Atrial fibrillation, which can result in stroke and thromboembolism in an approximately 5-fold increased risk, has been a great burden to health care system with the aging of population. Catheter ablation is the most promising treatment of atrial fibrillation. However, the recurrence rates of AF after catheter ablation are high, ranging from 20%-60%. Therefore, non-invasive predictors for AF recurrence after catheter ablation is necessary to select the optimal patients for this procedure.