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

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Abstract
To determine whether the severity of Tl-201 scintigraphic defects present within hours of acute myocardial infarction (MI) could be used to detect subsequent mortality, Tl-201 imaging was performed within 15 h 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 3 views (anterior and 40.degree. and 60.degree. left anterior oblique) by 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 mo. and 33% at last follow-up (average 9 mo.). Using the objective method, a high Tl defect score (7.0 or greater, corresponding to at least a moderate reduction of activity involving 40% of the left ventricle in 2 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 and 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 [creatine Kinase] > 1000 IU/l and moderate (vs. none or mild) left ventricular failure were associated with mortality. A high Tl defect score was significantly more predictive than any of these variables. Stepwise multivariate analysis showed that the Tl 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. Tl-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.