Conduction recovery after electrical isolation of superior vena cava--prevalence and electrophysiological properties

Superior vena cava (SVC) is an infrequent yet an important source of atrial fibrillation (AF). The data on SVC reconnection are limited.

Following pulmonary vein (PV) antrum isolation for AF, SVC isolation was systemically performed under angiographic and mapping guidance using 4-mm non-irrigated tip catheter. SVC reconnection could be evaluated in 76 consecutive patients (65 ± 9 years, 59 male) who underwent repeat AF ablation after 16 ± 16 months. SVC was isolated at the 1(st), 2(nd), 3(rd) and 4(th) AF ablation procedure in 63, 7, 5 and 1 patient by 7.3 ± 3.1 radiofrequency applications. SVC reconnection was observed in 56 patients (74%). In the majority, the conduction gap was located at the anterolateral SVC-right atrium (RA) junction. After re-isolation of SVC, 2/7 patients (29%) had reconnection at the following procedure. Among 63 patients who underwent PV and SVC isolation at the initial procedure, the prevalence of reconnection for PV and that for SVC were similar (53/63, 84% vs. 46/63, 73%; P=0.129). Dissociated activity, however, was more frequently observed in the PVs than in the SVC (47/63, 73% vs. 10/63, 16%; P<0.0001). During the procedure, AF initiation from a thoracic vein was identified in 19/63 patients (30%).

SVC reconnection is common after 1 or more previous isolation procedures undertaken for AF ablation. Its prevalence is similar to that of PV reconnection. The location of the conduction gap varies widely but is most frequently found at the anterolateral SVC-RA junction.