Incidence and significance of decreases in systolic blood pressure during graded treadmill exercise testing.

The incidence of decreases in peak systolic blood pressure during treadmill exercise was investigated in 460 patients with definite or suspected coronary heart disease. All patients were studied with coronary cineangiography. Exercise was continued to one of the following end points: chest pain, 85 to 90 percent of the patient's age-predicted maximal heart rate, ventricular tachycardia or a sustained decrease of 10 mm Hg or more below the peak level of systolic blood pressure. Twenty-two patients with 75 percent or greater stenosis of one or more major coronary arteries manifested a decrease in systolic pressure 10 mm Hg or more during exercise. These included 15 (17 percent) of 88 patients with three vessel, 7 (7 percent) of 101 with two vessel and 0 of 90 with single vessel disease. The decrease in pressure was reproducible in the seven patients who underwent a second exercise test before alteration of therapy; this decrease was abolished in the six patients who exercised again after coronary bypass graft surgery.A decrease in systolic pressure of 10 mm Hg or more also occurred during exercise testing in 3 of 23 patients with noncoronary organic heart disease; all 3 had an obstructive cardlomyopathy that had not been suspected clinically. Only 1 of 158 subjects with chest pain and no demonstrable heart disease had a decrease in systolic blood pressure with exercise. Declines in blood pressure were not observed during 650 maximal exercise tests performed on 560 clinically normal men.In conclusion, if one excludes subjects with cardiomyopathy or significant heart valve disease, a sustained exercise-induced decrease in peak systolic blood pressure of 10 mm Hg or more is a highly specific sign of multiple vessel coronary artery disease. This phenomenon is best explained by acute left ventricular pump failure secondary to extensive myocardial ischemia.