Evolving lipoprotein risk factors: lipoprotein(a) and oxidized low-density lipoprotein.

Cardiovascular disease is the leading cause of morbidity and mortality in Westernized populations. Evolving lipoprotein risk factors include LDL oxidation and lipoprotein(a) [lp(a)]. Several lines of evidence support a role for oxidatively modified LDL in atherogenesis and its in vivo existence. There are both direct and indirect measures of oxidative stress. The most relevant direct measure of lipid peroxidation is urinary F2 isoprostanes. The most common indirect measure of LDL oxidation is quantifying the lag phase of copper-catalyzed LDL oxidation by assaying conjugated diene formation. Lp(a) is increased in patients with cardiovascular and cerebrovascular disease. However, not all prospective studies have confirmed a positive relationship between Lp(a) and cardiovascular events. Lp(a) appears to present three major problems: standardization of the assay, establishing its role in atherogenesis, and the lack of an effective therapy that can substantially lower Lp(a) concentrations. Thus, at the present time, Lp(a) concentrations should not be recommended for the general population but be reserved for patients with coronary artery disease without established risk factors, young patients with coronary artery disease or cerebrovascular disease, or a family history of premature atherosclerosis and family members of an index patient with increased concentrations of Lp(a). Although both LDL oxidation and Lp(a) are evolving risk factors for cardiovascular disease, more data are needed before they become part of the established lipoprotein repertoire.