The role of Lipoprotein(a) in cardiovascular disease: Current concepts and future perspectives

Closing the gap: Solving complex medically relevant genes at scale

Comprehending the mechanism behind human diseases with an established heritable component represents the forefront of personalized medicine. Nevertheless, numerous medically important genes are inaccurately represented in short-read sequencing data analysis due to their complexity and repetitiveness or the so-called 'dark regions' of the human genome. The advent of PacBio as a long-read platform has provided new insights, yet HiFi whole-genome sequencing (WGS) cost remains frequently prohibitive. We introduce a targeted sequencing and analysis framework, Twist Alliance Dark Genes Panel (TADGP), designed to offer phased variants across 389 medically important yet complex autosomal genes. We highlight TADGP accuracy across eleven control samples and compare it to WGS. This demonstrates that TADGP achieves variant calling accuracy comparable to HiFi-WGS data, but at a fraction of the cost. Thus, enabling scalability and broad applicability for studying rare diseases or complementing previously sequenced samples to gain insights into these complex genes. TADGP revealed several candidate variants across all cases and provided insight into LPA diversity when tested on samples from rare disease and cardiovascular disease cohorts. In both cohorts, we identified novel variants affecting individual disease-associated genes (e.g., IKZF1, KCNE1). Nevertheless, the annotation of the variants across these 389 medically important genes remains challenging due to their underrepresentation in ClinVar and gnomAD. Consequently, we also offer an annotation resource to enhance the evaluation and prioritization of these variants. Overall, we can demonstrate that TADGP offers a cost-efficient and scalable approach to routinely assess the dark regions of the human genome with clinical relevance.

Confounding Factors Responsible for Elevated Lp(a) Levels in Patients with Coronary Artery Disease

BACKGROUND

Cardiovascular diseases (CVDs) are a leading cause of global mortality, motivating research into novel approaches for their management. Lipoprotein(a) (Lp(a)), a unique lipoprotein particle, has been implicated in atherosclerosis and thrombosis, suggesting its potential as a therapeutic target for CVDs.

AIM

This study aimed to investigate the association of Lp(a) levels with various cardiovascular parameters and events among patients with confirmed cardiovascular disease.

METHODOLOGY

A prospective study was conducted, enrolling 600 participants, predominantly comprising males (79%), with a mean age of 52.78 ± 0.412 years diagnosed with cardiovascular disease. The follow-up was done for 18 months. Patient demographics, blood investigations, and occurrence of major adverse cardiac events (MACE) were collected. SPSS version 21 was used to statistically analyze the relationships between elevated Lp(a) levels and factors such as age, glycated hemoglobin, mortality, MACE, cardiac death, target vessel revascularization, and stroke.

RESULTS

The study revealed significant (P < 0.05) associations between elevated Lp(a) levels and advanced age, increased glycated hemoglobin levels, as well as occurrences of all-cause mortality, MACE, cardiac death, target vessel revascularization, and stroke. Notably, a significant (P < 0.05), association between high Lp(a) levels and acute coronary syndrome (ACS) emerged, suggesting Lp(a)'s role in advanced cardiac events.

CONCLUSION

The findings highlight the potential significance of Lp(a) as a notable risk factor in cardiovascular health. The observed associations between elevated Lp(a) and adverse cardiovascular events, including ACS, underscore its pathogenic role. Consequently, this study supports the rationale for further research into Lp(a)-specific therapeutic interventions, offering substantial promise in refining the management strategies for cardiovascular diseases.

Lp(a) and risk of cardiovascular disease - A review of existing evidence and emerging concepts

Cardiovascular disease (CVD) remains the leading cause of death among adults in the United States. There has been significant advancement in the diagnosis and treatment of atherosclerotic cardiovascular disease (ASCVD) and its underlying risk factors. In certain populations, there remains a significant residual risk despite adequate lowering of low-density lipoprotein cholesterol (LDL-C) and control of traditional risk factors. This has led to an interest in research to identify additional risk factors that contribute to atherosclerotic cardiovascular disease. Elevated lipoprotein (a) [Lp(a)] has been identified as an independent risk factor contributing to an increased risk for CVD. There are also ethnic and racial disparities in Lp(a) inheritance that need to be understood. This paper reviews the current literature on lipoprotein a, proposed mechanisms of actions for cardiovascular disease, recommendations for testing, and the current and emerging therapies for lowering Lp(a).

Lipoprotein(a)-60 Years Later-What Do We Know?

Lipoprotein(a) (Lp(a)) molecule includes two protein components: apolipoprotein(a) and apoB100. The molecule is the main transporter of oxidized phospholipids (OxPL) in plasma. The concentration of this strongly atherogenic lipoprotein is predominantly regulated by the LPA gene expression. Lp(a) is regarded as a risk factor for several cardiovascular diseases. Numerous epidemiological, clinical and in vitro studies showed a strong association between increased Lp(a) and atherosclerotic cardiovascular disease (ASCVD), calcific aortic valve disease/aortic stenosis (CAVD/AS), stroke, heart failure or peripheral arterial disease (PAD). Although there are acknowledged contributions of Lp(a) to the mentioned diseases, clinicians struggle with many inconveniences such as a lack of well-established treatment lowering Lp(a), and common guidelines for diagnosing or assessing cardiovascular risk among both adult and pediatric patients. Lp(a) levels are different with regard to a particular race or ethnicity and might fluctuate during childhood. Furthermore, the lack of standardization of assays is an additional impediment. The review presents the recent knowledge on Lp(a) based on clinical and scientific research, but also highlights relevant aspects of future study directions that would approach more suitable and effective managing risk associated with increased Lp(a), as well as control the Lp(a) levels.

Hyperlipoproteinemia (a) and Phytoestrogen Therapy in Dialysis Patients: A Review

PURPOSE

Hyperlipoproteinemia (a) is a prevalent complication in dialysis patients, with no valid treatment strategy. The aim of this narrative review was to investigate the clinical significance of hyperlipoproteinemia (a) and phytoestrogen therapy in dialysis patients.

METHODS

A comprehensive literature search of the published data was performed regarding the effects of phytoestrogen therapy on hyperlipoproteinemia (a) in dialysis patients.

FINDINGS

Hyperlipoproteinemia (a) occurs in dialysis patients due to decreased catabolism and increased synthesis of lipoprotein (a) [Lp(a)]. A few clinical trials have studied the effects of phytoestrogens on serum Lp(a). All studies of dialysis patients or nonuremic individuals with hyperlipoproteinemia (a), except one, showed that phytoestrogens could significantly reduce serum Lp(a) levels. However, all investigations of phytoestrogen therapy in individuals with normal serum Lp(a) levels showed that it had no effect on serum Lp(a). Phytoestrogens seem to have effects similar to those of estrogen in lowering Lp(a) concentrations.

IMPLICATIONS

Considering the high prevalence of hyperlipoproteinemia (a) in dialysis patients, phytoestrogen therapy is a reasonable approach for reducing serum Lp(a) levels and its complications in these patients.

Current Management and Future Perspectives in the Treatment of Lp(a) with a Focus on the Prevention of Cardiovascular Diseases

Lipoprotein(a) [Lp(a)] is a lipid molecule with atherogenic, inflammatory, thrombotic, and antifibrinolytic effects, whose concentrations are predominantly genetically determined. The association between Lp(a) and cardiovascular diseases (CVDs) has been well-established in numerous studies, and the ability to measure Lp(a) levels is widely available in the community. As such, there has been increasing interest in Lp(a) as a therapeutic target for the prevention of CVD. The impact of the currently available lipid-modifying agents on Lp(a) is modest and heterogeneous, except for the monoclonal antibody proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i), which demonstrated a significant reduction in Lp(a) levels. However, the absolute reduction in Lp(a) to significantly decrease CVD outcomes has not been definitely established, and the magnitude of the effect of PCSK9i seems insufficient to directly reduce the Lp(a)-related CVD risk. Therefore, emerging therapies are being developed that specifically aim to lower Lp(a) levels and the risk of CVD, including RNA interference (RNAi) agents, which have the capacity for temporary and reversible downregulation of gene expression. This review article aims to summarize the effects of Lp(a) on CVD and to evaluate the available evidence on established and emerging therapies targeting Lp(a) levels, focusing on the potential reduction of CVD risk attributable to Lp(a) concentrations.

VLDL receptor gene therapy for reducing atherogenic lipoproteins

Over the past 40 years, there has been considerable research into the management and treatment of atherogenic lipid disorders. Although the majority of treatments and management strategies for cardiovascular disease (CVD) center around targeting low-density lipoprotein cholesterol (LDL-C), there is mounting evidence for the residual CVD risk attributed to high triglyceride (TG) and lipoprotein(a) (Lp(a)) levels despite the presence of lowered LDL-C levels. Among the biological mechanisms for clearing TG-rich lipoproteins, the VLDL receptor (VLDLR) plays a key role in the trafficking and metabolism of lipoprotein particles in multiple tissues, but it is not ordinarily expressed in the liver. Since VLDLR is capable of binding and internalizing apoE-containing TG-rich lipoproteins as well as Lp(a), hepatic VLDLR expression has the potential for promoting clearance of these atherogenic particles from the circulation and managing the residual CVD risk not addressed by current lipid lowering therapies. This review provides an overview of VLDLR function and the potential for developing a genetic medicine based on liver-targeted VLDLR gene expression.

Residual Atherosclerotic Cardiovascular Disease Risk: Focus on Non-High-Density Lipoprotein Cholesterol

Cardiovascular disease (CVD) caused by atherosclerosis is the leading cause of death worldwide. The level of low-density lipoprotein cholesterol (LDL-C), considered as the initiator of atherosclerosis, is the most widely used predictor for CVD risk and LDL-C has been the primary target for lipid-lowering therapies. However, residual CVD risk remains high even with very low levels of LDL-C. This residual CVD risk may be due to remnant cholesterol, high triglyceride levels, and low high-density lipoprotein cholesterol (HDL-C). Non-high density lipoprotein cholesterol (non-HDL-C), which is calculated as total cholesterol minus HDL-C (and represents the cholesterol content of all atherogenic apolipoprotein B-containing lipoproteins), has emerged as a better risk predictor for CVD than LDL-C and an alternative target for CVD risk reduction. Major international guidelines recommend evaluating non-HDL-C as part of atherosclerotic CVD risk assessment, especially in people with high triglycerides, diabetes, obesity, or very low LDL-C. A non-HDL-C target of <130 mg/dL (3.4 mmol/L) has been recommended for patients at very high risk, which is 30 mg/dL (0.8 mmol/L) higher than the corresponding LDL-C target goal. Non-HDL-C lowering approaches include reducing LDL-C and triglyceride levels, increasing HDL-C, or targeting multiple risk factors simultaneously. However, despite the growing evidence for the role of non-HDL-C in residual CVD risk, and recommendations for its assessment in major guidelines, non-HDL-C testing is not routinely done in clinical practice. Thus, there is a need for increased awareness of the need for non-HDL-C testing for ascertaining CVD risk and concomitant prevention of CVD.

Lipoprotein(a) and residual vascular risk in statin-treated patients with first acute ischemic stroke: A prospective cohort study

OBJECTIVES

Statins either barely affect or increase lipoprotein(a) [Lp(a)] levels. This study aimed to explore the factors correlated to the change of Lp(a) levels as well as the relationship between Lp(a) and the recurrent vascular events in statin-treated patients with first acute ischemic stroke (AIS).

METHODS

Patients who were admitted to the hospital with first AIS from October 2018 to September 2020 were eligible for inclusion. Correlation between the change of Lp(a) levels and potential influencing factors was assessed by linear regression analysis. Cox proportional regression models were used to estimate the association between Lp(a) and recurrent vascular events including AIS, transient ischemic attack, myocardial infarction and coronary revascularization.

RESULTS

In total, 303 patients, 69.6% males with mean age 64.26 ± 11.38 years, completed the follow-up. During the follow-up period, Lp(a) levels increased in 50.5% of statin-treated patients and the mean percent change of Lp(a) levels were 14.48% (95% CI 6.35-22.61%). Creatinine (β = 0.152, 95% CI 0.125-0.791, P = 0.007) and aspartate aminotransferase (AST) (β = 0.160, 95% CI 0.175-0.949, P = 0.005) were positively associated with the percent change of Lp(a) levels. During a median follow-up of 26 months, 66 (21.8%) patients had a recurrent vascular event. The median time period between AIS onset and vascular events recurrence was 9.5 months (IQR 2.0-16.3 months). The on-statin Lp(a) level ≥70 mg/dL (HR 2.539, 95% CI 1.076-5.990, P = 0.033) and the change of Lp(a) levels (HR 1.003, 95% CI 1.000-1.005, P = 0.033) were associated with the recurrent vascular events in statin-treated patients with first AIS. Furthermore, the on-statin Lp(a) levels ≥70 mg/dL (HR 3.612, 95% CI 1.018-12.815, P = 0.047) increased the risk of recurrent vascular events in patients with low-density lipoprotein cholesterol (LDL-C) levels < 1.8 mmol/L.

CONCLUSIONS

Lp(a) levels increased in half of statin-treated patients with first AIS. Creatinine and AST were positively associated with the percent change of Lp(a) levels. Lp(a) is a determinant of residual vascular risk and the change of Lp(a) is positively associated with the risk of recurrent vascular events in these patients.

Effect of lipoprotein (a) on the analytical determination of low-density lipoprotein cholesterol (LDLc) and its influence on pharmacological treatment with atorvastatin

Lipoprotein(a) (Lp(a)) and Low-density lipoprotein cholesterol (LDLc) is an important risk factor for atherosclerotic cardiovascular disease. The objective of this study was to determine the impact of Lp(a) concentration both on the indirect analytical measurement of LDLc and on the efficacy of dyslipidaemia treatment using the atorvastatin statin. Two retrospective studies were conducted, one with 340 patients and another with 107 patients treated with atorvastatin. Lp(a) concentrations were measured by turbidimetry with an assay independent of the size of the apo(a) isoform. LDLc was calculated using the Friedewald equation and the corrected LDLc was calculated using the Dahlén equation. A strong positive correlation was observed between the serum Lp(a) concentration and the LDLc-overestimation percentage (r = 0.960, p < .001). It was also observed that as the Lp(a) concentration rose there was no significant variation in the percentage decrease in corrected LDLc during atorvastatin treatment (r = 0.186, p > .05). The concentration of LDLc obtained by using the Friedewald equation included Lp(a) cholesterol. The lowering of LDLc in patients treated with atorvastatin depended solely on accessible LDL cholesterol and not on Lp(a) cholesterol.

Elevated lipoprotein(a) levels as an independent predictor of long-term recurrent events in patients with acute coronary syndrome: an observational, retrospective cohort study

BACKGROUND

Whether lipoprotein(a) [Lp(a)] is associated with recurrent cardiovascular events (RCVEs) still remains controversial. The present study aimed to investigate the prognostic value of Lp(a) for long-term RCVEs and each component of it in people with acute coronary syndrome (ACS).

METHODS

This multicenter, observational and retrospective study enrolled 765 ACS patients at 11 hospitals in Chengdu from January 2014 to June 2019. Patients were assigned to low-Lp(a) group [Lp(a) < 30 mg/dl] and high-Lp(a) group [Lp(a) ≥ 30 mg/dl]. The primary and secondary endpoints were defined as RCVEs and their elements, including all-cause death, nonfatal myocardial infarction (MI), nonfatal stroke and unplanned revascularization.

RESULTS

Over a median 17-month follow-up, 113 (14.8%) patients presented with RCVEs were reported, among which we observed 57 (7.5%) all-cause deaths, 22 (2.9%) cases of nonfatal stroke, 13 (1.7%) cases of nonfatal MI and 33 (4.3%) cases of unplanned revascularization. The incidences of RCVEs and revascularization in the high-Lp(a) group were significantly higher than those in the low-Lp(a) group ( P < 0.05), whereas rates of all-cause death, nonfatal stroke and nonfatal MI were not statistically different ( P > 0.05). Kaplan-Meier analysis also revealed the same trend. Multivariate Cox proportional hazards analysis showed that 1-SD increase of Lp(a) was independently associated with both the primary endpoint event [hazard ratio (HR), 1.285 per 1-SD; 95% confidence interval (CI), 1.112-1.484; P < 0.001] and revascularization (HR, 1.588 per 1-SD; 95% CI, 1.305-1.932; P < 0.001), but not with the other secondary events.

CONCLUSION

Increased Lp(a) is an independent predictor of RCVEs and unplanned revascularization in patients with ACS.

Lipoprotein(a): Insights for the Practicing Clinician

Following the discovery of the Lipoprotein(a) (Lp(a)) molecule by Kare Berg in 1963, many physiological and pathological properties of this particle remain to be fully understood. Multiple population-based studies have demonstrated a correlation between elevated Lp(a) levels and the incidence of cardiovascular disease. Data extrapolated from the Copenhagen City Heart and ASTRONOMER studies also demonstrated the link between Lp(a) levels and the incidence and rate of progression of calcific aortic stenosis. Interest in Lp(a) has increased in recent years, partly due to new emerging therapies that can specifically reduce serum Lp(a) concentrations. Given the strong correlation between Lp(a) and CV disease from epidemiological studies, several international guidelines have also been updated to advocate Lp(a) testing in specific population groups. This review aims to highlight the importance of the role of Lp(a) in cardiovascular disease and discusses the potential of novel therapies in patients with elevated Lp(a) levels.

Polymorphisms of LPA gene, rs1801693 and rs7765781, are not associated with premature myocardial infarction in the Iranian population

BACKGROUND

Myocardial infarction (MI) is one of the leading causes of mortality globally. Although it is most prevalent in the elderly, it may occur in young adults (men ≤ 55 years or women ≤ 65 years) as premature MI (PMI). As awareness of genetic risks may lead to effective prevention of PMI, we aim to investigate the association of two susceptible single nucleotide polymorphisms (SNPs) in the LPA gene with PMI in the Iranian population, rs1801693 and rs7765781, identified in previous genome-wide association studies (GWAS).

METHODS

A total number of 85 patients with PMI and 85 healthy controls were recruited from December 2015 to March 2016 from Isfahan, Iran. Peripheral blood samples were collected from all individuals. Deoxyribonucleic acid (DNA) was extracted and genotyped at rs1181693 and rs7765781 polymorphisms, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Results were statistically analyzed to find any possible association of the two polymorphisms with PMI by SPSS software and P-values less than 0.05 were considered to be statistically significant.

RESULTS

Statistical analysis displayed no significant difference between rs1801693 (P = 0.815)/rs7765781 (P = 0.746) alleles in patients with PMI and healthy control subjects.

CONCLUSION

There is no meaningful association between rs1801693/rs7765781 and PMI incidence in the Iranian population.