Silent MRI infarcts and the risk of future stroke

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Abstract
Background: Silent infarcts are commonly discovered on cranial MRI in the elderly. Objective: To examine the association between risk of stroke and presence of silent infarcts, alone and in combination with other stroke risk factors. Methods: Participants (3,324) in the Cardiovascular Health Study (CHS) without a history of stroke underwent cranial MRI scans between 1992 and 1994. Silent infarcts were defined as focal lesions greater than 3 mm that were hyperintense on T2 images and, if subcortical, hypointense on T1 images. Incident strokes were identified and classified over an average follow-up of 4 years. The authors evaluated the risk of subsequent symptomatic stroke and how it was modified by other potential stroke risk factors among those with silent infarcts. Results: Approximately 28% of CHS participants had evidence of silent infarcts (n = 923). The incidence of stroke was 18.7 per 1,000 person-years in those with silent infarcts (n = 67) compared with 9.5 per 1,000 person-years in the absence of silent infarcts. The adjusted relative risk of incident stroke increased with multiple (more than one) silent infarcts (hazard ratio 1.9 [1.2 to 2.8]). Higher values of diastolic and systolic blood pressure, common and internal carotid wall thickness, and the presence of atrial fibrillation were associated with an increased risk of strokes in those with silent infarcts (n = 53 strokes). Conclusion: The presence of silent cerebral infarcts on MRI is an independent predictor of the risk of symptomatic stroke over a 4-year follow- up in older individuals without a clinical history of stroke.