title: Prognostic significance of thrombocytopenia during hirudin and heparin therapy in acute coronary syndrome without ST elevation: Organization to Assess Strategies for Ischemic Syndromes (OASIS-2)study.
abstract: BACKGROUND
  The development of thrombocytopenia in acute coronary syndromes (ACS) appears to be associated with adverse clinical outcomes. Unfractionated heparin is a recognized cause of thrombocytopenia, but the incidence, predictors, and prognostic significance of thrombocytopenia during hirudin therapy in ACS have not been reported.
  
  
  RESULTS
  Patients with ACS without ST elevation were randomized in a double-blind manner to receive a 72-hour intravenous infusion of unfractionated heparin or hirudin. Platelet counts were measured at baseline and within 24 hours of completion of study drug. The overall incidence of thrombocytopenia (<100x10(9)/L) was 1% and was similar in unfractionated heparin- and hirudin-treated patients (P:=0.42). Thrombocytopenia during study drug infusion was an independent predictor of 7-day outcomes, including death (OR, 6.7; 95% CI, 1.9 to 25); the composite of death, myocardial infarction, and recurrent ischemia (OR, 2.0; 95% CI, 1.0 to 1.5); revascularization (OR, 4.0; 95% CI, 2.2 to 7.1); and major bleeding (OR, 8.3; 95% CI, 3.4 to 17.7). Among patients who developed thrombocytopenia, hirudin (OR, 5.4; 95% CI, 2.6 to 11.3) but not unfractionated heparin (OR, 2.0; 95% CI, 0.3 to 14.4) therapy was associated with a significantly increased risk of major bleeding.
  
  
  CONCLUSIONS
  Early-onset thrombocytopenia in patients with ACS without ST elevation is strongly associated with adverse clinical outcomes, including death, ischemic events, and bleeding. The excess of major bleeding in hirudin-treated patients who develop thrombocytopenia suggests that thrombocytopenia may contribute to the increased risk of bleeding observed with hirudin.
authors.affiliation: Preventive Cardiology and Therapeutics Program, McMaster University, Hamilton, Canada.
authors.forename: J W
authors.initials: JW
authors.lastname: Eikelboom
authors.forename: S S
authors.initials: SS
authors.lastname: Anand
authors.forename: S R
authors.initials: SR
authors.lastname: Mehta
authors.forename: J I
authors.initials: JI
authors.lastname: Weitz
authors.forename: C
authors.initials: C
authors.lastname: Yi
authors.forename: S
authors.initials: S
authors.lastname: Yusuf
mesh_terms: D000208:Acute Disease; D000789:Angina, Unstable / Q000175:diagnosis* / Q000188:drug therapy / Q000401:mortality; D004311:Double-Blind Method; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use*; D006470:Hemorrhage / Q000209:etiology; D006493:Heparin / Q000627:therapeutic use*; D024764:Hirudin Therapy; D006801:Humans; D016015:Logistic Models; D008297:Male; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000188:drug therapy / Q000401:mortality; D017063:Outcome Assessment, Health Care; D011379:Prognosis; D013921:Thrombocytopenia / Q000453:epidemiology / Q000209:etiology*
chemical_list: D005343:Fibrinolytic Agents; D006493:Heparin