Statins for aortic stenosis

Unmet needs and knowledge gaps in aortic stenosis: A position paper from the Heart Valve Council of the French Society of Cardiology

Nowadays, valvular heart disease remains a significant challenge among cardiovascular diseases, affecting millions of people worldwide and exerting substantial pressure on healthcare systems. Within the spectrum of valvular heart disease, aortic stenosis is the most common valvular lesion in developed countries. Despite notable advances in understanding its pathophysiological processes, improved cardiovascular imaging techniques and expanding therapeutic options in recent years, there are still unmet needs and knowledge gaps regarding aortic stenosis pathophysiology, severity assessment, management and decision-making strategy. This review, prepared on behalf of the Heart Valve Council of the French Society of Cardiology, describes these gaps and future research perspectives to improve the outcome of patients with aortic stenosis.

Lipid Interventions in Aortic Valvular Disease

Aortic valve stenosis is the most common valvular disease in the elderly population. Presently, there is increasing evidence that aortic stenosis (AS) is an active process of lipid deposition, inflammation, fibrosis and calcium deposition. The pathogenesis of AS shares many similarities to that of atherosclerosis; therefore, it was hypothesized that certain lipid interventions could prevent or slow the progression of aortic valve stenosis. Despite the early enthusiasm that statins may slow the progression of AS, recent large clinical trials did not consistently demonstrate a decrease in the progression of AS. However, some researchers believe that statins may have a benefit early on in the disease process, where inflammation (and not calcification) is the predominant process, in contrast to severe or advanced AS, where calcification (and not inflammation) predominates. Positron emission tomography using 18F-fluorodeoxyglucose and 18F-sodium fluoride can demonstrate the relative contributions of valvular calcification and inflammation in AS, and thus this method might potentially be useful in providing the answer as to whether lipid interventions at the earlier stages of AS would be more effective in slowing the progression of the disease. Currently, there is a strong interest in recombinant apolipoprotein A-1 Milano and in the development of new pharmacological agents, targeting reduction of lipoprotein (a) levels and possibly reduction of the expression of lipoprotein-associated phospholipase A2, as potential means to slow the progression of aortic valvular stenosis.

Valvular heart disease: a primer for the clinical pharmacist

Valvular heart disease is a commonly encountered clinical condition that is not taught in most undergraduate and graduate pharmacy programs, leaving the practicing pharmacist without basic knowledge to expand on and subsequently apply to direct patient care. Unlike other areas of cardiology in which thousands of patients are recruited in many well-designed randomized clinical trials, data assessing treatments for valvular heart disease are limited and often consist of retrospective case series or observations. Our goal is to provide a basic overview of chronic valvular heart disease, with emphasis on describing the common conditions requiring surgery and the available options, as well as common pharmacologic therapies used in this patient population. Anomalies in valves can be broadly classified as stenosis and regurgitation. Depending on the valve and the type of anomaly, the impact on the cardiovascular system will vary. Understanding the hemodynamic consequences of aortic stenosis, aortic regurgitation, mitral stenosis, and mitral regurgitation is imperative to effectively counsel patients surrounding disease progression and self-monitoring, use of vasodilators, and prophylaxis for endocarditis and rheumatic fever. Further, patient characteristics factored into the choice of implanting either a bioprosthetic (tissue) or prosthetic (metal) valve encompass patient choice, life expectancy, and willingness or ability to accept lifelong anticoagulation therapy. The evolution of metal valves has resulted in newer generations under clinical study that have more laminar flow (minimizing interaction with blood products) and improved pyrolytic carbon (minimizing infection and interaction with blood products). Although antithrombotic therapy with warfarin is now mandatory in North America for all patients receiving metal valves, research is ongoing to assess the need with the most recent generation of valves.

Aortic balloon valvuloplasty--review and case series

Aortic balloon valvuloplasty (BAV) was initially devised in the 1980s as an alternative procedure to the surgical treatment of aortic stenosis, with the theory behind it being both minimally invasive as well as having a lower complication rate [Hara H, et al. Percutaneous balloon aortic valvuloplasty revisited: time for a renaissance? Circulation 2007 March;115(12):e334-8]. In practice however, the procedure was found to have a higher complication rate with only a modest haemodynamic improvement compared to the surgical approach. Most important of all it had an unacceptably high restenosis rate as a substitute for surgery [Otto CM, et al. 3-year outcome after balloon aortic balloon valvuloplasty: insights into prognosis of valvular aortic stenosis. Circulation 1994;89:642-50]. As a result, the procedure has fallen out of favour and has been abandoned at many health care facilities [Hara H, et al. Percutaneous balloon aortic valvuloplasty revisited: time for a renaissance? Circulation 2007 March;115(12):e334-8]. This article will review the management of patients with severe aortic stenosis that are unsuitable to undergo surgery.

Risk factors for progression of calcific aortic stenosis and potential therapeutic targets

Current thought regarding the progression of calcific aortic stenosis (AS) is presented. After summarizing contemporary ideas about AS pathogenesis, the present article examines the factors that may affect disease progression. Data indicate that this process may be accelerated by aortic valve structure, degree of valvular calcification, chronic renal insufficiency and cardiovascular risk factors such as diabetes and dyslipidemia. Finally, the present review discusses potential therapeutic targets to slow AS progression.

Insights Into Degenerative Aortic Valve Disease

Despite the dramatic decline of rheumatic heart disease over the past 5 decades, there has not been a concordant decline in the prevalence of valvular heart disease. Degenerative aortic valve disease (DAVD) has become the most common cause of valvular heart disease in the Western world, causing significant morbidity and mortality. No longer considered a benign consequence of aging, valve calcification is the result of an active process that, much like atherosclerotic vascular disease, is preceded by basement membrane disruption, inflammatory cell infiltration, and lipid deposition and is associated with diabetes, hypercholesterolemia, hypertension, and tobacco use. These realizations, in addition to pathological insights gained from emerging imaging modalities, have lead to the exploration of a variety of therapeutic interventions to delay or prevent the progression of DAVD. Inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, angiotensin-converting enzyme, and matrix metalloproteinase have all been studied as potential disease modifiers. Moreover, tissue engineering, aided by emerging stem cell technology, holds immense potential for the treatment of valvular heart disease as adjuncts to surgical interventions. Here we review the epidemiology and pathophysiology of DAVD, in addition to highlighting emerging therapeutic interventions for this growing problem.

Role of inflammation in nonrheumatic, regurgitant heart valve disease. A comparative, descriptive study regarding apolipoproteins and inflammatory cells in nonrheumatic heart valve disease

BACKGROUND

Nonrheumatic aortic stenosis is the predominant cause of heart valve surgery in the Western world. Aortic and mitral regurgitation account for a lesser amount of the heart valve surgery. During the 1990s, inflammatory cell infiltrates have been demonstrated in nonrheumatic stenotic aortic valves. These findings suggest an inflammatory component in the pathogenesis of nonrheumatic aortic valve stenosis. However, nonrheumatic regurgitant aortic and mitral valves have not been investigated in this respect. The aim of this study was to compare nonrheumatic regurgitant aortic and mitral valves with stenotic aortic valves regarding the presence of T lymphocytes, macrophages, apolipoprotein B, and apolipoprotein A-I.

METHODS

Valve specimens were obtained from 42 patients referred to hospital for surgery because of significant heart valve disease. From these patients, 29 aortic stenotic valves, 9 aortic regurgitant, and 6 mitral regurgitant valves, all nonrheumatic, were obtained for the study. Fourteen valves collected from subjects undergoing clinical/medicolegal autopsy were used as control. In order to identify mononuclear inflammatory cells and apolipoproteins, sections were investigated with immunohistochemical analyses and then categorized semiquantitatively.

RESULTS

Regurgitant and control valves showed a significantly lower degree of inflammatory cell infiltrate and a lower degree of apolipoprotein deposition as compared to stenotic aortic valves.

CONCLUSIONS

The signs of inflammation seen in nonrheumatic aortic stenosis are not prominent features in the nonrheumatic, regurgitant valves. This is consistent with the multi-factorial pathogenesis of these conditions.

A medical therapy for aortic valve sclerosis and aortic valve stenosis? Rationale of the ASSIST study (Asymptomatic aortic Sclerosis/Stenosis: Influence of STatins): a large, observational, prospective, multicenter study of the Italian Society of Cardiovascular Echography

Progression of sclerosis and stenosis is substantially unpredictable in the individual patient: in some cases it is very slow, in others it is accelerated. In addition, different patterns of progression (linear and non-linear) are possible. It has been suggested that the aortic valve lesion can be considered a form within the spectrum of the same atherosclerotic disease. In this context it seemed reasonable to hypothesize that targeted medical therapy could retard the progression of the disease. In particular HMG-CoA reductase inhibitors (statins) and angiotensin-converting enzyme inhibitors have been tested. The first experimental and clinical studies are now available, even though they are not conclusive to date. Large, prospective, randomized trials are ideally needed, but they are quite difficult, if not even impossible, to realize in practice. The ASSIST study (Asymptomatic aortic Sclerosis/Stenosis: Influence of STatins) of the Italian Society of Cardiovascular Echography aims to create a large, prospective, observational investigation, involving many centers of echocardiography and thousands of patients, in order to provide from the real clinical world at least some of the answers to this unsolved question.

C-reactive protein in aortic valve disease

Aortic Valve Disease, includes a range of disorder severity from mild leaflet thickening without valve obstruction, "aortic sclerosis", to severe calcified aortic stenosis. It is a slowly progressive active process of valve modification similar atherosclerosis for cardiovascular risk factors, lipoprotein deposition, chronic inflammation, and calcification. Systemic signs of inflammation, as wall and serum CRP, similar to those found in atherosclerosis, are present in patients with degenerative aortic valve stenosis and may be expression of a common disease, useful in monitoring of stenosis progression.

C-reactive protein in degenerative aortic valve stenosis

Degenerative aortic valve stenosis includes a range of disorder severity from mild leaflet thickening without valve obstruction, "aortic sclerosis", to severe calcified aortic stenosis. It is a slowly progressive active process of valve modification similar to atherosclerosis for cardiovascular risk factors, lipoprotein deposition, chronic inflammation, and calcification. Systemic signs of inflammation, as wall and serum C-reactive protein, similar to those found in atherosclerosis, are present in patients with degenerative aortic valve stenosis and may be expression of a common disease, useful in monitoring of stenosis progression.

Statin therapy of calcific aortic stenosis: hype or hope?

Calcific aortic stenosis, with a prevalence of 3-9%, is the most frequent heart valve disease and the main cause for valve replacement in patients over 60 years of age. Once thought to be caused by a passive calcium precipitate within the aortic valve leaflets, there is now increasing evidence that development and progression of calcific aortic valve disease may be triggered by underlying genetic and cardiovascular risk factors, and is regulated by an active cellular process involving inflammatory pathways. Targeted drug therapy to prevent the progression of calcific aortic valve disease should ideally be based on the knowledge of risk factors and the molecular pathogenesis of the disease. Conflicting data exists on the potency of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (i.e. statins) to influence both risk factors and inflammatory pathways by lowering lipid levels and exerting anti-inflammatory properties, respectively. In this review, various aspects of the molecular pathogenesis of calcific aortic stenosis will be summarized and connected with recent experimental and clinical studies that address the potential benefit of the targeted drug therapy by statins in order to prevent the progression of the disease.