Exercise induced ventricular ectopics in patients with isolated congenital complete heart block and their association...

Treadmill exercise tests preformed on 13 patients with isolated congenital complete heart block are described. Premature ventricular contractions appeared with exercise in 5/13 patients. The 5 patients who developed ventricular ectopics with exercise had lesser increments in their junctional rates with exercise as compared to the remaining patients (P less than .025). Two of these 5 patients subsequently experienced syncope and required pacemaker insertion. The two groups of patients were indistinguishable in terms of age, sex, resting heart rates, presence or absence of cardiomegaly. The site of AV block appeared to be above the bundle of His in all instances (proven in 9/13). It is suggested that the association between ventricular ectopic activity and inadequate chronotropy with exercise could have a pathophysiological link and might indicate an unfavorable prognosis.