Is Vertebral Artery and Posterior Inferior Cerebellar Artery Dominance a Risk Factor for Thromboembolism During Coil Embolization of Unruptured Posterior Circulation Aneurysms?

Background: To retrospectively analyze our clinical data to determine the risk factors for thromboembolism, especially with unruptured posterior circulation coil embolization.

Methods: A total of 53 coil embolization procedures for unruptured posterior circulation aneurysms performed in 53 patients between October 2010 and August 2018 were included. Data about risk factors of thromboembolism in the medical records were collected, such as demographics (sex and age), diabetes mellitus, hypertension, dyslipidemia, smoking, and other underlying diseases. Data on the effect of antiplatelet agents were analyzed with the VerifyNow test. Angiographic data were analyzed to determine aneurysm location and maximum diameter of the aneurysm sac. In addition to these risk factors, relationships between the guiding catheter and anatomic variation of posterior circulation were also evaluated by dividing the cohort into 2 groups.

Results: Thromboembolism was more likely to occur in the same-sided group (81.3% vs. 45.9%; P = 0.033). Accordingly, multivariate analysis revealed 2 risk factors for thromboembolism: same-sided (odds ratio [OR] = 6.12; 95%, confidence interval [CI], 1.369-27.387; P = 0.018) and stent deployment (OR, 3.90; 95% CI, 1.133-3.466; P = 0.031).

Conclusions: In cases of posterior circulation aneurysm coil embolization, if we place the guiding catheter into the side of the dominant posterior inferior cerebellar artery (PICA), then the risk of thromboembolism within the PICA territory could be higher. Accordingly, when faced with this situation, several solutions might be considered, such as changing the antiplatelet strategy or adding an intermediate catheter.