Prediction of functional recovery in patients with chronic coronary artery disease and left ventricular dysfunction combining the evaluation of myocardial perfusion and of contractile reserve using nitrate-enhanced technetium-99m sestamibi gated single-photon emission computed tomography and Dobutamine stress

This study aimed to assess whether contractile reserve evaluation using dobutamine gated single-photon emission computed tomography (SPECT) improves the capability of quantitative perfusion analysis to predict functional recovery of viable hibernating myocardium. Resting and dobutamine nitrate-enhanced technetium-99m sestamibi (sestamibi) gated SPECT studies were performed in patients with coronary artery disease who had left ventricular dysfunction. Tracer activity was quantified, and wall motion and thickening visually scored. Reversible dysfunction was identified with gated SPECT repeated after coronary revascularization. Using the best activity threshold, perfusion quantification achieved 85% sensitivity and 55% specificity. Contractile reserve detection was significantly less sensitive (64%, p <0.0005), but more specific (88%, p <0.00001) than perfusion quantification. However, in the subgroup of hypokinetic segments, the sensitivity of contractile reserve assessment was just slightly lower than perfusion quantification (72% vs 91%, p = NS), whereas specificity was significantly higher (94% vs 23%, p <0.00001). Conversely, in the adyskinetic segments, perfusion quantification was significantly more sensitive than contractile reserve (82% vs 59%, p <0.005), but similarly specific (76% vs 85%, p = NS). Therefore, the identification of reversible dysfunction based on perfusion quantification in adyskinetic segments and on contractile reserve detection in hypokinetic segments was significantly more specific (83% vs 55%, p <0.00001) than standard quantitative perfusion SPECT, without major loss in sensitivity (78% vs 85%, p = NS). In conclusion, contractile reserve evaluation using dobutamine gated SPECT enhances the reliability of nitrate-enhanced sestamibi SPECT when used to predict reversible dysfunction in hypokinetic segments, whereas perfusion quantification remains superior in adyskinetic segments.