We examined the value of cardiac pacing for assessing ventricular electrical instability and for predicting ventricular tachycardia and sudden death in 50 patients with refractory symptomatic ventricular tachycardia, 12 normal patients, and 48 survivors of a recent myocardial infarction. The repetitive ventricular response (two or more ventricular premature beats produced by a single ventricular pacing stimulus during control of heart rate with atrial pacing) was absent in all 12 normal patients but was present in 44 of the 50 patients (88 per cent) with recurrent ventricular tachycardia (P less than 0.001). Of the 48 survivors of myocardial infarction, 19 had repetitive ventricular responses. During the next 12 months 15 of these patients (79 per cent) had symptomatic ventricular tachycardia or sudden death, or both, as compared with four of 29 patients (14 per cent) who did not have repetitive ventricular responses (P less than 0.001). The repetitive ventricular response identifies patients with life-threatening ventricular instability, but it is still an investigational technic that should be used only with due precautions.
