Repetitive responses to ventricular extrastimuli: incidence and significance in patients without organic heart disease.

Of 110 patients without organic heart disease undergoing electrophysiological evaluation, 72 patients (65%) manifested some form of repetitive ventricular response to ventricular stimulation. In 58 (53%) bundle branch re-entry was induced and in 19 patients (17%) intraventricular re-entry. In five patients (4%) both types of repetitive responses were initiated. The indication for study was documented as ventricular tachycardia or fibrillation in 13% of the patients, supraventricular tachycardia in 51% and Wolff-Parkinson-White syndrome, syncope or conduction disturbances in the remaining patients. The incidence of clinical and inducible ventricular tachycardia or fibrillation was 8 and 2% respectively, in the group of patients manifesting only bundle branch re-entry, 37 and 32% in patients with intraventricular re-entry and 8 and 11% in patients without repetitive ventricular responses during ventricular stimulation. The predictive value of intraventricular re-entry as an indicator of severe ventricular arrhythmias was 36%. We conclude that in our population of patients without organic heart disease, bundle branch re-entry is a frequent finding and is not related to ventricular arrhythmias, that intraventricular re-entry is less frequent and although it is associated with a higher incidence of ventricular tachycardia or fibrillation, it is a poor predictor of these arrhythmias in this study population.