title: Platelet hyper-function in acute coronary syndromes.
abstract: Previous studies have demonstrated shortened bleeding times in patients with acute coronary syndromes, especially in myocardial infarction (MI). In this study we have investigated platelet hyper-function using the PFA-100 with collagen/adenosine diphosphate and collagen/epinephrine cartridges in 78 patients presenting with acute chest pain. Patients were classified into MI, unstable angina (UA) and non-specific chest pain. All patients received 300 mg aspirin (ASA) more than 2 h before blood samples were collected. Twenty healthy normal subjects were also tested before and 2 h after 300 mg ASA (n = 10). The collagen/adenosine diphosphate closure time was significantly shorter in MI patients (median, 71 s; P = 0.0237) but not in UA patients (median, 81 s; P > 0.05) compared with normal subjects (median, 92.5 s). The collagen/epinephrine closure times were significantly longer in UA patients (median, 233 s) than in untreated controls (median, 125 s; P < 0.0001), as expected, but there was no difference in MI patients (median, 149.24 s; P > 0.05), suggesting that the MI patients were not all responding to ASA. Analysis of a subset of the apparent ASA non-responders (n = 5) by platelet aggregation demonstrated that this was not related to failure of ASA to block cyclo-oxygenase activity. Von Willebrand factor levels were significantly elevated in both UA and MI patients compared with normal subjects (mean, 175.5 and 248.9 versus 89.1 s; P < 0.0001 and P < 0.0001, respectively) and were also significantly higher in the MI group compared with the UA group (P < 0.05). There is evidence for platelet hyper-function and elevated von Willebrand factor levels in the MI group that could explain their decreased responsiveness to ASA on the collagen/epinephrine cartridge.
authors.affiliation: Haemostasis Research Unit, Department of Haematology, University College London, UK. Paul.Harriosn@ndm.ox.ac.uk
authors.forename: Paul
authors.initials: P
authors.lastname: Harrison
authors.forename: Ian
authors.initials: I
authors.lastname: Mackie
authors.forename: Anthony
authors.initials: A
authors.lastname: Mathur
authors.forename: Monique S C
authors.initials: MS
authors.lastname: Robinson
authors.forename: Ying
authors.initials: Y
authors.lastname: Hong
authors.forename: Jorge D
authors.initials: JD
authors.lastname: Erusalimsky
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Machin
authors.forename: John F
authors.initials: JF
authors.lastname: Martin
mesh_terms: D000284:Administration, Oral; D000789:Angina, Unstable / Q000097:blood* / Q000188:drug therapy; D001241:Aspirin / Q000008:administration & dosage*; D001760:Bleeding Time; D005260:Female; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000097:blood* / Q000188:drug therapy; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D010979:Platelet Function Tests; D014841:von Willebrand Factor / Q000032:analysis
chemical_list: D010975:Platelet Aggregation Inhibitors; D014841:von Willebrand Factor; D001241:Aspirin