Late saphenous vein graft occlusion in patients with coronary bypass: possible role of aspirin resistance

Background: Late venous graft thrombosis, leading to recurrent ischemia, is frequently encountered in old, degenerated vein grafts with advanced atherosclerotic plaque formation. Aspirin has been indicated to maintain venous graft patency in the post-operative period. However, there is considerable evidence that aspirin resistance is of concern in patients with venous grafts.Material and Method:Prospectively enrolled 14 patients (11 male, 3 female, Group 1), who were shown to have at least one occluded saphenous vein graft on their late control coronary angiogram after bypass operation, were compared for the presence of aspirin resistance by PFA-100 with age- and sex-matched 14 patients (10 male, 4 female, Group 2), who were found patent and well-functioning vein grafts without wall irregularities on late post-operative coronary angiograms (mean 6.5±2.5 years), enrolled as a control group. Results: Mean CT of collagen/epinephrine cartridge in Group 1 was 197±85 s and significantly less than in Group 2 (279±44 s; p=0.011). It was found that 50% of patients in Group 1 were so-called aspirin resistant, whereas in Group 2, this ratio was 7.1% (p=0.033). BMI (p=0.038, Beta=−0.322), uric acid level (p=0.023, Beta=−0.355), and CT by collagen/epinephrine cartridge (p=0.008, Beta=0.431) were independently predicting late occlusion of saphenous vein graft. Conclusion: Aspirin resistance is highly prevalent in patients with occluded venous grafts at a relatively late period.