Inverse association between bone mineral density and risk of aortic stenosis in men and women in EPIC–Norfolk prospective study

Calcific aortic valve disease: from molecular and cellular mechanisms to medical therapy

Calcific aortic valve disease (CAVD) is a highly prevalent condition that comprises a disease continuum, ranging from microscopic changes to profound fibro-calcific leaflet remodelling, culminating in aortic stenosis, heart failure, and ultimately premature death. Traditional risk factors, such as hypercholesterolaemia and (systolic) hypertension, are shared among atherosclerotic cardiovascular disease and CAVD, yet the molecular and cellular mechanisms differ markedly. Statin-induced low-density lipoprotein cholesterol lowering, a remedy highly effective for secondary prevention of atherosclerotic cardiovascular disease, consistently failed to impact CAVD progression or to improve patient outcomes. However, recently completed phase II trials provide hope that pharmaceutical tactics directed at other targets implicated in CAVD pathogenesis offer an avenue to alter the course of the disease non-invasively. Herein, we delineate key players of CAVD pathobiology, outline mechanisms that entail compromised endothelial barrier function, and promote lipid homing, immune-cell infiltration, and deranged phospho-calcium metabolism that collectively perpetuate a pro-inflammatory/pro-osteogenic milieu in which valvular interstitial cells increasingly adopt myofibro-/osteoblast-like properties, thereby fostering fibro-calcific leaflet remodelling and eventually resulting in left ventricular outflow obstruction. We provide a glimpse into the most promising targets on the horizon, including lipoprotein(a), mineral-binding matrix Gla protein, soluble guanylate cyclase, dipeptidyl peptidase-4 as well as candidates involved in regulating phospho-calcium metabolism and valvular angiotensin II synthesis and ultimately discuss their potential for a future therapy of this insidious disease.

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.

The role of inflammation and metabolic risk factors in the pathogenesis of calcific aortic valve stenosis

Given the epidemiologic increase of aged population in the world, aortic stenosis (AS) represents now the most common valvular heart disease in industrialized countries. It is a very challenging disease, representing an important cause of morbidity, hospitalization and death in the elderly population. It is widely recognized that AS is the result of a very complex active process, driven by inflammation and involving multifactorial pathological mechanisms promoting valvular calcification and valvular bone deposition. Several evidence suggest that epicardial adipose tissue (EAT), the visceral fat depot of the heart, represents a direct source of cytokines and could mediate the deleterious effects of systemic inflammation on the myocardium. Importantly, obesity and metabolic disorders are associated with chronic systemic inflammation leading to a significant increase of EAT amount and to a pro-inflammatory phenotypic shift of this fat depot. It has been hypothesized that the EAT inflammatory state can influence the structure and function of the heart, thus contributing to the pathogenesis of several cardiac diseases, including calcific AS. The current review will discuss the recently discovered mechanisms involved in the pathogenesis of AS, with particular attention to the role of inflammation, metabolic risk factors and pro-fibrotic and pro-osteogenic signal pathways promoting the onset and progression of the disease. Moreover, it will be explored the potential role of EAT in the AS pathophysiology.

Current Evidence and Future Perspectives on Pharmacological Treatment of Calcific Aortic Valve Stenosis

Calcific aortic valve stenosis (CAVS), the most common heart valve disease, is characterized by the slow progressive fibro-calcific remodeling of the valve leaflets, leading to progressive obstruction to the blood flow. CAVS is an increasing health care burden and the development of an effective medical treatment is a major medical need. To date, no effective pharmacological therapies have proven to halt or delay its progression to the severe symptomatic stage and aortic valve replacement represents the only available option to improve clinical outcomes and to increase survival. In the present report, the current knowledge and latest advances in the medical management of patients with CAVS are summarized, placing emphasis on lipid-lowering agents, vasoactive drugs, and anti-calcific treatments. In addition, novel potential therapeutic targets recently identified and currently under investigation are reported.

Calcification of Cardiac Valves in Metabolic Bone Disease: An Updated Review of Clinical Studies

Epidemiological and clinical data have suggested the existence of a relationship between cardiovascular diseases and metabolic bone disease. Several studies have demonstrated that heart valve calcification presents substantial similarities with that of bone. Literature data indicate that there are many active processes which promote osteogenesis and loss of mineralization inhibitors that lead to the deposition of extracellular matrix and proteins of bone tissue in cardiac valves. This review aimed to synthesize the available data in order to allow a better understanding of the relationship between osteoporosis or other metabolic bone diseases, such as primary hyperparathyroidism, and valvular calcification in humans. Electronic databases of Pubmed-Medline, Cochrane Library, and SCOPUS from inception to March 31, 2019 were searched. The full set of the articles potentially eligible were carefully assessed and reviewed. Finally, 23 studies were eligible and included in the systematic review. The majority of studies reported that osteoporosis and/or osteopenia were independent risk factors for valvular calcifications, even after adjusting for common cardiovascular risk factors. This suggests that this relationship is not only due to the presence of common cardiovascular risk factors but rather to underlying biological factors that connect them. Instead, regarding the association between primary hyperparathyroidism and valve calcification, conflicting data were found in the literature. To sum up, most of the literature data confirm that cardiac valve calcification processes are strongly influenced by alterations in bone metabolism. In particular, the patients with osteoporosis or primary hyperparathyroidism have an acceleration in the process of valvular calcification. Additional studies are needed to specifically address the mechanisms by which metabolic bone diseases could influence cardiac valve calcification.

ApoB/ApoA-I Ratio is Associated With Faster Hemodynamic Progression of Aortic Stenosis: Results From the PROGRESSA (Metabolic Determinants of the Progression of Aortic Stenosis) Study

BACKGROUND

Previous studies reported that middle-aged patients with atherogenic lipoprotein-lipid profile exhibit faster progression of aortic valve stenosis (AS). The ratio of apolipoprotein B/apolipoprotein A-I (apoB/apoA-I) reflects the balance between atherogenic and anti-atherogenic lipoproteins. The aim of this study was to examine the association between apoB/apoA-I ratio and AS hemodynamic progression and to determine whether this association varies according to age.

METHODS AND RESULTS

A total of 159 patients (66±13 years, 73% men) with AS were prospectively recruited in the PROGRESSA (Metabolic Determinants of the Progression of Aortic Stenosis) study. Hemodynamic progression of AS was determined by the change in peak aortic jet velocity (V_peak) measured by Doppler-echocardiography between baseline and 2-year follow-up. Patients in the top tertile of apoB/apoA-I ratio (≥0.62) had a faster progression rate of AS compared with those in the bottom/mid tertiles (V_peak progression: 0.30 [0.09-0.49] versus 0.16 [0.01-0.36] m/s, P=0.02). There was a significant interaction (P=0.007) between apoB/apoA-I ratio and age. Among younger patients (ie, aged <70 years; median value of the cohort), those in the top tertile of apoB/apoA-I ratio had a 3.4-fold faster AS progression compared with those in the bottom/mid tertiles (V_peak progression: 0.34 [0.13-0.69] versus 0.10 [-0.03-0.31] m/s, P=0.002), whereas there was no significant difference between tertiles in the subgroup of older patients (P=0.83). After comprehensive adjustment, higher apoB/apoA-I ratio was significantly associated with faster AS progression in the subset of younger patients (all, standardized β≥0.36; P≤0.01).

CONCLUSIONS

Higher apoB/apoA-I ratio is significantly associated with faster hemodynamic progression of AS in the younger patients. These findings suggest that atherogenic lipid factors may play a crucial role in the pathogenesis of AS in younger patients, but may be are less important in older patients.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01679431.

Relationship of bone mineral density with valvular and annular calcification in community-dwelling older people: The Cardiovascular Health Study

Associations between bone mineral density and aortic valvular, aortic annular, and mitral annular calcification were investigated in a cross-sectional analysis of a population-based cohort of 1497 older adults. Although there was no association between continuous bone mineral density and outcomes, a significant association between osteoporosis and aortic valvular calcification in men was found.

INTRODUCTION

The process of cardiac calcification bears a resemblance to skeletal bone metabolism and its regulation. Experimental studies suggest that bone mineral density (BMD) and valvular calcification may be reciprocally related, but epidemiologic data are sparse.

METHODS

We tested the hypothesis that BMD of the total hip and femoral neck measured by dual-energy X-ray absorptiometry (DXA) is inversely associated with prevalence of three echocardiographic measures of cardiac calcification in a cross-sectional analysis of 1497 older adults from the Cardiovascular Health Study. The adjusted association of BMD with aortic valve calcification (AVC), aortic annular calcification (AAC), and mitral annular calcification (MAC) was assessed with relative risk (RR) regression.

RESULTS

Mean (SD) age was 76.2 (4.8) years; 58% were women. Cardiac calcification was highly prevalent in women and men: AVC, 59.5 and 71.0%; AAC 45.1 and 46.7%; MAC 42.8 and 39.5%, respectively. After limited and full adjustment for potential confounders, no statistically significant associations were detected between continuous BMD at either site and the three measures of calcification. Assessment of WHO BMD categories revealed a significant association between osteoporosis at the total hip and AVC in men (adjusted RR compared with normal BMD = 1.24 (1.01-1.53)). In graded sensitivity analyses, there were apparent inverse associations between femoral neck BMD and AVC with stenosis in men, and femoral neck BMD and moderate/severe MAC in women, but these were not significant.

CONCLUSION

These findings support further investigation of the sex-specific relationships between low BMD and cardiac calcification, and whether processes linking the two could be targeted for therapeutic ends.