2.3 Ablation procedure
The protocol for RFCA in our institution is described in the previous studies.19, 20 In brief, double trans-septal punctures were performed after positioning multi-polar catheters at the right ventricle, high right atrium, and coronary sinus. The EnSite NavX/Velocity (St. Jude Medical, St. Paul, MN) or CARTO (Biosense Webster, Irvine, CA) system were used for three-dimensional electroanatomic mapping. In patients with paroxysmal AF, the endpoint of the procedure was the elimination of all trigger focus. If non-pulmonary vein trigger was present after successful pulmonary vein isolation, additional ablation was performed to eliminate non-pulmonary vein trigger. Additional substrate modification was performed if the operator considered non-inducibility is more important than trigger point elimination. In non-paroxysmal AF, AF was induced by rapid atrial pacing after pulmonary vein isolation. The procedure was finished if sustained AF (lasting for more than five minutes) was not induced. Additional ablation such as complex fractionated atrial electrogram guided ablation, linear ablation, or low-voltage zone ablation were performed at the operator’s discretion if sustained AF was induced after pulmonary vein isolation.