The results of treadmill exercise electrocardiograms were analyzed in 179 patients with coronary artery disease (greater than or equal to 50% diameter narrowing of one or more vessels). Exercise thallium-201 images were available in 141 of these patients. The exercise electrocardiograms were strongly positive in 51 patients, mildly positive (1 to 1.9 mm ST depression) in 28 patients, falsely negative in 23 patients and uninterpretable in 77 patients. The degree of exercise-induced ST depression did not correlate with left ventricular function, extent of coronary artery disease, exercise heart rates and rate-pressure product and extent of exercise-induced thallium-201 perfusion abnormality. However, the presence of a strongly positive exercise electrocardiogram only at heart rates of 140 beats/min or more or stage III or higher of the Bruce protocol was predictive of less extensive coronary disease and perfusion abnormalities. Thus, the magnitude of ST depression as such during exercise is not predictive of the extent of coronary disease, even in patients with 3 mm or greater ST depression. However, a strongly positive exercise electrocardiogram in the first two stages of the Bruce protocol or at a heart rate of less than 140 beats/min was related to the extent of coronary artery disease and impaired myocardial perfusion, and identified patients with more extensive coronary artery disease and jeopardized myocardium. Therefore, caution should be used in interpreting prognostic data on the basis of the degree of exercise-induced ST depression alone.

Ninety-nine patients with chronic coronary artery disease were prospectively evaluated to determine the reliability of historical, physical, electrocardiographic and radiologic data in predicting left ventricular ejection fraction. The left ventricular ejection fraction measured by radionuclide angiography was normal (greater than or equal to 50%) in 44 patients (group 1) and abnormal (less than 50%) in 55 patients; 36 of those 55 patients had an ejection fraction between 30 and 49% (group 2) and the remaining 19 patients had an ejection fraction of less than 30% (group 3). The ejection fraction was correctly predicted in 33 of the 44 patients (75%) in group 1 and in 47 of the 55 patients (85%) with abnormal ejection fraction (groups 2 and 3), but the degree of ventricular dysfunction was correctly predicted in only 19 patients (53%) in group 2 and in only 9 patients (47%) in group 3. Stepwise linear regression analysis was performed. The single most predictive variable was cardiomegaly as seen on chest roentgenography (R2 = 0.52). Four optimal predictive variables--cardiomegaly, myocardial infarction as seen on electrocardiography, dyspnea and rales--could explain only 61% of the observed variables in left ventricular ejection fraction. Thus, radionuclide ventriculography adds significantly to the discriminant power of the clinical, radiographic and electrocardiographic characterization of ventricular function in patients with chronic coronary heart disease.

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