Quantitative adenosine ²⁰¹Tl single-photon emission computed tomography for the early assessment of patients surviving acute myocardial infarction

Background. We prospectively investigated whether adenosine ²⁰¹Tl tomography (SPECT) could determine the extent of coronary artery disease, the presence of jeopardized myocardium, and the risk for in-hospital cardiac events in 120 clinically stable patients early (5±3 days) after myocardial infarction. Methods and Results. All patients had coronary angiography and SPECT in close proximity. Adenosine SPECT identified 99% of infarct-related arteries and 82% of severely stenosed (≥70%) noninfarct arteries. Multivessel disease was accurately predicted in 69% of patients. Sixty-five percent of stenosed noninfarct arteries had matching thallium perfusion defects, and 92% of these were reversible. The specificity of adenosine SPECT was >90%. Thallium redistribution occurred often within infarct (59%) and noninfarct (92%) zones. The patency status of the arteries, however, did not predict the presence or extent of jeopardized myocardium. The perfusion defect size was larger (p=0.0001) in patients with (45±18%) than in those without (22±15%) in-hospital cardiac events. Furthermore, 90% of patients with events had a ≥20% perfusion defect compared with only 38% of those without events (p=0.0001). The positive-predictive accuracy for developing a cardiac event was 70% when the perfusion defect size was >30%. The ischemic defect also was larger in patients with (19±14%) than in those without (10±10%) events (p=0.001). The positive- and negative-predictive values for developing early postinfarction angina were 43% and 91%, respectively, when the ischemic defect was >12%. Conclusions. In selected low-risk survivors of myocardial infarction, early quantitative adenosine SPECT is safe and accurate in detecting and localizing coronary stenoses, assessing the extent of jeopardized myocardium, and determining subsequent risk for in-hospital cardiac events.