Syncope and ventricular tachycardia in patients with ventricular preexcitation.

Four patients with ventricular preexcitation whose syncope initially was attributed to an arrhythmia utilizing the accessory pathway are presented. At electrophysiologic study, the electrophysiologic characteristics of the accessory pathways were considered unlikely to support a tachycardia of a rate sufficient to result in syncope. Programmed stimulation of the right ventricle, however, reproducibly induced ventricular tachycardia to which the syncope was subsequently attributed in 3 patients. The importance of identifying ventricular tachycardia as the cause of syncope in these patients is emphasized.