title: Evaluation of aspirin's effect on platelet function early after coronary artery bypass grafting.
abstract: OBJECTIVE
  Aspirin therapy decreases mortality and ischemic complication rates after coronary artery bypass grafting (CABG). However, platelet inhibition after oral aspirin seems to be insufficient in the early postoperative period. There are incomplete data reporting aspirin efficacy early after CABG. The aim of this study was to assess the pharmacologic effect of aspirin on platelets in the first postoperative days using the most specific laboratory tests for the evaluation of aspirin efficacy.
  
  
  METHODS
  A prospective study.
  
  
  METHODS
  A clinical study in one cardiac surgery center and measurements in two pharmacologic institutions.
  
  
  METHODS
  Thirty patients.
  
  
  METHODS
  Postoperative aspirin efficacy (200 mg/d) was assessed by the suppression of serum thromboxane B(2) (TxB(2)) and by arachidonic acid-induced aggregometry using the MULTIPLATE analyzer. Samples were collected before surgery and on postoperative days 1-5.
  
  
  RESULTS
  The median baseline value (range) of serum TxB(2) was 1.6 ng/mL (1.4-1.9). The median TxB(2) inhibition >90% (the value required for full platelet inhibition) was not achieved until day 5 (-91%, 0.13 ng/mL [0.08-0.22], p < 0.001) and in only 55% of patients. The median baseline ASPI value was 805 (640-975) aggregation units (AU)*min. A significant decrease in aspirin insufficiency was not seen before postoperative day 5 (390 [243-621], p < 0.003) and only 34% of patients reached an effective platelet inhibition on day 5 (cutoff < 300 AU*min).
  
  
  CONCLUSIONS
  The effect of aspirin on inhibition of TxB(2) production and arachidonic acid-induced platelet aggregation is impaired during the first postoperative days after CABG. A more effective antiplatelet strategy presumably could increase early graft patency and improve clinical outcomes after CABG.
authors.affiliation: Cardiocentre, 3rd Department of Internal Medicine and Cardiology, 3rd Medical School, Charles University and Kralovske Vinohrady University Hospital, Prague, Czech Republic. fandabednar@email.cz
authors.forename: Frantisek
authors.initials: F
authors.lastname: Bednar
authors.forename: Tomas
authors.initials: T
authors.lastname: Tencer
authors.forename: Petr
authors.initials: P
authors.lastname: Plasil
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Paluch
authors.forename: Lenka
authors.initials: L
authors.lastname: Sadilkova
authors.forename: Miroslav
authors.initials: M
authors.lastname: Prucha
authors.forename: Milos
authors.initials: M
authors.lastname: Kopa
mesh_terms: D000368:Aged; D001241:Aspirin / Q000494:pharmacology*; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology; D001026:Coronary Artery Bypass; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D011446:Prospective Studies; D013929:Thromboxane B2 / Q000096:biosynthesis
chemical_list: D010975:Platelet Aggregation Inhibitors; D013929:Thromboxane B2; D001241:Aspirin