COMPARISON OF BASE-LINE-NITRATE TC-99M SESTAMIBI WITH REST-REDISTRIBUTION TL-201 TOMOGRAPHY IN DETECTING VIABLE HIBERNATING MYOCARDIUM AND PREDICTING POSTREVASCULARIZATION RECOVERY

Objectives. This study aimed to define the optimal criteria for detect ing viable myocardium with rest-redistribution thallium-201 (Tl-201) o r baseline-nitrate technetium-99m (Tc-99m) sestamibi single-photon emi ssion computed tomography (SPECT) using discriminant analysis and to c ompare the accuracy of the two tracers in predicting postrevasculariza tion recovery. Background. Rest-redistribution Tl-201 imaging is curre ntly used for detection of myocardial viability, but the optimal varia bles for territory classification have not yet been defined. Although Tc-99m sestamibi is reportedly less effective than Tl-201, its reliabi lity can be increased by injecting it during nitrate infusion. Methods . In 35 patients with left ventricular (LV) dysfunction, tracer activi ty within asynergic coronary territories was quantified on rest and re distribution Tl-201 and baseline and nitrate Tc-99m sestamibi SPECT. A synergic territory viability was evaluated on the basis of the postrev ascularization functional outcome. Results. Percent activity within as ynergic territories was significantly influenced by their viability (p < 0.005) and the type of acquisition (p < 0.0001) but not by the trac er used. Discriminant analysis identified redistribution Tl-201 activi ty and nitrate-induced Tc-99m sestamibi activity change as the two mos t significant predictors of postrevascularization recovery. The discri minant 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 activit y change and activity in nitrate images, correctly classified 43 terri tories. Conclusions. Redistribution activity is more important than re versibility when differentiating viable from nonviable territories usi ng rest-redistribution Tl-201. In Tc-99m sestamibi SPECT, nitrate-indu ced activity changes are particularly useful in identifying myocardial viability. Baseline-nitrate Tc-99m sestamibi SPECT appears no less ef fective than rest-redistribution Tl-201 in predicting postrevasculariz ation recovery. (C) 1997 by the American College of Cardiology.