Using serum s100-β protein as a biomarker for comparing silent brain injury in carotid endarterectomy and carotid artery stenting.

Background: S100-β protein has been introduced as a sensitive biomarker of silent cerebral injury. This study compares its serum levels before, during, and 24 hours after carotid artery stenting (CAS) and carotid endarterectomy (CEA).

Methods: We measured serum level of S100-β in arterial blood before (S100Ba), during (S100Bb), and 24 hours after (S100Bc) CAS and CEA. We assessed differences in S100-β levels using non-parametric tests. We analyzed the relationship between carotid plaque type (echolucency) and S100-β protein level. We also examined its relation to the oximetry results in the CEA group (ipsilateral and contralateral).

Results: Thirty patients were enrolled, including 15 CAS and 15 CEA patients, with no significant differences in baseline atherosclerotic characteristics. There was no significant difference in S100Ba or S100Bb levels between CAS and CEA patients. However, a significant difference was found in S100Bc: 331.3 pg/mL (IQ range 56.4-583.5) for CAS vs. 76.3 pg/mL (IQ range 29.7-117.4) for CEA (P=0.01). Type I and II plaques were associated with the higher S100Bc levels in CAS (P=0.048). S100Bc was higher in CEA patients when the contralateral cerebral hemisphere had oximetry values less than 60% (P=0.043).

Conclusions: Our study suggests that CAS might produce silent brain injury. Moreover, vulnerable plaques might be associated with higher levels of S100-β protein, especially in CAS. This pilot study demonstrates that S100-β is a useful biomarker for silent brain injury in carotid revascularization. Large scale studies are still needed to confirm these findings.