High incidence of phrenic nerve injury in patients undergoing pulsed field ablation for atrial fibrillation

BACKGROUND: Pulsed field ablation (PFA) is thought to reduce the risk of phrenic nerve injury (PNI) during atrial fibrillation (AF) ablation because of its myocardial selectivity. However, several reports suggest PNI still occurs. OBJECTIVE: This study aimed to evaluate the incidence and characteristics of PNI during PFA using sequential compound motor action potential (CMAP) monitoring and assess diaphragmatic function at discharge. METHODS: This prospective study included 64 consecutive patients undergoing PFA for AF. Right phrenic nerve function was monitored using CMAP during ablation. A baseline amplitude was measured before right pulmonary vein ablation, and subsequently monitored sequentially throughout the procedure. In case of intra-procedural PNI, all patients underwent a chest X-ray, and the last 25 also had a fluoroscopic loop the following day. RESULTS: PNI occurred in 26 patients (40.6%). Incomplete recovery was observed in 12 (18.8%) at the end of the procedure. Chest X-rays were normal in all cases. Among the last 25 patients, 12 experienced intra-procedural PNI and underwent fluoroscopic assessment at discharge, of whom 6 patients (50%) had persistent incomplete PNI. The overall incidence of PNI at discharge was 24% (6/25). Follow-up fluoroscopy confirmed recovery in 4 of 5 patients reassessed, while 1 showed persistent dysfunction at 3 months. CONCLUSION: PNI is a frequent complication of PFA. Incomplete paralysis is commonly observed at the end of the procedure. Fluoroscopy enables diagnosis of incomplete PNI at discharge, which remains a frequent finding. One patient showed persistent dysfunction at 3 months.