BACKGROUND: Postoperative atrial fibrillation occurs in 5% to 65% of patients undergoing cardiac surgery. Although postoperative atrial fibrillation is often regarded as a temporary, benign, operation-related problem, it is associated with a twofold to threefold increase in risk of adverse events, including permanent or transient stroke, acute myocardial infarction, and death.

METHODS: This randomized, controlled, double-blinded trial included 250 eligible consecutively enrolled patients undergoing coronary artery bypass grafting (CABG). They received 300 mg of amiodarone/placebo administered intravenously over 20 minutes on the first postoperative day and an oral dose of 600 mg of amiodarone or placebo twice daily for the first 5 postoperative days.

RESULTS: The patients in amiodarone prophylaxis experienced a reduction in risk of atrial fibrillation of 14% (95% confidence interval [CI], 5.0% to 24%), with the number needed to treat at 6.9 (95% CI, 4.2 to 20), and the results for symptomatic atrial fibrillation showed a risk reduction of 18% (95% CI, 9.4% to 26), with the number needed to treat at 5.7 (95% CI, 3.9 to 11). Of the patients who developed atrial fibrillation in the placebo group, 84% experienced a symptomatic attack versus only 43% in the amiodarone group.

CONCLUSIONS: Postoperative prophylaxis with a high dose of oral amiodarone after an intravenous bolus infusion is a safe, practical, feasible, and effective regimen for CABG patients. It significantly diminishes the occurrence of postoperative atrial fibrillation.