The additive value of gated SPET myocardial perfusion imaging in patients with known and suspected coronary artery disease

In myocardial perfusion scintigraphy, the clinical significance of fixed de fects presents some difficulty. In this study, we evaluated whether additio nal information on left ventricular function assessed by quantitative gated single-photon emission computed tomography (gated SPET) would increase the diagnostic yield of the study in such patients. We studied 55 patients wit h a previous myocardial infarction and 20 patients without a previous myoca rdial infarction using gated SPET Tc-99(m)-tetrofosmin myocardial perfusion imaging. Each patient had to have a persistent perfusion defect consisting of at least three contiguous segments in the same vascular territory. The left ventricle was divided into 20 segments which were analysed for perfusi on and wall thickening on a 4-point severity scale. Of the 55 patients with myocardial infarction, 19 (35%) patients showed preserved wall thickening in the region of the previous infarction with fixed perfusion abnormalities , which suggested residual myocardial viability. In the 20 patients without myocardial infarction, preserved wall thickening was seen in 10 (50%) pati ents with fixed perfusion defects, suggesting an attenuation artefact. Conv ersely, in 16 (29%) patients in the myocardial infarction group and two (10 %) patients in the non-myocardial infarction group normal perfusion was ass ociated with severely diminished wall thickening possibly due to stunning. We found an excellent correlation between wall thickening and left ventricu lar ejection fraction both for the patients with myocardial infarction and the patients without myocardial infarction (r = 0.86 and r = 0.82, respecti vely, both P<0.0001). A reasonable correlation between perfusion and left v entricular ejection fraction was found for the patients with myocardial inf arction (r = 0.41, P = 0.002), and a non-significant correlation for the pa tients without myocardial infarction (r = 0.37, P = 0.1). Quantitative gate d SPET myocardial imaging allows the detection of residual wall thickening in patients with a previous myocardial infarction who show severe fixed per fusion defects. In patients without myocardial infarction, gated SPET imagi ng allows differentiation between an attenuation artefact and a fixed perfu sion defect due to coronary artery disease. In addition, gated SPET may sho w diminished ventricular function in normally perfused segments possibly du e to myocardial stunning. The addition of gated SPET myocardial perfusion i maging increases diagnostic confidence and may have direct clinical implica tions for optimal patient management. ((C) 2001 Lippincott Williams & Wilki ns).