Electrophysiologic studies in nonsustained ventricular tachycardia: relation to underlying heart disease.

Electrophysiologic studies were performed in 83 patients with spontaneous episodes of nonsustained ventricular tachycardia (VT). The clinical arrhythmia was reproduced in 63% (in 42 patients by programmed stimulation and in 10 by isoproterenol infusion). In 15 patients sustained VT could be reproducibly induced by programmed stimulation. Inducibility was related to the associated heart diseases: programmed stimulation induced VT in 25 of 33 patients (75%) with coronary disease, 6 of 18 patients (33%) with cardiomyopathy (dilated in 16, hypertrophic nonobstructive in 2), in 4 of 8 patients (50%) with mitral valve prolapse and in 7 of 24 patients (29%) without structural heart disease. Isoproterenol infusion induced VT in no other patient with coronary artery disease, 1 other patient with mitral valve prolapse, 3 patients with cardiomyopathy, and in 6 of 24 patients without structural heart disease. Sustained VT was induced only in patients with structural heart disease, and correlated with the presence of left ventricular aneurysms: Sustained VT was induced in 9 of 13 patients with left ventricular aneurysms. The study demonstrates that electrophysiologic techniques can reproduce episodes of nonsustained VT in most patients with spontaneous arrhythmias. Some patients who demonstrate only nonsustained VT spontaneously have inducible, sustained VT, most often in the setting of coronary artery disease and left ventricular aneurysms.