Background

Many patients still face a risk of myocardial infarction or stroke even when low-density lipoprotein cholesterol (LDL-C) is adequately reduced. This review highlights lipoprotein(a), or Lp(a), as a key contributor to residual cardiovascular risk, critically evaluating the evidence and therapeutic strategies.

Lp(a) is a lipoprotein particle similar to LDL with apolipoprotein(a) bound to it. Its plasma concentration is largely determined by the LPA gene and is difficult to modify through diet or exercise. It independently promotes atherosclerosis, inflammation, thrombosis, and tissue calcification. Elevated Lp(a) is associated not only with coronary artery disease and stroke but also with peripheral arterial disease, calcific aortic valve disease, heart failure, and abdominal aortic aneurysm.

The issue is that existing lipid-lowering therapies, including statins, have little effect on reducing Lp(a). Even when patients achieve LDL-C targets, high Lp(a) leaves a separate risk axis. Observational and genetic studies largely support a causal role for Lp(a), though results are not entirely consistent. The magnitude of risk and therapeutic benefit may differ between primary prevention groups without cardiovascular disease and secondary prevention groups who have already experienced an event.

Key Findings

The researchers evaluated Lp(a) not merely as a risk marker but as a directly modifiable therapeutic target. The most advanced approaches include antisense oligonucleotides (ASO) and small interfering RNA (siRNA) therapies that inhibit apolipoprotein(a) synthesis in the liver. ASO binds to LPA messenger RNA to block protein translation, while siRNA uses RNA-induced silencing complexes to degrade the message. Both strategies target Lp(a) production itself rather than downstream effects of the disease.

CETP inhibitors are also among the candidates. This class alters multiple lipoprotein fractions, offering lower selectivity for Lp(a) compared to nucleic acid therapies, but they are orally administered and provide broader lipid improvements. Experimental gene-editing strategies that directly inactivate the LPA gene aim for long-term efficacy, but safety concerns remain, including off-target mutations and long-term monitoring challenges due to the irreversible nature of the edits.

The novel drug candidates reviewed in the review reduced plasma Lp(a) by up to approximately 90%, a change difficult to achieve with existing lipid-lowering therapies. However, this numerical reduction is a surrogate endpoint. The value of Lp(a) as a therapeutic target can only be confirmed when ongoing phase III trials demonstrate a reduction in actual clinical events such as myocardial infarction, stroke, and cardiovascular death.

Implications and Outlook

The success of Lp(a) therapies could shift cardiovascular prevention strategies from a single-axis focus on LDL-C to a multi-factorial risk management approach. Patients who experience recurrent events despite optimal statin, ezetimibe, and PCSK9 inhibitor therapy, or those with a family history of early cardiovascular disease who lack a clear explanation from standard tests, are likely to be the initial target population.

Before clinical adoption, several issues remain. Lp(a) is measured in both mass concentration (mg/dL) and particle concentration (nmol/L), but due to the variable size of apolipoprotein(a) among individuals, these units cannot be accurately converted using a fixed coefficient. Standardization of testing methods, risk thresholds for different ethnic and population groups, and criteria for initiating treatment are needed. It is also unclear at what level of reduction clinical benefit is achieved, and whether costly injectable therapies are cost-effective in primary prevention.

Most importantly, this paper is a review evaluating existing observational, genetic, and interventional studies rather than presenting new clinical trial results. A biochemical achievement of up to 90% reduction does not immediately translate into survival benefit for patients. If phase III trials confirm a reduction in cardiovascular events, Lp(a) will transition from a "hidden risk factor" measured in isolation to a preventive indicator linked to screening and targeted therapy.