Elsevier

American Heart Journal

Volume 94, Issue 4, October 1977, Pages 463-470
American Heart Journal

Post-exercise thallium-201 myocardial scanning: A clinical appraisal*

https://doi.org/10.1016/S0002-8703(77)80041-0Get rights and content

Summary

Post-exercise myocardial scanning with thallium-201 provides an additional, noninvasive technique for the detection of coronary artery disease which may be especially useful in situations where treadmill testing is likely to be nondiagnostic. Tl-201 scans are sensitive in the presence of severe, discrete single vessel coronary disease, or extensive, diffuse triple vessel disease. In addition, perfusion scanning provides an estimate of regional flow deficits in the myocardium complementary to the anatomic information derived from arteriography and supplementary to the functional information obtained from stress testing. However, our present inability to independently corroborate the status of myocardial perfusion in the clinical setting somewhat limits the value of this information.

In this series, 20 of 42 treadmill tests were nondiagnostic, while 2 of 15 patients with severe coronary disease had false negative treadmill tests. Nine of nine patients with single vessel coronary disease had positive myocardial scans with good anatomic correlation between the location of the scan defect and the site of anatomic disease on angiogram. Eighty-three per cent of patients with double and triple vessel disease had positive scans, although anatomic correlation was poorer in these cases. Despite the theoretical advantages of performing both rest and exercise scans, such comparisons were found to be of limited value using this isotope in the clinical setting. The very differences in blood flow and, hence, isotope uptake which should account for rest vs. exercise changes in the presence of ischemic disease, and the low energy of emission of Tl-201, led to poor image clarity and resolution at rest. Underlying segmental wall motion abnormalities at rest could not always be excluded as the cause of a scan defect; exercise rarely altered such a defect recognizably. No false positive but one false negative scan was obtained among patients with severe coronary disease.

The role of Tl-201 myocardial perfusion scanning in detecting mild coronary disease, and in evaluating postoperative graft status, remains uncertain. The effect on perfusion of mild coronary obstructive lesions cannot be accurately predicted. One patient, with minimal coronary disease and normal ventricular contraction, had a positive myocardial scan; this was considered to be a false positive. Among post-aortocoronary bypass patients, positive scans related to graft occlusion, significant unbypassed native coronary disease, segmental ventricular wall motion abnormalities, or a combination of these factors.

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    *

    Supported in part by grant HL 14622-03 from the National Heart and Lung Institute.

    1

    From the Departments of Cardiology, Nuclear Medicine, and Cardiovascular Surgery, Presbyterian Hospital, Pacific Medical Center, San Francisco, Calif.

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