MYOCARDIAL PERFUSION SCINTIGRAPHY IN HEART-TRANSPLANT RECIPIENTS WITHAND WITHOUT ALLOGRAFT ATHEROSCLEROSIS - A COMPARISON OF TL-201 AND TC-99M SESTAMIBI

Our objectives were to assess the comparative value of thallium-201 an d technetium 99m sestamibi for the detection of cardiac allograft athe rosclerosis and the left ventricular ejection fraction response to exe rcise in heart transplant recipients with and without allograft athero sclerosis. Allograft atherosclerosis is the critical factor limiting l ong-term survival in heart transplant recipients. Annual coronary angi ography is invasive and expensive. A noninvasive test to detect allogr aft atherosclerosis would be clinically useful. Treadmill exercise tes ting followed by myocardial perfusion single-photon computed tomograph ic imaging was performed in 25 heart transplant recipients. All patien ts underwent coronary angiography. Group 1 (13 patients) had angiograp hic coronary artery disease; group 2 (12 patients) did not. Eighteen p atients underwent two exercise tests to equivalent work loads with tha llium-201 and technetium 99m sestamibi; seven patients underwent only thallium-201 imaging. First-pass left ventricular ejection fraction wa s measured during injection of technetium 99m sestamibi. In group 1, 1 0 of 13 patients had abnormal thallium-201 scans. There was no signifi cant difference in the number of patients who had abnormal thallium-20 1 (7/10) and technetium 99m sestamibi scans (6/10). Fifty-two percent (12/23) of discordantly scored segments were reversible on thallium-20 1 and fixed on technetium 99m sestamibi imaging compared with the oppo site (0%; 0/23) (p < 0.01). All patients in group 2 had normal perfusi on scans. There were no false-positive scans. There was no significant difference in resting and exercise first-pass ejection fractions or i n the ejection fraction response to exercise between the two groups: g roup 1, resting 60 +/- 10 and exercise 66 +/- 7; group 2, resting 52 /- 8 and exercise 63 +/- 12.