Summary
Patients with carotid atheromatous lesions were prospectively studied with indium-111 platelet imaging, platelet aggregability and B-mode real-time ultrasound tests to determine the shortterm effects of orally active prostacyclin analogue TRK-100 (40 μg, three times daily for 4 weeks). To establish baseline values, all patients underwent indium-111 platelet imaging, platelet aggregation study and B-mode ultrasound. The results were positive for carotid plaque and platelet accumulation. Visual analysis showed repeated platelet scintigrams to be unchanged in five patients without antithrombotic therapy; repeated ultrasound studies showed no change in eight of ten plaques, while one showed progression and one regression of the plaque. In five TRK-100 treated patients, five of seven lesions with platelet accumulation at the baseline became negative, and two remained unchanged during the treatment; repeated B-mode ultrasound tests indicated eight of nine plaques remained unchanged, while one showed plaque size reduction. Quantitative analysis demonstrated that, TRK-L00 significantly reduced the ADP aggregation (1 μM) from 55.2 ± 21.3"/" to 24.0 ± 14.7% (± Sp; p <0.05) and the platelet accumulation index (25.7 ± 17.2% vs L0.4 ± 10.4%; p <0.05). However, there was no significant reduction in plaque scores during TRK-100 therapy compared with the baseline (2.70 ± 2.75 mm vs 2.51 ± 2.58 mm). The data obtained suggested that short-tenn TRK-L00 therapy has an inhibitory effect on platelet accumulation in carotid atheroma but does not cause significant changes in plaque size.
