INTRAVENOUS PROCAINAMIDE FOR PREDICTING THE RESPONSE OF SUSTAINED VENTRICULAR-TACHYCARDIA TO TYPE-III ANTIARRHYTHMIC DRUGS

The use of serial electrophysiology studies to guide antiarrhythmic dr ug therapy in patients with ventricular tachycardia is both costly and time consuming. Intravenous procainamide administered during of the i nitial electrophysiology study has previously been shown to be useful in predicting the efficacy of oral antiarrhythmic medications (type I and III). The purpose of this study is to confirm that ventricular tac hycardia suppression after intravenous procainamide correlates with su ppression on oral class III antiarrhythmic medications (amiodarone and sotalol). This study included all patients with sustained ventricular tachycardia who underwent an initial electrophysiology study includin g an acute suppression trial with intravenous procainamide and a subse quent restudy on oral amiodarone or sotalol. The response to intraveno us procainamide was then compared with these type III antiarrhythmic m edications. Between January 1993 and May 1995, 360 patients underwent electrophysiology studies for suspected or documented ventricular arrh ythmias. One hundred patients (28%) had an inducible sustained ventric ular tachycardia, and 26 patients received both intravenous procainami de and subsequently oral amiodarone or sotalol. Acute infusion of proc ainamide provided a highly specific method for predicting suppression of oral amiodarone and sotalol (82% and 100% respectively). However, s everal patients who were not suppressed by intravenous procainamide we re suppressed by oral sotalol resulting in lower overall predictive ac curacy 12/15 (80%) for amiodarone vs. 5/11 (45%) for sotalol treated g roup. We conclude that the acute infusion of procainamide may help to predict ventricular tachycardia suppression after oral amiodarone and sotalol. A larger prospective trial is warranted to confirm this findi ng.