Abstract
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Objectives Accelerated clearance of Tc-99m sestamibi (MIBI) has been observed after reperfusion therapy in acute coronary syndrome (ACS) but the mechanisms have not been fully investigated. The purpose was to examine the association between accelerated MIBI clearance and oxidative metabolism estimated by C-11 acetate PET in patients with ACS.
Methods Eighteen patients (10 men, 69.2±8.7 years old) with reperfused ACS underwent rest MIBI SPECT, echocardiography and acetate PET within 3 weeks after onset of ACS. MIBI images were obtained 30 minutes and 3 hours after MIBI injection. Accelerated MIBI clearance was defined as decrease of 1 or more segmental defect score by visual analysis. Regional left ventricular function was evaluated by echocardiography. Oxidative metabolism was obtained by the mono-exponential fit of the C-11 acetate time-activity curve (kmono).
Results Among reperfused segments, MIBI SPECT showed 64 normal segments (Group N), 14 segments with accelerated MIBI clearance (Group AC) and 17 segments with fixed perfusion defect (Group F). LV wall motion score was lower in both Group AC (2.29±0.99 vs. 1.47±0.62, P=0.003) and F (2.41±1.06 vs. 1.47±0.62, P<0.001) compared with Group N. However, LV wall motion improved in Group AC (P=0.015) but unchanged in Group F (P=0.77) at follow-up period. Oxidative metabolism decreased in Group AC (0.0407±0.0088 vs. 0.0487±0.0099, P=0.042) and Group F (0.0391±0.0116 vs. 0.0487±0.0099, P=0.005) compared with Group N.
Conclusions Segments with accelerated MIBI clearance showed reduced oxidative metabolism but improved regional LV function after revascularization in the patients with ACS.
Research Support This study was partly supported by FUJI FILM Pharma, Co, Ltd.