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

Identifying novel drug targets for calcific aortic valve disease through Mendelian randomization

BACKGROUND AND AIMS

Calcific aortic valve disease (CAVD) is characterized by progressive leaflet thickening and calcification, with no available pharmacological treatments. Plasma proteins play a pivotal role in disease regulation. This study aimed to uncover novel therapeutic targets for CAVD using Mendelian randomization (MR) integrated with transcriptomic analysis.

METHODS

Protein quantitative trait loci (pQTL) from the deCODE and UK Biobank Pharma Proteomics Project (UKB-PPP) plasma protein databases were used as exposure data. The FinnGen cohort (9870 cases, 402,311 controls) served as the discovery set, while the TARGET cohort (13,765 cases, 640,102 controls) provided validation. MR and summary data-based Mendelian randomization (SMR) were employed to screen for potential causal targets of CAVD. Colocalization analysis was conducted to assess whether CAVD and target proteins shared common causal SNPs. Additional analyses included trancriptomic profiling at multiple RNA levels. Protein-level validation was conducted via Western blot and immunostaining.

RESULTS

Six proteins (ANGPTL4, PCSK9, ITGAV, CTSB, GNPTG, and FURIN) with strong genetic colocalization were identified by MR and SMR analysis. Among these, cellular trancriptomic analysis revealed ANGPTL4 and ITGAV with significantly greater expression in osteogenic group, which was further validated in calcified aortic valves and osteogenic valvular interstitial cells in protein level.

CONCLUSIONS

This study identified six causal proteins with strong genetic colocalization for CAVD, with ANGPTL4 and ITGAV emerging as the most promising targets for further investigation.

Calcific aortic stenosis: omics-based target discovery and therapy development

Calcific aortic valve disease (CAVD) resulting in aortic stenosis (AS) is the most common form of valvular heart disease, affecting 2% of those over age 65. Those who develop symptomatic severe AS have an average further lifespan of <2 years without valve replacement, and three-quarters of these patients will develop heart failure, undergo valve replacement, or die within 5 years. There are no approved pharmaceutical therapies for AS, due primarily to a limited understanding of the molecular mechanisms that direct CAVD progression in the complex haemodynamic environment. Here, advances in efforts to understand the pathogenesis of CAVD and to identify putative drug targets derived from recent multi-omics studies [including (epi)genomics, transcriptomics, proteomics, and metabolomics] of blood and valvular tissues are reviewed. The recent explosion of single-cell omics-based studies in CAVD and the pathobiological and potential drug discovery insights gained from the application of omics to this disease area are a primary focus. Lastly, the translation of knowledge gained in valvular pathobiology into clinical therapies is addressed, with a particular emphasis on treatment regimens that consider sex-specific, renal, and lipid-mediated contributors to CAVD, and ongoing Phase I/II/III trials aimed at the prevention/treatment of AS are described.

Atherosclerosis, calcific aortic valve disease and mitral annular calcification: same or different?

There are similarities in the pathophysiologic mechanisms of atherosclerosis, calcific aortic valve disease (CAVD) and mitral annular calcification (MAC), however, medical treatment to slow or stop the progression of CAVD or MAC has been more elusive as compared to atherosclerosis. Atherosclerosis and CAVD share common demographic, clinical, protein, and genetic factors even more so than with MAC, which supports the possibility of shared medical therapies, though abrogating calcific extracellular vesicle shedding could be a common target for all three conditions. Herein, we summarize the overlapping and distinct pathways for further investigation, as well as key areas where additional research is needed.

Association between triglyceride-glucose-body mass index and risk of aortic stenosis progression in patients with non-severe aortic stenosis: a retrospective cohort study

BACKGROUND

Triglyceride-glucose-BMI (TyG-BMI) index is a surrogate marker of insulin resistance and an important predictor of cardiovascular disease. However, the predictive value of TyG-BMI index in the progression of non-severe aortic stenosis (AS) is still unclear.

METHODS

The present retrospective observational study was conducted using patient data from Aortic valve diseases RISk facTOr assessmenT andprognosis modeL construction (ARISTOTLE). A total of 190 patients were recruited from one-center. Patients were divided into two groups according to the cut-off value of TyG-BMI index (Ln[triglycerides (mg/dL)* glucose (mg/dL)/2]*BMI). Cox regression and restricted subgroup analysis were used to evaluate the association of TyG-BMI index and progression of non-severe AS.

RESULTS

A total of 190 patients (mean age 72.52 ± 11.97 years, 51.58% male) were included in the study. During a median follow-up period of 27.48 months, 44 participants experienced disease progression. The cut-off of the TyG-BMI index is 239. After fully adjusting for confounding factors, high TyG-BMI index group was associated with a 2.219-fold higher risk of aortic stenosis progression (HR 2.219, 95%CI 1.086-4.537, p = 0.029).

CONCLUSION

TyG-BMI index was significantly associated with a higher risk of progression to non-severe AS. TyG-BMI index, as an effective alternative indicator of IR, can identify people at high risk of AS progression at an early stage of the disease, thereby improving the prognosis and reducing the socio-economic burden.

Aortopathy: Effects of Lipid-Lowering Therapy

Aortopathies can be congenital or acquired. Aortic atherosclerosis, abdominal aortic aneurysm, and degenerative aortic stenosis are some of the major manifestations of acquired aortopathy. Dyslipidemia, an imbalance of plasma lipid levels, is strongly associated with common aortopathies. A relationship between abdominal aortic aneurysm, degenerative aortic stenosis, and dyslipidemia has been identified in the literature but finding effective preventive strategies has been challenging. Nevertheless, lipid-lowering therapy remains a mainstay of both treatment and prevention. In patients with aortic atheroma, statins were found to be protective through the review of this study. There is currently no place for statins in the treatment or prevention of disease progression in patients with calcific aortic stenosis. Their low cost, widespread availability, and strong safety profile tip the risk-to-benefit ratio toward statins for abdominal aortic aneurysms but more research is needed. A review of proprotein convertase subtilisin/kexin type 9 inhibitors may yield similar benefits for all aortopathy patients; however, those results are not yet available.

Lipoprotein(a) and thromboembolism: current state of knowledge and unsolved issues

Lipoprotein(a) [Lp(a)], a low-density lipoprotein-like particle containing a highly polymorphic apolipoprotein(a) [apo(a)] homologous in > 80% to plasminogen, was identified as a genetically determined independent risk factor for cardiovascular disease. Elevated Lp(a) levels, found in about 20% of Europeans, are strongly linked to higher rates of myocardial infarction, major adverse cardiac events, accelerated plaque progression, ischemic stroke (especially in younger adults), and calcific aortic valve disease. However, its role in venous thromboembolism, including atypical locations like cerebral and retinal vein thrombosis, remains controversial despite several shared mechanisms underlying arterial and venous thromboembolism. The most robust evidence supports antifibrinolytic properties of elevated Lp(a), particularly smaller apo(a) isoforms, which inhibit plasminogen activation mainly by interacting with the tissue-type plasminogen activator, plasminogen, and fibrin. Other prothrombotic mechanisms include increased synthesis of plasminogen activator inhibitor (PAI-1), formation of denser fibrin networks composed of thinner fibers, less susceptible to lysis, increased platelet activation, enhanced oxidation of phospholipids leading to a low-grade proinflammatory state, upregulated tissue factor expression, and suppression of tissue factor pathway inhibitor. Targeted Lp(a) lowering therapies are currently being tested in randomized clinical trials and could potentially have clinically relevant antithrombotic effects, evidenced by the reduced risk of thromboembolism. This review summarizes the available data on the prothrombotic and antifibrinolytic actions of Lp(a), along with clinical evidence for the increased risk of thromboembolic events related to elevated Lp(a). It also introduces new concepts to explain discrepant clinical results regarding venous events, highlighting the impact of oxidized phospholipids on a prothrombotic state under conditions of high Lp(a).

Role of Lipoprotein (A) in aortic valve stenosis: Novel disease mechanisms and emerging pharmacotherapeutic approaches

Lipoprotein(a) (Lp(a)) has garnered increasing attention as a significant contributor to the pathogenesis of aortic stenosis (AS), prompting a focused investigation into innovative pharmacological strategies to target this lipoprotein and its associated risks. Despite its recognized role in AS progression, Lp(a) often remains overlooked in clinical assessments, mirroring the broader challenges observed in holistic disease management. This review delves into the mechanistic intricacies of Lp(a) involvement in AS pathophysiology and its potential as a therapeutic target. Drawing parallels with the imperative for healthcare providers to proactively engage with patients regarding treatment regimens, this review underscores the essential role of cardiologists and physicians in recognizing and addressing Lp(a) as a modifiable risk factor in AS management. Furthermore, it explores promising avenues of novel drug approaches, including emerging pharmacotherapies and targeted interventions, aimed at modulating Lp(a) levels and attenuating AS progression. By navigating the complexities of Lp(a) modulation and its implications for AS management, this review aims to bridge critical gaps in understanding and clinical practice, ultimately optimizing treatment strategies and improving patient outcomes in the realm of AS therapeutics.

Genetics of Calcific Aortic Stenosis: A Systematic Review

Background: Calcific aortic stenosis is the most prevalent valvular abnormality in the Western world. Factors commonly associated with calcific aortic stenosis include advanced age, male sex, hypertension, diabetes and impaired renal function. This review synthesises the existing literature on genetic associations with calcific aortic stenosis. Methods: A systematic search was conducted in the PubMed, Ovid and Cochrane libraries from inception to 21 July 2024 to identify human studies investigating the genetic factors involved in calcific aortic stenosis. From an initial pool of 1392 articles, 78 were selected for full-text review and 31 were included in the final qualitative synthesis. The risk of bias in these studies was assessed using the Newcastle Ottawa Scale. Results: Multiple genes have been associated with calcific aortic stenosis. These genes are involved in different biological pathways, including the lipid metabolism pathway (PLA, LDL, APO, PCSK9, Lp-PLA2, PONS1), the inflammatory pathway (IL-6, IL-10), the calcification pathway (PALMD, TEX41) and the endocrine pathway (PTH, VIT D, RUNX2, CACNA1C, ALPL). Additional genes such as NOTCH1, NAV1 and FADS1/2 influence different pathways. Mechanistically, these genes may promote a pro-inflammatory and pro-calcific environment in the aortic valve itself, leading to increased osteoblastic activity and subsequent calcific degeneration of the valve. Conclusions: Numerous genetic associations contribute to calcific aortic stenosis. Recognition of these associations can enhance risk stratification for individuals and their first-degree relatives, facilitate family screening, and importantly, pave the way for targeted therapeutic interventions focusing on the identified genetic factors. Understanding these genetic factors can also lead to gene therapy to prevent calcific aortic stenosis in the future.

Association of Lipoprotein(a) With Severe Degenerative Aortic Valve Stenosis

Background

Lipoprotein(a) (Lp[a]) is associated with the development of aortic valve calcification.

Objectives

The aim of this study was to evaluate the association between the serum level of Lp(a) and the development of severe degenerative aortic stenosis (AS) and subsequent aortic valve replacement (AVR).

Methods

A total of 44,742 patients with Lp(a) measurements and echocardiography at baseline evaluation between 2000 and 2020 were included from a single tertiary heart center. The primary outcome was the development of severe degenerative AS, defined as a transaortic maximal velocity of ≥4.0 m/s.

Results

During a median follow-up period of 6.8 years (Q1-Q3: 2.3-12.4 years), severe degenerative AS was diagnosed in 472 patients (1.1%), and subsequent AVR was performed in 387 patients (0.9%). Lp(a) levels were associated with risk for severe degenerative AS, with levels of 30 to 50, 50 to 100, and >100 mg/dL demonstrating adjusted HRs of 1.02 (95% CI: 0.78-1.34; P = 0.88), 1.18 (95% CI: 0.91-1.53; P = 0.22), and 1.96 (95% CI: 1.31-2.94; P = 0.001) compared to <30 mg/dL. Similarly, the risk for AVR due to severe degenerative AS was significantly associated with higher levels of Lp(a) (>100 mg/dL) (adjusted HR: 2.05; 95% CI: 1.31-3.19; P = 0.002). Such associations were not observed in the development of severe bicuspid (P = 0.63) or rheumatic (P = 0.96) AS.

Conclusions

Lp(a) levels >100 mg/dL were significantly associated with risk for severe degenerative AS and subsequent AVR, regardless of the baseline severity of AS. Such associations were not observed in other etiologies of severe AS.

Current Management and Therapy of Severe Aortic Stenosis and Future Perspective

Intervention for severe aortic stenosis (AS) has dramatically progressed since the introduction of transcatheter aortic valve replacement (TAVR). Decades ago, controversies existed regarding comparing clinical outcomes between TAVR and surgical aortic valve replacement (SAVR) in various risk profiles. Recently, we discussed the durability of transcatheter heart valves and their lifetime management after aortic valve replacement (AVR). Regarding the management of AS, we discuss the appropriate timing of intervention for severe aortic stenosis, especially in asymptomatic patients. In spite of dramatic progression of intervention for AS, there are no established medications available to prevent or slow the progression of AS at present. Basic research and genome studies have suggested several targets associated with the progression of aortic valve calcification. Randomized controlled trials evaluating the efficacy of medications to prevent AS progression are ongoing, which might lead to new strategies for AS management. In this review, we summarize the current management of AS and the drugs expected to prevent the progression of AS.

Unmet needs and knowledge gaps in aortic stenosis: A position paper from the Heart Valve Council of the French Society of Cardiology

Nowadays, valvular heart disease remains a significant challenge among cardiovascular diseases, affecting millions of people worldwide and exerting substantial pressure on healthcare systems. Within the spectrum of valvular heart disease, aortic stenosis is the most common valvular lesion in developed countries. Despite notable advances in understanding its pathophysiological processes, improved cardiovascular imaging techniques and expanding therapeutic options in recent years, there are still unmet needs and knowledge gaps regarding aortic stenosis pathophysiology, severity assessment, management and decision-making strategy. This review, prepared on behalf of the Heart Valve Council of the French Society of Cardiology, describes these gaps and future research perspectives to improve the outcome of patients with aortic stenosis.

Moderate Aortic Stenosis-Advanced Imaging, Risk Assessment, and Treatment Strategies

Moderate aortic stenosis is increasingly recognized as a disease entity with poor prognosis. Diagnosis of moderate aortic stenosis may be complemented by laboratory tests and advanced imaging techniques focused at detecting signs of cardiac damage such as increase of cardiac enzymes (N-terminal pro-B-type Natriuretic Peptide, troponin), left ventricular remodeling (hypertrophy, reduced left ventricular ejection fraction), or myocardial fibrosis. Therapy should include guideline-directed optimal medical therapy for heart failure. Patients with signs of cardiac damage may benefit from early intervention, which is the focus of several ongoing randomized controlled trials. As yet, no evidence-based therapy exists to halt the progression of aortic valve calcification.

Lipoprotein (a) and lipid-lowering treatment from the perspective of a cardiac surgeon. An impact on the prognosis in patients with aortic valve replacement and after heart transplantation

Lipoprotein(a) is a recognized risk factor for ASCVD. There is still no targeted therapy for Lp(a), however, drugs such as pelacarsen, olpasiran, zerlasiran, lepodisiran and muvalaplin are in clinical trials and have been shown to be effective in significantly reducing Lp(a) levels. Moreover, elevated Lp(a) levels significantly affect the prognosis of patients after aortic valve replacement (AVR) and heart transplantation (HTx). Therefore, the assessment of Lp(a) concentration in these patients will allow for a more accurate stratification of their cardiovascular risk, and the possibility of lowering Lp(a) will allow for the optimization of this risk. In this article, we summarized the most important information regarding the role of Lp(a) and lipid-lowering treatment in patients after AVR and HTx.

Association between evolocumab use and slow progression of aortic valve stenosis

No medications have been reported to inhibit the progression of aortic valve stenosis (AS). The present study aimed to investigate whether evolocumab use is related to the slow progression of AS evaluated by serial echocardiography. This was a retrospective observational study from 2017 to 2022 at Yokohama City University Medical Center. Patients aged ≥ 18 with moderate AS were included. Exclusion criteria were (1) mild AS; (2) severe AS defined by maximum aortic valve (AV) velocity ≥ 4.0 m/s; and/or (3) no data of annual follow-up echocardiography. The primary endpoint was the association between evolocumab use and annual changes in the maximum AV-velocity or peak AV-pressure gradient (PG). A total of 57 patients were enrolled: 9 patients treated with evolocumab (evolocumab group), and the other 48 patients assigned to a control group. During a median follow-up of 33 months, the cumulative incidence of AS events (a composite of all-cause death, AV intervention, or unplanned hospitalization for heart failure) was 11% in the evolocumab group and 58% in the control group (P = 0.012). Annual change of maximum AV-velocity or peak AV-PG from the baseline to the next year was 0.02 (- 0.18 to 0.22) m/s per year or 0.60 (- 4.20 to 6.44) mmHg per year in the evolocumab group, whereas it was 0.29 (0.04-0.59) m/s per year or 7.61 (1.46-16.48) mmHg per year in the control group (both P < 0.05). Evolocumab use was associated with slow progression of AS and a low incidence of AS events in patients with moderate AS.

Genetic proxy of lipid-lowering drugs and calcific aortic valve stenosis: A Mendelian randomization study

Background

Lipid metabolism plays an important role in the pathogenesis and development of calcific aortic valve stenosis. Our aim was to evaluate the causal effect of lipid-lowering drugs, such as low-density lipoprotein cholesterol (LDL-C) lowering and triglyceride lowering drugs, on the outcome of aortic valve stenosis using a two-sample Mendelian randomization (MR) study.

Methods

We used two genetic tools to represent the exposure of lipid-lowering drugs, including expression quantitative trait loci for the expression of drug target genes, and genetic variants within or near drug target genes that are associated with LDL-C and triglyceride concentrations from Genome-Wide Association Studies (GWAS). Effect estimates were calculated using summary-data-based MR (SMR) and inverse-variance-weighted MR (IVW-MR) analysis.

Results

Based on the results of SMR and IVW-MR analysis, LDL-C-lowering PCSK9 inhibitors have potential in reducing the risk of aortic valve stenosis (for SMR, OR: 1.044; 95%CI: 1.002-1.404; P = 0.047; for IVW-MR, OR: 1.647, 95%CI: 1.316-2.062, P < 0.001). However, no significant association was observed between triglyceride target gene expression, as well as triglyceride-lowering drugs, and aortic valve stenosis.

Conclusion

This two-sample drug-targeted MR study suggests a potential causal relationship between PCSK9 inhibitors and the reduction of calcific aortic valve stenosis risk.

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).

Pathological Mechanism and Treatment of Calcified Aortic Stenosis

Calcified aortic stenosis (AS) is one of the most common valvular heart diseases worldwide, characterized by progressive fibrocalcific remodeling and thickening of the leaflets, which ultimately leads to obstruction of blood flow. Its pathobiology is an active and complicated process, involving endothelial cell dysfunction, lipoprotein deposition and oxidation, chronic inflammation, phenotypic transformation of valve interstitial cells, neovascularization, and intravalvular hemorrhage. To date, no targeted drug has been proven to slow down or prevent disease progression. Aortic valve replacement is still the optimal treatment of AS. This article reviews the etiology, diagnosis, and management of calcified aortic stenosis and proposes novel potential therapeutic targets.

PCSK9 and Lipid Metabolism: Genetic Variants, Current Therapies, and Cardiovascular Outcomes

Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a crucial role in the modulation of lipid metabolism as a critical negative regulator of hepatic low-density lipoprotein receptor (LDLR) levels and circulating low-density lipoprotein (LDL) clearance. Numerous gain-of-function (GOF) mutations in PCSK9 have been identified as causing familial hypercholesterolemia (FH) by reducing LDLR levels, and loss-of-function (LOF) mutations associated with a hypercholesterolemia phenotype protective against atherosclerosis. PCSK9 represents an example of successful translational research resulting in the identification of PCSK9 as a major drug target for a lipid-lowering therapy. To explore the genetic constitution of PCSK9 and its biologic role, in this review, we summarize the current evidence of clinically significant PCSK9 genetic variants involved in lipid metabolism as well as emphasize the importance of PCSK9 inhibition for the improvement of cardiovascular outcomes by conducting a meta-analysis of the available data on the incidence of cardiovascular disease events.

Identifying People at High Risk for Severe Aortic Stenosis: Aortic Valve Calcium Versus Lipoprotein(a) and Low-Density Lipoprotein Cholesterol

BACKGROUND

Aortic valve calcification (AVC), Lp(a) [lipoprotein(a)], and low-density lipoprotein cholesterol (LDL-C) are associated with severe aortic stenosis (AS). We aimed to determine which of these risk factors were most strongly associated with the risk of incident severe AS.

METHODS

A total of 6792 participants from the MESA study (Multi-Ethnic Study of Atherosclerosis) had computed tomography-quantified AVC, Lp(a), and LDL-C values at MESA visit 1 (2000-2002). We calculated the absolute event rate of incident adjudicated severe AS per 1000 person-years and performed multivariable adjusted Cox proportional hazards regression.

RESULTS

The mean age was 62 years old, and 47% were women. Over a median 16.7-year follow-up, the rate of incident severe AS increased exponentially with higher AVC, regardless of Lp(a) or LDL-C values. Participants with AVC=0 had a very low rate of severe AS even with elevated Lp(a) ≥50 mg/dL (<0.1/1000 person-years) or LDL-C ≥130 mg/dL (0.1/1000 person-years). AVC >0 was strongly associated with severe AS when Lp(a) <50 mg/dL hazard ratio (HR) of 33.8 (95% CI, 16.4-70.0) or ≥50 mg/dL HR of 61.5 (95% CI, 7.7-494.2) and when LDL-C <130 mg/dL HR of 31.1 (95% CI, 14.4-67.1) or ≥130 mg/dL HR of 50.2 (95% CI, 13.2-191.9).

CONCLUSIONS

AVC better identifies people at high risk for severe AS compared with Lp(a) or LDL-C, and people with AVC=0 have a very low long-term rate of severe AS regardless of Lp(a) or LDL-C level. These results suggest AVC should be the preferred prognostic risk marker to identify patients at high risk for severe AS, which may help inform participant selection for future trials testing novel strategies to prevent severe AS.

Lipoprotein(a): Emerging insights and therapeutics

The strong association between lipoprotein (a) [Lp(a)] and atherosclerotic cardiovascular disease has led to considerations of Lp(a) being a potential target for mitigating residual cardiovascular risk. While approximately 20 % of the population has an Lp(a) level greater than 50 mg/dL, there are no currently available pharmacological lipid-lowering therapies that have demonstrated substantial reduction in Lp(a). Novel therapies to lower Lp(a) include antisense oligonucleotides and small-interfering ribonucleic acid molecules and have shown promising results in phase 2 trials. Phase 3 trials are currently underway and will test the causal relationship between Lp(a) and ASCVD and whether lowering Lp(a) reduces cardiovascular outcomes. In this review, we summarize emerging insights related to Lp(a)'s role as a risk-enhancing factor for ASCVD, association with calcific aortic stenosis, effects of existing therapies on Lp(a) levels, and variations amongst patient populations. The evolving therapeutic landscape of emerging therapeutics is further discussed.

AVCAPIR: A Novel Procalcific PIWI-Interacting RNA in Calcific Aortic Valve Disease

BACKGROUND

Calcification of the aortic valve leads to increased leaflet stiffness and consequently results in the development of calcific aortic valve disease (CAVD). However, the underlying molecular and cellular mechanisms of calcification remain unclear. Here, we identified a novel aortic valve calcification-associated PIWI-interacting RNA (piRNA; AVCAPIR) that increases valvular calcification and promotes CAVD progression.

METHODS

Using piRNA sequencing, we identified piRNAs contributing to the pathogenesis of CAVD that we termed AVCAPIRs. High-cholesterol diet-fed ApoE-/- mice with AVCAPIR knockout were used to examine the role of AVCAPIR in aortic valve calcification (AVC). Gain- and loss-of-function assays were conducted to determine the role of AVCAPIR in the induced osteogenic differentiation of human valvular interstitial cells. To dissect the mechanisms underlying AVCAPIR-elicited procalcific effects, we performed various analyses, including an RNA pulldown assay followed by liquid chromatography-tandem mass spectrometry, methylated RNA immunoprecipitation sequencing, and RNA sequencing. RNA pulldown and RNA immunoprecipitation assays were used to study piRNA interactions with proteins.

RESULTS

We found that AVCAPIR was significantly upregulated during AVC and exhibited potential diagnostic value for CAVD. AVCAPIR deletion markedly ameliorated AVC in high-cholesterol diet-fed ApoE-/- mice, as shown by reduced thickness and calcium deposition in the aortic valve leaflets, improved echocardiographic parameters (decreased peak transvalvular jet velocity and mean transvalvular pressure gradient, as well as increased aortic valve area), and diminished levels of osteogenic markers (Runx2 and Osterix) in aortic valves. These results were confirmed in osteogenic medium-induced human valvular interstitial cells. Using unbiased protein-RNA screening and molecular validation, we found that AVCAPIR directly interacts with FTO (fat mass and obesity-associated protein), subsequently blocking its N6-methyladenosine demethylase activity. Further transcriptomic and N6-methyladenosine modification epitranscriptomic screening followed by molecular validation confirmed that AVCAPIR hindered FTO-mediated demethylation of CD36 mRNA transcripts, thus enhancing CD36 mRNA stability through the N6-methyladenosine reader IGF2BP1 (insulin-like growth factor 2 mRNA binding protein 1). In turn, the AVCAPIR-dependent increase in CD36 stabilizes its binding partner PCSK9 (proprotein convertase subtilisin/kexin type 9), a procalcific gene, at the protein level, which accelerates the progression of AVC.

CONCLUSIONS

We identified a novel piRNA that induced AVC through an RNA epigenetic mechanism and provide novel insights into piRNA-directed theranostics in CAVD.

The future of valvular heart disease assessment and therapy

Valvular heart disease (VHD) is becoming more prevalent in an ageing population, leading to challenges in diagnosis and management. This two-part Series offers a comprehensive review of changing concepts in VHD, covering diagnosis, intervention timing, novel management strategies, and the current state of research. The first paper highlights the remarkable progress made in imaging and transcatheter techniques, effectively addressing the treatment paradox wherein populations at the highest risk of VHD often receive the least treatment. These advances have attracted the attention of clinicians, researchers, engineers, device manufacturers, and investors, leading to the exploration and proposal of treatment approaches grounded in pathophysiology and multidisciplinary strategies for VHD management. This Series paper focuses on innovations involving computational, pharmacological, and bioengineering approaches that are transforming the diagnosis and management of patients with VHD. Artificial intelligence and digital methods are enhancing screening, diagnosis, and planning procedures, and the integration of imaging and clinical data is improving the classification of VHD severity. The emergence of artificial intelligence techniques, including so-called digital twins-eg, computer-generated replicas of the heart-is aiding the development of new strategies for enhanced risk stratification, prognostication, and individualised therapeutic targeting. Various new molecular targets and novel pharmacological strategies are being developed, including multiomics-ie, analytical methods used to integrate complex biological big data to find novel pathways to halt the progression of VHD. In addition, efforts have been undertaken to engineer heart valve tissue and provide a living valve conduit capable of growth and biological integration. Overall, these advances emphasise the importance of early detection, personalised management, and cutting-edge interventions to optimise outcomes amid the evolving landscape of VHD. Although several challenges must be overcome, these breakthroughs represent opportunities to advance patient-centred investigations.

Lp(a) - an overlooked risk factor

Lipoprotein(a) (Lp(a)) is an increasingly discussed and studied risk factor for atherosclerotic cardiovascular disease and aortic valve stenosis. Many genetic and epidemiological studies support the important causal role that Lp(a) plays in the incidence of cardiovascular disease. Although dependent upon the threshold and unit of measurement of Lp(a), most estimates suggest between 20 and 30% of the world's population have elevated serum levels of Lp(a). Lp(a) levels are predominantly mediated by genetics and are not significantly modified by lifestyle interventions. Efforts are ongoing to develop effective pharmacotherapies to lower Lp(a) and to determine if lowering Lp(a) with these medications ultimately decreases the incidence of adverse cardiovascular events. In this review, the genetics and pathophysiological properties of Lp(a) will be discussed as well as the epidemiological data demonstrating its impact on the incidence of cardiovascular disease. Recommendations for screening and how to currently approach patients with elevated Lp(a) are also noted. Finally, the spectrum of pharmacotherapies under development for Lp(a) lowering is detailed.

Autotaxin inhibition attenuates the aortic valve calcification by suppressing inflammation-driven fibro-calcific remodeling of valvular interstitial cells

BACKGROUND

Patients with fibro-calcific aortic valve disease (FCAVD) have lipid depositions in their aortic valve that engender a proinflammatory impetus toward fibrosis and calcification and ultimately valve leaflet stenosis. Although the lipoprotein(a)-autotaxin (ATX)-lysophosphatidic acid axis has been suggested as a potential therapeutic target to prevent the development of FCAVD, supportive evidence using ATX inhibitors is lacking. We here evaluated the therapeutic potency of an ATX inhibitor to attenuate valvular calcification in the FCAVD animal models.

METHODS

ATX level and activity in healthy participants and patients with FCAVD were analyzed using a bioinformatics approach using the Gene Expression Omnibus datasets, enzyme-linked immunosorbent assay (ELISA), immunohistochemistry, and western blotting. To evaluate the efficacy of ATX inhibitor, interleukin-1 receptor antagonist-deficient (Il1rn-/-) mice and cholesterol-enriched diet-induced rabbits were used as the FCAVD models, and primary human valvular interstitial cells (VICs) from patients with calcification were employed.

RESULTS

The global gene expression profiles of the aortic valve tissue of patients with severe FCAVD demonstrated that ATX gene expression was significantly upregulated and correlated with lipid retention (r = 0.96) or fibro-calcific remodeling-related genes (r = 0.77) in comparison to age-matched non-FCAVD controls. Orally available ATX inhibitor, BBT-877, markedly ameliorated the osteogenic differentiation and further mineralization of primary human VICs in vitro. Additionally, ATX inhibition significantly attenuated fibrosis-related factors' production, with a detectable reduction of osteogenesis-related factors, in human VICs. Mechanistically, ATX inhibitor prohibited fibrotic changes in human VICs via both canonical and non-canonical TGF-β signaling, and subsequent induction of CTGF, a key factor in tissue fibrosis. In the in vivo FCAVD model system, ATX inhibitor exposure markedly reduced calcific lesion formation in interleukin-1 receptor antagonist-deficient mice (Il1rn-/-, P = 0.0210). This inhibition ameliorated the rate of change in the aortic valve area (P = 0.0287) and mean pressure gradient (P = 0.0249) in the FCAVD rabbit model. Moreover, transaortic maximal velocity (Vmax) was diminished with ATX inhibitor administration (mean Vmax = 1.082) compared to vehicle control (mean Vmax = 1.508, P = 0.0221). Importantly, ATX inhibitor administration suppressed the effects of a high-cholesterol diet and vitamin D2-driven fibrosis, in association with a reduction in macrophage infiltration and calcific deposition, in the aortic valves of this rabbit model.

CONCLUSIONS

ATX inhibition attenuates the development of FCAVD while protecting against fibrosis and calcification in VICs, suggesting the potential of using ATX inhibitors to treat FCAVD.

The Relationship Between Endocan and Serum Inflammatory Markers in Patients with Senile Calcific Aortic Stenosis

BACKGROUND

Endocan is an indicator of many pathologies accompanied by inflammation, endothelial cell activation, and dysfunction. In this study, we examined the relationship between degenerative aortic sclerosis, which progresses in a similar pathophysiologic mechanism as atherosclerosis, and serum inflammatory markers and endocan levels.

METHODS

A total of 155 patients without known coronary artery disease, aged between 65 and 80 years, were consecutively included in the prospective cross-sectional study. The study population was analyzed in 4 different groups. The control group consisted of patients with normal aortic valve structure, while patients with aortic stenosis were classified as mild aortic stenosis (2-2.9 m/s), moderate aortic stenosis (3-3.9 m/s), and severe aortic stenosis (≥ 4 m/s) according to their aortic velocity. While there were 39 patients in the control group, there were 58, 24, and 34 patients in the mild, moderate, and severe aortic stenosis groups, respectively.

RESULTS

There was no statistically significant difference between the groups in terms of patient distribution and characteristics. History of dyspnea and angina was correlated with the severity of aortic stenosis (P <.001). In this study, no statistically significant correlation was found between serum endocan levels and the severity of aortic stenosis (control group: 17.3 ± 6.3 ng/mL, mild aortic stenosis: 17.6 ± 8.7 ng/mL, moderate aortic stenosis: 16.3 ± 3.8 ng/mL, severe aortic stenosis: 15.2 ± 5.9 ng/mL, P =.396). However, it was figured out that there was a positive correlation between endocan levels and hemoglobin (Hg) (r = 0.308, P =.001), platelet (PLT) (r = 0.320, P <.001), and albumin (Alb) (r = 0.206, P =.026).

CONCLUSION

In this study, no significant correlation was found between serum endocan levels and the severity of aortic stenosis. On the other hand, there was a positive correlation between endocan levels and Hg, PLT, and Alb.

Lipoprotein(a) and calcific aortic valve disease: current evidence and future directions

PURPOSE OF REVIEW

Calcific aortic valve disease (CAVD), the most common cause of aortic stenosis (AS), is characterized by slowly progressive fibrocalcific remodelling of the valve cusps. Once symptomatic, severe AS is associated with poor survival unless surgical or transcatheter valve replacement is performed. Unfortunately, no pharmacological interventions have been demonstrated to alter the natural history of CAVD. Lipoprotein(a) [Lp(a)], a low-density lipoprotein-like particle, has been implicated in the pathophysiology of CAVD.

RECENT FINDINGS

The mechanisms by which Lp(a) results in CAVD are not well understood. However, the oxidized phospholipids carried by Lp(a) are considered a crucial mediator of the disease process. An increasing number of studies demonstrate a causal association between plasma Lp(a) levels and frequency of AS and need for aortic valve replacement, which is independent of inflammation, as measured by plasma C-reactive protein levels. However, not all studies show an association between Lp(a) and increased progression of calcification in individuals with established CAVD.

SUMMARY

Epidemiologic, genetic, and Mendelian randomization studies have collectively suggested that Lp(a) is a causal risk factor for CAVD. Whether Lp(a)-lowering can prevent initiation or slow progression of CAVD remains to be demonstrated.

Lp(a) in the Pathogenesis of Aortic Stenosis and Approach to Therapy with Antisense Oligonucleotides or Short Interfering RNA

To date, no medical therapy can slow the progression of aortic stenosis. Fibrocalcific stenosis is the most frequent form in the general population and affects about 6% of the elderly population. Over the years, diagnosis has evolved thanks to echocardiography and computed tomography assessments. The application of artificial intelligence to electrocardiography could further implement early diagnosis. Patients with severe aortic stenosis, especially symptomatic patients, have valve repair as their only therapeutic option by surgical or percutaneous technique (TAVI). The discovery that the pathogenetic mechanism of aortic stenosis is similar to the atherosclerosis process has made it possible to evaluate the hypothesis of medical therapy for aortic stenosis. Several drugs have been tested to reduce low-density lipoprotein (LDL) and lipoprotein(a) (Lp(a)) levels, inflammation, and calcification. The Proprotein Convertase Subtilisin/Kexin type 9 inhibitors (PCSK9-i) could decrease the progression of aortic stenosis and the requirement for valve implantation. Great interest is related to circulating Lp(a) levels as causally linked to degenerative aortic stenosis. New therapies with ASO (antisense oligonucleotides) and siRNA (small interfering RNA) are currently being tested. Olpasiran and pelacarsen reduce circulating Lp(a) levels by 85-90%. Phase 3 studies are underway to evaluate the effect of these drugs on cardiovascular events (cardiovascular death, non-fatal myocardial injury, and non-fatal stroke) in patients with elevated Lp(a) and CVD (cardiovascular diseases). For instance, if a reduction in Lp(a) levels is associated with aortic stenosis prevention or progression, further prospective clinical trials are warranted to confirm this observation in this high-risk population.

Exploring the significance of epicardial adipose tissue in aortic valve stenosis and left ventricular remodeling: Unveiling novel therapeutic and prognostic markers of disease

Aortic stenosis (AS) is a dynamic degenerative process that shares many pathophysiological features with atherogenesis, from initial proinflammatory calcification and focal thickening of the valve leaflets to obstruction of left ventricular outflow due to superimposed of severe calcification and immobilization of the valve leaflets. As the prevalence increases with age, AS is expected to become one of the most common heart diseases worldwide. In both obese and nonobese patients, persistent thickening of epicardial adipose tissue (EAT) is associated with a shift in its normal metabolic functions toward a dysmetabolic and proatherogenic phenotype that may impair the physiology of adjacent coronary arteries and promote the occurrence of coronary atherosclerosis. In tight analogy with atherosclerosis, recent clinical evidence indicates that EAT may also exert a deleterious role in promoting AS and contributing to myocardial dysfunction, leading to increased health risk for elderly patients with AS and an economic burden on the health care system. This review discusses the clinical and pathologic evidence for the association between EAT and AS and concomitant left ventricular hypertrophy, and provides new insights for the future direction of AS diagnosis and treatment.

The Complex Relationship between Hypoxia Signaling, Mitochondrial Dysfunction and Inflammation in Calcific Aortic Valve Disease: Insights from the Molecular Mechanisms to Therapeutic Approaches

Calcific aortic valve stenosis (CAVS) is among the most common causes of cardiovascular mortality in an aging population worldwide. The pathomechanisms of CAVS are such a complex and multifactorial process that researchers are still making progress to understand its physiopathology as well as the complex players involved in CAVS pathogenesis. Currently, there is no successful and effective treatment to prevent or slow down the disease. Surgical and transcatheter valve replacement represents the only option available for treating CAVS. Insufficient oxygen availability (hypoxia) has a critical role in the pathogenesis of almost all CVDs. This process is orchestrated by the hallmark transcription factor, hypoxia-inducible factor 1 alpha subunit (HIF-1α), which plays a pivotal role in regulating various target hypoxic genes and metabolic adaptations. Recent studies have shown a great deal of interest in understanding the contribution of HIF-1α in the pathogenesis of CAVS. However, it is deeply intertwined with other major contributors, including sustained inflammation and mitochondrial impairments, which are attributed primarily to CAVS. The present review aims to cover the latest understanding of the complex interplay effect of hypoxia signaling pathways, mitochondrial dysfunction, and inflammation in CAVS. We propose further hypotheses and interconnections on the complexity of these impacts in a perspective of better understanding the pathophysiology. These interplays will be examined considering recent studies that shall help us better dissect the molecular mechanism to enable the design and development of potential future therapeutic approaches that can prevent or slow down CAVS processes.

Stroke and Noninfective Native Valvular Disease

PURPOSE OF REVIEW

Embolic stroke of undetermined source is a challenging clinical entity. While less common than atrial fibrillation and endocarditis, many noninfective heart valve lesions have been associated with stroke and may be considered as culprits for cerebral infarcts when other more common causes are excluded. This review discusses the epidemiology, pathophysiology, and management of noninfective valvular diseases that are commonly associated with stroke.

RECENT FINDINGS

Calcific debris from degenerating aortic and mitral valves may embolize to the cerebral vasculature causing small- or large-vessel ischemia. Thrombus which may be adherent to calcified valvular structures or left-sided cardiac tumors may also embolize resulting in stroke. Tumors themselves, most commonly myxomas and papillary fibroelastomas, may fragment and travel to the cerebral vasculature. Despite this broad differential, many types of valve diseases are highly comorbid with atrial fibrillation and vascular atheromatous disease. Thus, a high index of suspicion for more common causes of stroke is needed, especially given that treatment for valvular lesions typically involves cardiac surgery whereas secondary prevention of stroke due to occult atrial fibrillation is readily accomplished with anticoagulation.

Atherosclerosis Calcification: Focus on Lipoproteins

Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of lipids in the vessel wall, leading to the formation of an atheroma and eventually to the development of vascular calcification (VC). Lipoproteins play a central role in the development of atherosclerosis and VC. Both low- and very low-density lipoproteins (LDL and VLDL) and lipoprotein (a) (Lp(a)) stimulate, while high-density lipoproteins (HDL) reduce VC. Apolipoproteins, the protein component of lipoproteins, influence the development of VC in multiple ways. Apolipoprotein AI (apoAI), the main protein component of HDL, has anti-calcific properties, while apoB and apoCIII, the main protein components of LDL and VLDL, respectively, promote VC. The role of lipoproteins in VC is also related to their metabolism and modifications. Oxidized LDL (OxLDL) are more pro-calcific than native LDL. Oxidation also converts HDL from anti- to pro-calcific. Additionally, enzymes such as autotaxin (ATX) and proprotein convertase subtilisin/kexin type 9 (PCSK9), involved in lipoprotein metabolism, have a stimulatory role in VC. In summary, a better understanding of the mechanisms by which lipoproteins and apolipoproteins contribute to VC will be crucial in the development of effective preventive and therapeutic strategies for VC and its associated cardiovascular disease.

Lipoprotein(a) and Its Autoantibodies in Association with Calcific Aortic Valve Stenosis

Aortic valve stenosis is the most common valvular heart disease in the Western world. Lipoprotein(a) (Lp(a)) is an independent risk factor of coronary heart disease (CHD) and calcific aortic valve stenosis (CAVS). The aim of this study was to assess the role of Lp(a) and its autoantibodies [autoAbs] in CAVS in patients with and without CHD. We included 250 patients (mean age 69 ± 3 years, males 42%) and divided them into three groups. There were two groups of patients with CAVS depending on the presence (group 1) or absence of CHD (group 2). The control group included the patients without CHD or CAVS. According to logistic regression analysis, levels of Lp(a), IgM autoAbs to oxidized Lp(a) (oxLp(a)), and age were independent predictors of CAVS. A concomitant increase in Lp(a) level (≥30 mg/dL) and a decrease in IgM autoAbs concentration (<9.9 lab. Units) are associated with CAVS with an odds ratio (OR) of 6.4, p < 0.01, and with CAVS and CHD with an OR of 17.3, p < 0.001. IgM autoantibodies to oxLp(a) are associated with calcific aortic valve stenosis regardless of Lp(a) concentration and other risk factors. Higher Lp(a) and lower IgM autoantibodies to oxLp(a) levels are associated with a much higher risk of calcific aortic valve stenosis.

Pathophysiology, emerging techniques for the assessment and novel treatment of aortic stenosis

Our perspectives on aortic stenosis (AS) are changing. Evolving from the traditional thought of a passive degenerative disease, developing a greater understanding of the condition's mechanistic underpinning has shifted the paradigm to an active disease process. This advancement from the 'wear and tear' model is a result of the growing economic and health burden of AS, particularly within industrialised countries, prompting further research. The pathophysiology of calcific AS (CAS) is complex, yet can be characterised similarly to that of atherosclerosis. Progressive remodelling involves lipid-protein complexes, with lipoprotein(a) being of particular interest for diagnostics and potential future treatment options.There is an unmet clinical need for asymptomatic patient management; no pharmacotherapies are proven to slow progression and intervention timing varies. Novel approaches are developing to address this through: (1) screening with circulating biomarkers; (2) development of drugs to slow disease progression and (3) early valve intervention guided by medical imaging. Existing biomarkers (troponin and brain natriuretic peptide) are non-specific, but cost-effective predictors of ventricular dysfunction. In addition, their integration with cardiovascular MRI can provide accurate risk stratification, aiding aortic valve replacement decision making. Currently, invasive intervention is the only treatment for AS. In comparison, the development of lipoprotein(a) lowering therapies could provide an alternative; slowing progression of CAS, preventing left ventricular dysfunction and reducing reliance on surgical intervention.The landscape of AS management is rapidly evolving. This review outlines current understanding of the pathophysiology of AS, its management and future perspectives for the condition's assessment and treatment.

Calcific aortic valve disease: mechanisms, prevention and treatment

Calcific aortic valve disease (CAVD) is the most common disorder affecting heart valves and is characterized by thickening, fibrosis and mineralization of the aortic valve leaflets. Analyses of surgically explanted aortic valve leaflets have shown that dystrophic mineralization and osteogenic transition of valve interstitial cells co-occur with neovascularization, microhaemorrhage and abnormal production of extracellular matrix. Age and congenital bicuspid aortic valve morphology are important and unalterable risk factors for CAVD, whereas additional risk is conferred by elevated blood pressure and plasma lipoprotein(a) levels and the presence of obesity and diabetes mellitus, which are modifiable factors. Genetic and molecular studies have identified that the NOTCH, WNT-β-catenin and myocardin signalling pathways are involved in the control and commitment of valvular cells to a fibrocalcific lineage. Complex interactions between valve endothelial and interstitial cells and immune cells promote the remodelling of aortic valve leaflets and the development of CAVD. Although no medical therapy is effective for reducing or preventing the progression of CAVD, studies have started to identify actionable targets.

Tissue and Serum Biomarkers in Degenerative Aortic Stenosis-Insights into Pathogenesis, Prevention and Therapy

Background and Aim. Degenerative Aortic Stenosis (DAS) is a common disease that causes substantial morbidity and mortality worldwide, especially in the older population. Our aim was to further investigate novel serum and tissue biomarkers to elucidate biological processes involved in this entity. Material and Methods. We evaluated the expression of six biomarkers significantly involved in cardiovascular pathology, i.e., irisin, periostin, osteoglycin, interleukin 18, high mobility group box 1 and proprotein convertase subtilisin/kexin type 9 in the serum at the protein level, and in the tissue at both the protein and mRNA levels of patients with AS (N = 60). Five normal valves obtained after transplantation from hearts of patients with idiopathic dilated cardiomyopathy were also studied. Serum measurements were also performed in 22 individuals without valvular disease who served as controls (C). Results. Higher levels of all factors were found in DAS patients’ serum than in normal C. IHC and PCR mRNA tissue analysis showed the presence of all biomarkers in the aortic valve cusps with DAS, but no trace of PCR mRNA was found in the five transplantation valves. Moreover, periostin serum levels correlated significantly with IHC and mRNA tissue levels in AS patients. Conclusion. We showed that six widely prevalent biomarkers affecting the atherosclerotic process were also involved in DAS, suggesting a strong osteogenic and pro-inflammatory profile, indicating that aortic valve calcification is a multifactorial biological process.

Lipoprotein(a): Cardiovascular Disease, Aortic Stenosis and New Therapeutic Option

Atherosclerosis is a chronic and progressive inflammatory process beginning early in life with late clinical manifestation. This slow pathological trend underlines the importance to early identify high-risk patients and to treat intensively risk factors to prevent the onset and/or the progression of atherosclerotic lesions. In addition to the common Cardiovascular (CV) risk factors, new markers able to increase the risk of CV disease have been identified. Among them, high levels of Lipoprotein(a)-Lp(a)-lead to very high risk of future CV diseases; this relationship has been well demonstrated in epidemiological, mendelian randomization and genome-wide association studies as well as in meta-analyses. Recently, new aspects have been identified, such as its association with aortic stenosis. Although till recent years it has been considered an unmodifiable risk factor, specific drugs have been developed with a strong efficacy in reducing the circulating levels of Lp(a) and their capacity to reduce subsequent CV events is under testing in ongoing trials. In this paper we will review all these aspects: from the synthesis, clearance and measurement of Lp(a), through the findings that examine its association with CV diseases and aortic stenosis to the new therapeutic options that will be available in the next years.

Aortic Stenosis: New Insights in Diagnosis, Treatment, and Prevention

Aortic stenosis (AS) is one of the most common valvular heart diseases and the number of patients with AS is expected to increase globally as the older population is growing fast. Since the majority of patients are elderly, AS is no longer a simple valvular heart disease of left ventricular outflow obstruction but is accompanied by other cardiac and comorbid conditions. Because of the significant variations of the disease, identifying patients at high risk and even earlier detection of patients with AS before developing symptomatic severe AS is becoming increasingly important. With the proven of efficacy and safety of transcatheter aortic valve replacement (TAVR) in the severe AS population, there is a growing interest in applying TAVR in those with less than severe AS. A medical therapy to reduce or prevent the progression in AS is actively investigated by several randomized control trials. In this review, we will summarize the most recent findings in AS and discuss potential future management strategies of patients with AS.

PCSK9 Inhibition: From Current Advances to Evolving Future

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secretory serine protease synthesized primarily by the liver. It mainly promotes the degradation of low-density lipoprotein receptor (LDL-R) by binding LDL-R, reducing low-density lipoprotein cholesterol (LDL-C) clearance. In addition to regulating LDL-R, PCSK9 inhibitors can also bind Toll-like receptors (TLRs), scavenger receptor B (SR-B/CD36), low-density lipoprotein receptor-related protein 1 (LRP1), apolipoprotein E receptor-2 (ApoER2) and very-low-density lipoprotein receptor (VLDL-R) reducing the lipoprotein concentration and slowing thrombosis. In addition to cardiovascular diseases, PCSK9 is also used in pancreatic cancer, sepsis, and Parkinson’s disease. Currently marketed PCSK9 inhibitors include alirocumab, evolocumab, and inclisiran, as well as small molecules, nucleic acid drugs, and vaccines under development. This review systematically summarized the application, preclinical studies, safety, mechanism of action, and latest research progress of PCSK9 inhibitors, aiming to provide ideas for the drug research and development and the clinical application of PCSK9 in cardiovascular diseases and expand its application in other diseases.

Contribution of Oxidative Stress (OS) in Calcific Aortic Valve Disease (CAVD): From Pathophysiology to Therapeutic Targets

Calcific aortic valve disease (CAVD) is a major cause of cardiovascular mortality and morbidity, with increased prevalence and incidence. The underlying mechanisms behind CAVD are complex, and are mainly illustrated by inflammation, mechanical stress (which induces prolonged aortic valve endothelial dysfunction), increased oxidative stress (OS) (which trigger fibrosis), and calcification of valve leaflets. To date, besides aortic valve replacement, there are no specific pharmacological treatments for CAVD. In this review, we describe the mechanisms behind aortic valvular disease, the involvement of OS as a fundamental element in disease progression with predilection in AS, and its two most frequent etiologies (calcific aortic valve disease and bicuspid aortic valve); moreover, we highlight the potential of OS as a future therapeutic target.

The mechanistic pathways of oxidative stress in aortic stenosis and clinical implications

Despite the elucidation of the pathways behind the development of aortic stenosis (AS), there remains no effective medical treatment to slow or reverse its progress. Instead, the gold standard of care in severe or symptomatic AS is replacement of the aortic valve. Oxidative stress is implicated, both directly as well as indirectly, in lipid infiltration, inflammation and fibro-calcification, all of which are key processes underlying the pathophysiology of degenerative AS. This culminates in the breakdown of the extracellular matrix, differentiation of the valvular interstitial cells into an osteogenic phenotype, and finally, calcium deposition as well as thickening of the aortic valve. Oxidative stress is thus a promising and potential therapeutic target for the treatment of AS. Several studies focusing on the mitigation of oxidative stress in the context of AS have shown some success in animal and in vitro models, however similar benefits have yet to be seen in clinical trials. Statin therapy, once thought to be the key to the treatment of AS, has yielded disappointing results, however newer lipid lowering therapies may hold some promise. Other potential therapies, such as manipulation of microRNAs, blockade of the renin-angiotensin-aldosterone system and the use of dipeptidylpeptidase-4 inhibitors will also be reviewed.

Aortic stenosis in homozygous familial hypercholesterolaemia: a paradigm shift over a century

AIMS

Homozygous familial hypercholesterolaemia (HoFH) is an orphan disease defined by extreme elevations in low-density lipoprotein cholesterol, cutaneous xanthomas, and pre-mature atherosclerotic cardiovascular disease. Survival has more than doubled over the past three decades. Aortic stenosis (AS) [supravalvular aortic stenosis (SVAS) or valvular aortic stenosis (VAS)] is commonly encountered. There are no medical treatments available and complex high-risk surgeries represent the only available option in severe cases. A systematic review was performed to summarize the current evidence on AS in HoFH and to determine whether pharmacological treatment (statins) have had an impact on clinical presentation, phenotype and clinical course over the past nine decades (PROSPERO CRD42021250565).

METHODS AND RESULTS

MEDLINE, Embase Classic + Embase, Cochrane Central Register of Controlled Trials, PubMed, AfricaWide, and Scopus were searched from inception to 10 November 2021. Searches identified 381 publications, of which 19 were retained; they were cross-sectional or retrospective studies. Separately, 108 individual case reports were described. Within the 424 HoFH cases, AS was identified in 57% of patients in the pre-statin era vs. 35% in patients reported more recently (>2000, long-term statin period). With an increase in longevity due to statins and lipoprotein apheresis, a change in the proportion of patients with SVAS and VAS with a SVAS:VAS ratio of 47:53 and 10:90 for HoFH patients not on statin and on long-term statin, respectively, was noted.

CONCLUSION

These data suggest that SVAS and VAS are frequent in HoFH and that the phenotype has shifted towards calcific VAS as statins and lipoprotein apheresis improve survival in these patients.

Implication of Lipids in Calcified Aortic Valve Pathogenesis: Why Did Statins Fail?

Calcific Aortic Valve Disease (CAVD) is a fibrocalcific disease. Lipoproteins and oxidized phospholipids play a substantial role in CAVD; the level of Lp(a) has been shown to accelerate the progression of valve calcification. Indeed, oxidized phospholipids carried by Lp(a) into the aortic valve stimulate endothelial dysfunction and promote inflammation. Inflammation and growth factors actively promote the synthesis of the extracellular matrix (ECM) and trigger an osteogenic program. The accumulation of ECM proteins promotes lipid adhesion to valve tissue, which could initiate the osteogenic program in interstitial valve cells. Statin treatment has been shown to have the ability to diminish the death rate in subjects with atherosclerotic impediments by decreasing the serum LDL cholesterol levels. However, the use of HMG-CoA inhibitors (statins) as cholesterol-lowering therapy did not significantly reduce the progression or the severity of aortic valve calcification. However, new clinical trials targeting Lp(a) or PCSK9 are showing promising results in reducing the severity of aortic stenosis. In this review, we discuss the implication of lipids in aortic valve calcification and the current findings on the effect of lipid-lowering therapy in aortic stenosis.

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

Importance

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

Observations

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

Conclusions and Relevance

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

Effect of Alirocumab on Coronary Calcification in Patients With Coronary Artery Disease

Background

Proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors have been documented with significantly reduction in LDL cholesterol levels and cardiovascular events. However, evidence regarding the impact of PCSK9 inhibitors on coronary calcification is limited.

Methods

Eligible patients with intermediate coronary lesions and elevated LDL cholesterol values were randomized to either alirocumab 75 mg Q2W plus statin (atorvastatin 20 mg/day or rosuvastatin 10 mg/day) therapy or standard statin therapy. Calcium score based on coronary computed tomographic angiography at baseline and follow up were compared.

Results

Compared with baseline levels, LDL cholesterol were significantly decreased in both groups, while the absolute reduction of LDL cholesterol levels were higher in patients treated with alirocumab (1.69 ± 0.52 vs. 0.92 ± 0.60, P < 0.0001). Additionally, patients in alirocumab group demonstrated a significant reduction of Lp(a) levels, whereas it was not observed in the standard statin group. Notably, greater increases in the percentage changes of CAC score (10.6% [6.3–23.3] vs. 2.9% [−6.7–8.3]; P < 0.0001) were observed in the statin group compared to the alirocumab group. Consistently, CAC progression was significantly lower in the alirocumab group than in the standard statin group (0.6 ± 2.2% vs. 2.7 ± 2.3%; P = 0.002).

Conclusions

Study indicated that administration of the PCSK9 inhibitors to statins produced significantly lower rate of CAC progression in patients with coronary artery disease. Further studies with CAC progression and their clinical outcomes are needed.

Trial Registration

ClinicalTrials.gov, Identifier: NCT04851769.

Plasma Lipoprotein(a) measured in routine clinical care and the association with incident calcified aortic valve stenosis during a 14-year observational period

BACKGROUND AND AIMS

Lipoprotein(a) [Lp(a)] is a causal cardiovascular risk factor recommended to be measured at least once in a lifetime. We aimed to establish the association between routinely measured Lp(a) levels and the development of incident calcified aortic valve stenosis (CAVS).

METHODS

This retrospective registry based observational study includes all individuals who had their Lp(a) measured in clinical routine between 2003 and 2017 at Karolinska University Laboratory, Stockholm. Data on pre-existing medical conditions, pharmacological treatment and outcomes were retrieved from national patient registries.

RESULTS

The study comprised 23,298 individuals of which 489 received a CAVS diagnosis during the study period. The CAVS group (71 ± 11 years, 62% males) had a larger cardiovascular burden than the group without CAVS (55 ± 17 years and 48% males). Individuals with CAVS had higher Lp(a) 90th percentile (117 mg/dL or 249 nmol/L) than those without (89 mg/dL or 179 nmol/L) (p < 0.001), a difference seen in both sexes. The incident rates of CAVS per 10,000 person-years was 22.3 for individuals at >90th Lp(a) percentile compared to 12.8 for the 0th - 50th percentiles (p < 0.001). Sex and age adjusted hazard ratios for development of incident CAVS was 1.53 (95% CI 1.08-2.15; p = 0.016) and for surgical or endovascular intervention for CAVS 1.42 (95% CI 0.73-2.79; p = 0.304) for individuals at Lp(a) > 90th percentile compared to the 0th - 50th percentile.

CONCLUSIONS

Lp(a) measured in the clinical routine is higher in individuals with CAVS. An Lp(a) level above >90th percentile is associated with the development of incident CAVS during a 14-year observational period.