Programmed ventricular stimulation in patients without spontaneous ventricular tachycardia

Programmed ventricular stimulation was performed in 52 patients who had not had a documented or suspected episode of spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF). Programmed stimulation with up to three extrastimuli was performed from the right ventricular (RV) apex in all patients and from the left ventricular (LV) apex in 14 patients. A maximum response of one to five intraventricular reentry beats was induced in 52% of patients. Nonsustained VT (six or more repetitive beats terminating spontaneously within 30 seconds) was never induced in the 16 patients without structural heart disease but was induced (usually with triple extrastimuli) in 45% of nine patients with mitral valve prolapse and in 37% of 27 patients with other types of heart disease. Sustained VT was never induced; however, sustained VF was induced in two patients. During programmed RV and LV stimulation with up to three extrastimuli (with 2 msec pulses, 5 mA in intensity), (1) a maximum response of one to five repetitive beats is a nonspecific finding of no predictive value; (2) nonsustained VT was not induced in patients without structural heart disease who had not had spontaneous VT; (3) nonsustained VT was frequently induced in patients with structural heart disease who had not previously been known to have had VT; (4) the induction of sustained VT appears to be a response specific to patients who have had spontaneous VT or VF; and (5) sustained VF can be induced infrequently in patients who have never had spontaneous VT or VF.