrial fibrillation using thermal energies such as radiofrequency or cryothermy is associated with indiscriminate tissue destruction. During pulsed field ablation (PFA), sub-second 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. OBJECTIVES To determine whether PFA allows durable pulmonary vein (PV) isolation without damage to collateral structures. METHODS We conducted two trials 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 since there was minimal muscular stimulation. No esophageal protection strategy was employed. Invasive electrophysiological mapping was repeated after three months to assess durability of PV isolation. RESULTS 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 one procedure-related pericardial tamponade, there were no additional primary adverse events over 120 days 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%. CONCLUSIONS In first-in-human trials, pulsed field ablation preferentially affected myocardial tissue, allowing facile ultra-rapid PV isolation with excellent durability and chronic safety.