Prognostic Value of Exercise 201 Tl Tomography in Patients Treated With Thrombolytic Therapy During Acute Myocardial Infarction

Abstract

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<.0005) 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.