Exercise-induced atrioventricular block: A report of 2 cases and review of the literature

Exercise-induced AV block is an uncommon cause of chronotropic incompetence that tends to affect older patients, most of whom have evidence of conduction system disease on baseline ECG. Although the most common mechanism in the literature seems to be intrinsic disease of the His-Purkinje system, ischemia is an important etiology that should be considered and evaluated as clinically appropriate. Although exercise intolerance and dyspnea on exertion are common in an elderly population, it is important to consider EIAVB in the differential because the diagnosis is readily made with exercise testing, and therapy with permanent rateresponsive pacemaker implantation is effective for symptom relief and, possibly, for prognosis. Electrophysiologic testing, although probably not indicated for symptomatic patients who otherwise would undergo pacemaker implantation, may be useful in locating the site of AV block in asymptomatic patients.