DOI: 10.1161/circ.148.suppl_1.13954 ISSN: 0009-7322

Abstract 13954: The Canadian Tia Score as a Predictor of Ischemic Lesion on Magnetic Resonance Imaging in Transient Ischemic Attack or Minor Stroke Following a Negative Computed Tomography Scan

Matthieu Robitaille, Mukul Sharma, Marcel Emond, Ariane Mackey, Pierre-Gilles Blanchard, Marie-Joe Nemnom, Marco Sivilotti, Ian STIELL, Grant Stotts, Jacques Lee, Andrew Worster, Judy Morris, Ka Wai Cheung, Albert Jin, Wieslaw J Oczkowski, Demetrios Sahlas, Heather Murray, Steve Verreault, Marie-Christine Camden, Samuel Yip, Philip A Teal, David J GLADSTONE, Mark Boulos, Nicholas Chagnon, Elizabeth Shouldice, Clare Atzema, Tarik Slaoui, Jeanne S Teitelbaum, George A Wells, Jeffrey J Perry
  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine

Introduction: Patients with a diagnosis of transient ischemic attack (TIA) or minor stroke with an acute infarction on brain imaging are at higher risk of subsequent stroke. Our goal was to establish if the Canadian TIA Score (CTS) could predict infarction on magnetic resonance imaging (MRI) when a computed tomography (CT) scan was negative for stroke and aimed to identify clinical factors predictive of a positive MRI.

Methods: Patients were selected from the prospective cohort used for the validation of the CTS in 13 centers. Patients with negative CT scans who underwent MRI within 7 days were analyzed. The main outcome was cerebral infarction defined as MRI diffusion-weighted imaging (DWI) positivity. Associations between confirmed stroke and demographic characteristics, clinical features, laboratory findings, and medications were determined using a multivariate logistic regression model. Subsequent stroke rate at 7, 30, and 90 days was analyzed.

Results: From 11,507 patients, 1,048 met inclusion criteria. MRI positivity was 15.4%, 30.4%, and 50.0% for the low, medium, and high-risk CTS groups, respectively. Subsequent stroke/TIA rates were higher with confirmed ischemic lesions on MRI at 90 days: twice (10.0%) in the low-risk group, 51 (22.3%) in the medium-risk group, and 20 (24.7%) in high-risk patients. 1.7% of DWI negative patients had a subsequent stroke. Predictive factors in multivariable models for DWI positivity in the medium-risk group were male (OR=1.53; 95% CI 1.11-2.12), hypertension (OR=1.63; 95% CI 1.17-2.27), clinical history of unilateral weakness (OR=2.09; 95% CI 1.50-2.91), language disturbance (OR=1.43; 95% CI 1.03-1.97), and the presence of pronator drift on examination (OR=2.18; 95% CI 1.37-3.47).

Conclusion: The CTS helps predict MRI findings and confirmed ischemic lesion is a predictor of the recurrence risk of stroke. The low-risk group showed few positive MRIs and had a lower recurrence rate justifying less urgent MRI. In the medium-risk group, we highlighted findings that should raise the suspicion of an ischemic lesion and these patients should be prioritize for rapid investigation of stroke etiology. In the high-risk group, patients are at risk for stroke despite negative imaging and MRI should not delay management.

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