Clinical value of the thallium-201 stress test sensitivity and specificity in the detection of coronary artery disease

Rest and exercise thallium-201 scintigraphy (²⁰¹Tl stress test), 90% submaximal treadmill exercise test (ECG stress test), and coronary angiography were performed on 49 patients with suspected coronary artery disease. When technically unsatisfactory and uninterpretable scintiphotos were excluded, the sensitivity (true positives/true positives + false negatives) of the ²⁰¹Tl stress test in detecting coronary artery stenosis ≥70% was 81%. The sensitivity of the ²⁰¹Tl stress test in detecting coronary artery stenosis ≥50% was 84&‰ However, when technically unsatisfactory and uninterpretable studies were considered as failures of the test to detect disease, the sensitivity of the ²⁰¹Tl stress test in detecting coronary artery stenosis ≥50% was 71%. The sensitivity of the ECG stress test was 92% in detecting stenosis ≥70% and 85%. in detecting stenosis ≥50% when non-diagnostic tests were excluded. However, when 11 non-diagnostic ECG stress tests were considered as a failure of the test to detect disease, the sensitivity of the ECG stress test in detecting coronary artery stenosis ≥50% was 64%. The sensitivity of the combined stress test in detecting coronary artery stenosis ≥50% was high whether or not technically unsatisfactory and uninterpretable studies were (89%) or were not (94%) included in the analysis. The specificity (true negatives,/true negatives + false positives) for ≥50% coronary artery stenosis was 90% for the ²⁰¹Tl stress test, 75% for the ECG stress test and 80% for the combined stress test. Combined ECG and ²⁰¹Tl stress testing detects a number of patients with significant coronary artery disease missed by ECG stress testing alone, primarily in those cases where the ECG stress test is non-diagnostic.