The purpose of this study is to compare the efficacy of catheter ablation for atrial fibrillation between contact force-guided and impedance-guided annotation using automated annotation system (Visitag™). Patients who receive atrial fibrillation ablation are randomly assigned in the same number to two groups with impedance guided ablation and contact force guided ablation using contact force sensing catheter (THERMOCOOL® SMARTTOUCH™ catheter, Biosense Webster, Inc., Diamond Bar, CA).

During atrial fibrillation ablation, the location where ablation is conducted is displayed through annotation tags using 3D system to recognize energy delivery is done at the area. However this annotation method was unable to identify how effectively the ablation is done. To remedy this disadvantage, automated annotation system (VisiTag™ module, Biosense Webster, Inc., Diamond Bar, CA) was recently developed to make an automatic annotation when all pre-defined criteria are satisfied. But study on the clinical effects of this system is insufficient.

The purpose of this study is to compare the efficacy of catheter ablation for atrial fibrillation between contact force-guided and impedance-guided annotation using automated annotation system.

Inclusion Criteria:

• Patients with non-valvular atrial fibrillation
• Patients having atrial fibrillation even after receiving continued treatment with at least 1 antiarrhythmic drug for more than 6 weeks
• Patients with tachycardia-bradycardia syndrome associated with atrial fibrillation.
• Patients who can understand the information sheet and consent form on the need and procedure of catheter ablation and submitted them
• Patients who are available of follow-up at least for more than three months after catheter ablation

Exclusion Criteria:

• Patients unsuitable for catheter ablation because the size of left atrium is over 5.5cm
• Patients unsuitable for catheter ablation due to previous history of pulmonary surgery or structural heat disease.
• Patients who cannot receive standard treatments such as anticoagulation therapy which need to be continuously performed prior to radiofrequency catheter ablation
• Patients in the subject group vulnerable to clinical study
• Patients who had undergone a prior catheter ablation for atrial fibrillation