FREQUENCY OF PRESUMED REENTRY WITH AN EXCITABLE GAP IN SUSTAINED VENTRICULAR-TACHYCARDIA UNASSOCIATED WITH CORONARY-ARTERY DISEASE

In sustained ventricular tachycardia (VT) unrelated to coronary artery disease, the incidence of reentry with an excitable gap was examined, and rapid pacing was performed to entrain VT in 48 episodes in 42 con secutive patients. Coronary artery disease was excluded by coronary ar teriography. The underlying heart diseases were postoperative congenit al heart diseases (n = 5), dilated (n = 7) or hypertrophic (n = 4) car diomyopathy, arrhythmogenic right ventricular dysplasia (n = 6) and mi scellaneous heart diseases (n = 5), as well as no demonstrable heart d isease (n = 15) in which 8 patients had verapamil-responsive VT. Excep t for 1 patient with hypertrophic cardiomyopathy, 48 morphologically d istinct monomorphic sustained VTs were induced. Twenty-five VTs showed right bundle branch block morphology and 23 left bundle branch block morphology, and VT was entrained in 84 and 96%, respectively. The over all incidence of the entrainment was 89.6% (43 of 48 monomorphic VTs), and the frequency of the ability to entrain VT ranged between 33.3 an d 100% in the subgroups. The lowest frequency was found in hypertrophi c cardiomyopathy. In conclusion, most inducible monomorphic sustained VT unassociated with coronary artery disease was presumed to be reentr y with an excitable gap.