Increased Platelet Count and Lymphocyte-Platelet Complex Formation in Patients with Recently Symptomatic Versus Asymptomatic Carotid Stenosis: Results from the Platelets and Carotid Stenosis (PACS) Study (P01.026)

Abstract

Objective: We hypothesised that patients with recently symptomatic moderate or severe carotid stenosis would have excessive platelet activation compared with asymptomatic carotid stenosis patients. Background The precise mechanisms responsible for the disparity in stroke risk between asymptomatic and symptomatic carotid stenosis patients are unclear. We hypothesised that recently symptomatic patients would have excessive platelet activation compared with their asymptomatic counterparts. Design/Methods: We performed an observational analytical study to compare haematological parameters and platelet activation status in asymptomatic versus early (≤4 weeks after TIA or stroke onset) and late phase (≥3 months) symptomatic moderate or severe (≥50%) carotid stenosis patients. The sensitive and specific technique of whole blood flow cytometry was used to quantify platelet surface CD62P and CD63 expression, and the % circulating leucocyte-platelet complexes. Unpaired non-parametric comparisons were performed with the Wilcoxon rank sum test. Results: Data from 31 asymptomatic carotid stenosis patients were compared with those from 46 symptomatic patients in the early phase, and 35 of these patients in the late phase after symptom onset, 23 of whom underwent intervention. Median platelet count was higher in early symptomatic than asymptomatic carotid stenosis patients (211 vs. 200 x 109/L; p=0.03), but the differences between the late symptomatic and asymptomatic groups were not significant (219 vs 200 x 109/L, p=0.1). The median % lymphocyte-platelet complexes was higher in early symptomatic than asymptomatic patients (2.8 vs. 2.4%, p=0.001; Figure 1). There were no significant differences in the expression of other activation markers between the groups. Conclusions: These findings improve our understanding of the haemostatic/thrombotic profile in carotid stenosis. Increased platelet count and leucocyte-platelet complex formation could predispose to recurrent ischaemia or infarction in patients with recently symptomatic carotid stenosis. Longitudinal studies are warranted to assess the prognostic value of these biomarkers in asymptomatic and symptomatic carotid stenosis. Disclosure: Dr. Kinsella has nothing to disclose. Dr. Tobin has nothing to disclose. Dr. Tierney has nothing to disclose. Dr. Feeley has nothing to disclose. Dr. Egan has nothing to disclose. Dr. Collins has nothing to disclose. Dr. Coughlan has nothing to disclose. Dr. O9Neill has nothing to disclose. Dr. Harbison has nothing to disclose. Dr. Doherty has received personal compensation for activities with UCB Pharamaceuticals, Eiasi, and Jansen-Cilag. Dr. Madhavan has nothing to disclose. Dr. Moore has nothing to disclose. Dr. O9Neill has nothing to disclose. Dr. Murphy has nothing to disclose. Dr. Hamilton has nothing to disclose. Dr. Mccabe has nothing to disclose.