The role of ambulatory ST-segment monitoring in the diagnosis of coronary artery disease: comparison with exercise testing and thallium scintigraphy.

The value of ambulatory ST-segment monitoring in the detection of underlying coronary artery disease was investigated in one hundred consecutive patients who underwent exercise testing and coronary arteriography for chest pain. Forty-seven also had thallium-201 radioisotope imaging performed. Six of the 26 patients with normal coronary arteries and 52 of the 74 patients with significant coronary artery disease had ST-segment changes during 48 h of ambulatory monitoring (sensitivity 77%). In comparison, the sensitivity of conventional exercise testing was 73% and specificity was 81%. Previous myocardial infarction did not influence the results, but patients with poor left ventricular function more often had absence of ambulatory ST-segment changes. Three-vessel coronary artery disease was detected more efficiently (sensitivity 80%), compared with single vessel disease (sensitivity 50%). Thallium scintigraphy demonstrated defects of uptake in nine patients without ambulatory ST-segment changes (sensitivity 82%, specificity 71%). The majority of these patients had small inferior or posterior defects in thallium uptake. Only one patient with ambulatory ST-segment changes had normal coronary arteries and demonstrable spasm. Thus, ambulatory ST-segment monitoring is as valuable as stress testing in the detection of coronary artery disease and in addition helps detect patients with coronary spasm and normal coronary arteries.