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Admission international normalized ratio and acute infarct volume in ischemic stroke

Authors

  • Hakan Ay MD,

    Corresponding author
    1. Stroke Service, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
    2. A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
    • Martinos Center for Biomedical Imaging and Stroke Service, Departments of Neurology and Radiology, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Room 2301, Charlestown, MA 02129
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  • Ethem Murat Arsava MD,

    1. A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
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  • Levent Gungor MD,

    1. A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
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  • David Greer MD,

    1. Stroke Service, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
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  • Aneesh B. Singhal MD,

    1. Stroke Service, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
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  • Karen L. Furie MD,

    1. Stroke Service, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
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  • Walter J. Koroshetz MD,

    1. National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
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  • A. Gregory Sorensen MD

    1. A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
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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 (≥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).

Interpretation

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. Ann Neurol 2008

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