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To determine to what extent the diagnostic accuracy of stress testing is influenced by the prevalence of coronary artery disease, we correlated the description of chest pain, the ST-segment response to exercise, and the results of coronary arteriography in 1465 men and 580 women from the registry for the Coronary Artery Surgery Study (CASS). A positive ST-segment response increased the pre-test risk by only 7 to 20%, whereas a negative ST-segment response decreased the risk by only 2 to 28%. Although the percentage of false positive results differed between men and women (12 +/- 1% vs 53 +/-- 3%, p less than 0.001), this difference was not seen in a subgroup matched for prevalence of coronary artery disease. Thus, the ability of stress testing to predict coronary artery disease is limited in a heterogenous population in which the prevalence of disease can be estimated through classification of chest pain and the sex of the patient. Additional multivariant linear discriminant function analysis on treadmill and angiographic data from 500 men with definite angina, 584 men with probable angina and 267 men with nonspecific chest pain identified independent predictors of presence and extent of coronary disease. The discriminant function developed clinical, and clinical and exercise risk indices for each patient subset. Probability curves demonstrated that exercise testing provided more diagnostic information than clinical data alone in patients with definite and probable angina. However, exercise testing in men with nonspecific chest pain was of limited value since disease prevalence was already low. We conclude that (a) analysis of the ST-segment response to exercise provides limited information regarding the diagnosis of coronary artery disease when used alone, and (b) use of other exercise variables in addition to clinical data improves the diagnostic ability of the exercise test in men with definite or probable angina.

Randomly selected cine arteriographic films of 30 diseased patients were read twice by each of three experienced observers. The intrareader variability was less than one-half of the interreader variability in reading the stenosis of segments of the coronary anatomy - a statistically significant difference (p less than 0.001). When extent of disease was evaluated by the number of diseased vessels, interreader variability was larger than intrareader variability (p less than 0.01). One reader read considerably less disease than the other two readers. The films were rated as to quality of the arteriographic films and the completeness of the study. In each case there was a greater interreader than intrareader variability (p less than 0.01). The films were rated good, acceptable, or poor. One of the three interpreters consistently gave worse ratings than the other two readers. It was particularly noteworthy that a larger amount of interreader variability was observed in both the left main coronary artery and the proximal left anterior descending artery.