Validation of Conventional and Simplified Methods to Calculate Projected Valve Area at Normal Flow Rate in Patients With Low Flow, Low Gradient Aortic Stenosis: The Multicenter TOPAS (True or Pseudo Severe Aortic Stenosis) Study

Dilemma in the therapeutic management of low-gradient aortic stenosis

PURPOSE OF REVIEW

Grading of aortic stenosis is essential in aortic stenosis management patients. However, despite clear thresholds provided in the guidelines, up to 30% of patients have discordant grading of aortic stenosis. The management of patients with low gradients/velocity despite tight aortic valve area is challenging.

RECENT FINDINGS

Recent studies demonstrated that patients with or without low flow may have a severe aortic stenosis despite a low gradient. Moreover, aortic valve replacement has been shown to improve outcome in low-gradient aortic stenosis patients with or without low flow. Finally, measurement of aortic valve calcification by multidetector computed tomography is an important tool to assess aortic stenosis severity in these patients.

SUMMARY

The presence of a low gradient/velocity despite a tight aortic valve area could be linked to low ejection fraction or low flow with preserved ejection fraction but also with normal flow and normal ejection fraction. In each situation, aortic stenosis could be truly severe or pseudosevere, and the severity of aortic stenosis has to be accurately evaluated for clinical decision-making. Nowadays, two types of interventions are available: surgical and transcatheter aortic valve replacement, whereas conservative management should be considered as a palliative treatment in patients with proven severe aortic stenosis and symptoms or left ventricle dysfunction.

An Alternative Method to Calculate Simplified Projected Aortic Valve Area at Normal Flow Rate

Background

Simplified projected aortic valve area (EOA_proj) is a valuable echocardiographic parameter in the evaluation of low flow low gradient aortic stenosis (LFLG AS). Its widespread use in clinical practice is hampered by the laborious process of flow rate (Q) calculation.

Objetive

This study proposes a less burdensome, alternative method of Q calculation to be incorporated in the original formula of EOA_proj and measures the agreement between the new proposed method of EOA_proj calculation and the original one.

Methods

Retrospective observational single-institution study that included all consecutive patients with classic LFLG AS that showed a Q variation with dobutamine infusion ≥ |15|% by both calculation methods.

Results

Twenty-two consecutive patients with classical LFLG AS who underwent dobutamine stress echocardiography were included. Nine patients showed a Q variation with dobutamine infusion calculated by both classical and alternative methods ≥ |15|% and were selected for further statistical analysis. Using the Bland-Altman method to assess agreement we found a systematic bias of 0,037 cm² (95% CI 0,004 - 0,066), meaning that on average the new method overestimates the EOA_proj in 0,037 cm² compared to the original method. The 95% limits of agreement are narrow (from -0,04 cm² to 0,12 cm²), meaning that for 95% of individuals, EOA_proj calculated by the new method would be between 0,04 cm² less to 0,12 cm² more than the EOA_proj calculated by the original equation.

Conclusion

The bias and 95% limits of agreement of the new method are narrow and not clinically relevant, supporting the potential interchangeability of the two methods of EOA_proj calculation. As the new method requires less additional measurements, it would be easier to implement in clinical practice, promoting an increase in the use of EOA_proj.

The mystery of defining aortic valve area: what have we learnt from three-dimensional imaging modalities?

Aortic valve area is one of the main criteria used by echocardiography to determine the degree of valvular aortic stenosis, and it is calculated using the continuity equation which assumes that the flow volume of blood is equal at two points, the aortic valve area and the left ventricular outflow tract (LVOT). The main fallacy of this equation is the assumption that the LVOT area which is used to calculate the flow volume at the LVOT level is circular, where it is often an ellipse and sometimes irregular. The aim of this review is to explain the physiology of the continuity equation, the different sources of errors, the added benefits of using three-dimensional imaging modalities to measure LVOT area, the latest recommendations related to valvular aortic stenosis, and to introduce future perspectives. A literature review of studies comparing aortic valve area and LVOT area, after using three-dimensional data, has shown underestimation of both measurements when using the continuity equation. This has more impact on patients with discordant echocardiographic measurements when aortic valve area is disproportionate to haemodynamic measurements in assessing the degree of aortic stenosis. Although fusion imaging modalities of LVOT area can help in certain group of patients to address the issue of aortic valve area underestimation, further research on introducing a correction factor to the conventional continuity equation might be more rewarding, saving patients additional tests and potential radiation, with no clear evidence of cost-effectiveness.

Recommendations on the echocardiographic assessment of aortic valve stenosis: a focused update from the European Association of Cardiovascular Imaging and the American Society of Echocardiography

Echocardiography is the key tool for the diagnosis and evaluation of aortic stenosis. Because clinical decision-making is based on the echocardiographic assessment of its severity, it is essential that standards are adopted to maintain accuracy and consistency across echocardiographic laboratories. Detailed recommendations for the echocardiographic assessment of valve stenosis were published by the European Association of Echocardiography and the American Society of Echocardiography in 2009. In the meantime, numerous new studies on aortic stenosis have been published with particular new insights into the difficult subgroup of low gradient aortic stenosis making an update of recommendations necessary. The document focuses in particular on the optimization of left ventricular outflow tract assessment, low flow, low gradient aortic stenosis with preserved ejection fraction, a new classification of aortic stenosis by gradient, flow and ejection fraction, and a grading algorithm for an integrated and stepwise approach of artic stenosis assessment in clinical practice.

Mechanical Intervention for Aortic Valve Stenosis in Patients With Heart Failure and Reduced Ejection Fraction

The risk and benefit of mechanical interventions in valvular heart disease have been primarily described among patients with normal ejection fraction. The advent of nonsurgical mechanical interventions for aortic stenosis (transcatheter aortic valve replacement) may alter the risk-benefit ratio for patients who would otherwise be at increased risk for valve surgery. This review describes the epidemiology and pathophysiology of aortic stenosis with heart failure and reduced ejection fraction and summarizes the current registry and clinical trial data applicable to this frequently encountered high-risk group. It concludes with discussion of ongoing trials, new approaches, emerging indications, and a potential clinical algorithm incorporating optimal mechanical intervention for patients with aortic stenosis and concomitant reduced ejection fraction.

Aortic Stenosis, a Left Ventricular Disease: Insights from Advanced Imaging

Aortic stenosis (AS) is the most common primary valve disorder in the elderly with an increasing prevalence. It is increasingly clear that it is also a disease of the left ventricle (LV) rather than purely the aortic valve. The transition from left ventricular hypertrophy to fibrosis results in the eventual adverse effects on systolic and diastolic function. Appropriate selection of patients for aortic valve intervention is crucial, and current guidelines recommend aortic valve replacement in severe AS with symptoms or in asymptomatic patients with left ventricular ejection fraction (LVEF) <50 %. LVEF is not a sensitive marker and there are other parameters used in multimodality imaging techniques, including longitudinal strain, exercise stress echo and cardiac MRI that may assist in detecting subclinical and subtle LV dysfunction. These findings offer potentially better ways to evaluate patients, time surgery, predict recovery and potentially offer targets for specific therapies. This article outlines the pathophysiology behind the LV response to aortic stenosis and the role of advanced multimodality imaging in describing it.

The Role of Stress Echocardiography in Valvular Heart Disease: A Current Appraisal

Stress echocardiography is a widely available, safe, low-cost, versatile imaging modality which is becoming increasingly recognized as a valuable tool in the assessment of patients with native and prosthetic left-sided valvular heart disease. It provides a quantitative assessment to help guide clinical decision-making when discordance exists between symptoms and severity of valve disease. Exercise (treadmill or bicycle) remains the preferred stress modality, but pharmacological augmentation with dobutamine can be used if needed. Low-dose dobutamine stress echocardiography is specifically valuable in patients with low-flow, low-gradient aortic stenosis when attempting to differentiate true severe aortic stenosis from pseudo-severe aortic stenosis. Stress echocardiography not only identifies high-risk features that indicate need for earlier surgery, it also provides useful information for the peri- and postoperative period, including long-term outcome, risk stratification to guide monitoring frequency, and offers guidance for eligibility in competitive sports participation. As research continues to expand the utility of stress echocardiography in the management of patients with valvular heart disease, future research should focus on the recognition of newer parameters identifying high-risk features including subsequent validation in a large population.

Multimodality Imaging for Planning and Follow-up of Transcatheter Aortic Valve Replacement

The complementary modalities of Doppler echocardiography and multidetector computed tomography are most frequently used for the planning and follow-up of transcatheter aortic valve replacement (TAVR). TAVR is now a well-established modality in the treatment of high-risk and inoperable patients with symptomatic severe aortic stenosis. Furthermore, recent studies have shown that TAVR is equivalent or superior to surgical aortic valve replacement in patients at intermediate surgical risk. We review the most commonly used imaging modalities and discuss their respective strengths and contributions to optimal patient selection, procedure planning, implementation, and follow-up in TAVR.

Evolving new concepts in the assessment of aortic stenosis

Echocardiography has been pivotal in evaluating aortic stenosis (AS) over the past several decades. Recent experience has shown a wide spectrum in the clinical presentation of AS. A better understanding of the underlying hemodynamic principles has resulted in emergence of new subtypes of AS. New treatment modalities have also been introduced, requiring precise evaluation of aortic valve (AV) pathology for implementation of these therapies. This review will discuss new concepts and indices in the use of echocardiography in patients with AS. Specifically, we will address the hemodynamic characteristics, clinical presentation, and management of normal-flow, high-gradient; paradoxical low-flow, low-gradient; and classical low-flow, low-gradient aortic stenoses.

Cardiac amyloidosis mimicking severe aortic valve stenosis - a case report demonstrating diagnostic pitfalls and role of dobutamine stress echocardiography

Background

Aortic valve stenosis is a common finding diagnosed with high sensitivity in transthoracic echocardiography, but the examiner often finds himself confronted with uncertain results in patients with moderate pressure gradients and concomitant systolic heart failure. While patients with true-severe low-gradient aortic valve stenosis with either reduced or preserved left ventricular systolic function are primarily candidates for valve replacement, there is a relevant proportion of patients with pseudo-severe aortic valve stenosis anticipated not to benefit but actually rather deteriorate by interventional therapy or surgery.

Case presentation

In this article we present a case report of a male patient with pseudo-severe aortic valve stenosis due to cardiac amyloidosis highlighting the diagnostic schedule. The patient underwent stress echocardiography because of discrepant findings in transthoracic echocardiography and cardiac catheterization regarding the severity of aortic valve stenosis. After evaluation of the results, it became clear that he had a need for optimum heart failure medication and implantation of a cardiac resynchronization therapy defibrillator.

Conclusion

Due to the pitfalls in conventional as well as invasive diagnostics at rest, Stress echocardiography should be considered part of the standard optimum diagnostic spectrum in all unclear or borderline cases in order to confirm the correct diagnosis and constitute optimal therapy.

Integrated strategy for in vitro characterization of a bileaflet mechanical aortic valve

Background

Haemodynamic performance of heart valve prosthesis can be defined as its ability to fully open and completely close during the cardiac cycle, neither overloading heart work nor damaging blood particles when passing through the valve. In this perspective, global and local flow parameters, valve dynamics and blood damage safety of the prosthesis, as well as their mutual interactions, have all to be accounted for when assessing the device functionality. Even though all these issues have been and continue to be widely investigated, they are not usually studied through an integrated approach yet, i.e. by analyzing them simultaneously and highlighting their connections.

Results

An in vitro test campaign of flow through a bileaflet mechanical heart valve (Sorin Slimline 25 mm) was performed in a suitably arranged pulsatile mock loop able to reproduce human systemic pressure and flow curves. The valve was placed in an elastic, transparent, and anatomically accurate model of healthy aorta, and tested under several pulsatile flow conditions. Global and local hydrodynamics measurements and leaflet dynamics were analysed focusing on correlations between flow characteristics and valve motion. The haemolysis index due to the valve was estimated according to a literature power law model and related to hydrodynamic conditions, and a correlation between the spatial distribution of experimental shear stress and pannus/thrombotic deposits on mechanical valves was suggested. As main and general result, this study validates the potential of the integrated strategy for performance assessment of any prosthetic valve thanks to its capability of highlighting the complex interaction between the different physical mechanisms that govern transvalvular haemodynamics.

Conclusions

We have defined an in vitro procedure for a comprehensive analysis of aortic valve prosthesis performance; the rationale for this study was the belief that a proper and overall characterization of the device should be based on the simultaneous measurement of all different quantities of interest for haemodynamic performance and the analysis of their mutual interactions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12938-017-0314-2) contains supplementary material, which is available to authorized users.

Rationale and design of the Transcatheter Aortic Valve Replacement to UNload the Left ventricle in patients with ADvanced heart failure (TAVR UNLOAD) trial

BACKGROUND

Coexistence of moderate aortic stenosis (AS) in patients with heart failure (HF) with reduced ejection fraction is not uncommon. Moderate AS increases afterload, whereas pharmacologic reduction of afterload is a pillar of contemporary HF management.

HYPOTHESIS

Unloading the left ventricle by reducing the transaortic gradient with transfemoral transcatheter aortic valve replacement (TAVR) may improve clinical outcomes in patients with moderate AS and HF with reduced ejection fraction.

STUDY DESIGN

The TAVR UNLOAD (NCT02661451) is an international, multicenter, randomized, open-label, clinical trial comparing the efficacy and safety of TAVR with the Edwards SAPIEN 3 Transcatheter Heart Valve in addition to optimal heart failure therapy (OHFT) vs OHFT alone in patients with moderate AS (defined by a mean transaortic gradient ≥20 mm Hg and <40 mm Hg, and an aortic valve area >1.0 cm² and ≤1.5 cm² at rest or after dobutamine stress echocardiography) and reduced ejection fraction. A total of 600 patients will be randomized in a 1:1 fashion. Clinical follow-up is scheduled at 1, 6, and 12 months, and 2 years after randomization. The primary end point is the hierarchical occurrence of all-cause death, disabling stroke, hospitalizations related to HF, symptomatic aortic valve disease or nondisabling stroke, and the change in the Kansas City Cardiomyopathy Questionnaire at 1 year. Secondary end points capture effects on clinical outcome, biomarkers, echocardiographic parameters, and quality of life.

SUMMARY

The TAVR UNLOAD trial aims to test the hypothesis that TAVR on top of OHFT improves clinical outcomes in patients with moderate AS and HF with reduced ejection fraction.

Relationship Between QT Interval and Outcome in Low-Flow Low-Gradient Aortic Stenosis With Low Left Ventricular Ejection Fraction

BACKGROUND

QT interval has been shown to be associated with cardiovascular events. There is no data regarding the association between QT interval and left ventricular (LV) function and prognosis in patients with low LV ejection fraction (LVEF), low-flow, low-gradient aortic stenosis (LF-LG AS). We aimed to examine the relationship between corrected QT interval (QT_c) and LV function and outcome in these patients.

METHODS AND RESULTS

Ninety-three patients (73±10 years; 74% men) with LF-LG AS (mean gradient <40 mm Hg and indexed aortic valve area ≤0.6 cm²/m²) and reduced LVEF (≤40%) were prospectively included in this analysis and 63 of them underwent aortic valve replacement within 3 months following inclusion. Prolonged QT_c was defined as QT_c >450 ms in men and >470 ms in women. LV global longitudinal strain was measured by speckle tracking and expressed in absolute value |%|. QT_c correlated with the following: global longitudinal strain (r=-0.40, P=0.005), LVEF (r=-0.27, P=0.02), stroke volume (r=-0.35, P=0.007), and B-type natriuretic peptide (r=0.45, P=0.0006). During a median follow-up of 2.0 years, 49 patients died. Prolonged QT_c was associated with a 2-fold increase in all-cause mortality (hazard ratio=2.05; P=0.01) and cardiovascular mortality (hazard ratio=1.89; P=0.04). In multivariable analysis adjusted for EuroSCORE, aortic valve replacement, previous myocardial infarction, LVEF, and ß-blocker medication, prolonged QT_c was independently associated with all-cause mortality (hazard ratio=2.56; P=0.008) and cardiovascular mortality (hazard ratio=2.50; P=0.02).

CONCLUSIONS

In patients with LF-LG AS and reduced LVEF, longer QT_c interval was associated with worse LV function and increased risk of death. Assessment of QT_c may provide a simple and inexpensive tool to enhance risk stratification in LF-LG AS patients.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT 01835028.

Low-gradient aortic stenosis

An important proportion of patients with aortic stenosis (AS) have a 'low-gradient' AS, i.e. a small aortic valve area (AVA <1.0 cm(2)) consistent with severe AS but a low mean transvalvular gradient (<40 mmHg) consistent with non-severe AS. The management of this subset of patients is particularly challenging because the AVA-gradient discrepancy raises uncertainty about the actual stenosis severity and thus about the indication for aortic valve replacement (AVR) if the patient has symptoms and/or left ventricular (LV) systolic dysfunction. The most frequent cause of low-gradient (LG) AS is the presence of a low LV outflow state, which may occur with reduced left ventricular ejection fraction (LVEF), i.e. classical low-flow, low-gradient (LF-LG), or preserved LVEF, i.e. paradoxical LF-LG. Furthermore, a substantial proportion of patients with AS may have a normal-flow, low-gradient (NF-LG) AS: i.e. a small AVA-low-gradient combination but with a normal flow. One of the most important clinical challenges in these three categories of patients with LG AS (classical LF-LG, paradoxical LF-LG, and NF-LG) is to differentiate a true-severe AS that generally benefits from AVR vs. a pseudo-severe AS that should be managed conservatively. A low-dose dobutamine stress echocardiography may be used for this purpose in patients with classical LF-LG AS, whereas aortic valve calcium scoring by multi-detector computed tomography is the preferred modality in those with paradoxical LF-LG or NF-LG AS. Although patients with LF-LG severe AS have worse outcomes than those with high-gradient AS following AVR, they nonetheless display an important survival benefit with this intervention. Some studies suggest that transcatheter AVR may be superior to surgical AVR in patients with LF-LG AS.

Multimodality imaging for the diagnosis and assessment of aortic stenosis severity

INTRODUCTION

Aortic stenosis (AS) is the most common cause of valvular heart disease. Imaging plays a major role in the diagnosis and evaluation of AS severity.

AREAS COVERED

The present review focuses on new emerging concepts in AS by stressing the substantial value of imaging into the understanding of the complex pathophysiology and management of AS. Expert commentary: Though, standard 2D echocardiography is often diagnostic multi-modality imaging can be required in patients with doubtful results or to refine the evaluation of AS.

Pathophysiology and management of multivalvular disease

Multivalvular disease (MVD) is common among patients with valvular disease, and has a complex pathophysiology dependent on the specific combination of valve lesions. Diagnosis is challenging because several echocardiographic methods commonly used for the assessment of stenosis or regurgitation have been validated only in patients with single-valve disease. Decisions about the timing and type of treatment should be made by a multidisciplinary heart valve team, on a case-by-case basis. Several factors should be considered, including the severity and consequences of the MVD, the patient's life expectancy and comorbidities, the surgical risk associated with combined valve procedures, the long-term risk of morbidity and mortality associated with multiple valve prostheses, and the likelihood and risk of reoperation. The introduction of transcatheter valve therapies into clinical practice has provided new treatment options for patients with MVD, and decision-making algorithms on how to combine surgical and percutaneous treatment options are evolving rapidly. In this Review, we discuss the pathophysiology, diagnosis, and treatment of MVD, focusing on the combinations of valve pathologies that are most often encountered in clinical practice.

Calcific aortic stenosis

Calcific aortic stenosis (AS) is the most prevalent heart valve disorder in developed countries. It is characterized by progressive fibro-calcific remodelling and thickening of the aortic valve leaflets that, over years, evolve to cause severe obstruction to cardiac outflow. In developed countries, AS is the third-most frequent cardiovascular disease after coronary artery disease and systemic arterial hypertension, with a prevalence of 0.4% in the general population and 1.7% in the population >65 years old. Congenital abnormality (bicuspid valve) and older age are powerful risk factors for calcific AS. Metabolic syndrome and an elevated plasma level of lipoprotein(a) have also been associated with increased risk of calcific AS. The pathobiology of calcific AS is complex and involves genetic factors, lipoprotein deposition and oxidation, chronic inflammation, osteoblastic transition of cardiac valve interstitial cells and active leaflet calcification. Although no pharmacotherapy has proved to be effective in reducing the progression of AS, promising therapeutic targets include lipoprotein(a), the renin-angiotensin system, receptor activator of NF-κB ligand (RANKL; also known as TNFSF11) and ectonucleotidases. Currently, aortic valve replacement (AVR) remains the only effective treatment for severe AS. The diagnosis and staging of AS are based on the assessment of stenosis severity and left ventricular systolic function by Doppler echocardiography, and the presence of symptoms. The introduction of transcatheter AVR in the past decade has been a transformative therapeutic innovation for patients at high or prohibitive risk for surgical valve replacement, and this new technology might extend to lower-risk patients in the near future.

Evaluation of aortic stenosis: an update--including low-flow States, myocardial mechanics, and stress testing

Degenerative aortic stenosis (AS) is one of the most frequent valvular heart diseases in Western countries. Echocardiography plays a central role in the evaluation and management of patients with AS. To overcome the inherent inconsistencies between the echocardiographic parameters defining severe AS and to unify concepts, a new classification based on the interplay between flow and gradients has recently been adopted. Outcome studies of asymptomatic patients with preserved left ventricular ejection fraction (LVEF), as classified by this new approach, have shown that low-flow (LF) states are associated with poor outcome, that the classical normal-flow/high-gradient pattern has an intermediate outcome, while normal-flow/low-gradient severe AS seems to have an outcome comparable to moderate AS and such patients do not benefit from aortic valve replacement. Patients with LF/low-gradient severe AS with preserved LVEF, also known as "paradoxical LF/low-gradient AS," have the worst outcome and benefit greatly from surgical or percutaneous valve replacement, provided that severity is proven. In patients with LF/low-gradient and depressed LVEF, dobutamine stress echocardiography has an important role to distinguish severe from pseudo-severe AS and to assess surgical risk. Assessment of aortic valve calcium score, as well as computation of projected effective orifice aortic area at normal trans-valvular flow rates, has proved to be very useful to distinguish severe from pseudo-severe AS in LF/low-gradient AS with both reduced and preserved LVEF. Asymptomatic patients with normal flow/gradient should be submitted to an exercise test; exercise echocardiography can identify patients at increased risk when mean gradient increases by >18-20 mmHg and/or pulmonary arterial hypertension develops during exercise.

Tricuspid Regurgitation Is Associated With Increased Risk of Mortality in Patients With Low-Flow Low-Gradient Aortic Stenosis and Reduced Ejection Fraction: Results of the Multicenter TOPAS Study (True or Pseudo-Severe Aortic Stenosis)

OBJECTIVES

This study sought to examine the impact of tricuspid regurgitation (TR) on mortality in patients with low-flow, low-gradient (LF-LG) aortic stenosis (AS) and reduced left ventricular ejection fraction (LVEF).

BACKGROUND

TR is often observed in patients with LF-LG AS and low LVEF, but its impact on prognosis remains unknown.

METHODS

A total of 211 patients (73±10 years of age; 77% men) with LF-LG AS (mean gradient<40 mm Hg and indexed aortic valve area [AVA]≤0.6 cm2/m2) and reduced LVEF (≤40%) were prospectively enrolled in the TOPAS (True or Pseudo-Severe Aortic Stenosis) study and 125 (59%) of them underwent aortic valve replacement (AVR) within 3 months following inclusion. The severity of AS was assessed by the projected AVA (AVAproj) at normal flow rate (250 ml/s), as previously described and validated. The severity of TR was graded according to current guidelines.

RESULTS

Among the 211 patients included in the study, 22 (10%) had no TR, 113 (54%) had mild (grade 1), 50 (24%) mild-to-moderate (grade 2), and 26 (12%) moderate-to-severe (grade 3) or severe (grade 4) TR. During a mean follow-up of 2.4±2.2 years, 104 patients (49%) died. Univariable analysis showed that TR≥2 was associated with increased risk of all-cause mortality (hazard ratio [HR]: 1.82, 95% confidence interval [CI]: 1.22 to 2.71; p=0.004) and cardiovascular mortality (HR: 1.85, 95% CI: 1.20 to 2.83; p=0.005). After adjustment for age, sex, coronary artery disease, AVAproj, LVEF, stroke volume index, right ventricular dysfunction, mitral regurgitation, and type of treatment (AVR vs. conservative), the presence of TR≥2 was an independent predictor of all-cause mortality (HR: 1.88, 95% CI: 1.08 to 3.23; p=0.02) and cardiovascular mortality (HR: 1.92, 95% CI: 1.05 to 3.51; p=0.03). Furthermore, in patients undergoing AVR, TR≥3 was an independent predictor of 30-day mortality compared with TR=0/1 (odds ratio [OR]: 7.24, 95% CI: 1.56 to 38.2; p=0.01) and TR=2 (OR: 4.70, 95% CI: 1.00 to 25.90; p=0.05).

CONCLUSIONS

In patients with LF-LG AS and reduced LVEF, TR is independently associated with increased risk of cumulative all-cause mortality and cardiovascular mortality regardless of the type of treatment. In patients undergoing AVR, moderate/severe TR is associated with increased 30-day mortality. Further studies are needed to determine whether TR is a risk marker or a risk factor of mortality and whether concomitant surgical correction of TR at the time of AVR might improve outcomes for this high-risk population.

Low gradient aortic stenosis

OPINION STATEMENT

Severe low-gradient (LG) aortic stenosis (AS) [aortic valve area (AVA) ≤ 1.0 cm(2), mean pressure gradient (MG) < 40 mmHg] represents a frequently encountered and challenging clinical dilemma. A systematic approach, which often requires several imaging modalities, should be undertaken to confirm the hemodynamic findings and rule out measurement error. Low-flow conditions often account for the discrepancy and can be present whether the left ventricular ejection fraction (LVEF) is depressed or normal. In patients with classical low-flow (LF), LG AS in which LVEF is reduced (<40-50 %), dobutamine stress echocardiography (DSE) should be used to distinguish patients with true severe AS and pseudo-severe AS, as well as to evaluate for the presence of left ventricular contractile or flow reserve. Surgical or transcatheter aortic valve replacement (AVR) should likely be reserved for those patients with true severe AS. Patient outcome with medical or surgical management generally relates to patient functional capacity, stenosis severity, and left ventricular functional reserve. Patients with severe LG AS with preserved LVEF can have a stroke volume that is either normal (>35 mL/m(2)) or low (<35 mL/m(2)). New data suggest that DSE can identify pseudo-severe AS in up to 30 % of patients with severe LF-LG AS with preserved LVEF. AVR should likely be restricted to those patients with true severe AS, although there is currently little data to support this strategy. Symptomatic patients with severe LG AS with preserved LVEF, whether they have normal or low flow, should be offered AVR. Transcatheter AVR provides an alternative therapeutic option in the high-risk patient.

Echocardiographic Evaluation of Aortic Stenosis - Normal Flow and Low Flow Scenarios

The echocardiographic evaluation of the patient with aortic stenosis (AS) has evolved in recent years, beyond confirming the diagnosis and measuring the resting mean pressure gradient or valve area. New echocardiographic approaches have developed to address the clinical dilemmas related to discordant haemodynamic data, asymptomatic haemodynamically severe AS and low-flow, low-gradient AS in order to better evaluate the disease severity, enhance the risk stratification of patients and provide important prognostic information. This article reviews the echocardiographic evaluation of the AS patient and focuses on the echocardiographic assessment of the haemodynamic severity, the prediction of clinical outcome and the use of echocardiography to guide patient management in the presence of normal flow and low flow scenarios.

Impact of aortic valve calcification, as measured by MDCT, on survival in patients with aortic stenosis: results of an international registry study

BACKGROUND

Aortic valve calcification (AVC) load measures lesion severity in aortic stenosis (AS) and is useful for diagnostic purposes. Whether AVC predicts survival after diagnosis, independent of clinical and Doppler echocardiographic AS characteristics, has not been studied.

OBJECTIVES

This study evaluated the impact of AVC load, absolute and relative to aortic annulus size (AVCdensity), on overall mortality in patients with AS under conservative treatment and without regard to treatment.

METHODS

In 3 academic centers, we enrolled 794 patients (mean age, 73 ± 12 years; 274 women) diagnosed with AS by Doppler echocardiography who underwent multidetector computed tomography (MDCT) within the same episode of care. Absolute AVC load and AVCdensity (ratio of absolute AVC to cross-sectional area of aortic annulus) were measured, and severe AVC was separately defined in men and women.

RESULTS

During follow-up, there were 440 aortic valve implantations (AVIs) and 194 deaths (115 under medical treatment). Univariate analysis showed strong association of absolute AVC and AVCdensity with survival (both, p < 0.0001) with a spline curve analysis pattern of threshold and plateau of risk. After adjustment for age, sex, coronary artery disease, diabetes, symptoms, AS severity on hemodynamic assessment, and LV ejection fraction, severe absolute AVC (adjusted hazard ratio [HR]: 1.75; 95% confidence interval [CI]: 1.04 to 2.92; p = 0.03) or severe AVCdensity (adjusted HR: 2.44; 95% CI: 1.37 to 4.37; p = 0.002) independently predicted mortality under medical treatment, with additive model predictive value (all, p ≤ 0.04) and a net reclassification index of 12.5% (p = 0.04). Severe absolute AVC (adjusted HR: 1.71; 95% CI: 1.12 to 2.62; p = 0.01) and severe AVCdensity (adjusted HR: 2.22; 95% CI: 1.40 to 3.52; p = 0.001) also independently predicted overall mortality, even with adjustment for time-dependent AVI.

CONCLUSIONS

This large-scale, multicenter outcomes study of quantitative Doppler echocardiographic and MDCT assessment of AS shows that measuring AVC load provides incremental prognostic value for survival beyond clinical and Doppler echocardiographic assessment. Severe AVC independently predicts excess mortality after AS diagnosis, which is greatly alleviated by AVI. Thus, measurement of AVC by MDCT should be considered for not only diagnostic but also risk-stratification purposes in patients with AS.