Medical Journal of The Islamic Republic of Iran (MJIRI)

  Abstract

  Background: Recently, small dense low density lipoprotein (sdLDL) has been

  highlighted as a new risk factor for the coronary artery disease (CAD).Small dense

  LDLs are believed to be atherogenic since these particles are taken up more easily by

  arterial wall. They are readily oxidized and have reduced affinity for low density

  lipoprotein (LDL) receptor and increased affinity for arterial proteoglicans. LDL

  cholesterol is only a measure of the cholesterol level in the LDL whereas apolipoprotein

  B(apo B) is a measure of the cholesterol levels of all the atherogenic particles, including

  very low density lipoprotein, intermediate density, and low density lipoproteins.

  Therefore, it might be a better marker than other traditional lipids. The aim of

  the present study was to evaluate the association between serum small dense LDL,

  apolipoprotein B, apolipoprotein A1 (apo A1) and apoB/apoA1 ratio and the coronary

  stenosis.

  Methods: 86 patients with coronary stenosis , 35 patients without coronary stenosis

  identified by angiography who were referred to Rajaii Heart Center , and 30

  healthy individuals were studied. SdLDL was measured by a direct homogenous

  LDL-C assay in the supernatant of serum which remained after heparin-magnesium

  precipitation. Serum apolipoprotein A1 and apolipoprotein B were measured by using

  immunoturbidimetric method.

  Results: The results showed that the sdLDL levels were higher in patients with

  coronary stenosis than patients without coronary stenosis and healthy individuals

  (21.54±7.1, 16.88±4.4 and 15.45±5mg/dl, p=0.001, respectively). In addition the level

  of apoB (with stenosis: 113.71±21.8, without stenosis:100.88±18.7 and healthy:

  102.30±9.6, p=0.003) and apoB/apoA1 ratio (with stenosis:1.100±0.24, without

  stenosis :0.589±0.26 and healthy:0.751±0.16, p=0.001) were significantly higher in

  patients with coronary stenosis. SdLDL levels were positively correlated with the

  level of apoB(r=0.589), apoB/apoA1 ratio(r=0.416), triglyceride(r=0.494), LDL-C

  (r=0.749), Total cholesterol(r=0.354) and were inversely correlated with the level of

  HDL-C (r = -0.586)(p<0.01).

  Conclusion: The elevated levels of small dense LDL, apoB and apoB/apoA1 ratio

  were associated with coronary artery stenosis.