TC-99M ANTIMYOSIN ANTIBODY (3-48) MYOCARDIAL IMAGING - HUMAN BIODISTRIBUTION, SAFETY AND CLINICAL-RESULTS IN DETECTION OF ACUTE MYOCARDIAL-INFARCTION

Technetium-99m antimyosin (Tc-99m-AM) antibody imaging may have signif icant advantages over indium-111 antimyosin in clinical practice. The purpose of this study was to determine the human biodistribution, the safety profile and the sensitivity of Tc-99m-AM (3-48) imaging in the detection of both Q-wave and non-Q-wave myocardial infarction (MI). Bi odistribution and safety parameters were mainly determined in 12 norma l healthy volunteers while 40 patients with proven MI (22 Q-wave, 18 n on-Q-wave) were injected with Tc-99m-AM (20-25 mCi) between 5 h and 7 days after the onset of acute chest pain. Three standard planar views were performed at 6 h and at 24 h post injection. Both sets of images were completed in 33 patients while two patients were imaged only at 6 h, three patients only at 18 h and one at 18 and 24 h. One patient wa s not imaged. Vital signs and ECG were recorded and blood samples for haematology, biochemistry and human antimurine antibodies (HAMA) and u rinalysis were obtained in all volunteers and patients. No serious adv erse reactions or side-effects attributable to Tc-99m-AM have been rep orted. No volunteers or patients developed allergic reactions or signi ficant increases in HAMA titres. Reading of Tc-99m-AM imaging was perf ormed by two blinded experienced observers. The sensitivity of Tc-99m- AM in the detection of MI was 100% (21/21) for Q-wave and 83.3% (15/18 ) for non-Q-wave infarctions. The overall sensitivity was 92.3% (36/39 ). The three false-negative cases were inferoposterior MI. A certain d egree of uptake focalization was seen in 26 out of 35 (74.2%) at 6 h. At 24 h, two patients (5.8%) did not show Tc-99m-AM uptake while 22 (6 4.7%) showed intense focal uptake, seven (20.6%) moderate uptake and 3 (8.9%) slight uptake. It is concluded that Tc-99m-AM (3-48) imaging i s safe and shows high sensitivity in the detection of both Q-wave and non-Q-wave MI even with early imaging (6 h post injection). These prom ising results warrant further clinical investigation.