Sensitivity of various extrastimulus techniques in patients with serious ventricular arrhythmias

One hundred seventeen consecutive patients with a history of sudden cardiac death (group I = 62 patients) or recurrent symptomatic ventricular tachycardia (group II = 55 patients) as well as 11 control subjects (group III) were studied with programmed electrical stimulation over the past year. Programmed right ventricular stimulation included premature stimulation during atrial pacing (A₁V₂ mode) and during ventricular pacing (V₁V₂ mode), double ventricular extrastimuli during ventricular pacing (V₁V₂V₃), and brief bursts of rapid ventricular pacing (V_burst). Repetitive ventricular responses were defined as two or more ventricular premature beats produced by the final ventricular pacing stimulus occurring by intraventricular reentry. All but 13 patients were on antiarrhythmic therapy at the time of study. The incidence of repetitive ventricular responses induced by A₁V₂ pacing mode was 22% (22 of 104 patients) and that of sustained ventricular tachycardia was 1%. The sensitivity of inducing repetitive ventricular responses with V₁V₂ stimulation was 44% and that of sustained ventricular tachycardia was 7%; the sensitivity with V₁V₂V₃ pacing mode was significantly higher at 77% and 25%, respectively. When V₁V₂V₃ and V_burst stimulation were directly compared, the incidence of induction of repetitive ventricular responses and sustained ventricular tachycardia were comparable. The incidence of induction of repetitive ventricular responses and sustained ventricular tachycardia in groups I and II was similar; no repetitive ventricular responses were induced in group III patients. There was no significant difference in the sensitivity of either repetitive ventricular response or sustained ventricular tachycardia induction in patients with coronary disease compared with those with the diagnosis of noncoronary disease. We conclude that, contrary to an earlier report from our group, the incidence of induction of repetitive ventricular responses to single ventricular extrastimuli during atrial pacing is low in patients with a history of sudden death or recurrent ventricular tachycardia. The incidence of induction of repetitive ventricular responses and sustained ventricular tachycardia is highest using the V₁V₂V₃ and V_burst modes of stimulation.