The 10 essential questions regarding lipoprotein(a).

PURPOSE OF REVIEW: Lp(a) is one of the most atherogenic lipoproteins, and significant progress has been made to understand its pathophysiology over the last 20 years. There are now selective therapies in late-stage clinical trials to lower Lp(a). Yet there are many outstanding questions about Lp(a). This review outlines 10 of the most burning questions and tries to answer some of them. RECENT FINDINGS: Antisense oligonucleotide (ASO) treatment is currently the most advanced therapy to lower plasma Lp(a) by 60-80%. There are, however, also two small molecule medications in early stage of development with similar efficacy. SUMMARY: This review aims to answer important preclinical and clinical questions about the metabolism and physiological role of Lp(a) and also outlines possible therapeutic approaches with nutraceuticals, currently available lipid-lowering therapies and new medications. In addition, ways are illustrated to use Lp(a) as a marker to better predict cardiovascular risk.

Australian Atherosclerosis Society Position Statement on Lipoprotein(a): Clinical and Implementation Recommendations.

This position statement provides guidance to cardiologists and related specialists on the management of adult patients with elevated lipoprotein(a) [Lp(a)]. Elevated Lp(a) is an independent and causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and calcific aortic valve disease (CAVD). While circulating Lp(a) levels are largely determined by ancestry, they are also influenced by ethnicity, hormones, renal function, and acute inflammatory events, such that measurement should be done after accounting for these factors. Further, circulating Lp(a) concentrations should be estimated using an apo(a)-isoform independent assay that employs appropriate calibrators and reports the results in molar units (nmol/L). Selective screening strategies of high-risk patients are recommended, but universal screening of the population is currently not advised. Testing for elevated Lp(a) is recommended in all patients with premature ASCVD and those considered to be at intermediate-to-high risk of ASCVD. Elevated Lp(a) should be employed to assess and stratify risk and to enable a decision on initiation or intensification of preventative treatments, such as cholesterol lowering therapy. In adult patients with elevated Lp(a) at intermediate-to-high risk of ASCVD, absolute risk should be reduced by addressing all modifiable behavioural, lifestyle, psychosocial and clinical risk factors, including maximising cholesterol-lowering with statin and ezetimibe and, where appropriate, PCSK9 inhibitors. Apheresis should be considered in patients with progressive ASCVD. New ribonucleic acid (RNA)-based therapies which directly lower Lp(a) are undergoing clinical trials.

Lp(a) and the Risk for Cardiovascular Disease: Focus on the Lp(a) Paradox in Diabetes Mellitus.

Lipoprotein(a) (Lp(a)) is one of the strongest causal risk factors of atherosclerotic disease. It is rich in cholesteryl ester and composed of apolipoprotein B and apo(a). Plasma Lp(a) levels are determined by apo(a) transcriptional activity driven by a direct repeat (DR) response element in the apo(a) promoter under the control of (HNF)4α Farnesoid-X receptor (FXR) ligands play a key role in the downregulation of APOA expression. In vitro studies on the catabolism of Lp(a) have revealed that Lp(a) binds to several specific lipoprotein receptors; however, their in vivo role remains elusive. There are more than 1000 publications on the role of diabetes mellitus (DM) in Lp(a) metabolism; however, the data is often inconsistent and confusing. In patients suffering from Type-I diabetes mellitus (T1DM), provided they are metabolically well-controlled, Lp(a) plasma concentrations are directly comparable to healthy individuals. In contrast, there exists a paradox in T2DM patients, as many of these patients have reduced Lp(a) levels; however, they are still at an increased cardiovascular risk. The Lp(a) lowering mechanism observed in T2DM patients is most probably caused by mutations in the mature-onset diabetes of the young (MODY) gene and possibly other polymorphisms in key transcription factors of the apolipoprotein (a) gene (APOA).

Essentials of a new clinical practice guidance on familial hypercholesterolaemia for physicians.

Familial hypercholesterolaemia (FH) is a common, heritable and preventable cause of premature coronary artery disease. New clinical practice recommendations are presented to assist practitioners in enhancing the care of all patients with FH. Core recommendations are made on the detection, diagnosis, assessment and management of adults, children and adolescents with FH. Management is under-pinned by the precepts of risk stratification, adherence to healthy lifestyles, treatment of non-cholesterol risk factors and appropriate use of low-density lipoprotein (LDL)-cholesterol-lowering therapies including statins, ezetimibe and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors. The recommendations need to be utilised using judicious clinical judgement and shared decision-making with patients and families. New government-funded schemes for genetic testing and use of PCSK9 inhibitors, as well as the National Health Genomics Policy Framework, will enable adoption of the recommendations. However, a comprehensive implementation science and practice strategy is required to ensure that the guidance translates into benefit for all families with FH.

Integrated Guidance for Enhancing the Care of Familial Hypercholesterolaemia in Australia.

Familial hypercholesterolaemia (FH) is a dominant and highly penetrant monogenic disorder present from birth that markedly elevates plasma low-density lipoprotein (LDL)-cholesterol concentration and, if untreated, leads to premature atherosclerosis and coronary artery disease (CAD). There are approximately 100,000 people with FH in Australia. However, an overwhelming majority of those affected remain undetected and inadequately treated, consistent with FH being a leading challenge for public health genomics. To further address the unmet need, we provide an updated guidance, presented as a series of systematically collated recommendations, on the care of patients and families with FH. These recommendations have been informed by an exponential growth in published works and new evidence over the last 5 years and are compatible with a contemporary global call to action on FH. Recommendations are given on the detection, diagnosis, assessment and management of FH in adults and children. Recommendations are also made on genetic testing and risk notification of biological relatives who should undergo cascade testing for FH. Guidance on management is based on the concepts of risk re-stratification, adherence to heart healthy lifestyles, treatment of non-cholesterol risk factors, and safe and appropriate use of LDL-cholesterol lowering therapies, including statins, ezetimibe, proprotein convertase subtilisin/kexin type 9 inhibitors and lipoprotein apheresis. Broad recommendations are also provided for the organisation and development of health care services. Recommendations on best practice need to be underpinned by good clinical judgment and shared decision making with patients and families. Models of care for FH need to be adapted to local and regional health care needs and available resources. A comprehensive and realistic implementation strategy, informed by further research, including assessments of cost-benefit, will be required to ensure that this new guidance benefits all Australian families with or at risk of FH.

Gaps in the Care of Familial Hypercholesterolaemia in Australia: First Report From the National Registry.

BACKGROUND: Familial hypercholesterolaemia (FH) is under-diagnosed and under-treated worldwide, including Australia. National registries play a key role in identifying patients with FH, understanding gaps in care and advancing the science of FH to improve care for these patients. METHODS: The FH Australasia Network has established a national web-based registry to raise awareness of the condition, facilitate service planning and inform best practice and care services in Australia. We conducted a cross-sectional analysis of 1,528 FH adults enrolled in the registry from 28 lipid clinics. RESULTS: The mean age at enrolment was 53.4±15.1 years, 50.5% were male and 54.3% had undergone FH genetic testing, of which 61.8% had a pathogenic FH-causing gene variant. Only 14.0% of the cohort were family members identified through cascade testing. Coronary artery disease (CAD) was reported in 28.0% of patients (age of onset 49.0±10.5 years) and 64.9% had at least one modifiable cardiovascular risk factor. The mean untreated LDL-cholesterol was 7.4±2.5 mmol/L. 80.8% of patients were on lipid-lowering therapy with a mean treated LDL-cholesterol of 3.3±1.7 mmol/L. Among patients receiving lipid-lowering therapies, 25.6% achieved an LDL-cholesterol target of <2.5 mmol/L without CAD or <1.8 mmol/L with CAD. CONCLUSION: Patients in the national FH registry are detected later in life, have a high burden of CAD and risk factors, and do not achieve guideline-recommended LDL-cholesterol targets. Genetic and cascade testing are under-utilised. These deficiencies in care need to be addressed as a public health priority.

Familial Hypercholesterolaemia in 2020: A Leading Tier 1 Genomic Application.

Familial hypercholesterolaemia (FH) is caused by a major genetic defect in the low-density lipoprotein (LDL) clearance pathway. Characterised by LDL-cholesterol elevation from birth, FH confers a significant risk for premature coronary artery disease (CAD) if overlooked and untreated. With risk exposure beginning at birth, early detection and intervention is crucial for the prevention of CAD. Lowering LDL-cholesterol with lifestyle and statin therapy can reduce the risk of CAD. However, most individuals with FH will not reach guideline recommended LDL-cholesterol targets. FH has an estimated prevalence of approximately 1:250 in the community. Multiple strategies are required for screening, diagnosing and treating FH. Recent publications on FH provide new data for developing models of care, including new therapies. This review provides an overview of FH and outlines some recent advances in the care of FH for the prevention of CAD in affected families. The future care of FH in Australia should be developed within the context of the National Health Genomics Policy Framework.

Status of PCSK9 Monoclonal Antibodies in Australia.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) monoclonal antibodies (mAb) have progressed from showing marked low density lipoprotein cholesterol lowering in early phase trials through to reducing cardiovascular events in large clinical outcome trials. Recently in Australia, the indication for evolocumab has been expanded to include both heterozygous and homozygous familial hypercholesterolaemia under the Pharmaceutical Benefits Scheme (PBS). With prices remaining high currently their use in non-familial hypercholesterolaemia in Australia remains by private prescription only at this stage. This manuscript summarises the major outcomes trials of the PCSK9 mAbs and the secondary analyses that have assessed their benefits in high risk patient groups, and describes the consensus of authors on which patients would most likely benefit from PCSK9 mAb therapy.

Lipoprotein (a): a historical appraisal.

Initially, lipoprotein (a) [Lp(a)] was believed to be a genetic variant of lipoprotein (Lp)-B. Because its lipid moiety is almost identical to LDL, Lp(a) has been deliberately considered to be highly atherogenic. Lp(a) was detected in 1963 by Kare Berg, and individuals who were positive for this factor were called Lpa+ Lpa+ individuals were found more frequently in patients with coronary heart disease than in controls. After the introduction of quantitative methods for monitoring of Lp(a), it became apparent that Lp(a), in fact, is present in all individuals, yet to a greatly variable extent. The genetics of Lp(a) had been a mystery for a long time until Gerd Utermann discovered that apo(a) is expressed by a variety of alleles, giving rise to a unique size heterogeneity. This size heterogeneity, as well as countless mutations, is responsible for the great variability in plasma Lp(a) concentrations. Initially, we proposed to evaluate the risk of myocardial infarction at a cut-off for Lp(a) of 30-50 mg/dl, a value that still is adopted in numerous epidemiological studies. Due to new therapies that lower Lp(a) levels, there is renewed interest and still rising research activity in Lp(a). Despite all these activities, numerous gaps exist in our knowledge, especially as far as the function and metabolism of this fascinating Lp are concerned.

When should we measure lipoprotein (a)?

Recently published epidemiological and genetic studies strongly suggest a causal relationship of elevated concentrations of lipoprotein (a) [Lp(a)] with cardiovascular disease (CVD), independent of low-density lipoproteins (LDLs), reduced high density lipoproteins (HDL), and other traditional CVD risk factors. The atherogenicity of Lp(a) at a molecular and cellular level is caused by interference with the fibrinolytic system, the affinity to secretory phospholipase A2, the interaction with extracellular matrix glycoproteins, and the binding to scavenger receptors on macrophages. Lipoprotein (a) plasma concentrations correlate significantly with the synthetic rate of apo(a) and recent studies demonstrate that apo(a) expression is inhibited by ligands for farnesoid X receptor. Numerous gaps in our knowledge on Lp(a) function, biosynthesis, and the site of catabolism still exist. Nevertheless, new classes of therapeutic agents that have a significant Lp(a)-lowering effect such as apoB antisense oligonucleotides, microsomal triglyceride transfer protein inhibitors, cholesterol ester transfer protein inhibitors, and PCSK-9 inhibitors are currently in trials. Consensus reports of scientific societies are still prudent in recommending the measurement of Lp(a) routinely for assessing CVD risk. This is mainly caused by the lack of definite intervention studies demonstrating that lowering Lp(a) reduces hard CVD endpoints, a lack of effective medications for lowering Lp(a), the highly variable Lp(a) concentrations among different ethnic groups and the challenges associated with Lp(a) measurement. Here, we present our view on when to measure Lp(a) and how to deal with elevated Lp(a) levels in moderate and high-risk individuals.

FGF19 signaling cascade suppresses APOA gene expression.

OBJECTIVE: Lipoprotein(a) is a highly atherogenic lipoprotein, whose metabolism is poorly understood. Currently no safe drugs exists that lower elevated plasma lipoprotein(a) concentrations. We therefore focused on molecular mechanisms that influence apolipoprotein(a) (APOA) biosynthesis. METHODS AND RESULTS: Transgenic human APOA mice (tg-APO mice) were injected with 1 mg/kg of recombinant human fibroblast growth factor 19 (FGF19). This led to a significant reduction of plasma APOA and hepatic expression of APOA. Incubation of primary hepatocytes of tg-APOA mice with FGF19 induced ERK1/2 phosphorylation and, in turn, downregulated APOA expression. Repression of APOA by FGF19 was abrogated by specific ERK1/2 phosphorylation inhibitors. The FGF19 effect on APOA was attenuated by transfection of primary hepatocytes with siRNA against the FGF19 receptor 4 (FGFR4). Using promoter reporter assays, mutation analysis, gel shift, and chromatin immune-precipitation assays, an Ets-1 binding element was identified at -1630/-1615bp region in the human APOA promoter. This element functions as an Elk-1 binding site that mediates repression of APOA transcription by FGF19. CONCLUSIONS: These findings provide mechanistic insights into the transcriptional regulation of human APOA by FGF19. Further studies in the human system are required to substantiate our findings and to design therapeutics for hyper lipoprotein(a).

Nicotinic acid inhibits hepatic APOA gene expression: studies in humans and in transgenic mice.

Elevated plasma lipoprotein(a) (LPA) levels are recognized as an independent risk factor for cardiovascular diseases. Our knowledge on LPA metabolism is incomplete, which makes it difficult to develop LPA-lowering medications. Nicotinic acid (NA) is the main drug recommended for the treatment of patients with increased plasma LPA concentrations. The mechanism of NA in lowering LPA is virtually unknown. To study this mechanism, we treated transgenic (tg) APOA mice with NA and measured plasma APOA and hepatic mRNA levels. In addition, mouse and human primary hepatocytes were incubated with NA, and the expression of APOA was followed. Feeding 1% NA reduced plasma APOA and hepatic expression of APOA in tg-APOA mice. Experiments with cultured human and mouse primary hepatocytes in addition to reporter assays performed in HepG2 cells revealed that NA suppresses APOA transcription. The region between -1446 and -857 of the human APOA promoter harboring several cAMP response element binding sites conferred the negative effect of NA. In accordance, cAMP stimulated APOA transcription, and NA reduced hepatic cAMP levels. It is suggested that cAMP signaling might be involved in reducing APOA transcription, which leads to the lowering of plasma LPA.

Continuation of statin therapy in patients with presumed infection: a randomized controlled trial.

RATIONALE: In patients on prior statin therapy who are hospitalized for acute infections, current literature is unclear on whether statins should be continued during their hospitalization. OBJECTIVES: To test the hypothesis that continuation of therapy with statins influences the inflammatory response to infection and that cessation may cause an inflammatory rebound. METHODS: Prospective randomized double-blind placebo-controlled trial of atorvastatin (20 mg) or matched placebo in 150 patients on preexisting statin therapy requiring hospitalization for infection. MEASUREMENTS AND MAIN RESULTS: The primary end point was progression of sepsis during hospitalization. At baseline, the rate of severe sepsis was 32% in both groups. Compared with baseline, the odds ratio for severe sepsis declined in both groups: 0.43 placebo and 0.5 statins (Day 3) versus 0.14 placebo and 0.12 statins (Day 14). The rate of decline of severe sepsis was similar between the groups (odds ratio 1.17 [0.56-2.47], P = 0.7 Day 3; 0.85 [0.21-3.34], P = 0.8 Day 14). IL-6 and C-reactive protein declined in both groups with no statistically significant difference (P = 0.7 and P = 0.2, respectively). An increase in cholesterol occurred in the placebo group (P < 0.0001). Most patients were not critically ill. Hospital mortality was 6.6%, with no difference between the groups (6 [8%] of 75 statin group; 4 [5.3%] of 75 placebo group; P = 0.75). CONCLUSIONS: This study does not support a beneficial role of continuing preexisting statin therapy on sepsis and inflammatory parameters. Cessation of established statin therapy was not associated with an inflammatory rebound. Clinical trial registered at the Australian New Zealand Clinical Trials Registry (ACTRN 12605000756628).

Corrigendum to Synopsis of an integrated guidance for enhancing the care of familial hypercholesterolaemia: An Australian perspective [American Journal of Preventive Cardiology 6 (2021) 100151].

[This corrects the article DOI: 10.1016/j.ajpc.2021.100151.].

Synopsis of an integrated guidance for enhancing the care of familial hypercholesterolaemia: an Australian perspective.

INTRODUCTION: Familial hypercholesterolaemia (FH) is a common, heritable and preventable cause of premature coronary artery disease, with significant potential for positive impact on public health and healthcare savings. New clinical practice recommendations are presented in an abridged guidance to assist practitioners in enhancing the care of all patients with FH. MAIN RECOMMENDATIONS: Core recommendations are made on the detection, diagnosis, assessment and management of adults, children and adolescents with FH. There is a key role for general practitioners (GPs) working in collaboration with specialists with expertise in lipidology. Advice is given on genetic and cholesterol testing and risk notification of biological relatives undergoing cascade testing for FH; all healthcare professionals should develop skills in genomic medicine. Management is under-pinned by the precepts of risk stratification, adherence to healthy lifestyles, treatment of non-cholesterol risk factors, and appropriate use of low-density lipoprotein (LDL)-cholesterol lowering therapies, including statins, ezetimibe and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors. Recommendations on service design are provided in the full guidance. POTENTIAL IMPACT ON CARE OF FH: These recommendations need to be utilised using judicious clinical judgement and shared decision making with patients and families. Models of care need to be adapted to both local and regional needs and resources. In Australia new government funded schemes for genetic testing and use of PCSK9 inhibitors, as well as the National Health Genomics Policy Framework, will enable adoption of these recommendations. A broad implementation science strategy is, however, required to ensure that the guidance translates into benefit for all families with FH.

Molecular, Population, and Clinical Aspects of Lipoprotein(a): A Bridge Too Far?

There is now significant evidence to support an independent causal role for lipoprotein(a) (Lp(a)) as a risk factor for atherosclerotic cardiovascular disease. Plasma Lp(a) concentrations are predominantly determined by genetic factors. However, research into Lp(a) has been hampered by incomplete understanding of its metabolism and proatherogeneic properties and by a lack of suitable animal models. Furthermore, a lack of standardized assays to measure Lp(a) and no universal consensus on optimal plasma levels remain significant obstacles. In addition, there are currently no approved specific therapies that target and lower elevated plasma Lp(a), although there are recent but limited clinical outcome data suggesting benefits of such reduction. Despite this, international guidelines now recognize elevated Lp(a) as a risk enhancing factor for risk reclassification. This review summarises the current literature on Lp(a), including its discovery and recognition as an atherosclerotic cardiovascular disease risk factor, attempts to standardise analytical measurement, interpopulation studies, and emerging therapies for lowering elevated Lp(a) levels.

Is Lp(a) ready for prime time use in the clinic? A pros-and-cons debate.

Lipoprotein (a) (Lp(a)) is a cholesterol-rich lipoprotein known since 1963. In spite of extensive research on Lp(a), there are still numerous gaps in our knowledge relating to its function, biosynthesis and catabolism. One reason for this might be that apo(a), the characteristic glycoprotein of Lp(a), is expressed only in primates. Results from experiments using transgenic animals therefore may need verification in humans. Studies on Lp(a) are also handicapped by the great number of isoforms of apo(a) and the heterogeneity of apo(a)-containing fractions in plasma. Quantification of Lp(a) in the clinical laboratory for a long time has not been standardized. Starting from its discovery, reports accumulated that Lp(a) contributed to the risk of cardiovascular disease (CVD), myocardial infarction (MI) and stroke. Early reports were based on case control studies but in the last decades a great deal of prospective studies have been published that highlight the increased risk for CVD and MI in patients with elevated Lp(a). Final answers to the question of whether Lp(a) is ready for wider clinical use will come from intervention studies with novel selective Lp(a) lowering medications that are currently underway. This article expounds arguments for and against this proposition from currently available data.

Inflammation, complement activation and endothelial function in stable and unstable coronary artery disease.

BACKGROUND: Endothelial dysfunction plays an important role in the pathogenesis of coronary artery disease (CAD). Apart from traditional risk factors complement activation and inflammation may trigger and sustain endothelial dysfunction. We sought to assess the association between endothelial function, high sensitivity C-reactive protein (hs-CRP) and markers of complement activation in patients with either stable or unstable coronary artery disease. METHODS: We prospectively recruited 78 patients, 35 patients with stable angina pectoris (SAP) and 43 patients with unstable angina pectoris (UAP). Endothelial function was assessed as brachial artery reactivity (BAR). Hs-CRP, C3a, C5a and C1-Inhibitor (C1 inh.) were measured enzymatically. RESULTS: Patients with UAP showed higher median levels of hs-CRP and C3a compared to patients with SAP, while BAR was not significantly different between patient groups. In UAP patients, hs-CRP was significantly correlated with cholesterol (r=0.27, p<0.02), C3a (r=0.32, p<0.001) and C1 INH.(r=0.41, p<0.003), but not with flow mediated dilatation (r=0.09, P=0.41). Hs-CRP and C1 INH.were found to be independent predictors of UAP in a backward stepwise logistic regression model. CONCLUSIONS: We conclude that both hs-CRP, a marker of inflammation and C3a, a marker of complement activation are elevated in patients with UAP, but not in patients with SAP.

Relation of reduced preclinical left ventricular diastolic function and cardiac remodeling in overweight youth to insulin resistance and inflammation.

Insulin resistance (IR) and inflammation are associated with an increased risk of cardiovascular disease and may contribute to obesity cardiomyopathy. The earliest sign of obesity cardiomyopathy is impaired left ventricular (LV) diastolic function, which may be evident in obese children and adolescents. However, the precise metabolic basis of the impaired LV diastolic function remains unknown. The aims of this study were to evaluate cardiac structure and LV diastolic function by tissue Doppler imaging in overweight and obese (OW) youth and to assess the relative individual contributions of adiposity, IR, and inflammation to alterations in cardiac structure and function. We studied 35 OW (body mass index standard deviation score 2.0±0.8; non-IR n=19, IR n=16) and 34 non-OW youth (body mass index standard deviation score 0.1±0.7). LV diastolic function was reduced in OW youth compared with non-OW controls, as indicated by lower peak myocardial relaxation velocities (p<0.001) and greater filling pressures (p<0.001). OW youth also had greater LV mass index (p<0.001), left atrial volume index, and LV interventricular septal thickness (LV-IVS; both p=0.02). IR-OW youth had the highest LV filling pressures, LV-IVS, and relative wall thickness (all p<0.05). Homeostasis model of assessment-insulin resistance and C-reactive protein were negative determinants of peak myocardial relaxation velocity and positive predictors of filling pressure. Adiponectin was a negative determinant of LV-IVS, independent of obesity. In conclusion, OW youth with IR and inflammation are more likely to have adverse changes to cardiovascular structure and function which may predispose to premature cardiovascular disease in adulthood.