Elevated plasma myeloperoxidase levels in relation to circulating inflammatory markers in coronary artery disease

Aims: Elevation of the leukocyte enzyme myeloperoxidase (MPO) in stable coronary artery disease (CAD) is controversial and its relationship with oxidized low-density lipoprotein (ox-LDL) and nitrite/nitrate (NOx) levels in CAD patients has not been evaluated. Therefore, we sought to evaluate these relationships. Materials & methods: This study included 50 stable CAD patients, 50 unstable CAD patients and 50 control subjects. Plasma MPO and ox-LDL levels were determined using enzyme immunoassay. Plasma NOx and other risk factors were also measured in the patients. Results: Plasma MPO levels were higher in unstable CAD patients (71.2 +/- 19.6 ng/ml) than in stable CAD patients (34.5 +/- 6.8 ng/ml) and control subjects (23.0 +/- 3.6 ng/ml) (p < 0.001). Furthermore, plasma MPO was positively correlated with ox-LDL and negatively correlated with NOx levels (p < 0.05). Conclusion: Plasma MPO levels were elevated in CAD patients and its relation to CAD may be through the oxidation of LDL and reduction of NO levels.