title: Coated-platelets improve prediction of stroke and transient ischemic attack in asymptomatic internal carotid artery stenosis.
abstract: OBJECTIVE
  Coated-platelets, a subset of procoagulant platelets observed on dual agonist stimulation with collagen and thrombin, support a robust prothrombinase activity and provide a unique measure of platelet thrombotic potential. Coated-platelet levels are increased in large artery stroke, and higher levels are associated with early stroke recurrence, suggesting a potential role for risk stratification in asymptomatic patients with carotid artery stenosis.
  
  
  METHODS
  Three-hundred twenty-nine consecutive patients with technically adequate carotid Doppler evaluation without stroke or transient ischemic attack (TIA) in the previous 6 months were enrolled as part of a prospective cohort study conducted during a 40-month period. The main outcome was occurrence of stroke or TIA according to coated-platelet levels and internal carotid stenosis severity at enrollment. The optimal cutoff value of coated-platelet levels was determined by recursive partitioning analysis. Event-free survival was estimated using Kaplan-Meier and Cox proportional hazards regression analyses.
  
  
  RESULTS
  A cutoff of ≥45% for coated-platelet levels in combination with stenosis≥50% yielded a sensitivity of 0.78 (95% confidence interval, 0.51-1.0), specificity of 0.92 (0.89-0.95), positive predictive value of 0.21 (0.07-0.34), and a negative predictive value of 0.99 (0.98-1.0) for ipsilateral stroke or TIA. The incidence rate of ipsilateral stroke or TIA for patients with ≥50% stenosis and ≥45% coated-platelets was 21.5 per 100 person-years versus 1.27 per 100 person-years for patients with ≥50% stenosis and <45% coated-platelets (P<0.0001).
  
  
  CONCLUSIONS
  Coated-platelet levels identify asymptomatic carotid stenosis patients at high risk for stroke or TIA, which suggests a role for coated-platelets in risk stratification before revascularization.
authors.affiliation: From the Departments of Medicine (A.C.K., A.J.T., G.L.D.) and Neurology (C.I.P.), University of Oklahoma Health Sciences Center, Oklahoma City; Cognitive Science Research Center, University of Oklahoma, Norman (A.S.V.); and Veterans Affairs Medical Center, Oklahoma City, OK (A.C.K., C.I.P.). akirkpat@ouhsc.edu.
authors.forename: Angelia C
authors.initials: AC
authors.lastname: Kirkpatrick
authors.affiliation: From the Departments of Medicine (A.C.K., A.J.T., G.L.D.) and Neurology (C.I.P.), University of Oklahoma Health Sciences Center, Oklahoma City; Cognitive Science Research Center, University of Oklahoma, Norman (A.S.V.); and Veterans Affairs Medical Center, Oklahoma City, OK (A.C.K., C.I.P.).
authors.forename: Alfonso J
authors.initials: AJ
authors.lastname: Tafur
authors.affiliation: From the Departments of Medicine (A.C.K., A.J.T., G.L.D.) and Neurology (C.I.P.), University of Oklahoma Health Sciences Center, Oklahoma City; Cognitive Science Research Center, University of Oklahoma, Norman (A.S.V.); and Veterans Affairs Medical Center, Oklahoma City, OK (A.C.K., C.I.P.).
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Vincent
authors.affiliation: From the Departments of Medicine (A.C.K., A.J.T., G.L.D.) and Neurology (C.I.P.), University of Oklahoma Health Sciences Center, Oklahoma City; Cognitive Science Research Center, University of Oklahoma, Norman (A.S.V.); and Veterans Affairs Medical Center, Oklahoma City, OK (A.C.K., C.I.P.).
authors.forename: George L
authors.initials: GL
authors.lastname: Dale
authors.affiliation: From the Departments of Medicine (A.C.K., A.J.T., G.L.D.) and Neurology (C.I.P.), University of Oklahoma Health Sciences Center, Oklahoma City; Cognitive Science Research Center, University of Oklahoma, Norman (A.S.V.); and Veterans Affairs Medical Center, Oklahoma City, OK (A.C.K., C.I.P.).
authors.forename: Calin I
authors.initials: CI
authors.lastname: Prodan
mesh_terms: D000368:Aged; D001792:Blood Platelets / Q000166:cytology*; D016893:Carotid Stenosis / Q000150:complications*; D015331:Cohort Studies; D005260:Female; D005434:Flow Cytometry; D006403:Hematologic Tests / Q000379:methods; D006801:Humans; D002546:Ischemic Attack, Transient / Q000175:diagnosis* / Q000401:mortality; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012680:Sensitivity and Specificity; D020521:Stroke / Q000175:diagnosis* / Q000401:mortality
keywords: blood platelets; carotid arteries; stroke; thrombosis