ACTIVATION OF THE COMPLEMENT-SYSTEM DURING AND AFTER CARDIOPULMONARY BYPASS-SURGERY - POSTSURGERY ACTIVATION INVOLVES C-REACTIVE PROTEIN AND IS ASSOCIATED WITH POSTOPERATIVE ARRHYTHMIA

Background Complement activation during cardiopulmonary bypass (CPB) s urgery is considered to result from interaction of blood with the extr acorporeal circuit. We investigated whether additional mechanisms may contribute to complement activation during and after CPB and, in parti cular, focused on a possible role of the acute-phase protein C-reactiv e protein (CRP). Methods and Results In 19 patients enrolled for myoca rdial revascularization, perioperative and postoperative levels of com plement activation products, interleukin-6 (IL-6), CRP, and complement -CRP complexes, reflecting CRP-mediated complement activation in vivo, were measured and related to clinical symptoms. A biphasic activation of complement was observed. The ratio between the areas under the cur ve of perioperative and postoperative C3b/c and C4b/c were 3:2 and 1:4 6, respectively. IL-6 levels reached a maximum at 6 hours post-surgery . CRP levels peaked an the second postoperative day. Each complement-C RP complex had peak levels on the second or third postoperative day. B y multivariate analysis, maximum levels of CRP on the second postopera tive day were mainly explained by C4b/c levels after protamine adminis tration, leukocyte count on the second postoperative day, and preopera tive levels of CRP, Peak levels of C4b/c after protamine administratio n (P = .0073) and on the second postoperative day correlated with the occurrence of arrhythmia on the same day (P = .0065). Conclusions Card iac surgery with CPB causes a biphasic complement activation. The firs t phase occurs during CPB and results from the interaction of blood wi th the extracorporeal circuit. The second phase, which occurs during t he first 5 days after surgery, involves CRP, is related to baseline CR P levels, and is associated with clinical symptoms such as arrhythmia.