MRI findings and stroke risk in TIA patients with different symptom durations

Objective: To determine the frequency of acute infarction detected by diffusion-weighted imaging (DWI)-MRI and stroke risk in TIA patients with different symptom duration in a population-based study. Methods: During a 54-month period (starting November 2007), 3,724 admitted patients (mean age, 67 ± 14 years; 45% women) with transient neurologic symptoms lasting <24 hours from 15 hospitals were included. All patients underwent DWI-MRI during hospitalization. Results: Of 3,724 patients, 1,166 showed an acute infarction (32.2%; 95% confidence interval [CI], 30.8%-33.8%) and 88 (2.4%; 95% CI, 1.9%-2.9%) had a stroke during hospitalization (7 days). Stroke risk was higher in patients with tissue-positive DWI than in those with tissue-negative DWI (4.5% vs 1.5%, respectively; p < 0.001). Logistic regression analysis revealed that stroke risk was correlated with positive DWI (odds ratio [OR], 3.1;95% CI, 2.0-4.8; p < 0.001), atrial fibrillation (OR, 2.1;95% CI, 1.3-3.5; p = 0.001), and symptom duration <1 hour (OR, 1.5;95% CI, 1.0-2.4; p = 0.042). Patients with symptoms lasting <1 hour had a lower rate of acute infarction than those with symptoms lasting $1 hour (24% vs 36%, respectively; p < 0.001), whereas stroke risk did not differ between the groups (2.8% vs 2.1%, respectively; p = 0.22). Stroke risk was higher after tissuepositive events than tissue-negative ones in patients with symptom duration <1 hour (5.2% vs 2.0%, respectively; p = 0.002) and in those with symptom duration ≥1 hour (4.1% vs 1.1%, respectively; p < 0.001). Conclusion: Stroke risk was higher after tissue-positive events than tissue-negative ones in TIA patients with different symptom duration.