Abstract

Background: High density lipoproteins are all heterogeneous population of particles. Two main subpopulations have been identified, one contains Apo A-I and APo A-II and is denominated LPA-I:A-II and another one contains only, Apo A-I and is denominated LPA-I. Aim: To measure the concentrations of these particles in patients with stable coronary artery disease. Patients and Methods: Serum lipids, A-I and B apolipoproteins, LpA- I, LPA-I. A-I and LPB particles were measured in 73 melt aged 33 to 82 years with angiographically documented coronary artery disease (CAD) and 33 control subjects aged 39 to 76 years. LPA-I, LPA-I. A-II and LpB were measured by a noncompetitive enzyme linked immunoassay using previously characterized monoclonal antibodies against Apo A-I, APoA-II and apoB. Results: Patients with CAD had significantly higher mean levels of LDL cholesterol than the control group (p=0.038). The mean concentration of LPA-I particles in patients with CAD was significantly lower (p=0.031) than in control subjects, while the concentration of LpA-I:A-II particles was significantly, higher (p=0.016). The percentage of coronary stenosis correlated negatively with LPA-I and positively with LPA-I:A-II. The best relative risk (RR) indicator in these patients was LDL-cholesterol. The relative risk increases 2.5 fold when LPA-I falls below the cut-off level. Likewise, the relative risk increases 3-fold when LPA-I:A-II raises over the cut-off level. Conclusions: Our findings indicate that the quantification of LPA-I and LPA-I:A-II particles might allow, a more accurate evaluation of the CAD risk than HDL cholesterol. LPA-I might represent the antiatherogenic fraction of HDL.