Relationship between Effective Refractory Period and Inducibility of Atrial Fibrillation from the Superior Vena Cava after Pulmonary Vein Isolation

Abstract

In terms of the pulmonary vein (PV), atrial fibrillation (AF) patients have a shorter effective refractory period (ERP) than those without AF and a large dispersion of the ERP. Although the frequency of AF from the superior vena cava (SVC) was the highest among non-PV foci, the characteristics of the ERP in the SVC (SVC-ERP) were unclear. The purpose of this study was to elucidate the relationship between SVC-ERP and the inducibility of AF after PV isolation (PVI). Consecutive 28 patients who underwent PVI were included. After successful PVI, the SVC-ERP was measured at three positions in SVC. Rapid electrical stimuli were delivered at the shortest SVC-ERP to induce AF. Patients in whom AF was induced were assigned to the SVC-induced group (SIG), and the remaining patients were the non-SVC-induced group (non-SIG). The size of the SVC sleeve was evaluated via three-dimensional electroanatomic mapping. The SIG had a significantly shorter average SVC-ERP (236.0 ± 25.2 versus 294.8 ± 36.8 ms, P < 0.001), whereas SVC-ERP dispersion was not significantly different (30.0 ± 25.4 versus 33.3 ± 20.1 ms, P = 0.56). Although the longer SVC diameter was significantly longer in the SIG (27.4 ± 4.3 versus 22.9 ± 4.6 mm, P = 0.03), the SVC-ERP was significantly associated with pacing inducibility of AF after adjustment for the longer SVC diameter (odds ratio: 0.96 [1 ms increments], P = 0.01). The SIG had a shorter SVC-ERP, whereas the dispersion was not significantly different between the two groups. The SVC-ERP can be one of the mechanisms of arrhythmogenicity for AF originating from the SVC.