Abstract: [Abstract] Objective To study the alteration of transmural heterogeneity of repolarization and its relationship to ventricular arrhythmia in the process of cardioversion of atrial fibrillation with ibutilide.Method .87 persistent atrial fibrillation cases with less than three months duration were enrolled randomizedly in group ibulitide and amiodarone to compare the success rate of cardioversion,analyze the alteration of the QT interval and Tpeak-end/QT before treatment and within 4 hours. Result The success rate of cardioversion of the group Ibutilide was significantly higher than the amiodarone group (61.7% vs 40.7%, P <0.05). QT interval of ibutilide group was significantly prolonged after treatment than before treatment, Tpeak-end/QT increased (P <0.01, P <0.05),and restored the level before treatment in 2 hours after treatment, and 1 hour, respectively (P> 0.05).QT interval of the amiodarone group was significantly prolonged (P <0.01), and continued to 4h after treatment, but Tpeak-end/QT did not change significantly before and after treatment (P> 0.05). Conclusion The success rate of atrial fibrillation cardioversion using ibutilide was significantly higher than amiodarone.But,after administration,ibutilide increased transmural heterogeneity of repolarization,and restored within 1 hour. Namely,it increased the risk of ventricular arrhythmias within 1 hour.

Key words: ibutilide, amiodarone, atrial fibrillation, transmural dispersion of repolarization, ventricular arrhythmia