Background: Late failure of arterial aortocoronary conduits may result from abnormal activity of cells found in the vessel wall, including macrophages. The purpose of this study was to assess if there are any associations between the number of macrophages and overexpression of matrix metalloproteinases (MMPs) in the wall of arterial grafts, as well as their clinical significance.
Methods: This study involved 128 consecutive patients with a mean age of 64.9 ± 9.7 years who underwent elective surgery for coronary artery disease (CAD). The surplus segments of internal thoracic artery (ITA) and radial arteries (RA) were taken for immunohistochemical analysis of macrophage numbers and MMPs expression. The participants who reached the clinical primary end-point (cardiacrelated death, acute coronary syndrome or progression of CAD) had a follow-up angiography.
Results: The mean numbers of macrophages were higher on RA (70 [24; 112]) than ITA cross-sections (44 [24; 59]; p < 0.001). Median expression of both MMP2 and MMP9 were stronger in the ITA than RA cross-sections (p < 0.001). A significant positive correlation of MMP2 expression and a number of macrophages infiltrating the tunica media of arterial segments were noted on both ITA and RA cross-sections. In addition, the arterial segments of the 6 patients who reached clinical end-point had higher numbers of macrophages and stronger MMP2 expression when compared to the rest of the participants.
Conclusions: Macrophage infiltration of arterial wall grafts prior to harvesting may be associated with higher risk of late occlusion and MMP2 might be facilitating this process.
Keywords: arterial aortocoronary grafts; coronary artery bypass grafting; macrophage; matrix metalloproteinase; outcomes.