Background and purpose: Transient ischemic attack and minor stroke portend a substantial risk of recurrent stroke. MRI can identify patients at high risk for a recurrent stroke. However, MRI is not commonly available as an emergency. If similarly clinically predictive, a CT/CT angiographic (CTA) imaging strategy would be more widely applicable.
Methods: Five hundred ten patients with consecutive transient ischemic attack and minor stroke underwent CT/CTA and subsequent MRI. We assessed the risk of recurrent stroke within 90 days using standard clinical variables and predefined abnormalities on the CT/CTA (acute ischemia on CT and/or intracranial or extracranial occlusion or stenosis ≥50%) and MRI (diffusion-weighted imaging-positive).
Results: There were 36 recurrent strokes (7.1%; 95% CI, 5.0-9.6). Median time to the event was 1 day (interquartile range, 7.5). Median time from onset to CTA was 5.5 hours (interquartile range, 6.4 hours) and to MRI was 17.5 hours (interquartile range, 12 hours). Symptoms ongoing at first assessment (hazard ratio, 2.2; 95% CI, 1.02-4.9), CT/CTA abnormalities (hazard ratio, 4.0; 95% CI, 2.0-8.5), and diffusion-weighted imaging positivity (hazard ratio, 2.2; 95% CI, 1.05-4.7) predicted recurrent stroke. In the multivariable analysis, only CT/CTA abnormalities predicted recurrent stroke. In a secondary analysis, CT/CTA and MRI were not significantly different in their discriminative value in predicting recurrent stroke (0.67; (95% CI, 0.59-0.76 versus 0.59; 95% CI, 0.52-0.67; P=0.09).
Conclusions: Early assessment of the intracranial and extracranial vasculature using CT/CTA predicts recurrent stroke and clinical outcome in patients with transient ischemic attack and minor stroke. In many institutions, CTA is more readily available than MRI and physicians should access whichever technique is more quickly available at their institution.