The Pathogenesis and treatment of the valvulopathy of aortic stenosis: Beyond the SEAS

Prioritization of Candidate Biomarkers for Degenerative Aortic Stenosis through a Systems Biology-Based In-Silico Approach

Degenerative aortic stenosis is the most common valve disease in the elderly and is usually confirmed at an advanced stage when the only treatment is surgery. This work is focused on the study of previously defined biomarkers through systems biology and artificial neuronal networks to understand their potential role within aortic stenosis. The goal was generating a molecular panel of biomarkers to ensure an accurate diagnosis, risk stratification, and follow-up of aortic stenosis patients. We used in silico studies to combine and re-analyze the results of our previous studies and, with information from multiple databases, established a mathematical model. After this, we prioritized two proteins related to endoplasmic reticulum stress, thrombospondin-1 and endoplasmin, which have not been previously validated as markers for aortic stenosis, and analyzed them in a cell model and in plasma from human subjects. Large-scale bioinformatics tools allow us to extract the most significant results after using high throughput analytical techniques. Our results could help to prevent the development of aortic stenosis and open the possibility of a future strategy based on more specific therapies.

Cardiovascular Effects and Molecular Mechanisms of Bisphenol A and Its Metabolite MBP in Zebrafish

The plastic monomer bisphenol A (BPA) is one of the highest production volume chemicals in the world and is frequently detected in wildlife and humans, particularly children. BPA has been associated with numerous adverse health outcomes relating to its estrogenic and other hormonal properties, but direct causal links are unclear in humans and animal models. Here we simulated measured (1×) and predicted worst-case (10× ) maximum fetal exposures for BPA, or equivalent concentrations of its metabolite MBP, using fluorescent reporter embryo-larval zebrafish, capable of quantifying Estrogen Response Element (ERE) activation throughout the body. Heart valves were primary sites for ERE activation by BPA and MBP, and transcriptomic analysis of microdissected heart tissues showed that both chemicals targeted several molecular pathways constituting biomarkers for calcific aortic valve disease (CAVD), including extra-cellular matrix (ECM) alteration. ECM collagen deficiency and impact on heart valve structural integrity were confirmed by histopathology for high-level MBP exposure, and structural defects (abnormal curvature) of the atrio-ventricular valves corresponded with impaired cardiovascular function (reduced ventricular beat rate and blood flow). Our results are the first to demonstrate plausible mechanistic links between ERE activation in the heart valves by BPA's reactive metabolite MBP and the development of valvular-cardiovascular disease states.

New classification of geometric ventricular patterns in severe aortic stenosis: Could it be clinically useful?

BACKGROUND

In severe aortic stenosis, different left ventricle (LV) remodeling patterns as a response to pressure overload have distinct hemodynamic profiles, cardiac function, and outcomes. The most common classification considers LV relative wall thickness and LV mass index to create 4 different groups. A new classification including also end-diastolic volume index has been recently proposed.

AIM

To describe the prevalence of the newly identified remodeling patterns in patients with severe aortic stenosis and to evaluate their clinical relevance according to symptoms.

METHODS

We analyzed 286 consecutive patients with isolated severe aortic stenosis. Current guidelines were used for echocardiographic evaluation. Symptoms were defined as the presence of angina, syncope, or NYHA class III-IV.

RESULTS

The mean age was 75 ± 9 years, 156 patients (54%) were men, while 158 (55%) were symptomatic. According to the new classification, the most frequent remodeling pattern was concentric hypertrophy (57.3%), followed by mixed (18.9%) and dilated hypertrophy (8.4%). There were no patients with eccentric remodeling; only 4 patients had a normalLV geometry. Symptomatic patients showed significantly more mixed hypertrophy (P < .05), while the difference regarding the prevalence of the other patterns was not statistically significant. When we analyzed the distribution of the classic 4 patterns stratified by the presence of symptoms, however, we did not find a significant difference (P = .157).

CONCLUSIONS

The new classification had refined the description of different cardiac geometric phenotypes that develop as a response to pressure overload. It might be superior to the classic 4 patterns in terms of association with symptoms.

Increased hsCRP is associated with higher risk of aortic valve replacement in patients with aortic stenosis

Objective To investigate relations between inflammation and aortic valve stenosis (AS) by measuring high-sensitivity C-reactive protein, at baseline (hsCRP0) and after 1 year (hsCRP1) and exploring associations with aortic valve replacement (AVR). Design We examined 1423 patients from the Simvastatin and Ezetimibe in Aortic Stenosis study. Results During first year of treatment, hsCRP was reduced both in patients later receiving AVR (2.3 [0.9-4.9] to 1.8 [0.8-5.4] mg/l, p < 0.001) and not receiving AVR (1.90 [0.90-4.10] to 1.3 [0.6-2.9] mg/l, p < 0.001). In Cox-regression analyses, hsCRP1 predicted later AVR (HR = 1.17, p < 0.001) independently of hsCRP0 (HR = 0.96, p = 0.33), aortic valve area (AVA) and other risk factors. A higher rate of AVR was observed in the group with high hsCRP0 and an increase during the first year (AVRhighCRP0CRP1inc = 47.3% versus AVRhighCRP0CRP1dec = 27.5%, p < 0.01). The prognostic benefit of a 1-year reduction in hsCRP was larger in patients with high versus low hsCRP0 eliminating the difference in incidence of AVR between high versus low hsCRP0 (AVRhighCRP0CRP1dec = 27.5% versus AVRlowCRP0CRP1dec = 25.8%, p = 0.66) in patients with reduced hsCRP during the first year. Conclusions High hsCRP1 or an increase in hsCRP during the first year of follow-up predicted later AVR independently of AVA, age, gender and other risk factors, although no significant improvement in C-statistics was observed.

Cells and extracellular matrix interplay in cardiac valve disease: because age matters

Cardiovascular aging is a physiological process affecting all components of the heart. Despite the interest and experimental effort lavished on aging of cardiac cells, increasing evidence is pointing at the pivotal role of extracellular matrix (ECM) in cardiac aging. Structural and molecular changes in ECM composition during aging are at the root of significant functional modifications at the level of cardiac valve apparatus. Indeed, calcification or myxomatous degeneration of cardiac valves and their functional impairment can all be explained in light of age-related ECM alterations and the reciprocal interplay between altered ECM and cellular elements populating the leaflet, namely valvular interstitial cells and valvular endothelial cells, is additionally affecting valve function with striking reflexes on the clinical scenario. The initial experimental findings on this argument are underlining the need for a more comprehensive understanding on the biological mechanisms underlying ECM aging and remodeling as potentially constituting a pharmacological therapeutic target or a basis to improve existing prosthetic devices and treatment options. Given the lack of systematic knowledge on this topic, this review will focus on the ECM changes that occur during aging and on their clinical translational relevance and implications in the bedside scenario.

Left ventricular remodelling in aortic stenosis

Aortic stenosis (AS) is a progressive condition associated with high mortality if not treated. The hemodynamic effects of AS have serious implications for the left ventricle. In this review, we describe the responses of the left ventricle to AS by highlighting the process of adaptive remodelling, which begins as a beneficial compensatory mechanism but ultimately transitions to a maladaptive process with potentially irreversible consequences. We discuss the impact of left ventricular (LV) remodelling on diastolic and systolic function and on the development of symptoms. In addition, we review the adverse consequences of maladaptive LV remodelling on clinical outcomes before and after aortic valve replacement. The relative irreversibility of maladaptive remodelling and the clear relationship between its progression and clinical outcomes suggest a need to incorporate measures of LV performance beyond simply systolic function when deciding on the timing of valve replacement.

Characterization of porcine aortic valvular interstitial cell 'calcified' nodules

Valve interstitial cells populate aortic valve cusps and have been implicated in aortic valve calcification. Here we investigate a common in vitro model for aortic valve calcification by characterizing nodule formation in porcine aortic valve interstitial cells (PAVICs) cultured in osteogenic (OST) medium supplemented with transforming growth factor beta 1 (TGF-β1). Using a combination of materials science and biological techniques, we investigate the relevance of PAVICs nodules in modeling the mineralised material produced in calcified aortic valve disease. PAVICs were grown in OST medium supplemented with TGF-β1 (OST+TGF-β1) or basal (CTL) medium for up to 21 days. Murine calvarial osteoblasts (MOBs) were grown in OST medium for 28 days as a known mineralizing model for comparison. PAVICs grown in OST+TGF-β1 produced nodular structures staining positive for calcium content; however, micro-Raman spectroscopy allowed live, noninvasive imaging that showed an absence of mineralized material, which was readily identified in nodules formed by MOBs and has been identified in human valves. Gene expression analysis, immunostaining, and transmission electron microscopy imaging revealed that PAVICs grown in OST+TGF-β1 medium produced abundant extracellular matrix via the upregulation of the gene for Type I Collagen. PAVICs, nevertheless, did not appear to further transdifferentiate to osteoblasts. Our results demonstrate that 'calcified' nodules formed from PAVICs grown in OST+TGF-β1 medium do not mineralize after 21 days in culture, but rather they express a myofibroblast-like phenotype and produce a collagen-rich extracellular matrix. This study clarifies further the role of PAVICs as a model of calcification of the human aortic valve.

Associations of LV hypertrophy with prevalent and incident valve calcification: Multi-Ethnic Study of Atherosclerosis

OBJECTIVES

The aim of this study was to evaluate the relationship between percentage of predicted left ventricular mass (%PredLVM) and valve calcification in the MESA (Multi-Ethnic Study of Atherosclerosis) study.

BACKGROUND

Cardiac valve calcification has been associated with left ventricular hypertrophy (LVH), which portends cardiovascular events. However, this relationship and its mediators are poorly understood.

METHODS

The MESA study is a longitudinal cohort study of men and women 45 to 84 years of age without clinical cardiovascular disease in whom serial cardiac magnetic resonance and computed tomography imaging were performed. The relationships between baseline %PredLVM and the prevalence, severity, and incidence of aortic valve (AVC) and mitral annulus calcification (MAC) were determined by regression modeling.

RESULTS

Prevalent AVC was observed in 630, and MAC was observed in 442 of 5,042 subjects (median 55.9 and 71.1 Agatston units, respectively). After adjustment for age, sex, body mass index (BMI), ethnicity, socioeconomic status, physical activity, diabetes, cholesterol levels, blood pressure, smoking, kidney function, serum lipids, and antihypertensive and statin medications, %PredLVM was associated with prevalent AVC (odds ratio [OR]: 1.18/SD increase in %PredLVM [95% confidence interval (CI): 1.08 to 1.30]; p = 0.0004) and MAC (OR: 1.18 [95% CI: 1.06 to 1.32]; p = 0.002). Similarly, %PredLVM was associated with increased severity of prevalent AVC (risk difference = 0.26 [95% CI: 0.15 to 0.38]; p < 0.0001) and MAC (risk difference = 0.20 [95% CI: 0.03 to 0.37]; p = 0.02). During follow-up (mean 2.4 ± 0.9 years), 153 subjects (4%) developed AVC, and 198 (5%) developed MAC. The %PredLVM was associated with incident AVC (OR: 1.24 [95% CI: 1.04 to 1.47]; p = 0.02) and MAC (OR: 1.18 [95% CI: 1.01 to 1.40]; p = 0.04). Further adjustment for inflammatory markers and coronary artery calcification did not attenuate these associations. Specifically, concentric LVH most strongly predicted incident valve calcification.

CONCLUSIONS

Within the MESA cohort, LVH was associated with prevalence, severity, and incidence of valve calcification independent of hypertension and other identified confounders.

Aortic stenosis and vascular calcifications in alkaptonuria

Alkaptonuria is a rare metabolic disorder of tyrosine catabolism in which homogentisic acid (HGA) accumulates and is deposited throughout the spine, large joints, cardiovascular system, and various tissues throughout the body. In the cardiovascular system, pigment deposition has been described in the heart valves, endocardium, pericardium, aortic intima and coronary arteries. The prevalence of cardiovascular disease in patients with alkaptonuria varies in previous reports. We present a series of 76 consecutive adult patients with alkaptonuria who underwent transthoracic echocardiography between 2000 and 2009. A subgroup of 40 patients enrolled in a treatment study underwent non-contrast CT scans and these were assessed for vascular calcifications. Six of the 76 patients had aortic valve replacement. In the remaining 70 patients, 12 patients had aortic sclerosis and 7 patients had aortic stenosis. Unlike degenerative aortic valve disease, we found no correlation with standard cardiac risk factors. There was a modest association between the severity of aortic valve disease and joint involvement, however, we saw no correlation with urine HGA levels. Vascular calcifications were seen in the coronaries, cardiac valves, aortic root, descending aorta and iliac arteries. These findings suggest an important role for echocardiographic screening of alkaptonuria patients to detect valvular heart disease and cardiac CT to detect coronary artery calcifications.

Balloon Aortic Valvuloplasty in the Transcatheter Aortic Valve Replacement Era

Initial enthusiasm for balloon aortic valvuloplasty (BAV) as an alternative to surgical aortic valve replacement waned because of the perceived failure of the procedure to alter the natural history of calcific severe aortic valve stenosis (AS) and significant initial procedural morbidity. Despite technical and procedural advances, BAV has been reserved as a palliative procedure for patients who cannot undergo valve replacement or as a bridge to surgery in hemodynamically unstable patients. This article reviews the indications, technical aspects, and outcomes of BAV for calcific AS and discusses the current role of BAV in the era of transcatheter aortic valve replacement.

Progress in perioperative medicine: focus on statins

Beyond cholesterol reduction, statins have multiple beneficial influences on vascular endothelial function, atherosclerotic plaque stability, inflammation, and thrombosis. These favorable pleiotropic effects may be the basis for their perioperative risk reduction in cardiothoracic and vascular procedures. The published evidence suggests that statins offer significant outcome benefits throughout perioperative practice. Because statin therapy significantly reduces the perioperative risk for patients undergoing cardiovascular procedures, they already are recommended in published guidelines. Beyond cardiac risk reduction, statin therapy also may protect the brain and the kidney in the perioperative setting, both in cardiac and vascular surgery. The pleiotropic effects of statins also appear to have therapeutic roles in the progression of valve disease, sepsis, and venous thrombosis. Further trials are required to provide data to drive their safe and comprehensive perioperative application for optimal patient outcome both in the short term and the long term. Because there are multiple randomized trials currently in progress throughout perioperative medicine, it is very likely that the indications for statins will be expanded significantly.