Intravenous amiodarone vs propafenone for atrial fibrillation and flutter after cardiac operation.

The safety and efficacy of amiodarone and propafenone in converting atrial fibrillation or flutter after cardiac surgery were compared in a randomized double-blind trial. Eighty-four patients with sustained atrial tachyarrhythmias of more than 30 min' duration, stable hemodynamic status and neither preoperative atrial arrhythmias nor treatment with other antiarrhythmis drugs, were randomized to receive amiodarone (46 patients: 5 mg/kg over 15 min and then 15 mg/kg over the subsequent 24 h for non-converting) or propafenone (38 patients: 2 mg/kg over 15 in and then 10 mg/kg over the subsequent 24 h for non-converting). Nine of the 46 patients (19.5%) receiving amiodarone converted to sinus rhythm within 1 h following bolus injection compared with 17 of 38 patients (44.7%) treated with propafenone (P < 0.05). Within the 24 h study, 38 of 46 patients (82.6%) given amiodarone and 26 of 38 patients (68.4%) given propafenone were converted to sinus rhythm (P = NS). A significantly progressive reduction in ventricular response, already evident at 10th min from the start of treatment, was achieved in both groups of patients. Side effects occurred in six patients given propafenone (15.7%) and in five given amiodarone (10.8%) (P = NS). The two drugs were equally effective in converting postoperative atrial fibrillation and/or flutter after 24 h although propafenone was superior within the first hour.