Electrophysiological evaluation of incidental superior vena cava isolation following pulsed field ablation: a case report.

Background: Pulsed field ablation (PFA) is increasingly adopted for atrial fibrillation (AF) due to its efficacy and lower risk of complications. However, uniform transmural energy delivery may induce excessive tissue modification and unintended effects on adjacent structures. Pulsed field ablation of the right superior pulmonary vein (RSPV) can result in conduction delay within the superior vena cava (SVC), but its electrophysiological properties remain poorly characterized. Case summary: An 81-year-old man with ischaemic cardiomyopathy, chronic heart failure, and paroxysmal AF underwent PFA for pulmonary vein isolation and posterior wall isolation. Pre-ablation mapping revealed myocardial sleeves within the SVC. Post-PFA mapping demonstrated complete SVC isolation. However, conduction recurred following adenosine triphosphate administration, and ectopic activity originated from the SVC. Circumferential radiofrequency ablation was subsequently performed, achieving durable SVC isolation. Discussion: This case demonstrates that PFA of the RSPV can lead to incidental SVC isolation. The presence of adenosine-induced dormant conduction highlights the potential for late reconnection, while the observation of ectopic activity supports the need for adjunctive ablation. Pulsed field ablation may unintentionally affect adjacent myocardial tissue, including the SVC and components of the cardiac conduction system. Therefore, careful electrophysiological assessment and monitoring of conduction recovery are essential to prevent arrhythmogenic triggers and to ensure durable isolation.