Background Atrial tachycardias (ATs) of a variety of mechanism can occur after or during catheter ablation for controlling atrial fibrillation (AF). In case of chronic AF (CAF) who underwent stepwise ablations, the predictors of macro-re-entry ATs with multiple circuits were not fully elucidated. Methods and Results 62 patients in whom macro-re-entry ATs were developed after 4 pulmonary vein isolation and complex fractionated atrial electrogram (CFAE) guided ablation procedure for CAF, were included. The 3-dimensional maps and electrograms during ATs were assessed whether AT had single or multiple loop circuits. Then, various factors related to cardiac structure and procedure were analyzed. Results: Of 62 patients with re-entrant ATs after ablation, 39 patients (62.9%) had multiple loop circuits (MLC), 23 (37.1%) had single one (SLC). 1. MLC groups had larger left atrial (LA) volume (131.49짹37.16 vs. 105.25짹21.59, P=0.0045) and LA size (45.238짹6.82 vs. 40.522짹4.31, P=0.004) measured by cardiac computerized tomography (CT) and 2-D echocardiography, respectively than SLC group. 2. There was no significant difference in the number of critical isthmus lines between 2 groups (2.84짹1.31 vs. 2.06짹1.28, P=0.06). 3. However, the proportion of patients underwent CFAE guided linear ablation with bidirectional block was higher in SLC compared with that in MLC (16/23, 69.5% vs. 21/39, 53.8%, P=0.005). Conclusion Larger LA size and volume before procedure, and higher incidence of incomplete bidirectional block after CFAE guided linear ablation are closely related to the occurrence of AT with multiple circuits post-stepwise CAF ablation.

Key Words : Atrial fibrillation, Catheter ablation, Atrial Tachycardia