Impact of Left Subclavian Artery Clamping on Cerebral Oxygenation and Early Outcomes During Hemi‐Arch Replacement With Unilateral Antegrade Cerebral Perfusion

Background The optimal management of the left subclavian artery (LSA) during hemi‐arch replacement with unilateral antegrade cerebral perfusion (ACP) remains controversial. Routine LSA clamping has been proposed to improve cerebral perfusion by preventing potential steal phenomena; however, its clinical benefit remains uncertain. This study aimed to evaluate the association between LSA clamping and intraoperative cerebral oxygenation as well as early clinical outcomes. Methods This was a retrospective single‐center cohort study of 145 patients undergoing hemi‐arch procedures between 2016 and 2022. Patients were divided into LSA clamping ( n = 56) and nonclamping ( n = 89) groups. The primary outcome was the percentage decrease in regional cerebral oxygen saturation (rSO 2 ) measured by near‐infrared spectroscopy during ACP. Secondary outcomes included neurological events, postoperative complications, and early mortality. Results Baseline demographic and operative characteristics appeared comparable between groups. The magnitude of rSO 2 decrease during ACP was similar between LSA clamping and nonclamping groups for both the right (12.0% vs. 10.6%, p = 0.42) and left hemispheres (6.8% vs. 8.8%, p = 0.56). Clinically relevant cerebral desaturation (≥ 20% decrease) occurred at similar rates between groups. Permanent cerebrovascular events were observed in 7.1% and 6.7% of patients, respectively ( p = 0.92). Early mortality occurred in 12.5% of the LSA clamping group and 11.2% of the nonclamping group ( p = 0.81). Mortality was markedly higher in emergent and salvage procedures compared with elective and urgent operations. Conclusion In this single‐center retrospective cohort, routine LSA clamping was not associated with improved cerebral oxygenation or early clinical outcomes during hemi‐arch replacement performed with short‐duration unilateral ACP. These findings suggest that routine LSA clamping may not provide additional benefit in selected patients; however, results should be interpreted cautiously given the observational design and potential era‐related confounding.