The effort test in angina pectoris.

The diagnosis of angina pectoris is usually based on the history alone, and in most cases this is conclusive. When, however, the quality, site, distribution, duration, or relationship to effort of a suspicious chest pain does not conform to classical coilcepts, a reliable objective test is needed. Two such tests have been used widely, the effort test as developed by Master (1942) and the anoxic test of Levy (1941). In the hands of most investigators both these tests have given positive results in only about half of cases in which the diagnosis was clinically certain. As the inhalation of 10 per cent oxygen requires special apparatus, is time-consuming, relatively expensive, not without danger, and causes electrocardiographic changes that differ from the normal only in degree, and as trials by our colleagues were not encouraging, it seemed more profitable to concentrate on improving the effort test. Using a simple modification of Master's technique, one of us (P. W.) soon realized that diagnostic ischmmic curves could be obtained in about 90 per cent of patients with clinically certain angina pectoris in whom the resting electrocardiogram was normal. The object of this paper is to present an analysis of these results together with a larger series of cases similarly investigated at the Institute of Cardiology.