Investigation of the Clinical Efficacy of (TC)-T-99m-Sestamibi Washout in Patients with Acute Myocardial Infarction and Comparison with Stress Myocardial Imaging with Tc-99m-Sestamibi Using a Two-Day Protocol

Background: Tc-99m-sestamibi myocardial perfusion imaging (MIBI) washout is associated with myocardial mitochondrial damage in patients with a successful percutaneous coronary intervention (PCI) following acute myocardial infarction (AMI) and may predict the functional improvement of the left ventricle in follow-ups. Objectives: This study aimed to investigate the clinical efficacy of Tc-99m-MIBI washout in patients with AMI by measuring the mean defect area based on Tc-99m-MIBI myocardial perfusion-single photon emission computed tomography (MP-SPECT) rest imaging in early and delayed phases and comparing it with the defect area based on Tc-99m-MIBI MP-SPECT adenosine stress imaging based on a two-day rest/stress protocol. Patients and Methods: This study was conducted on 29 consecutive patients with AMI (23 males and 6 females; mean age, 71 +/- 8.4 years), who underwent MP-SPECT using a standard two-day rest/stress protocol. The rest Tc-99m-MIBI MP-SPECT images were acquired in the earlyphase at one hour after the injection of Tc-99m-MIBI and in the delayed phase at three hours after the early phase. The total perfusion deficit (TPD) score for SPECT was measured to compare the defect area between the rest-early phase, rest-delayed phase, and post-stress imaging conditions. Results: Based on the results, the post-stress TPD score was significantly lower than the rest-delayed phase score (TPD: 22.2% +/- 14.3% vs. 27.8% +/- 14.0%; P < 0.001). Also, the rest-early phase score was significantly lower than the rest-delayed phase score (TPD: 21.5% +/- 14.9% vs. 27.8% +/- 14.0%; P < 0.001). However, no significant difference was observed between the post-stress score and the rest-early phase score. Conclusion: The combination of rest-early phase, delayed phase, and post-stress Tc-99m-MIBI imaging using a two-day protocol after AMI reperfusion was a clinically useful method, which could identify residual ischemia and predict the left ventricular function improvement in the chronic phase of disease while reducing the exposure dose.