CONVERSION OF ATRIAL-FIBRILLATION TO SINUS RHYTHM USING ACUTE INTRAVENOUS PROCAINAMIDE INFUSION

The efficacy and safety of intravenous procainamide in the conversion of atrial fibrillation was investigated. A total of 114 patients witho ut severe heart failure were randomized to receive either intravenous procainamide (1 g over 30 minutes, followed by an infusion of 2 mg/min over 1 hour) or placebo in a double-blind trial. Digoxin (0.5 mg intr avenously) was administered to all patients who had not previously bee n receiving digoxin, Treatment was considered successful if sinus rhyt hm was restored within 1 hour after starting the infusion. Conversion to sinus rhythm was achieved in 29 (50.9%) of the 57 patients heated w ith procainamide and in 16 (28.1%) of the 57 who received placebo (P a pproximate to 0.012), When the duration of the atrial fibrillation was less than or equal to 48 hours, conversion to sinus rhythm was achiev ed in 29 (69%) of the 42 patients receiving procainamide and in 16 (38 .1%) of those receiving placebo (P approximate to 0.004), None of the patients with atrial fibrillation lasting greater than or equal to 48 hours converted to sinus rhythm in either group. Another factor that p layed a role in the restoration of sinus rhythm was the size of the le ft atrium: the smaller the left atrium, the larger the success rate. T he results of the study suggest that intravenous procainamide is an ef fective and safe means for the rapid termination of atrial fibrillatio n of recent onset and that its success rate is inversely related to th e size of the left atrium. However, the drug is ineffective in the con version of atrial fibrillation lasting more than 48 hours.