The goal of this study was to examine the association between paraoxonase-1 (PON1) activity and concentration and the severity and extent of coronary artery disease (CAD).

Paraoxonase-1, a high-density lipoprotein-associated enzyme, is proposed to have an antiatherogenic effect by protecting low-density lipoproteins against oxidation.

We studied PON1 activity and concentration in 107 patients with known or suspected CAD referred for cardiac catheterization. Based on visual estimation of coronary angiograms, subjects were classified as having no or mild CAD (<50% stenosis) and significant CAD (≥50% stenosis). Quantitative coronary angiography (QCA) was used to estimate the indexes of severity, extent, and overall atheroma burden of CAD.

We found lower values of PON1 activity and concentration (p = 0.003 and p = 0.016, respectively) in the group with significant CAD as compared with the group with no or mild CAD. The PON1 activity was significantly inversely correlated with CAD severity (r = −0.364, p < 0.001), extent (r = −0.221, p = 0.022), and atheroma burden (r = −0.277, p = 0.004). Similarly, PON1 concentration correlated with CAD severity (r = −0.306, p = 0.001) and atheroma burden (r = −0.229, p = 0.017). In multiple regression analysis, gender and PON1 activity were significant determinants of the severity of CAD independently of age, hypertension, smoking, abnormal glucose regulation, and high-density lipoprotein cholesterol.

Our results indicate that PON1 activity and concentration are lower in subjects with significant CAD, and that there is a significant relationship between PON1 activity and concentration and CAD assessed by QCA.