Admission international normalized ratio and acute infarct volume in ischemic stroke.
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.
Ay
Hakan
H
Department of Neurology, Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA.
Arsava
Ethem Murat
EM
Gungor
Levent
L
Greer
David
D
Singhal
Aneesh B
AB
Furie
Karen L
KL
Koroshetz
Walter J
WJ
Sorensen
A Gregory
AG
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*
D000925:Anticoagulants; D014859:Warfarin