748-3 The Relationship Between the Location of Ischemic Perfusion Defects on Stress Technetium-99m Sestamibi SPECT Scintigraphy and the Location of a Subsequent Myocardial Infarction

Abstract

While the presence of ischemia on stress myocardial perfusion imaging has been shown to correlate with a future myocardial infarction (MI), it is unknown whether the location of the ischemia predicts the location of the subsequent MI. Therefore, 24 patients (83% male, mean age: 66 ± 13 yrs, 46% exercise, 54% pharmacologic stress) who had an enzyme proven myocardial infarction following a stress Tc-99m sestamibi (MIBI) SPECT imaging study were analyzed. The location of the MI, as determined by either standard electrocardiographic criteria, or by a new wall motion abnormality on echocardiography or contrast ventriculography, was related to the location of a reversible defect on the preceding stress/rest MIBI images. Two territories per patient—anterior (including anterolateral and anteroseptal) and inferior (including inferolateral and inferoseptal)—were assessed for the presence of a reversible defect, and for the location of the subsequent MI. In 5 patients, the location of the MI could not be determined, leaving 38 territories in the remaining 19 pts for analysis: Of 19 territories with a reversible defect, 9 (47%) were the site of a subsequent MI, compared with 3 (50%) of 6 territories with a fixed defect, and 6 (46%) of 13 territories with no defect (p = NS). The remaining patient had a lateral MI after MIBI images had shown a reversible apical defect. Thus, 10 (53%) of the 19 Ml's occurred in a territory that did not show ischemia on the preceding MIBI images. The location of ischemia on a stress Tc-99m sestamibi SPECT imaging study does not consistently predict the location of a future myocardial infarction. This is in accord with previous findings from coronary angiography that the most severe stenoses frequently do not correlate with the locations of subsequent infarctions.