title: The incidence of heparin-induced thrombocytopenia Type II in patients with subarachnoid hemorrhage treated with heparin versus enoxaparin.
abstract: OBJECTIVE
  Heparin-induced thrombocytopenia Type II (HIT II) is a serious complication that occurs in 0.2-3% of patients treated with heparin and is associated with a high risk of thrombotic events. One center recently reported an incidence of HIT II of 15% in a population of patients with aneurysmal subarachnoid hemorrhage (aSAH). Because these patients are typically exposed to heparin during angiography, controversy exists regarding whether prophylaxis with enoxaparin rather than heparin affords any reduction in the risk of developing HIT II. In this study, the authors investigated the effect of heparin compared with enoxaparin on the incidence of HIT II in patients with aSAH.
  
  
  METHODS
  The authors reviewed the medical records of 300 patients treated for aSAH who received thromboprophylaxis with either heparin or enoxaparin, and identified patients who developed HIT II. The incidences of HIT II in the 2 treatment groups were then compared.
  
  
  RESULTS
  One hundred sixty-six patients with aSAH were treated with heparin, and 134 patients were treated with enoxaparin. Sixteen (5.3%) of 300 patients met the diagnostic criteria for HIT II. Of those treated with heparin, 8 (4.8%) of 166 developed HIT II, compared with 8 (6%) of 134 treated with enoxaparin (difference not significant).
  
  
  CONCLUSIONS
  The authors report a lower incidence of HIT II in patients with aSAH than has previously been reported. The data also suggest that patients with aSAH who receive heparin are at no greater risk of developing HIT II than those who receive enoxaparin. This finding challenges the merit of choosing enoxaparin rather than heparin for thromboprophylaxis in patients with a SAH.
authors.affiliation: Department of Neurological Surgery, Columbia University, College of Physicians and Surgeons, New York, New York, USA. ghkim9@yahoo.com
authors.forename: Grace H
authors.initials: GH
authors.lastname: Kim
authors.forename: David K
authors.initials: DK
authors.lastname: Hahn
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Kellner
authors.forename: Ricardo J
authors.initials: RJ
authors.lastname: Komotar
authors.forename: Robert
authors.initials: R
authors.lastname: Starke
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Garrett
authors.forename: Jiang
authors.initials: J
authors.lastname: Yao
authors.forename: Justin
authors.initials: J
authors.lastname: Cleveland
authors.forename: Stephan A
authors.initials: SA
authors.lastname: Mayer
authors.forename: E Sander
authors.initials: ES
authors.lastname: Connolly
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects* / Q000627:therapeutic use*; D002533:Cerebral Angiography; D015331:Cohort Studies; D017984:Enoxaparin / Q000627:therapeutic use*; D005260:Female; D006493:Heparin / Q000009:adverse effects* / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013345:Subarachnoid Hemorrhage / Q000150:complications / Q000188:drug therapy*; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000453:epidemiology; D013923:Thromboembolism / Q000517:prevention & control; D014057:Tomography, X-Ray Computed
chemical_list: D000925:Anticoagulants; D017984:Enoxaparin; D006493:Heparin