Background: Previous studies identified a high frequency of silent ischemic lesion recurrence on magnetic resonance imaging (MRI) after an index stroke. Objective: To investigate whether ischemic lesion recurrence on MRI predicts subsequent clinical events. Design: Retrospective cohort study. Setting: General community hospital. Patients: We recruited 120 patients who experienced an acute ischemic stroke (IS) and who underwent initial MRI within 24 hours of onset and subsequent MRI on day 5. Of those patients, 68 underwent follow-up MRI up to 90 days after onset. Main Outcome Measures: Early silent lesion recurrence was defined as new asymptomatic ischemic lesions on 5-day MRI, and late silent lesion recurrence was defined as those on 30- or 90-day MRI. Patients were followed up for recurrent vascular events by interviews. Results: Among the 104 patients (86.7%) who had available clinical outcome data, 35 (33.7%) had early silent lesion recurrence; 15 (22.1%) of 68 patients had late silent lesion recurrence. Of the patients, 8 experienced a recurrent IS, 3 experienced a transient ischemic attack, and 3 had vascular deaths during a mean±SD follow-up of 19.3±9.0 months. For recurrent IS as a clinical end point, late silent lesion recurrence independently predicted recurrent IS (odds ratio, 6.55; 95% confidence interval, 1.09-39.55) by the Cox proportional hazards model. For combined clinical end points, early (odds ratio, 3.19; 95% confidence interval, 1.02-10.00) and late (odds ratio, 8.09; 95% confidence interval, 1.29-50.91) silent lesion recurrences independently predicted clinical recurrent IS, transient ischemic attack, or vascular deaths. Conclusion: These data suggest that silent ischemic lesion recurrence on MRI may be a potential surrogate marker of clinical recurrence.
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