Effect of APOE ε Genotype on Lipoprotein(a) and the Associated Risk of Myocardial Infarction and Aortic Valve Stenosis

Context APOE ε2/3/4 genotypes affect plasma lipoprotein(a); however, the effects of APOE genotypes on the prediction of myocardial infarction and aortic valve stenosis by lipoprotein(a) are unknown. Objective We tested the hypothesis that APOEε2/3/4 genotype affects plasma lipoprotein(a), the contribution of plasma apoE levels to this association as well as the associated risk of myocardial infarction and aortic valve stenosis. Design and Outcome Measures In 46,615 individuals from the general population, we examined plasma lipoprotein(a), APOE ε2/3/4, and incidence of myocardial infarction (n = 1807) and aortic valve stenosis (n = 345) over 37 years of follow-up (range: 0.3 to 38 years). Results Compared with ε33, age- and sex-adjusted lipoprotein(a) concentrations were lower by 15% in ε23, by 24% in ε24, and by 36% in ε22; adjusted for plasma apolipoprotein E, corresponding values were 22%, 28%, and 62%. These reductions were independent of LPA genotypes. Compared with ε2 carriers with lipoprotein(a) ≤50 mg/dL, the hazard ratio for myocardial infarction was 1.26 (95% confidence interval: 1.06 to 1.49) for ε2 noncarriers with lipoprotein(a) ≤50 mg/dL, 1.68 (1.21 to 2.32) for ε2 carriers with lipoprotein(a) >50 mg/dL, and 1.92 (1.59 to 2.32) for ε2 noncarriers with lipoprotein(a) >50 mg/dL (interaction, P = 0.57); corresponding values for aortic valve stenosis were 1.05 (0.74 to 1.51), 1.49 (0.72 to 3.08), and 2.04 (1.46 to 2.26) (interaction, P = 0.50). Further adjustment for APOE ε2/3/4 genotype had minimal influence on these risk estimates. Conclusions APOE ε2 is a strong genetic determinant of low lipoprotein(a) concentrations but does not modify the causal association of lipoprotein(a) with myocardial infarction or aortic valve stenosis.