The purpose of this study was to determine the prognostic value of thallium-201 exercise treadmill testing performed early after myocardial infarction in patients treated with thrombolysis. A retrospectively identified group of 210 patients treated with thrombolytic therapy alone (n = 131) or with thrombolytic therapy and coronary angioplasty (n = 79) who underwent tomographic thallium exercise treadmill testing 9 +/- 6 days after infarction were followed up for a median of 21 months. There was a high prevalence of abnormalities on the thallium studies. One hundred thirty-nine (66%) patients had a high-risk scan, defined as redistribution in at least one segment, a defect outside the infarct zone, or increased pulmonary uptake. Thirty-six (17%) patients underwent early revascularization. In the remaining 174 patients, there were 30 initial cardiac events (1 cardiac death, 11 nonfatal recurrent myocardial infarctions, and 18 revascularization procedures performed > 3 months after the thallium study). No single exercise or thallium variable was predictive of outcome. At 2 years there were no differences in survival free of any cardiac event for patients with a high- or low-risk thallium scan treated with thrombolysis alone (high-risk scan 86% and low-risk scan 80%; p not statistically significant [NS]) or with both thrombolysis and coronary angioplasty (high-risk scan 80% and low-risk scan 77%; p NS). Postinfarction exercise thallium variables associated with poor outcome in the prethrombolytic era were not associated with an adverse outcome in patients who had been treated with thrombolysis.(ABSTRACT TRUNCATED AT 250 WORDS)