Background: This study was designed to clarify the significance of washout rate (WR) determined from 99mTc-sestamibi myocardial scintigraphic images and the levels of cardiac enzymes in patients with acute myocardial infarction (AMI) after percutaneous coronary intervention (PCI).
Material/Methods: A total of 56 consecutive patients with AMI (mean age 65.8±8.5 years), who underwent PCI on admission, were included. Cardiac enzyme, the MB isoenzyme of creatinine kinase (CK-MB), was measured every 3 h after admission. Two weeks after the onset of AMI, 99mTc-sestamibi myocardial scintigraphy was performed at early (30 min) and delayed (4 h) phases after tracer injection. The heart-to-mediastinum ratio (H/M) and WR were calculated from the planar images.
Results: PCI was performed at 9.4±6.0 h after the onset of AMI. In 26 patients the culprit lesion was located in the right coronary artery and in 24 patients it was located in the left anterior descending coronary artery. The peak CK-MB was 274.1±169.4 IU/L (13.5±3.9 h). The early and delayed H/Ms and WR of 99mTc-sestamibi were 2.74±0.58, 3.00±0.70, and 58.8±10.0%, respectively. The delayed H/M was significantly correlated with the peak CK-MB (r=–0.37, p=0.005). The WR of 99mTc-sestamibi was also significantly correlated with the peak CK-MB (r=–0.34, p=0.012).
Conclusions: These results suggest that the WR determined from 99mTc-sestamibi myocardial scintigraphic images reflects the extent of myocardial damage in AMI patients.

Keywords: Myocardial Perfusion Imaging - methods, Myocardial Infarction - radionuclide imaging, Angioplasty, Balloon, Coronary - methods, Myocardium - pathology, Technetium Tc 99m Sestamibi - diagnostic use