TAVR in Older Adults: Moving Toward a Comprehensive Geriatric Assessment and Away From Chronological Age: JACC Family Series

Calcific aortic stenosis can be considered a model for geriatric cardiovascular conditions due to a confluence of factors. The remarkable technological development of transcatheter aortic valve replacement was studied initially on older adult populations with prohibitive or high-risk for surgical valve replacement. Through these trials, the cardiovascular community has recognized that stratification of these chronologically older adults can be improved incrementally by invoking the concept of frailty and other geriatric risks. Given the complexity of the aging process, stratification by chronological age should only be the initial step but is no longer sufficient to optimally quantify cardiovascular and noncardiovascular risk. In this review, we employ a geriatric cardiology lens to focus on the diagnosis and the comprehensive management of aortic stenosis in older adults to enhance shared decision-making with patients and their families and optimize patient-centered outcomes. Finally, we highlight knowledge gaps that are critical for future areas of study.

Cholesterol Crystal Dissolution Rate of Serum Predicts Outcomes in Patients With Aortic Stenosis Undergoing Transcatheter Aortic Valve Replacement

BACKGROUND

Aortic stenosis has pathophysiological similarities with atherosclerosis, including the deposition of cholesterol-containing lipoproteins. The resulting cholesterol crystals activate the NLRP3 (NOD-like receptor protein 3) inflammasome, leading to inflammation and cardiovascular diseases. We aimed to investigate the cholesterol crystal dissolution rate (CCDR) of serum in patients with aortic stenosis and to assess the prognostic value of this biomarker.

METHODS AND RESULTS

The study included 348 patients with aortic stenosis undergoing transcatheter aortic valve replacement. The CCDR was measured using flow cytometry to enumerate cholesterol crystals that were added to a serum solution, at baseline and after 2 hours of incubation. Based on the median CCDR, the cohort was stratified into high and low cholesterol crystal dissolvers. The incidence of the primary end point, a composite of 1-year all-cause mortality and major vascular complication, was significantly lower in the high CCDR group (7.3 per 100 person-years) compared with the low CCDR group (17.0 per 100 person-years, P=0.01). This was mainly driven by a lower 1-year mortality rate in patients with a high CCDR (7.3 versus 15.1 per 100 person-years, P=0.04). Unplanned endovascular interventions were significantly less frequent in high cholesterol crystal dissolvers (12.8 versus 22.6 per 100 person-years, P=0.04). Although low-density lipoprotein cholesterol levels were comparable in both groups (101.8±37.3 mg/dL versus 97.9±37.6 mg/dL, P=0.35), only patients with a low CCDR showed a benefit from statin treatment. In multivariate analysis, low CCDR (hazard ratio, 2.21 [95% CI, 0.99-4.92], P=0.04) was significantly associated with 1-year mortality.

CONCLUSIONS

The CCDR is a novel biomarker associated with outcome in patients with aortic stenosis undergoing transcatheter aortic valve replacement. It may provide new insights into patients' anti-inflammatory capacity and additional prognostic information beyond classic risk assessment.

Embedding and Backscattered Scanning Electron Microscopy (EM-BSEM) Is Preferential over Immunophenotyping in Relation to Bioprosthetic Heart Valves

Hitherto, calcified aortic valves (AVs) and failing bioprosthetic heart valves (BHVs) have been investigated by similar approaches, mostly limited to various immunostaining techniques. Having employed multiple immunostaining combinations, we demonstrated that AVs retain a well-defined cellular hierarchy even at severe stenosis, whilst BHVs were notable for the stochastic degradation of the extracellular matrix (ECM) and aggressive infiltration by ECM-digesting macrophages. Leukocytes (CD45+) comprised ≤10% cells in the AVs but were the predominant cell lineage in BHVs (≥80% cells). Albeit cells with uncertain immunophenotype were rarely encountered in the AVs (≤5% cells), they were commonly found in BHVs (≥80% cells). Whilst cell conversions in the AVs were limited to the endothelial-to-mesenchymal transition (represented by CD31+α-SMA+ cells) and the formation of endothelial-like (CD31+CD68+) cells at the AV surface, BHVs harboured numerous macrophages with a transitional phenotype, mostly CD45+CD31+, CD45+α-SMA+, and CD68+α-SMA+. In contrast to immunostaining, which was unable to predict cell function in the BHVs, our whole-specimen, nondestructive electron microscopy approach (EM-BSEM) was able to distinguish between quiescent and matrix-degrading macrophages, foam cells, and multinucleated giant cells to conduct the ultrastructural analysis of organelles and the ECM, and to preserve tissue integrity. Hence, we suggest EM-BSEM as a technique of choice for studying the cellular landscape of BHVs.

Global Oxidative Status Is Linked to Calcific Aortic Stenosis: The Differences Due to Diabetes Mellitus and the Effects of Metformin

Calcific aortic stenosis (CAS) and type 2 diabetes mellitus (T2DM) are related and often concomitant pathologies, accompanied by common comorbidities such as hypertension or dyslipidemia. Oxidative stress is one of the mechanisms that trigger CAS, and it can drive the vascular complications in T2DM. Metformin can inhibit oxidative stress, yet its effects have not been studied in the context of CAS. Here, we assessed the global oxidative status in plasma from patients with CAS, both alone and with T2DM (and under treatment with metformin), using multimarker scores of systemic oxidative damage (OxyScore) and antioxidant defense (AntioxyScore). The OxyScore was determined by measuring carbonyls, oxidized LDL (oxLDL), 8-hydroxy-20-deoxyguanosine (8-OHdG), and xanthine oxidase (XOD) activity. In contrast, the AntioxyScore was determined through the catalase (CAT) and superoxide dismutase (SOD) activity, as well as the total antioxidant capacity (TAC). Patients with CAS displayed enhanced oxidative stress compared to control subjects, probably exceeding their antioxidant capacity. Interestingly, patients with CAS and T2DM displayed less oxidative stress, possibly due to the benefits of their pharmacological therapy (metformin). Thus, reducing oxidative stress or enhancing antioxidant capacity through specific therapies could be a good strategy to manage CAS, focusing on personalized medicine.

Role of follistatin-like 1 levels and functions in calcific aortic stenosis

Background

Calcific aortic valve disease (CAVD) is a progressive disease resulting in severe calcific aortic stenosis (AS), and there is increasing interest in the discovery of novel biomarkers to identify patients with potential future calcific AS at an early stage. This study aimed to determine whether follistatin-like 1 (FSTL1) is associated with calcific AS events and its exact role in aortic valve calcification.

Methods

A prospective observational cohort study involving 656 patients was performed to investigate the relationship between serum FSTL1 and calcific AS incidence during a follow-up of 5 years. Furthermore, we detected FSTL1 levels in valvular interstitial cells (VICs) from calcified valves and explored the effects of FSTL1 on VIC osteogenic differentiation in vitro as well as the signaling pathways involved.

Results

During a median follow-up of 5 years, lower FSTL1 levels were associated with a significantly higher risk of calcific AS events (log rank test, P = 0.007). In addition, Cox multivariable regression analyses verified the predictive value of FSTL1 after adjusting for both demographic features and laboratory confounders. Consistent with our results for serum, a lower concentration of FSTL1 was observed in calcified human valves (n = 11) and mainly colocalized with VICs. Recombinant human FSTL1 (rhFSTL1) stimulation inhibited calcium deposition, alkaline phosphatase (ALP) activity, and osteogenic gene expression partly through the downregulation of the ERK1/2 pathway.

Conclusion

Taken together, this study provides a strong rationale to consider FSTL1 as a potential therapeutic target for calcific AS.

Towards Personalized Therapy of Aortic Stenosis

Calcific aortic stenosis (CAS) is the most common cause of acquired valvular heart disease in adults with no available pharmacological treatment to inhibit the disease progression to date. This review provides an up-to-date overview of current knowledge of molecular mechanisms underlying CAS pathobiology and the related treatment pathways. Particular attention is paid to current randomized trials investigating medical treatment of CAS, including strategies based on lipid-lowering and antihypertensive therapies, phosphate and calcium metabolism, and novel therapeutic targets such as valvular oxidative stress, coagulation proteins, matrix metalloproteinases, and accumulation of advanced glycation end products.

Epicardial fat thickness assessment by multi-slice computed tomography for predicting cardiac outcomes in patients undergoing transcatheter aortic valve implantation

INTRODUCTION

Chronic inflammation promotes aortic valve calcification. It is known that epicardial fat is a source of inflammation. The aim of this study was to investigate the relationship between epicardial fat thickness, cardiac conduction disorders and outcomes in patients undergoing transcatheter aortic valve implantation (TAVI).

METHODS

During a three-year period, 45 patients with severe aortic stenosis who underwent TAVI were recruited to the study. Data were collected retrospectively. Epicardial fat was defined as the adipose tissue between the epicardium and the visceral pericardium. Mean epicardial fat thickness was determined by multi-slice computed tomography, which was performed before the procedure.

RESULTS

The average thickness of epicardial fat was 13.06 ± 3.29 mm. This study failed to reveal a significant correlation between epicardial fat thickness and post-procedural left bundle branch block, right bundle branch block, paravalvular aortic regurgitation and pacemaker implantation rates (p > 0.05).

CONCLUSIONS

The results of this study failed to show a significant relationship between epicardial fat thickness, cardiac conduction disorders and outcomes, however further studies with larger sample numbers are required to explore the relationship.

Calcific Aortic Stenosis-A Review on Acquired Mechanisms of the Disease and Treatments

Calcific aortic stenosis is a progressive disease that has become more prevalent in recent decades. Despite advances in research to uncover underlying biomechanisms, and development of new generations of prosthetic valves and replacement techniques, management of calcific aortic stenosis still comes with unresolved complications. In this review, we highlight underlying molecular mechanisms of acquired aortic stenosis calcification in relation to hemodynamics, complications related to the disease, diagnostic methods, and evolving treatment practices for calcific aortic stenosis.

The current landscape of lipoprotein(a) in calcific aortic valvular disease

PURPOSE OF REVIEW

Calcific aortic stenosis (CAVS) is the most common form of valvular heart disease in developed countries, increasing in prevalence with the aging population. Surgical or transcatheter aortic valve replacement is the only treatment available for CAVS. However, these interventions are typically reserved for severe symptomatic aortic stenosis (AS). The purpose of this review is to summarize the recent literature in uncovering the underlying pathophysiology of CAVS in the setting of lipoprotein (a) [Lp(a)] and emerging therapies targeting Lp(a) which may help halt disease progression in CAVS.

RECENT FINDINGS

Pathophysiologic, epidemiological, and genetic studies over the past two decades have provided strong evidence that Lp(a) is an important mediator of calcific aortic valvular disease (CAVD). Studies suggest that Lp(a) is a key carrier of pro-calcifying oxidized phospholipids (OxPL). The metabolism of OxPL results in a pro-inflammatory state and subsequent valvular thickening and mineralization through pro-osteogenic signaling. The identification of Lp(a) as a causal mediator of CAVD has allowed for opportunities for emerging therapeutic agents which may slow the progression of CAVD (Fig. 1JOURNAL/cocar/04.03/00001573-202109000-00007/figure1/v/2021-08-04T080204Z/r/image-jpeg).

SUMMARY

This review summarizes the current knowledge on the association of Lp(a) with CAVD and ongoing studies of potential Lp(a)-lowering therapies. Based on the rate-limiting and causal role of Lp(a) in progression of CAVS, these therapies may represent novel pharmacotherapies in AS and inform the developing role of Lp(a) in the clinical management of CAVD.

Transvalvular Flow, Sex, and Survival After Valve Replacement Surgery in Patients With Severe Aortic Stenosis

BACKGROUND

The respective impacts of transvalvular flow, gradient, sex, and their interactions on mortality in patients with severe aortic stenosis undergoing surgical aortic valve replacement (AVR) are unknown.

OBJECTIVES

This study sought to compare the impact of pre-operative flow-gradient patterns on mortality after AVR and to examine whether there are sex differences.

METHODS

This study analyzed clinical, echocardiographic, and outcome data prospectively collected in 1,490 patients (544 women [37%]), with severe aortic stenosis and preserved left ventricular ejection fraction who underwent AVR.

RESULTS

In this cohort, 601 patients (40%) had normal flow (NF) with high gradient (HG), 405 (27%) NF with low gradient (LG), 246 (17%) paradoxical low flow (LF)/HG, and 238 (16%) LF/LG. During a median follow-up of 2.42 years (interquartile range: 1.04 to 4.29 years), 167 patients died. Patients with LF/HG exhibited the highest mortality after AVR (hazard ratio [HR]: 2.01; 95% confidence interval [CI]: 1.33 to 3.03; p < 0.01), which remained significant after multivariate adjustment (HR: 1.96; 95% CI: 1.29 to 2.98; p < 0.01). Both LF/LG and NF/LG patients had comparable outcome to NF/HG (p ≥ 0.47). Optimal thresholds of stroke volume index were obtained for men (40 ml/m²) and women (32 ml/m²). Using these sex-specific cutpoints, paradoxical LF was independently associated with increased mortality in both women (adjusted HR: 2.05; 95% CI: 1.21 to 3.47; p < 0.01) and men (adjusted HR: 1.54; 95% CI: 1.02 to 2.32; p = 0.042), whereas guidelines' threshold (35 ml/m²) does not.

CONCLUSIONS

Paradoxical LF/HG was associated with higher mortality following AVR, suggesting that a reduced flow is a marker of disease severity even in patients with HG aortic stenosis. Early surgical AVR (i.e., before gradient attains 40 mm Hg) might be preferable in these patients. Furthermore, the use of sex-specific thresholds (<40 ml/m² for men and <32 ml/m² for women) to define low-flow outperforms the guidelines' threshold of 35 ml/m² in risk stratification after AVR.

The benefit of fibrosa layer stripping technique during minimally invasive aortic valve replacement for calcified aortic valve stenosis-A randomized controlled trial

BACKGROUND

Fibrosa layer stripping (FLS) technique is a new approach to remove the calcified aortic valve. In this study, we aimed to assess the effectiveness of the FLS technique by comparing it with the conventional technique in minimally invasive aortic valve replacement (MIAVR).

METHODS

A prospective, single-center, randomized controlled trial was conducted at Beijing Anzhen Hospital. Seventy patients diagnosed with severe calcific aortic stenosis were randomly assigned to undergo FLS (n = 35) or conventional (n = 35) technique to debride calcified aortic valve. Preoperative profile, procedural parameters, and postoperative outcomes were analyzed.

RESULTS

No significant difference was observed in the preoperative profile between the two groups. Compared with the conventional technique, the FLS technique had a significantly higher indexed effective orifice area and lower mean gradient. Moreover, the FLS technique was associated with significantly reduced aortic cross-clamp time (41 [38-44] vs. 56 [51-60] min, p < .001), cardiopulmonary bypass (CPB) time (63 [56-69] vs. 81 [75-84] min, p < .001), and operative time (148 [141-156] vs. 173 [169-180] min, p < .001). Lastly, the length of intensive care unit stay (1.2 ± 0.4 vs. 1.5 ± 0.8 days, p = .041) and hospital stay (5.3 ± 0.6 vs. 6.0 ± 1.4 days, p = .020) was significantly reduced in the FLS group compared with those in the conventional group.

CONCLUSIONS

FLS technique is effective in removing calcified tissue during MIAVR and is associated with shorter cross-clamp time and CPB time, and better hemodynamic performance than the conventional technique.

Ultrastructural Pathology of Atherosclerosis, Calcific Aortic Valve Disease, and Bioprosthetic Heart Valve Degeneration: Commonalities and Differences

Atherosclerosis, calcific aortic valve disease (CAVD), and bioprosthetic heart valve degeneration (alternatively termed structural valve deterioration, SVD) represent three diseases affecting distinct components of the circulatory system and their substitutes, yet sharing multiple risk factors and commonly leading to the extraskeletal calcification. Whereas the histopathology of the mentioned disorders is well-described, their ultrastructural pathology is largely obscure due to the lack of appropriate investigation techniques. Employing an original method for sample preparation and the electron microscopy visualisation of calcified cardiovascular tissues, here we revisited the ultrastructural features of lipid retention, macrophage infiltration, intraplaque/intraleaflet haemorrhage, and calcification which are common or unique for the indicated types of cardiovascular disease. Atherosclerotic plaques were notable for the massive accumulation of lipids in the extracellular matrix (ECM), abundant macrophage content, and pronounced neovascularisation associated with blood leakage and calcium deposition. In contrast, CAVD and SVD generally did not require vasculo- or angiogenesis to occur, instead relying on fatigue-induced ECM degradation and the concurrent migration of immune cells. Unlike native tissues, bioprosthetic heart valves contained numerous specialised macrophages and were not capable of the regeneration that underscores ECM integrity as a pivotal factor for SVD prevention. While atherosclerosis, CAVD, and SVD show similar pathogenesis patterns, these disorders demonstrate considerable ultrastructural differences.

Autotaxin and Lipoprotein Metabolism in Calcific Aortic Valve Disease

Calcific aortic valve disease (CAVD) is a complex trait disorder characterized by calcific remodeling of leaflets. Genome-wide association (GWA) study and Mendelian randomization (MR) have highlighted that LPA, which encodes for apolipoprotein(a) [apo(a)], is causally associated with CAVD. Apo(a) is the protein component of Lp(a), a LDL-like particle, which transports oxidized phospholipids (OxPLs). Autotaxin (ATX), which is encoded by ENPP2, is a member of the ecto-nucleotidase family of enzymes, which is, however, a lysophospholipase. As such, ATX converts phospholipids into lysophosphatidic acid (LysoPA), a metabolite with potent and diverse biological properties. Studies have recently underlined that ATX is enriched in the Lp(a) lipid fraction. Functional experiments and data obtained in mouse models suggest that ATX mediates inflammation and mineralization of the aortic valve. Recent findings also indicate that epigenetically-driven processes lower the expression of phospholipid phosphatase 3 (PLPP3) and increased LysoPA signaling and inflammation in the aortic valve during CAVD. These recent data thus provide novel insights about how lipoproteins mediate the development of CAVD. Herein, we review the implication of lipoproteins in CAVD and examine the role of ATX in promoting the osteogenic transition of valve interstitial cells (VICs).

HIF-1α and VEGF: Immunohistochemical Profile and Possible Function in Human Aortic Valve Stenosis

Calcific aortic stenosis (CAS) is the most common valvular disease in Western countries. Histological findings in patients with CAS extremely resemble those of atherosclerosis and include accumulation and modification of lipoproteins, inflammation, extracellular matrix remodeling, and calcification. Angiogenesis is another prominent feature of CAS; however, there is only a limited amount of data available regarding the mechanisms behind the pathological neovascularization of a structure that is originally avascular. The present study aims to identify the molecular basis that regulates blood vessel growth in stenotic aortic valves, focusing on the role of HIF-1α and VEGF pathway. A total of 19 native degenerating aortic valves obtained at valve replacement surgery have been processed for Western blot, immunohistochemical, morphometric, and ultrastructural analyses. First, we have demonstrated the adverse ECM remodeling and the significant thickening of the leaflet also showing that HIF-1α and VEGF are significantly upregulated in the stenotic valves, are locally produced and colocalize with angiogenesis and areas of calcification. Next, we have characterized, for the first time to the best of our knowledge, the morphological features of the neovasculature evidencing the presence of intact blood vessels in close proximity to the mineralized zones. These results suggest that the complex structural remodeling of the matrix might reduce oxygen availability in the valve cusp contributing to the stabilization of HIF-1α that in turn induces a metabolic adaptation through the upregulation of VEGF and the formation of new blood vessels not only to overcome the hypoxic state but also to sustain the calcification process.

Molecular biology of calcific aortic valve disease: towards new pharmacological therapies

Calcific aortic valve disease (CAVD) is a chronic process leading to fibrosis and mineralization of the aortic valve. Investigations in the last several years have emphasized that key underlying molecular processes are involved in the pathogenesis of CAVD. In this regard, the processing of lipids and their retention has been underlined as an important mechanism that triggers inflammation. In turn, inflammation promotes/enhances the mineralization of valve interstitial cells, the main cellular component of the aortic valve. On the other hand, transformation of valve interstitial cells into myofibroblasts and osteoblast-like cells is determined by several signaling pathways having reciprocal cross-talks. In addition, the mineralization of the aortic valve has been shown to rely on ectonucleotidase and purinergic signaling. In this review, the authors have highlighted key molecular underpinnings of CAVD that may have significant relevance for the development of novel pharmaceutical therapies.