Background Up to 28% of patients undergoing carotid endarterectomy (CEA) are estimated to experience neurocognitive dysfunction following surgery. The complement cascade plays a central role in ischaemia-reperfusion injury. The authors investigated the effect of common polymorphisms in the complement component 3 (C3F) and complement factor H (CFH Y402H) genes on incidence of neurocognitive dysfunction post-CEA.

Methods This study examined a nested cohort of prospectively recruited patients receiving elective CEA, who were genotyped for the C3F or Y402H polymorphisms. Each patient underwent a standard battery of eight neuropsychometric tests before, and 1 day and 30 days after, surgery.

Results 57 of 142 (40%) CEA patients had at least one copy of the C3F allele (C3F⁺), and 17 of 137 (12%) patients had two copies of the CFH Y402H allele (Y402H⁺⁺). At postoperative day 1, patients were three times (OR 3.05, p=0.045) or six times (OR 6.41, p=0.006) more likely to experience moderate-to-severe neurocognitive dysfunction if they carried the C3F⁺ or Y402H⁺⁺ genotype, respectively. Patients with both risk genotypes had an almost eightfold risk of dysfunction (OR 7.67, p=0.046). Right-hand-dominant C3F⁺ subjects undergoing right-side CEA performed significantly worse on tests of visuospatial function than C3F^– subjects. At day 30, C3F⁺ and Y402H⁺⁺ genotypes trended towards significance as predictors of dysfunction (p=0.07 and p=0.22, respectively).

Conclusion The C3F and Y402H polymorphisms are strong independent predictors of moderate-to-severe neurocognitive dysfunction at 1 day following CEA. Furthermore, patients undergoing right-sided CEA are predisposed to deficits associated with cortex ipsilateral to the operative carotid artery.