What is Lipoprotein(a)?
Lipoprotein(a), or Lp(a), is a genetically-determined cholesterol-rich particle composed of an LDL-like particle covalently bound to apolipoprotein(a), and it is a causal, independent risk factor for cardiovascular disease and calcific aortic valve stenosis that affects 20-30% of the global population. 1
Structure and Genetics
Lp(a) consists of an apolipoprotein B-containing LDL-like particle attached to apolipoprotein(a), which has structural similarity to plasminogen but lacks fibrinolytic activity 2. Your Lp(a) levels are primarily determined by the LPA gene and remain essentially constant throughout your lifetime, unaffected by diet or lifestyle modifications 1, 2. The particle contains approximately 30-45% cholesterol by mass, which is measured as part of your "LDL-C" laboratory value 1.
Clinical Significance
Risk Thresholds
The evidence shows varying thresholds depending on the guideline:
- Traditional threshold: >30 mg/dL (>75 nmol/L) represents the 75th percentile in white populations and marks increased CVD risk 1
- European guidelines: >50 mg/dL (~100-125 nmol/L) represents the 80th percentile and significant risk 1
- Most recent NLA guidance (2024): Stratifies risk as low (<75 nmol/L or <30 mg/dL), intermediate (75-125 nmol/L or 30-50 mg/dL), and high (≥125 nmol/L or ≥50 mg/dL) 3
Disease Associations
Lp(a) causes cardiovascular disease through three mechanisms 4:
- Atherosclerosis promotion: Cholesterol deposition in arterial intima
- Thrombogenicity: Prothrombotic and antifibrinolytic effects due to plasminogen-like structure
- Inflammation: Proinflammatory effects and vascular calcification
Critically, elevated Lp(a) confers residual cardiovascular risk even when LDL cholesterol is optimally controlled 5. This means patients can have perfect LDL-C levels and still experience cardiovascular events if Lp(a) is elevated.
Who Should Be Tested
The 2024 NLA update recommends measuring Lp(a) at least once in every adult for risk stratification 3. This represents a significant shift toward universal screening.
Priority groups for testing include 1, 6:
- Premature CVD or stroke without other evident risk factors
- Familial hypercholesterolemia
- Family history of premature CVD or elevated Lp(a)
- Recurrent or rapidly progressive vascular disease despite optimal lipid therapy
- Intermediate cardiovascular risk by traditional risk scores (to reclassify into higher risk category)
- Patients with ≥3% 10-year risk of fatal CVD
Cascade screening of first-degree relatives is recommended when elevated Lp(a) is identified 3.
Management Approach
Primary Strategy: Aggressive LDL-C Reduction
When Lp(a) is elevated, the most important intervention is intensive treatment of modifiable risk factors, especially LDL cholesterol 6. This is because:
- Elevated Lp(a) amplifies the risk from other lipid abnormalities
- Patients with both elevated Lp(a) and LDL-C have 10-fold or higher MI risk 6
- The cholesterol content of Lp(a) contributes to total atherogenic burden
Current Treatment Limitations
Standard lipid therapies are largely ineffective for Lp(a) reduction 5:
- Statins: May actually increase Lp(a) levels 6
- Ezetimibe: No significant effect
- Lifestyle modification: Ineffective 5
- PCSK9 inhibitors: Modest reduction (20-30%) 6
- Niacin: 30-35% reduction but unclear cardiovascular benefit and adverse effects 6, 5
Specialized Therapies
LDL/Lp(a) apheresis is FDA-approved for high-risk patients with familial hypercholesterolemia and documented coronary or peripheral artery disease whose Lp(a) remains ≥60 mg/dL (~150 nmol/L) and LDL-C ≥100 mg/dL on maximally tolerated therapy 3. Apheresis can reduce Lp(a) by up to 80% 6.
Emerging Therapies
Novel RNA-based therapies show the most promise, achieving >90-95% Lp(a) reduction 7:
- Pelacarsen: Antisense oligonucleotide
- Olpasiran: Small interfering RNA
- SLN360: Small interfering RNA
These agents specifically target hepatic LPA gene expression and are administered monthly via subcutaneous injection 7. Phase 3 trials are ongoing to determine if these dramatic Lp(a) reductions translate to cardiovascular benefit 5.
Key Clinical Pitfalls
- Don't assume normal LDL-C means low cardiovascular risk - elevated Lp(a) confers independent risk
- Don't expect lifestyle changes to lower Lp(a) - it's genetically determined
- Don't use statins expecting Lp(a) reduction - they may increase it
- Remember that Lp(a) cholesterol is included in measured LDL-C - in patients with very low LDL-C on therapy, a substantial portion may be from Lp(a) 1
- Screen family members - Lp(a) is inherited and cascade screening identifies additional at-risk individuals 3