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.
OBJECTIVE
The value of 99mTc-sestamibi (2-methoxy-isobutyl isonitrile [MIBI]) as a 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 a severely stenosed left anterior descending coronary artery and wall motion abnormalities were prospectively included. The patients underwent a MIBI rest study, a positron emission tomographic (PET) flow (13NH3) and metabolism (18F-deoxyglucose) study and nuclear angiography before undergoing bypass surgery. A 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). A 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, a 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. A linear relation was found between percent fibrosis and MIBI uptake. An optimal threshold of 50% was found for prediction of functional recovery.
Maes
A F
AF
Department of Nuclear Medicine, K. U. Leuven, Belgium.
Borgers
M
M
Flameng
W
W
Nuyts
J L
JL
van de Werf
F
F
Ausma
J J
JJ
Sergeant
P
P
Mortelmans
L A
LA
D000641:Ammonia; D017023:Coronary Angiography; D001026:Coronary Artery Bypass; D003327:Coronary Disease / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D003847:Deoxyglucose / Q000031:analogs & derivatives; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D015637:Gated Blood-Pool Imaging; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D009206:Myocardium / Q000473:pathology; D009590:Nitrogen Radioisotopes; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D017256:Technetium Tc 99m Sestamibi; D014055:Tomography, Emission-Computed; D015899:Tomography, Emission-Computed, Single-Photon
D005462:Fluorine Radioisotopes; D009590:Nitrogen Radioisotopes; D019788:Fluorodeoxyglucose F18; D000641:Ammonia; D017256:Technetium Tc 99m Sestamibi; D003847:Deoxyglucose