ObjectiveTo compare the safety and efficacy of ibutilide and amiodarone in converting post-coronary artery bypass grafting (CABG) new-onset atrial fibrillation (AF) to sinus rhythm. MethodsThis study was a prospective, single-blinded, randomized clinical trial. Totally 100 patients who met the inclusion criteria were enrolled and were intravenously treated with ibutilide (group A) or amiodarone (group B). In group A, Ibutilide was administered at a dose of 1 mg in 10 min, which was repeated after an interval of another 10 min if the arrhythmia was not converted; ibutilide was not given anymore no matter the conversion was achieved or not. In group B, amiodarone was administered at a dose of 5 mg/kg for the first 30 min, followed by 1 200 mg in the next 24 h; amiodarone was not given anymore no matter the conversion was achieved or not. Immediate conversion rate, conversion time and post-operative recurrence rate within 30 days were compared between the two groups. MethodsNo severe adverse reactions were observed in both groups. The immediate conversion rate of group A was significantly higher than that of group B (82% vs 58%, P<0.01), and the conversion time was significantly shorter than that of group B (66 min vs 660 min, P<0.01). The post-operative recurrence rates were not significantly different between the two groups within 30 days after operation (7.3% vs 6.9%,P>0.05). MethodsIbutilide and amiodarone are both safe in converting post-CABG new-onset AF to sinus rhythm, and ibutilide is more effective, more rapid in functioning and with a higher efficacy.