Lipoprotein(a) Levels, Genotype, and Incident Aortic Valve Stenosis: A Prospective Mendelian Randomization Study and Replication in a Case–Control Cohort

Considerations for routinely testing for high Lp(a)

PURPOSE OF REVIEW

Lipoprotein(a) (Lp[a]) is a likely causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and aortic valve disease, confirmed by Mendelian randomization. With reliable assays, it has been established that Lp(a) is linearly associated with ASCVD. Current low-density lipoprotein cholesterol (LDL-C) lowering therapies do not or minimally lower Lp(a). This review focuses on the clinical importance and therapeutic consequences of Lp(a) measurement.

RECENT FINDINGS

Development of RNA-based Lp(a) lowering therapeutics has positioned Lp(a) as one of the principal residual risk factors to target in the battle against lipid-driven ASCVD risk. Pelacarsen, which is a liver-specific antisense oligonucleotide, has shown Lp(a) reductions up to 90% and its phase 3 trial is currently underway. Olpasiran is a small interfering RNA targeting LPA messenger RNA which is being investigated in phase 2 and has already shown dose-dependent Lp(a) reductions up to 90%.

SUMMARY

Lp(a) should be measured in every patient at least once to identify patients with very high Lp(a) levels. These patients could benefit from Lp(a) lowering therapies when approved. In the meantime, therapy in high Lp(a) patients should focus on further reducing LDL-C and other ASCVD risk factors.

Lipoprotein(a) and cardiovascular and valvular diseases: A genetic epidemiological perspective

Rates of atherosclerotic cardiovascular diseases (CVD) in the Western world have spectacularly decreased over the past 50 years. However, a substantial proportion of high-risk patients still develop heart attacks, strokes and valvular heart diseases despite benefiting from state-of-the-art treatments including lipid-lowering therapies. Over the past 10-15 years, it has become increasingly clear that Lipoprotein(a) (Lp[a]) is a critical component of this so-called residual risk. Genetic association studies revealed that Lp(a) is robustly, independently and causally associated with a broad range of cardiovascular and valvular heart diseases. Up to 1 billion people around the globe may have an Lp(a) level that places them in a high-risk category. Lp(a) is strongly associated with calcific aortic valve stenosis (CAVS), coronary artery disease (CAD), peripheral arterial disease (PAD) and to a lesser extent with ischemic stroke (IS) and heart failure (HF). Because of this strong association with cardiovascular and valvular heart diseases, Lp(a) even emerged as one of the most important genetic determinants of human lifespan and healthspan. Here, we review the evidence from the largest and most informative genetic association studies and prospective studies that have investigated the association between Lp(a) and human lifespan, healthspan, CVD, CAVS and non-cardiovascular diseases. We present Lp(a) threshold values that may be clinically relevant and identify other cardiovascular risk factors that may modulate the absolute risk of CVD in individuals with high Lp(a) levels. Finally, we identify key clinical and research questions that require further investigation to eventually and optimally reduce CVD risk in patients with high Lp(a) levels.

Lipoprotein(a) and its Significance in Cardiovascular Disease: A Review

Importance

Lipoprotein(a) (Lp[a]) is a low-density lipoprotein (LDL) cholesterol-like particle bound to apolipoprotein(a). This novel marker of cardiovascular disease acts through induction of vascular inflammation, atherogenesis, calcification, and thrombosis. While an absolute risk threshold remains to be universally accepted, an estimated 20% to 25% of the global population have Lp(a) levels of 50 mg/dL or higher, a level noted by the European Atherosclerosis Society to confer increased cardiovascular risk.

Observations

Compelling evidence from pathophysiological, observational, and genetic studies suggest a potentially causal association between high Lp(a) levels, atherosclerotic cardiovascular disease, and calcific aortic valve stenosis. Additional evidence has demonstrated that elevated Lp(a) levels are associated with a residual cardiovascular risk despite traditional risk factor optimization, including LDL cholesterol reduction. These findings have led to the formulation of the Lp(a) hypothesis, namely that Lp(a) lowering leads to cardiovascular risk reduction, intensifying the search for Lp(a)-reducing therapies. The ineffectiveness of lifestyle modification, statins, and ezetimibe to lower Lp(a); the modest Lp(a) reduction with proprotein convertase subtilisin/kexin type 9 inhibitors; the adverse effect profile and unclear cardiovascular benefit of pharmacotherapies such as niacin and mipomersen; and the impracticality of regular lipoprotein apheresis represent major challenges to currently available therapies. Nevertheless, emerging nucleic acid-based therapies, such as the antisense oligonucleotide pelacarsen and the small interfering RNA olpasiran, are generating interest because of their potent Lp(a)-lowering effects. Assessment of new-onset diabetes in patients achieving very low Lp(a) levels will be important in future trials.

Conclusions and Relevance

Epidemiologic and genetic studies suggest a potentially causal association between elevated Lp(a) levels, atherosclerotic cardiovascular disease, and aortic valve stenosis. Emerging nucleic acid-based therapies have potent Lp(a)-lowering effects and appear safe; phase 3 trials will establish whether they improve cardiovascular outcomes.

Role of oxidative stress in calcific aortic valve disease and its therapeutic implications

Calcific aortic valve disease (CAVD) is the end result of active cellular processes that lead to the progressive fibrosis and calcification of aortic valve leaflets. In western populations, CAVD is a significant cause of cardiovascular morbidity and mortality, and in the absence of effective drugs, it will likely represent an increasing disease burden as populations age. As there are currently no pharmacological therapies available for preventing, treating, or slowing the development of CAVD, understanding the mechanisms underlying the initiation and progression of the disease is important for identifying novel therapeutic targets. Recent evidence has emerged of an important causative role for reactive oxygen species (ROS)-mediated oxidative stress in the pathophysiology of CAVD, inducing the differentiation of valve interstitial cells into myofibroblasts and then osteoblasts. In this review, we focus on the roles and sources of ROS driving CAVD and consider their potential as novel therapeutic targets for this debilitating condition.

Association Between Lipoprotein(a) and Calcific Aortic Valve Disease: A Systematic Review and Meta-Analysis

Background

Preliminary studies indicated that enhanced plasma levels of lipoprotein(a) [lp(a)] might link with the risk of calcific aortic valve disease (CAVD), but the clinical association between them remained inconclusive. This systematic review and meta-analysis were aimed to determine this association.

Methods

We comprehensively searched PubMed, Embase, Web of Science, and Scopus databases for studies reporting the incidence of CAVD and their plasma lp(a) concentrations. Pooled risk ratio (RR) and 95% confidence interval (95% CI) were calculated to evaluate the effect of lp(a) on CAVD using the random-effects model. Subgroup analyses by study types, countries, and the level of adjustment were also conducted. Funnel plots, Egger's test and Begg's test were conducted to evaluate the publication bias.

Results

Eight eligible studies with 52,931 participants were included in this systematic review and meta-analysis. Of these, four were cohort studies and four were case-control studies. Five studies were rated as high quality, three as moderate quality. The pooled results showed that plasma lp(a) levels ≥50 mg/dL were associated with a 1.76-fold increased risk of CAVD (RR, 1.76; 95% CI, 1.47–2.11), but lp(a) levels ≥30 mg/dL were not observed to be significantly related with CAVD (RR, 1.28; 95% CI, 0.98–1.68). We performed subgroup analyses by study type, the RRs of cohort studies revealed lp(a) levels ≥50 mg/dL and lp(a) levels ≥30 mg/dL have positive association with CAVD (RR, 1.70; 95% CI, 1.39–2.07; RR 1.38; 95% CI, 1.19–1.61).

Conclusion

High plasma lp(a) levels (≥50 mg/dL) are significantly associated with increased risk of CAVD.

Lipoprotein(a) and Body Mass Compound the Risk of Calcific Aortic Valve Disease

BACKGROUND

High plasma lipoprotein(a) and high body mass index are both causal risk factors for calcific aortic valve disease.

OBJECTIVES

This study sought to test the hypothesis that risk of calcific aortic valve disease is the highest when both plasma lipoprotein(a) and body mass index are extremely high.

METHODS

From the Copenhagen General Population Study, we used information on 69,988 randomly selected individuals recruited from 2003 to 2015 (median follow-up 7.4 years) to evaluate the association between high lipoprotein(a) and high body mass index with risk of calcific aortic valve disease.

RESULTS

Compared with individuals in the 1st to 49th percentiles for both lipoprotein(a) and body mass index, the multivariable adjusted HRs for calcific aortic valve disease were 1.6 (95% CI: 1.3-1.9) for the 50th to 89th percentiles of both (16% of all individuals) and 3.5 (95% CI: 2.5-5.1) for the 90th to 100th percentiles of both (1.1%) (P for interaction = 0.92). The 10-year absolute risk of calcific aortic valve disease increased with higher lipoprotein(a), body mass index, and age, and was higher in men than in women. For women and men 70-79 years of age with body mass index ≥30.0 kg/m², 10-year absolute risks were 5% and 8% for lipoprotein(a) ≤42 mg/dL (88 nmol/L), 7% and 11% for 42-79 mg/dL (89-169 nmol/L), and 9% and 14% for lipoprotein(a) ≥80 mg/dL (170 nmol/L), respectively.

CONCLUSIONS

Extremely high lipoprotein(a) levels and extremely high body mass index together conferred a 3.5-fold risk of calcific aortic valve disease. Ten-year absolute risk of calcific aortic valve disease by categories of lipoprotein(a) levels, body mass index, age, and sex ranged from 0.4% to 14%.

Immune Response and Lipid Metabolism Gene Polymorphisms Are Associated with the Risk of Obesity in Middle-Aged and Elderly Patients

More than two billion people around the world are overweight or obese. Even in apparently healthy people, obesity has a potent effect on their quality of life. Experimental data indicate the role of infectious agents in systemic inflammation, revealing a correlation between the dietary habits of people with obesity and the level of systemic inflammation mediators, serum lipid concentration, and hormonal and immune status. This study aimed to determine the association of immune response and lipid metabolism gene polymorphisms with the risk of obesity. This study included 560 Caucasian participants living in Western Siberia (Russian Federation). A total of 52 polymorphic sites in 20 genes were analyzed using the 5′ TaqMan nuclease assay. Four risk-associated polymorphic variants were discovered—two variants in immune response genes (IL6R rs2229238, OR = 1.92, 95% CI = 1.36–2.7, p = 0.0002 in the dominant model; IL18 rs1946518, OR = 1.45, 95% CI = 1.03–2.04, p = 0.033 in the over-dominant model) and two variants in lipid metabolism genes (LPA rs10455872, OR = 1.86, 95% CI = 1.07–3.21, p = 0.026 in the log-additive model; LEPR rs1137100, OR = 2.88, 95% CI = 1.52–5.46, p = 0.001 in the recessive model). Thus, polymorphisms in immune response and lipid metabolism genes are potentially associated with the modification of obesity risk in the Caucasian population.

Lipoprotein(a) and aortic valve stenosis: A casual or causal association?

AIMS

This review aims to provide an update of available methods for imaging calcification activity and potential therapeutic options.

DATA SYNTHESIS

Aortic valve calcification represents the most common heart valve condition requiring treatment among adults in Western societies. No medical therapies are proven to be effective in treating symptoms or reducing disease progression. Therefore, surgical or transcatheter aortic valve replacement remains the only available treatment option. Elevated circulating concentrations of lipoprotein(a) is strongly associated with degenerative aortic stenosis. This relationship was first observed in prospective observational studies, and the causal relationship was confirmed in genetic studies.

CONCLUSIONS

New therapeutic targets have been identified and new imaging techniques could be used to test the effectiveness of new agents and further clarify the pathophysiology of AVS. No therapy that specifically lowers Lp (a) levels has been approved for clinical use.

Lipoprotein(a), a Lethal Player in Calcific Aortic Valve Disease

Calcified aortic valve disease (CAVD) is the most common valvular cardiovascular disease with increasing incidence and mortality. The primary treatment for CAVD is surgical or transcatheter aortic valve replacement and there remains a lack of effective drug treatment. Recently, lipoprotein (a) (Lp(a)) has been considered to play a crucial role in CAVD pathophysiology. Multiple studies have shown that Lp(a) represents an independent risk factor for CAVD. Moreover, Lp(a) mediates the occurrence and development of CAVD by affecting aortic valve endothelial dysfunction, indirectly promoting foam cell formation through oxidized phospholipids (OxPL), inflammation, oxidative stress, and directly promotes valve calcification. However, there is a lack of clinical trials with Lp(a) reduction as a primary endpoint. This review aims to explore the relationship and mechanism between Lp(a) and CAVD, and focuses on the current drugs that can be used as potential therapeutic targets for CAVD.

Impact of Fetuin-A, Lp(a), matrix gla protein and macrophage density on calcific aortic valve disease: a clinical study

BACKGROUND

Calcific aortic valve disease (CAVD) has a substantial and increasing burden in the ageing population with occult onset.Present study aimed to assess association of clinical characteristics of these patients and occurrence of CAVD.

METHODS

Patients diagnosed with CAVD and those receiving healthy medical examination in our hospital from January 2019 to February 2021 were enrolled in this retrospective study. Clinical characteristics, ultrasonic indicators, serological indicators and histology of CAVD were collected and compared among different groups. Logistic regression and Pearson correlation analysis was used to explore relationship between these indexes and occurrence of CAVD.

RESULTS

DBP, SBP, LVESD, LVEDD, IVS, PW, AV Vmax, TC, TG, LDL-C, Fetuin-A, Lp(a) in severe group were higher than mild, moderate and control groups (P<0.05), while those indexes of patients in moderate group were higher than that in mild and controlled groups (P<0.05). Besides, theses indexes of patients in mild group were also higher than that of controlled one (P<0.05). However, LVEF, HDL-C and MGP of patients in severe group was the lowest (P<0.05), while those in moderate group were lower than mild and controlled groups. Moreover, these indexes in mild group were also lower than control group (P<0.05). In Logistic regression analysis, MGP, Fetuin-A and Lp(a) were all independently associated with occurrence of CAVD (P<0.05). In Pearson correlation analysis, Fetuin-A and Lp(a) were positively correlated with progression of the disease, while MGP and macrophage density were negatively correlated with it.

CONCLUSIONS

Fetuin-A, MPG and Lp(a) were independently associated with the occurrence of CAVD, and they might be potential predictors for diagnosis of this disease.

Innate immune cells in the pathophysiology of calcific aortic valve disease: lessons to be learned from atherosclerotic cardiovascular disease?

Calcific aortic valve disease (CAVD) is the most common valvular disease in the developed world with currently no effective pharmacological treatment available. CAVD results from a complex, multifactorial process, in which valvular inflammation and fibro-calcific remodelling lead to valve thickening and cardiac outflow obstruction. The exact underlying pathophysiology of CAVD is still not fully understood, yet the development of CAVD shows many similarities with the pathophysiology of atherosclerotic cardiovascular disease (ASCVD), such as coronary artery disease. Innate immune cells play a crucial role in ASCVD and might also play a pivotal role in the development of CAVD. This review summarizes the current knowledge on the role of innate immune cells, both in the circulation and in the aortic valve, in the development of CAVD and the similarities and differences with ASCVD. Trained immunity and clonal haematopoiesis of indeterminate potential are proposed as novel immunological mechanisms that possibly contribute to the pathophysiology of CAVD and new possible treatment targets are discussed.

Lipoprotein(a): A Genetically Determined, Causal, and Prevalent Risk Factor for Atherosclerotic Cardiovascular Disease: A Scientific Statement From the American Heart Association

High levels of lipoprotein(a) [Lp(a)], an apoB100-containing lipoprotein, are an independent and causal risk factor for atherosclerotic cardiovascular diseases through mechanisms associated with increased atherogenesis, inflammation, and thrombosis. Lp(a) is predominantly a monogenic cardiovascular risk determinant, with ≈70% to ≥90% of interindividual heterogeneity in levels being genetically determined. The 2 major protein components of Lp(a) particles are apoB100 and apolipoprotein(a). Lp(a) remains a risk factor for cardiovascular disease development even in the setting of effective reduction of plasma low-density lipoprotein cholesterol and apoB100. Despite its demonstrated contribution to atherosclerotic cardiovascular disease burden, we presently lack standardization and harmonization of assays, universal guidelines for diagnosing and providing risk assessment, and targeted treatments to lower Lp(a). There is a clinical need to understand the genetic and biological basis for variation in Lp(a) levels and its relationship to disease in different ancestry groups. This scientific statement capitalizes on the expertise of a diverse basic science and clinical workgroup to highlight the history, biology, pathophysiology, and emerging clinical evidence in the Lp(a) field. Herein, we address key knowledge gaps and future directions required to mitigate the atherosclerotic cardiovascular disease risk attributable to elevated Lp(a) levels.

Lipoprotein(a) has no major impact on calcification activity in patients with mild to moderate aortic valve stenosis

OBJECTIVE

To assess whether patients with aortic valve stenosis (AS) with elevated lipoprotein(a) (Lp(a)) are characterised by increased valvular calcification activity compared with those with low Lp(a).

METHODS

We performed 18F-sodium fluoride (18F-NaF) positron emission tomography/CT in patients with mild to moderate AS (peak aortic jet velocity between 2 and 4 m/s) and high versus low Lp(a) (>50 mg/dL vs <50 mg/dL, respectively). Subjects were matched according to age, gender, peak aortic jet velocity and valve morphology. We used a target to background ratio with the most diseased segment approach to compare 18F-NaF uptake.

RESULTS

52 individuals (26 matched pairs) were included in the analysis. The mean age was 66.4±5.5 years, 44 (84.6%) were men, and the mean aortic valve velocity was 2.80±0.49 m/s. The median Lp(a) was 79 (64-117) mg/dL and 7 (5-11) mg/dL in the high and low Lp(a) groups, respectively. Systolic blood pressure and low-density-lipoprotein cholesterol (corrected for Lp(a)) were significantly higher in the low Lp(a) group (141±12 mm Hg vs 128±12 mm Hg, 2.5±1.1 mmol/L vs 1.9±0.8 mmol/L). We found no difference in valvular 18F-NaF uptake between the high and low Lp(a) groups (3.02±1.26 vs 3.05±0.96, p=0.902). Linear regression analysis showed valvular calcium score to be the only significant determinant of valvular 18F-NaF uptake (β=0.63; 95% CI 0.38 to 0.88 per 1000 Agatston unit increase, p<0.001). Lp(a) was not associated with 18F-NaF uptake (β=0.17; 95% CI -0.44 to 0.88, p=0.305 for the high Lp(a) group).

CONCLUSION

Among patients with mild to moderate AS, calcification activity is predominantly determined by established calcium burden. The results do not support our hypothesis that Lp(a) is associated with valvular 18F-NaF uptake.

Lipoprotein(a)—The Crossroads of Atherosclerosis, Atherothrombosis and Inflammation

Increased lipoprotein(a) (Lp(a)) levels are an independent predictor of coronary artery disease (CAD), degenerative aortic stenosis (DAS), and heart failure independent of CAD and DAS. Lp(a) levels are genetically determinated in an autosomal dominant mode, with great intra- and inter-ethnic diversity. Most variations in Lp(a) levels arise from genetic variations of the gene that encodes the apolipoprotein(a) component of Lp(a), the LPA gene. LPA is located on the long arm of chromosome 6, within region 6q2.6–2.7. Lp(a) levels increase cardiovascular risk through several unrelated mechanisms. Lp(a) quantitatively carries all of the atherogenic risk of low-density lipoprotein cholesterol, although it is even more prone to oxidation and penetration through endothelia to promote the production of foam cells. The thrombogenic properties of Lp(a) result from the homology between apolipoprotein(a) and plasminogen, which compete for the same binding sites on endothelial cells to inhibit fibrinolysis and promote intravascular thrombosis. LPA has up to 70% homology with the human plasminogen gene. Oxidized phospholipids promote differentiation of pro-inflammatory macrophages that secrete pro-inflammatory cytokines (e. g., interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-α). The aim of this review is to define which of these mechanisms of Lp(a) is predominant in different groups of patients.

Elevated lipoprotein(a) in mitral and aortic valve calcification and disease: The Copenhagen General Population Study

BACKGROUND AND AIMS

We tested the hypotheses (i) that elevated lipoprotein(a) is causally associated with both mitral and aortic valve calcification and disease, and (ii) that aortic valve calcification mediates the effect of elevated lipoprotein(a) on aortic valve stenosis.

METHODS

From the Copenhagen General Population study, we included 12,006 individuals who underwent cardiac computed tomography to measure mitral and aortic valve calcification and 85,884 to examine risk of heart valve disease. Participants had information on plasma lipoprotein(a) and genetic instruments associated with plasma lipoprotein(a) to investigate potential causality.

RESULTS

At age 70-79 years, 29% and 54% had mitral and aortic valve calcification, respectively. For 10-fold higher lipoprotein(a) levels, multifactorially adjusted odds ratios for mitral and aortic valve calcification were 1.26 (95% confidence interval: 1.13-1.41) and 1.62 (1.48-1.77). For mitral and aortic valve stenosis, corresponding hazard ratios were 0.93 (95%CI:0.40-2.15, 19 events) and 1.54 (1.38-1.71, 1158 events), respectively. For ≤23 versus ≥36 kringle IV type 2 number of repeats, the age and sex adjusted odds ratios for mitral and aortic valve calcification were 1.53 (1.18-1.99) and 2.23 (1.81-2.76). For carriers versus non-carriers of LPA rs10455872, odds ratios for mitral and aortic valve calcification were 1.33 (1.13-1.57) and 1.86 (1.64-2.13). For aortic valve stenosis, 31% (95%CI:16%-76%) of the effect of lipoprotein(a) was mediated through calcification.

CONCLUSIONS

Elevated lipoprotein(a) was genetically and observationally associated with mitral and aortic valve calcification and aortic valve stenosis. Aortic valve calcification mediated 31% of the effect of elevated lipoprotein(a) on aortic valve stenosis.

Calcific aortic valve disease: from molecular and cellular mechanisms to medical therapy

Calcific aortic valve disease (CAVD) is a highly prevalent condition that comprises a disease continuum, ranging from microscopic changes to profound fibro-calcific leaflet remodelling, culminating in aortic stenosis, heart failure, and ultimately premature death. Traditional risk factors, such as hypercholesterolaemia and (systolic) hypertension, are shared among atherosclerotic cardiovascular disease and CAVD, yet the molecular and cellular mechanisms differ markedly. Statin-induced low-density lipoprotein cholesterol lowering, a remedy highly effective for secondary prevention of atherosclerotic cardiovascular disease, consistently failed to impact CAVD progression or to improve patient outcomes. However, recently completed phase II trials provide hope that pharmaceutical tactics directed at other targets implicated in CAVD pathogenesis offer an avenue to alter the course of the disease non-invasively. Herein, we delineate key players of CAVD pathobiology, outline mechanisms that entail compromised endothelial barrier function, and promote lipid homing, immune-cell infiltration, and deranged phospho-calcium metabolism that collectively perpetuate a pro-inflammatory/pro-osteogenic milieu in which valvular interstitial cells increasingly adopt myofibro-/osteoblast-like properties, thereby fostering fibro-calcific leaflet remodelling and eventually resulting in left ventricular outflow obstruction. We provide a glimpse into the most promising targets on the horizon, including lipoprotein(a), mineral-binding matrix Gla protein, soluble guanylate cyclase, dipeptidyl peptidase-4 as well as candidates involved in regulating phospho-calcium metabolism and valvular angiotensin II synthesis and ultimately discuss their potential for a future therapy of this insidious disease.

Statin therapy and lipoprotein(a) levels: a systematic review and meta-analysis

AIMS 

Lipoprotein(a) [Lp(a)] is a causal and independent risk factor for cardiovascular disease (CVD). People with elevated Lp(a) are often prescribed statins as they also often show elevated low-density lipoprotein cholesterol (LDL-C) levels. While statins are well-established in lowering LDL-C, their effect on Lp(a) remains unclear. We evaluated the effect of statins compared to placebo on Lp(a) and the effects of different types and intensities of statin therapy on Lp(a).

METHODS AND RESULTS 

We conducted a systematic review and meta-analysis of randomized trials with a statin and placebo arm. Medline and EMBASE were searched until August 2019. Quality assessment of studies was done using Cochrane risk-of-bias tool (RoB 2). Mean difference of absolute and percentage changes of Lp(a) in the statin vs. the placebo arms were pooled using a random-effects meta-analysis. We compared effects of different types and intensities of statin therapy using subgroup- and network meta-analyses. Certainty of the evidence was determined using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation). Overall, 39 studies (24 448 participants) were included. Mean differences (95% confidence interval) of absolute and percentage changes in the statin vs. the placebo arms were 1.1 mg/dL (0.5-1.6, P < 0.0001) and 0.1% (-3.6% to 4.0%, P = 0.95), respectively (moderate-certainty evidence). None of the types of statins changed Lp(a) significantly compared to placebo (very low- to high-certainty evidence), as well as intensities of statin therapy (low- to moderate-certainty evidence).

CONCLUSION 

Statin therapy does not lead to clinically important differences in Lp(a) compared to placebo in patients at risk for CVD. Our findings suggest that in these patients, statin therapy will not change Lp(a)-associated CVD risk.

Lipoprotein(a) in hereditary hypercholesterolemia: Influence of the genetic cause, defective gene and type of mutation

BACKGROUND AND AIMS

Lipoprotein(a) [Lp(a)] concentration in heterozygous familial hypercholesterolemia (heFH) is not well established. Whether the genetic defect responsible for heFH plays a role in Lp(a) concentration is unknown. We aimed to compare Lp(a) in controls from a healthy population, in genetically diagnosed heFH and mutation-negative hypercholesterolemia subjects, and to assess the influence on Lp(a) of the genetic defect responsible for heFH.

METHODS

We conducted a cross-sectional study, performed in a lipid clinic in Spain. We studied adults with suspected heFH and a genetic study of FH genes (LDLR, APOB, APOE and PCSK9) and controls from de Aragon Workers' Health Study. HeFH patients from the Dyslipidemia Registry of the Spanish Atherosclerosis Society (SEA) were used as validation cohort.

RESULTS

Adjusted geometric means (95% confidence interval) of Lp(a) in controls (n = 1059), heFH (n = 500), and mutation-negative subjects (n = 860) were 14.9 mg/dL (13.6, 16.4), 21.9 mg/dL (18.1, 25.6) and 37.4 mg/dL (33.3, 42.1), p < 0.001 in all comparisons. Among heFH subjects, APOB-dependent FH showed the highest Lp(a), 36.5 mg/dL (22.0, 60.8), followed by LDLR-dependent FH, 21.7 mg/dL (17.9, 26.4). These differences were also observed in heFH from the SEA cohort. The number of plasminogen-like kringle IV type-2 repeats of LPA, the hypercholesterolemia polygenic score or LDLc concentration did not explain these differences. In LDLR-dependent FH, Lp(a) levels were not different depending on the affected protein domain.

CONCLUSIONS

Lp(a) is elevated in mutation-negative subjects and in heFH. The concentration of Lp(a) in heFH varies in relation to the responsible gene. Higher Lp(a) in heFH is not explained by their higher LDLc.

Lipoprotein Proteomics and Aortic Valve Transcriptomics Identify Biological Pathways Linking Lipoprotein(a) Levels to Aortic Stenosis

Lipoprotein(a) (Lp(a)) is one of the most important risk factors for the development of calcific aortic valve stenosis (CAVS). However, the mechanisms through which Lp(a) causes CAVS are currently unknown. Our objectives were to characterize the Lp(a) proteome and to identify proteins that may be differentially associated with Lp(a) in patients with versus without CAVS. Our second objective was to identify genes that may be differentially regulated by exposure to high versus low Lp(a) levels in explanted aortic valves from patients with CAVS. We isolated Lp(a) from the blood of 21 patients with CAVS and 22 volunteers and performed untargeted label-free analysis of the Lp(a) proteome. We also investigated the transcriptomic signature of calcified aortic valves from patients who underwent aortic valve replacement with high versus low Lp(a) levels (n = 118). Proteins involved in the protein activation cascade, platelet degranulation, leukocyte migration, and response to wounding may be associated with Lp(a) depending on CAVS status. The transcriptomic analysis identified genes involved in cardiac aging, chondrocyte development, and inflammation as potentially influenced by Lp(a). Our multi-omic analyses identified biological pathways through which Lp(a) may cause CAVS, as well as key molecular events that could be triggered by Lp(a) in CAVS development.

Lipoprotein (a): When to Measure and How to Treat?

PURPOSE OF REVIEW

The purpose of this article is to review current evidence for lipoprotein (a) (Lp(a)) as a risk factor for multiple cardiovascular (CV) disease phenotypes, provide a rationale for Lp(a) lowering to reduce CV risk, identify therapies that lower Lp(a) levels that are available clinically and under investigation, and discuss future directions.

RECENT FINDINGS

Mendelian randomization and epidemiological studies have shown that elevated Lp(a) is an independent and causal risk factor for atherosclerosis and major CV events. Lp(a) is also associated with non-atherosclerotic endpoints such as venous thromboembolism and calcific aortic valve disease. It contributes to residual CV risk in patients receiving standard-of-care LDL-lowering therapy. Plasma Lp(a) levels present a skewed distribution towards higher values and vary widely between individuals and according to ethnic background due to genetic variants in the LPA gene, but remain relatively constant throughout a person's life. Thus, elevated Lp(a) (≥50 mg/dL) is a prevalent condition affecting >20% of the population but is still underdiagnosed. Treatment guidelines have begun to advocate measurement of Lp(a) to identify patients with very high levels that have a family history of premature CVD or elevated Lp(a). Lipoprotein apheresis (LA) efficiently lowers Lp(a) and was recently associated with a reduction of incident CV events. Statins have neutral or detrimental effects on Lp(a), while PCSK9 inhibitors significantly reduce its level by up to 30%. Specific lowering of Lp(a) with antisense oligonucleotides (ASO) shows good safety and strong efficacy with up to 90% reductions. The ongoing CV outcomes study Lp(a)HORIZON will provide a first answer as to whether selective Lp(a) lowering with ASO reduces the risk of major CV events. Given the recently established association between Lp(a) level and CV risk, guidelines now recommend Lp(a) measurement in specific clinical conditions. Accordingly, Lp(a) is a current target for drug development to reduce CV risk in patients with elevated levels, and lowering Lp(a) with ASO represents a promising avenue.

Lipoprotein(a) and Cardiovascular Disease

BACKGROUND

High lipoprotein(a) concentrations present in 10%-20% of the population have long been linked to increased risk of ischemic cardiovascular disease. It is unclear whether high concentrations represent an unmet medical need. Lipoprotein(a) is currently not a target for treatment to prevent cardiovascular disease.

CONTENT

The present review summarizes evidence of causality for high lipoprotein(a) concentrations gained from large genetic epidemiologic studies and discusses measurements of lipoprotein(a) and future treatment options for high values found in an estimated >1 billion individuals worldwide.

SUMMARY

Evidence from mechanistic, observational, and genetic studies support a causal role of lipoprotein(a) in the development of cardiovascular disease, including coronary heart disease and peripheral arterial disease, as well as aortic valve stenosis, and likely also ischemic stroke. Effect sizes are most pronounced for myocardial infarction, peripheral arterial disease, and aortic valve stenosis where high lipoprotein(a) concentrations predict 2- to 3-fold increases in risk. Lipoprotein(a) measurements should be performed using well-validated assays with traceability to a recognized calibrator to ensure common cut-offs for high concentrations and risk assessment. Randomized cardiovascular outcome trials are needed to provide final evidence of causality and to assess the potential clinical benefit of novel, potent lipoprotein(a) lowering therapies.

Lipoprotein(a)

Lipoprotein(a) [Lp(a)] is an atherogenic lipoprotein with a strong genetic regulation. Up to 90% of the concentrations are explained by a single gene, the LPA gene. The concentrations show a several-hundred-fold interindividual variability ranging from less than 0.1 mg/dL to more than 300 mg/dL. Lp(a) plasma concentrations above 30 mg/dL and even more above 50 mg/dL are associated with an increased risk for cardiovascular disease including myocardial infarction, stroke, aortic valve stenosis, heart failure, peripheral arterial disease, and all-cause mortality. Since concentrations above 50 mg/dL are observed in roughly 20% of the Caucasian population and in an even higher frequency in African-American and Asian-Indian ethnicities, it can be assumed that Lp(a) is one of the most important genetically determined risk factors for cardiovascular disease.Carriers of genetic variants that are associated with high Lp(a) concentrations have a markedly increased risk for cardiovascular events. Studies that used these genetic variants as a genetic instrument to support a causal role for Lp(a) as a cardiovascular risk factor are called Mendelian randomization studies. The principle of this type of studies has been introduced and tested for the first time ever with Lp(a) and its genetic determinants.There are currently no approved pharmacologic therapies that specifically target Lp(a) concentrations. However, some therapies that target primarily LDL cholesterol have also an influence on Lp(a) concentrations. These are mainly PCSK9 inhibitors that lower LDL cholesterol by 60% and Lp(a) by 25-30%. Furthermore, lipoprotein apheresis lowers both, Lp(a) and LDL cholesterol, by about 60-70%. Some sophisticated study designs and statistical analyses provided support that lowering Lp(a) by these therapies also lowers cardiovascular events on top of the effect caused by lowering LDL cholesterol, although this was not the main target of the therapy. Currently, new therapies targeting RNA such as antisense oligonucleotides (ASO) or small interfering RNA (siRNA) against apolipoprotein(a), the main protein of the Lp(a) particle, are under examination and lower Lp(a) concentrations up to 90%. Since these therapies specifically lower Lp(a) concentrations without influencing other lipoproteins, they will serve the last piece of the puzzle whether a decrease of Lp(a) results also in a decrease of cardiovascular events.

The Riskier Lipid: What Is on the HORIZON for Lipoprotein (a) and Should There Be Lp(a) Screening for All?

PURPOSE OF REVIEW

Despite widespread targeting of cardiovascular risk factors, many patients continue to experience clinical events. This residual risk has stimulated efforts to develop novel therapeutic approaches to target additional factors underscoring cardiovascular disease. This review aimed to summarize existing evidence supporting targeting of Lp(a) as a novel cardioprotective strategy.

RECENT FINDINGS

Increasing evidence has implicated lipoprotein (a) [Lp(a)] in the pathogenesis of both atherosclerotic and calcific aortic valve disease. Therapeutic advances have produced novel agents that selectively lower Lp(a) levels, which have now progressed to evaluate their impact on cardiovascular events in large clinical outcome trials. Evidence continues to accumulate suggesting that targeting Lp(a) may be effective in reducing cardiovascular risk. With advances in Lp(a) targeted therapeutics, clinical trials now have the opportunity to determine whether this strategy will be effective for high-risk patients.

Diabetes Mellitus and Its Implications in Aortic Stenosis Patients

Aortic stenosis (AS) and diabetes mellitus (DM) are both progressive diseases that if left untreated, result in significant morbidity and mortality. Several studies revealed that the prevalence of DM is substantially higher in patients with AS and, thus, the progression from mild to severe AS is greater in those patients with DM. DM and common comorbidities associated with both diseases, DM and AS, increase patient management complexity and make aortic valve replacement the only effective treatment. For that reason, a better understanding of the pathogenesis underlying both these diseases and the relationships between them is necessary to design more appropriate preventive and therapeutic approaches. In this review, we provided an overview of the main aspects of the relationship between AS and DM, including common comorbidities and risk factors. We also discuss the established treatments/therapies in patients with AS and DM.

Lipoprotein(a) is robustly associated with aortic valve calcium

Objectives

To investigate the prevalence and quantity of aortic valve calcium (AVC) in two large cohorts, stratified according to age and lipoprotein(a) (Lp(a)), and to assess the association between Lp(a) and AVC.

Methods

We included 2412 participants from the population-based Rotterdam Study (52% women, mean age=69.6±6.3 years) and 859 apparently healthy individuals from the Amsterdam University Medical Centers (UMC) outpatient clinic (57% women, mean age=45.9±11.6 years). All individuals underwent blood sampling to determine Lp(a) concentration and non-enhanced cardiac CT to assess AVC. Logistic and linear regression analyses were performed to investigate the associations of Lp(a) with the presence and amount of AVC.

Results

The prevalence of AVC was 33.1% in the Rotterdam Study and 5.4% in the Amsterdam UMC cohort. Higher Lp(a) concentrations were independently associated with presence of AVC in both cohorts (OR per 50 mg/dL increase in Lp(a): 1.54 (95% CI 1.36 to 1.75) in the Rotterdam Study cohort and 2.02 (95% CI 1.19 to 3.44) in the Amsterdam UMC cohort). In the Rotterdam Study cohort, higher Lp(a) concentrations were also associated with increase in aortic valve Agatston score (β 0.19, 95% CI 0.06 to 0.32 per 50 mg/dL increase).

Conclusions

Lp(a) is robustly associated with presence of AVC in a wide age range of individuals. These results provide further rationale to assess the effect of Lp(a) lowering interventions in individuals with early AVC to prevent end-stage aortic valve stenosis.

Role of inflammation, autotaxin and lipoprotein (a) in degenerative aortic valve stenosis in patients with coronary artery disease

Aim. To study the relationship between the concentration of lipoprotein (a) (Lp (a)) and autotaxin (ATX) in patients with and without degenerative aortic valve stenosis (AoS) in the presence of coronary artery disease (CAD).

Material and methods. The study included 461 patients (mean age, 66±11 years, men, 323), 354 of whom had CAD with stenosis ≥50% in at least one coronary artery according to angiography. Degenerative AoS was diagnosed with ultrasound. The control group consisted of 107 patients without CAD and degenerative AoS. Concentrations of Lp (a), ATX, lipids and blood cells were measured for all patients.

Results. CAD without degenerative AoS (group 1) was diagnosed in 307 patients, while 47 patients had CAD and degenerative AoS (group 2). Patients in both groups were older than patients in the control group (66±10, 74±8, and 61±13 years, respectively). The ATX level was lower in group 1 (median [25; 75%]: 495 [406; 583] ng/ml) than in the control group (545 [412; 654] ng/ml) or group 2 (545 [476; 605] ng/ml) (p<0,05 for all). Lp (a) was lower in the control group (14,5 [5,5; 36,0] mg/dl) than in group 1 (24,9 [9,7; 58,4] mg/dl) (p<0,005) and group 2 (23,8 [9,9; 75,7] mg/dL) (p<0,05). According to the logistic regression, an increased ATX level, regardless of age and other risk factors, was associated with degenerative AoS only in patients with CAD, while age and neutrophil to lymphocyte ratio were associated with the development of degenerative AoS both in patients with CAD and the general group.

Conclusion. An elevated Lp (a) level is associated with CAD regardless of the aortic valve involvement, while an increased concentration of ATX and neutrophil to lymphocyte ratio in patients with CAD were associated with degenerative AoS regardless of age and other risk factors.

Treatment and prevention of lipoprotein(a)-mediated cardiovascular disease: the emerging potential of RNA interference therapeutics

Lipid- and lipoprotein-modifying therapies have expanded substantially in the last 25 years, resulting in reduction in the incidence of major adverse cardiovascular events. However, no specific lipoprotein(a) [Lp(a)]-targeting therapy has yet been shown to reduce cardiovascular disease risk. Many epidemiological and genetic studies have demonstrated that Lp(a) is an important genetically determined causal risk factor for coronary heart disease, aortic valve disease, stroke, heart failure, and peripheral vascular disease. Accordingly, the need for specific Lp(a)-lowering therapy has become a major public health priority. Approximately 20% of the global population (1.4 billion people) have elevated levels of Lp(a) associated with higher cardiovascular risk, though the threshold for determining ‘high risk’ is debated. Traditional lifestyle approaches to cardiovascular risk reduction are ineffective at lowering Lp(a). To address a lifelong risk factor unmodifiable by non-pharmacological means, Lp(a)-lowering therapy needs to be safe, highly effective, and tolerable for a patient population who will likely require several decades of treatment. N-acetylgalactosamine-conjugated gene silencing therapeutics, such as small interfering RNA (siRNA) and antisense oligonucleotide targeting LPA, are ideally suited for this application, offering a highly tissue- and target transcript-specific approach with the potential for safe and durable Lp(a) lowering with as few as three or four doses per year. In this review, we evaluate the causal role of Lp(a) across the cardiovascular disease spectrum, examine the role of established lipid-modifying therapies in lowering Lp(a), and focus on the anticipated role for siRNA therapeutics in treating and preventing Lp(a)-related disease.

Menaquinone 4 increases plasma lipid levels in hypercholesterolemic mice

In calcific aortic valve disease (CAVD) progressive valvular calcification causes aortic valve dysfunction. CAVD has several risk factors such as age and dyslipidemia. Vitamin K was shown to inhibit vascular calcification in mice and valvular calcification in patients with CAVD. We studied the effect of menaquinone 4 (MK4/vitamin K2) on valvular calcification in the hypercholesterolemic mouse model of CAVD. LDLr^−/−ApoB^100/100 male mice were fed with a Western diet for 5 months, with (n = 10) or without (n = 10) added 0.2 mg/g MK4. Body weight gain was followed weekly. Morphology of aortic valves and liver was assessed with immunohistochemistry. Plasma cholesterol levels and cytokines from hepatic tissue were assessed in the end of the study. Hepatic gene expression of lipid metabolism regulating genes were assessed after 18 h diet. MK4 exacerbated the lipoprotein lipid profile without affecting aortic valve morphology in hypercholesterolemic LDLr^−/− ApoB^100/100 mice. The MK4-containing WD diet increased plasma levels of LDL and triglycerides, hepatic steatosis, and mRNA expression of genes required for triglyceride and cholesterol synthesis. MK4 diminished levels of several cytokines and chemokines in liver, including IL-6, TNFα and MCP1, as measured by hepatic cytokine array. Consequently, MK4 may exert non-beneficial effects on circulating lipid levels, especially in hypercholesterolemic individuals.

An Exploratory Analysis of Proprotein Convertase Subtilisin/Kexin Type 9 Inhibition and Aortic Stenosis in the FOURIER Trial

Importance

Despite recent advances in treatment of severe aortic valve stenosis (AS), AS remains a life-threatening condition with no proven disease-modifying therapy. Low-density lipoprotein cholesterol (LDL-C) and lipoprotein(a) (Lp[a]) have been implicated in the pathobiology of AS. The proprotein convertase subtilisin/kexin type 9 inhibitor evolocumab reduces circulating LDL-C concentrations by 50% to 60% and Lp(a) by 20% to 30%.

Objective

To determine whether evolocumab reduces the risk of AS events in patients with atherosclerotic cardiovascular disease.

Interventions

Patients were randomized 1:1 to evolocumab or placebo.

Design, Setting, and Participants

Exploratory analysis of the FOURIER trial, which enrolled 27 564 patients with stable atherosclerotic cardiovascular disease who were taking statin therapy at 1242 sites in 49 countries from February 2013 to November 2016. Patients were randomized to evolocumab or placebo and followed up for a median (interquartile range) of 2.2 (1.8-2.5) years. This post hoc analysis was performed from September 2019 to February 2020.

Main Outcomes and Measures

Site-reported adverse events of new or worsening AS or aortic valve replacement (termed AS events). The adjusted risk of AS events was calculated with a multivariable model including concentrations of Lp(a) and LDL-C corrected for Lp(a) content, plus age, sex, diabetes, hypertension, current smoking, and estimated glomerular filtration rate. Evolocumab efficacy was tested using a Cox proportional hazards model.

Results

Aortic stenosis events occurred in 63 patients (48 men [76%]; mean [SD] age, 69 [9] years) over a median of 2.2 years. Elevated Lp(a) concentration was associated with higher rates of AS events (adjusted hazard ratio [aHR], 1.55 [95% CI, 1.17-2.05] per SD; P = .002), including aortic valve replacement (aHR, 2.22 [95% CI, 1.38-3.58] per SD; P = .001), after multivariable adjustment. The corrected LDL-C concentration was not significantly associated with AS events (aHR, 1.23 [95% CI, 0.93-1.61] per SD; P = .14). The overall HR for AS events with evolocumab was 0.66 (95% CI, 0.40-1.09), with no apparent association in the first year (HR, 1.09 [95% CI, 0.48-2.47]) but an HR of 0.48 (95% CI, 0.25-0.93) after the first year of treatment.

Conclusions and Relevance

In this exploratory analysis of the FOURIER trial, higher Lp(a) levels, but not Lp(a)-corrected LDL-C levels, were associated with a higher risk of subsequent AS events, including aortic valve replacement. Long-term therapy with evolocumab may reduce AS events, and this raises the possibility that specific pharmacologic lipid-lowering therapy could offer a means to prevent or slow the progression of AS. These exploratory findings merit further investigation with a dedicated randomized clinical trial.

Trial Registration

ClinicalTrials.gov Identifier: NCT01764633.

Metabolomic Signature of Human Aortic Valve Stenosis

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This study is the first step towards the creation of a metabolomic map of calcified human aortic valves.

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The study highlights an independent association of LysoPA with CAVS severity.

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The study demonstrates that LysoPA levels are associated with faster CAVS progression rate.

This study outlines the first step toward creating the metabolite atlas of human calcified aortic valves by identifying the expression of metabolites and metabolic pathways involved at various stages of calcific aortic valve stenosis progression. Untargeted analysis identified 72 metabolites and lipids that were significantly altered (p < 0.01) across different stages of disease progression. Of these metabolites and lipids, the levels of lysophosphatidic acid were shown to correlate with faster hemodynamic progression and could select patients at risk for faster progression rate.

High lipoprotein(a) and high risk of mortality

AIMS

Several lipoprotein(a)-lowering therapies are currently being developed with the long-term goal of reducing cardiovascular disease and mortality; however, the relationship between lipoprotein(a) and mortality is unclear. We tested the hypothesis that lipoprotein(a) levels are associated with risk of mortality.

METHODS AND RESULTS

We studied individuals from two prospective studies of the Danish general population, of which 69 764 had information on lipoprotein(a) concentrations, 98 810 on LPA kringle-IV type 2 (KIV-2) number of repeats, and 119 094 on LPA rs10455872 genotype. Observationally, lipoprotein(a) >93 mg/dL (199 nmol/L; 96th-100th percentiles) vs. <10 mg/dL (18 nmol/L; 1st-50th percentiles) were associated with a hazard ratio of 1.50 (95% confidence interval 1.28-1.76) for cardiovascular mortality and of 1.20 (1.10-1.30) for all-cause mortality. The median survival for individuals with lipoprotein(a) >93 mg/dL (199 nmol/L; 96th-100th percentiles) and ≤93 mg/dL (199 nmol/L; 1st-95th percentiles) were 83.9 and 85.1 years (log rank P = 0.005). For cardiovascular mortality, a 50 mg/dL (105 nmol/L) increase in lipoprotein(a) levels was associated observationally with a hazard ratio of 1.16 (1.09-1.23), and genetically with risk ratios of 1.23 (1.08-1.41) based on LPA KIV2 and of 0.98 (0.88-1.09) based on LPA rs10455872. For all-cause mortality, corresponding values were 1.05 (1.01-1.09), 1.10 (1.04-1.18), and 0.97 (0.92-1.02), respectively. Finally, for a similar cholesterol content increase, lipoprotein(a) was more strongly associated with cardiovascular and all-cause mortality than low-density lipoprotein, implying that the mortality effect of high lipoprotein(a) is above that explained by its cholesterol content.

CONCLUSION

High levels of lipoprotein(a), through corresponding low LPA KIV-2 number of repeats rather than through high cholesterol content were associated with high risk of mortality. These findings are novel.

Correlation Between Plasma Matrix Metalloproteinase-28 Levels and Severity of Calcific Aortic Valve Stenosis

BACKGROUND Calcific aortic valve disease is a common cardiovascular disorder worldwide. This study aimed to investigate the correlation between plasma matrix metalloproteinase-28 (MMP-28) levels and the severity of calcific aortic valve stenosis. MATERIAL AND METHODS Calcific aortic valve stenosis patients who were admitted to the heart center of our hospital between January 2016 and January 2019 to undergo surgery were successively enrolled in this study (55 males and 24 females with an average age of 58.5±9.6). Information on echocardiography, plasma MMP-28 levels, and other clinical data of the patients was retrospectively collected. RESULTS The average plasma MMP-28 level was 2.43±2.22 ng/mL (range, 0.22-8.27 ng/mL). Plasma MMP-28 levels in patients with mild (n=24), moderate (n=31), or severe (n=24) aortic valve stenosis were 0.74 (0.25-2.23), 1.46 (0.50-3.22), and 4.13 (1.54-6.18) ng/mL, respectively, indicating that the patients with severe aortic valve stenosis had significantly higher MMP-28 levels than the patients with moderate or mild aortic valve stenosis (both P<0.01). Regression analysis using the general linear model further revealed that plasma MMP-28 level was correlated with the peak blood flow velocity and mean pressure gradient of the transaortic valve, and the correlations were statistically significant (both P<0.01). CONCLUSIONS MMP-28 level is significantly elevated in severe cases of calcific aortic valve stenosis. Moreover, plasma MMP-28 levels are positively correlated with the mean pressure gradients and peak blood flow velocity of the transaortic valve.

Risks of Incident Cardiovascular Disease Associated With Concomitant Elevations in Lipoprotein(a) and Low-Density Lipoprotein Cholesterol-The Framingham Heart Study

Background Elevated lipoprotein(a) is a well-established risk factor for atherosclerotic vascular disease but is not measured in routine clinical care. Screening of high lipoprotein(a) in individuals with moderate elevations of low-density lipoprotein cholesterol (LDL-C) may identify individuals at high risk of cardiovascular disease. Methods and Results We examined 2606 Framingham Offspring participants (median age, 54 years; 45% men) prospectively with a median follow-up of 15 years (n=392 incident cardiovascular events). Individuals with higher (≥100 nmol/L) versus lower lipoprotein(a) were divided into groups based on LDL-C <135 mg/dL versus ≥135 mg/dL. In Cox models, after adjustment for known risk factors, high lipoprotein(a) (≥100 nmol/L) and LDL-C ≥135 mg/dL were each significant predictors of cardiovascular disease (LDL-C ≥135 mg/dL: hazard ratio [HR], 1.34; 95% CI, 1.09-1.64; P=0.006; high lipoprotein (a): HR, 1.31; 95% CI, 1.03-1.66; P=0.026). Across the groups of high/low lipoprotein (a) and LDL-C ≥135 mg/dL or <135 mg/dL, the absolute cardiovascular disease risks at 15 years were 22.6% (high lipoprotein(a)/LDL-C ≥135 mg/dL, n=248), 17.3% (low lipoprotein(a)/LDL-C ≥135 mg/dL, n=758), 12.7% (high lipoprotein(a)/LDL-C <135 mg/dL, n=275) and 11.5% (low lipoprotein(a)/LDL-C <135 mg/dL, n=1328, reference group). Among individuals with LDL-C ≥135 mg/dL, those with high lipoprotein(a) had a 43% higher risk (HR, 1.43; 95% CI, 1.05-1.97; P=0.02). Presence of high lipoprotein(a) with moderate LDL-C levels (135-159 mg/dL) yielded absolute risks equivalent to those with LDL-C ≥160 mg/dL (23.5%, 95% CI, 17.4%-31.3%; and 20.7%, 95% CI, 16.8%-25.3%, respectively). Conclusions Concomitant elevation of LDL-C ≥135 mg/dL and lipoprotein(a) ≥100 nmol/L is associated with a high absolute risk of incident cardiovascular disease. lipoprotein(a) measurement in individuals with moderate elevations in LDL-C, who do not otherwise meet criteria for statins, may identify individuals at high cardiovascular risk.

Plasma lipoprotein(a) concentration as an independent predictor of hemodynamic progression of aortic valve stenosis

Calcific aortic valve disease (CAVD) is a common cardiovascular disorder of high social significance. This study aimed to identify independent predictors of hemodynamic progression of CAVD. The relationship between some risk factors, including the rs10455872 polymorphism in the intron 25 of the lipoprotein(a) [Lp(a)] coding region and the plasma Lp(a) concentration, and CAVD severity were prospectively examined in 114 patients. Age (p = 0.023), smoking (p = 0.038), lack of obesity (p = 0.005), triglyceride levels (p = 0.039), and plasma Lp(a) (p < 0.0001) levels were found to be significant determinants of stenosis progression. The rs10455872 polymorphism; however, was not found to be a significant factor for neither the stenosis severity (p = 0.773) nor for plasma Lp(a) levels (p = 0.617). We established a highly significant Lp(a) cut-off concentration (21.2 mg/dL) distinguishing the aortic valve calcification without stenosis from the significant stenosis. Plasma Lp(a) concentration was the only independent predictor of disease progression (p < 0.0001). Moreover, patients with plasma levels of Lp(a) ≥ 21.2 mg/dL were 55 times more likely to develop aortic valve stenosis. We conclude that Lp(a) concentration may prove valuable for more reliable identification of patients at risk of accelerated CAVD development. Future studies are desirable to determine whether plasma Lp(a) levels could be used as a potential biomarker for aortic stenosis progression.

Interaction of Autotaxin With Lipoprotein(a) in Patients With Calcific Aortic Valve Stenosis

Our objectives were to determine whether autotaxin (ATX) is transported by lipoprotein(a) [Lp(a)] in human plasma and if could be used as a biomarker of calcific aortic valve stenosis (CAVS). We first found that ATX activity was higher in Lp(a) compared to low-density lipoprotein fractions in isolated fractions of 10 healthy participants. We developed a specific assay to measure ATX-Lp(a) in 88 patients with CAVS and 144 controls without CAVS. In a multivariable model corrected for CAVS risk factors, ATX-Lp(a) was associated with CAVS (p = 0.003). We concluded that ATX is preferentially transported by Lp(a) and might represent a novel biomarker for CAVS.

Diet and Lp(a): Does Dietary Change Modify Residual Cardiovascular Risk Conferred by Lp(a)?

Lipoprotein(a) [Lp(a)] is an independent, causal, genetically determined risk factor for cardiovascular disease (CVD). We provide an overview of current knowledge on Lp(a) and CVD risk, and the effect of pharmacological agents on Lp(a). Since evidence is accumulating that diet modulates Lp(a), the focus of this paper is on the effect of dietary intervention on Lp(a). We identified seven trials with 15 comparisons of the effect of saturated fat (SFA) replacement on Lp(a). While replacement of SFA with carbohydrate, monounsaturated fat (MUFA), or polyunsaturated fat (PUFA) consistently lowered low-density lipoprotein cholesterol (LDL-C), heterogeneity in the Lp(a) response was observed. In two trials, Lp(a) increased with carbohydrate replacement; one trial showed no effect and another showed Lp(a) lowering. MUFA replacement increased Lp(a) in three trials; three trials showed no effect and one showed lowering. PUFA or PUFA + MUFA inconsistently affected Lp(a) in four trials. Seven trials of diets with differing macronutrient compositions showed similar divergence in the effect on LDL-C and Lp(a). The identified clinical trials show diet modestly affects Lp(a) and often in the opposing direction to LDL-C. Further research is needed to understand how diet affects Lp(a) and its properties, and the lack of concordance between diet-induced LDL-C and Lp(a) changes.

Lipoprotein-associated phospholipase A2 activity, genetics and calcific aortic valve stenosis in humans

BACKGROUND

Lipoprotein-associated phospholipase A2 (Lp-PLA2) activity has been shown to predict calcific aortic valve stenosis (CAVS) outcomes. Our objective was to test the association between plasma Lp-PLA2 activity and genetically elevated Lp-PLA2 mass/activity with CAVS in humans.

METHODS AND RESULTS

Lp-PLA2 activity was measured in 890 patients undergoing cardiac surgery, including 476 patients undergoing aortic valve replacement for CAVS and 414 control patients undergoing coronary artery bypass grafting. After multivariable adjustment, Lp-PLA2 activity was positively associated with the presence of CAVS (OR=1.21 (95% CI 1.04 to 1.41) per SD increment). We selected four single nucleotide polymorphisms (SNPs) at the PLA2G7 locus associated with either Lp-PLA2 mass or activity (rs7756935, rs1421368, rs1805017 and rs4498351). Genetic association studies were performed in eight cohorts: Quebec-CAVS (1009 cases/1017 controls), UK Biobank (1350 cases/349 043 controls), European Prospective Investigation into Cancer and Nutrition-Norfolk (504 cases/20 307 controls), Genetic Epidemiology Research on Aging (3469 cases/51 723 controls), Malmö Diet and Cancer Study (682 cases/5963 controls) and three French cohorts (3123 cases/6532 controls), totalling 10 137 CAVS cases and 434 585 controls. A fixed-effect meta-analysis using the inverse-variance weighted method revealed that none of the four SNPs was associated with CAVS (OR=0.99 (95% CI 0.96 to 1.02, p=0.55) for rs7756935, 0.97 (95% CI 0.93 to 1.01, p=0.11) for rs1421368, 1.00 (95% CI 1.00 to 1.01, p=0.29) for rs1805017, and 1.00 (95% CI 0.97 to 1.04, p=0.87) for rs4498351).

CONCLUSIONS

Higher Lp-PLA2 activity is significantly associated with the presence of CAVS and might represent a biomarker of CAVS in patients with heart disease. Results of our genetic association study suggest that Lp-PLA2 is however unlikely to represent a causal risk factor or therapeutic target for CAVS.

Genetic and In Vitro Inhibition of PCSK9 and Calcific Aortic Valve Stenosis

The authors investigated whether PCSK9 inhibition could represent a therapeutic strategy in calcific aortic valve stenosis (CAVS). A meta-analysis of 10 studies was performed to determine the impact of the PCSK9 R46L variant on CAVS, and the authors found that CAVS was less prevalent in carriers of this variant (odds ratio: 0.80 [95% confidence interval: 0.70 to 0.91]; p = 0.0011) compared with noncarriers. PCSK9 expression was higher in the aortic valves of patients CAVS compared with control patients. In human valve interstitials cells submitted to a pro-osteogenic medium, PCSK9 levels increased and a PCSK9 neutralizing antibody significantly reduced calcium accumulation.

Lipoprotein (a): An Update on a Marker of Residual Risk and Associated Clinical Manifestations

Lipoprotein (a) [Lp(a)] is a low-density, cholesterol-containing lipoprotein that differs from other low-density lipoproteins due to the presence of apolipoprotein(a) bound to its surface apolipoprotein B100. Multiple epidemiologic studies, including Mendelian Randomization studies, have demonstrated that increasing Lp(a) levels are associated with increased risk of heart disease, including atherosclerotic cardiovascular disease and calcific aortic stenosis. The risk associated with elevations in Lp(a) appears to be independent of other lipid markers. While the current treatment options for elevated Lp(a) are limited, promising new therapies are under development, leading to renewed interest in Lp(a). This review provides an overview of the biology and epidemiology of Lp(a), available outcome studies, and insights into future therapies.

Lipoprotein(a) and calcific aortic valve stenosis: A systematic review

Calcific aortic valve stenosis (AS) is the most common form of acquired valvular heart disease needing intervention and our understanding of this disease has evolved from one of degenerative calcification to that of an active process driven by the interplay of genetic factors and chronic inflammation modulated by risk factors such as smoking, hypertension and elevated cholesterol. Lipoprotein(a) [Lp (a)] is a cholesterol rich particle secreted by the liver which functions as the major lipoprotein carrier of phosphocholine-containing oxidized phospholipids. Lp(a) levels are largely genetically determined by polymorphisms in the LPA gene. While there is an extensive body of evidence linking Lp(a) to atherosclerotic cardiovascular disease, emerging evidence now suggests a similar association of Lp(a) to calcific AS. In this article, we performed a systematic review of all published literature to assess the association between Lp(a) and calcific aortic valve (AV) disease. In addition, we review the potential mechanisms by which Lp(a) influences the progression of valve disease. Our review identified a total of 21 studies, varying from case-control studies, prospective or retrospective observational cohort studies to Mendelian randomized studies that assessed the association between Lp(a) and calcific AS. All but one of the above studies demonstrated significant association between elevated Lp(a) and calcific AS. We conclude that there is convincing evidence supporting a causal association between elevated Lp(a) and calcific AS. In addition, elevated Lp(a) predicts a faster hemodynamic progression of AS, and increased risk of AV replacement, especially in younger patients. Further research into the clinical utility of Lp(a) as a marker for predicting the incidence, progression, and outcomes of sclerodegenerative AV disease is needed.

Lipoprotein(a): Expanding our knowledge of aortic valve narrowing

Elevated levels of lipoprotein(a) [Lp(a)] have been identified as an independent and causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and, more recently, calcific aortic valve disease (CAVD). CAVD is a slow, progressive disorder presenting as severe trileaflet calcification known as aortic valve stenosis (AS) that impairs valve motion and restricts ventricular outflow. AS afflicts 2% of the aging population (≥ 65 years) and tends to be quite advanced by the time it presents clinical symptoms of exertional angina, syncope, or heart failure. Currently, the only effective clinical therapy for AS patients is surgical or transcatheter aortic valve replacement. Evidence is accumulating that Lp(a) can exacerbate pathophysiological processes in CAVD, specifically, endothelial dysfunction, formation of foam cells, and promotion of a pro-inflammatory state. In the valve milieu, the pro-inflammatory effects of Lp(a) are manifested in valve thickening and mineralization through pro-osteogenic signaling and changes in gene expression in valve interstitial cells that is primarily facilitated by the oxidized phospholipid content of Lp(a). In AS pathogenesis, an incomplete understanding of the role of Lp(a) at the molecular level and the absence of appropriate animal models are barriers for the development of specific and effective clinical interventions designed to mitigate the role of Lp(a) in AS. However, the advent of effective therapies that dramatically lower Lp(a) provides the possibility of the first medical treatment to halt AS progression.

Lipoprotein(a) and Cardiovascular Diseases - Revisited

Two decades ago, it was recognized that lipoprotein(a) (Lp(a)) concentrations were elevated in patients with cardiovascular disease (CVD). However, the importance of Lp(a) was not strongly established due to a lack of both Lp(a)-lowering therapy and evidence that reducing Lp(a) levels improves CVD risk. Recent advances in clinical and genetic research have revealed the crucial role of Lp(a) in the pathogenesis of CVD. Mendelian randomization studies have shown that Lp(a) concentrations are causal for different CVDs, including coronary artery disease, calcified aortic valve disease, stroke, and heart failure, despite optimal low-density lipoprotein cholesterol (LDL-C) management. Lp(a) consists of apolipoprotein (apo) B100 covalently bound to apoA. Thus, Lp(a) has atherothrombotic traits of both apoB (from LDL) and apoA (thrombo-inflammatory aspects). Although conventional pharmacological therapies, such as statin, niacin, and cholesteryl ester transfer protein, have failed to significantly reduce Lp(a) levels, emerging new therapeutic strategies using proprotein convertase subtilisin-kexin type 9 inhibitors or antisesnse oligonucleotide technology have shown promising results in effectively lowering Lp(a). In this review we discuss the revisited important role of L(a) and strategies to overcome residual risk in the statin era.

Elevated Lipoprotein(a) and Risk of Ischemic Stroke

BACKGROUND

High lipoprotein(a) is associated with increased risk of myocardial infarction and aortic valve stenosis. Previous studies have examined the association of lipoprotein(a) and risk of stroke; however, the results are conflicting.

OBJECTIVES

The purpose of this study was to test if high lipoprotein(a) is associated with high risk of ischemic stroke observationally and causally from human genetics.

METHODS

The study included 49,699 individuals from the Copenhagen General Population Study and 10,813 individuals from the Copenhagen City Heart Study with measurements of plasma lipoprotein(a), LPA kringle-IV type 2 number of repeats, and LPA rs10455872. The endpoint of ischemic stroke was ascertained from Danish national health registries and validated by medical doctors.

RESULTS

Compared with individuals with lipoprotein(a) levels <10 mg/dl (<18 nmol/l: first to 50th percentile), the multivariable-adjusted hazard ratio for ischemic stroke was 1.60 (95% confidence interval [CI]:1.24 to 2.05) for individuals with lipoprotein(a) levels >93mg/dl (>199 nmol/L: 96th to 100th percentile). In observational analyses for a 50 mg/dl (105 nmol/l) higher lipoprotein(a) level the age- and sex-adjusted hazard ratio for ischemic stroke was 1.20 (95% CI: 1.13 to 1.28), while the corresponding age- and sex-adjusted genetic causal risk ratio for KIV-2 number of repeats was 1.20 (95% CI: 1.02 to 1.43) and for rs10455872 was 1.27 (95% CI: 1.06 to 1.51). The highest absolute 10-year risk of ischemic stroke was 17% in active smoking individuals >70 years of age with hypertension and lipoprotein(a) levels >93 mg/dl (>199 nmol/l: 96th to 100th percentile). In the Copenhagen City Heart Study, risk estimates for high levels of lipoprotein(a) were in the same direction but did not reach statistical significance.

CONCLUSIONS

In a large contemporary general population study, high plasma levels of lipoprotein(a) were associated with increased risk of ischemic stroke both observationally and causally from human genetics.

Lipoprotein(a) and Oxidized Phospholipids Promote Valve Calcification in Patients With Aortic Stenosis

Background

Lipoprotein(a) [Lp(a)], a major carrier of oxidized phospholipids (OxPL), is associated with an increased incidence of aortic stenosis (AS). However, it remains unclear whether elevated Lp(a) and OxPL drive disease progression and are therefore targets for therapeutic intervention.

Objectives

This study investigated whether Lp(a) and OxPL on apolipoprotein B-100 (OxPL-apoB) levels are associated with disease activity, disease progression, and clinical events in AS patients, along with the mechanisms underlying any associations.

Methods

This study combined 2 prospective cohorts and measured Lp(a) and OxPL-apoB levels in patients with AS (V_max >2.0 m/s), who underwent baseline ¹⁸F-sodium fluoride (¹⁸F-NaF) positron emission tomography (PET), repeat computed tomography calcium scoring, and repeat echocardiography. In vitro studies investigated the effects of Lp(a) and OxPL on valvular interstitial cells.

Results

Overall, 145 patients were studied (68% men; age 70.3 ± 9.9 years). On baseline positron emission tomography, patients in the top Lp(a) tertile had increased valve calcification activity compared with those in lower tertiles (n = 79; ¹⁸F-NaF tissue-to-background ratio of the most diseased segment: 2.16 vs. 1.97; p = 0.043). During follow-up, patients in the top Lp(a) tertile had increased progression of valvular computed tomography calcium score (n = 51; 309 AU/year [interquartile range: 142 to 483 AU/year] vs. 93 AU/year [interquartile range: 56 to 296 AU/year; p = 0.015), faster hemodynamic progression on echocardiography (n = 129; 0.23 ± 0.20 m/s/year vs. 0.14 ± 0.20 m/s/year] p = 0.019), and increased risk for aortic valve replacement and death (n = 145; hazard ratio: 1.87; 95% CI: 1.13 to 3.08; p = 0.014), compared with lower tertiles. Similar results were noted with OxPL-apoB. In vitro, Lp(a) induced osteogenic differentiation of valvular interstitial cells, mediated by OxPL and inhibited with the E06 monoclonal antibody against OxPL.

Conclusions

In patients with AS, Lp(a) and OxPL drive valve calcification and disease progression. These findings suggest lowering Lp(a) or inactivating OxPL may slow AS progression and provide a rationale for clinical trials to test this hypothesis.

Aortic valve calcification in the era of non-coding RNAs: The revolution to come in aortic stenosis management?

Aortic valve stenosis remains the most frequent structural heart disease, especially in the elderly. During the last decade, we noticed an important consideration and a huge number of publications related to the medical and surgical treatment of this disease. However, the molecular aspect of this degenerative issue has also been more widely studied recently. As evidenced in oncologic but also cardiac research fields, the emergence of microRNAs in the molecular screening and follow-up makes them potential biomarkers in the future, for the diagnosis, follow-up and treatment of aortic stenosis. Herein, we present a review on the implication of microRNAs in the aortic valve disease management. After listing and describing the main miRNAs of interest in the field, we provide an outline to develop miRNAs as innovative biomarkers and innovative therapeutic strategies, and describe a groundbreaking pre-clinical study using inhibitors of miR-34a in a pre-clinical model of aortic valve stenosis.