Repetitive ventricular response. Prevalence and prognostic significance

The purpose of this study was to determine the prevalence of repetitive ventricular responses caused by non-bundle-branch re-entry and bundle-branch re-entry in 47 patients with and in 50 patients without ventricular tachycardia. We also compared the prevalence of repetitive ventricular responses using two types of electrophysiological stimulation: single premature ventricular stimulation during sinus rhythm or atrial pacing, and single premature ventricular stimulation during ventricular pacing. In patients who had ventricular tachycardia, premature ventricular stimulation during ventricular pacing induced non-bundle-branch re-entry more often than during atrial pacing (70.2% versus 33.3%). Both methods of stimulation induced non-bundle-branch re-entry more often than during atrial pacing (70.2% versus 33.3%). Both methods of stimulation induced non-bundle-branch re-entry more often in patients who had ventricular tachycardia than in those who did not. In both groups of patients, bundle-branch re-entry was rare during atrial pacing and more common but equally prevalent during ventricular pacing. To determine if induced non-bundle-branch re-entry could identify patients at risk of developing future symptomatic ventricular tachycardia or sudden death, 59 patients who had a history of documented ventricular tachycardia had an electrophysiological study just before discharge and were followed for an average of 10.9 months. Non-bundle-branch re-entry induced during ventricular and atrial pacing had a predictive accuracy of 59% and 64%, respectively. The predictive accuracy of non-bundle-branch re-entry induced during atrial pacing appeared to be greater in patients who also had ventricular tachycardia induced during the same electrophysiology study. Our data indicate that: non-bundle-branch re-entry is induced more often during ventricular pacing than during atrial pacing and more often in patients who have a history of ventricular tachycardia than in those who do not; induction of non-bundle-branch re-entry during ventricular pacing is more sensitive and during atrial pacing is more specific; however, neither alone yields a predictive accuracy sufficiently high to make the test clinically useful; and (3) induced non-bundle-branch re-entry during atrial pacing associated with induced ventricular tachycardia may define a high risk group.