1. Purpose of the study

1) To compare clinical outcome, procedure time, complication rate of patients who were changed to paroxysmal atrial fibrillation from persistent atrial fibrillation between ablation with conventional pulmonary vein isolation and ablation with conventional pulmonary vein isolation with conventional linear ablation.

2. Scientific evidence of the study

1. In atrial fibrillation patients, the maintenance of normal sinus rhythm showed significant reduction of mortality.
2. drug therapy with anti-arrhythmic drug showed many complications and side effect, thus non-drug therapy such as catheter ablation is developed.
3. catheter ablation has been performed for 10years world-wide, and showed superior treatment outcome compared with drug therapy.
4. However, there are no consensus for proper ablation strategy in patients who were changed to paroxysmal atrial fibrillation from persistent atrial fibrillation .
5. additional ablation make extent of myocardial injury and paradoxically increase recurrence rate, thus still controversial.
6. Therefore, we will compare conventional pulmonary vein isolation with additional conventional linear ablation.

3. Methods

1. Treatment of All patients with atrial fibrillation is performed according to the standard treatment guideline of atrial fibrillation.
2. there is no additional blood sampling, imaging study, or any other invasive procedure according to the inclusion of the study.

4. study contents

1) to evaluate superior ablation strategy in patients who were changed to paroxysmal atrial fibrillation from persistent atrial fibrillation

• compare conventional pulmonary vein isolation with additional liner ablation, both strategies are conventional ablation strategies being performed world-wide.

Inclusion Criteria:

1) patients who undergoing catheter ablation of atrial fibrillation due to symptomatic, drug refractory atrial fibrillation

Exclusion Criteria:

1. patients who do not agree with study inclusion
2. permanent AF refractory to electrical cardioversion
3. AF with valvular disease ≥ grade 2
4. Patients with left atrial diameter greater than 60mm
5. patients with age less than 19