title: Heparin-induced thrombocytopenia after cardiac surgery: an observational study of 1,722 patients.
abstract: OBJECTIVE
  To assess the characteristics and prognosis of patients in whom heparin-induced thrombocytopenia (HIT) was confirmed (HIT+) among suspected HIT patients after having cardiac surgery and to assess the accuracy of two HIT scoring systems.
  
  
  METHODS
  An observational prospective study.
  
  
  METHODS
  A cardiac surgery unit of a tertiary center from November 2005 to September 2007.
  
  
  METHODS
  Of the 1,722 patients who underwent cardiac surgery, 63 were suspected of HIT based on a platelet count <100 × 10(9)/L, a decrease in platelet count of >30%, or the occurrence of a thrombotic event.
  
  
  METHODS
  The HIT criteria were as follows: (1) the absence of another cause of thrombocytopenia, (2) positive antiplatelet factor 4 (PF4) antibodies (>0.5 optical density [OD]/mn) on enzyme-linked immunoabsorbent assay, and (3) recovery in platelet count after the discontinuation of heparin and substitution by danaparoid sodium.
  
  
  RESULTS
  HIT was confirmed in 24 patients (1.4% [0.8%-1.9%]); 23 belonged to the 984 treated by intravenous unfractionated heparin (IVUH) (2.3% IQ [1.4%-3.3%]) and 1 to the 738 treated by low-molecularweight heparin (0.14% [0.13%-0.4%]) (OD = 17.6; 95% confidence interval, 2.4-131; p < 0.0001). In the HIT+ patients compared with the unconfirmed HIT patients, thrombocytopenia occurred 7 (range, 6-9) days after surgery versus 3 (range, 3-5) days (p < 0.0001), and kinetics of platelet count showed a biphasic pattern. Six HIT+ patients (25% [7.7-42.3]) presented with an arterial thromboembolic event. Diagnosis performances of HIT scoring systems were low.
  
  
  CONCLUSIONS
  Confirmed HIT occurred predominantly in patients treated with IVUH. The timing of thrombocytopenia and the variation pattern of the postoperative platelet count are key factors in diagnosing HIT. The overall incidence of intracardiac thrombotic events was noted to be high.
authors.affiliation: Univ Paris Diderot, Sorbonne Cité, Département d'Anesthésie Réanimation, Paris, France. pascale.piednoir@bch.aphp.fr
authors.forename: Pascale
authors.initials: P
authors.lastname: Piednoir
authors.forename: Nicolas
authors.initials: N
authors.lastname: Allou
authors.forename: Sophie
authors.initials: S
authors.lastname: Provenchère
authors.forename: Clarisse
authors.initials: C
authors.lastname: Berroeta
authors.forename: Marie-Geneviève
authors.initials: MG
authors.lastname: Huisse
authors.forename: Ivan
authors.initials: I
authors.lastname: Philip
authors.forename: Nadine
authors.initials: N
authors.lastname: Ajzenberg
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D005260:Female; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013921:Thrombocytopenia / Q000139:chemically induced*
chemical_list: D000925:Anticoagulants; D006493:Heparin