Efficacy and electrophysiologic effects of oral sotalol in patients with sustained ventricular tachycardia caused by coronary artery, disease The efficacy of oral sotalol in preventing sustained ventricular tachycardia induction by invasive electrophysiological testing was assessed in 22 patients (60 + g years) with prior myocardial infarction. Programmed stimulation consisted of two baste drives followed by up to three extrastimuli at two right ventricular sites. At baseline, sustained monomorphic ventricular tachycardia was inducible in all patients. With sotalol (360 f 172 mg/day), it was no longer inducible in 10 patients; in 12 others, it remained inducible and its cycle length was only minimally prolonged (322 ‘I 42 to 345 + 44 msec, p < 0.05). Sotaloi markedly prolonged sinus cycle length, uncorrected QT interval, and right ventricular effective and functional refractory periods, but had little effect on ventricular conduction time either in sinus rhythm or with right ventricular pacing. There was no significant difference in drug dose or in electrophysiologic effect of drug that related to efficacy, nor was there any correlation between drug-induced prolongation of ventricular tachycardia cycle length and its effects. Six patients received oral sotalol over the long term without spontaneous recurrence of ventricular tachycardia (follow-up: 23 ? 16 months). These results demonstrate that sotalol is effective (45%) against sustained ventricular tachycardia induction at moderate doses and is well tolerated over a long term in the setting of remote myocardial infarction. However, its electrophysiologic effects as measured at invasive testing are not predictive of efficacy against ventricular tachycardia induction. (AM HEART J lgg2;123:82.) Teresa Kus, MD, PhD, Maria Aurora Campa, MD, Reginald Nadeau, MD, Marc Dubuc, MD, Wilhelm Kaltenbrunner, MD, and Mohammad Shenasa, MD, PhD. Montreal, QuBbec, Canada Sotalol is a noncardioselective P-adrenergic blocker that is also classified as a class III antiarrhythmic agent. In atrial, His-Purkinje, and ventricular tissue, it prolongs action potential duration and refractory periods but has no effect on the upstroke of the ac- tion potential.i? 2 It has been used successfully in the treatment of both supraventricular tachyarrhyth- mias3T 4 and against ventricular complex and repeti- tive ectopy. 5l 6 Using programmed ventricular stimu- lation, its effectiveness against the induction of ven- tricular tachyarrhythmias has been reported as between 18% and 67 % .7-16 Such a variation in effi- cacy rate may be the result of differences in stimula- From the Clinical Electrophysiology Laboratory, Research Center, SacrB- Coeur Hospital, and Departments of Medicine and Pharmacology, Univer- sity of Montreal. Received for publication Feb. 11, 1991; accepted July 2, 1991. Reprint requests: Teresa Kus, MD, PhD, Research Center, HBpital du Sa- cr&Coeur de MontrBal, 5400, Boul. Gouin West, Montreal, Qu&bec, Canada H4J lC5. 411133626 tion protocol, selection of patients resistant to mul- tiple antiarrhythmic drugs,8* g, il, i5, I6 or the pooling of patients with different cardiac pathology83 g, 11,13,l5 or of those with different types of inducible arrhyth- mias such as nonsustained ventricular tachycardia or fibrillation.7>9.12,14-16 When they are studied in homogeneous popula- tions of sustained ventricular tachycardia following remote myocardial infarction, wei have recently found that, for the Class Ia antiarrhythmic drugs procainamide and quinidine, prevention of ventricu- lar tachycardia induction is significantly related to drug-induced prolongation of ventricular effective refractory period. Thus prolongation of greater than 30 msec has an 88 % positive predictive value for drug efficacy. Similarly, Furukawa et al.i8 have correlated ventricular tachycardia noninducibility after intra- venous procainamide with prolongation of the ven- tricular effective refractory period. Greater drug-in- duced increments in ventricular effective and func- tional refractory periods have also been observed recently by Gillis et al.lg in patients responding to 82