Prognostic value of gated SPECT after reperfusion for acute myocardial infarction.

INTRODUCTION Myocardial reperfusion during the course of an acute myocardial infarction improves patients' short- and long-term prognosis; coronary blood flow is successfully re-established while preserving a large amount of at-risk muscle. Clinical evolution, however, varies. Presence of residual ischemia or viable myocardial tissue affects a patient's prognosis. Assessment by noninvasive methods allows better prognostic stratification. Cardiac-gated SPECT provides appropriate parameters to support treatment selection and monitoring of these patients. OBJECTIVES Assess the prognostic value--ability to predict occurrence of major cardiac events--of perfusion and cardiac function obtained by myocardial perfusion scintigraphy in myocardial infarction patients treated by any myocardial reperfusion method, whether pharmacological or surgical. METHODS Forty patients were included, mean age 58.8 ± 9 years, diagnosed with myocardial infarction. Participants were divided into two groups: primary percutaneous transluminal coronary angioplasty (15) or thrombolysis (25). All received myocardial perfusion scintigraphy with cardiac-gated SPECT to assess perfusion and left ventricular function, and were followed for six months with telephone interviews and review of clinical records. RESULTS In the 11 patients who had major cardiac events within six months of followup, a nonsignificant increase in perfusion defect extent was seen post reperfusion. Six (54.5%) of those with major cardiac events had anterior perfusion defects. In functional parameters, a significant increase in end-diastolic and end-systolic volumes and decrease in left ventricular ejection fraction were observed post stress (p = 0.006) and at rest (p = 0.001). Post-stress end-diastolic volume of ≥70 mL had a higher prognostic value for major cardiac events [sensitivity 100%; specificity 89%, area under ROC curve 0.835 (CI 0.702-0.969), p = 0.001]. CONCLUSIONS Cardiac-gated SPECT is useful to identify variables (including left ventricular systolic dysfunction and dilation of left cavities, particularly left end-systolic volume of >70 mL) predictive of major cardiac events in reperfused patients, independent of treatment modality.