Clinical Impact of Adenosine Triphosphate Injection on Arrhythmogenic Superior Vena Cava in the Context of Atrial Fibrillation Ablation

Background Superior vena cava (SVC) is an infrequent yet an important source of atrial fibrillation. The clinical impact of ATP injection on arrhythmogenic SVC has not been evaluated. Methods and Results A total of 43 patients (59 +/- 11 years; men, 32) who underwent ATP test for arrhythmogenic SVC after the electric isolation at either initial procedure or repeat procedure were included. Pulmonary vein antrum isolation was performed at index procedure in all patients. SVC was isolated after identifying the arrhythmogenicity at index and repeat atrial fibrillation ablation procedure in 34 (79.1%) and 9 (20.9%) patients, respectively. Atrial fibrillation originated from the SVC spontaneously and under isoproterenol infusion in 30 (75.0%) patients, and immediately after ATP injection in 10 (25.0%) patients. Tachycardia persistently confined to SVC was recorded after electric isolation in 13 (30.2%) patients. SVC reconnection was provoked by ATP test in 7 of 36 (19.4%) patients at acute phase. At median 4.0 (2.25-7.5) months after SVC isolation, reconnection was observed in 12 of 15 (80.0%) patients at repeat procedure. Among 12 patients with reconnection at baseline, SVC reconnection was provoked by ATP test after reisolation in 1 (8.3%) patient. Among 3 patients without SVC reconnection at baseline, reconnection was provoked by ATP test at chronic phase in 1 patient. Conclusions Dormant conduction between an arrhythmogenic SVC and the right atrium can be exposed by ATP administration both immediately and late after isolation, potentially facilitating detection and ablation for isolation.