EARLY RADIONUCLIDE SCANS FOR RISK ASSESSMENT IN SUSPECTED ACUTE MYOCARDIAL-INFARCTION

First-day thallium-201 myocardial perfusion scans and technetium-99m R BC gated scintiangiography were performed during the initial clinical and prognostic evaluation of 69 patients with suspected acute myocardi al infarction. Patients were monitored for clinical course, diagnosis confirmation, and use of specialty services (cardiac catheterization, percutaneous balloon angioplasty, and cardiac surgery) during hospital ization. Myocardial infarction, confirmed in 20 patients, was associat ed with significantly more left ventricular dilatation, lower ejection fractions, lower peak left ventricular filling rates, wall motion abn ormalities, and thallium-207 perfusion defects than nonmyocardial infa rction patients. Among all patients, left ventricular dilatation carri ed a relative risk of myocardial infarction of 5.8; low ejection fract ion and right ventricular dilatation were strongly associated with myo cardial infarction. A logistic model For congestive heart failure incl uded: left ventricular dilation, lower mean left ventricular filling r ates and time to peak filling rates, and abnormal thallium-201 lung:he art uptakes. Among nonmyocardial infarction patients, subsequent cardi ac catheterization was predicted by the presence of anterior thallium- 201 perfusion defects, Killip functional class II-III, and ischemia on EGG. These findings suggest that early detection of myocardial perfus ion defects and cardiac dysfunction by radionuclide scans enhances ini tial evaluation of suspected acute myocardial infarction patients. Add itional studies are needed to confirm these findings.