Lipoprotein(a) cardiovascular disease risk not captured by low density lipoprotein cholesterol and apolipoprotein B

Abstract Background Elevated lipoprotein(a) affects 1 in 5 individuals and is considered a causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and aortic valve stenosis (AVS). However, lipoprotein(a) measurements are not widely implemented in clinical practice. Low-density lipoprotein (LDL) cholesterol and apolipoprotein B (ApoB) measurements include contributions from lipoprotein(a), yet whether these measurements can replace measurements of lipoprotein(a) in assessing cardiovascular disease risk from this causal risk factor is unknown. Purpose We tested the hypotheses that lipoprotein(a) risk of ASCVD and AVS is captured by LDL cholesterol or ApoB. Methods We included 70,189 individuals from a prospective contemporary cohort study of the general population. Mediated risk by LDL cholesterol and ApoB in the association between lipoprotein(a) and risk of ASCVD and AVS was examined using four-way decomposition analyses stratified by statin treatment at baseline. Results During a median follow-up of 10.8 years, 7,127 developed ASCVD and 1,516 AVS. Per 50 mg/dL higher lipoprotein(a), multivariable adjusted hazard ratios were 1.22 (95% CI: 1.18-1.26) for ASCVD and 1.36 (1.28-1.46) for AVS. In individuals without statin use, LDL cholesterol mediated 19% (15%-24%) of the risk of ASCVD from lipoprotein(a) and 7.7% (1.5%-14%) of the risk of AVS from lipoprotein(a) (Figure 1). Corresponding values for ApoB were 14.0% (11%-18%) and 6.6% (2.8%-10%). In statin users (n=9,570), LDL cholesterol did not mediate risk of ASCVD from lipoprotein(a) but mediated 8.0% (0.8%-15%) of the risk of AVS from lipoprotein(a). Correspondingly, ApoB mediated 9.8% (2.2%-17%) of the risk of ASCVD and 4.2% (0.4%-8.0%) of the risk of AVS from lipoprotein(a). Conclusion Lipoprotein(a) risk of ASCVD and AVS is not adequately captured by LDL cholesterol and ApoB. Therefore, lipoprotein(a) measurement is needed in all individuals to capture the cardiovascular disease risk from this causal risk factor.