Myocardial Ischemic Effects of Isometric, Dynamic and Combined Exercise in Coronary Artery Disease

Abstract

The electrocardiographic effects of isometric (handgrip) and combined isometric-dynamic (treadmill-plus-briefcase) exercise were evaluated and compared to a submaximal treadmill stress test in 140 patients with known or suspected coronary artery disease. Only 3 of 90 patients developed ischemic ST changes during handgrip, as opposed to 25 positive treadmill tests (p<0.01). Of 19 of 50 patients who were positive during the standard treadmill test, only 17 showed positive findings during the combined treadmill-briefcase test. Analysis of hemodynamic responses showed significant (p<0.01) differences between the handgrip and treadmill tests in terms of heart rate response (control 83±3 beats/minute, handgrip 105±4, treadmill 151±6), diastolic blood pressure (control 80±2 mm Hg, isometric 93±3, treadmill 81±3) and heart rate-systolic pressure product (control 9940±564 units, handgrip 15022±779, treadmill 22270+1147). In comparing treadmill and combined treadmill-briefcase tests, significant differences were seen in systolic blood pressure (control 114±2 mm Hg, treadmill 143±3, briefcase 155±3), diastolic blood pressure (control 83±2 mm Hg, treadmill 82±2, briefcase 89±2) and rate-pressure product (control 10134±373, treadmill 19624±777, briefcase 21201±798). Isometric exercise alone is much less likely to produce myocardial ischemia than vigorous dynamic exercise. Higher arterial diastolic (coronary perfusion) pressure may retard the development of myocardial ischemia during isometric or combined isometric-dynamic exercise in coronary patients. The electrocardiographic effects of isometric (handgrip) and combined isometric-dynamic (treadmill-plus-briefcase) exercise were evaluated and compared to a submaximal treadmill stress test in 140 patients with known or suspected coronary artery disease. Only 3 of 90 patients developed ischemic ST changes during handgrip, as opposed to 25 positive treadmill tests (p<0.01). Of 19 of 50 patients who were positive during the standard treadmill test, only 17 showed positive findings during the combined treadmill-briefcase test. Analysis of hemodynamic responses showed significant (p<0.01) differences between the handgrip and treadmill tests in terms of heart rate response (control 83±3 beats/minute, handgrip 105±4, treadmill 151±6), diastolic blood pressure (control 80±2 mm Hg, isometric 93±3, treadmill 81±3) and heart rate-systolic pressure product (control 9940±564 units, handgrip 15022±779, treadmill 22270+1147). In comparing treadmill and combined treadmill-briefcase tests, significant differences were seen in systolic blood pressure (control 114±2 mm Hg, treadmill 143±3, briefcase 155±3), diastolic blood pressure (control 83±2 mm Hg, treadmill 82±2, briefcase 89±2) and rate-pressure product (control 10134±373, treadmill 19624±777, briefcase 21201±798). Isometric exercise alone is much less likely to produce myocardial ischemia than vigorous dynamic exercise. Higher arterial diastolic (coronary perfusion) pressure may retard the development of myocardial ischemia during isometric or combined isometric-dynamic exercise in coronary patients.