Abstract 478: Unchanged Platelet Response during 50mg Acetylsalicylic Acid (ASA) in Coronary Heart Disease (CHD)- an 8 Years Follow-up
ASA significantly reduces atherothrombotic events. Despite ASA-treatment 10 - 20 % of CHD-patients experience clinical events. Several reports claim progressive loss of ASA-antiplatelet capacity, claiming ASA-resistance. We are continuously monitoring 100 patients (37 - 71 years, 60 m, 40 f) who after newly diagnosed CHD (scintigraphy, angiography) were treated with 50 mg ASA (Thrombo ASS, Lannacher, Austria). No other antiplatelet drug was taken. Compliance was assessed by interview, pill counting and determination of serum thromboxane B2. We are reporting the 8-years follow-up data. Platelet function (ADP-, collagen-, epinephrine-induced aggregation, β-thromboglobulin, thromboxane B2, platelet sensitivity against PGI2) was measured before initiation of ASA therapy as well as after 1 week, 1, 3, 6 and 12 months, and thereafter annually. Quintile distribution was assessed. Mortality (n = 7) and vascular events (n = 12) were not associated with a more activated platelet function in any of the tests performed. Only one patient (58 a, f, suffering from MI) after 32 months showed platelet function in the 4th and 5th quintile. Quintile distribution did not significantly change in total patient population nor was there an activation in any of the platelet function parameters before the event. The last follow-up before the event exhibited, however, a significant increase in CRP (0,91±0,36 to 3,21±1,16; p < 0,01 and the adhesion molecule VCAM (608,5±56,4 to 694,7±61,0; p < 0,01). This increase was more pronounced (p < 0,01) in fatal vs. non-fatal events. A parallel increase in blood sedimentation rate was seen too. Number of patients who smoked and those with a higher risk profile were more frequently found in quintiles III - V. Our data provide no evidence for an altered platelet response during 8-years therapy with 50 mg ASA / d.