title: Admission international normalized ratio and acute infarct volume in ischemic stroke.
abstract: OBJECTIVE
  The level of anticoagulation at the time of stroke onset may influence the size, composition, and dissolution rate of the occlusive clot. We explored the relation between admission international normalized ratio (INR) and acute infarct volume in patients with ischemic stroke.
  
  
  METHODS
  We studied 93 consecutive patients with preadmission warfarin use who had INR measurement and diffusion-weighted imaging performed within 24 hours of stroke onset. Ninety-three etiologic stroke subtype-matched patients without prior warfarin use served as control patients. Linear regression analysis was used to test for independence of INR as a predictor of infarct volume.
  
  
  RESULTS
  In patients with preadmission warfarin use, admission INR was inversely correlated with lesion volume on diffusion-weighted imaging (r = -0.38). This relation was retained after adjustment for potential covariates (p = 0.014). INR less than 2.0 was associated with 3.5-fold (95% confidence interval, 2.9-4.2) greater lesion volume on diffusion-weighted imaging as compared with INR of 2.0 or more. Patients who were on therapeutic INR (>or=2.0) had smaller infarcts compared with patients without preadmission warfarin use (p = 0.001). Admission INR was inversely correlated with acute perfusion defect (r = -0.33), chronic infarct volume (r = -0.42), National Institutes of Health Stroke Scale score at admission (r = -0.27), and modified Rankin score at discharge (r = -0.28).
  
  
  CONCLUSIONS
  These results suggest that preadmission warfarin use associated with therapeutic level of anticoagulation can offer a benefit in limiting the extent of ischemic injury in an event of acute stroke.
authors.affiliation: Department of Neurology, Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA.
authors.forename: Hakan
authors.initials: H
authors.lastname: Ay
authors.forename: Ethem Murat
authors.initials: EM
authors.lastname: Arsava
authors.forename: Levent
authors.initials: L
authors.lastname: Gungor
authors.forename: David
authors.initials: D
authors.lastname: Greer
authors.forename: Aneesh B
authors.initials: AB
authors.lastname: Singhal
authors.forename: Karen L
authors.initials: KL
authors.lastname: Furie
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Koroshetz
authors.forename: A Gregory
authors.initials: AG
authors.lastname: Sorensen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage; D001921:Brain / Q000098:blood supply / Q000187:drug effects / Q000473:pathology; D020520:Brain Infarction / Q000188:drug therapy* / Q000473:pathology* / Q000517:prevention & control; D002545:Brain Ischemia / Q000188:drug therapy* / Q000473:pathology* / Q000517:prevention & control; D002536:Cerebral Arteries / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D002543:Cerebral Hemorrhage / Q000139:chemically induced / Q000503:physiopathology / Q000517:prevention & control; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D019934:International Normalized Ratio / Q000706:statistics & numerical data*; D020766:Intracranial Embolism / Q000188:drug therapy / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data; D012044:Regression Analysis; D012189:Retrospective Studies; D018570:Risk Assessment; D016896:Treatment Outcome; D014859:Warfarin / Q000008:administration & dosage*
chemical_list: D000925:Anticoagulants; D014859:Warfarin