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

Consensus document on diagnosis and management of familial hypercholesterolemia from the Italian Society for the Study of Atherosclerosis (SISA)

AIMS

Familial Hypercholesterolemia (FH) is a genetic disorder of lipoprotein metabolism that causes an increased risk of premature atherosclerotic cardiovascular disease (ASCVD). Although early diagnosis and treatment of FH can significantly improve the cardiovascular prognosis, this disorder is underdiagnosed and undertreated. For these reasons the Italian Society for the Study of Atherosclerosis (SISA) assembled a Consensus Panel with the task to provide guidelines for FH diagnosis and treatment.

DATA SYNTHESIS

Our guidelines include: i) an overview of the genetic complexity of FH and the role of candidate genes involved in LDL metabolism; ii) the prevalence of FH in the population; iii) the clinical criteria adopted for the diagnosis of FH; iv) the screening for ASCVD and the role of cardiovascular imaging techniques; v) the role of molecular diagnosis in establishing the genetic bases of the disorder; vi) the current therapeutic options in both heterozygous and homozygous FH. Treatment strategies and targets are currently based on low-density lipoprotein cholesterol (LDL-C) levels, as the prognosis of FH largely depends on the magnitude of LDL-C reduction achieved by lipid-lowering therapies. Statins with or without ezetimibe are the mainstay of treatment. Addition of novel medications like PCSK9 inhibitors, ANGPTL3 inhibitors or lomitapide in homozygous FH results in a further reduction of LDL-C levels. LDL apheresis is indicated in FH patients with inadequate response to cholesterol-lowering therapies.

CONCLUSION

FH is a common, treatable genetic disorder and, although our understanding of this disease has improved, many challenges still remain with regard to its identification and management.

Ancestry specific distribution of LPA Kringle IV-Type-2 genetic variants highlight associations to apo(a) copy number, glucose, and hypertension

Background

High Lp(a) levels contribute to atherosclerotic cardiovascular disease and are tightly regulated by the LPA gene. Lp(a) levels have an inverse correlation with LPA Kringle IV Type-2 (KIV-2) copy number (CN). Black (B) and Hispanic (H) individuals exhibit higher levels of Lp(a), and rates of CVD compared to non-Hispanic Whites (NHW). Therefore, we investigated genetic variations in the LPA KIV-2 region across three ancestries and their associations with metabolic risk factors.

Methods

Using published pipelines, we analyzed a multi-ethnic whole exome dataset comprising 3,817 participants from the Washington Heights and Inwood Columbia Aging Project (WHICAP): 886 [NHW (23%), 1,811 Caribbean (C) H (47%), and 1,120 B individuals (29%). Rare and common variants (alternative allele carrier frequency, CF < 0.01 or > 0.99 and 0.01 < CF < 0.99, respectively) were identified and KIV-2 CN estimated. The associations of variants and CN with history of heart disease, hypertension (HTN), stroke, lipid levels and clinical diagnosis of Alzheimer's disease (AD) was assessed. A small pilot provided in-silico validation of study findings.

Results

We report 1421 variants in the LPA KIV-2 repeat region, comprising 267 exonic and 1154 intronic variants. 61.4% of the exonic variants have not been previously described. Three novel exonic variants significantly increase the risk of HTN across all ethnic groups: 4785-C/A (frequency = 78%, odds ratio [OR] = 1.45, p = 0.032), 727-T/C (frequency = 96%, OR = 2.11, p = 0.032), and 723-A/G (frequency = 96%, OR = 1.97, p = 0.038). Additionally, six intronic variants showed associations with HTN: 166-G/A, 387-G/C, 402-G/A, 4527-A/T, 4541-G/A, and 4653-A/T. One intronic variant, 412-C/T, was associated with decreased blood glucose levels (frequency = 72%, β = -14.52, p = 0.02). Three of the associations were not affected after adjusting for LPA KIV-2 CN: 412-C/T (β = -14.2, p = 0.03), 166-G/A (OR = 1.41, p = 0.05), and 387-G/C (OR = 1.40, p = 0.05). KIV CN itself was significantly associated with 314 variants and was negatively correlated with plasma total cholesterol levels.

Conclusions

In three ancestry groups, we identify novel rare and common LPA KIV-2 region variants. We report new associations of variants with HTN and Glucose levels. These results underscore the genetic complexity of the LPA KIV-2 region in influencing cardiovascular and metabolic health, suggesting potential genetic regulation of pathways that can be studied for research and therapeutic interventions.

Clinical Perspective

Lp(a) levels are mostly controlled by the LPA gene and are higher in Blacks and Hispanics. Novel LPA KIV-2 variants found in three ancestry groups, including data on Caribbean Hispanics, show strong positive associations to hypertension and negative associations to glucose levels. Further characterization of these variants and identifying links to disease can help precision medicine efforts to understand disease mechanisms in all populations.

Consensus on lipoprotein(a) of the Spanish Society of Arteriosclerosis. Literature review and recommendations for clinical practice

The irruption of lipoprotein(a) (Lp(a)) in the study of cardiovascular risk factors is perhaps, together with the discovery and use of proprotein convertase subtilisin/kexin type 9 (iPCSK9) inhibitor drugs, the greatest novelty in the field for decades. Lp(a) concentration (especially very high levels) has an undeniable association with certain cardiovascular complications, such as atherosclerotic vascular disease (AVD) and aortic stenosis. However, there are several current limitations to both establishing epidemiological associations and specific pharmacological treatment. Firstly, the measurement of Lp(a) is highly dependent on the test used, mainly because of the characteristics of the molecule. Secondly, Lp(a) concentration is more than 80% genetically determined, so that, unlike other cardiovascular risk factors, it cannot be regulated by lifestyle changes. Finally, although there are many promising clinical trials with specific drugs to reduce Lp(a), currently only iPCSK9 (limited for use because of its cost) significantly reduces Lp(a). However, and in line with other scientific societies, the SEA considers that, with the aim of increasing knowledge about the contribution of Lp(a) to cardiovascular risk, it is relevant to produce a document containing the current status of the subject, recommendations for the control of global cardiovascular risk in people with elevated Lp(a) and recommendations on the therapeutic approach to patients with elevated Lp(a).

High lipoprotein(a): Actionable strategies for risk assessment and mitigation

High levels of lipoprotein(a) [Lp(a)] are causal for atherosclerotic cardiovascular disease (ASCVD). Lp(a) is the most prevalent inherited dyslipidemia and strongest genetic ASCVD risk factor. This risk persists in the presence of at target, guideline-recommended, LDL-C levels and adherence to lifestyle modifications. Epidemiological and genetic evidence supporting its causal role in ASCVD and calcific aortic stenosis continues to accumulate, although various facets regarding Lp(a) biology (genetics, pathophysiology, and expression across race/ethnic groups) are not yet fully understood. The evolving nature of clinical guidelines and consensus statements recommending universal measurements of Lp(a) and the scientific data supporting its role in multiple disease states reinforce the clinical merit to start population screening for Lp(a) now. There is a current gap in the implementation of recommendations for primary and secondary cardiovascular disease (CVD) prevention in those with high Lp(a), in part due to a lack of protocols for management strategies. Importantly, targeted apolipoprotein(a) [apo(a)]-lowering therapies that reduce Lp(a) levels in patients with high Lp(a) are in phase 3 clinical development. This review focuses on the identification and clinical management of patients with high Lp(a). Specifically, we highlight the clinical value of measuring Lp(a) and its use in determining Lp(a)-associated CVD risk by providing actionable guidance, based on scientific knowledge, that can be utilized now to mitigate risk caused by high Lp(a).

Lipoprotein(a) and cardiovascular disease: sifting the evidence to guide future research

Lipoprotein(a) (Lp(a)) is a genetically determined causal risk factor for cardiovascular disease including coronary heart disease, peripheral arterial disease, ischaemic stroke, and calcific aortic valve stenosis. Clinical trials of specific and potent Lp(a)-lowering drugs are currently underway. However, in clinical practice, widespread assessment of Lp(a) is still lacking despite several guideline recommendations to measure Lp(a) at least once in a lifetime in all adults to identify those at high or very high risk due to elevated levels. The present review provides an overview of key findings from observational and genetic Lp(a) studies, highlights the main challenges in observational Lp(a) studies, and proposes a minimum set of requirements to enhance the quality and harmonize the collection of Lp(a)-related data. Adherence to the recommendations set forth in the present manuscript is intended to enhance the quality of future observational Lp(a) studies, to better define thresholds for increased risk, and to better inform clinical trial design. The recommendations can also potentially assist in the interpretation and generalization of clinical trial findings, to improve care of patients with elevated Lp(a) and optimize treatment and prevention of cardiovascular disease.

Lipoprotein(a): from Causality to Treatment

PURPOSE OF REVIEW

This paper reviews the evidence why lipoprotein(a) (Lp(a)) is a causal risk factor for cardiovascular disease and how high Lp(a) concentrations should be managed now and with an outlook to the future.

REVIEW FINDINGS

No optimal and widely available animal models exist to study the causality of the association between Lp(a) and cardiovascular disease. This has been a major handicap for the entire field. However, genetic studies turned the page. Already in the early 1990s, the principle of Mendelian randomization studies was applied for the first time ever (even if they were not named so at that time). Genetic variants of the LPA gene such as the apolipoprotein(a) isoform size, the number and sum of kringle IV repeats and later single nucleotide polymorphisms are strongly associated with life-long exposure to high Lp(a) concentrations as well as cardiovascular outcomes. This evidence provided a basis for the development of specific Lp(a)-lowering drugs that are currently in clinical testing phase. Lp(a) is one of the most important genetically determined risk factors for cardiovascular disease. With the specific Lp(a)-lowering therapies, we might get tools to fight this common risk factor in case the outcome trials will be positive.

Lipoprotein(a) levels and carotid intima-media thickness in children: A 20-year follow-up study

Elevated lipoprotein(a) [Lp(a)] is independently associated with cardiovascular disease (CVD). In a recent long-term follow-up study involving children with familial hypercholesterolemia (FH), Lp(a) levels contributed significantly to early atherosclerosis, as measured by carotid intima-media thickness (cIMT). To determine if this holds true for children without FH, we conducted a 20-year follow-up study, examining 88 unaffected siblings (mean age: 12.9 years) of children with FH. No significant association was found between Lp(a) and cIMT during follow-up (ß-adjusted [95% confidence interval] = 0.0001 [-0.008 to 0.008] mm per 50 nmol/L increase Lp(a), p = 0.97). In conclusion, our findings suggest that elevated levels of Lp(a) do not play a significant role in arterial wall thickening among children without FH during the 20-year follow-up period. This leads us to consider the possibility that cIMT may not be a suitable marker for detecting potential subtle changes in the arterial wall mediated by Lp(a) in the young, general population. However, it could also be that elevated Lp(a) is only a significant risk factor for atherosclerosis in the presence of other risk factors such as FH.

Lifestyle and Lipoprotein(a) Levels: Does a Specific Counseling Make Sense?

Lipoprotein(Lp)(a) is a variant of low-density lipoprotein (LDL), bound to apolipoprotein B100, whose levels are associated with a significant increase in the risk of atherosclerosis-related cardiovascular events, but also to aortic stenosis and atrial fibrillation. Since plasma levels of Lp(a) are commonly considered resistant to lifestyle changes, we critically reviewed the available evidence on the effect of weight loss, dietary supplements, and physical activity on this risk factor. In our review, we observed that relevant body weight loss, a relatively high intake of saturated fatty acids, the consumption of red wine, and intense physical exercise seems to be associated with significantly lower plasma Lp(a) levels. On the contrary, foods rich in trans-unsaturated fatty acids are associated with increased Lp(a) levels. With regard to dietary supplements, coenzyme Q10, L-Carnitine, and flaxseed exert a mild but significant lowering effect on plasma Lp(a).

The association of lipoprotein (a) with coronary artery calcification: A systematic review and meta-analysis

BACKGROUND AND AIMS

Coronary artery calcification (CAC) is a crucial pathophysiological characteristic of atherosclerosis. The association between lipoprotein (a) [Lp(a)] and CAC is inconsistent. We aimed to assess the relationship between Lp(a) and CAC by exploring the association between elevated Lp(a) and CAC prevalence, the relationship between Lp(a) level and CAC prevalence, and the correlation between elevated Lp(a) and CAC progression.

METHODS

We searched the PubMed, Web of Science, and EMBASE databases up to November 01, 2023. Studies exploring the association between serum Lp(a) and CAC (quantified using the Agatston score) were included. Association between Lp(a) level or elevated Lp(a) (higher than the cutoff values of 30 mg/dL, 50 mg/dL, or the highest quartile ranging from 33 to 38.64 mg/dL) and prevalence [CAC score >0 or >100, log (CAC score+1) >0] or progression (an increase in CAC score >0 or ≥100) of CAC were analysed. Odds ratios and 95% confidence intervals were calculated using a random-effects model.

RESULTS

40,073 individuals from 17 studies were included. Elevated Lp(a) was associated with a higher prevalence of CAC (OR, 1.31; 95% CI, 1.06 to 1.61; p = 0.01). As a continuous variable, Lp(a) level was positively correlated with the prevalence of CAC (OR, 1.05; 95% CI, 1.02 to 1.08; p = 0.003). Furthermore, elevated Lp(a) was associated with greater CAC progression (OR, 1.54; 95% CI, 1.23 to 1.92; p = 0.0002).

CONCLUSIONS

This meta-analysis suggested that Lp(a) is associated with prevalence and progression of CAC. Further studies are required to explore whether Lp(a)-lowering therapy could prevent or inhibit CAC, ultimately reducing coronary artery disease risk.

Measuring lipoprotein(a) for cardiovascular disease prevention - in whom and when?

PURPOSE OF REVIEW

The aim of this study is to summarize major cardiovascular guideline recommendations on lipoprotein(a) and highlighting recent findings that emphasize how measuring lipoprotein(a) once in all adults is meaningful regardless of age, sex, comorbidities, or ethnicity.

RECENT FINDINGS

Many international guidelines now recommend once in a lifetime measurement of lipoprotein(a) in all adult individuals to facilitate accurate risk prediction. Lipoprotein(a)-lowering therapy to reduce cardiovascular disease is on the horizon, with results from the first phase 3 trial expected in 2025.

SUMMARY

Elevated lipoprotein(a) is an independent causal risk factor for atherosclerotic cardiovascular disease and aortic valve stenosis and measuring lipoprotein(a) once in all individuals regardless of age, sex, comorbidities, or ethnicity is meaningful to aid in risk stratification.

Healthy lifestyle, lipoprotein (a) levels and the risk of coronary artery disease

BACKGROUND

Lipoprotein (a) [Lp(a)] is associated with coronary artery disease (CAD). However, the role of healthy lifestyle against the risk of CAD with consideration of high Lp(a) levels remains unclear.

METHODS

This study examined 4512 participants who underwent serum Lp(a) level assessment at Kanazawa University Hospital from 2008 to March 2016. Their lifestyle habits were examined based on four questionnaires regarding dietary pattern, exercise habits, smoking status and body weight. Logistic regression analyses were performed to identify the association between healthy lifestyle and CAD independent of Lp(a) levels.

RESULTS

The Lp(a) levels were significantly associated with CAD (odds ratio [OR]: 1.12, 95% confidence interval [CI]: 1.08-1.17, p = 1.3 × 10-7 per 10 mg/dL). Under these circumstances, the lifestyle risk score was also significantly associated with CAD (OR: 1.24, 95% CI: 1.12-1.36, p = 2.4 × 10-8 ). Compared with patients with a favourable lifestyle who have Lp(a) levels of <30 mg/dL, those with an intermediate or unfavourable lifestyle were at higher risk for CAD (OR: 1.11, 95% CI: 1.02-1.20, p = 0.003 and OR: 1.40, 95% CI: 1.16-1.54, p = 3.6 × 10-5 , respectively). Further, patients with a favourable, intermediate or unfavourable lifestyle who have Lp(a) levels of ≥30 mg/dL were at high risk for CAD (OR: 1.21, 95% CI: 1.08-1.34, p = 0.0014; OR: 1.31, 95% CI: 1.14-1.48, p = 1.2 × 10-4 ; and OR: 1.81, 95% CI: 1.44-2.18, p = 2.2 × 10-7 , respectively).

CONCLUSIONS

Healthy lifestyle was associated with a lower risk of CAD regardless of Lp(a) levels.

Estimating the Prevalence and Characteristics of Patients Potentially Eligible for Lipoprotein(a)-Lowering Therapies in a Real-World Setting

High lipoprotein(a) (Lp(a)) plasma levels are significantly associated with an increased risk of developing atherosclerotic cardiovascular diseases (ASCVD). The aim of this analysis was to estimate the prevalence and characteristics of patients potentially eligible for Lp(a)-lowering therapies in a real-world setting (i.e., patients with ASCVD and Lp(a) levels > 70 mg/dL). For this reason, we pooled data from a large cohort of Italian outpatients (N = 5961; men: 2879, women: 3982) with dyslipidemia. A binary logistic regression analysis was used to determine the significant predictors of ASCVD in the cohort, which were age (Odds Ratio (OR): 1.158, 95% Confidence Interval (CI): 1.114 to 1.203, p < 0.001), low-density lipoprotein cholesterol at entry (OR: 1.989, 95% CI: 1.080 to 1.198, p = 0.020) and Lp(a) (OR: 1.090, 95% CI: 1.074 to 1.107, p < 0.001). In our cohort, almost half of patients with ASCVD (44.7%) may be eligible to be treated with Lp(a)-lowering agents. Interestingly, patients who do not meet the treatment criteria despite high Lp(a) (50-70 mg/dL), respectively, account for 4.7% and 7.3% of those in primary and secondary ASCVD prevention. In conclusion, in our large cohort of outpatients with dyslipidemia, the prevalence of individuals with ASCVD and very high Lp(a) plasma levels is quite high, even with a conservative estimation.

Lipoprotein(a) and Risks of Peripheral Artery Disease, Abdominal Aortic Aneurysm, and Major Adverse Limb Events

BACKGROUND

Lp(a) (lipoprotein[a])-lowering therapy to reduce cardiovascular disease is under investigation in phase 3 clinical trials. High Lp(a) may be implicated in peripheral artery disease (PAD), abdominal aortic aneurysms (AAAs), and major adverse limb events (MALE).

OBJECTIVES

The authors investigated the association of high Lp(a) levels and corresponding LPA genotypes with risk of PAD, AAA, and MALE.

METHODS

The authors included 108,146 individuals from the Copenhagen General Population Study. During follow-up, 2,450 developed PAD, and 1,251 AAAs. Risk of MALE was assessed in individuals with PAD at baseline and replicated in the Copenhagen City Heart Study.

RESULTS

Higher Lp(a) was associated with a stepwise increase in risk of PAD and AAA (P for trend <0.001). For individuals with Lp(a) levels ≥99th (≥143 mg/dL, ≥307 nmol/L) vs <50th percentile (≤9 mg/dL, ≤17 nmol/L), multivariable-adjusted HRs were 2.99 (95% CI: 2.09-4.30) for PAD and 2.22 (95% CI: 1.21-4.07) for AAA. For individuals with PAD, the corresponding incidence rate ratio for MALE was 3.04 (95% CI: 1.55-5.98). Per 50 mg/dL (105 nmol/L) genetically higher Lp(a) risk ratios were 1.39 (95% CI: 1.24-1.56) for PAD and 1.21 (95% CI: 1.01-1.44) for AAA, consistent with observational risk ratios of 1.33 (95% CI: 1.24-1.43) and 1.27 (95% CI: 1.15-1.41), respectively. In women smokers aged 70 to 79 years with Lp(a) <50th and ≥99th percentile, absolute 10-year risks of PAD were 8% and 21%, and equivalent risks in men 11% and 29%, respectively. For AAA, corresponding risks were 2% and 4% in women, and 5% and 12% in men.

CONCLUSIONS

High Lp(a) levels increased risk of PAD, AAA, and MALE by 2- to 3-fold in the general population, opening opportunities for prevention given future Lp(a)-lowering therapies.

Novel lipid biomarkers and ratios as risk predictors for premature coronary artery disease: A retrospective analysis of 2952 patients

This study examined the associations between emerging lipid biomarkers (small dense low-density lipoprotein cholesterol [sdLDL-C), lipoprotein(a) [Lp(a)], and free fatty acids [FFA]), two ratios (sdLDL-C/LDL-C and the triglyceride-glucose [TyG) index), and the Gensini score (GS) in patients with premature coronary artery disease (PCAD) in relation to the extent of coronary stenosis. The authors evaluated a cohort of 2952 individuals undergoing coronary angiography (CAG), encompassing those with PCAD (n = 1749), late-onset coronary artery disease (LCAD; n = 328), and non-coronary artery disease (non-CAD; n = 575). Noteworthy differences were observed in the levels of the novel lipid biomarkers and ratio indexes among the PCAD, LCAD, and non-CAD groups (p < .05). Multiple logistic regression analyses pinpointed Lp(a) (OR = 2.62, 95% CI 1.22-5.63, p = .014) and the TyG index (OR = 2.53, 95% CI 1.08-5.93, p = .033) as independent risk factors for PCAD. Furthermore, these biomarkers and ratio indexes discerned substantial distinctions among PCAD patients with varying GS (p < .05). Consequently, these markers can proficiently anticipate the gravity of coronary artery stenosis (GS > 40) in PCAD patients, as evidenced by the ROC analysis. In conclusion, sdLDL-C, Lp(a), FFA, and the sdLDL-C/LDL-C and TyG indexes have considerable potential as risk and diagnostic markers for coronary artery stenosis in individuals afflicted with PCAD.

Lipoprotein(a): a genetically determined risk factor for Cardiovascular disease

Lipoprotein(a) is a complex lipoprotein with unique characteristics distinguishing it from all the other apolipoprotein B-containing lipoprotein particles. Its lipid composition and the presence of a single molecule of apolipoprotein B per particle, render lipoprotein(a) similar to low-density lipoproteins. However, the presence of a unique, carbohydrate-rich protein termed apolipoprotein(a), linked by a covalent bond to apolipoprotein B imparts unique characteristics to lipoprotein(a) distinguishing it from all the other lipoproteins. Apolipoprotein(a) is highly polymorphic in size ranging in molecular weight from <300 KDa to >800 kDa. Both the size polymorphism and the concentration of lipoprotein(a) in plasma are genetically determined and unlike other lipoproteins, plasma concentration is minimally impacted by lifestyle modifications or lipid-lowering drugs. Many studies involving hundreds of thousands of individuals have provided strong evidence that elevated lipoprotein(a) is genetically determined and a causal risk factor for atherosclerotic cardiovascular disease. The concentration attained in adulthood is already present in children at around 5 years of age and therefore, those with elevated lipoprotein(a) are prematurely exposed to a high risk of cardiovascular disease. Despite the large number of guidelines and consensus statements on the management of lipoprotein(a) in atherosclerotic cardiovascular disease published in the last decade, lipoprotein(a) is still seldom measured in clinical settings. In this review, we provide an overview of the most important features that characterize lipoprotein(a), its role in cardiovascular disease, and the importance of adding the measurement of lipoprotein(a) for screening adults and youths to identify those at increased risk of atherosclerotic cardiovascular disease due to their elevated plasma concentration of lipoprotein(a).

Lifestyle patterns, genetic susceptibility, and risk of valvular heart disease: a prospective cohort study based on the UK Biobank

AIMS

Genetic and lifestyle factors are both major contributors to valvular heart disease (VHD). However, it is still uncertain whether genetic susceptibility alters the association between lifestyle and VHD. We aimed to investigate the association between lifestyle and VHD in different genetic risk backgrounds.

METHODS AND RESULTS

A prospective cohort study was carried out on 499 341 participants without VHD at baseline. The assessment of lifestyle included smoking, alcohol consumption, diet, activity, and sleep. Genetic susceptibility was separately measured by polygenic risk scores (PRSs) and family history of cardiovascular disease (CVD). Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95%CIs) between lifestyle and VHD, as well as aortic stenosis (AS). During a median follow-up of 10.8 years, 12 983 incident VHD cases were diagnosed (incidence rate 2.46 per 1000 person-years), including 3527 AS cases (incidence rate 0.66 per 1000 person-years). The risk of VHD and AS decreased with healthier lifestyles (P value for trend <0.001). Compared to individuals with a unhealthy lifestyle, the HRs of VHD in intermediate and healthy lifestyle groups were 0.81 (0.76-0.86) and 0.81 (0.76-0.87). The negative association between healthy lifestyle and VHD events was independent of genetic risk (P for interaction between healthy lifestyle scores and PRSs/family history of CVD was 0.723/0.763). Similar findings were obtained in analyses of AS, and a stronger negative association was found.

CONCLUSION

Our study reveals that adherence to a healthy lifestyle is significantly associated with a reduced risk of VHD especially AS, irrespective of genetic susceptibility.

SUMMARY

Based on a cohort of around 490 000 participants, the study investigated the association between lifestyle and VHD under different stratifications of genetic risk. The study found that a healthy lifestyle was associated with a lower risk of VHD, particularly AS, independent of genetic risk. Our findings suggest that advance interventions for lifestyle may be an effective way to reduce the global burden of VHD.

Contribution of Lipoprotein(a) to Polygenic Risk Prediction of Coronary Artery Disease: A Prospective UK Biobank Analysis

BACKGROUND

Lp(a) (lipoprotein[a]) is a highly atherogenic lipoprotein subfraction that may contribute to polygenic risk of coronary artery disease (CAD), but the extent of this contribution is unknown. Our objective was to estimate the contribution of Lp(a) to polygenic risk of CAD and to evaluate the respective contributions of Lp(a) and a CAD polygenic risk score (PRS) to CAD.

METHODS

A total of 372 385 UK Biobank participants of European ancestry free of CAD at baseline were included. Plasma Lp(a) levels were measured and a CAD-PRS was calculated using the LDpred2 algorithm. Over the median follow-up of 12.6 years, 13 538 participants had incident CAD (myocardial infarction, coronary artery bypass grafting, or coronary angioplasty).

RESULTS

The LPA region contribution to the CAD-PRS-mediated CAD risk was modest (7.2% [95% CI, 6.1-8.3]). Lp(a) levels significantly increased the predictive performance of a CAD-PRS including age and sex in Cox regression (C statistic 0.751 versus 0.746, difference, 0.005 [95% CI, 0.004-0.006]). Compared with participants in the bottom CAD-PRS quintile with Lp(a) levels <25 nmol/L (CAD event rate, 1.4%), the hazard ratio for incident CAD in participants in the top CAD-PRS quintile with Lp(a) levels ≥125 nmol/L was 5.45 (95% CI, 4.93-6.03; P=9.35×10-242, CAD event rate 6.6%).

CONCLUSIONS

Compared with individuals with a low genetic risk of CAD (low CAD-PRS and low Lp[a] levels), those with a high genetic risk (high CAD-PRS and high Lp[a] levels) had a 5-fold higher CAD risk. These results highlight a substantial contribution of genetic risk factors to CAD and that accurate estimation of genetic risk of CAD may need to consider blood levels of Lp(a).

Assessment of Apolipoprotein(a) Isoform Size Using Phenotypic and Genotypic Methods

Apolipoprotein(a) (apo(a)) is the protein component that defines lipoprotein(a) (Lp(a)) particles and is encoded by the LPA gene. The apo(a) is extremely heterogeneous in size due to the copy number variations in the kringle-IV type 2 (KIV2) domains. In this review, we aim to discuss the role of genetics in establishing Lp(a) as a risk factor for coronary heart disease (CHD) by examining a series of molecular biology techniques aimed at identifying the best strategy for a possible application in clinical research and practice, according to the current gold standard.

Lipoprotein(a) as a Risk Factor for Cardiovascular Diseases: Pathophysiology and Treatment Perspectives

Cardiovascular disease (CVD) is still a leading cause of morbidity and mortality, despite all the progress achieved as regards to both prevention and treatment. Having high levels of lipoprotein(a) [Lp(a)] is a risk factor for cardiovascular disease that operates independently. It can increase the risk of developing cardiovascular disease even when LDL cholesterol (LDL-C) levels are within the recommended range, which is referred to as residual cardiovascular risk. Lp(a) is an LDL-like particle present in human plasma, in which a large plasminogen-like glycoprotein, apolipoprotein(a) [Apo(a)], is covalently bound to Apo B100 via one disulfide bridge. Apo(a) contains one plasminogen-like kringle V structure, a variable number of plasminogen-like kringle IV structures (types 1-10), and one inactive protease region. There is a large inter-individual variation of plasma concentrations of Lp(a), mainly ascribable to genetic variants in the Lp(a) gene: in the general po-pulation, Lp(a) levels can range from <1 mg/dL to >1000 mg/dL. Concentrations also vary between different ethnicities. Lp(a) has been established as one of the risk factors that play an important role in the development of atherosclerotic plaque. Indeed, high concentrations of Lp(a) have been related to a greater risk of ischemic CVD, aortic valve stenosis, and heart failure. The threshold value has been set at 50 mg/dL, but the risk may increase already at levels above 30 mg/dL. Although there is a well-established and strong link between high Lp(a) levels and coronary as well as cerebrovascular disease, the evidence regarding incident peripheral arterial disease and carotid atherosclerosis is not as conclusive. Because lifestyle changes and standard lipid-lowering treatments, such as statins, niacin, and cholesteryl ester transfer protein inhibitors, are not highly effective in reducing Lp(a) levels, there is increased interest in developing new drugs that can address this issue. PCSK9 inhibitors seem to be capable of reducing Lp(a) levels by 25-30%. Mipomersen decreases Lp(a) levels by 25-40%, but its use is burdened with important side effects. At the current time, the most effective and tolerated treatment for patients with a high Lp(a) plasma level is apheresis, while antisense oligonucleotides, small interfering RNAs, and microRNAs, which reduce Lp(a) levels by targeting RNA molecules and regulating gene expression as well as protein production levels, are the most widely explored and promising perspectives. The aim of this review is to provide an update on the current state of the art with regard to Lp(a) pathophysiological mechanisms, focusing on the most effective strategies for lowering Lp(a), including new emerging alternative therapies. The purpose of this manuscript is to improve the management of hyperlipoproteinemia(a) in order to achieve better control of the residual cardiovascular risk, which remains unacceptably high.

Lipoprotein(a) and carotid intima-media thickness in children with familial hypercholesterolaemia in the Netherlands: a 20-year follow-up study

BACKGROUND

Elevated lipoprotein(a) and familial hypercholesterolaemia are both independent risk conditions for cardiovascular disease. Although signs of atherosclerosis can be observed in children with familial hypercholesterolaemia, it is unknown whether elevated lipoprotein(a) is an additional risk factor for atherosclerosis in these young patients. Therefore, we aimed to assess the contribution of lipoprotein(a) concentrations to arterial wall thickening (as measured by carotid intima-media thickness) in children with familial hypercholesterolaemia who were followed up into adulthood.

METHODS

We conducted a 20-year follow-up study of 214 children (aged 8-18 years) with heterozygous familial hypercholesterolaemia who were randomly assigned in a statin trial in Amsterdam (Netherlands) between Dec 7, 1997, and Oct 4, 1999. At baseline, and at 2, 10, and 20 years thereafter, blood samples were taken and carotid intima-media thickness was measured. Linear mixed-effects models were used to evaluate the association between lipoprotein(a) and carotid intima-media thickness during follow-up. We adjusted for sex, age, corrected LDL-cholesterol, statin use, and BMI.

FINDINGS

Our study population comprised 200 children who had a carotid intima-media thickness measurement and a measured lipoprotein(a) concentration from at least one visit available. Mean age at baseline was 13·0 years (SD 2·9), 106 (53%) children were male, and 94 (47%) were female. At baseline, median lipoprotein(a) concentration was 18·5 nmol/L (IQR 8·7-35·5) and mean carotid intima-media thickness was 0·4465 mm (SD 0·0496). During follow-up, higher lipoprotein(a) concentrations contributed significantly to progression of carotid intima-media thickness (β adjusted 0·0073 mm per 50 nmol/L increase in lipoprotein(a) [95% CI 0·0013-0·0132]; p=0·017).

INTERPRETATION

Our findings suggest that lipoprotein(a) concentrations contribute significantly to arterial wall thickening in children with familial hypercholesterolaemia who were followed-up until adulthood, suggesting that lipoprotein(a) is an independent and additional risk factor for early atherosclerosis in those already at increased risk. Lipoprotein(a) measurement in young patients with familial hypercholesterolaemia is crucial to identify those at potentially highest risk for cardiovascular disease.

FUNDING

Silence Therapeutics.

Daring to dream: Targeting lipoprotein(a) as a causal and risk-enhancing factor

Lipoprotein(a) [Lp(a)], a distinct lipoprotein class, has become a major focus for cardiovascular research. This review is written in light of the recent guideline and consensus statements on Lp(a) and focuses on 1) the causal association between Lp(a) and cardiovascular outcomes, 2) the potential mechanisms by which elevated Lp(a) contributes to cardiovascular diseases, 3) the metabolic insights on the production and clearance of Lp(a) and 4) the current and future therapeutic approaches to lower Lp(a) concentrations. The concentrations of Lp(a) are under strict genetic control. There exists a continuous relationship between the Lp(a) concentrations and risk for various endpoints of atherosclerotic cardiovascular disease (ASCVD). One in five people in the Caucasian population is considered to have increased Lp(a) concentrations; the prevalence of elevated Lp(a) is even higher in black populations. This makes Lp(a) a cardiovascular risk factor of major public health relevance. Besides the association between Lp(a) and myocardial infarction, the relationship with aortic valve stenosis has become a major focus of research during the last decade. Genetic studies provided strong support for a causal association between Lp(a) and cardiovascular outcomes: carriers of genetic variants associated with lifelong increased Lp(a) concentration are significantly more frequent in patients with ASCVD. This has triggered the development of drugs that can specifically lower Lp(a) concentrations: mRNA-targeting therapies such as anti-sense oligonucleotide (ASO) therapies and short interfering RNA (siRNA) therapies have opened new avenues to lower Lp(a) concentrations more than 95%. Ongoing Phase II and III clinical trials of these compounds are discussed in this review.

Frequent questions and responses on the 2022 lipoprotein(a) consensus statement of the European Atherosclerosis Society

In 2022, the European Atherosclerosis Society (EAS) published a new consensus statement on lipoprotein(a) [Lp(a)], summarizing current knowledge about its causal association with atherosclerotic cardiovascular disease (ASCVD) and aortic stenosis. One of the novelties of this statement is a new risk calculator showing how Lp(a) influences lifetime risk for ASCVD and that global risk may be underestimated substantially in individuals with high or very high Lp(a) concentration. The statement also provides practical advice on how knowledge about Lp(a) concentration can be used to modulate risk factor management, given that specific and highly effective mRNA-targeted Lp(a)-lowering therapies are still in clinical development. This advice counters the attitude: "Why should I measure Lp(a) if I can't lower it?". Subsequent to publication, questions have arisen relating to how the recommendations of this statement impact everyday clinical practice and ASCVD management. This review addresses 30 of the most frequently asked questions about Lp(a) epidemiology, its contribution to cardiovascular risk, Lp(a) measurement, risk factor management and existing therapeutic options.

Lipoprotein(a) levels in children with homozygous familial hypercholesterolaemia: A cross-sectional study

Homozygous familial hypercholesterolaemia (HoFH) is a life-threatening disorder characterized by extremely elevated low-density lipoprotein cholesterol (LDL-C) levels. Untreated, severe atherosclerotic cardiovascular disease (ASCVD), including aortic valve stenosis (AVS), may already occur in childhood. Another important genetic risk factor for ASCVD and AVS is elevated lipoprotein(a) [Lp(a)], which is highly prevalent in the general paediatric population. However, data on Lp(a) in children with HoFH are scarce. Therefore, we performed a cross-sectional study to evaluate Lp(a) levels in children with HoFH and compared them to children with heterozygous FH (HeFH) and unaffected children. Adjusted least-square mean (95% CI) Lp(a) levels in HoFH (n=29), HeFH (n=101) and unaffected children (n=102) were 18.7 (12.0-29.1), 15.3 (11.8-19.8) and 10.5 (8.3-13.2) mg/dL, respectively (p-for-trend=0.007). Lp(a) levels in children with HoFH were higher than in children with HeFH and in unaffected children. Given the very high ASCVD risk with HoFH, identifying other risk factors such as elevated Lp(a) in these children is important. Therefore, Lp(a) levels should be measured at least once in all children with HoFH.

Detection strategies for elevated lipoprotein(a): will implementation let the genie out of the bottle?

PURPOSE OF REVIEW

Elevated Lp(a) level is an important causal risk factor for atherosclerotic cardiovascular disease (ASCVD), principally coronary artery disease. Selective testing for Lp(a) is highly recommended in patients at intermediate and high risk for ASCVD. Lp(a) levels are predominantly genetically determined, and this has implications for cascade testing.

RECENT FINDINGS

Recent studies show that cascade testing is effective in identifying elevated Lp(a) in close relatives of probands with high Lp(a). Apart from selective testing and cascade testing as detection strategies, some recent guidelines recommend testing of Lp(a) in all adults at least once in their lifetime and various implementation strategies have been suggested.

SUMMARY

Hyper-Lp(a) is an important global health problem that can be easily detected. Hyper-Lp(a) meets all the criteria for universal screening except that there is not yet supportive evidence from clinical interventional trials showing a reduction of ASCVD events. The cost-effectiveness of the various detection and implementation strategies need to be further evaluated.

Extreme lipoprotein(a) in clinical practice: A cross sectional study

Introduction

Measurement of lipoprotein(a) [Lp(a)] is recommended once in a lifetime to identify individuals at high risk of atherosclerotic cardiovascular disease (ASCVD). We aimed to analyze the clinical features of patients with extreme Lp(a).

Methods

Cross-sectional, case-control study of a single healthcare organization between 2015 and 2021. Individuals with extreme Lp(a) > 430 nmol/L (53 of 3900 tested patients) were compared to age- and sex-matched controls with normal range Lp(a).

Results

Mean patient age was 58 ± 14 years (49% women). Myocardial infarction (47.2% vs. 18.9%), coronary artery disease (CAD) (62.3% vs. 28.3%), and peripheral artery disease (PAD) or stroke (22.6% vs. 11.3%) were more prevalent in patients with extreme than normal range Lp(a). The adjusted odds ratio [95% confidence interval (CI)] associated with extreme compared to normal range Lp(a) was 2.50 (1.20-5.21) for myocardial infarction, 2.20 (1.20-4.05) for CAD, and 2.75 (0.88-8.64) for PAD or stroke. A high-intensity statin plus ezetimibe combination was issued by 33% and 20% of CAD patients with extreme and normal range Lp(a), respectively. In patients with CAD, low density lipoprotein cholesterol (LDL-C) <55 mg/dL was achieved in 36% of those with extreme Lp(a) and 47% of those with normal range Lp(a).

Conclusions

Extremely elevated Lp(a) levels are associated with an approximately 2.5-fold increased risk of ASCVD compared with normal range Lp(a) levels. Although lipid-lowering treatment is more intense in CAD patients with extreme Lp(a), combination therapies are underused, and attainment rates of LDL-C goals are suboptimal.

Lipoprotein(a), Cardiovascular Events and Sex Differences: A Single Cardiological Unit Experience

Lipoprotein(a)-Lp(a), which retains proatherogenic and prothrombotic properties, may be modified by hormonal and metabolic factors. However, few studies have focused on differences related to sex and cardiometabolic risk factors in the relationship between Lp(a) and cardiovascular disease, especially in terms of prognosis. This study aimed at evaluating the predictive value of Lp(a) (cut-off 30 mg/dL) for hard events (HEs: mortality and non-fatal myocardial infarction) according to sex and cardiometabolic risk factors in 2110 patients (1501 males, mean age: 68 ± 9 years) undergoing coronary angiography for known or suspected coronary artery disease. There were 211 events over a median follow-up period of 33 months. Lp(a) > 30 mg/dL did not confer a worse prognosis on the overall population. However, Kaplan-Meier subgroup analysis evidenced a worse prognosis in type 2 diabetes (T2D) females with elevated Lp(a) (log-rank test: p = 0.03) vs. T2D males and no-T2D patients, but not in other high-risk cardiovascular states (e.g., smoking, hypertension, reduced left ventricular ejection fraction or obesity). After Cox multivariate adjustment, Lp(a) remained an independent determinant for HEs in the T2D female subgroup, conferring an HR of 2.9 (95% CI 1.1-7.7, p < 0.05). Lp(a) is therefore a strong independent predictor of HR in T2D women, but not in T2D men, or in noT2D patients.

Predictive effect of different blood lipid parameters combined with carotid intima-media thickness on coronary artery disease

Background

Blood lipids disorder and atherosclerosis are closely related to coronary artery disease (CAD). This study aims to compare different blood lipid parameters combined with carotid intima-media thickness (cIMT) in predicting CAD.

Methods

This was a retrospective study including patients who underwent coronary angiography for highly suspected CAD. Blood samples were taken for lipid profile analysis and cIMT was evaluated by carotid ultrasound. Logistic analysis was used to establish different models of different lipid parameters in predicting CAD. The area under the receiver operating characteristic curve (AUC) was used to examine the predictive value. The optimal lipid parameter was also used to explore the relationship with multi-vessel CAD.

Results

Patients were classified into two groups based on whether CAD existed. Compared with non-CAD patients, the CAD group had higher lipoprotein (a) [Lp (a)], apolipoprotein B/apolipoprotein A, total cholesterol/high-density lipoprotein cholesterol (HDL-C), triglyceride/HDL-C and LDL-C/HDL-C. According to the AUCs, Lp (a) combined with cIMT (AUC: 0.713, P < 0.001) had the best performance in predicting CAD compared to other lipid parameters. High level of Lp (a) was also associated with multi-vessel CAD (odds ratio: 1.41, 95% confidence interval: 1.02-1.95, P = 0.036).

Conclusion

For patients with highly suspected CAD, Lp (a) better improved the predictive value of CAD rather than most of blood lipid indices, especially in the absence of high levels of LDL-C. Lp (a) also can be used to predict the multi-vessel CAD.

Cardiovascular risk-enhancing factors and coronary artery calcium in South Asian American adults: The MASALA study

Objectives

The 2018 and 2019 U.S. guidelines for the management of cholesterol and primary prevention of atherosclerotic cardiovascular disease (ASCVD) recommend consideration of cardiovascular risk-enhancing factors (REFs), including South Asian ancestry, to refine ASCVD risk estimation. However, the associations of REFs with atherosclerosis are unclear in South Asian American adults, who have a disproportionately elevated premature coronary heart disease risk. In the Mediators of Atherosclerosis in South Asians Living in America (MASALA) cohort, we investigated associations of individual REFs, or the number of REFs, with coronary artery calcium (CAC).

Methods

Using baseline and follow-up data from MASALA, we evaluated the association of REFs (family history of ASCVD, low-density lipoprotein cholesterol ≥160 mg/dL, triglycerides ≥175 mg/dL, lipoprotein(a) >50 mg/dL, high-sensitivity C-reactive protein [hsCRP] ≥2.0 mg/dL, ankle-brachial index <0.9, chronic kidney disease, metabolic syndrome), individually and combined, with baseline prevalent CAC, any CAC progression (including incident CAC and CAC progression), and annual CAC progression rates using multivariable logistic regression and generalized linear models.

Results

Among 866 adults, mean age was 55 [SD 9] years and 47% were female. There were no significant associations of REFs with baseline prevalent CAC or any CAC progression (incident CAC and CAC progression at Exam 2) after adjustment. Among the 56% of participants who had any CAC progression, having 3+ REFs was associated with a significantly higher annual CAC progression rate (adjusted rate ratio [aRR] 1.94, 95% CI 1.39-2.72) vs. having 0 REFs. The annual CAC progression rate was 20% higher per additional REF (aRR 1.20, 95% CI 1.09-1.32). Findings were similar after excluding statin users, and among those with low 10-year ASCVD risk (<5%).

Conclusions

Among South Asian American adults, we found no association of REFs with prevalent CAC at baseline or having any CAC progression. Among those with any CAC progression, a higher number of REFs was associated with higher annual CAC progression rates.

Relationship of low-density lipoprotein-cholesterol and lipoprotein(a) to cardiovascular risk: The Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND AND AIMS

Plasma low-density lipoprotein cholesterol (LDL-C) and lipoprotein(a) (Lp(a)) are both associated with coronary heart disease (CHD). This study investigated whether elevated plasma Lp(a) concentration was associated with increased CHD risk when LDL-C was low (≤100 mg/dL) in individuals not on statin therapy.

METHODS

Participants from the Multi-Ethnic Study of Atherosclerosis (MESA) (n = 4,585) were categorized into four groups: Group 1: LDL-C ≤ 100 mg/dL, Lp(a) < 50 mg/dL; Group 2: LDL-C > 100 mg/dL, Lp(a) < 50 mg/dL; Group 3: LDL-C ≤ 100 mg/dL, Lp(a) ≥ 50 mg/dL; and Group 4: LDL-C > 100 mg/dL, Lp(a) ≥ 50 mg/dL. The relationship of Lp(a) and LDL-C with time to CHD events was assessed with Kaplan Meier curves and multivariable Cox proportional hazard models.

RESULTS

Participants were followed for a mean of 13.4 years and a total of 315 CHD events occurred. Compared to participants with LDL-C ≤ 100 mg/dL and Lp(a) < 50 mg/dL, those with LDL-C > 100 mg/dL and Lp(a) < 50 mg/dL (Group 2) demonstrated no increased risk for CHD events (HR: 0.92; 95% CI: 0.69, 1.21). However, participants with LDL-C ≤ 100 mg/dL and Lp(a) ≥ 50 mg/dL (Group 3) and those with LDL-C > 100 mg/dL and Lp(a) ≥ 50 mg/dL (Group 4) exhibited significantly increased risk of CHD events compared to Group 1 (HR: 1.83; 95% CI: 1.02, 3.27) and Group 2 (HR: 1.61; 95% CI: 1.15, 2.26), respectively.

CONCLUSIONS

When Lp(a) was elevated, risk of CHD events increased, regardless of baseline LDL-C.

Consensus and guidelines on lipoprotein(a) - seeing the forest through the trees

PURPOSE OF THE REVIEW

Over the past decade, lipoprotein(a) [Lp(a)] made it to several consensus and guideline documents. This review aims to summarize the literature which underlies the various recommendations and compares recent European and North American consensus and guideline documents of the recent 3-4 years.

RECENT FINDINGS

Multiple large epidemiological and genetic studies have provided strong evidence for a causal association between Lp(a) concentrations and atherosclerotic cardiovascular disease (ASCVD) and aortic valve stenosis. There is a dose-dependent linear relationship between Lp(a) and ASCVD risk advocating to consider Lp(a) on a continuous scale rather than using thresholds. The best way to implement this in the clinic is by individualizing the Lp(a)-related risk using tools such as the 'Lp(a) risk calculator' ( http://www.lpaclinicalguidance.com ) that takes into account the Lp(a) level in the context of an individual's traditional risk factors and global risk for ASCVD. There is growing agreement across the guidelines regarding the clinical utility of measuring Lp(a) and more recent expert groups advocate for a general screening approach applied to all adults. As long as the cardiovascular outcomes trials for specific Lp(a)-lowering drugs are in progress, the current management of patients with high Lp(a) should focus on the comprehensive management of all other modifiable ASCVD risk factors which can be therapeutically addressed as per guideline recommendations.

SUMMARY

Since the contribution of high Lp(a) concentrations to global ASCVD risk has been underestimated in the past, a clear recommendation to measure Lp(a) at least once in a person's lifetime is imperative. Recent expert consensus recommendations provide clinicians with direction on how to manage the excess risk associated with elevated Lp(a) concentration by comprehensive and individualized management of modifiable ASCVD risk factors while awaiting the results of clinical trials of Lp(a) targeted therapies.

The kringle IV type 2 domain variant 4925G>A causes the elusive association signal of the LPA pentanucleotide repeat

Lipoprotein(a) [Lp(a)] concentrations are regulated by the LPA gene mainly via the large kringle IV-type 2 (KIV-2) copy number variation and multiple causal variants. Early studies suggested an effect of long pentanucleotide repeat (PNR) alleles (10 and 11 repeats, PNR10 and PNR11) in the LPA promoter on gene transcription and found an association with lower Lp(a). Subsequent in vitro studies showed no effects on mRNA transcription, but the association with strongly decreased Lp(a) remained consistent. We investigated the isolated and combined effect of PNR10, PNR11, and the frequent splice site variant KIV-2 4925G>A on Lp(a) concentrations in the Cooperative Health Research in the Region of Augsburg F4 study by multiple quantile regression in single-SNP and joint models. Data on Lp(a), apolipoprotein(a) Western blot isoforms, and variant genotypes were available for 2,858 individuals. We found a considerable linkage disequilibrium between KIV-2 4925G>A and the alleles PNR10 and PNR11. In single-variant analysis adjusted for age, sex, and the shorter apo(a) isoform, we determined that both PNR alleles were associated with a highly significant Lp(a) decrease (PNR10: β = -14.43 mg/dl, 95% CI: -15.84, -13.02, P = 3.33e-84; PNR11: β = -17.21 mg/dl, 95% CI: -20.19, -14.23, P = 4.01e-29). However, a joint model, adjusting the PNR alleles additionally for 4925G>A, abolished the effect on Lp(a) (PNR10: β = +0.44 mg/dl, 95% CI: -1.73, 2.60, P = 0.69; PNR11: β = -1.52 mg/dl, 95% CI: -6.05, 3.00, P = 0.51). Collectively, we conclude that the previously reported Lp(a) decrease observed in pentanucleotide alleles PNR10 or PNR11 carriers results from a linkage disequilibrium with the frequent splicing mutation KIV-2 4925G>A.

Non-genetic influences on lipoprotein(a) concentrations

An elevated level of lipoprotein(a) [Lp(a)] is a genetically regulated, independent, causal risk factor for cardiovascular disease. However, the extensive variability in Lp(a) levels between individuals and population groups cannot be fully explained by genetic factors, emphasizing a potential role for non-genetic factors. In this review, we provide an overview of current evidence on non-genetic factors influencing Lp(a) levels with a particular focus on diet, physical activity, hormones and certain pathological conditions. Findings from randomized controlled clinical trials show that diets lower in saturated fats modestly influence Lp(a) levels and often in the opposing direction to LDL cholesterol. Results from studies on physical activity/exercise have been inconsistent, ranging from no to minimal or moderate change in Lp(a) levels, potentially modulated by age and the type, intensity, and duration of exercise modality. Hormone replacement therapy (HRT) in postmenopausal women lowers Lp(a) levels with oral being more effective than transdermal estradiol; the type of HRT, dose of estrogen and addition of progestogen do not modify the Lp(a)-lowering effect of HRT. Kidney diseases result in marked elevations in Lp(a) levels, albeit dependent on disease stages, dialysis modalities and apolipoprotein(a) phenotypes. In contrast, Lp(a) levels are reduced in liver diseases in parallel with the disease progression, although population studies have yielded conflicting results on the associations between Lp(a) levels and nonalcoholic fatty liver disease. Overall, current evidence supports a role for diet, hormones and related conditions, and liver and kidney diseases in modifying Lp(a) levels.

Lipoprotein(a) measurement issues: Are we making a mountain out of a molehill?

Lipoprotein(a) [Lp(a)] became besides LDL cholesterol one of the most attractive targets for intervention in cardiovascular disease. Strong genetic evidence supports the causal association between high Lp(a) concentrations and cardiovascular outcomes. Since specific Lp(a)-lowering therapies are under clinical investigation, the interest in measuring Lp(a) has markedly increased. However, the special structure of the lead protein component of Lp(a), named apolipoprotein(a), creates difficulties for an accurate measurement of Lp(a). A highly homologous repetitive structure, called kringle IV repeat with up to more the 40 repeats, causes a highly polymorphic protein. Antibodies raised against apolipoprotein(a) are mostly directed against the repetitive structure of this protein, which complicates the measurement of Lp(a) in molar terms. Both measurements in mass (mg/dL) and molar terms (nmol/L) are described and a conversion from one into the another unit is only approximately possible. Working groups for standardization of Lp(a) measurements are going to prepare widely available and improved reference materials, which will be a major step for the measurement of Lp(a). This review discusses many aspects of the difficulties in measuring Lp(a). It tries to distinguish between academic and practical concerns and warns to make a mountain out of a molehill, which does no longer allow to see the patient behind that mountain by simply staring at the laboratory issues. On the other hand, the calibration of some assays raises major concerns, which are anything else but a molehill. This should be kept in mind and we should start measuring Lp(a) with the aim of a better risk stratification for the patient and to identify those patients who might be in urgent need for a specific Lp(a)-lowering therapy as soon as it becomes available.