Definition of Predicted Effective Antiarrhythmic Drug Therapy for Ventricular Tachyarrhythmias by the Electrophysiologic Study Approach: Randomized Comparison of Patient Response Criteri

Objectives. We sought to compare efficacies of therapy for ventricular tachyarrhythmias selected by programmed stimulation using two different patient response efficacy criteria: <5 versus <16 repetitive ventricular responses. Background. Therapy selection for ventricular tachyarrhythmias by programmed stimulation requires definition of patient response that predicts long-term efficacy. Such definitions have not been previously compared prospectively. Methods. Patients with sustained ventricular tachyarrhythmias were randomized to therapy selection using either the <5 or <16 repetitive response criterion of predicted effective therapy. The primary end point was sudden death or recurrence of ventricular tachyarrhythmi requiring intervention. Results. Predicted effective drug therapy was found for 23 (34%) of 68 patients randomized to the <5 criterion and 29 (36%) of 81 patients randomized to the <16 criterion (p = NS). Definition of therapy required 3.0 ± 1.6 drug trials (mean ± SD) in patients randomized to the <5 criterion and 2.9 ± 1.8 trials in patients randomized to the <16 criterion (p = NS). Patients randomized to the <5 criterion had lower 2-year probability of the primary end point (0.20 ± 0.05) than did patients randomized to the <16 criterion (0.33 ± 0.05, one-tailed p = 0.004). The advantage of the <5 criterion was also seen in subgroup analyses involving patients with and without an initial drug efficacy prediction. Conclusions. The programmed stimulation approach to the selection of antiarrhythmic therapy for ventricular tachyarrhythmias using patient response criterion of <5 repetitive ventricular responses results in lower probability of recurrence of ventricular tachyarrhythmi than does use of <16 repetitive response criterion.