The association of plasma homocysteine, coronary risk factors and serum nitrite in patients with coronary artery disease, vascular syndrome x and healthy subjects.

Objective: We evaluated the association of plasma total homocysteine (tHcy), cardiac risk factors and total nitrite in coronary artery disease (CAD) patients, cardiac syndrome X patients and in healthy subjects.

Methods: Forty two CAD, 22 cardiac syndrome X patients and 30 healthy subjects, aged 30 to 75 years were included into the study. Blood samples of tHcy, serum total nitrite and cardiac risk factors were studied appropriately. The results were compared between the groups. The independent contributions of tHcy and total nitrite to CAD and cardiac syndrome X and their interactions with cardiac risk factors were evaluated.

Results: After adjusting for age, median values of tHcy and total nitrite were evaluated for their skewness. Coronary artery disease patients had higher median plasma tHcy levels than cardiac syndrome X patients (p<0.001) and healthy subjects (p<0.001) and lower serum total nitrite levels than patients in the two other groups (p<0.05), respectively. Using a univariate linear regression analysis tHcy had a moderately significant positive correlation with age (beta=0.34, p=0.002) and a weakly significant inverse correlation with female gender (beta=-0.24, p=0.032). Using a partial correlation analysis by controlling for age, gender and clinical situations tHcy had a positive but moderately significant correlation with LDL cholesterol (r=0.23, p=0.01) and triglycerides (r=0.27, p=0.016). Total nitrite had a positive but weakly significant correlation with HDL cholesterol (r=0.23, p=0.04) and fibrinogen (r=0.24, p=0.03) and an inverse but moderately significant correlation with LDL cholesterol (r=-0.37,p=0.001). Using a multivariate stepwise regression analysis total nitrite was inversely and significantly associated with tHcy (beta=-0.45) in the control group. The contribution of HDL cholesterol to the association was beta=-0.45, p=0.044, R2=36.2%, HDL cholesterol with fibrinogen--beta=-0.45, p=0.05, R2=36.6% and HDL cholesterol with LDL cholesterol--beta=-0.45, p=0.05, R2=36.3%. In a forward stepwise logistic regression analysis the age adjusted odds ratio (OR) for coronary artery disease per standard deviation change in log-transformed tHcy concentration was - 0.82, p=0.013 and in total nitrite concentration was - 1.08, p=0.02. Using the same model neither tHcy nor total nitrite was associated with cardiac syndrome X (p=0.221 and p=0.112), respectively.

Conclusion: The low nitrite levels can be a marker of endothelial dysfunction in the presence of hyperhomocysteinemia and other cardiac risk factors. Our results might support endothelial dysfunction in CAD but not in cardiac syndrome X patients.