Background: This study was performed to assess whether oxidized low-density lipoprotein (OxLDL) levels are elevated after percutaneous coronary intervention (PCI).
Methods and results: Patients (n=141) with stable angina pectoris undergoing PCI had serial venous blood samples drawn before PCI, after PCI, and at 6 and 24 hours, 3 days, 1 week, and 1, 3, and 6 months. Plasma levels of OxLDL-E06, a measure of oxidized phospholipid (OxPL) content on apolipoprotein B-100 detected by antibody E06, lipoprotein(a) [Lp(a)], autoantibodies to malondialdehyde (MDA)-LDL and copper-oxidized LDL (Cu-OxLDL), and apolipoprotein B-100-immune complexes (apoB-IC) were measured. OxLDL-E06 and Lp(a) levels significantly increased immediately after PCI by 36% (P<0.0001) and 64% (P<0.0001), respectively, and returned to baseline by 6 hours. In vitro immunoprecipitation of Lp(a) from selected plasma samples showed that almost all of the OxPL detected by E06 was bound to Lp(a) at all time points, except in the post-PCI sample, suggesting independent release and subsequent reassociation of OxPL with Lp(a) by 6 hours. Strong correlations were noted between OxLDL-E06 and Lp(a) (r=0.68, P<0.0001). MDA-LDL and Cu-OxLDL autoantibodies decreased, whereas apoB-IC levels increased after PCI, but both returned to baseline by 6 hours. Subsequently, IgM autoantibodies increased and peaked at 1 month and then returned to baseline, whereas IgG autoantibodies increased steadily over 6 months.
Conclusions: PCI results in acute plasma increases of Lp(a) and OxPL and results in short-term and long-term immunologic responses to OxLDL. OxPL that are released or generated during PCI are transferred to Lp(a), suggesting that Lp(a) may contribute acutely to a protective innate immune response. In settings of enhanced oxidative stress and chronically elevated Lp(a) levels, the atherogenicity of Lp(a) may stem from its capacity as a carrier of proinflammatory oxidation byproducts.