A case report of persistent phrenic nerve injury following pulsed field ablation using a pentaspline catheter

Background: Pulsed field ablation (PFA) is an emerging non-thermal ablation modality for atrial fibrillation (AF), characterized by its myocardial selectivity and reduced risk of collateral damage to extracardiac structures such as the oesophagus and phrenic nerve (PN). While transient phrenic nerve injury (PNI) has been reported, persistent diaphragmatic paralysis remains exceedingly rare. Case presentation: We report the case of a 49-year-old man with paroxysmal AF, refractory to medical therapy, who underwent pulmonary vein isolation using the FARAPULSE PFA system. The procedure was uneventful, and the patient was discharged the same day. However, he reported significant breathlessness on minimal exertion starting the day after the procedure. At his 6-week follow-up, physical examination revealed reduced air entry at the right lung base. A contrast-enhanced computed tomography chest confirmed an elevated right hemidiaphragm (9.0 cm posteriorly, 7.5 cm anteriorly), consistent with right PN palsy. The patient remained in sinus rhythm and asymptomatic from an arrhythmic standpoint, but continues to experience persistent dyspnoea. Discussion: To our knowledge, this represents one of the early cases of persistent PN palsy following PFA with the FARAPULSE system. Although PFA is designed to target cardiomyocytes while sparing adjacent tissues selectively, proximity to the right PN-particularly near the right superior pulmonary vein-may still pose a risk. This case highlights the importance of procedural vigilance, including meticulous catheter positioning and careful consideration of nerve proximity. It highlights that persistent PNI, while rare, remains a potential complication of PFA.