Role of adenosine thallium-201 tomography for defining long-term risk in patients after acute myocardial infarction

Objectives. This study prospectively evaluated whether early assessment with adenosine thallium-201 tomography could better refine risk stratification on the basis of absolute extent of myocardial ischemi in postinfarction patients in clinically stable condition. Background. Postinfarction patients are at increased risk for subsequent cardiac events. However, identifying high risk patients among those with residual myocardial ischemi is suboptimal. Methods. All 146 patients enrolled underwent assessment of left ventricular function and had adenosine tomography performed early (mean [±SD]5 ± 3 days) after infarction. Excluded from analysis were 51 patients with revascularization after scintigraphy and 3 lost to follow-up. Statistical risk models were therefore generated from the remaining 92 patients. Results. Cardiac events occurred in 30 (33%) of 92 patients over 15.7 ± 4.9 months. Univariate predictors of all events were quantified perfusion defect size (p < 0.0001), absolute extent of left ventricular ischemi (p < 0.000001) and ejection fraction (p < 0.0001). Risk was best predicted by Cox analysis on the basis of 1) absolute extent of ischemi and ejection fraction (chi-square 24.6); 2) percent infarct zone ischemi and ejection fraction (chi-square 24.4); or 3) total perfusion defect size and percent infarct zone ischemi (chi-square 18.9). The variables that predicted all cardiac events were equally powerful at predicting only death and nonfatal reinfarction. Death was best predicted by total perfusion defect size. Conclusions. Risk analysis of individual patients early after infarction is feasible on the basis of the quantified extent of scintigraphic ischemi and severity of left ventricular dysfunction.