Comparison of the myocardial perfusion and wall motion results by ECG-Gated 99mTc-MIBI SPECT, before and after CABG for evaluation of myocardial viability]

It is of value to determine the amount of viable myocardial tissue in patients suffering from chronic coronary artery disease and ventricular dysfunction. Having the capability of evaluating both myocardial perfusion and function, simultaneously, myocardial scanning by ECG-Gated is an appropriate method for this purpose. The aim of this study was to compare the results of myocardial perfusion and wall motion before and after Coronary Artery Bypass Grafting (CABG), as well as assessment of the efficiency of these parameters for detection of myocardial viability. Forty patients with positive history of previous myocardial infarction and candidate for CABG underwent ECG-Gated SPECT scanning 1 month before and 2-3 months after surgery. Findings of myocardial perfusion and wall motion, obtained from the two phases of the study, were compared. The results showed that functional status of some preoperatively severely hypoperfused segments, recovered significantly after CABG, which proved existence of viable tissue in these regions. Also, septal wall motion presented no statistically significant changes after CABG. These results suggest that septal perfusion and motion are not reliable parameters for the assessment of surgical outcome in this region. Most of the myocardial walls demonstrated considerable wall motion improvement after operation. Concerning the results of this research, as a marker of viable against nonviable myocardial tissue, we recommend revision of applying the severity of perfusion defect, alone, as well as taking the wall motion parameter into consideration, to improve diagnostic accuracy of the SPECT method.