Value of early thallium-201 scintigraphy for predicting mortality in patients with acute myocardial infarction.

To determine whether the severity of thallium-201 scintigraphic defects present within hours of acute myocardial infarction (MI) could he used to predict subsequent mortality, thallium-201 imaging was performed within 15 hours of the onset of symptoms in 42 patients with acute MI. Patients with pulmonary edema or shock were excluded. The extent of perfusion defect was determined in three views (anterior and 400 and 600 left anterior oblique) by both objective computer-assisted and subjective methods, and expressed as a summed defect score. Mortality for the patient group as a whole was 17% in hospital, 24% at 6 months, and 33% at last follow-up (average 9 months). Using the objective method, a high thallium defect score (7.0 or greater, corresponding to at least a moderate reduction of activity involving 40% of the left ventricle in two views) identified a subgroup of 13 patients in which mortality was 46% in hospital, 62% at 6 months, and 92% at last follow-up. Corresponding values for the 29 patients with lower objective defect scores were 3%, 7% and 7%, respectively (all p < 0.001). Similar results were obtained with the subjective scoring method. Certain clinical variables, including a history of prior myocardial infarction, anterior location of the current infarct, peak CK > 1000 IU/I and moderate (vs none or mild) left ventricular failure were also associated with mortality. However, a high thallium defect score was significantly more predictive than any of these variables. Stepwise, multivariate analysis showed that the thallium score alone was a better predictor than the best combination of these clinical variables, and no variable added to the predictiveness of the high defect score. These results suggest that thallium-201 scintigraphy may provide an accurate, rapid, noninvasive method for separating high-risk and low-risk subgroups of hemodynamically stable patients admitted with acute MI.