Antiarrhythmic effects of indecainide in a drug-resistant population with ventricular tachycardia at programmed electrical stimulation.

The antiarrhythmic properties of indecainide were studied in 15 patients with a history of a cardiac arrest or ventricular tachycardia. Programmed electrical stimulation studies were performed in nine men and six women with a mean age of 68 +/- 2 years and a mean left ventricular ejection fraction of 41 +/- 4%. All patients had inducible ventricular tachycardia by programmed electrical stimulation while off all antiarrhythmic therapy. Patients were then tested on procainamide, 1000 mg, administered intravenously, and ventricular tachycardia could be provoked in 10 of 15 patients. Indecainide was given intravenously, 1 mg/kg. Indecainide did not significantly change the baseline heart rate, blood pressure, and QTc interval from control values. The PR and QRS intervals were significantly prolonged. Twelve of 15 patients were still inducible for ventricular tachycardia on indecainide. Procainamide protected 5 of 15 patients against ventricular tachycardia induction. In patients still inducible on indecainide therapy, the ventricular tachycardia rate was significantly slowed, from 281 bpm to 224 bpm on indecainide and to 215 bpm on procainamide. The effects of this new class IC antiarrhythmic agent appears similar to procainamide in patients with serious life-threatening tachyarrhythmias.