Objectives: Extracorporeal circulation is associated with the systemic inflammatory response syndrome. The objective of this study was to measure plasma and myocardial matrix metalloproteinase 2 and 9 levels in patients undergoing off-pump coronary artery bypass and coronary artery bypass grafting.
Methods: Twenty patients subjected to coronary artery bypass grafting and 20 subjected to off-pump coronary artery bypass surgery were included in this study. In both procedures blood was collected in 7 equivalent time points up to 12 hours after grafting. The myocardial biopsy specimens were collected before and after extracorporeal circulation in the coronary artery bypass grafting group and after harvesting and completion of proximal anastomoses in the off-pump coronary artery bypass group. Matrix metalloproteinase levels were measured by means of zymography. Myeloperoxidase and tissue inhibitor of metalloproteinase 1 and 2 levels were measured with an enzyme-linked immunosorbent assay.
Results: Coronary artery bypass grafting but not off-pump coronary artery bypass led to a 700- to 900-fold increase of plasma matrix metalloproteinase 9 levels. A small but significant increase in matrix metalloproteinase 2 levels was detected in both procedures. Myocardial matrix metalloproteinase 9 levels significantly increased at the end of coronary artery bypass grafting and off-pump coronary artery bypass. Increased matrix metalloproteinase 9 activity at the end of extracorporeal circulation was accompanied by augmentation of the endogenous matrix metalloproteinase inhibitors tissue inhibitor of metalloproteinase 1 and 2 in plasma, but its magnitude was unable to balance the plasma matrix metalloproteinase 9 increase. The matrix metalloproteinase 9 content in plasma at the end of extracorporeal circulation correlated with the myeloperoxidase plasma concentration (r(2) = 0.8212, P < 0.05).
Conclusion: We propose that release of matrix metalloproteinase 9 might contribute to the extracorporeal circulation-induced inflammatory reactions.