The electrophysiological mechanisms of atrial fibrillation remain disagreements. The goal of this clinical trail is to propose a new electrophysiological mechanism hypothesis of atrial fibrillation（AF）,meanwhile, the investigators sought to test the hypothesis that the superposition electrograms (SPEs) recorded during atrial fibrillation could be used as target sites for catheter ablation of atrial fibrillation.

Catheter ablation for atrial fibrillation is a promising therapy, whose success is limited in part by uncertainty in the electrophysiological mechanisms of AF. The investigators recruited 100 subjects including paroxysmal(40%) and persistent (60%) AF. Cases were prospectively treated, in a 2-arm 1:1 design, by ablation SPEs followed by pulmonary vein isolation(PVI) ablation (n=50), or pulmonary vein isolation alone (n =50).

All procedures are guided by CARTO (Biosense Webster) electroanatomic mapping system and ablation is performed using open irrigated catheters with contact force (CF) sensing (Thermocool SmartTouch, Biosense Webster). Study Group underwent electroanatomic mapping during AF. Using CARTO to identify areas associated with SPEs. Radiofrequency ablation of the area with SPEs was performed, aiming to eliminate SPEs and convert to sinus rhythm or atrial tachycardia.

Inclusion Criteria:

• Patients undergoing a first-time ablation procedure for AF
• Paroxysmal AF will be defined as a sustained episode lasting > 7 days; Persistent AF will be defined as a sustained episode lasting > 7 days and less than 1 years; Long-lasting persistent AF will be more than 1 year and less than 5 years.
• Patients must be willing and able to comply with all peri-ablation and follow-up requirements.
• Patients with atrial fibrillation will to accept the procedure of ablation.
• Patients signed the written informed consent for the study.
• Patients can endure the required follow up.

Exclusion Criteria:

• Patients with contraindications to systemic anticoagulation with heparin or a direct thrombin inhibitor.
• Patients with thromboembolus in left atrial appendage.
• Patients with left atrial size ≥ 55 mm (2D echocardiography, parasternal long-axis view).
• Patients allergic for contrast or iodine.
• Patients with the serum creatinine（SCr） >3.5mg/dl
• Patients with life expectancy < 12 months
• Patients who are in the period of pregnant