Management before the catheter ablation
A 12-lead electrocardiogram (ECG), chest X-ray, and echocardiogram were examined within 3 months before the catheter ablation. A transthoracic echocardiogram was performed to evaluate the left atrial diameter and left ventricular ejection fraction (LVEF). All patients underwent a 64-slice multi-detector row computed tomography (MDCT) within 1 week before the catheter ablation to obtain the configuration of the left atrial cavity and rule out any thrombi in the left atrium (LA) and left atrial appendage. A 60‐100 ml bolus of iodinated intravenous contrast was administered at a rate of 2.5‐5 ml/s, followed by a saline flush of 20‐30 ml. The slice data of the MDCT image was reconstructed into a 3-dimensional volume rendering using computer software (ZAIO station2, ZAIOSOFT, Tokyo, Japan). The 3-dimensional image clarified the anatomy of the LA and PVs: left superior pulmonary vein (LSPV), left inferior pulmonary vein (LIPV), right inferior pulmonary vein (RSPV) and right inferior pulmonary vein (RIPV). An LCPV is generally defined as a common trunk length of 5 mm or more, short common trunk length of 5-15mm, and long common trunk length of more than 15mm6,7). In this study, an LCPV was defined as a PV with an entire length between the PV ostium and PV bifurcation of longer than 15mm based on the MDCT image. All patients received anticoagulation therapy for at least 3 weeks before the ablation procedure. All antiarrhythmic drugs were discontinued for more than 5 half-lives before the ablation procedure, and amiodarone was not administered in any of the study patients.