The magnitude of exercise‐induced ST segment depression and the predictive value of exercise testing

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Abstract
To assess whether the magnitude of exercise induced ST segment depression improves the predictive value of symptom limited exercise tests, and helps in the recognition of patients with more severe coronary heart disease, 90 consecutive patients with positive treadmill tests who also underwent selective coronary arteriography were reviewed. The predictive value improved progressively with the increasing ST depression and was most reliable in a select group of patients with normal electrocardiographic baseline who were not receiving digitalis (73% with ST depression 1 mm to 100% with ST depression 4 mm). The incidence of 2 and 3 vessel disease increased from 61 % with ST depression 1 mm in the overall population to 100% with ST depression 4 mm in the select group, and the incidence of left main trunk lesions increased, respectively from 6 to 30%. The prediction of 2 and 3 vessel disease was found to be significantly greater when patients were dichotomized into those with ST depression 4 mm compared to 4 mm.It is concluded that the magnitude of ST segment depression definitely improves the predictive value of exercise tests as well as the ability to recognize the patients with more severe disease. However, the markedly positive exercise tests cannot be utilized to accurately predict the presence of 2 or 3 vessel disease in individual cases unless ST depression attains 4 mm or more in patients with normal electrocardiographic baselines who are not taking digitalis. In this group, the ability to predict left main trunk lesion is approximately 30%.