Improved diagnostic performance of the exercise ECG test by computerized multivariate ST-segment/heart rate analysis

The exercise ECG test is the most widely used noninvasive method of evaluating myocardial ischemia. To determine whether it is possible to enhance its diagnostic power, the authors carried out computerized ECG measurements on 118 nonischemic patients and 38 ischemic patients with or without myocardial infarctions (MIs). Forty-seven (all ischemic and nine normal cases) underwent T1-201 SPECT. The diagnostic variables include ST-segment deviation, modified ST/HR-slope, ST-segment shape, and maximum heart rate. These variables are interrelated by means of compartmental and specific decision rules by computer. The diagnostic method discussed in this article is called the multivariate ST/HR analysis (MUSTA). When compared with MUSTA, the T1-201 SPECT images detected myocardial ischemia with a sensitivity of 100% and a specificity of 89%. Its diagnostic performance was influenced by neither previous MIs nor cardiac medication of the 47 patients tested. MUSTA was also compared to the nonmodified ST/HR analyses (ST60/HR and ST80/HR) and the standard exercise ECG test. It performed significantly better than these methods. The authors conclude that the multivariate ST/HR analysis is comparable to T1-201 SPECT in diagnosing myocardial ischemia among the study subjects. Furthermore, MUSTA is executed during the noninvasive exercise ECG test and is easily applied using an IBM/AT-compatible microcomputer. However, further evaluation of MUSTA with a separate and unselected patient population is needed.