Abstract
T HE diagnosis of early, uncomplicated coronary artery disease often poses a problem for the clinician, especially if the clinical history, usually his main basis for diagnosis, is silent or misleading. Consequently, various types of stress tests have been devised to aid in diagnosis. Of the stress tests enhancing the value of the electrocardiogram, the two-step exercise test of Master has, by far, been the most widely accepted and used. However, there has arisen in some quarters a controversy regarding the relative merits of the clinical history and the exercise electrocardiogram in the diagnosis of coronary insufficiency. Those who rely on the clinical history of angina pectoris regard the exercise electrocardiogram as purely confirmatory evidence, to be labeled as “false positive” or “false negative” whenever it disagrees with their clinical impression.’ This stand is upheld despite the two well known facts: that a good number (3870, in one study2) of patients who develop myocardial infarction have no previous symptoms and that the etiology of angina is at times apparently extracardiac. On the other hand, those who place greater faith on the exercise electrocardiogram would label a patient with angina and a negative exercise test as a case of “false angina,” and a patient without angina and a positive exercise test as a case of coronary insufficiency. Master’s own belief in his test is so great that he regards a negative test as practically an exclusion of coronary insufficiency.3,4 There are many who disagree with Master in this belief, for until now, the criteria for a “positive” or a “negative” test have not been satisfactorily resolved. Certainly, Master’s criteria have been subjected to so many criticisms that he has had to revise them several times.3-n The frequent revisions and the many conflicting opinions regarding which criteria are significant have compounded the confusion, to the detriment of the test itself. Long term follow-up studies of subjects who performed the two-step test (a postexercise test) have resolved some disputed points. Thus, ischemic S-T segment depression has been accepted by practically all investigators as indicative of coronary insufficiency. Follow-up studies have revealed that a very high percentage of subjects with such a finding develop frank coronary accidents within five to ten years.12-ls Furthermore, postexercise ischemic S-T segment changes were generally associated with advanced and diffuse occlusive coronary disease.17 However, the significance of the junctional type of S-T depression (J depression) and the reliability of the completely negative test as an assurance of a healthy coronary reserve have not yet been fully established. The morbidity or mortality from coronary disease several years after a postexercise test showing J depression has been shown to be significantly lower than tracings showing ischemic depression, and is still lower in subjects with a completely negative test.12-17 This has convinced many physicians that the J depression and the negative postexercise test practically indicate the absence of coronary insufficiency. But closer scrutiny of the results of these long term follow-up studies, such as those of Mattingly, quoted from Gubner,16 who found 87, 62.5 and 44 per cent
Published Version
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