Electrocardiographic changes in clinically normal older men following near maximal and maximal exercise.

SUMMARY This study was undertaken to compare the incidence of electrocardiographic abnormalities associated with a near maximal and a maximal exercise test, because of previous reports of high incidence of such abnormalities among older men. One hundred fourteen male volunteers ranging in age from 40 to 75 years were studied by both near maximal and maximal exercise testing. All subjects were considered normal by history and physical examination. Electrocardiographic responses to exercise testing were monitored by telemetered bipolar leads during and immediately after exercise and by standard electrocardiographic leads made during the recovery period between 30 seconds and 5 minutes after the termination of exercise. Both near maximal and maximal exercise testing were accomplished without significant complication. The incidence of segmental ST depression following the near-maximal test was less than 1%. The incidence of segmental ST depression following the maximal exercise test was 5.2% (6-114). Only one of the five abnormalities detected during or after maximal exercise persisted for more than 30 seconds after the conclusion of exercise. Since such changes occur in a high percentage of patients with heart disease, such changes appear to have a high degree of specificity for some form of cardiac abnormality. Additional Indexing Words: Maximal heart rate related to age Exercise test safety precautions Resting ECG abnormalities in asymptomatic v Timing of ECG abnormalities during test THE SENSITIVITY of exercise electrocar-diographic testing in the diagnosis of angina pectoris can be increased by utilizing exercise levels of near maximal severity.1-3 There is doubt, however, as to the relative specificity, in a diagnostic sense, of the changes that occur under such conditions. Bellet and Muller4 and Doan and associates5 have reported that a Graded exercise test (GXT) high percentage of "healthy" men 40 years or over will develop segmental ST depression following exercise of "maximal" tolerated severity. This experience is in apparent sharp disagreement with that of Sheffield and associates ,' and of Mason and associates.2 6 These authors have reported that exercise of <'near maximal" severity results in flat or sagging ST depression in a very small percentage (less than 1%) of clinically normal men whose ages were similar to those studied by Doan and associates.5 The present study was designed to compare directly the responses of older males to a two-step exercise test of "near-maximal" severity (GXT) with the multistaged "maximal" treadmill test utilized by Doan and his colleagues.5