title: Effects of pretreatment with clopidogrel on platelet and coagulation activation in patients undergoing elective coronary stenting.
abstract: BACKGROUND
  Current data suggest that pretreatment with clopidogrel (in addition to aspirin) prior to elective percutaneous coronary intervention (PCI) might be associated with a reduced incidence of subsequent adverse ischemic events. The aim of this placebo-controlled study was to find out whether an extended pretreatment period with clopidogrel before an elective PCI might confer a superior inhibition of the platelet activation and aggregation than clopidogrel given not until PCI.
  
  
  METHODS
  Twenty patients with stable angina being already on aspirin were randomly assigned to receive the loading dose of 300 mg clopidogrel, either 24 h before or immediately after stent implantation. At several time points before and after PCI, the activation of both the platelet and the coagulation system was determined by measuring beta-thromboglobulin (beta-TG) and prothrombin fragment f1.2 (f1.2), respectively, in venous blood and in blood emerging from a microvascular injury (shed blood).
  
  
  RESULTS
  Pretreatment with clopidogrel before PCI exhibited a slight reduction of beta-TG (from 178 to 139 ng/ml, p=0.085) and of f1.2 (from 0.81 to 0.75 nmol/l, p=0.045) in venous blood. Heparin administration (at the beginning of PCI) resulted in a 65% inhibition of ss-TG (from 10,590 to 2833 ng/ml) and 90% inhibition of f1.2 formation (from 38.7 to 4.2 nmol/l) in shed blood of patients with clopidogrel pretreatment. The extent of inhibition was, however, comparable to that observed in patients without clopidogrel pretreatment (beta-TG: from 8025 to 2812 ng/ml, 76% inhibition, p=0.47; f1.2: from 34.9 to 3.8 nmol/l, 86% inhibition, p=0.80). After PTT normalisation (6 h after PCI), levels of beta-TG and f1.2 both in venous blood and in shed blood did not differ between the two treatment regimens up to 48 h after PCI.
  
  
  CONCLUSIONS
  Pretreatment with clopidogrel did not result in a pronounced inhibition of the platelet and coagulation system activation in patients on aspirin undergoing elective coronary stent implantation.
authors.affiliation: Department of Internal Medicine I, Division of Hematology and Hemostasis, Vienna University Hospital, Währinger Gürtel 18-20, A-1090 Vienna, Austria. Ansgar.Weltermann@akh-wien.ac.at
authors.forename: Ansgar
authors.initials: A
authors.lastname: Weltermann
authors.forename: Peter
authors.initials: P
authors.lastname: Fritsch
authors.forename: Paul A
authors.initials: PA
authors.lastname: Kyrle
authors.forename: Verena
authors.initials: V
authors.lastname: Schoenauer
authors.forename: Georg
authors.initials: G
authors.lastname: Heinze
authors.forename: Johann
authors.initials: J
authors.lastname: Wojta
authors.forename: Günter
authors.initials: G
authors.lastname: Christ
authors.forename: Kurt
authors.initials: K
authors.lastname: Huber
mesh_terms: D000787:Angina Pectoris / Q000097:blood / Q000188:drug therapy / Q000601:surgery*; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects*; D001807:Blood Vessel Prosthesis / Q000009:adverse effects*; D000077144:Clopidogrel; D003328:Coronary Thrombosis / Q000097:blood* / Q000188:drug therapy / Q000209:etiology / Q000517:prevention & control*; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D008875:Middle Aged; D015539:Platelet Activation / Q000187:drug effects*; D015607:Stents / Q000009:adverse effects*; D013988:Ticlopidine / Q000008:administration & dosage* / Q000031:analogs & derivatives*; D001620:beta-Thromboglobulin / Q000032:analysis
chemical_list: D001620:beta-Thromboglobulin; D000077144:Clopidogrel; D013988:Ticlopidine