Diagnostic and Prognostic Value of Gated SPECT MIBI Early Post-Stress Imaging in Patients With Intermediate Duke Treadmill Score

Purpose of the Report: The aims of this study were to compare perfusion and functional parameters between early (ES) and standard (SS) post-stress gated SPECT MIBI, to validate ES against coronary angiography, and to determine whether ES parameters can predict future cardiac events. Patients and Methods: The sample included 63 patients with normal or mildly impaired left ventricular function and intermediate Duke Treadmill Score. They underwent a 2-day stress-rest gated SPECT MIBI with the poststress data acquired at 15 minutes (ES) and 60 minutes (SS) after i. v. injection of 740 MBq of Tc-99m-MIBI. The ES findings were compared to SS and against coronary angiography to determine their sensitivity/specificity for detecting >70% stenosis. The information about new-onset cardiac events was collected 26 +/- 6 months later. Results: Perfusion parameters did not significantly differ between ES and SS. Ejection fraction was significantly lower and regional wall motion abnormalities were significantly higher on ES than SS. The corresponding perfusion and functional parameters were strongly related (linear regression slope 0.65-1.00, intercept -0.36-8.5, R-2 0.98-0.75). ES parameters had high sensitivity (96%) and specificity (83%) for detecting >70% stenosis. Lower early stress than rest EF (>5%), higher early stress than rest EDV, and early SSS >8 emerged as significant predictors of new-onset cardiac events. Conclusions: Early post-stress gated SPECT MIBI yields comparable perfusion and functional parameters as the standard post-stress protocol. ES parameters are useful for detecting the existing coronary disease and for predicting future cardiac events. ES protocol is recommended for improving patient compliance and efficiency of nuclear cardiology services.