Conversion of recent-onset atrial fibrillation to sinus rhythm: Effects of different drug protocols

In a population of 417 hospitalized patients, the efficacy and safety of different drug regimens administered to convert atrial fibrillation (AF) of recent onset (less than or equal to 7 days duration) to sinus rhythm were evaluated. All patients were in NYHA Class less than or equal to 2, and free of heart failure. They were randomly allocated to treatment with placebo in 221 patients; TV amiodarone, 5 mg/kg bolus, followed by 2.8 g/24 hours in 51 patients; IV propafenone, 2 mg/kg bolus, followed by 0.0078 mg/kg/min in 57 patients; p.o. propafenone, 600 mg p.o. in a single dose in 119 patients; and p.o. flecainide, 300 mg p.o. in (7 single dose in 69 patients. All patients were continuously monitored by Holter EGG, and the number of conversions to sinus rhythm was measured at 1, 3, and 8 hours. Results: (1) IV propafenone resulted in a higher conversion rate within 2 hour compared with the oral loading regimens of propafenone or flecainide, but the conversion rates at 3 and 8 hours were comparable, approximately 75% at 8 hours; 2) IV amiodarone was not different from placebo until 8 hours when it was associated with 57% of conversions; (3) conversion to sinus rhythm at 8 hours was observed in 37% of the placebo treated patients. Serious adverse effects occurred in few patients: two patients treated with flecainide and one treated with IV propafenone experienced left ventricular decompensation; one patient treated with placebo and two treated with flecainide had atrial flutter with rapid ventricular response. In conclusion, single-dose, oral loading with propafenone or flecainide are acceptable alternatives to conventional drug regimens in selected hospitalized patients. In addition, the measure of a placebo effect is mandatory in studies of recent-onset AF.