Silent brain infarction (SBI) or incidental infarct is common. Recent studies revealed individuals with SBI have an increased risk of future stroke. Even though the 2014 AHA/ASA recommendation for ischemic stroke and transient ischemic attack considered SBI as an entry point for secondary prevention, convincing evidence with regard to the preventive efficacy of antiplatelet therapy against incident stroke in SBI is scant. Investigators examine if antiplatelet therapy can effectively decrease the incidence of future stroke in SBI individuals.

SBI is defined as a focal hyperintense lesion on T2-weighted images and/or fluid-attenuated inversion recovery with no corresponding symptoms in the clinical history of the patient that could be attributed to the lesion. SBI were distinguished from nonspecific subcortical and periventricular white matter lesions by the presence of a corresponding hypointense lesion on T1-weighted images.

The prevalence of SBI varies from 5% to 62% in healthy population. To date, few studies investigate the association between SBI and ethnicity. The effectiveness of antithrombotics including aspirin against future symptomatic stroke in SBI patients remains to be established. Due to the high prevalence of ICAS among Chinese, and its nature of artery-to-artery microembolisms, investigators hypothesize that the prevalence of SBI among Chinese might be significantly higher than other races such as Caucasians and African-Americans.

Recent study has revealed that SBI is associated with an 2-fold increase of future ischemic stroke. Yet, interventions such as antiplatelet therapies for reducing the stroke risk in SBI patients have not been investigated to our best knowledge. In this study, investigators examine whether regular oral aspirin can reduce the incidence of cerebrovascular events and mortality in SBI patients.

Inclusion Criteria:

• cerebral infarction(s) identified by CT/MRI (≥ 3mm in diameter)
• absence of signs or symptoms of neurological dysfunction ascribed to the lesion(s)
• absence of PMH of neurological dysfunctions due to CNS lesion(s)

Exclusion Criteria:

• Age under 45 years or above 80 years
• PMH of ICH within 180 days
• PMH of lobar hemorrhage of anytime
• Neuroimaging evidence suggesting cerebral microbleeds
• High risk of bleeding (e.g. recurrent gastrointestinal or genitourinary bleeding, active peptic ulcer disease)
• Anticipated requirement for long-term use (more than 28 days) of anticoagulants (e.g. recurrent deep vein thrombosis)
• Prior long-term use of anticoagulants (more than 28 days) or antiplatelet agents (more than 28 days)
• Prior retinal stroke/TIA (diagnosed either clinically or by imaging)
• Intolerance or contraindications to aspirin (including thrombocytopenia, prolonged INR)
• Prior ipsilateral carotid endarterectomy/stent
• Stenosis of culprit artery ≥ 70% (detected by ultrasound, MRA, CTA or DSA)
• Atrial fibrillation, or acute myocardial infarction, or acute congestive heart failure
• Impaired renal function: glomerular filtration rate<60
• Mini Mental Status Examination score<24 (adjusted for age and education)
• Medical contraindication to MRI
• Pregnancy or women of child-bearing potential who are not following an effective method of contraception
• Unable or unwilling to provide informed consent
• Unlikely to be compliant with therapy/unwilling to return for frequent clinic visits
• Patients concurrently participating in another study with an investigational drug or device
• Independence ascribed to limb deformity or prior disability
• Acute myocardial infarction
• Acute congestive heart failure
• Other anticipated reasons for future application of antiplatelet agents other than aspirin (eg. recent stenting, interventional surgeries, Lower-Extremity Atherosclerotic Arterial Disease etc)