Outcomes of Left Subclavian Artery Revascularization Strategies During Zone 2 Thoracic Endovascular Aortic Repair

Intentional coverage of left subclavian artery (LSA) is often necessary during thoracic endovascular aortic repair (TEVAR) to secure an adequate proximal landing zone. However, this may impair blood flow to vital vascular territories with increased risk of stroke, spinal cord ischemia and upper limb ischemia. Current recommendations from the Society for Vascular Surgery (SVS) and European Society for Vascular Surgery (ESVS) support the consideration of LSA revascularization in patients undergoing elective TEVAR with anticipated LSA coverage. In contrast, management in the acute setting is more complex and requires an individualized approach based on clinical urgency and anatomical factors. Revascularization is generally recommended in high-risk clinical scenarios, including patients with dominant left vertebral circulation, compromised or occluded contralateral vertebral artery, an incomplete circle of Willis, or variant vertebral anatomy such as a hypoplastic left vertebral artery terminating in the posterior inferior cerebellar artery or an isolated vertebral artery. Additional indications include prior LIMA grafting, the presence of upper limb dialysis access, anticipated extensive aortic coverage, or an aberrant right subclavian artery in which both subclavian origins may be compromised. Revascularization techniques encompass both open surgical and endovascular approaches. Surgical options include carotid-subclavian bypass, carotid-axillary bypass, and subclavian transposition, while endovascular methods involve branched or fenestrated endografts, chimney and periscope grafts, as well as in situ fenestration. Although surgical techniques provide durable long-term patency, they are associated with a risk of local complications. Endovascular approaches are minimally invasive; however, they may be associated with an increased risk of endoleaks. Anatomical factors also play a central role in determining both the feasibility and outcomes. Preoperative assessment using computed tomography angiography is essential to evaluate aortic arch morphology, proximal landing zone characteristics, branch vessel orientation, and access vessel suitability. In addition, the spatial relationship between the left common carotid artery (LCCA) and LSA, including minimum inter-vessel distances, directly influences the feasibility of branched or fenestrated endografts. Also branch vessel anatomy is equally critical, as LSA diameter, vertebral artery origin, and vessel length determine the suitability for branch incorporation or fenestration techniques. Furthermore, access-related anatomical constraints, particularly iliofemoral vessel diameter and calcification, may significantly limit device delivery.