The relationship between saphenous coronary bypass graft occlusion and serum gamma-glutamyltransferase activity

OBJECTIVES
Serum gamma-glutamyltransferase (GGT) activity has been shown to be associated with progression of atherosclerosis. We evaluated the relationship between serum GGT levels and saphenous vein bypass graft disease at least one year after coronary artery bypass graft (CABG) surgery.

STUDY DESIGN
The study included 125 consecutive patients who had undergone CABG surgery with at least one saphenous vein graft (SVG) and were referred to cardiac catheterization for stable anginal symptoms or positive stress test results at least one year after CABG surgery. Laboratory parameters including serum GGT levels were measured before angiography. Occluded grafts were defined as a luminal stenosis of ≥70% or absence of distal TIMI 3 flow. Thus, SVGs were found to be patent in 53 patients (42.4%; 40 males, 13 females; mean age 65±8 years) and occluded in 72 patients (57.6%; 62 males, 10 females; mean age 64±9 years).

RESULTS
The two groups were similar with regard to age, gender, hypertension, diabetes mellitus, family history of coronary artery disease, smoking, and alcohol consumption. The mean time from CABG to angiography was similar in patients with a patent and occluded SVG (6.8±4.3 vs. 8.1±3.7 years; p>0.05). Waist circumference was greater (p=0.02) and serum levels of total cholesterol (p=0.001), triglyceride (p=0.02), uric acid (p<0.001), hs-CRP (p<0.001), GGT (p<0.001) and fibrinogen (p<0.001) were significantly higher in patients with occluded veins. Serum GGT level was moderately but significantly correlated with waist circumference (r=0.2, p=0.04), uric acid (r=0.3, p=0.008), and hs-CRP (r=0.3, p=0.002). In logistic regression analysis, total cholesterol (OR=1.012, 95% CI 1.002-1.023, p=0.03), hs-CRP (OR=1.968, 95% CI 1.17-3.311, 0.01), uric acid (OR=1.57, 95% CI 1.1-2.208, p=0.01), and GGT (OR=1.047, 95% CI 1.002-1.1, p=0.04) were found to be significant predictors of SVG occlusion.

CONCLUSION
Our results suggest that serum GGT activity is associated with higher occlusion rates of venous bypass grafts.