Association Between Incomplete Circle of Willis and Carotid Vulnerable Atherosclerotic Plaques.

Objective- Carotid high-risk plaque, characterized by intraplaque hemorrhage, fibrous cap rupture, and large lipid-rich necrotic core, is associated with cerebrovascular events. This study sought to investigate the relationship between high-risk carotid plaque and an incomplete circle of Willis (COW). Approach and Results- Patients were recruited from a multicenter study, Chinese Atherosclerosis Risk Evaluation (CARE-II) and underwent 3-dimensional time-of-flight magnetic resonance angiography for intracranial arteries and 2-dimensional multicontrast magnetic resonance vessel wall imaging for carotid arteries on a 3.0T magnetic resonance scanner. The integrity of the COW in anterior and posterior portions was evaluated. Characteristics of carotid plaques were assessed. Correlation between incomplete COW and carotid plaque features was determined. Of 482 eligible patients, patients with carotid intraplaque hemorrhage showed significantly higher prevalence of an incomplete anterior COW (52.7% versus 38.5%; P=0.022) compared with those without. An incomplete anterior COW was associated with intraplaque hemorrhage before (odds ratio, 1.781; 95% CI, 1.083-2.931; P=0.023) and after adjusted for clinical risk factors (odds ratio, 1.945; 95% CI, 1.139-3.321; P=0.015). The unilateral carotid artery stenosis showed no correlation with incomplete anterior COW and posterior COW (all P>0.025). No significant associations were found between other plaque features and any type of incomplete COW (all P>0.025). Conclusions- An incomplete COW is independently associated with intraplaque hemorrhage of carotid atherosclerotic plaques. Clinical Trial Registration- URL: http://www.clinicaltrials.gov . Unique identifier: NCT02017756.