No abstract

In patients with coronary artery disease who have LV dysfunction, nitrate-enhanced sestamibi gated SPECT allows a reliable WM evaluation, both at rest and during LDD infusion, in almost all segments and provides results in agreement with LDDE.

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 technetium99m 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.

Injection of sestamibi during low-dose dobutamine (LDD) infusion might improve tracer ability to detect viable myocardium. This study investigated the potential value of LDD technetium-99m sestamibi (sestamibi) single-photon emission computed tomography (SPECT) in predicting functional recovery after revascularization by comparing its results with those of sestamibi SPECT at rest and of LDD echocardiography. Before revascularization, 23 patients with chronic coronary artery disease and regional left ventricular dysfunction underwent sestamibi SPECT at rest and, on a separate day, LDD echocardiography and sestamibi SPECT with tracer injection during LDD infusion. Echocardiography at rest was repeated after revascularization. Semiquantitative sestamibi uptake results (grading from 0 ‫؍‬ normal to 4 ‫؍‬ absent) and wall motion (grading from 1 ‫؍‬ normal to 4 ‫؍‬ dyskinesia) were evaluated with a 16-segment model. The ventricular wall was divided into 3 vascular territories. At follow-up, 20 of 32 asynergic vascular territories showed functional recovery, whereas 12 showed no changes. For prediction of functional recovery, LDD SPECT achieved better accuracy than SPECT at rest (87% vs 65%, p <0.05); positive and negative predictive values of LDD SPECT were 90% and 83%, respectively, which was not significantly different from the related LDD echocardiographic values (84% and 69%). Thus, LDD sestamibi SPECT appears to be a promising method for detecting myocardial viability, which provides better accuracy than sestamibi SPECT at rest, and achieves predictive values comparable to those of LDD echocardiography. ᮊ2000 by Excerpta Medica, Inc.(Am J Cardiol 2000;86:153-157) T he reliability of technetium-99m sestamibi (sestamibi) scintigraphy for the evaluation of myocardial viability is controversial. Uptake correlates with the extent of viable myocardium, 1,2 but sestamibi scintigraphy at rest seems to underestimate myocardial viability compared with thallium-201 scintigraphy or positron emission tomography, 3,4 and shows just a fair agreement with low-dose dobutamine (LDD) echocardiography. 5-7 However, delayed imaging, 8 quantitative analysis of single-photon emission computed tomography (SPECT), 9 or tracer injection under nitrate administration 10,11 improve sestamibi recognition of viable myocardium. Because injection during LDD infusion increases sestamibi uptake in recent infarction, 12 this approach has been suggested to improve viability detection. 13 The aim of the present study was (1) to investigate the ability of baseline and LDD sestamibi SPECT to predict recovery of regional ventricular function after revascularization in patients with chronic coronary artery disease and left ventricular dysfunction, and (2) to compare sestamibi SPECT results with those of LDD echocardiography. METHODSPatient population: We prospectively enrolled 31 consecutive patients with coronary artery disease scheduled for revascularization based on the independent judgment of the referring physician. Sestamibi SPECT and LDD echocardi...

Regional dysfunction assessment directly on perfusion images permits use of different activity thresholds with an improvement over a single cutoff for all asynergic segments. Therefore combining perfusion and functional data with nitrate-enhanced gated SPECT at rest appears to be a promising approach for viability detection.