Association between fetal type posterior cerebral artery and internal carotid artery stenosis

The internal carotid artery (ICA) serves as the main supply artery in individuals with bilateral complete fetal type posterior cerebral artery (BcFTP), a significant anatomical variation that can impact cerebral blood flow distribution. We aimed to determine whether BcFTP was associated with the occurrence of ICA stenosis.

In this observational study, we retrospectively reviewed patients from our comprehensive stroke center whose data were extracted from a prospectively collected digital subtraction angiography (DSA) registry from January 2011 to December 2022. They were classified into the BcFTP group and non-FTP group. The presence of BcFTP and the site and degree of ICA stenosis (evaluated at > 30 % , ≥50 %, and ≥ 70 % thresholds) were determined by two independent neuro-interventionalists blinded to clinical data. To investigate the association between BcFTP and the occurrence of ICA stenosis, a 1:2 ratio propensity score matching (PSM) and conditional logistic regression analysis were conducted.

A total of 9,400 consecutive patients were included in the present study. BcFTP was found in 228 of 9,400 patients (2.4 %). After 1:2 PSM, 228 patients with BcFTP were successfully matched with 456 non-FTP controls. The presence of BcFTP was strongly associated with a significantly lower prevalence of moderate-to-severe (≥50 %) stenosis in both the left ICA (odd ratio [OR] 0.29, 95 % confidence interval [CI] 0.16-0.50, p < 0.001) and right ICA (OR 0.20, 95 % CI 0.11-0.36, p < 0.001). This robust inverse association was consistent across both extracranial and intracranial segments and remained highly significant at the severe (≥70 %) stenosis threshold. In the subgroup analysis stratified by high-risk factors (age, BMI, hypertension, diabetes, hyperlipidemia, and smoking), the association remained significant.

Our research indicates that BcFTP is independently associated with a lower occurrence of ICA stenosis. While causality cannot be determined, these angiographic findings are hypothesis-generating and suggest that anatomical parameters, along with their hemodynamic consequences, may be an important factor associated with the prevalence of ICA stenosis.