Reduction in sudden death and total mortality by antiarrhythmic therapy evaluated by electrophysiologic drug testing: criteria of efficacy in patients with sustained ventricular tachyarrhythmia.

Reports of the results of electrophysiologic testing of antiarrhythmic regimens have concentrated on inducibility of ventricular tachycardias during drug treatment. Many drug regimens, however, affect the tachycardia but fail to prevent its initiation. In this study, 258 patients who underwent serial electrophysiologic studies were followed up. The patients were divided into three groups on the basis of the results of electrophysiologic testing. Group 1 included patients in whom the initiation of ventricular tachycardia was prevented by the drug regimen. In groups 2 and 3 the ventricular tachycardia was still inducible with the discharge drug regimen. In group 2, the drug regimen demonstrated a beneficial response (that is, the tachycardia cycle length increased by greater than 100 ms and the tachycardia did not produce severe symptoms). In group 3, the regimen did not produce a beneficial response. During follow-up, recurrence of sustained ventricular tachycardia occurred in 7 (7%) of 103 group 1 patients but in 20 (39%) of 51 and 52 (50%) of 104 group 2 and 3 patients, respectively. However, the total mortality and sudden death mortality rates were substantially reduced in group 2 (12 and 4%, respectively) compared with group 3 (39 and 34%). In fact, the total mortality and sudden death mortality in groups 1 and 2 were not significantly different. Thus, under certain circumstances, a drug regimen that produces a beneficial response may be an acceptable clinical alternative, particularly when no regimen prevents induction of ventricular tachycardia.