Abstract 2633: Coated-Platelet Levels are Elevated in Symptomatic Carotid Stenosis Patients and Associated with Stroke Recurrence

Abstract

Background: Coated-platelets are a subset of platelets with high procoagulant potential observed upon dual agonist stimulation with collagen and thrombin. Coated-platelet levels, expressed as percentages of the total platelet population, are elevated in patients with non-lacunar ischemic stroke and decreased in patients with spontaneous intracerebral hemorrhage compared to controls. Because of these findings, we investigated whether coated-platelets are elevated in patients with symptomatic carotid stenosis compared to controls and if there is an association between coated-platelet levels and stroke recurrence among subjects with carotid stenosis. Methods: Coated-platelet levels were determined in 40 consecutive patients with acute stroke due to ipsilateral high-grade internal carotid artery stenosis and 60 gender-frequency-matched controls without history of stroke. The neurologist establishing the diagnosis was unaware of the patient's coated-platelet levels, and the individuals performing the coated-platelet assay were not aware of the clinical diagnosis. Stroke recurrence data were obtained through stroke clinic visits or telephone interviews performed at 1month following the initial infarct. The distribution of baseline characteristics was compared between patients and controls using either a t-test for continuous measures or a Chi-square test (or Fisher’s exact test) for categorical measures. Linear regression models were fit to explore the association between carotid stenosis status and coated-platelet levels with and without adjustment for confounding factors. Percentages of subjects who developed a recurrent stroke at one month were compared using Fisher’s exact test. Results: Coated-platelet levels (mean±SD) were significantly higher in patients with symptomatic carotid stenosis compared to controls (41.3±15.5% vs. 30.1±13.4%, p=0.0002). The estimated difference remained significant after adjustment for demographics, medication use and co-morbidities (p=0.0003). Among the 40 carotid stenosis patients, the cumulative incidence of recurrent stroke at 1 month was 18% (95% CI:9-34%, 7 recurrences). Patients were then analyzed according to quartiles of coated-platelet levels (split at ≤32%, 32.1-42.4%, 42.5-51%, >51%). The 1-month stroke recurrence percentages differed significantly between the coated-platelet quartiles (p=0.041), with 50% recurrence percentage (n=5) among patients in the highest quartile compared to 10% among those in the first (n=1) and third (n=1) quartiles and 0% among those in the second quartile. Conclusions: Coated-platelet levels are higher in patients with symptomatic high-grade carotid stenosis compared to controls and are associated with early stroke recurrence in this patient population. Additional study of coated-platelets in carotid stenosis is warranted.