Increased plasma beta-thromboglobulin in patients with coronary artery vein graft occlusion: Response to low dose aspirin

The therapeutic effect of aspirin on vein graft patency was studied in patients undergoing coronary artery bypass graft surgery. The study design enabled the prospective evaluation of the relation of platelet activation, as measured by plasma beta-thromboglobulin concentration, to subsequent coronary vein graft occlusion. Serial beta-thromboglobulin levels were measured in 105 patients randomized to receive aspirin (324 mg/day) or placebo beginning within 1 h after surgery. Graft patency was assessed angiographically at 1 week and 1 year after surgery.Of 49 patients receiving placebo, 17 (34.7%) had one or more graft occlusions, 6 early, 10 late and 1 with both early and late occlusion. Of 56 patients receiving aspirin, 7 (12.5%) had one or more occlusions, 3 early and 4 late (p < 0.01). Preoperatively, the beta-thromboglobulin level in surgical patients (29 ± 13.5 ng/ml) was significantly higher than that of 51 control subjects (22.6 ± 11.1 ng/ml) (p < 0.004).Plasma beta-thromboglobulin levels remained comparatively constant at 3 and 12 months after surgery in the 43 patients who had both samples available (p < 0.001, r = 0.65). The reduction in beta-thromboglobulin concentration from the preoperative level to 12 months postoperatively was greater in the aspirin-treated group (p < 0.001). Multivariate logistic regression analysis demonstrated a significant association between preoperative beta-throboglobulin concentration and graft occlusion (p < 0.02), and aspirin treatment was effective in preventing occlusion when adjusted for the preoperative beta-thromboglobulin level (p < 0.005).Plasma beta-thromboglobulin concentrations are elevated in patients with coronary artery disease, suggesting ongoing platelet activation. The risk of coronary artery bypass graft occlusion is greater in patients with higher preoperative levels of beta-thromboglobulin, a risk that is greatly reduced by aspirin therapy begun within 1 h after surgery and continued for 12 months postoperatively