Risk Factors and Implications of the Unplanned Shunt in Carotid Endarterectomy

BACKGROUND: The implications of intraoperative shunting during carotid endarterectomy (CEA) have been studied often with variable recommendations. While some surgeons favor routine shunting to minimize cerebral hypoperfusion, others reserve shunting based on intraoperative monitoring or high-risk clinical features. Predictors of shunt need not remain poorly defined. This study aimed to identify risk factors associated with overall shunt use and unplanned shunting in patients undergoing CEA. METHODS: We performed a retrospective review of a prospectively maintained large academic United States-based health system carotid surgery database between December 2004 and June 2024. Patients were stratified into two groups: procedures performed in absence of a shunt versus unplanned (selective) shunt. Demographic, comorbidity, operative variables, and follow-up results were compared using bivariate analysis. Multivariate logistic regression analysis was performed to identify independent predictors of shunt usage. Missing data were addressed with multiple imputations. RESULTS: A total of 1,453 patients underwent CEA in our database: 617 (42.4%) without shunt and 836 (57.6%) with shunt. Of those who received a shunt, 718 (85.9%) were planned and 118 (14.1%) were unplanned. Multivariate analysis demonstrated predictors of overall unplanned shunt use including prior stroke, beta-blocker use, and thrombolytic therapy before surgery. Patients requiring unplanned shunting had longer clamp times, hospital stays, and ipsilateral stroke rates, though postoperative morbidity and mortality rates were comparable between groups. CONCLUSION: In this cohort, prior stroke, beta-blocker use, and thrombolytic therapy were independently associated with unplanned shunt use during CEA. Among these, thrombolytic exposure prior to CEA conferred the greatest risk. This suggests that combinations of these high-risk factors could potentially guide preoperative decision-making for selective shunting surgeons, minimizing intraoperative stress and cerebral ischemia time.