IRCT2013112215490N1 IRCT 2014-01-17 Arak University of Medical Sciences, Vice Chancellor for Research effect of amiodarone in reducing the incidence of atrial fibrilation Evaluation of the prophylactic effect of amiodarone in reducing the incidence of atrial fibrilation after coronary bypass graft surgery 2014-02-20 anticipated 204 Complete https://irct.ir/trial/14737 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Prevention, Other design features: patients are not aware of administered drug and only the written consent will be obtained. Responsible resident was not aware of the type of drug and drug has been prepared before by the anesthesiologist and would be used by responsible resident according to study group. 2-3 Atrial fibrillation. Intervention 1: Intervention 1. Amiodarone 300 mg intravenous bolus in 30-20 minutes and then 1 mg/kg in first 6 hours after surgery and 0.5 mg/kg IV infusion in next 18 hours. Intervention 2: Intervention 2. Intravenous normal saline as placebo.