Improving diagnostic accuracy of the exercise test by combining R-wave changes with duration of ST segment depression...

To enhance the reliability of the exercise test in diagnosing both overall coronary artery disease and multivessel coronary artery disease, a discriminant function was obtained by means of stepwise linear discriminant analysis. Both electrocardiographic and nonelectrocardiographic factors were used to derive the discriminant function in a retrospective group of 231 patients, 168 of whom had angiographically defined coronary artery disease. The discriminant function converted into a simple exercise index or score was then applied to a retrospective group of 120 patients, 98 of whom had coronary artery disease. This index, combining R-wave changes with duration of ST segment depression and patient's sex, proved highly accurate in diagnosing coronary artery disease in male patients and in diagnosing the absence of coronary artery disease in female patients. When compared to standard ST segment criteria, the sensitivity and predictive value of the exercise index was significantly higher.