Assessment of Myocardial Viability in Chronic Coronary Artery Disease Using Technetium-99m Sestamibi SPECT:: Correlation With Histologic and Positron Emission Tomographic Studies and Functional Follow-Up

Objectives. The value of 99mTc-sestamibi (2-methoxy-isobutyl isonitrile [MIBI]) as viability tracer was investigated in patients undergoing coronary artery bypass graft surgery. Background. Initial studies claim that rest MIBI single-photon emission computed tomographic (SPECT) studies can be used to assess myocardial viability. Methods. Thirty patients with severely stenosed left anterior descending coronary artery and wall motion abnormalities were prospectively included. The patients underwent MIBI rest study, positron emission tomographic (PET) flow (13NH3) and metabolism (18F-deoxyglucose) study and nuclear angiography before undergoing bypass surgery. preoperative transmural biopsy specimen was taken from the left ventricular anterior wall. Morphometry was performed to assess percent fibrosis. After 3 months, radionuclide angiography was repeated. Results. Statistically significant higher MIBI values were found in the group with myocardial viability as assessed by PET than in the group with PET-assessed nonviability (p < 0.01). Significantly higher MIBI values were found in the group with enhanced contractility at 3 months (76 ± 13% vs. 53 ± 22%, p < 0.01). linear relation was found between MIBI uptake and percent fibrosis in the biopsy specimen (r = 0.78, p < 0.00001). When maximizing the threshold for assessment of viability with MIBI by using functional improvement as the reference standard, cutoff value of 50% was found, with positive and negative predictive values of 82% and 78%, respectively. Conclusions. 99mTc MIBI uptake was significantly higher in PET-assessed viable areas and in regions with enhanced contractility at 3 months. linear relation was found between percent fibrosis and MIBI uptake. An optimal threshold of 50% was found for prediction of functional recovery.