Factors predicting an arrhythmogenic superior vena cava in atrial fibrillation ablation: Insight into the mechanism

BACKGROUND The superior vena cava (SVC) is an infrequent but important source of atrial fibrillation (AF), but is not always easy to identify. OBJECTIVE This study aimed to identify predictors of an arrhythmogenic SVC (a-SVC) in patients undergoing AF ablation. METHODS Eight hundred thirty-six consecutive patients undergoing AF ablation were analyzed. All patients underwent pulmonary vein antrum isolation during the index procedure. An a-SVC, defined as SVC-triggered AF and an SVC associated with the maintenance of AF, was evaluated by mapping catheters throughout the procedure. RESULTS An a-SVC was identified in 44 patients (5.3%) during a total of 1063 procedures. Patients with an a-SVC were younger, less obese, and had a smaller Left atrial (LA) size and more paroxysmal AF than those without an a-SVC. The presence of structural heart disease and hypertension was lower, and the coexistence of spontaneous common atrial flutter (Aft) before or during the index procedure was higher in those with an a-SVC than in those without. A multiple logistic regression analysis revealed that the LA size (odds ratio 0.93; 95% confidence interval 0.88-0.99; P = .038) and coexistence of spontaneous common AFL (odds ratio 2.01; 95% confidence interval 1.00-4.02; P = .048) were independent predictors identifying an a-SVC. Although 19 patients (43.2%) required repeat procedures, 39 (88.6/a) were free from any atrial tachyarrhythmias without antiarrhythmic drugs at a median of 16.5 months (25th-75th percentiles 9.0-27.0 months) after a mean of 1.5 +/- 0.7 procedures. CONCLUSION A smaller LA size and coexistence of spontaneous common AFL were independent predictors of an a-SVC in the context of AF ablation.