The efficacy of intravenous
procainamide, infused at 30 mg/min to a maximum dose of 20 mg/kg, in converting
atrial fibrillation was evaluated under electrocardiographic and blood pressure control in 21 patients. Nine patients had atherosclerotic
heart disease, seven had valvular lesions, five had
hypertension, and six had no apparent
heart disease. Nine patients (converters), who reverted to sinus rhythm at a mean dose of
procainamide of 13.3 +/- 3.6 mg/kg (mean plasma concentration, 7.4 +/- 3.9 micrograms/ml) had normal echocardiographic left atrial diameters. All but one of the remainder, the 12 non-converters, who received a mean
drug dose of 13.1 +/- 3.5 mg/kg (mean plasma concentration 13.9 +/- 7.6 micrograms/ml), had atrial diameters exceeding 4.0 cm. QRS and QTc intervals were not altered significantly in converters, but were prolonged significantly in non-converters. No serious side effects from the infusion were encountered. Intravenous
procainamide infusion appears to be a safe and rapidly effective method of converting recent-onset
atrial fibrillation to sinus rhythm in patients with normal left atrial dimensions.