Genetic insights into causal effects of lipids and lipid-modifying targets on calcific aortic valve stenosis: a Mendelian randomized study

Calcific aortic valve stenosis (CAVS) is steadily rising worldwide with no effective pharmacological agents available. Observational studies implicated dyslipidaemia as a risk factor for CAVS. Whether dyslipidaemia is causative for CAVS and the therapeutic potential of different lipid-modifying drug targets for CAVS treatment remains unclear. We appraised the relationship of genetically-proxied lipid traits and 12 lipid-modifying drug targets with CAVS risk using Mendelian randomization (MR). Genetic variants associated with lipid traits and variants in genes encoding lipid-modifying drug targets were retrieved from GLGC. Summary-level data for CAVS were obtained from the TARGET consortium and FinnGen. Validation analyses were performed using genetic instruments retrieved from liver-derived gene expression and circulation plasma levels of targets. Colocalisation and mediation analyses were performed to evaluate the robustness of our findings and explore potential mediators (i.e., lipoprotein a (Lp(a)), body mass index, apolipoprotein B (ApoB)). The MR analyses supported that total cholesterol and LDL-cholesterol level were independent causal risk factors. The drug-target MR analysis suggested that genetic mimicry of PCSK9 inhibition should reduce CAVS risk (OR = 0.63, 95% CI = 0.56-0.70), which was corroborated by colocalisation analysis. Secondary analyses supported a genetically proxied effect of liver-specific PCSK9 expression (OR = 0.94 per SD reduction in PCSK9 expression, 95% CI = 0.88-1.00) and circulating plasma levels of PCSK9 (OR = 0.86 per SD reduction in PCSK9 protein, 95% CI = 0.83-0.88) on CAVS risk. ApoB and Lp(a) mediated 55.9% and 4.5%, respectively, of the total effect of PCSK9 on CAVS risk. Multiple sensitivity analyses supported this observation. Our study supports total cholesterol, LDL-cholesterol as a causal factor for CAVS, and genetically proxied inhibition of PCSK9 may reduced its risk.