Electrocardiographic changes during exercise in asymptomatic men: 3-year follow-up.

Electrocardiographic (ECG) changes during maximal bicycle exercise and risk factors for coronary heart disease (CHD) were studied in 510 male civic employees who were followed for 3 years. Clinical CHD developed in 15 (24.6 percent) of the 61 men with an ischemic exercise ECG on the initial examination and in 11 (2.4 percent) of the 449 subjects with a normal initial exercise ECG. A normal maximal exercise ECG is no guarantee that severe CHD does not exist and that a subject will not soon sustain major myocardial damage; and an ischemic exercise ECG does not necessarily indicate underlying CHD. In the former group angina was the most frequent clinical CHD episode; in the latter group, infarction. Among those with an abnormal initial exercise ECG, CHD was most likely to develop in association with a poor exercise capacity. Subjects with subsequent clinical CHD and those with abnormal ECGs after 3 years tended to have a higher frequency of risk factors; subjects whose abnormal ECGs reverted to normal after 3 years tended to have a lower frequency of risk factors.