The purpose of this study is to compare the clinical outcomes depending on catheter ablation strategy for persistent atrial fibrillation. After randomization, investigators will conduct circumferential pulmonary vein isolation alone in a group, and additional posterior box isolation and anterior linear ablation in the other group. Investigators will compare clinical recurrence rate, complication rate, and procedure time, etc.

Inclusion Criteria:

• Patients with persistent Atrial fibrillation (20~80 years)
• LA diameter <55mm
• patients possible to anticoagulation and anti arrhythmic drug

Exclusion Criteria:

• Structural cardiac disease
• Contraindication to brain perfusion CT
• Catheter ablation history for AF,
• Cardiac surgery for AF
• active internal bleeding
• Impossible to anticoagulation or antiarrhythmic drug
• valvular AF (MA> GII, Mechanical valve, Mitral valve replacement)
• Patients with severe medical disease
• Expected survival < 1year
• Severe alcoholics, drug addiction