Abstract: Objective:To observe the effects and safety of intravenous injection amiodarone on acute coronary syndrome(ACS) with fast atrial fibrillation(AF).Methods:Forty-eight cases with ACS with fast AF were treated with intravenous injection of amiodarone,and maintained at 0.5-1.0 mg/min for 0.5-24 hours.The reversion of AF,the ventricular rates,blood pressure and side-effects were observed at 30 min,2 hour and 24 hour after treatment.Results:Compared with pretreatment,36 cases were reverted(the reversion rates as 75%) and the ventricular rates were apparent decline after treatment(P0.01).Systolic blood pressure change was not apparent,but the diastolic blood pressure after treatment was lower than that of pre-treatment(P0.05),The reversion rates of cardiac function with grade Ⅰ and Ⅱ(82.9%) were higher than that of cardiac function with grade Ⅲ and Ⅳ(46.2%)(P0.05).Five cases(10.4%) with sinus bradycardia and 4 cases(8.3%) with low blood pressure after reduction or stopping the drug,which could recover after giving dopamine were observed.Conclusions:Treatment of ACS with fast AF with intravenous injection of amiodarone have higher reversion rates and fewer side-effects.