Clinical Significance of the Circle of Willis in Patients with Symptomatic Internal Carotid Artery Occlusion

Abstract

Despite improvements in medical treatment, many patients experience ischemic stroke owing to internal carotid artery occlusion. We retrospectively evaluated a novel method based on the arterial structure of the circle of Willis (CoW) to identify patients at a high risk of recurrent stroke. The study enrolled 104 patients with symptomatic occlusion of the internal carotid artery. CoW integrity was evaluated by a quantitative scoring system based on conventional angiography. Patients were categorized into a good integrity (n= 45) or poor integrity (n=59) group. Primary endpoint was early neurologic deterioration, recurrent ischemic stroke, or transient ischemic attack. History of ischemic stroke before initial presentation was more prevalent in the poor integrity group (22.2% vs. 47.5%, P= 0.01), and there were no differences between the 2 groups in terms of stroke risk factors. Overall estimated rate of the primary endpoint was 25.6% 2 years after angiography. It was 5.7% in the good integrity group and 39.8% in the poor integrity group (P < 0.001). In a Cox regression analysis, male sex (P= 0.01, hazard ratio=6.60), use of a tissue plasminogen activator (P= 0.00, hazard ratio= 6.10), and poor integrity of CoW (P= 0.00, hazard ratio= 5.42) were risk factors for the primary endpoint. Patients in the poor integrity group with decreased vascular reserve experienced frequent primary endpoint events compared with patients in the good integrity group (P= 0.00). Patients with poor integrity of CoW are vulnerable to recurrent ischemic stroke and appear to require more aggressive treatment.