Tc-99m-tetrofosmin SPECT for prediction of functional recovery defined by MRI in patients with severe left ventricular dysfunction: Additional value of gated SPECT

This study was designed to evaluate gated Tc-99m-tetrofosmin SPECT for pred iction of functional recovery proven by sequential MRI, Tc-99m-labeled tetr ofosmin is a recently introduced tracer for myocardial perfusion. However, its role for viability assessment is still under investigation. Methods: Tc -99m-tetrofosmin uptake in 19 patients with coronary artery disease and sev ere left ventricular dysfunction was correlated to regional wall thickening before and 4.5 +/- 0.8 mo after successful coronary artery bypass grafting , as derived from corresponding gated short-axis MRI, Preoperative wall thi ckening determined by gated SPECT was used as an additional parameter for p rediction of functional outcome. Optimal threshold cutoffs to separate reve rsible from irreversible dysfunction were determined by receiver operator c haracteristic (ROC) analysis. Results: The sensitivity and specificity of r egional Tc-99m-tetrofosmin for prediction of functional recovery was 87% an d 42%, respectively (cutoff: 50% of maximum tracer retention). The area und er ROC curves for prediction of functional recovery measured 0.66 +/- 0.01. Segments with greater than or equal to 50% uptake and impaired but detecta ble wall thickening determined by gated SPECT had a significantly higher li kelihood for functional improvement compared with segments with absent wall thickening (P < 0.05), There was no difference in segments with <50% trace r retention. There was good agreement for ejection fraction measurements by MRI and gated SPECT (mean ejection fraction 32 +/- 12 versus 34 +/- 11; r = 0.71, P < 0.001). Conclusion: Regional Tc-99m-tetrofosmin uptake provided high sensitivity but limited specificity for prediction of functional reco very after revascularization, leading to fair overall accuracy. Wall thicke ning assessment derived from gated SPECT may improve the specificity of Tc- 99m-tetrofosmin uptake for prediction of functional recovery but not the se nsitivity in low-flow areas, In addition to the assessment of global functi on, gated data acquisition can be helpful to improve the overall accuracy o f Tc-99m-tetrofosmin SPECT for prediction of functional recovery after bypa ss surgery.