PREDICTING RECOVERY OF SEVERE REGIONAL VENTRICULAR DYSFUNCTION - COMPARISON OF RESTING SCINTIGRAPHY WITH TL-201 AND TC-99M-SESTAMIBI

Background Regional Tl-201 activity after resting injection, imaged ea rly and after redistribution, reflects viable myocardium and can predi ct improved isotope uptake as well as regional and global ventricular function after revascularization. Tc-99m-sestamibi, a perfusion tracer with favorable imaging characteristics, has distinct kinetics compare d with Tl-201 demonstrating minimal redistribution; this property may give Tl-201 an advantage for detecting viable myocardium, particularly in segments with resting hypoperfusion. The purpose of this study was to compare regional activities of Tl-201 and Tc-99m-sestamibi after r esting injections in patients with coronary artery disease and regiona l or global left ventricular dysfunction and to assess their comparati ve abilities for predicting recovery of severe regional ventricular dy sfunction after revascularization. Methods and Results Qualitative and quantitative comparisons of rest and redistribution Tl-201 activity a nd sestamibi activity 1 hour after rest injection were performed in 31 patients with coronary artery disease and left ventricular dysfunctio n. Quantitative analysis of three short-axis tomograms per patient was performed by use of circumferential profiles that allowed analysis of 12 segments per patient. Two-dimensional echocardiography was used to assess wall motion and thickening in segments corresponding to the si ngle photon emission computed tomography data. Concordance between reg ional Tl-201 activity at redistribution imaging and regional sestamibi activity by semiquantitative visual analysis demonstrated concordant regional activity in 87% of segments; among discordant segments, no si gnificant skew was seen, indicating enhanced uptake of one agent over the other. Quantitative analysis for all segments showed significant c orrelation (r=.86, P<.001) between quantitative regional Tl-201 redist ribution activity and 1-hour post-rest injection sestamibi activity in individual segments. Eighteen of these patients were revascularized, and echocardiography was repeated 20+/-16 days later; segments exhibit ing significant regional ventricular dysfunction before revascularizat ion were classified as having reversible or irreversible dysfunction o n the basis of the change in wall motion and thickening. Tl-201 and se stamibi regional activities were similar in those segments with revers ible (72+/-11% [percent of peak activity] versus 75+/-9%, respectively , P=NS) as well as irreversible ventricular dysfunction (51+/-11% vers us 50+/-8%, P=NS). Positive (75% versus 80% for Tl-201 and sestamibi, respectively) and negative (92% versus 96%, respectively) predictive v alues for recovery of regional ventricular dysfunction after revascula rization were similar for the two agents. Conclusions In patients with coronary artery disease and left ventricular dysfunction, quantified sestamibi activity 1 hour after rest injection parallels redistributio n Tl-201 activity after a resting injection, suggesting that uptake an d subsequent handling of sestamibi are more complex than can be explai ned by a pure flow tracer with no redistribution. Quantitative analysi s of regional activities of both Tl-201 and sestamibi after resting in jections can differentiate viable from nonviable myocardium, and the t wo agents comparably predict reversibility of significant regional wal l motion abnormalities after revascularization in such patients to a s imilar degree.