Noninvasive testing in the evaluation of myocardial ischemia: agreement among tests
HK Hammond,
TL Kelly,
and
VF Froelicher
The purpose of this study was to investigate the relations among four exercise-induced phenomena--angina, ST segment depression, decrease in ejection fraction and thallium perfusion defects--and to determine their impact on aerobic capacity. One hundred fifty-six men (mean age 52 +/- 8 years) with documented coronary heart disease were studied with radionuclide ventriculography during supine bicycle exercise, thallium scintigraphy and treadmill testing with computerized electrocardiography and maximal oxygen uptake. Of 624 administered tests, 243 results (39%) were considered to indicate ischemia. The average number of abnormal tests was 1.6 per patient and, when considered as continuous variables, their results correlated poorly. Correlations did not improve when adjusting for heart rate achieved or by eliminating patients with coronary artery bypass surgery or myocardial infarction. Statistical methods of comparing degree of interest agreement yielded surprisingly weak relations among the four tests of ischemia. Treadmill performance was markedly impaired by angina, but much less impaired by other indicators of ischemia. It is concluded that the usual test responses implying ischemia have weak agreement when uniformly applied to patients with known coronary artery disease.
