Ablation procedure
The ablation procedures were started in the morning. The details of the double Lasso catheter-guided extensive encircling pulmonary vein antrum isolation performed in this study have been described previously [17]. In brief, 2 decapolar circular catheters were positioned within the ipsilateral superior and inferior pulmonary veins. Circumferential ablation lines were created around the left- and right-sided ipsilateral pulmonary veins with the use of a 3.5 mm-tip irrigated catheter (Thermocool SmartTouch®, Biosense Webster, Diamond Bar, CA, USA). Radiofrequency energy was delivered with a maximum power of 30 Watt. Real-time contact force data were used to guide the ablation procedures, with a target force of 10-15 g. The goal of the procedure was to achieve both pulmonary vein entrance and exit block [1].