Anatomical and geometric considerations for transradial versus transfemoral approach to extracranial carotid artery stenting

Background and purpose: The transradial (TR) approach is an alternative to the traditional transfemoral (TF) approach for extracranial carotid artery stenting (eCAS). A successful eCAS may be contingent on the geometry of the great vessels. We aimed to analyze the vessel geometry to identify predictors for successful stent placement, enabling tailored approaches. Materials and methods: Multicenter retrospective data was collected from the electronic health record of patients who underwent eCAS from January 2018 to December 2022. Geometric parameters for great vessels were measured using computed tomography angiography (CTA) or magnetic resonance angiography (MRA). A successful approach was defined as completing eCAS without conversion. We performed a geometric analysis of features correlated with complications and successful completion of eCAS. Results: 1346 patients underwent TF (1081) and TR (265) eCAS. Conversion from TR to TF occurred in 44 cases (17%). Three TF cases required conversion. Complication rates did not differ between approaches (P =.773), but converting to TF had significantly higher Category 1 complications (P <.001). A smaller angle of origin of the left common carotid artery (A3) correlated with increased complications (P =.039), particularly with angles <90°, peaking at 50°. No other geometric features predicted the success. Conclusion: Both TR and TF stenting can be safely performed for carotid disease, but the angle of the left carotid artery origin predicted an increased risk of complications. No other aortic arch types or great vessel geometry predicted complications. Conversion from TR to TF predicted increased stroke, ICH, and MI.