Prevalence and significance of an abnormal S-T segment response to exercise in a young athletic population.

Treadmill stress electrocardiography is employed widely to detect underlying cardiovascular disease in asymptomatic persons. To determine the frequency and significance of an abnormal S-T segment response to exercise in young athletes with increased left ventricular (LV) mass induced by physical conditioning, 75 male isometrically trained athletes without evidence of heart disease (mean age 21 years) and 48 nonathletic young normal subjects were studied by M-mode echocardiography and exercise electrocardiography. Ventricular septal and posterior free wall thicknesses and calculated LV mass were significantly greater in athletes than in control subjects. An abnormal S-T segment response to exercise was present in 7 (9%) of the 75 athletes, all of whom had a LV mass greater than 275 g and in 5 the LV mass was above the 95th percentile of that of the control subjects. An abnormal treadmill exercise test result also was present in 3 (6%) of 48 control subjects. Seven of the 10 subjects with abnormal exercise test results had radionuclide angiograms at rest and with exercise, each of which was normal. It is concluded, therefore, that (1) abnormal exercise test results occur commonly in both athletes and non-athletes; (2) almost 10% of isometrically trained athletes have "false-positive" exercise electrocardiograms, suggesting that this test has major limitations in screening for underlying cardiovascular disease in athletes; and (3) in athletes, a relation was present between "physiologically" increased LV mass and false-positive exercise test results.