Comparison of Baseline–Nitrate Technetium-99m Sestamibi With Rest–Redistribution Thallium-201 Tomography in Detecting Viable Hibernating Myocardium and Predicting Postrevascularization Recovery

Objectives. This study aimed to define the optimal criteri for detecting viable myocardium with rest–redistribution thallium-201 (Tl-201) or baseline–nitrate technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) using discriminant analysis and to compare the accuracy of the two tracers in predicting postrevascularization recovery. Background. Rest–redistribution Tl-201 imaging is currently used for detection of myocardial viability, but the optimal variables for territory classification have not yet been defined. Although Tc-99m sestamibi is reportedly less effective than Tl-201, its reliability can be increased by injecting it during nitrate infusion. Methods. In 35 patients with left ventricular (LV) dysfunction, tracer activity within asynergic coronary territories was quantified on rest and redistribution Tl-201 and baseline and nitrate Tc-99m sestamibi SPECT. Asynergic territory viability was evaluated on the basis of the postrevascularization functional outcome. Results. Percent activity within asynergic territories was significantly influenced by their viability (p < 0.005) and the type of acquisition (p < 0.0001) but not by the tracer used. Discriminant analysis identified redistribution Tl-201 activity and nitrate-induced Tc-99m sestamibi activity change as the two most significant predictors of postrevascularization recovery. The discriminant function defined for Tl-201, including redistribution activity and reversibility, correctly classified 38 of 56 asynergic territories, whereas that for Tc-99m sestamibi, including nitrate-induced activity change and activity in nitrate images, correctly classified 43 territories. Conclusions. Redistribution activity is more important than reversibility when differentiating viable from nonviable territories using rest–redistribution Tl-201. In Tc-99m sestamibi SPECT, nitrate-induced activity changes are particularly useful in identifying myocardial viability. Baseline–nitrate Tc-99m sestamibi SPECT appears no less effective than rest–redistribution Tl-201 in predicting postrevascularization recovery.