New concepts in valvular hemodynamics: implications for diagnosis and treatment of aortic stenosis

Practice guidance for stress echocardiography

Stress echocardiography has been one of the most promising methods for the diagnosis of ischemic heart disease, hypertrophic cardiomyopathy, and pulmonary hypertension. The Japanese Society of Echocardiography produced practical guidance for the implementation of stress echocardiography in 2018. At that time, stress echocardiography was not yet widely disseminated in Japan; therefore, the 2018 practical guidance for the implementation of stress echocardiography included a report on stress echocardiography and a specific protocol to promote its use at many institutions in Japan in the future. And now, an era of renewed interest and enthusiasm surrounding the diagnosis and treatment of valvular heart disease and heart failure with preserved ejection fraction (HFpEF) has come, which are driven by emerging trans-catheter procedures and new recommended guideline-directed medical therapy. Based on the continued evidence of stress echocardiography, the new practical guideline that describes the safe and effective methodology of stress echocardiography is now created by the Guideline Development Committee of the Japanese Society of Echocardiography and is designed to expand the use of stress echocardiography for valvular heart disease and HFpEF, as well as ischemic heart disease, hypertrophic cardiomyopathy, and pulmonary hypertension. The readers are encouraged to perform stress echocardiography which will enhance the diagnosis and management of these patients.

Stress echocardiography in valvular heart disease

Valvular heart disease (VHD) has been a significant health problem, particularly in developed countries, in relation to the aging population. Recent developments in the management of VHD require a more accurate assessment of disease severity to determine the need for transcatheter interventions or open heart surgery. Stress echocardiography is a crucial imaging modality for identifying the underlying pathology of VHD. Optimal administration of exercise or intravenous drugs may reveal hemodynamic abnormalities under stress without posing an invasive risk. Therefore, the implementation of stress echocardiography is recommended for determining interventional indications and risk stratification in mitral regurgitation and aortic stenosis. In addition, recent evidence has accumulated regarding the usefulness of stress echocardiography in various conditions including mitral stenosis, aortic regurgitation, and post-interventional VHD. Here, we summarize the current evidence and future perspectives on stress echocardiography in VHD.

Severe mitral stenosis masquerading as cardiogenic shock successfully managed with extracorporeal membrane oxygenation and percutaneous mitral commissurotomy: a case report

Background

Rheumatic fever is still a major cause of mitral valve (MV) stenosis in the developing world. Few patients with critical rheumatic MV stenosis can present with acute cardiogenic shock (CS) that requires urgent treatment with circulatory support and definitive valvular repair or replacement.

Case summary

A 37-year-old gentleman was admitted with heart failure, CS Society for Cardiovascular Angiography and Interventions D, and atrial fibrillation with a rapid ventricular response. He had no prior medical history. He had multiple organ failures and required intubation, two DC shocks of 200 joules without haemodynamic improvement, continuous renal replacement therapy, and medical and mechanical circulatory support using extracorporeal membrane oxygenation (ECMO). His echocardiography showed severe rheumatic mitral stenosis (mitral valve area 2D of 0.7 cm2, mean diastolic gradient of 17 mmHg, Wilkins score 7). His Society of Thoracic Surgery score and EuroScore were 50.1% and 12.1%, respectively. Thus, a percutaneous transcatheter mitral commissurotomy (PTMC) was decided as the definitive treatment in a multidisciplinary team meeting. Following the procedure, the patient's circulatory support was gradually weaned off, and he was successfully extubated with a marked improvement in his renal functions. The patient achieved a complete recovery without any long-term sequelae.

Discussion

Cardiogenic shock related to severe rheumatic MV stenosis requires multidisciplinary team management with prompt diagnosis, initiation of the most appropriate mechanical support device (e.g. ECMO or tandem heart), and relief of the MV obstruction. Percutaneous transcatheter mitral commissurotomy can be the preferred option in this setting if the valve is pliable.

An ultrasound-exclusive non-invasive computational diagnostic framework for personalized cardiology of aortic valve stenosis

Aortic stenosis (AS) is an acute and chronic cardiovascular disease and If left untreated, 50% of these patients will die within two years of developing symptoms. AS is characterized as the stiffening of the aortic valve leaflets which restricts their motion and prevents the proper opening under transvalvular pressure. Assessments of the valve dynamics, if available, would provide valuable information about the patient's state of cardiac deterioration as well as heart recovery and can have incredible impacts on patient care, planning interventions and making critical clinical decisions with life-threatening risks. Despite remarkable advancements in medical imaging, there are no clinical tools available to quantify valve dynamics invasively or noninvasively. In this study, we developed a highly innovative ultrasound-based non-invasive computational framework that can function as a diagnostic tool to assess valve dynamics (e.g. transient 3-D distribution of stress and displacement, 3-D deformed shape of leaflets, geometric orifice area and angular positions of leaflets) for patients with AS at no risk to the patients. Such a diagnostic tool considers the local valve dynamics and the global circulatory system to provide a platform for testing the intervention scenarios and evaluating their effects. We used clinical data of 12 patients with AS not only to validate the proposed framework but also to demonstrate its diagnostic abilities by providing novel analyses and interpretations of clinical data in both pre and post intervention states. We used transthoracic echocardiogram (TTE) data for the developments and transesophageal echocardiography (TEE) data for validation.

Comparison of hemodynamics in biological surgical aortic valve replacement and transcatheter aortic valve implantation: An in-silico study

OBJECTIVES

In aortic valve replacement (AVR), the treatment strategy as well as the model and size of the implanted prosthesis have a major impact on the postoperative hemodynamics and thus on the clinical outcome. Preinterventional prediction of the hemodynamics could support the treatment decision. Therefore, we performed paired virtual treatment with transcatheter AVR (TAVI) and biological surgical AVR (SAVR) and compared hemodynamic outcomes using numerical simulations.

METHODS

10 patients with severe aortic stenosis (AS) undergoing TAVI were virtually treated with both biological SAVR and TAVI to compare post-interventional hemodynamics using numerical simulations of peak-systolic flow. Virtual treatment procedure was done using an in-house developed tool based on position-based dynamics methodology, which was applied to the patient's anatomy including LVOT, aortic root and aorta. Geometries were automatically segmented from dynamic CT-scans and patient-specific flow rates were calculated by volumetric analysis of the left ventricle. Hemodynamics were assessed using the STAR CCM+ software by solving the RANS equations.

RESULTS

Virtual treatment with TAVI resulted in realistic hemodynamics comparable to echocardiographic measurements (median difference in transvalvular pressure gradient [TPG]: -0.33 mm Hg). Virtual TAVI and SAVR showed similar hemodynamic functions with a mean TPG with standard deviation of 8.45 ± 4.60 mm Hg in TAVI and 6.66 ± 3.79 mm Hg in SAVR (p = 0.03) while max. Wall shear stress being 12.6 ± 4.59 vs. 10.2 ± 4.42 Pa (p = 0.001).

CONCLUSIONS

Using the presented method for virtual treatment of AS, we were able to reliably predict post-interventional hemodynamics. TAVI and SAVR show similar hemodynamics in a pairwise comparison.

New Evidence About Aortic Valve Stenosis and Cardiovascular Hemodynamics

Aortic stenosis (AS) is the most common degenerative valvular disease in western word. In patients with severe AS, small changes in aortic valve area can lead to large changes in hemodynamics. The correct understanding of cardiac hemodynamics and its interaction with vascular function is of paramount importance for correct identification of severe AS and to plan effective strategies for its treatment. In the current review with highlight the importance of pressure recovery phenomenon and valvular arterial impedance as novel tools in the evaluation of patients with aortic stenosis.

Valvulo-Arterial Impedance and Dimensionless Index for Risk Stratifying Patients With Severe Aortic Stenosis

The hemodynamic effects of aortic stenosis (AS) consist of increased left ventricular (LV) afterload, reduced myocardial compliance, and increased myocardial workload. The LV in AS patients faces a double load: valvular and arterial loads. As such, the presence of symptoms and occurrence of adverse events in AS should better correlate with calculating the global burden faced by the LV in addition to the transvalvular gradient and aortic valve area (AVA). The valvulo-arterial impedance (Zva) is a useful parameter providing an estimate of the global LV hemodynamic load that results from the summation of the valvular and vascular loads. In addition to calculating the global LV afterload, it is paramount to estimate the stenosis severity accurately. In clinical practice, the management of low-flow low-gradient (LF-LG) severe AS with preserved LV ejection fraction requires careful confirmation of stenosis severity. In addition to the Zva, the dimensionless index (DI) is a very useful parameter to express the size of the effective valvular area as a proportion of the cross-section area of the left ventricular outlet tract velocity-time integral (LVOT-VTI) to that of the aortic valve jet (dimensionless velocity ratio). The DI is calculated by a ratio of the sub-valvular velocity obtained by pulsed-wave Doppler (LVOT-VTI) divided by the maximum velocity obtained by continuous-wave Doppler across the aortic valve (AV-VTI). In contrast to AVA measurement, the DI does not require the calculation of LVOT cross-sectional area, a major cause of erroneous assessment and underestimation of AVA. Hence, among patients with LG severe AS and preserved LV ejection fraction, calculation of DI in routine echocardiographic practice may be useful to identify a subgroup of patients at higher risk of mortality who may derive benefit from aortic valve replacement. This article aims to elucidate the Zva and DI in different clinical situations, correlate with the standard indexes of AS severity, LV geometry, and function, and thus prove to improve risk stratification and clinical decision making in patients with severe AS.

Arterial Hypertension in Aortic Valve Stenosis: A Critical Update

Aortic stenosis (AS) is a very common valve disease and is associated with high mortality once it becomes symptomatic. Arterial hypertension (HT) has a high prevalence among patients with AS leading to worse left ventricle remodeling and faster degeneration of the valve. HT also interferes with the assessment of the severity of AS, leading to an underestimation of the real degree of stenosis. Treatment of HT in AS has not historically been pursued due to the fear of excess reduction in afterload without a possibility of increasing stroke volume due to the fixed aortic valve, but most recent evidence shows that several drugs are safe and effective in reducing BP in patients with HT and AS. RAAS inhibitors and beta-blockers provide benefit in selected populations based on their profile of pharmacokinetics and pharmacodynamics. Different drugs, on the other hand, have proved to be unsafe, such as calcium channel blockers, or simply not easy enough to handle to be recommended in clinical practice, such as PDE5i, MRA or sodium nitroprusside. The present review highlights all available studies on HT and AS to guide antihypertensive treatment.

Ageing, Hypertension and Aortic Valve Stenosis: A Conscious Uncoupling

Aortic valve stenosis (AS) is no longer considered to be a disease of fixed left ventricular (LV) afterload (due to an obstructive valve), but rather, functions as a series circuit with important contributions from both the valve and ageing vasculature. Patients with AS are frequently elderly, with hypertension and a markedly remodelled aorta. The arterial component is sizable, and yet, the contribution of ventricular afterload has been difficult to determine. Arterial stiffening increases the speed of propagation of the blood pressure wave along the central arteries (estimated as the pulse wave velocity), which results in an earlier return of reflected waves. The effect is to augment blood pressure in the proximal aorta during systole, increasing the central pulse pressure and, in turn, placing even greater afterload on the heart. Elevated global LV afterload is known to have adverse consequences on LV remodelling, function and survival in patients with AS. Consequently, there is renewed focus on methods to estimate the relative contributions of local versus global changes in arterial mechanics and valvular haemodynamics in patients with AS. We present a review on existing and upcoming methods to quantify valvulo-arterial impedance and thereby global LV load in patients with AS.

Imaging-Guided Transcatheter Aortic Valve Replacement and Percutaneous Coronary Intervention in Decompensated Severe Aortic Stenosis with Acute Renal Impairment

An 82-year-old woman with severe aortic valve stenosis (AS) and a significant proximal right coronary artery (RCA) stenosis presented with decompensated heart failure and acute kidney injury. She was treated with intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) and trans-oesophageal echocardiography (TOE)-guided transcatheter aortic valve replacement (TAVR).

Structure and Rheological Properties of Bovine Aortic Heart Valve and Pericardium Tissue: Implications in Bioprosthetic and Tissue-Engineered Heart Valves

Heart valve (HV) diseases are among the leading causes of cardiac failure and deaths. Of the various HV diseases, damaged HV leaflets are among the primary culprits. In many cases, impaired HV restoration is not always possible, and the replacement of valves becomes necessary. Bioprosthetic HVs have been used for the replacement of the diseased valves, which is obtained from the sources of bovine and porcine origin, while tissue-engineered heart valves (TEHV) have emerged as a promising future solution. The bioprosthetic valves are prone to become calcified, and thus they last for only ten to fifteen years. The adequate understanding of the correlations between the biomechanics and rheological properties of native HV tissues can enable us to improve the durability of the bioprosthetic HV as well as help in the development of tissue-engineered heart valves (TEHV). In this study, the structural and rheological properties of native bovine aortic HV and pericardium tissues were investigated. The microstructures of the tissues were investigated using scanning electron microscopy, while the rheological properties were studied using oscillatory shear measurement and creep test. The reported results provide significant insights into the correlations between the microstructure and viscoelastic properties of the bovine aortic HV and pericardium tissues.

State-of-the-art Structural Interventions in Heart Failure

Heart failure (HF) is a leading cause of hospitalisation and healthcare costs worldwide. Acute decompensated heart failure accounts for more than 1 million hospitalisations in the US. Despite advances in the quality of acute and chronic HF disease management, gaps in knowledge about effective interventions to support the transition of care for patients with HF remain. Despite multiple trials of promising therapies, standard care consists of decongestion with IV diuretics and haemodynamic support with vasodilators and inotropes and this has remained largely unchanged during the past 45 years. Newer advances in medical innovations and structural heart disease interventions have now given promise to improved survival, outcomes and quality of life for patients with advanced HF of multiple aetiologies. In this article, we focus on structural interventions in the treatment of patients with HF.

Practical guidance for the implementation of stress echocardiography

Exercise stress testing has been widely undertaken for the diagnosis of heart diseases. The accurate assessment of clinical conditions can be conducted by comparing the findings obtained from the results of stress echocardiography with the changes in the blood/heart rate and electrocardiograms. Numerous overseas studies have reported the utility of stress echocardiography in diagnosing myocardial ischemia; in Japan, the use of this modality for this purpose was included in the national health insurance reimbursable list in 2012. Nevertheless, stress echocardiography is far from being a widespread practice in Japan. This might be due to insufficient equipment (e.g., ergometers, space for test implementation) at each medical institution, shortage of technicians and sonographers who are well experienced and who are responsible for obtaining images during stress testing. The other possible reasons include the limited evidence available in Japan and the lack of a standardized testing protocol. Further dissemination of the practice of exercise stress echocardiography in this country is deemed necessary to establish satisfactory evidence for the use of stress echocardiography in the Japanese population. To this end, efforts are underway to develop a standardized protocol and report format to be adopted throughout Japan. We here present a guideline created by the Guideline Development Committee of the Japanese Society of Echocardiography that describes safe and effective stress echocardiography protocols and report formats. The readers are encouraged to perform exercise stress echocardiography using the proposed template for consensus document and report attached to this guideline.

North American trial results at 1 year with the Sorin Freedom SOLO pericardial aortic valve

OBJECTIVES

A North American prospective, 15-centre Food and Drug Administration (FDA) valve trial was designed to assess the safety and effectiveness of the Freedom SOLO stentless pericardial aortic valve in the treatment of surgical aortic valve disease.

METHODS

Beginning in 2010, 251 patients (mean: 74.7 ± 7.5 years), were recruited in the Freedom SOLO aortic valve trial. One hundred eighty-nine patients have been followed for at least 1 year and are the basis for this review. Preoperatively, 54% of patients had NYHA functional class III or IV symptoms, and the majority of patients had a normal ejection fraction (EF) (median EF = 61%). Concomitant procedures were performed in 61.9% of patients, with coronary artery bypass grafting (CABG) (48.7%) being the most common followed by a MAZE procedure (13.7%). Reoperations were performed in 8.5% of patients in the study.

RESULTS

The entire cohort of 251 patients enrolled had 7 deaths prior to 30 days, 2 of which were valve-related (aspiration pneumonia and sudden death) and 5 were not valve-related. There were 11 deaths after 30 days, 1 valve-related (unknown cardiac death) and 10 not valve-related. Five valves were explanted, 3 early (endocarditis, acute insufficiency and possible root dissection) and 2 late (endocarditis). Thirty-day adverse events include arrhythmias requiring permanent pacemaker (4.2%), thromboembolic events (3.7%) and thrombocytopenia (7.4%). One-year follow-up of all 189 patients demonstrated mean gradients for valve sizes 19, 21, 23, 25 and 27 mm of 11.7, 7.8, 6.3, 4.6 and 5.0 mmHg, respectively. Effective orifice areas for the same valve sizes were 1.2, 1.3, 1.6, 1.8 and 1.9 cm(2), respectively. Ninety-six percent of patients (181/189) were in NYHA class I or II at the 1-year follow-up.

CONCLUSIONS

The Freedom SOLO stentless pericardial aortic valve demonstrated excellent haemodynamics and a good safety profile out to the 1 year of follow-up.

Calcific Aortic Valve Disease: Molecular Mechanisms and Therapeutic Approaches

Calcification occurs in atherosclerotic vascular lesions and In the aortic valve. Calcific aortic valve disease (CAVD) is a slow, progressive disorder that ranges from mild valve thickening without obstruction of blood flow, termed aortic sclerosis, to severe calcification with impaired leaflet motion, termed aortic stenosis. In the past, this process was thought to be 'degenerative' because of time-dependent wear and tear of the leaflets, with passive calcium deposition. The presence of osteoblasts in atherosclerotic vascular lesions and in CAVD implies that calcification is an active, regulated process akin to atherosclerosis, with lipoprotein deposition and chronic inflammation. If calcification is active, via pro-osteogenic pathways, one might expect that development and progression of calcification could be inhibited. The overlap in the clinical factors associated with calcific valve disease and atherosclerosis provides further support for a shared disease mechanism. In our recent research we used an in vitro porcine valve interstitial cell model to study spontaneous calcification and potential promoters and inhibitors. Using this model, we found that denosumab, a human monoclonal antibody targeting the receptor activator of nuclear factor-κB ligand may, at a working concentration of 50 μg/mL, inhibit induced calcium deposition to basal levels.

Depressed Systemic Arterial Compliance is Associated with the Severity of Heart Failure Symptoms in Moderate-to-Severe Aortic Stenosis: a Cross-Sectional Retrospective Study

BACKGROUND

Patients with aortic stenosis (AS) may develop heart failure even in the absence of severe valve stenosis. Our aim was to assess the contribution of systemic arterial properties and the global left ventricular afterload to graded heart failure symptoms in AS.

METHODS

We retrospectively reviewed medical records of 157 consecutive subjects (mean age, 71±10 years; 79 women and 78 men) hospitalized owing to moderate-to-severe degenerative AS. Exclusion criteria included more than mild aortic insufficiency or disease of another valve, atrial fibrillation, coronary artery disease, severe respiratory disease or anemia. Heart failure symptoms were graded by NYHA class at admission. Systemic arterial compliance (SAC) and valvulo-arterial impedance (Zva) were derived from routine echocardiography and blood pressure.

RESULTS

Sixty-one patients were asymptomatic, 49 presented mild (NYHA II) and 47 moderate-to-severe (NYHA III-IV) heart failure symptoms. Mild symptoms were associated with lower SAC and transvalvular gradients, while more severe exercise intolerance coincided with older age, lower systolic blood pressure, smaller aortic valve area and depressed ejection fraction. By multiple ordinal logistic regression, the severity of heart failure symptoms was related to older age, depressed ejection fraction and lower SAC. Each decrease in SAC by 0.1 ml/m² per mmHg was associated with an increased adjusted odds ratio (OR) of a patient being in one higher category of heart failure symptoms graded as no symptoms, mild exercise intolerance and advanced exercise intolerance (OR: 1.16 [95% CI, 1.01-1.35], P=0.045).

CONCLUSIONS

Depressed SAC may enhance exercise intolerance irrespective of stenosis severity or left ventricular systolic function in moderate-to-severe AS. This finding supports the importance of non-valvular factors for symptomatic status in AS.

Current status of stress echocardiography: is it a required procedure for every sonographer?

BACKGROUND

Stress echocardiography is a versatile modality in the clinical cardiology. In its earlier days, its sole indication was restricted to diagnosing coronary artery disease. However, in response to the rapid development of ultrasound technology and analysis software, the indications have now evolved with expansion to several fields of cardiovascular disease.

METHODS

I reviewed previous stress echocardiography publications, and discussed the current status of stress echocardiography in routine clinical setting.

RESULTS

Although its portability and online assessment make possible for immediate diagnosis even at the bedside, establishment of an appropriate procedure and an accurate assessment require some experience. Other imaging competitors, such as multidetector computed tomography and cardiac magnetic resonance are gradually replacing the role of stress echocardiography in some fields. However, stress echocardiography has a potential for other new fields, including valvular heart disease and congestive heart failure.

CONCLUSION

Although primary indication of stress echocardiography for coronary artery disease seems to be not relevant especially in Japan, novel indication of stress echocardiography in other field of cardiovascular disease is rapidly expanding in conjunction with the advent of new technology. Stress echocardiography is not a tool for limited researchers, but rather a fundamental routine method of choice for every sonographer.

Aortic root geometry in patients with aortic stenosis assessed by real-time three-dimensional transesophageal echocardiography

BACKGROUND

The authors hypothesized that aortic root geometry is different between bicuspid and tricuspid aortic stenosis (AS) that can be assessed using real-time three-dimensional (3D) transesophageal echocardiography. The aims of this study were (1) to validate the accuracy of 3D transesophageal echocardiographic measurements of the aortic root against multidetector computed tomography as a reference, (2) to determine the difference of aortic root geometry between patients with tricuspid and bicuspid AS, and (3) to assess its impact on pressure recovery.

METHODS

In protocol 1, 3D transesophageal echocardiography and contrast-enhanced multidetector computed tomography were performed in 40 patients. Multiplanar reconstruction was used to measure the aortic annulus, the sinus of Valsalva, and the sinotubular junction area, as well as the distance and volume from the aortic annulus to the sinotubular junction. In protocol 2, the same 3D transesophageal echocardiographic measurements were performed in patients with tricuspid AS (n = 57) and bicuspid AS (n = 26) and in patients without AS (n = 32). The energy loss coefficient was also measured in patients with AS.

RESULTS

In protocol 1, excellent correlations of aortic root geometric parameters were noted between the two modalities. In protocol 2, compared with patients without AS, those with tricuspid AS had smaller both sinotubular junction areas and longitudinal distances, resulting in a 23% reduction of aortic root volume. In contrast, patients with bicuspid AS had larger transverse areas and longitudinal distances, resulting in a 30% increase in aortic root volume. The energy loss coefficient revealed more frequent reclassification from severe AS to moderate AS in patients with tricuspid AS (17%) compared with those with bicuspid AS (10%).

CONCLUSIONS

Three-dimensional transesophageal echocardiography successfully revealed different aortic root morphologies between tricuspid and bicuspid AS, which have different impacts on pressure recovery.

Aortic stenosis in the elderly: challenges in diagnosis and therapy

Severe aortic valve stenosis, remains the main cause of morbidity and mortality in the elderly, reaching a prevalence of 2-7% above the age of 65 years old. Despite its frequency and the development in invasive and noninvasive approach of the disease, several of its aspects remain controversial. This review is focused on the clinical aspects, the indices for assessment severity, newly markers related to prognosis and new therapeutic modalities for the elderly population. The term low flow, low gradient severe aortic stenosis with preserved LV systolic function has revealed a new modality in the field of diagnostic evaluation and therapeutic approach. Aortic valve replacement is the choice therapy for symptomatic severe aortic stenosis. Despite the recent advances in cardiac surgery, the overall operative mortality rate for isolated aortic valve replacement surgery ranges from 2.5% to 4.0% and is higher in octogenarians and can be up to 25% in patients with comorbid conditions. The fact that surgery is not being performed for 30% or more of patients requiring it, a great attention was attracted to the percutaneous transcatheter implantation of a stent-mounted aortic valve. The up to now experience of transcatheter valve implantation in more than 25,000 patients, has shown promising results in terms of mortality and quality of life. Echocardiography still plays the central role for the evaluation of the elderly patient, as it can illustrate the pathophysiological alterations during the course of aortic valve stenosis, and guide appropriate therapy.

Aortic stenosis

In developed countries, aortic stenosis is the most prevalent of all valvular heart diseases. A manifestation of ageing, the disorder is becoming more frequent as the average age of the population increases. Symptomatic severe disease is universally fatal if left untreated yet is consistent with a typical lifespan when mechanical relief of the stenosis is provided in a timely fashion. Management of mild disease, severe asymptomatic disease, and far advanced disease, and the effect of new percutaneous treatments, provide both controversy and exciting promise to care of patients with aortic stenosis. We discuss these issues in this Review.