Effect of E5510, a novel antiplatelet agent, on platelet deposition in atherothrombotic lesions: evaluation by 111In platelet scintigraphy.

We evaluated the short-term effects of a novel antiplatelet agent, 4-cyano-5,5-bis(methoxyphenyl)-4-pentenoic acid (E5510), using 111In platelet scintigraphy (PSG) and B-mode ultrasonography (US). Fifteen patients with platelet deposition at either the carotid bifurcation or abdominal aorta on PSG were randomized into two groups: seven were followed without anti-thrombotic medication (Group A) and eight received E5510 (4 mg x day(-1)) (Group B). After 8 weeks, PSG and US were repeated in all patients. Platelet deposition was assessed visually and semi-quantitatively using a platelet accumulation index. Visual analysis showed that seven out of eight patients became negative for platelet deposition after treatment in Group B, while none changed in Group A. The platelet accumulation index of vessels with platelet deposition was significantly reduced after treatment in Group B (12.4+/-3.9% vs 6.0+/-7.1%, p <0.01), while there was no significant change in the vessels without platelet deposition (2.9+/-3.0% vs 2.9+/-4.1%). In Group A, none of the vessels showed any change (8.1+/-6.4% vs 8.9+/-7.3%). However, there was no significant reduction of carotid plaque size in either group. Short-term E5510 therapy inhibited platelet deposition in active atherothrombotic lesions, and the combination of PSG and US was useful for evaluating the effectiveness of anti-thrombotic drugs in vivo.