Superior vena cava as initiator of atrial fibrillation: factors related to its arrhythmogenicity

Abstract

Background: The superior vena cava (SVC) is an important focus of atrial fibrillation (AF) for which SVC isolation is effective. However, SVC isolation may cause serious complications, and indications for SVC isolation combined with pulmonary vein (PV) isolation are unclear.

Objective: The purpose of this study was to identify structural and electrophysiologic differences that might exist between the SVC of patients with and those without SVC triggering of AF.

Methods: This study included paroxysmal (n = 46) and persistent (n = 14) AF patients without structural heart disease who underwent circumferential antral PV isolation. Patients with AF of SVC origin were assigned to the SVC group (n = 12); the remaining patients were assigned to the control group (n = 48). The area where SVC potentials were recorded was defined as the SVC sleeve. The length of the SVC sleeve and the maximum amplitude of the SVC potential were measured.

Results: SVC group patients had a longer SVC sleeve (34.7 +/- 4.4 mm vs 16.5 +/- 11.4 mm, P <.0001) than did control group patients. Maximum amplitude of the SVC potential was greater in SVC group patients than in control group patients (1.50 +/- 0.43 mV vs 0.98 +/- 0.60 mV, P = .03). SVC sleeve length >30 mm and maximum amplitude of SVC potential >1.0 mV strongly predicted an SVC focus of AF (100% sensitivity, 94% specificity). Fifty of 60 patients became AF-free without antiarrhythmic drugs after undergoing circumferential antral PV isolation and/or SVC isolation.

Conclusion: The results of this study suggest that in patients with long SVC sleeve (>30 mm) and large SVC potential (>1.0 mV), arrhythmogenic triggers of AF reside in the SVC.