Ventricular tachycardia: prediction of response to oral aprindine with intravenous aprindine.

Aprindine was administered both intravenously and orally to 25 patients with ventricular tachycardia refractory to conventional antiarrhythmic agents to test the hypothesis that the response to intravenous aprindine predicts the response to oral aprindine. Ten patients had incessant ventricular tachycardia and 15 had paroxysmal sustained inducible ventricular tachycardia. Eleven patients (43 percent) had conversion to sinus rhythm with intravenous aprindine (nine with incessant and two with paroxysmal sustained ventricular tachycardia). Thirteen patients (all with paroxysmal sustained ventricular tachycardia) manifested slowing of the tachycardia without conversion, whereas in one patient with incessant ventricular tachycardia, the tachycardia became less frequent and nonsustained after intravenous aprindine. All 11 patients who had conversion to sinus rhythm with intravenous aprindine remained free of ventricular tachycardia during oral treatment with aprindine (at 2 weeks) and for a follow-up period of 2 to 38 months (mean 16 +/- 13). Of the 14 patients who did not have conversion to sinus rhythm with intravenous aprindine, 12 had spontaneous or inducible ventricular tachycardia, or both, at evaluation 1 to 2 weeks after initiation of oral aprindine. In conclusion, administration of intravenous aprindine to patients with ventricular tachycardia is helpful in predicting the subsequent response to oral aprindine. In addition, the pattern of ventricular tachycardia predicted the response to aprindine; patients with incessant ventricular tachycardia tended to respond, and those with paroxysmal sustained ventricular tachycardia tended not to respond.