Association between paraoxonase activity and late saphenous vein graft occlusion in patients with coronary artery bypass grafting

Background: Coronary vein graft disease is an important contributor to the morbidity after coronary artery bypass grafting (CABG). Late occlusion of the graft is a serious complication that limits the use of the saphenous vein as a coronary bypass conduit. It is frequently encountered in old, degenerated vein grafts with advanced atherosclerotic plaque formation. Paraoxonase-1 (PON-1) is an HDL-bound enzyme which has anti-atherogenic properties and protects LDL cholesterol from oxidative modification. Aim: To examine the association between PON-1 activity and late saphenous vein graft occlusion. Methods: Thirty-eight patients who had at least one occluded saphenous vein graft (group 1;12 females, 26 males) and 41 patients who had a patent saphenous vein graft (group 2; 7 females, 34 males) were enrolled in this study. Paraoxonase activity was measured spectrophotometrically. Results: The mean PON-1 activity in group 1 was significantly lower than in group 2 (74.1 +/- 52.1 vs. 114.4 +/- 90.9 U/l, p = 0.02). The mean platelet volume was significantly higher in group 1 than group 2 (8.8 +/- 1.6 vs. 8.2 +/- 1.1 fl, p = 0.04). Multiple logistic regression analysis showed that only PON-1 activity (beta = 0.011, p = 0.042) was an independent predictor of late occlusion of a saphenous vein graft. Conclusions: Our results show that PON-1 activity is lower in patients with late saphenous vein graft occlusion. Reduced PON-1 activity may lead to acceleration of saphenous vein graft occlusion.