257 Prevalence of aspirin resistance in stable coronary heart diseased patients and correlation with platelet turn-over

Background Aspirin resistance has been widely reported but the underlying mechanisms remain unclear. Previous studies have suggested a relationship between accelerated platelet turn-over and aspirin resistance in patients with coronary artery disease. The purpose of this study was to determine whether aspirin resistance could be linked to accelerated platetet turn-over. Methods We performed a prospective monocentric study including 50 consecutive patients with stable coronary artery disease treated by aspirin (75 to 250 mg/day) without any other antiaggregant treatment. Aspirin resistance was characterized 24 hours after aspirin intake by light transmission aggregometry using 0.5 mg/mL arachidonic acid. Aspirin resistance was defined as >20% residual agregation. Platelet turn-over was estimated at the same time by measurement of mean platelet volume, % of reticulated platelets, serum P-selectin, platelet P-selectin and serum thrombopoietin. Results Among 50 patients (70 ± 11 y.o. mean ± 1,5, 76% male, 52% type 2 diabetes mellitus, 16% active smokers), 18 (36%) were identified as aspirin resistants. Table 1 shows the mean value of markers currently linked to platelet turn-over depending on the presence of aspirin resistance. Serum thrombopoietin was significantly increased in patients with aspirin resistance compared to patients with no aspirin resistance. No statistical difference was demonstrated for mean platelet volume, reticulated platelets, platelet P-selectin and serum P-selectin. Serum thrombopoietin values were not correlated with other platelet turn-over parameters. There was no significant correlation between serum thrombopoietin and inflammatory markers. Conclusion Serum thrombopoietin is associated with aspirin resistance, but no other parameters currently linked to platelet turn-over. Further studies are needed to determine whether serum thrombopoietin can predict aspirin resistance in a larger cohort. Aspirin sensitive Aspirin resistant p Platelet volume (fl) 8.78 ± 0.26 8.82 ± 0.30 0.92 Reticulated platelet (%) 8.4 ± 0.52 8.6 ± 0.76 0.82 Serup P selectin (ng/ml) 42.6 ± 4.29 42.9 ± 4.75 0.97 Platelet P selectin (%) 11.1 ± 1.0 9.5 ± 1.5 0.35 Serum thrombopoietin (pg/ml) 130.6 ± 11.3 319.9 ± 97.8 0.01