Prognostic significance of repetitive ventricular response during programmed ventricular stimulation

To determine the incidence and prognostic significance of the repetitive ventricular response, a retrospective study was performed in 65 patients (49 male, 16 female, mean age ± standard deviation 55 ± 11 years) with coronary artery or myocardial disease and a variety of cardiac rhythm disorders. Programmed right ventricular stimulation was performed at a basic pacing rate of 120 beats/min using one (S₂) and two (S₂-S₃) premature stimuli. The data were analyzed as to the presence or absence of a repetitive ventricular response and the patients' outcome ([1] sudden death at 1 hour or less or documented ventricular fibrillation without myocardial infarction; [2] survival or death from noncardiac causes or nonsudden death).A repetitive ventricular response was observed in 23 (35.4 percent) of 65 patients after one and in 31 (48.4 percent) of 64 patients after two premature stimuli. It occurred in 9 of 9 patients with ventricular fibrillation and in 14 (82.4 percent) of 17 patients with ventricular tachycardia. The mean follow-up period was 76 ± 39 weeks. Sixteen patients were classified as dying suddenly; the remaining patients were considered surviving (or dying nonsuddenly). After one premature stimulus, a repetitive ventricular response was observed in 32.7 percent of patients surviving or with nonsudden death and in 43.8 percent of patients with sudden death or malignant ventricular arrhythmias. After two premature stimuli, the incidence of a repetitive ventricular response increased from 40.8 percent in patients surviving or with nonsudden death to 68.8 percent in patients with sudden death; 6 (12.2 percent) of 49 patients surviving or with non-sudden death and 9 (56.3 percent) of 16 patients with sudden death had more than three ventricular echo beats. All nonsurviving patients who demonstrated a repetitive ventricular response had intraventricular reentry. Depending on the rigidity of the criteria used (that is, the number of echo beats), the sensitivity of the test ranged between 37 and 88 percent and specificity ranged between 45 and 92 percent. The proportion of false positive results was high (33 to 66 percent); but the proportion of false negative results was low (8 to 18 percent).This retrospective study showed a correlation between sudden death and the incidence and number of repetitive ventricular responses (depending on the number of premature stimuli) and the type of reentrant beats (bundle branch reentry or intraventricular reentry).