The long-term survival of coronary artery bypass grafting (CABG) surgery depends on the patency of the grafts. A key problem is the lower patency of the saphenous vein (SV) compared to the arterial grafts such as internal thoracic artery (ITA) with unclear reasons despite of previous efforts to reveal them. We hypothesized that the intrinsic differences between the ITA and SV may involve the differences in post-translational modification (PTM) of proteins in these two types of vascular grafts. Hence, we applied PTM proteomics to uncover differences between ITA and SV, and to reveal a novel mechanism for the differences in long-term patency.