title: "Short" thrombelastography as a test of platelet reactivity in response to antiplatelet therapy: validation and reproducibility.
abstract: BACKGROUND
  A significant proportion of patients receiving dual antiplatelet therapy following percutaneous coronary intervention experience recurrent ischaemic events despite standard doses of treatment. Although clinical studies show significant heterogeneity in antiplatelet therapy responses, routine testing is not undertaken due to (i) lack of a standardized test, and (ii) poor clarity with regards to definition of abnormal responses. Short Thrombelastography (s-TEG) is a validated test that allows rapid measurement of clotting responses to antiplatelet therapy.
  
  
  OBJECTIVE
  This study sought to determine the reproducibility of s-TEG and to compare s-TEG with VerifyNow in assessment of responses to antiplatelet therapy.
  
  
  METHODS
  (i) intra-individual variability was assessed using s-TEG Area Under the Curve (AUC15) and maximum amplitude (MA) in one volunteer at 20 time-points on no medication and at 10 time-points pre and post 300 mg aspirin treatment (ii) inter-individual variability was determined from a retrospective analysis of data on MA and AUC15 obtained from 56 volunteers on no medication, 25 volunteers pre and post 300 mg aspirin treatment and 28 patients pre and post 600 mg clopidogrel treatment (iii) a comparison between AUC15 arachidonic-acid (AA) channel and VerifyNow aspirin response units (VN ARU) and between AUC15 adenosine diphosphate (ADP) channel and VerifyNow P2Y12 reactivity units (VN PRU) was obtained from retrospective analysis of data at 370 and 296 time-points respectively.
  
  
  RESULTS
  There was minimal intra-and inter-individual variability in MA and AUC15 in the AA, ADP and thrombin channels. There was a good correlation between AA AUC15 and VN ARU (r = 0.701, p < 0.001) and between ADP AUC15 and VN PRU (r = 0.609, p < 0.001).
  
  
  CONCLUSIONS
  s-TEG is a reproducible and reliable near-patient test that correlates well with VerifyNow. Large scale studies are needed to determine its potential role in individually tailored antiplatelet therapy.
authors.affiliation: Wessex Cardiothoracic Unit, Southampton University Hospital, UK.
authors.forename: Nalyaka
authors.initials: N
authors.lastname: Sambu
authors.forename: Alex
authors.initials: A
authors.lastname: Hobson
authors.forename: Nick
authors.initials: N
authors.lastname: Curzen
mesh_terms: D001241:Aspirin / Q000627:therapeutic use; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology*; D000077144:Clopidogrel; D006801:Humans; D007206:Individuality; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D015203:Reproducibility of Results; D013916:Thrombelastography / Q000379:methods*; D013988:Ticlopidine / Q000031:analogs & derivatives / Q000627:therapeutic use
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin