New therapeutic perspectives for vascular and valvular calcifications in chronic kidney disease.

PURPOSE OF REVIEW: Vascular and valvular calcification are associated with cardiovascular morbidity and mortality in people with chronic kidney disease (CKD). Uncertainty exists regarding therapeutic strategies to attenuate calcification. This review outlines the pathophysiological mechanisms contributing to vascular and valvular calcification, considers the mechanisms of action of therapeutic interventions, and reports the latest outcomes from interventional studies. RECENT FINDINGS: Conventional therapies targeted at CKD-mineral and bone disorder (MBD) modulation have yielded conflicting or inconclusive results. Magnesium and vitamin K supplementation appear to offer attenuation of coronary artery calcification but inconsistent findings justify the need for further studies. Strategies targeting hydroxyapatite formation such as sodium thiosulphate and hexasodium fytate show promise and are worthy of further evaluation. The serum calcification propensity assay (T50) correlates with severity and progression; it holds promise as a potential future clinical tool for screening monitoring calcification risk. SUMMARY: Whilst knowledge of the pathophysiology of vascular calcification has grown and therapeutic approaches appear promising, as yet no medication has been approved to treat vascular or valvular calcification, or calciphylaxis.

Calcification of Various Bioprosthetic Materials in Rats: Is It Really Different?

The causes of heart valve bioprosthetic calcification are still not clear. In this paper, we compared the calcification in the porcine aorta (Ao) and the bovine jugular vein (Ve) walls, as well as the bovine pericardium (Pe). Biomaterials were crosslinked with glutaraldehyde (GA) and diepoxide (DE), after which they were implanted subcutaneously in young rats for 10, 20, and 30 days. Collagen, elastin, and fibrillin were visualized in non-implanted samples. Atomic absorption spectroscopy, histological methods, scanning electron microscopy, and Fourier-transform infrared spectroscopy were used to study the dynamics of calcification. By the 30th day, calcium accumulated most intensively in the collagen fibers of the GA-Pe. In elastin-rich materials, calcium deposits were associated with elastin fibers and localized differences in the walls of Ao and Ve. The DE-Pe did not calcify at all for 30 days. Alkaline phosphatase does not affect calcification since it was not found in the implant tissue. Fibrillin surrounds elastin fibers in the Ao and Ve, but its involvement in calcification is questionable. In the subcutaneous space of young rats, which are used to model the implants' calcification, the content of phosphorus was five times higher than in aging animals. We hypothesize that the centers of calcium phosphate nucleation are the positively charged nitrogen of the pyridinium rings, which is the main one in fresh elastin and appears in collagen as a result of GA preservation. Nucleation can be significantly accelerated at high concentrations of phosphorus in biological fluids. The hypothesis needs further experimental confirmation.

Single-cell RNA sequencing reveals the diversity and biology of valve cells in cardiac valve disease.

From highly aligned extracellular fibrils to the cells, a multilevel ordered hierarchy in valve leaflets is crucial for their biological function. Cardiac valve pathology most frequently involves a disruption in normal structure-function correlations through abnormal and complex interaction of cells, extracellular matrix, and their environment. At present, effective treatment for valve disease is limited and frequently ends with surgical repair or replacement with a mechanical or artificial biological cardiac valve, which comes with insuperable complications for many high-risk patients including aged and pediatric populations. Therefore, there is a critical need to fully appreciate the pathobiology of valve disease in order to develop better, alternative therapies. To date, the majority of studies have focused on delineating valve disease mechanisms at the cellular level. However, the cellular heterogeneity and function is still unclear. In this review, we summarize the body of work on valve cells, with a particular focus on the discoveries about valve cells heterogeneity and functions using single-cell RNA sequencing. We conclude by discussing state-of-the-art strategies for deciphering heterogeneity of these complex cell types, and argue this knowledge could translate into the improved personalized treatment of cardiac valve disease.

18F-Sodium Fluoride PET/CT in Assessing Valvular Heart and Atherosclerotic Diseases.

Aortic valve stenosis is the most common valvular disease in Western countries, while atherosclerotic cardiovascular disease is the foremost cause of death and disability worldwide. Valve degeneration and atherosclerosis are mediated by inflammation and calcification and inevitably progress over time. Computed tomography can visualise the later stages of macroscopic calcification but fails to assess the early stages of microcalcification and cannot differentiate active from burnt out disease states. Molecular imaging has the ability to provide complementary information related to disease activity, which may allow us to detect disease early, to predict disease progression and to monitor preventive or therapeutic strategies for in both aortic stenosis and atherosclerosis. PET/CT is a non-invasive imaging technique that enables visualization of ongoing molecular processes within small structures, such as the coronary arteries or heart valves. 18F-sodium fluoride (18F-NaF) binds hydroxyapatite deposits in the extracellular matrix, with preferential binding to newly developing deposits of microcalcification, which provides an assessment of calcification activity. In recent years, 18F-NaF has attracted the attention of many research groups and has been evaluated in several pathological cardiovascular processes. Histologic validation of the 18F-NaF PET signal in valvular disease and atherosclerosis has been reported in multiple independent studies. The selective high-affinity binding of 18F-NaF to microscopic calcified deposits (beyond the resolution of µCT) has been demonstrated ex vivo, as well as its ability to distinguish between areas of macro- and active microcalcification. In addition, prospective clinical studies have shown that baseline 18F-NaF uptake in patients with aortic stenosis and mitral annular calcification is correlated with subsequent calcium deposition and valvular dysfunction after a follow-up period of 2 years. In patients with surgical bioprosthetic aortic valves but without morphological criteria for prosthetic degeneration, increased 18F-NaF uptake at baseline was associated with subsequent bioprosthetic degeneration over time. Similar data were obtained in a cohort of patients with transcatheter aortic valve implantation. Furthermore, several studies have confirmed the association of coronary 18F-NaF uptake with adverse atherosclerotic plaque features, active disease and future disease progression. 18F-NaF uptake is also associated with future fatal or nonfatal myocardial infarction in patients with established coronary artery disease. The link between 18F-NaF uptake and active atherosclerotic disease has not only been demonstrated in the coronary arteries, but also in peripheral arterial disease, abdominal aortic aneurysms and carotid atherosclerosis. It can be assumed that 18F-NaF PET/CT will strengthen the diagnostic toolbox of practitioners in the coming years. Indeed, there is a strong medical need to diagnose degenerative valvular disease and to detect active atherosclerotic disease states. Finally, the use of 18F-NaF as a biomarker to monitor the efficacy of drug therapies in preventing these pathological processes is attractive. In this review, we consider the role of 18F-NaF PET/CT imaging in cardiac valvular diseases and atherosclerosis.

Key nutrients important in the management of canine myxomatous mitral valve disease and heart failure.

The most common cause of heart failure in dogs is myxomatous mitral valve disease (MMVD), which accounts for approximately 75% of canine heart disease cases and is especially common in smaller dogs. Although low-sodium diets have been recommended for humans with heart diseases for decades, there is little evidence to support this practice in dogs. In recent years, however, it has become clear that other nutrients are important to heart health. Dogs with heart disease secondary to MMVD experience patterns of metabolic changes that include decreased mitochondrial energy metabolism and ATP availability, with increased oxidative stress and inflammation. These changes occur early in disease and progress with worsening heart disease. Key nutrients that may support normal function and address these changes include omega-3 fatty acids, medium-chain triglycerides, magnesium, antioxidants including vitamin E and taurine, and the amino acids methionine and lysine. The long-chain omega-3 fatty acids provide anti-inflammatory, antithrombotic, and other benefits. Medium-chain fatty acids and ketones derived from medium-chain triglycerides provide an alternative energy source for cardiac mitochondria and help reduce free radical production. Magnesium supports mitochondrial function, normal cardiac rhythm, and provides other benefits. Both vitamin E and taurine counter oxidative stress, and taurine also has direct cardiac benefits. Dogs with MMVD have reduced plasma methionine. Methionine and lysine are important for carnitine production as well as other functions. This article reviews the evidence supporting the functions and benefits of these and other nutrients in MMVD and other cardiac conditions.

Whole blood and plasma taurine reference intervals in adult Cavalier King Charles Spaniels and correlations between taurine concentration, diet and mitral valve disease.

OBJECTIVE: To determine breed-specific reference intervals for whole blood (WB) and plasma taurine concentrations in adult, overtly healthy Cavalier King Charles Spaniels (CKCSs) and determine whether taurine concentrations differ across preclinical myxomatous mitral valve disease (MMVD) stages or between CKCSs eating diets that meet World Small Animal Veterinary Association (WSAVA) nutritional guidelines versus other diets. ANIMALS: 200 privately owned CKCSs. PROCEDURES: Clinically healthy adult CKCSs were recruited prospectively. Diet and supplement history was collected. Dogs were staged by echocardiography using MMVD consensus guidelines. Taurine concentrations were measured in deproteinized lithium heparin WB and plasma samples with the postcolumn ninhydrin derivatization method on a dedicated amino acid analyzer. RESULTS: There were 12 stage A (6%), 150 stage B1 (75%), and 38 stage B2 (19%) CKCSs. Seventy-eight dogs (39%) were reported by their owners to be eating diets meeting WSAVA nutritional guidelines; 116 (58%) were not. Taurine concentrations in plasma (P = .444) and WB (P = .073) were not significantly different across MMVD stages or between CKCSs eating diets meeting WSAVA nutritional guidelines versus other diets (P = .345 and P = .527, respectively). Reference intervals for WB taurine (152 to 373 µM) and plasma taurine (51 to 217 µM) concentrations in CKCSs were generated. CLINICAL RELEVANCE: In CKCSs, taurine concentrations do not differ significantly based on preclinical MMVD stage, nor do they differ significantly based on consumption of a diet that does or does not meet WSAVA nutritional guidelines.

Overview of mitral valve replacement versus mitral valve repair due to ischemic papillary muscle rupture: A meta-analysis inspired by a case report.

BACKGROUND: Papillary muscle rupture (PMR) is an infrequent but catastrophic complication after myocardial infarction (MI). Surgical procedure is considered the optimal treatment, despite high risk. However, the gold standard technique is still a major dilemma. Therefore, a meta-analysis was carried out to assess and provide an overview comparing mitral valve replacement (MVR) and mitral valve repair (MVr) for PMR post-MI. METHODS: A systematic literature search was performed. Data were extracted and verified using a standardized data extraction form. Meta-analysis was realized mainly using RevMan 5.4 software. RESULTS: From four observational studies 1640 patients were identified; 81% underwent MVR and 19% MVr. Operative mortality results were significantly higher in MVR group than the MVr group. MVR was performed under emergency conditions and patients admitted in cardiogenic shock or who required the use of mechanical cardiac support underwent MVR. MVr had shorter time of hospitalization and similar incidence of postoperative complications than MVR. No significant differences existed between the two procedures regarding cardiopulmonary bypass time. CONCLUSIONS: Mitral valve repair appears to be a viable alternative to MVR for post-MI PMR, given that it has lower operative mortality, shorter time of hospitalization and similar incidence of short-term postoperative complications than MVR. However, it needs to be pointed out that MVR was associated with the most critical clinical condition following PMR. There is uncertainty regarding the overall survival and improvement of the quality of life between the procedures. Nevertheless, further completed investigation is required.

Enhanced Detection of Heart Valve Disease Using Integrated Artificial Intelligence at Scale.

BACKGROUND: Undertreatment of heart valve disease creates unnecessary patient risk. Poorly integrated healthcare data systems are unequipped to solve this problem. A software program using a rules-based algorithm to search the electronic health record for heart valve disease among patients treated by healthcare systems in the United States may provide a solution. METHODS: A software interface allowed concurrent access to picture archiving communication systems, the electronic health record, and other sources. The software platform was created to programmatically run a rules engine to search structured and unstructured data for identification of moderate or severe heart valve disease using guideline-reported values. Incidence and progression of disease as well as compliance with a care pathway were assessed. RESULTS: In 2 health institutions in the United States 60,145 patients had 77,215 echocardiograms. Moderate or severe aortic stenosis (AS) was identified at a rate of 9.1% of patients (5474 and 6910 echocardiograms) in this population. The precision and accuracy of the algorithm for the detection of moderate or severe AS was 92.9% and 98.6%, respectively. Thirty-five percent of patients (441/1265) with moderate stenosis and a subsequent echocardiogram progressed to severe stenosis (mean interval, 358 days). In 1 sample 70.3% of moderate AS patients lacked a 6-month echocardiogram or appointment. The platform enabled 100% accountability for all patients with severe AS. CONCLUSIONS: A rules-based software program enhances detection of heart valve disease and can be used to measures disease progression and care pathway compliance.

Current Perspectives on Contemporary Rheumatic Mitral Valve Repair.

The surgical management of rheumatic mitral valve disease remains a challenge for cardiac surgeons. Durability of mitral valve repair (MVr) is likely compromised not simply due to high technical demand, but surgeon reluctance, despite boasting copious advantages over MV replacement. This comprehensive review aims to evoke a deeper understanding of MVr concepts necessary to abate these limitations and shift mindset towards a more holistic approach to repair. Details of commonly utilized techniques in contemporary MVr for rheumatic heart disease will be discussed. Of importance, the reparative procedures will be mapped to an in-depth physiological exploration of the mitral complex-dynamism and rheumatic interplay. This is further emphasized by outlining the current "aggressive" resection strategy in contemporary rheumatic MVr.

Current methods to assess mitral annular calcification and its risk factors.

INTRODUCTION: Mitral annulus calcification (MAC) is a chronic, non-inflammatory, degenerative mechanism of the fibrous base of the mitral valve. While MAC was originally thought to be an age-related degenerative process, there is evidence that other mechanisms, such as atherosclerosis and abnormal calcium phosphorus metabolism, also contribute to the development of MAC. AREAS COVERED: This paper summarizes, existing perception of clinically valid definition of MAC and the pathophysiological processes that lead to the development of MAC and the diagnostic implications of this disease entity. EXPERT OPINION: Minimal evidence exists on the natural history and progression of MAC. Characterization of MAC progression and identification of predisposing risk factors can help to validate hypotheses. MAC is most commonly asymptomatic and incidental finding. Echocardiography is the primary imaging modality for identification and characterization of MAC and associated mitral valve (MV) disease. For patients with an indication for MV surgery, computed tomography (CT) is a complementary imaging modality for MAC. MAC is generally recognized by its characteristic density, location, and shape on echocardiography and CT, unusual variants are sometimes confused with other lesions.

Warfarin maintenance dose prediction for Chinese after heart valve replacement by a feedforward neural network with equal stratified sampling.

Patients requiring low-dose warfarin are more likely to suffer bleeding due to overdose. The goal of this work is to improve the feedforward neural network model's precision in predicting the low maintenance dose for Chinese in the aspect of training data construction. We built the model from a resampled dataset created by equal stratified sampling (maintaining the same sample number in three dose-groups with a total of 3639) and performed internal and external validations. Comparing to the model trained from the raw dataset of 19,060 eligible cases, we improved the low-dose group's ideal prediction percentage from 0.7 to 9.6% and maintained the overall performance (76.4% vs. 75.6%) in external validation. We further built neural network models on single-dose subsets to invest whether the subsets samples were sufficient and whether the selected factors were appropriate. The training set sizes were 1340 and 1478 for the low and high dose subsets; the corresponding ideal prediction percentages were 70.2% and 75.1%. The training set size for the intermediate dose varied and was 1553, 6214, and 12,429; the corresponding ideal prediction percentages were 95.6, 95.1%, and 95.3%. Our conclusion is that equal stratified sampling can be a considerable alternative approach in training data construction to build drug dosing models in the clinic.

Protective effects of omega-3 fatty acids in dogs with myxomatous mitral valve disease stages B2 and C.

Myxomatous mitral valve disease (MMVD) is characterized by thickening of the valve leaflets and omega-3 (ω-3) supplementation has been associated with modulation of blood pressure (BP) and heart rate, improvement of doppler echocardiographic indices, antiarrhythmic, anti-inflammatory and anti-dislipidemic effects in dogs and humans, although prospective studies of it single use are still absent in the veterinary literature. The objective of this study was to evaluate the influence of ω-3 supplementation in dogs with MMVD. Twenty-nine dogs were followed quarterly for 12 months by clinical evaluation, arterial blood pressure, electrocardiography, doppler echocardiography, thoracic radiography and laboratory tests including inflammatory mediators and cardiac biomarker blood concentrations. The dogs were classified in stages B2 and C, according to the classification proposed by ACVIM 2019. They were randomly assigned to either ω-3 group (ω-3G) or control group (CG). The ingestion of ω-3 reduced the chance of developing arrhythmias by 2.96 times (p = 0.003). The vertebral heart size (VHS) measurements were higher in the control group (p = 0.033). In conclusion, at the dosages used in this study, ω-3 dietary supplementation reduces the volumetric overload, has antiarrhythmic effect and keeps dogs with B2 and C stages of MMVD in milder stages of the disease.

Ginkgo Biloba Extract EGB761 Alleviates Warfarin-induced Aortic Valve Calcification Through the BMP2/Smad1/5/Runx2 Signaling Pathway.

ABSTRACT: Calcific aortic valve disease is a common heart disease that contributes to increased cardiovascular morbidity and mortality. There is a lack of effective pharmaceutical therapy because its mechanisms are not yet fully known. Ginkgo biloba extract (EGB761) is reported to alleviate vascular calcification. However, whether EGB761 protects against aortic valve calcification, a disease whose pathogenesis shares many similarities with vascular calcification, and potential molecular mechanisms remain unknown. In this study, porcine aortic valve interstitial cell (pAVIC) calcification was induced by warfarin with or without the presence of EGB761. Immunostaining was performed to establish and characterize the pAVIC phenotype. Calcium deposition and calcium content were examined by Alizarin Red S staining and an intracellular calcium content assay. Alkaline phosphatase activity was detected by the p-nitrophenyl phosphate method. The expression levels of bone morphogenetic protein-2 (BMP2), Runt-related transcription factor 2 (Runx2), homeobox protein MSX-2, and phosphorylated (p)-Smad1/5 were detected by reverse transcription-quantitative polymerase chain reaction (PCR) and Western blot analysis. Consistent with these in vitro data, we also confirmed the suppression of in vivo calcification by EGB761 in the warfarin-induced C57/Bl6 mice. The results indicated that both pAVICs and aortic valves tissue of mice stimulated with warfarin showed increased calcium deposition and expression of osteogenic markers (alkaline phosphatase, BMP2, homeobox protein MSX-2, and Runx2) and promoted p-Smad1/5 translocation from the cytoplasm to the nucleus. The addition of EGB761 significantly inhibited p-Smad1/5 translocation from the cytoplasm to the nucleus, thus suppressing calcification. In conclusion, EGB761 could ameliorate warfarin-induced aortic valve calcification through the inhibition of the BMP2-medicated Smad1/5/Runx2 signaling pathway.

Comparison of Direct Oral Anticoagulants Versus Warfarin in Patients With Atrial Fibrillation and Bioprosthetic Heart Valves.

There are limited data regarding direct oral anticoagulants (DOACs) for stroke prevention in patients with bioprosthetic heart valves (BHVs) and atrial fibrillation (AF). The objectives of this study were to evaluate the ambulatory utilization of DOACs and to compare the effectiveness and safety of DOACs versus warfarin in patients with AF and BHVs. We conducted a retrospective cohort study at a large integrated health care delivery system in California. Patients with BHVs and AF treated with warfarin, dabigatran, rivaroxaban, or apixaban between September 12, 2011 and June 18, 2020 were identified. Inverse probability of treatment-weighted comparative effectiveness and safety of DOACs compared with warfarin were determined. Use of DOACs gradually increased since 2011, with a significant upward in trend after a stay-at-home order related to COVID-19. Among 2,672 adults with BHVs and AF who met the inclusion criteria, 439 were exposed to a DOAC and 2233 were exposed to warfarin. For the primary effectiveness outcome of ischemic stroke, systemic embolism and transient ischemic attack, no significant association was observed between use of DOACs compared with warfarin (HR 1.19, 95% CI 0.96 to 1.48, p = 0.11). Use of DOACs was associated with lower risk of the primary safety outcome of intracranial hemorrhage, gastrointestinal bleeding, and other bleed (HR 0.69, 95% CI 0.56 to 0.85, p < 0.001). Results were consistent across multiple subgroups in the sensitivity analyses. These findings support the use of DOACs for AF in patients with BHVs.

Trace elements in patients with aortic valve sclerosis.

BACKGROUND: Aortic valve sclerosis (AVSc) is defined as the thickening and calcification of aortic valve cusps, in the absence of obstruction of ventricular outflow. AVSc is linked with a clear imbalance in some trace elements. AIMS: The objective of this study was to investigate the relationship between AVSc and serum levels of iron (Fe), zinc (Zn), selenium (Se), and copper (Cu). Additionally, this research aimed to explore the clinical significance of human serum zinc, selenium, copper, and iron concentrations as a potential new biomarker for AVSc patients and to clarify the pathophysiological role in individuals at risk of developing AVSc. PATIENTS AND METHODS: The study included 40 subjects with AVSc (25% male and 75% female) who were compared with a healthy control group with the same gender ratio. AVSc was based on comprehensive echocardiographic assessments. Blood samples were taken and Zn and Cu concentrations were determined through the use of atomic absorption spectroscopy. Se was measured using an inductively coupled plasma mass spectrometry device and Fe was measured using a Beckman Coulter instrument. RESULTS: There was a significant difference in the prevalence of diabetes, blood pressure levels, and body mass index between the patients and the healthy subjects (p < 0.05). The differences between the serum Fe, Se, and Cu levels of the AVSc patients and the healthy subjects (p > 0.05) were recorded. The serum Zn of AVSc patients when compared was significantly lower compared with that of the control group (p < 0.01). CONCLUSION: Patients with AVSc had an imbalance in some of the trace elements in their blood. The patient group's valves had higher serum Cu levels and lower serum Se, Zn, and Fe concentrations compared with the healthy group's valves. In the valve patients as compared, AVSc had a high prevalence of obesity, hypertension, and diabetes.

Risk factors associated with valvular calcification in patients with chronic kidney disease. Analysis of NEFRONA study.

INTRODUCTION: Patients with chronic kidney disease (CKD) are at high risk of cardiovascular morbidity and mortality. Subclinical cardiac structural alterations have prognostic value in these patients. The aim was to analyse the prevalence of valvular calcification, the evolution and the relationship with different risk factors. MATERIAL AND METHODS: Part of the sample of the NEFRONA study was randomly selected. Aortic and mitral valve calcification were analysed in echocardiograms performed at the baseline visit and at 24 months. RESULTS: We included 397 patients, the estimated basal glomerular filtrate (eGFR) was 33 ml/min with significant decrease to 30.9 ml/min. There was an increase in the area of carotid and femoral plaque, as well as an increase in patients with aortic and mitral calcification at 24 months. A positive association of mitral calcification at 24 months with age, ankle-brachial index (ABI) and calcium-phosphorus product (CaxP) at baseline visit was observed, without association with eGFR. Aortic calcification at 24 months was positively associated with age, phosphorous and total carotid plaque area at baseline, with no relationship to eGFR. CONCLUSIONS: A significant prevalence of valvular calcification was observed in patients with CKD without known cardiovascular disease.Two-year progression was observed independently of the eGFR. Patients with higher risk of mitral valve calcification were those with older age, higher ABI and CaxP product. Patients with a higher risk of aortic calcification were those with older age, higher phosphorous levels and larger area of carotid plaque. Identifying these higher risk patients would help to avoid future cardiovascular events intensifying follow-ups.

Zinc ameliorates human aortic valve calcification through GPR39 mediated ERK1/2 signalling pathway.

AIMS: Calcific aortic valve disease (CAVD) is the most common heart valve disease in the Western world. It has been reported that zinc is accumulated in calcified human aortic valves. However, whether zinc directly regulates CAVD is yet to be elucidated. The present study sought to determine the potential role of zinc in the pathogenesis of CAVD. METHODS AND RESULTS: Using a combination of a human valve interstitial cell (hVIC) calcification model, human aortic valve tissues, and blood samples, we report that 20 µM zinc supplementation attenuates hVIC in vitro calcification, and that this is mediated through inhibition of apoptosis and osteogenic differentiation via the zinc-sensing receptor GPR39-dependent ERK1/2 signalling pathway. Furthermore, we report that GPR39 protein expression is dramatically reduced in calcified human aortic valves, and there is a significant reduction in zinc serum levels in patients with CAVD. Moreover, we reveal that 20 µM zinc treatment prevents the reduction of GPR39 observed in calcified hVICs. We also show that the zinc transporter ZIP13 and ZIP14 are significantly increased in hVICs in response to zinc treatment. Knockdown of ZIP13 or ZIP14 significantly inhibited hVIC in vitro calcification and osteogenic differentiation. CONCLUSIONS: Together, these findings suggest that zinc is a novel inhibitor of CAVD, and report that zinc transporter ZIP13 and ZIP14 are important regulators of hVIC in vitro calcification and osteogenic differentiation. Zinc supplementation may offer a potential therapeutic strategy for CAVD.

Expertise, experience, and excellence. Twenty years of patient involvement in health technology assessment at NICE: an evolving story.

From its inception in 1999, the National Institute for Health and Care Excellence (NICE) committed to including the expertise, experiences, and perspectives of lay people, patients and carers, and patient organizations in its health technology assessments (HTAs). This is our story of patient involvement in HTA: from early methods designed for use when assessing medicines, widening to address the different requirements of HTAs for interventional procedures, medical technologies, and diagnostic technologies. We also chart the evolution and development of all our patient involvement methods over the past 20 years through regular evaluation and by responding to external challenge. However, we know that processes and methods alone are not enough. Through case studies we demonstrate the value of patient involvement in HTA and highlight the unique perspectives and experiences that patients bring to HTA committees. Finally, we discuss the underpinning principles and commitments that have made NICE a world leader in delivering meaningful and legitimate patient involvement.