Follow-up
Each enrolled patient was followed up at 3, 6 and then every 6 months subsequently by trained staff, either through a telephone interview or at an outpatient clinic. During each follow-up, information related to clinical results and medical treatment was collected. In addition, 24-hour Holter monitoring was performed, and 12-lead electrocardiograms were recorded at every visit. Additional electrocardiograms were performed if arrhythmic symptoms occurred. No atrial tachyarrhythmia lasting at least 30 seconds beyond the 3-month blanking period was defined as successful ablation.