Brain Injury and Neuropsychological Outcome After Coronary Artery Surgery Are Affected by Complement Activation

Background: The impact of the postoperative inflammatory response on the central nervous system after cardiac surgery is uncertain. The goal of the study was to evaluate the role of complement activation on cellular brain injury in patients undergoing coronary artery bypass grafting. In addition, neuropsychological functioning was assessed.

Methods: We randomly assigned 30 patients to undergo surgery using either standard noncoated or heparin-coated extracorporeal circuits. Closed cardiopulmonary bypass and controlled suctions of pericardial shed blood were standardized in both groups. Complement activation and cellular brain injury were assessed by measuring sC5b-9 and protein s100beta. Neuropsychometric tests were performed at least 2 weeks before operation and at discharge. They served to calculate z scores of cognitive domains and changes in neuropsychological functioning.

Results: Peak value of sC5b-9 at the end of cardiopulmonary bypass in the noncoated group was significantly higher than in the heparin-coated group (p = 0.005). Changes in the heparin-coated group were not significant. Glial injury started after initiation of surgery and peaked at the end of cardiopulmonary bypass with significantly higher concentration of s100beta in the noncoated than in the heparin-coated group (p = 0.008). Values of s100beta and of sC5b-9 were significantly correlated (p = 0.03). Although no statistically significant between group difference was detected, z scores of attention and flexibility or executive functions were lowered postoperatively within the noncoated group (p = 0.033 and p = 0.028), whereas z scores were unchanged within the heparin-coated group.

Conclusions: Inhibition of complement activation by heparin-coated cardiopulmonary bypass reduced brain cell injury and was associated with preserved neuropsychological functioning after coronary artery bypass grafting.