OBJECTIVETo investigate the changes of neutrophil myeloperoxidase (MPO) blood concentration gradient between the systemic circulation and the coronary circulation among patients with acute coronary syndrome and its clinical value.

METHODSFifty patients underwent coronary angiography, which including 10 patients in AMI group, 20 patients in UA group, 10 patients in SA group and 10 subjects served as control. The levels of MPO and hs-CRP were measured in the serum of blood collected from femoral vein, aortic artery root and coronary sinus.

RESULTSCompared with the control, concentrations of LDL in the AMI, UA and SA groups were significantly increased, while the latter three groups did not differ from each other. In the UA patients, the in-gate percentage of MPO decreased in the coronary sinus compared with that in the root of aortic artery (P < 0.01); the in-gate percentage of MPO decreased through coronary circulation more than through systemic circulation (P < 0.001); the average fluorescent intensity of MPO and the concentrations of hs-CRP showed no difference between samples from the coronary sinus and that from the root of aortic artery. In the AMI patients, the average fluorescent intensity of MPO in the coronary sinus was weakened compared with that in the root of aortic artery (P < 0.05); it decreased through coronary circulation more than through systemic circulation (P < 0.001); neither the in-gate percentage of MPO nor the concentrations of hs-CRP showed significant difference between samples from the coronary sinus and that from the root of aortic artery. In the control and SA groups, samples from the femoral vein, the root of aortic artery, and the coronary sinus did not show differences at the serum level of MPO and hs-CRP. In the UA group, the in-gate percentage of MPO correlated positively with the concentration of hs-CRP (r = 0.78, P < 0.01), and with the level of LDL as well (r = 0.52, P < 0.05); In the AMI group, the average fluorescent intensity of MPO correlated negatively with the concentration of hs-CRP (r = -0.80, P < 0.01), and showed no correlation with the level of LDL (r = 0.22, P > 0.05).

CONCLUSIONSMPO is a better marker for inflammation of the local plaques. It may be one of the mechanisms that MPO induces the transforming from LDL to ox-LDL in plaques vulnerability.