Ultrasonic Plaque Characterization: Results from the Asymptomatic Carotid Stenosis and Risk of Stroke (ACSRS) Study

The Asymptomatic Carotid Stenosis and Risk of Stroke (ACSRS) study was a multicenter natural history study. Its primary aim was to identify clinical, biochemical, and plaque features that, when used in combination, would allow risk stratification for ipsilateral carotid territory hemispheric ischemic events, especially stroke. It was planned in 1996, soon after the publication of the Asymptomatic Carotid Atherosclerosis Study (ACAS),1 and recruitment started in 1998. The ACSRS is the largest natural history study of patients with asymptomatic carotid stenosis performed to date with 1,121 patients followed for 6–96 months (mean 48 months). Results of different aspects such as quality control, stenosis and risk, factors associated with cardiovascular mortality, effect of image normalization on carotid plaque classification, silent ipsilateral cerebral embolic infarcts on computed tomography (CT) brain scans and stroke risk, and stroke risk stratification using baseline plaque texture features have already been published.