Early complement activation through alternative pathway significantly correlates to myocardial injury in patients undergoing cardiac surgery (142.6)

Abstract

Global heart ischemia occurs in the normal course of cardiac surgery during aortic cross-clamping (AXCL), and plasma level of cardiac troponin, a specific myocardial injury marker, increases during reperfusion after releasing the clamp. Earlier clinical studies also found C3, the common factor in three complement pathways, is activated during cardiac surgery. In this prospective study, we investigated three complement pathways in the involvement of myocardial injury during cardiac surgery. Fifty patients undergoing open heart surgery were enrolled. Coronary sinus and peripheral blood were collected at different peri-operative time points. Plasma levels of the initial factors in the complement pathways were analyzed. Our results showed that the level of complement factor B, the initial component in the alternative pathway, increased significantly in both coronary sinus and peripheral blood after release of AXCL compared to samples taken prior to AXCL. Spearman correlation analysis showed that this post-AXCL increase in factor B was significantly correlated with the cardiac troponin level sampled immediately after the operation. In contrast, there was no significant correlation between the initial factors in the classical or the lectin complement pathways and post-operation troponin levels. Thus, alternative complement pathway is activated during open heart surgery and may play a role in human myocardial ischemic injury.