Comparative response to isometric (static) and dynamic exercise tests in coronary disease

Abstract

Forty-six patients with arteriosclerotic heart disease manifested significant electrocardiographic changes (accompanied by angina in 35) during maximal exercise testing. These patients subsequently performed isometric exercise at levels representing various percentages of maximal voluntary contraction. Twenty-two patients also performed combined isometric and submaximal dynamic exercise. The prevalence rate of S-T segment changes during isolated isometric exercise depended on the percent of maximal voluntary contraction applied but was far lower than the rate observed during maximal dynamic exercise. Angina seldom occurred. Manifestations of coronary insufficiency appeared more often during combined submaximal dynamic and isometric exercise than during isolated isometric testing. Aortic pressure was measured in eight cases. Tension-time index and pressure-heart rate product were lower when maximal dynamic exercise was stopped owing to coronary insufficiency than at the end of isolated isometric exercise or combined submaximal dynamic and isometric exercise. However, the latter two tests produced fewer ischemic manifestations. The reasons for these discrepancies are discussed. We conclude that isometric exercise tests are unsuitable for diagnosing coronary insufficiency.