Background: The hybrid therapy of atrial fibrillation (AF), catheter ablation of the inferior vena cava — tricuspid annulus isthmus and continuation of anti-arrhythmic drugs (AAD) have shown effectiveness for the treatment of atrial flutter (AFL) which results from anti-arrhythmic drug treatment of AF. But the long term follow-up data for the recurrence of AF has not been fully evaluated. This study was aimed at verifying long term results, and to determine the risk factors for the recurrence of AF in patients undergoing the hybrid therapy for anti-arrhythmic drug-induced AFL. Method: A total of 61 patients (age 57.1 짹 10.8, males 48) who had not have pre-ablative AFL episodes developed AFL after the administration of Class Ic/III anti-arrhythmic drug. Baseline clinical and echocardiographic data were collected and regular ECG & Holter monitoring were performed as scheduled. Results: During 85.7 짹 53.0 months, AF recurred in 27 of 61 patients (45.3%). Left atrial diameter were significantly different (p=0.027). The risk factors for the recurrence was pre-ablative LA size (odds ratio 7.5, CI of 95% 1.494 – 37.66, p=0.010). The patients with normal LA size (<44mm) had more AF free survival time than in patients of LA enlargement [mean 985 짹77 days vs. 304 짹 91 days, p = 0.0054]. The risk factors associated with the recurrence of AF in hybrid therapy was enlarged LA size. Conclusion: The careful selection of patients for hybrid therapy is warranted for long term AF free survival.