Identification of Coronary Thrombus With a IIb/IIIa Platelet Inhibitor Radiopharmaceutical, Technetium-99m DMP-444 A Canine Model

Background—A diagnostic test that could distinguish between stable and unstable coronary atherosclerotic plaques would be useful. We tested the ability of a new glycoprotein IIb/IIIa platelet inhibitor DMP-444, labeled with technetium (Tc)-99 m, to identify platelet-rich thrombus by nuclear imaging in a canine model. Methods and Results—Combinations of a flow-limiting stenosis and 0 to 15 minutes of endothelial electrical stimulation at a site in the left anterior descending coronary artery were used to induce varying amounts of thrombus formation. In 10 animals with markedly positive nuclear images after the injection of Tc-99m DMP-444, the presence of platelet-rich thrombus was confirmed postmortem by gross appearance, high nuclear counts, and abundant platelets on electron microscopy. The 10 animals with negative images had lower counts, smaller thrombus weights (P<0.05 for each), and fewer platelets by electron microscopy. Conclusions—Activated platelets participating in acute thrombus formation can b...