Aortic valve perivascular adipose tissue computed tomography attenuation in patients with aortic stenosis

OBJECTIVE

Aortic stenosis (AS) shares pathophysiological similarities with atherosclerosis including active inflammation. CT attenuation of perivascular adipose tissue provides a measure of vascular inflammation that is linked to prognosis and has the potential to be applied to the aortic valve. We investigated perivascular adipose tissue attenuation around the aortic valve in patients with AS.

METHODS

CT attenuation was measured in the perivascular adipose tissue extending 3 mm radially and 10 mm longitudinally around the aortic valve in patients with and without AS. Associations between perivascular adipose tissue attenuation and AS disease severity, activity and progression were investigated.

RESULTS

Perivascular adipose tissue attenuation around the aortic valve demonstrated good intraobserver and interobserver repeatability (interobserver: intraclass correlation coefficient 0.977 (95% CI: 0.94, 0.99)) but was similar between patients with AS (n=120) and control subjects (n=80) (-62.4 (-68.7, -56.5) Hounsfield units (HU) vs -61.2 (-65.3, -55.6) HU, p=0.099). There were no differences between perivascular adipose tissue attenuation in patients with mild (-60.2 (-66.9, -55.1) HU), moderate (-62.8 (-69.6, -56.80) HU) or severe (-62.3 (-69.3, -55.4) HU) AS (all p>0.05), and perivascular adipose tissue attenuation did not demonstrate an association with AS severity as assessed by echocardiography or CT calcium scoring, nor with disease activity assessed by 18F-sodium fluoride positron emission tomography. Moreover, there was no association between baseline aortic valve perivascular adipose tissue attenuation and subsequent AS progression (annualised change in peak velocity: r=0.072, p=0.458). Similar results were found using five other image analysis methods.

CONCLUSIONS

CT-derived aortic valve perivascular adipose tissue attenuation is not associated with AS disease severity, activity or progression suggesting that it has no value in the investigation and management of patients with AS.

The Role of Endoplasmic Reticulum Stress in Calcific Aortic Valve Disease

Calcific aortic valve disease (CAVD), which is involved in osteogenic reprogramming of valvular interstitial cells, is the most common form of valve disease. It still lacks effective pharmacologic intervention, as its cellular biological mechanisms remain unclear. Congenital abnormality (bicuspid valve) and older age are considered to be the most powerful risk factors for CAVD. Aortic valve sclerosis (AVS) and calcific aortic stenosis (CAS), 2 subclinical forms of CAVD, represent 2 distinct stages of aortic valve calcification. During the AVS stage, the disease is characterised by endothelial activation/damage, inflammatory response, and lipid infiltration accompanied by microcalcification. The CAS stage is dominated by calcification, resulting in valvular dysfunction and severe obstruction to cardiac outflow, which is life threatening if surgery is not performed in time. Endoplasmic reticulum (ER) stress, a state in which conditions disrupting ER homeostasis cause an accumulation of unfolded and misfolded proteins in the ER lumen, has been shown to promote osteogenic differentiation and aortic valve calcification. Therefore, identifying targets or drugs for suppressing ER stress may be a novel approach for CAVD treatment.

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.

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.

Molecular Mechanisms Underlying the Progression of Aortic Valve Stenosis: Bioinformatic Analysis of Signal Pathways and Hub Genes

The calcification of the aortic valve causes increased leaflet stiffness and leads to the development and progression of stenotic aortic valve disease. However, the molecular and cellular mechanisms underlying stenotic calcification remain poorly understood. Herein, we examined the gene expression associated with valve calcification and the progression of calcific aortic valve stenosis. We downloaded two publicly available gene expression profiles (GSE83453 and GSE51472) from NCBI-Gene Expression Omnibus database for the combined analysis of samples from human aortic stenosis and normal aortic valve tissue. After identifying the differentially expressed genes (DEGs) using the GEO2R online tool, we performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses. We also analyzed the protein-protein interactions (PPIs) of the DEGs using the NetworkAnalyst online tool. We identified 4603 upregulated and 6272 downregulated DEGs, which were enriched in the positive regulation of cell adhesion, leukocyte-mediated immunity, response to hormones, cytokine signaling in the immune system, lymphocyte activation, and growth hormone receptor signaling. PPI network analysis identified 10 hub genes: VCAM1, FHL2, RUNX1, TNFSF10, PLAU, SPOCK1, CD74, SIPA1L2, TRIB1, and CXCL12. Through bioinformatic analysis, we identified potential biomarkers and therapeutic targets for aortic stenosis, providing a theoretical basis for future studies.

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.

Aortic Stenosis Progression: A Systematic Review and Meta-Analysis

BACKGROUND

Aortic valve stenosis is a progressive disorder with variable progression rates. The factors affecting aortic stenosis (AS) progression remain largely unknown.

OBJECTIVES

This systematic review and meta-analysis sought to determine AS progression rates and to assess the impact of baseline AS severity and sex on disease progression.

METHODS

The authors searched Medline, Embase, and the Cochrane Central Register of Controlled Trials from inception to July 1, 2020, for prospective studies evaluating the progression of AS with the use of echocardiography (mean gradient [MG], peak velocity [PV], peak gradient [PG], or aortic valve area [AVA]) or computed tomography (calcium score [AVC]). Random-effects meta-analysis was performed to evaluate the rate of AS progression for each parameter stratified by baseline severity, and meta-regression was performed to determine the impact of baseline severity and of sex on AS progression rate.

RESULTS

A total of 24 studies including 5,450 patients (40% female) met inclusion criteria. The pooled annualized progression of MG was +4.10 mm Hg (95% CI: 2.80-5.41 mm Hg), AVA -0.08 cm² (95% CI: 0.06-0.10 cm²), PV +0.19 m/s (95% CI: 0.13-0.24 m/s), PG +7.86 mm Hg (95% CI: 4.98-10.75 mm Hg), and AVC +158.5 AU (95% CI: 55.0-261.9 AU). Increasing baseline severity of AS was predictive of higher rates of progression for MG (P < 0.001), PV (P = 0.001), and AVC (P < 0.001), but not AVA (P = 0.34) or PG (P = 0.21). Only 4 studies reported AS progression stratified by sex, with only PV and AVC having 3 studies to perform a meta-analysis. No difference between sex was observed for PV (P = 0.397) or AVC (P = 0.572), but the level of confidence was low.

CONCLUSIONS

This study provides progression rates for both hemodynamic and anatomic parameters of AS and shows that increasing hemodynamic and anatomic baseline severity is associated with faster AS progression. More studies are needed to determine if sex differences affect AS progression. (Aortic Valve Stenosis Progression Rate: A Systematic Review and Meta-Analysis; CRD42021207726).

Lipoprotein(a): Its Association with Calcific Aortic Valve Stenosis, the Emerging RNA-Related Treatments and the Hope for a New Era in “Treating” Aortic Valve Calcification

The treatment of patients with aortic valve calcification (AVC) and calcific aortic valve stenosis (CAVS) remains challenging as, until today, all non-invasive interventions have proven fruitless in preventing the disease’s onset and progression. Despite the similarities in the pathogenesis of AVC and atherosclerosis, statins failed to show a favorable effect in preventing AVC progression. The recognition of lipoprotein(a) [Lp(a)] as a strong and potentially modifiable risk factor for the development and, perhaps, the progression of AVC and CAVS and the evolution of novel agents leading in a robust Lp(a) reduction, have rekindled hope for a promising future in the treatment of those patients. Lp(a) seems to promote AVC via a ‘three hit’ mechanism including lipid deposition, inflammation and autotaxin transportation. All of these lead to valve interstitial cells transition into osteoblast-like cells and, thus, to parenchymal calcification. Currently available lipid-lowering therapies have shown a neutral or mild effect on Lp(a), which was proven insufficient to contribute to clinical benefits. The short-term safety and the efficacy of the emerging agents in reducing Lp(a) have been proven; nevertheless, their effect on cardiovascular risk is currently under investigation in phase 3 clinical trials. A positive result of these trials will probably be the spark to test the hypothesis of the modification of AVC’s natural history with the novel Lp(a)-lowering agents.

Exploration and validation of the influence of angiogenesis-related factors in aortic valve calcification

Over the years, bioinformatics tools have been used to identify functional genes. In the present study, bioinformatics analyses were conducted to explore the underlying molecular mechanisms of angiogenic factors in calcific aortic valve disease (CAVD). The raw gene expression profiles were from datasets GSE153555, GSE83453, and GSE51472, and the angiogenesis-related gene set was from the Gene Set Enrichment Analysis database (GSEA). In this study, R was used to screen for differentially expressed genes (DEGs) and co-expressed genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genome (KEGG) Pathway enrichment analysis were performed on DEGs and validated in clinical samples. DEGs in CAVD were significantly enriched in numerous immune response pathways, inflammatory response pathways and angiogenesis-related pathways. Nine highly expressed angiogenesis-related genes were identified, of which secretogranin II (SCG2) was the most critical gene. MiRNA and transcription factors (TFs) networks were established centered on five DEGs, and zinc finger E-box binding homeobox 1 (ZEB1) was the most important transcription factor, verified by PCR, immunohistochemical staining and western blotting experiments. Overall, this study identified key genes and TFs that may be involved in the pathogenesis of CAVD and may have promising applications in the treatment of CAVD.

Circulating Progenitor Cells Are Associated With Bioprosthetic Aortic Valve Deterioration: A Preliminary Study

Background Mechanisms underlying bioprosthetic valve deterioration are multifactorial and incompletely elucidated. Reparative circulating progenitor cells, and conversely calcification-associated osteocalcin expressing circulating progenitor cells, have been linked to native aortic valve deterioration. However, their role in bioprosthetic valve deterioration remains elusive. This study sought to evaluate the contribution of different subpopulations of circulating progenitor cells in bioprosthetic valve deterioration. Methods and Results This single-center prospective study enrolled 121 patients who had peripheral blood mononuclear cells isolated before bioprosthetic aortic valve replacement and had an echocardiographic follow-up ≥2 years after the procedure. Using flow cytometry, fresh peripheral blood mononuclear cells were analyzed for the surface markers CD34, CD133, and osteocalcin. Bioprosthetic valve deterioration was evaluated by hemodynamic valve deterioration (HVD) using echocardiography, which was defined as an elevated mean transprosthetic gradient ≥30 mm Hg or at least moderate intraprosthetic regurgitation. Sixteen patients (13.2%) developed HVD during follow-up for a median of 5.9 years. Patients with HVD showed significantly lower levels of reparative CD34⁺CD133⁺ cells and higher levels of osteocalcin-positive cells than those without HVD (CD34⁺CD133⁺ cells: 125 [80, 210] versus 270 [130, 420], P=0.002; osteocalcin-positive cells: 3060 [523, 5528] versus 670 [180, 1930], P=0.005 respectively). Decreased level of CD34⁺CD133⁺ cells was a significant predictor of HVD (hazard ratio, 0.995 [95% CI, 0.990%-0.999%]). Conclusions Circulating levels of CD34⁺CD133⁺ cells and osteocalcin-positive cells were significantly associated with the subsequent occurrence of HVD in patients undergoing bioprosthetic aortic valve replacement. Circulating progenitor cells might play a vital role in the mechanism, risk stratification, and a potential therapeutic target for patients with bioprosthetic valve deterioration.

Molecular Imaging of Valvular Diseases and Cardiac Device Infection

The use of positron emission tomography imaging with 18F-fluorodeoxyglucose in the diagnostic workup of patients with suspected prosthetic valve endocarditis and cardiac device infection (implantable electronic device and left ventricular assist device) is gaining momentum in clinical practice. However, in the absence of prospective randomized trials, guideline recommendations about 18F-fluorodeoxyglucose positron emission tomography in this setting are currently largely based on expert opinion. Measurement of aortic valve microcalcification occurring as a healing response to valvular inflammation using 18F-sodium fluoride positron emission tomography represents another promising clinical approach, which is associated with both the risk of native valve stenosis progression and bioprosthetic valve degeneration in research trials. In this review, we consider the role of molecular imaging in cardiac valvular diseases, including aortic stenosis and valvular endocarditis, as well as cardiac device infections.

The Associations of Aortic Valve Sclerosis, Aortic Annular Increased Reflectivity, and Mitral Annular Calcification with Subsequent Aortic Stenosis in Older Individuals: Findings from the Cardiovascular Health Study

BACKGROUND

Although aortic valve sclerosis (AVS) is well described as preceding aortic stenosis (AS), the associations of AS with antecedent mitral annular calcification (MAC) and aortic annular increased reflectivity (AAIR) have not been characterized. In a population-based prospective study, the authors evaluated whether MAC, AAIR, and AVS are associated with the risk for incident AS.

METHODS

Among participants of the Cardiovascular Health Study free of AS at the 1994-1995 visit, the presence of MAC, AAIR, AVS, and the combination of all three was evaluated in 3,041 participants. Cox proportional-hazards regression was used to assess the association between the presence of calcification and the incidence of moderate or severe AS in three nested models adjusting for factors associated with atherosclerosis and inflammation both relevant to the pathogenesis of AS.

RESULTS

Over a median follow-up period of 11.5 years (interquartile range, 6.7-17.0 years), 110 cases of incident moderate or severe AS were ascertained. Strong positive associations with incident moderate or severe AS were found for all calcification sites after adjustment for the main model covariates: AAIR (hazard ratio [HR], 2.90; 95% CI, 1.95-4.32; P < .0005), AVS (HR, 2.20; 95% CI, 1.44-3.37; P < .0005), MAC (HR, 1.67; 95% CI, 1.14-2.45; P = .008), and the combination of all three (HR, 2.50; 95% CI, 1.65-3.78; P < .0005). In a secondary analysis, the risk for AS increased with the number of sites at which calcification was present.

CONCLUSIONS

In a large cohort of community-dwelling elderly individuals, there were strong associations between each of AAIR, AVS, MAC, and the combination of the three and incident moderate or severe AS. The novel finding that AAIR had a particularly strong association with incident AS, even after adjusting for other calcification sites, suggests its value in identifying individuals at risk for AS and potential inclusion in routine assessment by transthoracic echocardiography.

Toll-like receptor-3 contributes to the development of aortic valve stenosis

Aortic valve stenosis (AS) development is driven by distinct molecular and cellular mechanisms which include inflammatory pathways. Toll-like-receptor-3 (TLR3) is a lysosomal pattern-recognition receptor that binds double-stranded RNA and promotes pro-inflammatory cellular responses. In recent years, TLR3 has emerged as a major regulator of vascular inflammation. The exact role of TLR3 in the development of AS has not been investigated. Isolated human valvular interstitial cells (VICs) were stimulated with the TLR3-agonist polyIC and the resulting pro-inflammatory and pro-osteogenic response measured. Severe AS was induced in wildtype- and TLR3^-/- mice via mechanical injury of the aortic valve with a coronary springwire. TLR3 activation was achieved by polyIC injection every 24 h after wire injury, while TLR3 inhibition was realized using Compound 4a (C4a) every 48 h after surgery. Endothelial mesenchymal transition (EndoMT) of human valvular endothelial cells (VECs) was assessed after polyIC stimulation. Stimulation of human VICs with polyIC promoted a strong inflammatory and pro-osteogenic reaction. Similarly, injection of polyIC marginally increased AS development in mice after wire injury. AS induction was significantly decreased in TLR3^-/- mice, confirming the role of endogenous TLR3 ligands in AS pathology. Pharmacological inhibition of TLR3 with C4a not only prevented the upregulation of inflammatory cytokines and osteogenic markers in VICs, and EndoMT in VECs, but also significantly abolished the development of AS in vivo. Endogenous TLR3 activation significantly contributes to AS development in mice. Pharmacological inhibition of TLR3 with C4a prevented AS formation. Therefore, targeting TLR3 may be a viable treatment option.

Trans-Aortic Flow Turbulence and Aortic Valve Inflammation: A Pilot Study Using Blood Speckle Imaging and 18F-Sodium Fluoride Positron Emission Tomography/Computed Tomography in Patients With Moderate Aortic Stenosis

BACKGROUND

¹⁸F-sodium fluoride positron emission tomography/computed tomography (¹⁸F-NaF PET/CT) has been proven to be useful in identification of microcalcifications, which are stimulated by inflammation. Blood speckle imaging (BSI) is a new imaging technology used for tracking the flow of blood cells using transesophageal echocardiography (TEE). We evaluated the relationship between turbulent flow identified by BSI and inflammatory activity of the aortic valve (AV) as indicated by the ¹⁸F-NaF uptake index in moderate aortic stenosis (AS) patients.

METHODS

This study enrolled 18 moderate AS patients diagnosed within the past 6 months. BSI within the aortic root was acquired using long-axis view TEE. The duration of laminar flow and the turbulent flow area ratio were calculated by BSI to demonstrate the degree of turbulence. The maximum and mean standardized uptake values (SUVmax, SUVmean) and the total microcalcification burden (TMB) as measured by ¹⁸F-NaF PET/CT were used to demonstrate the degree of inflammatory activity in the AV region.

RESULTS

The mean SUVmean, SUVmax, and TMB were 1.90 ± 0.79, 2.60 ± 0.98, and 4.20 ± 2.18 mL, respectively. The mean laminar flow period and the turbulent area ratio were 116.1 ± 61.5 msec and 0.48 ± 0.32. The correlation between SUVmax and turbulent flow area ratio showed the most positive and statistically significant correlation, with a Pearson's correlation coefficient (R²) of 0.658 and a p-value of 0.014.

CONCLUSIONS

The high degree of trans-aortic turbulence measured by BSI was correlated with severe AV inflammation.

Quantifying microcalcification activity in the thoracic aorta

BACKGROUND

Standard methods for quantifying positron emission tomography (PET) uptake in the aorta are time consuming and may not reflect overall vessel activity. We describe aortic microcalcification activity (AMA), a novel method for quantifying 18F-sodium fluoride (18F-NaF) uptake in the thoracic aorta.

METHODS

Twenty patients underwent two hybrid 18F-NaF PET and computed tomography (CT) scans of the thoracic aorta less than three weeks apart. AMA, as well as maximum (TBRmax) and mean (TBRmean) tissue to background ratios, were calculated by two trained operators. Intra-observer repeatability, inter-observer repeatability and scan-rescan reproducibility were assessed. Each 18F-NaF quantification method was compared to validated cardiovascular risk scores.

RESULTS

Aortic microcalcification activity demonstrated excellent intra-observer (intraclass correlation coefficient 0.98) and inter-observer (intraclass correlation coefficient 0.97) repeatability with very good scan-rescan reproducibility (intraclass correlation coefficient 0.86) which were similar to previously described TBRmean and TBRmax methods. AMA analysis was much quicker to perform than standard TBR assessment (3.4min versus 15.1min, P<0.0001). AMA was correlated with Framingham stroke risk scores and Framingham risk score for hard cononary heart disease.

CONCLUSIONS

AMA is a simple, rapid and reproducible method of quantifying global 18F-NaF uptake across the ascending aorta and aortic arch that correlates with cardiovascular risk scores.

Latest Advances in Multimodality Imaging of Aortic Stenosis

Aortic stenosis is a common condition associated with major morbidity, mortality, and health-care costs. Nevertheless, we currently lack any effective medical therapies that can treat or prevent disease development or progression. Modern advances in echocardiography and CT have helped improve the assessment of aortic stenosis severity and monitoring of disease progression, whereas cardiac MRI informs on myocardial health and the development of fibrosis. In a series of recent studies, 18F-NaF PET/CT has been shown to assess valvular disease activity and progression, providing mechanistic insights that can inform potential novel therapeutic approaches. This review will examine the latest advances in the imaging of aortic stenosis and bioprosthetic valve degeneration and explore how these techniques can assist patient management and potentially accelerate novel therapeutic developments.

Bioinformatics and Machine Learning Methods to Identify FN1 as a Novel Biomarker of Aortic Valve Calcification

Aim

The purpose of this study was to identify potential diagnostic markers for aortic valve calcification (AVC) and to investigate the function of immune cell infiltration in this disease.

Methods

The AVC data sets were obtained from the Gene Expression Omnibus. The identification of differentially expressed genes (DEGs) and the performance of functional correlation analysis were carried out using the R software. To explore hub genes related to AVC, a protein–protein interaction network was created. Diagnostic markers for AVC were then screened and verified using the least absolute shrinkage and selection operator, logistic regression, support vector machine-recursive feature elimination algorithms, and hub genes. The infiltration of immune cells into AVC tissues was evaluated using CIBERSORT, and the correlation between diagnostic markers and infiltrating immune cells was analyzed. Finally, the Connectivity Map database was used to forecast the candidate small molecule drugs that might be used as prospective medications to treat AVC.

Results

A total of 337 DEGs were screened. The DEGs that were discovered were mostly related with atherosclerosis and arteriosclerotic cardiovascular disease, according to the analyses. Gene sets involved in the chemokine signaling pathway and cytokine–cytokine receptor interaction were differently active in AVC compared with control. As the diagnostic marker for AVC, fibronectin 1 (FN1) (area the curve = 0.958) was discovered. Immune cell infiltration analysis revealed that the AVC process may be mediated by naïve B cells, memory B cells, plasma cells, activated natural killer cells, monocytes, and macrophages M0. Additionally, FN1 expression was associated with memory B cells, M0 macrophages, activated mast cells, resting mast cells, monocytes, and activated natural killer cells. AVC may be reversed with the use of yohimbic acid, the most promising small molecule discovered so far.

Conclusion

FN1 can be used as a diagnostic marker for AVC. It has been shown that immune cell infiltration is important in the onset and progression of AVC, which may benefit in the improvement of AVC diagnosis and treatment.

The role of antibody responses against glycans in bioprosthetic heart valve calcification and deterioration

Bioprosthetic heart valves (BHVs) are commonly used to replace severely diseased heart valves but their susceptibility to structural valve degeneration (SVD) limits their use in young patients. We hypothesized that antibodies against immunogenic glycans present on BHVs, particularly antibodies against the xenoantigens galactose-α1,3-galactose (αGal) and N-glycolylneuraminic acid (Neu5Gc), could mediate their deterioration through calcification. We established a large longitudinal prospective international cohort of patients (n = 1668, 34 ± 43 months of follow-up (0.1–182); 4,998 blood samples) to investigate the hemodynamics and immune responses associated with BHVs up to 15 years after aortic valve replacement. Early signs of SVD appeared in <5% of BHV recipients within 2 years. The levels of both anti-αGal and anti-Neu5Gc IgGs significantly increased one month after BHV implantation. The levels of these IgGs declined thereafter but anti-αGal IgG levels declined significantly faster in control patients compared to BHV recipients. Neu5Gc, anti-Neu5Gc IgG and complement deposition were found in calcified BHVs at much higher levels than in calcified native aortic valves. Moreover, in mice, anti-Neu5Gc antibodies were unable to promote calcium deposition on subcutaneously implanted BHV tissue engineered to lack αGal and Neu5Gc antigens. These results indicate that BHVs manufactured using donor tissues deficient in αGal and Neu5Gc could be less prone to immune-mediated deterioration and have improved durability.

In a large cohort of patients who underwent aortic valve replacement, antibody responses to glycans present in bioprosthetic heart valves, notably galactose-α1,3-galactose and N-glycolylneuraminic acid, were implicated in valve calcification and deterioration.

The Complex Interplay of Inflammation, Metabolism, Epigenetics, and Sex in Calcific Disease of the Aortic Valve

Calcification of the aortic valve is one of the most rapidly increasing pathologies in the aging population worldwide. Traditionally associated to cardiovascular risk conditions, this pathology is still relatively unaddressed on a molecular/cellular standpoint and there are no available treatments to retard its progression unless valve substitution. In this review, we will describe some of the most involved inflammatory players, the metabolic changes that may be responsible of epigenetic modifications and the gender-related differences in the onset of the disease. A better understanding of these aspects and their integration into a unique pathophysiology context is relevant to improve current therapies and patients management.

Exploring potential genes and pathways related to calcific aortic valve disease

Calcific aortic valve disease (CAVD) is currently the most prevalent valvular disease. However, the pathological mechanism of CAVD has not yet been fully elucidated, and no drugs can delay or halt the progression of CAVD. This study aimed to screen for potential biomarkers and pathways of CAVD through bioinformatics analysis. The identification of differentially expressed genes (DEGs) between calcific aortic valves and the control group was performed based on four microarray datasets: GSE12644, GSE51472, GSE77287 and GSE83453. Gene Ontology and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway enrichment analysis were conducted. Furthermore, the protein-protein interaction network, and microRNA-target interaction was performed, and hub genes were obtained by using twelve cytoHubba algorithms. As a result, 327 DEGs were identified, including 206 up-regulated and 121 down-regulated genes. KEGG analysis showed that these DEGs were mainly enriched in the PI3K-AKT signaling pathway, ECM-receptor interaction, cytokine-cytokine receptor interaction, and chemokine signaling pathway etc. Moreover, we identified 19 hub genes: CXCL8, CXCL12, CSF1R, HCK, PLEK, CCL5, TLR8, VCAM1, CCR1, CCR7, FPR1, TYROBP, CX3CR1, KIT, PPBP, SPP1, SYK, TLR7, and VWF. And multiple potential miRNAs, including miR-141, miR-34a, miR-155, and miR-486, were identified. And western blot was performed to validate the expression level of hub genes. In conclusion, this study identified several promising biomarkers and pathways for CAVD, which may provide novel molecular markers for diagnosis and targeted therapy.

Metformin alleviates the calcification of aortic valve interstitial cells through activating the PI3K/AKT pathway in an AMPK dependent way

BACKGROUND

Calcific aortic valve disease (CAVD) is the most prevalent valvular disease worldwide. However, no effective treatment could delay or prevent the progression of the disease due to the poor understanding of its pathological mechanism. Many studies showed that metformin exerted beneficial effects on multiple cardiovascular diseases by mediating multiple proteins such as AMPK, NF-κB, and AKT. This study aims to verify whether metformin can inhibit aortic calcification through the PI3K/AKT signaling pathway.

METHODS

We first analyzed four microarray datasets to screen differentially expressed genes (DEGs) and signaling pathways related to CAVD. Then aortic valve samples were used to verify selected genes and pathways through immunohistochemistry (IHC) and western blot (WB) assays. Aortic valve interstitial cells (AVICs) were isolated from non-calcific aortic valves and then cultured with phosphate medium (PM) with or without metformin to verify whether metformin can inhibit the osteogenic differentiation and calcification of AVICs. Finally, we used inhibitors and siRNA targeting AMPK, NF-κB, and AKT to study the mechanism of metformin.

RESULTS

We screened 227 DEGs; NF-κB and PI3K/AKT signaling pathways were implicated in the pathological mechanism of CAVD. IHC and WB experiments showed decreased AMPK and AKT and increased Bax in calcific aortic valves. PM treatment significantly reduced AMPK and PI3K/AKT signaling pathways, promoted Bax/Bcl2 ratio, and induced AVICs calcification. Metformin treatment ameliorated AVICs calcification and apoptosis by activating the PI3K/AKT signaling pathway. AMPK activation and NF-κB inhibition could inhibit AVICs calcification induced by PM treatment; however, AMPK and AKT inhibition reversed the protective effect of metformin.

CONCLUSIONS

This study, for the first time, demonstrates that metformin can inhibit AVICs in vitro calcification by activating the PI3K/AKT signaling pathway; this suggests that metformin may provide a potential target for the treatment of CAVD. And the PI3K/AKT signaling pathway emerges as an important regulatory axis in the pathological mechanism of CAVD.

Comparative Analysis of the Kinetic Behavior of Systemic Inflammatory Markers in Patients with Depressed versus Preserved Left Ventricular Function Undergoing Transcatheter Aortic Valve Implantation

BACKGROUND

Prior studies have proven the safety and efficacy of transcatheter aortic valve implantation (TAVI) in patients with reduced left ventricular (LV) function. This study's aim was to investigate periprocedural inflammatory responses after TAVI.

METHODS

Patients with severe symptomatic aortic stenosis and reduced LV function who underwent transfemoral TAVI were enrolled. A paired-matched analysis (1:2 ratio) was performed using patients with preserved LV function. Whole white blood cells (WBC) and subpopulation dynamics as well as the neutrophil to lymphocyte ratio (NLR) were evaluated at different times.

RESULTS

A total of 156 patients were enrolled, including 52 patients with LVEF < 40% 35.00 [30.00, 39.25] and 104 with LVEF > 50% 55.00 [53.75, 60.0], p < 0.001. Baseline NLR in the reduced LV function group was significantly higher compared to the preserved LV function group, 2.85 [2.07, 4.78] vs. 3.90 [2.67, 5.26], p < 0.04. After a six-month follow-up, the inflammatory profile was found to be similar in the two groups, NLR 2.94 [2.01, 388] vs. 3.30 [2.06, 5.35], p = 0.288. No significant mortality differences between the two groups were observed in the long-term outcome.

CONCLUSIONS

TAVI for severe symptomatic aortic stenosis, with reduced LV function, was associated with an improvement in the inflammatory profile that may account for some of the observable benefits of the procedure in this subset of patients.

Bone mineral density and long-term progression of aortic valve and mitral annular calcification: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND AND AIMS

Bone and mineral metabolism has been implicated in the pathophysiology of cardiac valve calcification. Whether bone demineralization, a common aging-related disorder, promotes calcific valve disease remains uncertain. We tested the hypothesis that low bone mineral density (BMD) is associated with greater incidence/progression of cardiac valve calcification in the Multi-Ethnic Study of Atherosclerosis.

METHODS

Using linear mixed-effects models, we related baseline measurement of BMD of the thoracic vertebrae by computed tomography (CT) in 6768 participants to serial CT assessments of aortic valve calcification (AVC) and mitral annular calcification (MAC) obtained over a >10-year period.

RESULTS

After multivariable adjustment, lower BMD (per SD decrement) was associated with accelerated increase in AVC over time in women (0.76 [95% CI 0.42,1.09] Agatston -units [AU]/year) and men (1.41 [95% CI 0.48,2.33] AU/year), as well as for MAC in women (3.22 [95% CI 1.16,5.28] AU/year) and men (3.59 [95% CI 2.09,5.09] AU/year). Significant effect modification was observed, with more pronounced BMD-related acceleration of AVC and MAC progression in older or white participants of one or both sexes, as well as by estimated glomerular filtration rate, though the latter differed by sex for AVC and MAC.

CONCLUSIONS

In this multi-ethnic cohort, low thoracic BMD was significantly, but modestly, associated with increased AVC and MAC progression. This suggests that altered bone mineral metabolism does not have a major impact on calcific valve disease in the general population, but the possibility of a more meaningful influence in higher-risk individuals with osteoporosis will require further investigation.

Interaction of SOX5 with SOX9 promotes warfarin-induced aortic valve interstitial cell calcification by repressing transcriptional activation of LRP6

Calcific aortic valve disease (CAVD) is an important health burden due to its increasing prevalence and lack of available approaches. Osteogenic transdifferentiation of aortic valve interstitial cells (AVICs) contributes to valve calcification. SRY-related HMG-box transcription factor 5 (SOX5) is essential for cartilage development. Whether SOX5 is involved in AVIC calcification has not been determined. This study aimed to explore the role of SOX5 in warfarin-induced AVIC calcification. Immunostaining showed decreased SOX5 in human calcific AV and warfarin induced mouse calcific AV tissues compared with human noncalcific AV and control mouse AV tissues. In calcific human AVICs (hAVICs) and porcine AVICS (pAVICs), both knockdown and overexpression of SOX5 inhibited calcium deposition and osteogenic marker gene expression. Protein expression assays and ChIP assays showed that overexpression of SOX5 led to increased recruitment of SOX5 to the SOX9 promoter and resulted in increased mRNA and protein expression of SOX9. Coimmunoprecipitation and immunofluorescence showed that SOX5 binds to SOX9 with its HMG domain in nucleus. Blue Native PAGE showed overexpression of SOX5 led to multimeric complex formation of SOX5 and resulted in decreased binding of SOX5 to SOX9 similar to the results of knockdown of SOX5. Further ChIP and western blotting assays showed that both knockdown and overexpression of SOX5 resulted in SOX9 initiating transcription of anti-calcific gene LRP6 in warfarin-treated pAVICs. Knockdown of LRP6 rescues the anti-calcification effect of SOX5 overexpression. We found that both loss and gain of function of SOX5 lead to the same phenotype: decreased warfarin induced calcification. The stoichiometry of SOX5 is crucial for cooperation with SOX9, SOX9 nuclear localization and subsequent binding of SOX9 to LRP6 promoter. These results suggest that SOX5 is a potential target for the development of anti-calcification therapy.

Diagnosis and Management of Aortic Valve Stenosis: The Role of Non-Invasive Imaging

Aortic stenosis is the most common heart valve disease necessitating surgical or percutaneous intervention. Imaging has a central role for the initial diagnostic work-up, the follow-up and the selection of the optimal timing and type of intervention. Referral for aortic valve replacement is currently driven by the severity and by the presence of aortic stenosis-related symptoms or signs of left ventricular systolic dysfunction. This review aims to provide an update of the imaging techniques and seeks to highlight a practical approach to help clinical decision making.

Sodium fluoride in cardiovascular disorders: A systematic review

BACKGROUND

18-Fluorine sodium fluoride is a well-known radiotracer used for bone metastasis diagnosis. Its uptake correlation with cardiovascular (CV) risk was primarily suggested in oncological patients. Moreover, as a specific marker of microcalcification, it seems to correlate with CV disease progression and plaque instability.

METHODS AND RESULTS

Our purpose was to systematically review clinical studies that characterized the use of this marker in CV conditions. In atherosclerosis, most studies report a positive correlation with the burden of CV risk factors and vascular calcification. A higher uptake was found in culprit plaques/rupture sites in coronary and carotid arteries and it was also linked to high-risk features in histology and intravascular imaging analysis of the plaques. In aortic stenosis, this tracer displayed an increasing uptake with disease severity.

CONCLUSIONS

Sodium fluoride positron emission tomography is a promising non-invasive technique to identify high-risk plaques, which sets ground to a potential use of this tracer in evaluating atherosclerotic disease progression and degenerative changes in aortic valve stenosis. Nevertheless, there is a need for further prospective evidence that demonstrates this technique's value in predicting clinical events, adjusting treatment strategies, and improving patient outcomes.

Clinical implications of 18F-sodium fluoride uptake in subclinical aortic valve calcification: Its relation to coronary atherosclerosis and its predictive value

BACKGROUND

Uptake of 18F-sodium fluoride (18F-NaF) on positron emission tomography (PET) reflects active calcification. Application of this technique in the early phase of aortic valve calcification (AVC) is of clinical interest. We investigated clinical implications of 18F-NaF uptake in subclinical AVC evaluated simultaneously with coronary atherosclerosis, and the utility of 18F-NaF uptake in predicting AVC progression.

METHODS

We studied 25 patients with subclinical AVC and coronary plaques detected on computed tomography (CT) who underwent 18F-NaF PET/CT. AVC score, volume, mean density, and the presence of high-risk coronary plaque were evaluated on CT in each patient. Focal 18F-NaF uptake in AVC and in coronary plaques was quantified with the maximum tissue-to-background ratio (TBRmax).

RESULTS

There were positive correlations between AVC TBRmax (A-TBRmax) and AVC parameters on CT. The 14 patients with high-risk coronary plaque had significantly higher A-TBRmax than those without such plaque (1.60 ± 0.18 vs 1.42 ± 0.13, respectively; P = 0.012). A-TBRmax positively correlated with maximum TBRmax of coronary plaque per patient (r = 0.55, P = 0.0043). In the 11 patients who underwent follow-up CT scan, A-TBRmax positively correlated with subsequent increase in AVC score (r = 0.74, P = 0.0091).

CONCLUSION

Our 18F-NaF PET- and CT-based data indicate relationships between calcification activity in subclinical AVC and characteristics of coronary atherosclerosis. 18F-NaF PET may provide new information regarding molecular conditions and future progression of subclinical AVC.

Advanced cardiovascular multimodal imaging and aortic stenosis

Aortic valve stenosis has become the most common valvular heart disease on account of aging population and increasing life expectancy. Echocardiography is the primary diagnosis tool for this, but it still has many flaws. Therefore, advanced cardiovascular multimodal imaging techniques are continuously being developed in order to overcome these limitations. Cardiac magnetic resonance imaging (CMR) allows a comprehensive morphological and functional evaluation of the aortic valve and provides important data for the diagnosis and risk stratification in patients with aortic stenosis. CMR can functionally assess the aortic flow using two-dimensional and time-resolved three-dimensional velocity-encoded phase-contrast techniques. Furthermore, by late gadolinium enhancement and T1-mapping, CMR can reveal the presence of both irreversible replacement and diffuse interstitial myocardial fibrosis. Moreover, its role in guiding aortic valve replacement procedures is beginning to take shape. Recent studies have rendered the importance of active and passive biomechanics in risk stratification and prognosis prediction in patients with aortic stenosis, but more work is required is just in its infancy, but data are promising. In addition, cardiac computed tomography is particularly useful for the diagnosis of aortic valve stenosis, and in preprocedural evaluation of the aorta, while positron emission tomography can be also used to assess valvular inflammation and active calcification. The purpose of this review is to provide a comprehensive overview of current available data regarding advanced cardiovascular multimodal imaging in aortic stenosis.

Multimodality imaging in valvular heart disease: how to use state-of-the-art technology in daily practice

Our understanding of the complexities of valvular heart disease (VHD) has evolved in recent years, primarily because of the increased use of multimodality imaging (MMI). Whilst echocardiography remains the primary imaging technique, the contemporary evaluation of patients with VHD requires comprehensive analysis of the mechanism of valvular dysfunction, accurate quantification of severity, and active exclusion extravalvular consequences. Furthermore, advances in surgical and percutaneous therapies have driven the need for meticulous multimodality imaging to aid in patient and procedural selection. Fundamental decision-making regarding whom, when, and how to treat patients with VHD has become more complex. There has been rapid technological advancement in MMI; many techniques are now available in routine clinical practice, and their integration into has the potential to truly individualize management strategies. This review provides an overview of the current evidence for the use of MMI in VHD, and how various techniques within each modality can be used practically to answer clinical conundrums.

Dihydrotanshinone I inhibits aortic valve interstitial cell calcification via the SMAD1/5/8/NF-κB/ERK pathway

OBJECTIVES

In calcific aortic valve disease (CAVD), the valve interstitial cells (VIC) osteogenic phenotype changes can lead to thickening and calcification of the valve leaflets，eventually lead to restricted valve movement and life-threatening. This study aims to investigate the effect and mechanism of dihydrotanshinone I (DHI) on osteogenic medium (OM) induced osteogenic phenotypic transition of porcine valve interstitial cells (PVICs), which can provide theoretical and scientific basis for clinical intervention in CAVD.

METHODS AND RESULTS

Immunohistochemical methods were used to detect the expression of osteogenic indicators Runx2, OPN and inflammation indicators IL-1β and p-NF-κB in valve specimens of CAVD patients(N = 3) and normal controls(N = 1). PVICs stimulated by osteoblastic medium (OM) were treated with or without DHI. CCK8, ALP and Alizarin Red S staining were used to detect cell growth and calcification, respectively. The results showed that under the treated with DHI, compared with OM, the formation of calcium nodules was reduced, and the expression of calcification-related markers Runx2 and OPN were down-regulated, which quantified by qRT-PCR and western blot. In addition, on the basis of OM induction, DHI also inhibited the phosphorylation of the NF-κB/ERK1/2 and SMAD1/5/8 signaling pathway.

CONCLUSION

DHI (10 μM) treatment can reverse the osteogenic phenotypic transition of PVICs induced by osteogenic medium, and the mechanism may be related to NF-κB、ERK 1/2 and Smad1/5/8 pathways.

Detecting native and bioprosthetic aortic valve disease using 18F-sodium fluoride: Clinical implications

Calcific aortic valve disease is the most common valvular disease and confers significant morbidity and mortality. There are currently no medical therapies that successfully halt or reverse the disease progression, making surgical replacement the only treatment currently available. The majority of patients will receive a bioprosthetic valve, which themselves are prone to degeneration and may also need replaced, adding to the already substantial healthcare burden of aortic stenosis. Echocardiography and computed tomography can identify late-stage manifestations of the disease process affecting native and bioprosthetic aortic valves but cannot detect or quantify early molecular changes. 18F-fluoride positron emission tomography, on the other hand, can non-invasively and sensitively assess disease activity in the valves. The current review outlines the pivotal role this novel molecular imaging technique has played in improving our understanding of native and bioprosthetic aortic valve disease, as well as providing insights into its feasibility as an important future research and clinical tool.

The Usefulness of [18F]F-Fluorodeoxyglucose and [18F]F-Sodium Fluoride Positron Emission Tomography Imaging in the Assessment of Early-Stage Aortic Valve Degeneration after Transcatheter Aortic Valve Implantation (TAVI)-Protocol Description and Preliminary Results

Transcatheter aortic valve implantation (TAVI) is now a well-established treatment for severe aortic stenosis. As the number of procedures and indications increase, the age of patients decreases. However, their durability and factors accelerating the process of degeneration are not well-known. The aim of the study was to verify the possibility of using [¹⁸F]F-sodium fluoride ([¹⁸F]F-NaF) and [¹⁸F]F-fluorodeoxyglucose ([¹⁸F]F-FDG) positron emission tomography/computed tomography (PET/CT) in assessing the intensity of TAVI valve degenerative processes. In 73 TAVI patients, transthoracic echocardiography (TTE) at initial (before TAVI), baseline (after TAVI), and during follow-up, as well as transesophageal echocardiography (TEE) and PET/CT, were performed using [¹⁸F]F-NaF and [¹⁸F]F-FDG at the six-month follow-up (FU) visit as a part of a two-year FU period. The morphology of TAVI valve leaflets were assessed in TEE, transvalvular gradients and effective orifice area (EOA) in TTE. Calcium scores and PET tracer activity were counted. We assessed the relationship between [¹⁸F]F-NaF and [¹⁸F]F-FDG PET/CT uptake at the 6 = month FU with selected indices e.g.,: transvalvular gradient, valve type, EOA and insufficiency grade at following time points after the TAVI procedure. We present the preliminary PET/CT ([¹⁸F]F-NaF, [¹⁸F]F-FDG) results at the six-month follow-up period as are part of an ongoing study, which will last two years FU. We enrolled 73 TAVI patients with the mean age of 82.49 ± 7.11 years. A significant decrease in transvalvular gradient and increase of effective orifice area and left ventricle ejection fraction were observed. At six months, FU valve thrombosis was diagnosed in four patients, while 7.6% of patients refused planned controls due to the COVID-19 pandemic. We noticed significant correlations between valve types, EOA and transaortic valve gradients, as well as [¹⁸F]F-NaF and [¹⁸F]F-FDG uptake in PET/CT. PET/CT imaging with the use of [¹⁸F]F-FDG and [¹⁸F]F-NaF is intended to be feasible, and it practically allows the standardized uptake value (SUV) to differentiate the area containing the TAVI leaflets from the SUV directly adjacent to the ring calcifications and the calcified native leaflets. This could become the seed for future detection and evaluation capabilities regarding the progression of even early degenerative lesions to the TAVI valve, expressed as local leaflet inflammation and microcalcifications.

Computed tomography aortic valve calcium scoring for the assessment of aortic stenosis progression

OBJECTIVE

CT quantification of aortic valve calcification (CT-AVC) is useful in the assessment of aortic stenosis severity. Our objective was to assess its ability to track aortic stenosis progression compared with echocardiography.

METHODS

Subjects were recruited in two cohorts: (1) a reproducibility cohort where patients underwent repeat CT-AVC or echocardiography within 4 weeks and (2) a disease progression cohort where patients underwent annual CT-AVC and/or echocardiography. Cohen's d-statistic (d) was computed from the ratio of annualised progression and measurement repeatability and used to estimate group sizes required to detect annualised changes in CT-AVC and echocardiography.

RESULTS

A total of 33 (age 71±8) and 81 participants (age 72±8) were recruited to the reproducibility and progression cohorts, respectively. Ten CT scans (16%) were excluded from the progression cohort due to non-diagnostic image quality. Scan-rescan reproducibility was excellent for CT-AVC (limits of agreement -12% to 10 %, intraclass correlation (ICC) 0.99), peak velocity (-7% to +17%; ICC 0.92) mean gradient (-25% to 27%, ICC 0.96) and dimensionless index (-11% to +15%; ICC 0.98). Repeat measurements of aortic valve area (AVA) were less reliable (-44% to +28%, ICC 0.85).CT-AVC progressed by 152 (65-375) AU/year. For echocardiography, the median annual change in peak velocity was 0.1 (0.0-0.3) m/s/year, mean gradient 2 (0-4) mm Hg/year and AVA -0.1 (-0.2-0.0) cm2/year. Cohen's d-statistic was more than double for CT-AVC (d=3.12) than each echocardiographic measure (peak velocity d=0.71 ; mean gradient d=0.66; AVA d=0.59, dimensionless index d=1.41).

CONCLUSION

CT-AVC is reproducible and demonstrates larger increases over time normalised to measurement repeatability compared with echocardiographic measures.

Oscillatory fluid-induced mechanobiology in heart valves with parallels to the vasculature

Forces generated by blood flow are known to contribute to cardiovascular development and remodeling. These hemodynamic forces induce molecular signals that are communicated from the endothelium to various cell types. The cardiovascular system consists of the heart and the vasculature, and together they deliver nutrients throughout the body. While heart valves and blood vessels experience different environmental forces and differ in morphology as well as cell types, they both can undergo pathological remodeling and become susceptible to calcification. In addition, while the plaque morphology is similar in valvular and vascular diseases, therapeutic targets available for the latter condition are not effective in the management of heart valve calcification. Therefore, research in valvular and vascular pathologies and treatments have largely remained independent. Nonetheless, understanding the similarities and differences in development, calcific/fibrous pathologies and healthy remodeling events between the valvular and vascular systems can help us better identify future treatments for both types of tissues, particularly for heart valve pathologies which have been understudied in comparison to arterial diseases.

Melatonin ameliorates aortic valve calcification via the regulation of circular RNA CircRIC3/miR-204-5p/DPP4 signaling in valvular interstitial cells

Calcific aortic valve disease (CAVD) is highly prevalent with marked morbidity and mortality rates and a lack of pharmaceutical treatment options because its mechanisms are unknown. Melatonin is reported to exert atheroprotective effects. However, whether melatonin protects against aortic valve calcification, a disease whose pathogenesis shares many similarities to that of atherosclerosis, and the underlying molecular mechanisms remain unknown. In this study, we found that the intragastric administration of melatonin for 24 weeks markedly ameliorated aortic valve calcification in high cholesterol diet (HCD)-treated ApoE^-/- mice, as evidenced by reduced thickness and calcium deposition in the aortic valve leaflets, improved echocardiographic parameters (decreased transvalvular peak jet velocity and increased aortic valve area), and decreased osteogenic differentiation marker (Runx2, osteocalcin, and osterix) expression in the aortic valves. Consistent with these in vivo data, we also confirmed the suppression of in vitro calcification by melatonin in hVICs. Mechanistically, melatonin reduced the level of CircRIC3, a procalcification circular RNA, which functions by acting as a miR-204-5p sponge to positively regulate the expression of the procalcification gene dipeptidyl peptidase-4 (DPP4). Furthermore, CircRIC3 overexpression abolished the inhibitory effects of melatonin on hVIC osteogenic differentiation. Taken together, our results suggest that melatonin ameliorates aortic valve calcification via the regulation of CircRIC3/miR-204-5p/DPP4 signaling in hVICs; therefore, melatonin medication might be considered a novel pharmaceutical strategy for CAVD treatment.

Aortic valve stenosis-multimodality assessment with PET/CT and PET/MRI

Aortic valve disease is the most common form of heart valve disease in developed countries and a growing healthcare burden with an ageing population. Transthoracic and transoesophageal echocardiography remains central to the diagnosis and surveillance of patients with aortic stenosis, providing gold standard assessments of valve haemodynamics and myocardial performance. However, other multimodality imaging techniques are being explored for the assessment of aortic stenosis, including combined PET/CT and PET/MR. Both approaches provide unique information with respect to disease activity in the valve alongside more conventional anatomic assessments of the valve and myocardium in this condition. This review investigates the emerging use of PET/CT and PET/MR to assess patients with aortic stenosis, examining how the complementary data provided by each modality may be used for research applications and potentially in future clinical practice.

AntagomiR-29b inhibits vascular and valvular calcification and improves heart function in rats

We aimed to investigate the role of the miR‐29b and its effect on TGF‐β3 pathway in vascular and valvular calcification in a rat model of calcific aortic valve diseases (CAVD). A rat model of CAVD was established by administration of warfarin plus vitamin K. The expression levels of miR‐29b, osteogenic markers and other genes were determined by qRT‐PCR, Western blot and/or immunofluorescence and immunohistochemistry. The calcium content and alkaline phosphatase (ALP) activity were measured. The calcium content, ALP activity and osteogenic markers levels in calcified aorta and aortic valve were augmented compared to controls. The expression of miR‐29b, p‐Smad3, and Wnt3 and β‐catenin was significantly up‐regulated, whereas TGF‐β3 was markedly down‐regulated. However, compared with the CAVD model group, the calcium content and ALP activity in rats treated with antagomiR‐29b were significantly decreased, and antagomiR‐29b administration reversed the effects of CAVD model on the expression of miR‐29b and osteogenic markers. Inhibition of miR‐29b in CAVD rats prevented from vascular and valvular calcification and induced TGF‐β3 expression, suggesting that the miR‐29b/TGF‐β3 axis may play a regulatory role in the pathogenesis of vascular and valvular calcification and could play a significant role in the treatment of CAVD and other cardiovascular diseases.

Biomarkers Associated With Aortic Valve Calcification: Should We Focus on Sex Specific Processes?

Objective

Circulating biomarkers are useful in detection and monitoring of cardiovascular diseases. However, their role in aortic valve disease is unclear. Mechanisms are rapidly elucidated and sex differences are suggested to be involved. Therefore, we sought to identify biomarkers involved in aortic valve calcification (AVC) stratified by sex.

Methods

Blood samples of 34 patients with AVC (without further overt cardiovascular disease, including absence of hemodynamic consequences of valvular calcification) were compared with 136 patients without AVC. AVC was determined using computed tomography calcium scoring. Circulating biomarkers were quantified using a novel antibody-based method (Olink Proseek Multiplex Cardiovascular Panel I) and 92 biomarkers were compared between patients with and without AVC.

Results

In the overall population, Interleukin-1 Receptor Antagonist and pappalysin-1 were associated with increased and decreased odds of having AVC. These differences were driven by the male population [IL1RA: OR 2.79 (1.16-6.70), p = 0.022; PAPPA: OR 0.30 (0.11-0.84), p = 0.021]. Furthermore, TNF-related activation-induced cytokine (TRANCE) and fibroblast growth factor-23 were associated decreased odds of having AVC, and monocyte chemotactic protein-1 was associated with increased odds of having AVC [TRANCE: OR 0.32 (0.12-0.80), p = 0.015; FGF23: OR 0.41 (0.170-0.991), p = 0.048; MCP1: OR 2.64 (1.02-6.81), p = 0.045]. In contrast, galanin peptides and ST2 were associated with increased odds of having AVC in females [GAL: OR 12.38 (1.31-116.7), p = 0.028; ST2: OR13.64 (1.21-153.33), p = 0.034].

Conclusion

In this exploratory study, we identified biomarkers involved in inflammation, fibrosis and calcification which may be associated with having AVC. Biomarkers involved in fibrosis may show higher expression in females, whilst biomarkers involved in inflammation and calcification could associate with AVC in males.

18F-Sodium Fluoride (18F-NaF) for Imaging Microcalcification Activity in the Cardiovascular System

Accumulating preclinical and clinical evidence suggests that calcification is one of the body's primary responses to injury and a key pathological feature of cardiovascular disease. Calcification activity can now be imaged using 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) in combination with either computed tomography or magnetic resonance. These techniques allow visualization of calcification activity and, therefore, provide different information to the established macroscopic calcium imaged with computed tomography. Indeed, 18F-NaF PET has been used to investigate a wide range of valvular conditions, including aortic stenosis, mitral annular calcification, and bioprosthetic valve disease, as well as vascular conditions, including abdominal aortic aneurysm disease, coronary, and carotid atherosclerosis, peripheral vascular disease, and erectile dysfunction. In this brief review, we will focus on how 18F-NaF PET has improved our pathophysiological understanding of cardiovascular calcification and how it can be used as a marker of vascular calcification, providing a useful tool that can be utilized in clinical trials investigating the prediction of both disease progression and clinical events. Finally, we will discuss how 18F-NaF might be employed clinically to improve patient assessment and to guide decision-making.

Analytical quantification of aortic valve 18F-sodium fluoride PET uptake

BACKGROUND

Challenges to cardiac PET-CT include patient motion, prolonged image acquisition and a reduction of counts due to gating. We compared two analytical tools, FusionQuant and OsiriX, for quantification of gated cardiac 18F-sodium fluoride (18F-fluoride) PET-CT imaging.

METHODS

Twenty-seven patients with aortic stenosis were included, 15 of whom underwent repeated imaging 4 weeks apart. Agreement between analytical tools and scan-rescan reproducibility was determined using the Bland-Altman method and Lin's concordance correlation coefficients (CCC).

RESULTS

Image analysis was faster with FusionQuant [median time (IQR) 7:10 (6:40-8:20) minutes] compared with OsiriX [8:30 (8:00-10:10) minutes, p = .002]. Agreement of uptake measurements between programs was excellent, CCC = 0.972 (95% CI 0.949-0.995) for mean tissue-to-background ratio (TBRmean) and 0.981 (95% CI 0.965-0.997) for maximum tissue-to-background ratio (TBRmax). Mean noise decreased from 11.7% in the diastolic gate to 6.7% in motion-corrected images (p = .002); SNR increased from 25.41 to 41.13 (p = .0001). Aortic valve scan-rescan reproducibility for TBRmax was improved with FusionQuant using motion correction compared to OsiriX (error ± 36% vs ± 13%, p < .001) while reproducibility for TBRmean was similar (± 10% vs ± 8% p = .252).

CONCLUSION

18F-fluoride PET quantification with FusionQuant and OsiriX is comparable. FusionQuant with motion correction offers advantages with respect to analysis time and reproducibility of TBRmax values.

Imaging aortic valve calcification: significance, approach and implications

Aortic stenosis is the most prevalent valvular heart disease worldwide, and rates are increasing with the growing and more elderly population. Although the precise mechanisms that underpin aortic valve stenosis are incompletely understood, pathological valvular calcification has emerged as a key instigator in mediating the biomechanical stiffening that can lead to symptoms, the need for aortic valve replacement, and death if left untreated. Here, we review the currently understood processes leading to aortic valve calcification, summarise the contemporary imaging assessments of valve calcification, and highlight how these might improve patient care and accelerate our pathological understanding and the development of an effective medical therapy.

Aortic valve microcalcification and cardiovascular risk: an exploratory study using sodium fluoride in high cardiovascular risk patients

18F-sodium fluoride (18F-NaF) has been used to access aortic stenosis in clinical research setting. It is known that its uptake is related with microcalcification. The purpose of this study was to assess the relationship between 18F-NaF uptake by the aortic valve and cardiovascular risk. Twenty-five patients with risk factors for cardiovascular disease, without known cardiovascular disease or aortic stenosis underwent PET-CT with 18F-NaF. Cardiovascular risk was assessed through the ASCVD (Atherosclerotic Cardiovascular Disease) risk calculator. Aortic valve 18F-NaF (AoVCUL) uptake was evaluated through the corrected uptake per lesion (CUL = max SUV - mean blood-pool SUV). Calcium score was obtained through cardiac CT. The patients present a mean age of 63.90 ± 8.60 years and 56% males. The mean ASCVD was of 28.76 ± 18.96 (M 25, IQR 38.50). The mean aortic valve calcium score (AoVCaSc) was of 53.24 ± 164.38 (M 6; IQR 29.75) and the AoVCUL was of 0.50 ± 0.10 (M 0.52, IQR 0.15). The patients were classified according to the ASCVD: patients with a risk greater or equal than the 50th percentile of the ASCVD risk and patients with a risk lower than the 50th percentile. The AoVCUL was evaluated in both groups: AoVCUL = 0.56 ± 0.10 vs 0.42 ± 0.15, p = 0.02; AoVCaSc was of 0 in 11 patients (44%) and those with an ASCVD greater or equal than the 50th percentile had a mean AoVCaSc of 8.00 ± 13.80, and those with an ASCVD risk lower than the 50th percentile had a mean AoVCaSc of 95.00 ± 223.45; p = 0.09. In this study microcalcification, evaluated through 18F-NaF on PET-CT, was related with cardiovascular risk. Although the score of calcium seems to be higher in higher cardiovascular risk patients, no significant difference was found between groups.

Association Between Homocysteine and Vascular Calcification Incidence, Prevalence, and Progression in the MESA Cohort

Background While elevated homocysteine has been associated with calcification in several studies, its importance as a cardiovascular risk factor remains unclear. This study examines the relationship between homocysteine and vascular and valve calcification in the MESA (Multi-ethnic Study of Atherosclerosis) cohort. Methods and Results MESA participants with baseline homocysteine measurements and cardiac computed tomography scans were included (N=6789). Baseline and follow-up assessment of vascular (coronary artery [CAC], descending thoracic aorta [DTAC]) and valve (aortic valve [AVC], mitral annular [MAC]) calcification was performed. Prevalence ratio/relative risk regression was used to assess the relationship of homocysteine with prevalent and incident calcification, and multivariable logistic regression was used to assess associations between homocysteine and calcification progression. Elevated homocysteine was associated with greater relative risk of prevalent and incident CAC and incident DTAC. We also identified a strong association between elevated homocysteine and CAC and DTAC progression. Elevated homocysteine was found to confer a >2-fold increased risk of severe CAC progression (defined as ΔCAC ≥100/year) and an ≈1.5-fold increased risk for severe DTAC progression (defined as ΔDTAC ≥100/year). Conclusions To our knowledge, this is the first study demonstrating an association between elevated homocysteine and both incidence and progression of coronary and extra-coronary vascular calcification. Our findings suggest a potential role for elevated homocysteine as a risk factor for severe vascular calcification progression. Future studies are warranted to further assess the utility of homocysteine as a biomarker for vascular calcification incidence and progression. Clinical Trial Registration https://www.clinicaltrials.gov/. Unique identifier: NCT00005487.

Disease Activity in Mitral Annular Calcification

BACKGROUND

Mitral annular calcification (MAC) is associated with cardiovascular events and mitral valve dysfunction. However, the underlying pathophysiology remains incompletely understood. In this prospective longitudinal study, we used a multimodality approach including positron emission tomography, computed tomography, and echocardiography to investigate the pathophysiology of MAC and assess factors associated with disease activity and progression.

METHODS

A total of 104 patients (age 72±8 years, 30% women) with calcific aortic valve disease, therefore predisposed to MAC, underwent ¹⁸F-sodium fluoride (calcification activity) and ¹⁸F-Fluorodeoxyglucose (inflammation activity) positron emission tomography, computed tomography calcium scoring, and echocardiography. Sixty patients underwent repeat computed tomography and echocardiography after 2 years.

RESULTS

MAC (mitral annular calcium score >0) was present in 35 (33.7%) patients who had increased ¹⁸F-fluoride (tissue-to-background ratio, 2.32 [95% CI, 1.81-3.27] versus 1.30 [1.22-1.49]; P<0.001) and ¹⁸F-Fluorodeoxyglucose activity (tissue-to-background ratio, 1.44 [1.37-1.58] versus 1.17 [1.12-1.24]; P<0.001) compared with patients without MAC. MAC activity (¹⁸F-fluoride uptake) was closely associated with the local calcium score and ¹⁸F-Fluorodeoxyglucose uptake, as well as female sex and renal function. Similarly, MAC progression was closely associated with local factors, in particular, baseline MAC. Traditional cardiovascular risk factors and calcification activity in bone or remote atherosclerotic areas were not associated with disease activity nor progression.

CONCLUSIONS

MAC is characterized by increased local calcification activity and inflammation. Baseline MAC burden was associated with disease activity and the rate of subsequent progression. This suggests a self-perpetuating cycle of calcification and inflammation that may be the target of future therapeutic interventions.

Identification of key genes and pathways in calcific aortic valve disease by bioinformatics analysis

Background

Calcific aortic valve disease (CAVD) is the most common type of valvular heart disease in the elderly. This study is aimed to explore molecular mechanism of CAVD via bioinformatics analysis.

Methods

The gene expression profiles of GSE51472 (including 5 normal aortic valve and 5 calcified aortic valve) and GSE83453 (including 8 normal aortic valve and 19 calcified aortic valve) were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened using the MetaDE package in R software. Functional and pathway enrichment analysis were performed based on Gene ontology (GO) and KEGG pathway database. Then, STRING database, Cytoscape and MCODE were applied to construct the protein-protein interaction (PPI) network and screen hub genes. Pathway enrichment analysis was further performed for hub genes and gene clusters identified via module analysis.

Results

A total of 107 DEGs were identified in CAVD (53 up-regulated genes, and 54 down-regulated genes), and they were mainly enriched in the terms of immune response, extracellular matrix organization, leukocyte transendothelial migration, cell adhesion molecules (CAMs), and fatty acid metabolism. Five hub genes including VCAM1, MMP9, ITGB2, RAC2, and vWF were identified via PPI network, which were mainly enriched in terms of leukocyte transendothelial migration and cell adhesion. An independently down-regulated protein cluster containing ALDH2, HIBCH, ACADVL, ECHDC2, VAT1L, and MAOA was also identified via PPI network.

Conclusions

The present study identified VCAM1, MMP9, ITGB2, RAC2, vWF and ALDH2 as key genes in the progression of CAVD. Immune cells infiltration might play a key role in the progression of CAVD, while ALDH2-mediated detoxification effect might play a protective role in CAVD. Further studies are needed to elucidate the pathogenesis of CAVD.

In vivo alpha-V beta-3 integrin expression in human aortic atherosclerosis

OBJECTIVES

Intraplaque angiogenesis and inflammation are key promoters of atherosclerosis and are mediated by the alpha-V beta-3 (αvβ3) integrin pathway. We investigated the applicability of the αvβ3-integrin receptor-selective positron emission tomography (PET) radiotracer 18F-fluciclatide in assessing human aortic atherosclerosis.

METHODS

Vascular 18F-fluciclatide binding was evaluated using ex vivo analysis of carotid endarterectomy samples with autoradiography and immunohistochemistry, and in vivo kinetic modelling following radiotracer administration. Forty-six subjects with a spectrum of atherosclerotic disease categorised as stable (n=27) or unstable (n=19; recent myocardial infarction) underwent PET and CT imaging of the thorax after administration of 229 (IQR 217-237) MBq 18F-fluciclatide. Thoracic aortic 18F-fluciclatide uptake was quantified on fused PET-CT images and corrected for blood-pool activity using the maximum tissue-to-background ratio (TBRmax). Aortic atherosclerotic burden was quantified by CT wall thickness, plaque volume and calcium scoring.

RESULTS

18F-Fluciclatide uptake co-localised with regions of increased αvβ3 integrin expression, and markers of inflammation and angiogenesis. 18F-Fluciclatide vascular uptake was confirmed in vivo using kinetic modelling, and on static imaging correlated with measures of aortic atherosclerotic burden: wall thickness (r=0.57, p=0.001), total plaque volume (r=0.56, p=0.001) and aortic CT calcium score (r=0.37, p=0.01). Patients with recent myocardial infarction had greater aortic 18F-fluciclatide uptake than those with stable disease (TBRmax 1.29 vs 1.21, p=0.02).

CONCLUSIONS

In vivo expression of αvβ3 integrin in human aortic atheroma is associated with plaque burden and is increased in patients with recent myocardial infarction. Quantification of αvβ3 integrin expression with 18F-fluciclatide PET has potential to assess plaque vulnerability and disease activity in atherosclerosis.