The clinical electrophysiology of intravenous indecainide

The electrophysiologic effects of indecainide, a new class IC antiarrhythmic agent, were assessed in 10 patients with left ventricular dysfunction and inducible sustained ventricular tachycardia. Indecainide was administered intravenously in a dose of 60 to 90 mg/kg at a rate of 12.5 to 15 micrograms/kg/min. Indecainide had no effect on sinus node function or atrial and ventricular effective refractory periods. The AH (106 +/- 13 vs 130 +/- 24 msec, p less than 0.002) and HV (57 +/- 7 vs 73 +/- 19 msec, p less than 0.001) intervals were significantly increased. The QRS duration increased (102 +/- 9 vs 120 +/- 13 msec, p less than 0.001); however, the JT duration did not change. Induction of ventricular tachycardia was prevented in 1 of 10 patients. In the remaining nine patients, the ventricular tachycardia cycle length was significantly prolonged (248 +/- 47 vs 320 +/- 71 msec, p less than 0.001). Indecainide significantly depressed intracardiac conduction at several sites.