Inclusion Criteria:  Aged 18 to 80 years old; Persistent AF with severe atrial fibrosis; Nonresponse or intolerance to ≥1 antiarrhythmic drug.  Exclusion Criteria:  With uncontrolled congestive heart failure; Having significant valvular disease; With myocardial infarction or stroke within 6 months of screening; With Significant congenital heart disease; Ejection fraction was <40% measured by echocardiography; Allergic to contrast media; Contraindication to anticoagulation medications; Severe pulmonary disease e.g. restrictive pulmonary disease, chronic obstructive disease (COPD); Left atrial (LA) thrombus; Having any contraindication to right or left sided heart catheterization; 11. Previous atrial fibrillation ablation;  12. Presence of an implanted cardioverter-defibrillator; 13. Previous history of cardiac surgery; 14. Poor general health; 15. Life expectancy less than 6 months.