#210 - Lp(a) and its impact on heart disease | Benoît Arsenault, Ph.D.

Episode Summary

Executive Summary: Peter Attia and Benoit Arsenault discuss lipoprotein(a) [Lp(a)] as a common, largely genetic, and under-tested driver of ASCVD and aortic stenosis. They review its biology, measurement challenges, inheritance, disease associations, why statins don’t meaningfully lower it, why PCSK9 inhibitors lower it modestly, and why antisense/siRNA therapies may finally enable targeted treatment.

Main Topics: What Lp(a) is and why it matters (Priority: 5/5): Lp(a) is an LDL-like particle with apolipoprotein(a) attached; it is a major inherited risk factor for atherosclerotic cardiovascular disease and aortic stenosis, and many patients remain undiagnosed because it is rarely measured. Epidemiology, inheritance, and measurement (Priority: 5/5): Lp(a) varies by ethnicity, is highly heritable, and is best measured once in a lifetime using nmol/L assays rather than mg/dL because isoform size distorts mass-based results. Biology and pathophysiology (Priority: 5/5): The discussion covers hepatic production, kringle repeats, covalent binding to ApoB100, oxidized phospholipids, plasminogen homology, and how these features may drive inflammation, thrombosis, and calcification. Clinical disease associations (Priority: 5/5): Lp(a) is linked most strongly to aortic stenosis, then PAD, MI, ischemic stroke, and CKD; it appears to contribute to both initiation and progression of vascular and valvular disease. Therapies and why some fail (Priority: 4/5): Statins do not lower Lp(a) and may slightly raise it; niacin lowers Lp(a) modestly but has not improved outcomes; PCSK9 inhibitors lower Lp(a) about 25-30% but are not sufficient as a dedicated Lp(a) therapy. Emerging targeted treatments (Priority: 5/5): Antisense oligonucleotides and siRNA therapies targeting LPA are the most promising future treatments, with phase 2 data showing large reductions and phase 3 outcomes trials underway. Risk management while awaiting Lp(a)-specific drugs (Priority: 4/5): Until targeted therapies arrive, the strategy is aggressive ApoB lowering plus control of all modifiable risk factors, and consideration of imaging for aortic valve disease in high-risk patients.

Key Arguments: Lp(a) is a causal, genetically driven risk factor for ASCVD independent of LDL, supported by both improved epidemiology and Mendelian randomization. The number of Lp(a) particles matters more than apo(a) isoform size; isoform size mainly influences risk through its effect on circulating Lp(a) concentration. Mass-based Lp(a) assays can mislead because apo(a) isoform size changes the measured mass; nmol/L better reflects particle number. Statins are still beneficial in patients with high Lp(a) because ApoB lowering outweighs any small Lp(a) increase. Niacin lowers Lp(a) and improves lipid panels, but large outcome trials failed to show cardiovascular benefit and side effects limit use. PCSK9 inhibitors lower Lp(a) modestly and are useful for ApoB reduction, but they do not adequately neutralize Lp(a)-driven residual risk. Aortic stenosis is one of the strongest clinical manifestations of Lp(a), and early detection matters because earlier intervention improves outcomes. Future LPA-targeting antisense/siRNA drugs may finally provide the magnitude of Lp(a) lowering needed to affect outcomes.

Data Points: Global prevalence of high Lp(a): ~20% of the world population - Benoit estimates the share of people in a higher-risk Lp(a) category, varying by ethnicity. High Lp(a) in African ancestry: Highest levels among ethnic groups - Discussed as having the highest Lp(a) levels, even after adjustment for isoform size. High Lp(a) in East Asian ancestry: Lower levels than African ancestry - Chinese and Japanese populations were described as having among the lowest levels. Discovery year: 1963 - Lp(a) was discovered by Swedish scientist Kåre Berg. Early genetic association studies: 2009-2011 - GWAS and genetic studies revived the field after earlier negative observational studies. TNT biomarker panel: 18 biomarkers - Lp(a) was the strongest predictor of residual cardiovascular risk among a large biomarker panel in the TNT trial analysis. Procardis study size: ~3,000 cases and 3,000 controls - One of the first 2009 genetic studies linking LPA variants to heart disease. LPA-raising alleles: Dose-response effect - More LPA-raising variants corresponded to higher Lp(a) and higher heart disease risk. Isoform repeats: Up to 40 kringle 4 type 2 repeats - Variation in kringle 4 type 2 drives apo(a) isoform size heterogeneity. Kringle 4 type 2 copy number variation: 1 to ~40 repeats - Explains much of the size variability in apo(a). Statin effect on Lp(a): 0% to ~10% increase - Statins generally do not lower Lp(a) and may slightly raise it in some studies. Niacin Lp(a) reduction: ~20-30% - Average reduction discussed, though not linked to outcome benefit. PCSK9 inhibitor Lp(a) reduction: ~25-30% on average - Observed across studies, with substantial variability. High Lp(a) threshold example: 50 mg/dL ≈ 125 nmol/L - Used repeatedly as a practical high-risk reference point. Very high Lp(a) case example: 690 nmol/L - Peter described a patient with extremely high Lp(a) and zero calcium score in their 40s. Another case example: 1800 nmol/L LDL particle concentration with 690 nmol/L Lp(a) - Illustrated that Lp(a) can comprise a large fraction of ApoB particles. Aortic stenosis risk increase: ~50% to 100% or more - For moderately elevated Lp(a), risk may rise by 50-100%; higher levels confer substantially more risk. Aortic stenosis prevalence in older adults: ~2% over age 60 - Used to explain why absolute risk is lower than relative risk despite strong association. ApoB target used clinically: 30-40 mg/dL - Peter described targeting physiologic ApoB levels in high Lp(a) patients. Lp(a) reduction needed for benefit: ~50-100 mg/dL lifelong reduction - Mendelian randomization estimates suggested a large and sustained reduction may be needed for outcome benefit. Phase 2 antisense reduction: ~80% mean reduction - Ionis compound in phase 2 showed large Lp(a) lowering at the intended monthly dose. Patients below threshold on antisense: 90% below 50 mg/dL - At the phase 2 dose, most treated patients reached below the high-risk threshold. Horizon trial size: ~8,000 patients - Secondary prevention outcomes trial of LPA antisense therapy. Horizon duration: ~4 years - Longer treatment period intended to compensate for smaller sample size. EPIC-Norfolk cohort: 18,000 individuals - Used to study how Lp(a) interacts with Life’s Simple 7 risk factors. Risk reduction with optimal risk-factor control: ~two-thirds lower risk - Observationally, high Lp(a) patients who controlled major risk factors had much lower event risk. PCSK9 outcomes trial timing: ~2.2 to 2.4 years - FOURIER and ODYSSEY showed benefit earlier than expected despite low starting LDL. PCSK9 outcomes benefit: ~15% relative risk reduction - Discussed as a meaningful result given already-low baseline LDL and short follow-up.

Pivotal Quotes: "Lp little a is the single highest genetically inherited trait that confers high risk of ASCVD." — Peter Atiyah: Peter frames the clinical importance of Lp(a) early in the episode. "So the most important thing is the number of oxidized phospholipids that are transported by lipoprotein little a, which is much higher than the amount of oxidized phospholipids that you see on LDL particles." — Benoit Arsenault: Explaining why Lp(a) is more atherogenic than LDL on a particle-for-particle basis. "It’s really the LPA number that matters and not necessarily the isoform size." — Benoit Arsenault: Summarizing the modern consensus on what drives risk.

Implications: Lp(a) should be measured at least once, especially in people with premature ASCVD or aortic stenosis. Until targeted drugs arrive, the best strategy is aggressive ApoB lowering and full risk-factor control; phase 3 LPA therapies could soon change practice.