title: Higher levels of coated-platelets are observed in patients with subarachnoid hemorrhage but lower levels are associated with increased mortality at 30 days.
abstract: BACKGROUND
  Coated-platelets are procoagulant platelets observed upon dual agonist stimulation with collagen and thrombin. Coated-platelet levels are elevated in non-lacunar ischemic stroke compared to either lacunar stroke or controls. In contrast, coated-platelet levels are decreased in spontaneous intracerebral hemorrhage (ICH) and inversely correlated with bleed size. We now report the first investigation of coated-platelets in patients with subarachnoid hemorrhage (SAH).
  
  
  METHODS
  Coated-platelet levels were determined in 40 consecutive patients with spontaneous SAH and in 40 controls. Results are reported as percent of cells converted to coated-platelets. Mortality at one month was recorded for all patients.
  
  
  RESULTS
  Coated-platelet levels (mean ± SD) were significantly higher in SAH patients compared to controls (41.8 ± 11.4% vs. 30.7 ± 12.2%, p<0.0001). Among all patients, mortality at 1 month was 20% (8 deaths). Patients were analyzed according to tertiles of coated-platelet levels (split at <36.7%, 36.7-46.2%, >46.2%). The 1-month mortality differed significantly between the coated-platelet tertiles (p=0.01) with 46% mortality (6/13) among patients in the lowest tertile (lowest levels) compared to 14.3% (2/14) among those in the middle tertile and 0% in the highest tertile.
  
  
  CONCLUSIONS
  Coated-platelet levels are higher in SAH patients compared to controls. However, lower coated-platelet levels are associated with increased 1-month mortality in SAH patients, a finding compatible with prior observations of an inverse relationship between coated-platelet levels and bleed volume in ICH. The current data support the role played by these prothrombotic platelets in thrombosis or hemorrhage and suggest a potential place for coated-platelet levels in predicting prognosis after SAH.
authors.affiliation: Department of Neurology, University of Oklahoma Health Sciences Center, Oklahoma City, USA; Veterans Affairs Medical Center, Oklahoma City, OK, USA. Electronic address: calin-prodan@ouhsc.edu.
authors.forename: Calin I
authors.initials: CI
authors.lastname: Prodan
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Vincent
authors.forename: Angelia C
authors.initials: AC
authors.lastname: Kirkpatrick
authors.forename: Steven L
authors.initials: SL
authors.lastname: Hoover
authors.forename: George L
authors.initials: GL
authors.lastname: Dale
mesh_terms: D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D012307:Risk Factors; D013345:Subarachnoid Hemorrhage / Q000097:blood* / Q000401:mortality*; D013997:Time Factors
keywords: Hemostasis; Ischemia; Platelets; Stroke; Subarachnoid hemorrhage; Thrombosis