title: Warfarin-associated hemorrhage and cerebral amyloid angiopathy: a genetic and pathologic study.
abstract: BACKGROUND
  Intracerebral hemorrhage (ICH) is the most feared complication of warfarin therapy. The pathogenesis of this often-fatal complication remains obscure. Cerebral amyloid angiopathy (CAA) is a major cause of spontaneous lobar hemorrhage in the elderly and is associated with specific alleles of the APOE gene.
  
  
  OBJECTIVE
  To assess the role of CAA in warfarin-associated ICH.
  
  
  METHODS
  Clinical characteristics and APOE genotype were compared between 41 patients with warfarin-related ICH (from a cohort of 59 consecutive patients aged > or = 65 years with supratentorial ICH on warfarin) and 66 randomly selected individuals aged > or = 65 years without ICH taking warfarin. In addition, all neuropathologic specimens from ICH patients were reviewed for the presence and severity of CAA.
  
  
  RESULTS
  Hemorrhages tended to be in the lobar regions of the brain, and most (76%) occurred with an international normalized ratio of < or = 3.0. The APOE epsilon2 allele was overrepresented among patients with warfarin-associated lobar hemorrhage (allele frequency 0.13 versus 0.04 in control subjects; p = 0.031). After controlling for other variables associated with ICH, carriers of the epsilon2 allele had an OR of 3.8 (95% CI, 1.0 to 14.6) for lobar ICH. CAA was pathologically diagnosed as the cause of lobar hemorrhage in 7 of 11 patients with available tissue samples.
  
  
  CONCLUSIONS
  CAA is an important cause of warfarin-associated lobar ICH in the elderly. Although diagnosis of CAA before hemorrhage is not yet possible, these data offer hope that future patients at high risk for hemorrhage may be identified before initiation of warfarin therapy.
authors.affiliation: Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston 02114, USA.
authors.forename: J
authors.initials: J
authors.lastname: Rosand
authors.forename: E M
authors.initials: EM
authors.lastname: Hylek
authors.forename: H C
authors.initials: HC
authors.lastname: O'Donnell
authors.forename: S M
authors.initials: SM
authors.lastname: Greenberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D001057:Apolipoproteins E / Q000235:genetics; D016657:Cerebral Amyloid Angiopathy / Q000235:genetics* / Q000473:pathology*; D002543:Cerebral Hemorrhage / Q000150:complications / Q000235:genetics* / Q000473:pathology*; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D011446:Prospective Studies; D014859:Warfarin / Q000009:adverse effects*
chemical_list: D001057:Apolipoproteins E; D014859:Warfarin