Abstract 3094: Diffusion-Positive Cerebral Ischemia with Transient Symptoms - Is it Transient Ischemic Attack or Minor Ischemic Stroke? A Formal Analysis of Demographics, Risk Factors, and Prognosis

Background: The classification of patients with minor cerebral ischemic events is evolving. Under the classical time-based definition of TIA, cerebral infarcts with transient symptoms (CITS) were classified as TIA, while it is classified as minor ischemic stroke (MIS) under the modern tissue-based definition. However, arguments for this reclassification have been largely based on pathologic principles rather than formal analysis of whether CITS patients clinically more resemble DWI-negative TIA patients or MIS patients in demographics, clinical features, and prognosis. Methods: We analyzed consecutive patients recorded in a prospectively maintained database with symptoms of presumed focal ischemic origin either lasting less than 24 hours or with minor neurologic deficits (NIHSS≤5) lasting more than 24 hours. Patients had to present within 48 hours of symptom onset and have undergone acute DWI. Patients were excluded if ischemia occurred immediate after carotid endarterectomy or stenting. Clinical variables, ABCD 2 score, presence of DWI abnormality, relevant large artery disease (≥ 50% stenosis or occlusion of ipsilateral intracranial or extracranial vessels), and stroke recurrence within 90 days were recorded for analysis. Results: Among 416 patients meeting inclusion criteria (mean age 67 years, female 47.1%), 108 (26.0%) were CITS, 149 (35.8%) were DWI-negative TIA, and 159 (38.2%) were MIS. Compared with DWI-negative TIA patients, CITS patients were younger (65 vs. 70 years, p=0.017), had more coronary artery disease (25.9% vs. 14.1%, p=0.024) and relevant large artery disease (45.2% vs. 20.8%, p 0.05), however, both were substantially higher than in DWI-negative TIA patients (2.5%). In multivariate logistic regression analysis performed across the entire cohort, the independent predictors of recurrent stroke were presence of DWI lesion (OR 4.95, 95% CI 1.11-22.09) and relevant large artery disease (OR 3.58, 95% CI 1.47-8.73). Conclusion: DWI-positive cerebral ischemia with transient symptoms more resembles MIS than DWI-negative TIA in risk factor profile and prognosis of patients. DWI abnormality and large artery disease, rather than clinical variables, are the predominant determinants of early stroke recurrence. These results emphasize the utility of urgent MR imaging in patients with minor cerebral ischemic episodes and support the rationale of tissue-based definition of TIA over time-based definition.