[The value of thallium myocardial scintigraphy (single photon emission computerized tomography, SPECT) for diagnosis of ischemia after myocardial infarct].
BACKGROUND: Patients with prior myocardial infarction and additional stenosis in noninfarct-related coronary artery have a high risk of reinfarction. Angina pectoris and exercise electrocardiography have a low sensitivity und specificity in detection of such coronary artery stenosis. We assessed the diagnostic value of tomographic thallium scintigraphy for detection of ischemia in myocardium not supplied by the infarct-related coronary artery. PATIENTS AND METHOD: In 77 patients with prior myocardial infarction (59 patients with acute infarction, 18 patients with chronic infarction) sensitivity and specificity of angina pectoris, exercise electrocardiography and tomographic thallium scintigraphy was determined. Coronary arteriography was the gold standard method. The predictive value of tomographic thallium scintigraphy was assessed by serial testing. RESULTS: Tomographic thallium scintigraphy detected 40 of 51 patients with significant stenosis in noninfarct-related coronary artery (sensitivity: 78%; positive predictive value: 83%). In 18 of 26 patients with no additional significant stenosis tomographic thallium scintigraphy did not show ischemia at a distance (specificity: 69%; negative predictive value: 62%). In sequential testing tomographic thallium scintigraphy did not give any additional diagnostic information in patients with angina pectoris. In patients without angina pectoris exercise electrocardiography had a high positive predictive value (90%), tomographic thallium scintigraphy did not yield a higher positive result. Only in patients without angina pectoris and negative exercise electrocardiographic findings tomographic thallium scintigraphy was helpful: 16 of these patients had an additional coronary artery stenosis and were detected by tomographic thallium scintigraphy only (positive predictive value: 75%); in 13 of 17 patients without an additional coronary artery stenosis thallium scintigrams were negative (negative predictive value: 76%). CONCLUSION: The presence of significant coronary artery stenosis in noninfarct-related vessels can be predicted by serial noninvasive testing. Tomographic thallium scintigraphy has its place in postinfarction patients without angina and with negative exercise electrocardiographic findings.