Efficacy and Safety of Right Neck Phrenic Nerve Pacing in Patients Undergoing Cryoablation for Atrial Fibrillation

BACKGROUND Balloon-based ablation (BBA) is a useful treatment strategy for atrial fibrillation (AF) despite the current trend of decreasing BBA volume due to pulsed-field ablation. However, during BBA for AF of the right-sided (RS) pulmonary veins (PVs) (RS-PVs), constant phrenic nerve (PN) pacing from the superior vena cava (SVC) is required to prevent right PN injury. The PN courses anterior to the scalenus anterior muscle and posterior to the sternocleidomastoid muscle in the neck via a branch of the C3-5 roots. This study determined the efficacy and safety of right PN pacing from the neck during cryoablation of RS-PVs. METHODS This study was a within-patient crossover comparison, and 104 patients underwent PN pacing from both the neck and SVC. In one group (n = 52), right inferior (RI) PV ablation was performed during pacing from the SVC, and right superior (RS) PV ablation was performed during pacing from the neck. The other group (n = 52) underwent RIPV ablation during pacing from the neck and RSPV ablation during pacing from the SVC. RESULTS In 96 (92%) of the 104 patients, the PN was effectively and safely paced from the neck during cryoablation of RSPVs without any complications, including permanent PN, accessory nerve, supraclavicular nerve, and/or brachial plexus injury, except in two patients with transient PN injury. Neck obesity (neck-to-height ratio > 0.252) and lower compound motor action potentials were independent predictors of unsuccessful neck pacing. CONCLUSIONS For patients with AF, PN pacing from the right neck during cryoablation of right-sided PVs may be a feasible, safe, and optional treatment strategy for selected patients without neck obesity. CLINICAL TRIAL REGISTRATION This study was registered in the University Hospital Medical Information Network-Clinical Trial Registry of Japan (UMIN000047242). https://www.umin.ac.jp/ctr/index-j.htm.