Oxidative stress and homocysteine in coronary artery disease

Background: Oxidative stress is present in cardiovascular diseases (CVDs), and hyperhomocysteinemia, an independent risk factor for these diseases, may play a role by inducing production of oxygen free radicals. Methods: To evaluate the possible role of homocysteine (Hcy) in inducing oxidative stress in coronary artery disease (CAD), plasma Hey was measured in 68 consecutive cardiovascular patients, and plasma malondialdehyde (MDA), both free and total (free + bound), was measured in 40 patients with CAD (18 with chronic stable angina and 22 with unstable angina). As controls, we tested 70 healthy volunteers. Hey was measured by an immunoenzymatic method and MBA, an index of lipid peroxidation, by gas chromatography-mass spectrometry. Results: Plasma Hey concentrations were significantly higher in cardiovascular patients than in controls (10.2 vs 8.9 mu mol/L; P <0.0002), with no significant difference between values in the stable and unstable angina subgroups. Similarly, total MBA was significantly higher in the CAD group than in the controls (2.6 vs 1.3 mu mol/L; P <0.00001), again with no significant difference between stable and unstable angina patients. By contrast, free MDA, which was significantly higher in the CAD patients than the controls (0.4 vs 0.2 mu mol/L; P <0.00001), was also significantly higher in the unstable than in the stable angina group (0.5 vs 0.3 mu mol/L; P <0.03). However, no correlation was observed among Hey and free and total MDA. Conclusions: Our findings show that a moderate increase of Hcy is associated with CVD but that Hey at the detected values cannot be considered completely responsible for oxidative damage. That lipid peroxidation is involved in CAD is shown by our observation of significantly increased plasma free and total MDA concentrations compared with controls. Moreover, free MDA values discriminated between unstable and chronic stable angina, and could thus represent a new diagnostic tool. (C) 2001 American Association for Clinical Chemistry.