Genetics hints that lowering both Lp(a) and LDL may cut heart risk more

Two blood lipids drive atherosclerosis by partly different routes: LDL cholesterol, the target of statins and newer drugs, and lipoprotein(a) — Lp(a) — a largely genetically fixed particle that a first wave of dedicated therapies is now trying to lower. A study published on 3 September in Nature Cardiovascular Research uses human genetics to ask a question the clinical trials have not yet answered: does going after both at once add up to more benefit than going after either alone [s1]?

Borrowing the body's own experiment

The design is a form of Mendelian randomisation. Because gene variants are allocated randomly at conception, people who inherit a variant that lowers a lipid for life resemble the arms of a very long, natural trial — free of the confounding that dogs ordinary observational studies. The authors used coding loss-of-function variants in LPA (which lower Lp(a)) and PCSK9 (which lower LDL cholesterol), plus genetic scores tied to each lipid's level, to estimate the effect of lowering one, the other, or both on coronary artery disease [s1].

They drew on 408,039 individuals from the UK Biobank [s1].

What the genetics showed

Carriers of a loss-of-function variant in either gene had lower coronary disease risk than non-carriers — an odds ratio of 0.91 for LPA carriers and 0.81 for PCSK9 carriers [s1]. People who carried loss-of-function variants in both genes had lower risk still, with an odds ratio of 0.73 [s1].

The genetic-score analysis pointed the same way. Genetically lower Lp(a) and lower LDL cholesterol together were associated with a stronger reduction in coronary disease risk (odds ratio, 0.70) than either trait individually (0.85 for Lp(a) and 0.81 for LDL cholesterol) [s1]. Among statin users, lower Lp(a) was linearly associated with lower risk — suggesting the Lp(a) benefit stacks on top of LDL lowering rather than overlapping with it [s1]. A phenome-wide scan found the combined genetic profile was linked to cardiometabolic benefits without evident adverse effects, and the additive pattern was replicated in 65,171 people from the Mass General Brigham Biobank [s1].

What this is and is not

This is genetic evidence about lifelong exposure, not a trial of drugs. It builds a strong biological rationale that combining an Lp(a)-lowering agent with an LDL-lowering one could yield additive cardiovascular benefit — but inheriting a low lipid level from birth is not the same as lowering it with a medicine started in middle age, and Mendelian randomisation cannot capture the timing, dose or side-effect profile of an actual therapy. The absence of adverse signals in a genetic scan is reassuring but not equivalent to a drug-safety result.

The distinction matters right now because Lp(a)-lowering drugs are in late-stage testing, and this paper is exactly the kind of evidence used to justify — and to design — the outcome trials that will decide whether the combination earns a place in practice. Those trials, not this analysis, are what would change treatment.

What to watch

The open question is whether adding an Lp(a)-lowering agent to established LDL-lowering therapy delivers, in a randomised outcome trial, the additive benefit the genetics predicts — and at what cost and safety profile. Until then, the finding sharpens the hypothesis rather than settling it.

This article is informational and does not constitute medical advice.