Prognostic value of exercise ²⁰¹Tl tomography in patients treated with thrombolytic therapy during acute myocardial infarction

Background: Although myocardial perfusion scintigraphy is of proven value in the risk stratification of patients with a recent myocardial infarction who receive conventional therapy, its value in patients undergoing thrombolytic therapy remains controversial. Methods and Results: Seventy-one patients who received thrombolytic therapy for acute myocardial infarction had exercise ²⁰¹Tl tomography and coronary angiography before hospital discharge. Eleven (15%) of 71 patients had ischemic ST-segment depression during exercise, whereas 27 patients (38%) had scintigraphic ischemia. Twenty-five (37%) of 68 patients had a cardiac event consisting of either death (n=2), recurrent myocardial infarction (n=5), congestive heart failure (n=7), or unstable angina (n=11) during a follow-up of 26±18 months. Univariate predictors of cardiac events were as follows: Killip class (P=.04); left ventricular ejection fraction (P<.0005); total (P=.002) and ischemic (P<.005) perfusion defect size; percent thallium lung uptake (P=.001); presence of infarct-zone redistribution (P=.02); and multivessel coronary artery disease (P=.01). By multivariate analysis, the significant joint predictors of risk were ejection fraction (P<.0005) and ischemic perfusion defect size (P=.005). The combination of ejection fraction and thallium tomography added significant incremental prognostic information to the clinical data, whereas angiography did not further improve a model that included clinical, ejection fraction, and tomographic variables. Conclusions: Quantitative exercise ²⁰¹Tl tomography provides important incremental, long-term prognostic information in patients receiving thrombolytic therapy for acute myocardial infarction.