Risk index for predicting shunt in carotid endarterectomy.

Background: To prevent ischemia during carotid endarterectomy, a routine or selective shunt can be set up in cases of insufficient cerebral perfusion during the carotid clamping. The aim of this study was to analyze predictive factors for shunting under locoregional anesthesia and to validate a risk index to predict shunt.

Methods: Using a prospective database, we studied carotid endarterectomy performed under locoregional anesthesia between January 1, 2003, and December 31, 2010 (n=1,223). A shunt was used because of clinical intolerance of clamping in 88 cases (group S, 7.2%). Clinical, comorbidities, demographics, and duplex scan data were used to compare group S to a control group (group C, n=1,135, 92.8%). A multivariable logistic regression was performed to identify predictors of shunt. Coefficients were assigned to each predictor to propose a predictive score.

Results: Patients in group S were significantly older than those in group C (75.6±7.8 years vs. 72.6±9.4 years, P<0.001). Other factors associated with a carotid shunt were female sex (odds ratio [OR]=2.41, 95% confidence interval [CI]: 1.54-3.78, P<0.001), systemic arterial hypertension (OR=2.478, 95% CI: 1.16-4.46, P=0.016), occlusion of the contralateral carotid artery (OR=6.03, 95% CI: 2.91-12.48, P<0.001), and 1 factor against the likelihood of a carotid shunt, a history of contralateral carotid surgery (OR=0.34, 95% CI: 0.12-0.93, P=0.037). The mean flow in the contralateral common carotid artery was 696.5±298.0 mL/sec in group S and 814.7±285.5 mL/sec in group C (P<0.001). Using those 6 items, we propose a prognostic score validated in our series and allowing to divided risk of intolerance of clamping into low-risk (≤6%), intermediate-risk (6.1%-15%), and high-risk (>15%) groups.

Conclusions: We have established the first version of a score that predicts the need for a shunt by studying factors associated with intolerance to clamping. The relevance of this score, validated in our series, must be confirmed and adjusted by studies based on a larger sample size.