Programmed ventricular stimulation at a second right ventricular site: an analysis of 100 patients, with special reference to sensitivity, specificity and characteristics of patients with induced ventricular tachycardia.

One hundred patients without ventricular tachycardia (VT) initiated from the right ventricular (RV) apex were subjected to stimulation at the RV outflow tract. Sixty-two patients had no clinical arrhythmias, and 38 had sustained VT, ventricular fibrillation (VF) or cardiac arrest. Of the 38 patients with clinical arrhythmias, 22 (58%) had VT or VF induced from the RV outflow tract. Among the 62 patients without arrhythmias, 5 (13%) had polymorphic nonsustained VT or VF induced, which occurred with triple extrastimuli in all 5 patients. The 22 patients with VT initiated at the RV outflow tract were a heterogeneous group; 10 (45%) patients had cardiac diagnoses other than coronary artery disease (CAD). In contrast were patients whose VT was initiated at the RV apex (n = 84); in this group, 20 patients (22%) had diagnoses other than CAD (p less than 0.05). These 22 patients also were younger (mean age 46 years) than patients whose VT was initiated at the RV apex (mean age 58; p less than 0.01). Of the 16 patients with clinical VT and no induced arrhythmia from either RV site, 7 had CAD (4 with cardiac arrest), 5 had the long QT syndrome, 3 had dilated cardiomyopathy and 1 had valvular heart disease. In conclusion, stimulation at a second RV site increases the sensitivity of RV stimulation in patients with known VT and seldom initiates VT in patients without clinical VT.