title: Individualised assessment of response to clopidogrel in patients presenting with acute coronary syndromes: a role for short thrombelastography?
abstract: BACKGROUND
  There is considerable interindividual variation in response to the antiplatelet agent clopidogrel. Hyporesponse predicts negative outcomes in patients presenting with a variety of ischemic cardiac conditions and following intracoronary stent placement. Many tests of clopidogrel activity are time consuming and complex. Short thromboelastography (s-TEG) allows rapid measurement of platelet clopidogrel response.
  
  
  OBJECTIVE
  We initiated this study to investigate the utility of s-TEG in assessing the response to clopidogrel in patients presenting with acute coronary syndromes (ACS) and to compare these results with established clopidogrel monitoring techniques.
  
  
  METHODS
  Patients admitted with unstable angina (UA) or Non ST elevation myocardial infarction (NSTEMI) undergoing coronary angiography were recruited. After routine loading with clopidogrel, all patients were tested with s-TEG and Accumetrics Verify-Now rapid platelet function analyzer (VN-RPFA). We used the modified TEG technique of measuring area under the curve at 15 min (AUC15), which allows a rapid estimation of antiplatelet response. Vasodilator-stimulated phosphoprotein phosphorylation (VASP) was also tested in a subgroup of patients. Clinical follow-up was obtained at 1 year. s-TEG results were correlated with VN-RPFA and VASP findings.
  
  
  RESULTS
  A total of 49 patients (33 male, mean age 63) were recruited and tested with s-TEG and VN-RPFA and a total of 39 patients were also assessed with VASP. s-TEG readings correlated well with VN-RPFA (r(2)= 0.54, P < 0.0001) and VASP (r(2)= 0.26, P= 0.001).
  
  
  CONCLUSIONS
  s-TEG provides timely results which compare to current tests of clopidogrel activity. This technique can also be used to measure a variety of other clotting parameters and as such could develop into a valuable near patient test for the interventional cardiologist.
authors.affiliation: Department of Cardiology, Heart and Lung Centre, New Cross Hospital, Wolverhampton, UK. james.cotton@rwh-tr.nhs.uk
authors.forename: J M
authors.initials: JM
authors.lastname: Cotton
authors.forename: A M
authors.initials: AM
authors.lastname: Worrall
authors.forename: A R
authors.initials: AR
authors.lastname: Hobson
authors.forename: A
authors.initials: A
authors.lastname: Smallwood
authors.forename: V
authors.initials: V
authors.lastname: Amoah
authors.forename: S
authors.initials: S
authors.lastname: Dunmore
authors.forename: A M
authors.initials: AM
authors.lastname: Nevill
authors.forename: R P
authors.initials: RP
authors.lastname: Raghuraman
authors.forename: R
authors.initials: R
authors.lastname: Rajendra
authors.forename: J
authors.initials: J
authors.lastname: Vickers
authors.forename: N
authors.initials: N
authors.lastname: Curzen
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood / Q000188:drug therapy / Q000601:surgery / Q000628:therapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects / Q000295:instrumentation; D015415:Biomarkers / Q000097:blood; D015815:Cell Adhesion Molecules / Q000097:blood; D000077144:Clopidogrel; D001026:Coronary Artery Bypass / Q000009:adverse effects; D016903:Drug Monitoring / Q000379:methods*; D004739:England; D005260:Female; D006801:Humans; D008297:Male; D008840:Microfilament Proteins / Q000097:blood; D008875:Middle Aged; D010750:Phosphoproteins / Q000097:blood; D010766:Phosphorylation; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015607:Stents; D013916:Thrombelastography; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D013997:Time Factors; D016896:Treatment Outcome; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D015415:Biomarkers; D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; D010750:Phosphoproteins; D010975:Platelet Aggregation Inhibitors; D000098662:Vasodilator-Stimulated Phosphoprotein; D000077144:Clopidogrel; D013988:Ticlopidine