Whither the ST segment during exercise?

Abstract

The widespread popularity of using the ST segment response to exercise to detect individuals with ischemic heart disease is based largely on epidemiologic data and arteriographic correlative studies. It has been concluded that the ST segment response to exercise is highly accurate in predicting the presence or absence of coronary disease. However, this conclusion has been questioned in the light of recent coronary angiographic studies of asymptomatic subjects with positive exercise tests. The authors believe that the value of the ST segment response to exercise stress testing as an aid in the diagnosis of coronary artery disease is considerably more circumscribed than is commonly believed. First, it is of limited diagnostic value in symptomatic patients with a history of typical angina pectoris or a previously documented myocardial infarction since, despite the high predictive accuracy of a positive test result in such patients, the diagnosis is virtually established by history alone. In addition, a negative test result in such patients would be of dubious value because of the relatively low sensitivity of the test in a symptomatic population. A possible exception to these limitations would be the presence of a strongly positive stress test (e.g. ≥2.0 mm ST depression) which might indicate left main coronary artery disease or its equivalent. However, the test is insensitive when such criteria are adopted. Thus, detection of high risk subgroups of patients can only reliably be carried out by means of coronary arteriography. The ST segment response to exercise may have greater potential in patients with atypical chest pain syndromes. However, there is no reason to suspect that the sensitivity of the test is any greater than that observed in patients with a more typical history of coronary disease; hence, a negative test result again would be of little help in ruling out the presence of coronary disease. Finally, and most importantly, the test is of very limited diagnostic value when applied to asymptomatic subjects because of the large percentage of false positive results that occurs in this population.