Phenotypes of Chronic Covert Brain Infarction in Patients With First-Ever Ischemic Stroke: A Cohort Study.

BACKGROUND AND PURPOSE: The aim of this study was to assess the rate of chronic covert brain infarctions (CBIs) in patients with acute ischemic stroke (AIS) and to describe their phenotypes and diagnostic value. METHODS: This is a single-center cohort study including 1546 consecutive patients with first-ever AIS on magnetic resonance imaging imaging from January 2015 to December 2017. The main study outcomes were CBI phenotypes, their relative frequencies, location, and association with vascular risk factors. RESULTS: Any CBI was present in 574/1546 (37% [95% CI, 35%-40%]) of patients with a total of 950 CBI lesions. The most frequent locations of CBI were cerebellar in 295/950 (31%), subcortical supratentorial in 292/950 (31%), and cortical in 213/950 (24%). CBI phenotypes included lacunes (49%), combined gray and white matter lesions (30%), gray matter lesions (13%), and large subcortical infarcts (7%). Vascular risk profile and white matter hyperintensities severity (19% if no white matter hyperintensity, 63% in severe white matter hyperintensity, P<0.001) were associated with presence of any CBI. Atrial fibrillation was associated with cortical lesions (adjusted odds ratio, 2.032 [95% CI, 1.041-3.967]). Median National Institutes of Health Stroke Scale scores on admission were higher in patients with an embolic CBI phenotype (median National Institutes of Health Stroke Scale, 5 [2-10], P=0.025). CONCLUSIONS: CBIs were present in more than a third of patients with first AIS. Their location and phenotypes as determined by MRI were different from previous studies using computed tomography imaging. Among patients suffering from AIS, those with additional CBI represent a vascular high-risk subgroup and the association of different phenotypes of CBIs with differing risk factor profiles potentially points toward discriminative AIS etiologies.