The purpose of this study is to evaluate the efficacy of high density voltage and fractionation map guided ablation compared to anatomy-based circumferential pulmonary vein Isolation in patients with atrial fibrillation

In this study, a test group includes those who undergoing atrial fibrillation(AF) ablation guided by high density voltage and fractionation map. A control group will be chosen from database of patients who underwent AF ablation between 2018-2019. A control group includes the same number of consecutive patients who underwent anatomy-based circumferential pulmonary vein (PV) isolation.

Inclusion Criteria:

• 1. Age over 20 years old and under 80 years old 2. Patients with non-valvular atrial fibrillation 3. Patients having AF even after receiving continued treatment with at least 1 antiarrhythmic drug for more than 6 weeks 4. Patients who can understand the information sheet and consent form on the need and procedure of catheter ablation and submitted them 5. Patients who are available of follow-up at least for more than three months after catheter ablation

Exclusion Criteria:

1. Patients unsuitable for catheter ablation because the size of left atrium is over 6.0 cm
2. Patients unsuitable for catheter ablation due to previous history of pulmonary surgery or structural heat disease.
3. Patients who cannot receive standard treatments such as anticoagulation therapy which need to be continuously performed prior to radiofrequency catheter ablation
4. Patients in the subject group vulnerable to clinical study
5. Patients who had undergone a prior catheter ablation for atrial fibrillation