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(Stroke. 2009;40:3252.)
© 2009 American Heart Association, Inc.

Original Contributions

Early Diffusion Weighted MRI as a Negative Predictor for Disabling Stroke After ABCD² Score Risk Categorization in Transient Ischemic Attack Patients

Andrew W. Asimos, MD; Wayne D. Rosamond, PhD; Anna M. Johnson, PhD, MS; Marlow F. Price, RN; Kathryn M. Rose, PhD; Carol V. Murphy, RN, MPH; Charles H. Tegeler, MD Ana Felix, MBBCh

From the Department of Emergency Medicine (A.W.A.) and the Neurosciences and Spine Institute (M.F.P.), Carolinas Medical Center, Charlotte, NC; the Department of Epidemiology (W.D.R., A.M.J., K.M.R., C.V.M.), University of North Carolina School of Public Health, Chapel Hill, NC; the Department of Neurology (C.H.T.), Wake Forest University School of Medicine, Winston-Salem, NC; and the Department of Neurology (A.F.), University of North Carolina School of Medicine, Chapel Hill, NC.

Correspondence to Andrew W. Asimos, MD, PO Box 32861, Charlotte, NC 28232-2861. E-mail andrew.asimos{at}carolinashealthcare.org

Background and Purpose— The prognostic value early diffusion-weighted magnetic resonance imaging (DWMRI) adds in the setting of transient ischemic attack (TIA), after risk stratification by a clinical score, is unclear. The purpose of this study is to evaluate, after ABCD² score risk categorization in admitted TIA patients, whether negative DWMRI performed within 24 hours of symptom onset improves on the identification of patients at low risk for experiencing a disabling stroke within 90 days.

Methods— At 15 North Carolina hospitals, we enrolled a prospective nonconsecutive sample of admitted TIA patients. We excluded patients not undergoing a DWMRI within 24 hours of admission and patients for whom a dichotomized ( or >3) ABCD² score could not be calculated. We conducted a medical record review to determine disabling ischemic stroke outcomes within 90 days.

Results— Over 35 months, 944 TIA patients met inclusion criteria, of whom 4% (n=41) had a disabling ischemic stroke within 90 days. In analyses stratified by low versus moderate/high ABCD² score, the combination of a low risk ABCD² score and a negative early DWMRI had excellent sensitivity (100%, 95% CI 34 to 100) for identifying low-risk patients. In patients classified as moderate to high risk, a negative early DWMRI predicted a low risk of disabling ischemic stroke within 90 days (sensitivity 92%, 95% CI 80 to 97; NLR 0.11, 95% CI 0.04 to 0.32).

Conclusions— After risk stratification by the ABCD² score, early DWMRI enhances the prediction of a low risk for disabling ischemic stroke within 90 days. Further study is warranted in a large, consecutive TIA population of early DWMRI as a sensitive negative predictor for disabling stroke within 90 days.

Key Words: transient ischemic attack • diffusion magnetic resonance imaging • cerebral infarctions