[Graded criteria to assess the effectiveness of anti-arrhythmia therapy in patients with ventricular tachyarrhythmia by serial electrophysiological testing].

To test whether rendering ventricular tachycardia more difficult to induce during antiarrhythmic therapy can be considered as sufficient to predict long-term efficacy in patients with ventricular tachyarrhythmias, 95 patients were studied using a graded stimulation protocol (single and double premature stimuli during sinus rhythm and ventricular drive of 120, 140, 160 and 180 b.p.m.). After control, the effects of oral antiarrhythmic drugs on the ability to induce ventricular tachycardia were assessed. Median number of drug trials was 4 per patient. Following antiarrhythmic therapy 4 subgroups of patients were identified. In 36 patients there was no change in inducibility (group 1), whereas in 18 patients ventricular tachycardia was made more difficult to induce, i.e. a sustained ventricular tachycardia was inducible at a basic drive at least 40 b.p.m. faster than control (group 2). In 34 patients, ventricular tachycardia induction was suppressed (group 3) and in 7 patients with non-sustained ventricular tachycardia only 3 to 7 beats were induced after treatment (group 4). During follow-up of 12 +/- 11.2 months 10 patients of group 1 had a recurrence of ventricular tachycardia and 6 died suddenly, whereas in group 2 only one patient died suddenly and in group 3 2 patients had a recurrence of ventricular tachycardia (group 1 versus 2 and 3 p less than .001, Mantel-Cox and Breslow; group 2 versus 3 no difference). Thus, making ventricular tachycardia more difficult to induce is a sufficient criterion to predict long-term efficacy of an antiarrhythmic drug regimen.