1124. Influence of Demographic Variation and Vascular Risk Factors on Circle of Willis Completion as Assessed by Digital Subtraction Angiography

Authors: Ryan Eaton; Varun Shah, BS; David Dornbos III, MD; Orel Zaninovich, MD; Travis Dumont, MD; Ciaran Powers (Columbus, OH)

INTRODUCTION: Incomplete Circle of Willis (CoW) configuration is a risk factor for cerebrovascular diseases, including aneurysm formation and ischemic stroke. Previous work using computed tomographic angiography has shown CoW completeness varies with age. This study was performed to characterize CoW variation using digital subtraction angiography (DSA), the gold standard for evaluation of cerebrovascular anatomy, identifying demographic and physiologic features that impact CoW anatomy.

METHODS: A retrospective analysis of 274 patients undergoing cerebral angiography by a single surgeon for any indication was conducted. Three reviewers graded each of the seven major CoW branches as normal, hypoplastic, or aplastic. Hypoplastic was defined as less than 30% the diameter of the distal ipsilateral segment. CoW configuration with any aplastic vessel was considered incomplete. Overall variation incidence was recorded. Pearson’s chi-squared significance testing and logistic regression analyses were conducted to assess the impact of age, gender, race, and co-morbidities on CoW configuration.

RESULTS: A complete CoW was identified in 37.23% of the patients. The most common variants were an aplastic left posterior communicating artery (31.75%) and a hypoplastic right posterior communicating artery (29.56%). Patients aged <40, 40-69, and ≥70 years had a complete CoW in 67.92%, 31.75%, and 18.75%, respectively. In univariate analysis, patients <40 years old were more likely to have a complete CoW (OR 4.973, 95% CI 2.610-9.476, p<0.001) as were patients <70 years old (OR 2.849, 95% CI 1.131-7.194, p<0.05).  Overall, increasing age correlates with total aplastic and hypoplastic vessels (β= 0.291, p<0.001). Other demographic factors and co-morbidities did not significantly affect CoW configuration.

CONCLUSIONS: CoW anatomy, as assessed by DSA, shows considerable variation. Complete CoW is closely related to age; however, further investigation is required to elucidate the impact of other demographic and vascular risk factors on CoW anatomy.