Intravenous Procainamide for Predicting the Response of Sustained Ventricular Tachycardia to Type III Antiarrhythmic Drugs.

The use of serial electrophysiology studies to guide antiarrhythmic drug therapy in patients with ventricular tachycardia is both costly and time consuming. Intravenous procainamide administered during of the initial 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 tachycardia suppression after intravenous procainamide correlates with suppression on oral class III antiarrhythmic medications (amiodarone and sotalol). This study included all patients with sustained ventricular tachycardia who underwent an initial electrophysiology study including an acute suppression trial with intravenous procainamide and a subsequent restudy on oral amiodarone or sotalol. The response to intravenous procainamide was then compared with these type III antiarrhythmic medications. Between January 1993 and May 1995, 360 patients underwent electrophysiology studies for suspected or documented ventricular arrhythmias. One hundred patients (28%) had an inducible sustained ventricular tachycardia, and 26 patients received both intravenous procainamide and subsequently oral amiodarone or sotalol. Acute infusion of procainamide provided a highly specific method for predicting suppression of oral amiodarone and sotalol (82% and 100% respectively). However, several patients who were not suppressed by intravenous procainamide were suppressed by oral sotalol resulting in lower overall predictive accuracy 12/15 (80%) for amiodarone vs. 5/11 (45%) for sotalol treated group. 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 finding.