Antibodies to oxidized low-density lipoprotein in patients following coronary artery revascularization

Measurement of antibodies to oxidized low-density lipoprotein (AB-oxLDL) has been proposed as a way of identifying individuals at risk for cardiovascular disease beyond the determination of LDL cholesterol (LDL-c) alone. While this hypothesis is appealing, evidence that AB-oxLDL is a risk factor independent of LDL-c levels remains to be established.

We conducted a cross-sectional study of 158 hypercholesterolemic adults who underwent coronary revascularization. Patients were randomized in a clinical trial to a nurse case management (NURS) or an enhanced usual care (EUC) group. The goal in the NURS group was to achieve an LDL-c <85 mg/dl with pharmacotherapy and lifestyle advice. Six months after revascularization, serum and urine were collected to determine lipids, AB-oxLDL, urinary isoprostanes (an in-vivo marker of oxidative damage), oxygen-radical-absorbing capacity (ORAC) of serum, serum carotenoids, alpha-tocopherol and C-reactive protein (CRP). After 6 months of intervention, the NURS group had a mean (+/-SD) LDL-c of 84 (18) mg/dl compared with 105 (25) mg/dl in the EUC group (P < 0.001). In addition, AB-oxLDL was lower (median +/- 95% confidence interval, -202 milliunits (mU)/ml, -372 to -32, P = 0.02) in the NURS group (488 mU/ml, 399, 588) than in the EUC group (690 mU/ml, 544, 847). The difference in AB-oxLDL between groups persisted after adjustment for LDL-c (-316 mU/ml, -519 to -112, P = 0.005). Further adjustment for ORAC and alpha-tocopherol did not diminish the group effect. The groups did not differ significantly in serum antioxidants, urinary isoprostane excretion or CRP. In additional analyses, change in LDL-c from baseline was not associated with AB-oxLDL at 6 months.

Our results demonstrate lower AB-oxLDL in patients who achieve greater lipid reduction. However, AB-oxLDL appears to be independent of achieved LDL-c, ORAC levels or serum antioxidant levels. These results support the hypothesis that AB-oxLDL is independent of LDL-c level. Further prospective studies are needed to determine the prognostic value of AB-oxLDL.