Optimal measurements for detection of coronary artery disease by exercise electrocardiography

Abstract

Exercise electrocardiogramswere analysed by digital computer in order to select criteria for optimal separation of normal subjects and patients with coronary artery disease. The results of a training group of 86 ostensibly healthy men and 52 patients were verified in a test series of 43 patients and 43 controls.All subjects had a normal QRS complex and ST--T segment at rest. ECG measurements included ST amplitudes and slopes at fixed intervals after the end of QRS. time-normalized ST amplitudes, the negative STareas, and Chebyshev waveform vectors. Visual reading of the ECG according to the classical criterion of a 0.1 mV horizontal ST depression yielded a sensitivity of SO and 5 1% and a specificity of 94 and 95% in the training group and the test group. respectively.Best results with a single ST measurement were obtained by the ST60 amplitude in lead X which was adjusted for heart rate according to the gradual ECG changes during exercise in the normal subjects. The sensitivity was 81% and the specificity 93%. In the test group these figures were 70 and 93%. Combination of measurements in linear discriminant functions resulted in some further improvement of these figures.

Significance of ‘recovery ST-segment depression’ in exercise stress test

“… 13 Simoons proposed a nomogram for STdepression during exercise regressed on heart rate. 14 Kligfield et al have proposed an ST-heart rate slope or index that considers ST shift relative to changes in heart rate during exercise as a means of diagnosing CAD. 15 Rautaharju et al 16 used the ST-integral to analyze the data from the Multiple Risk Factor Intervention Trial, and Detrano et al 17 compared careful visual readings with computerized readings of the exercise ECG.…”

A lesson from the controversy about heart rate adjustment of ST segment depression.

“…'1 Several methods have been proposed to normalize the ST segment depression by heart rate. [12][13][14][15][16][17] Historical View To obtain a historical perspective of the debate, we listed (Table 1) and analyzed all published reports in order of date of journal acceptance. Since 1977, 29 original reports have been published.3'5-9,12-35 The 13 years of history of ST heart rate adjustment research can be divided into four phases: the first steps (1977)(1978), the English period (1980)(1981)(1982)(1983)(1984), the American period (1985)(1986), and the period of expanding applications (1986)(1987)(1988)(1989)(1990)).…”

Computerized Exercise ECG in the Diagnosis of Critical Coronary Lesions

“…Combi nations of discriminating ST depression levels in the chest and limb leads were examined. The diagnostic significance of negative or biphasic T waves and ST depression in connection with a low maximal heart rate was also investigated [12]. Q waves were inter preted according to the Minnesota code [13] and the classes 1.1 and 1.2 were considered abnormal.…”

“…The ST amplitude was measured 60 ms after the end of the QRS complex (ST60). the reference level being the PQ level [12]. The PQ level was calculated as an average over 15 ms immediately before the QRS while the measurement on the ST segment was based on a symmetrical 15-ms interval.…”