Homocysteine and nitric oxide in patients undergoing diagnostic coronary angiography.

We evaluated the plasma homocysteine (tHcy) and nitric oxide metabolites (nitrite plus nitrate; NOx) data of consecutive patients undergoing diagnostic coronary angiography (n=79) with respect to the presence and severity of coronary artery disease (CAD), the presence of acute coronary syndromes (ACS), and the risk status of patients. Hyperhomocysteinemia (>15 micromol/L) was detected in 11% of the controls (n=19) and 37% of CAD patients (n=60) (p=0.03). Plasma tHcy in CAD patients was not significantly different from controls, but those with 3-vessel disease had a significantly higher tHcy concentrations than did controls (p=0.049). The patients with 3-vessel disease and ACS had the highest concentrations of tHcy (16.9 +- 4.4 micromol/L), and the difference from the ACS patients with 1- and 2-vessel involvement was significant (p=0.03). In patients with 1-vessel involvement, tHcy was correlated with NOx (r=0.62, p=0.005); in patients with 2- and 3-vessel disease this correlation could not be observed. The high-risk patients (n=51) had a higher mean number of vessel involvement and tHcy (p<0.001, p<0.05, respectively) but lower NOx (p<0.05) when compared to the low-risk patients (n=28). It appears that in the early stages of atherosclerosis hyperhomocysteinemia causes an increase in NOx production, but with progression of the disease this compensatory increase disappears.