The purpose of the study is to investigate whether or not there are the differences in acute procedure and long-term clinical outcome of radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF) using the 3D map constructed by the integration of CT(or MRI) with the fast anatomical mapping (FAM) versus using the 3D map constructed by FAM only.

In a recent study, ablation therapy of AF was superior to antiarrhythmic drug therapy alone in preventing atrial arrhythmia recurrences in patients with paroxysmal or persistent AF. Various techniques have been proposed and are currently under investigation in various electrophysiology laboratories, with increasing knowledge of the pathophysiology of human AF and critical assessment of clinical outcome after the procedure. The factors related with the technical success involves appropriate contact force between catheter tip and target tissue for the complete electrical blockade and transmural ablation scar formation through continuous and sufficient energy transfer.

For improving contact and energy transfer, it is required to accurately visualize the 3D anatomy of the left atrium in order to reduce fluoroscopic exposure during the procedure. For the purpose, electro-anatomic mapping systems (EAM) are commonly being used to reconstruct a virtual 3D chamber anatomy through the acquisition of a limited number of anatomical surface location points derived from the position of the catheter tip and an extrapolation of the chamber surface in between these acquired anatomical points.

Previously, a more detailed appreciation of the complex left atrium (LA) anatomy can be obtained with 3D-anatomical chamber reconstructions derived from the computed tomography (CT) or magnetic resonance imaging(MRI). Integration of EAM with CT (or MRI) was generally regarded as a more accurate method. However, the method needs to be improved since it sometimes generates significant error during the integration process. Recently, volume-rendered 3D imaging can be created more accurately and easily through fast anatomical mapping (FAM) using multi-polar catheter. Furthermore, 3D anatomy obtained by FAM might provide more sophisticated information than that obtained from CT or MRI images since it reflects the real-time physiology and shape of the heart during the ablation procedure.

However, there have been no prospective studies investigating that 3D anatomy obtained through which method can help to improve acute or long-term procedural outcome of the ablation procedure as well as reduce procedure-related adverse effects or complications.

The purpose of the study is to investigate the differences between the 3D map constructed by the integration of the FAM with CT or MRI (FAM-CT 3D map) and that by FAM (FAM 3D map) alone with respect to following aspects:

1. the contact force between the electrode and the atrial tissue during the ablation procedure;
2. the safety and the procedure-related complications during or after the ablation procedure;
3. the long term procedural outcome after the ablation procedure.

Inclusion Criteria:

• Patients undergoing first-time catheter ablation for AF.
• Willing and able to provide informed consent
• Age greater than or equal to 18 years.

Exclusion Criteria:

• Patients who have previously undergone AF ablation
• Patients with more than mild mitral valve stenosis or mechanical mitral valve replacement
• Patients with chronic renal impairment with creatinine clearance rate of < 50