This is an open label, randomized parallel control clinical trial, to compare extra-PV extensive ablation with in-situ ablation as two strategies for the treatment of PerAF to identify the mechanisms of PerAF recurrence.

This is an open label, randomized parallel control clinical trial. Patients with recurrent persistent atrial fibrillation are 1:1 randomized into EXT group(Extra-PV extensive ablation) and IN-SITU group(Repeat same PVI and linear ablation as the first procedure). Postoperative recurrence rate and other indicators are analyzed to compare extra-PV extensive ablation with in-situ ablation as two strategies for the treatment of PerAF to identify the mechanisms of PerAF recurrence.

Inclusion Criteria:

1. Age 18 years or older; 2) Diagnosed as recurrent PerAF according to the latest clinical guidelines; 3) Ineffective or intolerable to ≥1 anti-arrhythmia drug treatment; 4) the first ablation procedure was PVI and linear ablation; 5) consented to receive radiofrequency catheter ablation.

Exclusion Criteria:

• 1) Recurrent atrial flutter/atrial tachycardia; 2) The first ablation procedure included extra-PV substrate ablation; 3) The first low voltage area>30%; 4) Serious complications during the first procedure; 5) The first ablation was paroxysmal atrial fibrillation. 6) Uncontrolled congestive heart failure; 7) History of severe valve disease and/or prosthetic valve replacement; 8) Left atrial thrombus confirmed by preoperative esophageal ultrasound; 9) Severe congenital heart disease; 10) Severe lung disease; 11) Left atrial diameter ≥60mm; 12) Contraindications for cardiac catheterization; 13) Myocardial infarction or stroke within 6 months; 14) Contrast agent allergy; 15) The use of anticoagulant drugs is contraindicated; 16) Have performed any cardiac surgery within 2 months;17) life expectancy is less than one year, including factors such as physical inability to tolerate ablation or unstable disease conditions.