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

Diagnostic Value of Aortic Valve Calcification Levels in the Assessment of Low-Gradient Aortic Stenosis

BACKGROUND

In patients with low-gradient aortic stenosis (AS) and low transvalvular flow, dobutamine stress echocardiography (DSE) is recommended to determine AS severity, whereas the degree of aortic valve calcification (AVC) supposedly correlates with AS severity according to current European and American guidelines.

OBJECTIVES

The purpose of this study was to assess the relationship between AVC and AS severity as determined using echocardiography and DSE in patients with aortic valve area <1 cm2 and peak aortic valve velocity <4.0 m/s.

METHODS

All patients underwent DSE to determine AS severity and multislice computed tomography to quantify AVC. Receiver-operating characteristics curve analysis was used to assess the diagnostic value of AVC for AS severity grading as determined using echocardiography and DSE in men and women.

RESULTS

A total of 214 patients were included. Median age was 78 years (25th-75th percentile: 71-84 years) and 25% were women. Left ventricular ejection fraction was reduced (<50%) in 197 (92.1%) patients. Severe AS was diagnosed in 106 patients (49.5%). Moderate AS was diagnosed in 108 patients (50.5%; in 77 based on resting transthoracic echocardiography, in 31 confirmed using DSE). AVC score was high (≥2,000 for men or ≥1,200 for women) in 47 (44.3%) patients with severe AS and in 47 (43.5%) patients with moderate AS. AVC sensitivity was 44.3%, specificity was 56.5%, and positive and negative predictive values for severe AS were 50.0% and 50.8%, respectively. Area under the receiver-operating characteristics curve was 0.508 for men and 0.524 for women.

CONCLUSIONS

Multi-slice computed tomography-derived AVC scores showed poor discrimination between grades of AS severity using DSE and cannot replace DSE in the diagnostic work-up of low-gradient severe AS.

Multimodality imaging for the global evaluation of aortic stenosis: The valve, the ventricle, the afterload

Aortic stenosis (AS) is the most common valvular heart disease growing in parallel to the increment of life expectancy. Besides the valve, the degenerative process affects the aorta, impairing its elastic properties and leading to increased systemic resistance. The composite of valvular and systemic afterload mediates ventricular damage. The first step of a thorough evaluation of AS should include a detailed assessment of valvular anatomy and hemodynamics. Subsequently, the ventricle, and the global afterload should be assessed to define disease stage and prognosis. Multimodality imaging is of paramount importance for the comprehensive evaluation of these three elements. Echocardiography is the cornerstone modality whereas Multi-Detector Computed Tomography and Cardiac Magnetic Resonance provide useful complementary information. This review comprehensively examines the merits of these imaging modalities in AS for the evaluation of the valve, the ventricle, and the afterload and ultimately endeavors to integrate them in a holistic assessment of AS.

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.

Echocardiographic Evaluation of Aortic Stenosis: A Comprehensive Review

Echocardiography represents the most important diagnostic tool in the evaluation of aortic stenosis. The echocardiographic assessment of its severity should always be performed through a standardized and stepwise approach in order to achieve a comprehensive evaluation. The latest technical innovations in the field of echocardiography have improved diagnostic accuracy, guaranteeing a better and more detailed evaluation of aortic valve anatomy. An early diagnosis is of utmost importance since it shortens treatment delays and improves patient outcomes. Echocardiography plays a key role also in the evaluation of all the structural changes related to aortic stenosis. Detailed evaluation of subtle and subclinical changes in left ventricle function has a prognostic significance: scientific efforts have been addressed to identify the most accurate global longitudinal strain cut-off value able to predict adverse outcomes. Moreover, in recent years the role of artificial intelligence is increasingly emerging as a promising tool able to assist cardiologists in aortic stenosis screening and diagnosis, especially by reducing the rate of aortic stenosis misdiagnosis.

Aortic Valvular Stenosis and Heart Failure: Advances in Diagnostic, Management, and Intervention

Up to 30% of patients with aortic stenosis (AS) present with heart failure (HF) symptoms with either reduced or preserved left ventricular ejection fraction. Many of these patients present with a low-flow state, reduced aortic-valve-area (≤1.0 cm²) with low aortic-mean-gradient and aortic-peak-velocity (<40 mm Hg and <4.0 m/s). Thus, determination of true severity is essential for correct management, and multi-imaging evaluation must be performed. Medical treatment of HF is imperative and should be optimized concurrently with the determination of AS-severity. Finally, AS should be treated according to guidelines, keeping in mind that HF and low-flow increase interventions risks.

The diagnostic role of "acceleration time" measurement in patients with classical low flow low gradient aortic stenosis with reduced left ventricular ejection fraction

PURPOSE

In our study, we aimed to assess the role of acceleration time (AT), ejection time (ET), and AT/ET ratio to distinguish between true and pseudo severe AS in patients with classical low flow-low gradient (LF-LG) aortic stenosis (AS) with reduced left ventricular ejection fraction (LVEF).

METHODS

Sixty-seven classical LF-LG AS with reduced LVEF patients who underwent dobutamine stress echocardiography (DSE) were included in the study. According to DSE results, all patients were divided into two groups; true AS and pseudo severe AS. Aortic valve calcium score was measured in patients with inconclusive DSE results. AT and other ejection dynamics (ET and AT/ET) were calculated by taking baseline echocardiographic records into account for all patients. The predictive power of AT and other ejection dynamics were evaluated to estimate true and pseudo severe AS.

RESULTS

According to DSE results, out of 67 patients, 44 (65.7%) was diagnosed as true severe AS. There was a statistically significant relation between baseline AT and true AS [adjusted OR 4.47 (95% CI 1.93-10.4), p = 0.001]. The best cutoff value of AT was measured as 100 msec according to the Youden index. This value had a sensitivity value of 77%, specificity value of 87%, positive predictive value of 92%, and a negative predictive value of 67%.

CONCLUSION

The measurement of AT can predict the DSE outcome and can be used for diagnostic purposes to distinguish between true and pseudo severe AS in classical LF-LG AS patients with reduced LVEF.

Evidence for a sigmoidal flow-to-valve opening relation in low-flow low-gradient aortic stenosis

We analyzed the relationship between flow (Q) and aortic valve opening area (AVA) using a sequence of echocardiographic stress tests of increasing strength. Low-dose dobutamine stress echocardiography (DSE) has been used to differentiate pseudo-severe from true severe aortic stenoses. Because the Q-response to DSE is so variable between individuals, AVA has been projected to a standardized flow (AVA_proj) using linear interpolation. A linear Q-to-AVA relation implies that AVA shows an unconstrained increase. We applied three stress maneuvers of increasing strength to investigate whether AVA shows signs of saturation. We performed an echocardiographic examination at rest, during the passive leg raise maneuver ("PLR"), maximal dobutamine infusion ("Dmax"), and their combination ("Dmax + PLR") in 45 patients with severe low-flow, low-gradient aortic stenosis. We analyzed the effect of the stress maneuver on Q, AVA, valve compliance (VC), and AVA_proj. We also compared the proportion of patients with nonconclusive test (ΔQ < 20%) between stress maneuvers. We computed the Akaike information criterion (AIC) to compare a linear with a saturating function for the Q-AVA relation. Q gradually increased from "PLR" to "Dmax" to "Dmax + PLR" (P < 0.0001), whereas the number of nonconclusive tests concomitantly diminished from n = 35 to n = 3. The stress sequence increased AVA (P < 0.001) but decreased AVA_proj (P = 0.006) and VC (P = 0.005). In the pooled Q-AVA data, the AIC value was lower for the saturating (sigmoidal) model compared with the linear model fitting (-1,593 vs. -1,504). "Dmax + PLR" is capable of reducing the number of nonconclusive DSE tests. With increasing stress strength, the Q-AVA relation progressively flattens, indicating saturation.NEW & NOTEWORTHY The relation between transaortic flow (Q) and aortic valve opening area (AVA) shows a saturation when three different stress maneuvers are used to increase Q as much as possible. This has implications for the assessment of aortic stenosis severity.

Sigmoid isostiffness-lines: An in-vitro model for the assessment of aortic stenosis severity

Introduction

The aortic valve opening area (AVA), used to quantify aortic stenosis severity, depends on the transvalvular flow rate (Q). The currently accepted clinical echocardiographic method assumes a linear relation between AVA and Q. We studied whether a sigmoid model better describes this relation and determined "isostiffness-lines" across a wide flow spectrum, thus allowing building a nomogram for the non-invasive estimation of valve stiffness.

Methods

Both AVA and instantaneous Q (Qinst) were measured at 10 different mean cardiac outputs of porcine aortic valves mounted in a pulsatile flow loop. The valves' cusps were chemically stiffened to obtain three stiffness grades and the procedure was repeated for each grade. The relative stiffness was defined as the ratio between LV work at grade with the added stiffness and at native stiffness grade.AVA peak ¯ corresponding to the selectedQ peak ¯ of the highest 3 and 5 cardiac output values was predicted in K-fold cross-validation using sequentially a linear and a sigmoid model. The accuracy of each model was assessed with the Akaike information criterion (AIC).

Results

The sigmoid model predicted more accuratelyAVA peak ¯ (AIC for prediction of AVA withQ peak ¯ of the 3 highest cardiac output values: -1,743 vs. -1,048; 5 highest cardiac output values: -1,471 vs. -878) than the linear model.

Conclusion

This study suggests that the relation between AVA and Q can be better described by a sigmoid than a linear model. This construction of "isostiffness-lines" may be a useful method for the assessment of aortic stenosis in clinical echocardiography.

Passive Leg Raise Stress Echocardiography in Severe Paradoxical Low-Flow, Low-Gradient Aortic Stenosis

BACKGROUND

Dobutamine stress echocardiography (DSE) is used to increase the transvalvular flow in patients with low-flow, low-gradient aortic stenosis. Dobutamine fails to increase the stroke volume index (SVI) in a third of patients. In this study, we tested whether passive leg raise (PLR) added to dobutamine could increase SVI and transvalvular flow in patients with severe paradoxical low-flow, low-gradient aortic stenosis.

METHODS

Forty-five patients with apparent severe low-flow, low-gradient AS based on traditional measurements were included. Twenty-five were categorized as belonging to the "Paradox"-Group (LVEF≥50%), and twenty to the "LowEF"-Group (LVEF<50% or "classical" low-flow, low-gradient AS) for comparison. A four-step stress echocardiographic exam was performed: resting conditions ("Rest"), PLR alone ("PLR"), maximal dobutamine infusion rate ("Dmax"), and combination of Dmax and PLR ("Dmax+PLR"). AVA, (aortic valve area, cm²) SVI (ml/m2) and mean transvalvular flow (ml/s) were calculated using both, velocity-time-integral (VTI) of LV outflow tract and the Simpson-method. Changes compared to "Rest" and between the stress maneuvers were analysed.

RESULTS

In the "Paradox"-Group, compared to "Rest", LV end-diastolic volume significantly decreased under "Dmax" but was completely restored with "Dmax+PLR" ("Rest", "Dmax", "Dmax+PLR": 61±15 vs 49±18 (p<0.001) vs 61±18 ml (ns)). The smallest SVI-increase in the "Paradox"-Group was observed during "Dmax" ("PLR", "Dmax", "Dmax+PLR": VTI: 38±4 (p<0.001), 36±7 (p=0.019), 41±7 (p<0.001); Simpson: 28±6 (p<0.001), 21±7 (ns), 27±7 ml/m² (ns)). Compared to "Dmax", "Dmax+PLR" was able to achieve a higher SVI (VTI: 36±7 vs 41±7, p<0.001, Simpson: 21±7 vs 27±7 ml/m², p<0.001), and transvalvular flow in the Simpson-method only (179±56 vs 219±56 ml/s, p<0.001) as well as, additionally, a higher mean gradient (34±10 vs 39±12 mmHg, p=0.003) and AVA in the Simpson-method (0.64±0.21 vs 0.73±0.21 cm², p=0.026). In the "LowEF"-Group, only SVI VTI (31±8 vs 35±7 ml/m², p=0.034) and mean gradient (29±12 vs 34±14 mmHg, p=0.003) were higher in "Dmax+PLR". The proportion of patients with SVI VTI ≥ 35 ml/m² and an increase of SVI VTI of more than 20% compared to "Rest" was highest in "Dmax+PLR" in both groups.

CONCLUSIONS

Dobutamine decreases the preload in paradoxical low-flow, low-gradient aortic stenosis. Adding PLR counteracts this effect, resulting in increased SVI and flow (in one method). The combined stress maneuver allowed reclassification of some patients from severe to moderate AS and may therefore be useful in selected cases in this population where the severity is uncertain.

Stress exercise haemodynamic performance and opening reserve of a stented bovine pericardial aortic valve bioprosthesis

OBJECTIVES

Despite unusual high rates of patient-prosthesis mismatch (PPM), excellent midterm clinical outcomes have been reported after surgical aortic valve replacement (SAVR) with the Avalus™ bioprosthetic valve (Medtronic). To elucidate this "PPM conundrum," the Avalus valve haemodynamics were assessed during exercise testing.

METHODS

Of the 148 patients who had undergone SAVR with the Avalus valve at our institution, 30 were randomly selected among those in whom stress test was deemed feasible and underwent a resting transthoracic echocardiography immediately followed by exercise echocardiography. Severe PPM was defined as indexed effective orifice area (iEOA) ≤ 0.65 cm² /m² and moderate PPM as iEOA > 0.65 and ≤ 0.85 cm² /m² . Measured PPM was determined with the use of the measured iEOA at rest or stress, while the estimated PPM was based on the estimated iEOA, derived from the mean EOA reported for each valve size in the manufacturer chart.

RESULTS

Measured EOA significantly increased from rest to peak exercise in all PPM groups (p < .05) and the rates of moderate and severe measured PPM decreased from 40% and 20% to 27% and 0%, respectively. The patients with low-flow state (flow < 250 ml/s) had significantly lower measured rest EOA (p = .03). On the basis of the estimated iEOA, there was no severe PPM and 19 patients had moderate PPM (63.3%), with a significantly lower opening reserve than the patients without estimated PPM (p = .04). The estimated iEOA was more reliably correlated to the measured iEOA at maximal stress than the measured iEOA at rest, especially in patients with a low-flow state.

CONCLUSIONS

This study supports the concept of an opening reserve of the Avalus valve to explain the PPM conundrum and promotes the use of exercise Doppler-echocardiography to complete the assessment of mismatch, especially in patients with a low-flow state. Published estimated EOA seems reliable to predict the haemodynamic performance of the Avalus valve, whether the flow conditions at rest.

Low-Gradient aortic stenosis; the diagnostic dilemma

Low-gradient (LG) aortic valve stenosis (AS) constitutes a significant subset among patients with severe aortic stenosis. This entity represents one of the most challenging heart conditions when it comes to diagnosis and management, mainly because of the discrepancy between the small aortic valve area (≤1.0 cm²) that is considered a severe AS, and low mean transvalvular pressure gradient (<40 mmHg), which is one of the criteria for nonsevere AS. LG AS is divided according to transvalvular aortic flow rate into normal-flow LG AS and low-flow LG (LFLG) AS; the latter category can be divided further according to left ventricular ejection fraction (LVEF) into classical LFLG AS if LVEF is depressed or paradoxical LFLG AS if LVEF is preserved. The primary diagnostic challenge in patients with LG AS is to confirm that AS is truly severe and not pseudosevere, which is assessed mainly by either dobutamine stress echocardiography or multidetector computed tomography. The management of symptomatic true severe LG AS is mainly by aortic valve replacement (AVR), whether surgical or transcatheter approach. Patients with LG severe AS have a generally worse prognosis and higher mortality compared with patients with high-gradient severe AS. Despite the survival benefit of AVR in patients with true severe LG AS, these patients have higher surgical risk post-AVR compared with high-gradient AS patients. Early recognition and correct diagnosis of a patient with LG AS is crucial to improve their mortality and morbidity.

Clinical Value of Stress Transaortic Flow Rate During Dobutamine Echocardiography in Reduced Left Ventricular Ejection Fraction, Low-Gradient Aortic Stenosis: A Multicenter Study

BACKGROUND

Low rest transaortic flow rate (FR) has been shown previously to predict mortality in low-gradient aortic stenosis. However limited prognostic data exists on stress FR during low-dose dobutamine stress echocardiography. We aimed to assess the value of stress FR for the detection of aortic valve stenosis (AS) severity and the prediction of mortality.

METHODS

This is a multicenter cohort study of patients with reduced left ventricular ejection fraction and low-gradient aortic stenosis (aortic valve area <1 cm² and mean gradient <40 mm Hg) who underwent low-dose dobutamine stress echocardiography to identify the AS severity and presence of flow reserve. The outcome assessed was all-cause mortality.

RESULTS

Of the 287 patients (mean age, 75±10 years; males, 71%; left ventricular ejection fraction, 31±10%) over a mean follow-up of 24±30 months there were 127 (44.3%) deaths and 147 (51.2%) patients underwent aortic valve intervention. Higher stress FR was independently associated with reduced risk of mortality (hazard ratio, 0.97 [95% CI, 0.94-0.99]; P=0.01) after adjusting for age, chronic kidney disease, heart failure symptoms, aortic valve intervention, and rest left ventricular ejection fraction. The minimum cutoff for prediction of mortality was stress FR 210 mL/s. Following adjustment to the same important clinical and echocardiographic parameters, among the three criteria of AS severity during stress, ie, the guideline definition of aortic valve area <1cm² and aortic valve mean gradient ≥40 mm Hg, or aortic valve mean gradient ≥40 mm Hg, or the novel definition of aortic valve area <1 cm² at stress FR ≥210 mL/s, only the latter was independently associated with mortality (hazard ratio, 1.72 [95% CI, 1.05-2.82]; P=0.03). Furthermore aortic valve area <1cm² at stress FR ≥210 mL/s was the only severe aortic stenosis criterion that was associated with improved outcome following aortic valve intervention (P<0.001). Guideline-defined stroke volume flow reserve did not predict mortality.

CONCLUSIONS

Stress FR during low-dose dobutamine stress echocardiography was useful for the detection of both AS severity and flow reserve and was associated with improved prediction of outcome following aortic valve intervention.

Manual zur Indikation und Durchführung spezieller echokardiographischer Anwendungen

Das zweite Manual zur Indikation und Durchführung der Echokardiographie bezieht sich auf spezifische Anwendungen der Echokardiographie und besondere Fragestellungen bei speziellen Patientengruppen. Dabei stehen v. a. praktische Aspekte im Vordergrund. Methodisch etabliert sind die transösophageale Echokardiographie, die Stressechokardiographie und die Kontrastechokardiographie. Bei nahezu allen echokardiographischen Untersuchungen spielen aktuell 3‑D-Echokardiographie und Deformationsbildgebung eine Rolle. Das gesamte Spektrum der echokardiographischen Möglichkeiten wird derzeit in Notfall- und Intensivmedizin, bei der Überwachung und Führung von Katheterinterventionen, bei strukturellen Herzerkrankungen, bei herzchirurgischen Operationen, bei der Nachsorge von kardialen Unterstützungssystemen, bei kongenitalen Vitien im Erwachsenenalter und bei der Versorgung von hochinfektiösen Patienten in Pandemiezeiten angewandt. Die diagnostischen Fortschritte der konventionellen und modernen echokardiographischen Anwendungen stehen im Fokus dieses Manuals. Die 3‑D-Echokardiographie zur Charakterisierung der kardialen Morphologie und die Deformationsbildgebung zur Objektivierung der kardialen Funktion sind bei vielen Indikationen im klinischen Alltag etabliert. Die Stressechokardiographie zur Ischämie‑, Vitalitäts- und Vitiendiagnostik, die Bestimmung der koronaren Flussreserve und die Kontrastechokardiographie bei der linksventrikulären Wandbewegungsanalyse und kardialen Tumordetektion finden zunehmend klinische Anwendung. Wie für die konventionelle Echokardiographie im ersten Manual der Echokardiographie 2009 beschrieben, erfordert der Einsatz moderner echokardiographischer Verfahren die standardisierte Dokumentation und Akquisition bestimmter Bildsequenzen bei optimierter Geräteeinstellung, da korrekte und reproduzierbare Auswertungen nur bei guter Bildqualität möglich sind.

Resting echocardiographic predictors for true-severe aortic stenosis in patients with low-gradient severe aortic stenosis: A dobutamine stress echocardiography study

OBJECTIVE

Dobutamine stress echocardiography (DSE) is not always feasible in patients with low-gradient severe aortic stenosis (LG-SAS), and there are limited data available on the resting echocardiographic predictors for true-severe aortic stenosis (TSAS). This study investigated resting echocardiographic predictors for TSAS.

METHODS

Clinical data of 106 LG-SAS patients who underwent DSE were retrospectively analyzed. LG-SAS was defined as an aortic valve area index (AVAi) < .6 cm² /m² , and a mean AV pressure gradient < 40 mm Hg. The velocity ratio (VR) was calculated as the peak left ventricular outflow tract velocity/peak AV velocity. TSAS was defined as a projected AVAi < .6 cm² /m² .

RESULTS

The mean age was 79.3 ± 7.3 years, and 45 (42.5%) were men. The resting AV data were as follows: AVAi, .50 ± .07 cm² /m² ; mean AV pressure gradient, 23.0 ± 7.4 mm Hg; and VR, .25 ± .05. The projected AVAi was .58 ± .09 cm² /m² , and TSAS was documented in 65 (61.3%) patients. In multivariate analysis, the independent predictors of TSAS were AVAi (p = 0.012) and VR (p = 0.004) with respective best cut-off values of .52 cm² /m² and .25 on receiver-operating characteristic curve analysis. According to incremental numbers of the predictors, correct classification percentages of TSAS significantly increased with the Cochran-Armitage trend test (16.2% in no predictors, 65.2% in one predictor, and 95.7 % in two predictors; p < 0.001).

CONCLUSIONS

Resting AVAi and VR were independent predictors of TSAS in LG-SAS patients. The true severity might be predictable using the combination of resting parameters.

Comparison of transvalvular flow rate in aortic stenosis subtypes

OBJECTIVES

Evaluate ET and TVFR in normal patients, PLFLGAS, LGLFAS, and classic pre and post TAVR.

BACKGROUND

Severe aortic stenosis (AS) is defined echocardiographically. Generating a pressure gradient to meet diagnostic criteria is dependent on left ventricular contractility, stroke volume, and ejection time.  Abnormalities in these decrease the mean pressure gradient across the valve creating pathology termed low flow, low gradient AS. This occurs in two subtypes, low ejection fraction LFLGAS and paradoxical LFLGAS (PLFLGAS), in which EF is normal but stroke volume is < 35 ml/m² . Paradoxical LFLGAS is difficult to diagnose and does not have a confirmatory echocardiographic parameter. Transvalvular flow rate (TVFR), which is defined as stroke volume divided by the ejection time, provides a direct measure of flow across the aortic valve.

METHODS

A retrospective study of patients who underwent transcatheter aortic valve replacement (TAVR) at the University of Cincinnati Medical Center between 2016 and 2019 was performed. Patients were classified by AS subtype. ET and TVFR were measured pre and post TAVR and statistically compared using SPSS statistics software and ANOVA analysis.

RESULTS

Pre TAVR TVFR in the normal population, severe AS population, and LFLGAS were not significantly different. The pre TAVR TVFR in paradoxical LFLGAS patients was significantly lower than other groups. TVFR improved to the greatest degree post TAVR in PLFLGAS but did not meet statistical significance.

CONCLUSIONS

The significantly lower TVFR demonstrated in PLFLGAS provides a comprehensive, direct measurement of aortic valve hemodynamics and PLFLGAS pathology and can aid in diagnosis.

Diagnosis and Management of Aortic Valve Stenosis: The Role of Non-Invasive Imaging

Aortic stenosis is the most common heart valve disease necessitating surgical or percutaneous intervention. Imaging has a central role for the initial diagnostic work-up, the follow-up and the selection of the optimal timing and type of intervention. Referral for aortic valve replacement is currently driven by the severity and by the presence of aortic stenosis-related symptoms or signs of left ventricular systolic dysfunction. This review aims to provide an update of the imaging techniques and seeks to highlight a practical approach to help clinical decision making.

Rational and design of the ROTAS study: a randomized study for the optimal treatment of symptomatic patients with low-gradient severe aortic valve stenosis and preserved left ventricular ejection fraction

AIMS

Fifteen to thirty percentage of patients with severe aortic stenosis (AS) have preserved left ventricular ejection fraction (LVEF) and a discordant AS pattern at Doppler echocardiography, which is characterized by a small (<1 cm2) aortic area and low mean aortic gradient (<40 mmHg). The 'Randomized study for the Optimal Treatment of symptomatic patients with low-gradient severe Aortic Stenosis and preserved left ventricular ejection fraction' (ROTAS trial) aims at demonstrating the superiority of aortic valve replacement vs. a 'watchful waiting strategy' in symptomatic patients with low-gradient (LS), severe AS, and preserved LVEF, stratified according to indexed stroke volume, in terms of all-cause mortality or cardiovascular-related hospitalization during follow-up (FU).

METHODS AND RESULTS

The ROTAS trial will be a multicentre randomized non-blinded study involving 16 reference centres. AS severity will be confirmed by a multimodality approach (rest and stress echocardiography, calcium scoring, and cardiac magnetic resonance imaging for optimally characterize the population), which could provide important inputs to improve the pathophysiological understanding of this complex disease. Well-characterized patients will be randomized according to the management strategy. The primary endpoint will be the occurrence of all-cause mortality or cardiac related-hospitalizations during 2-year FU. One hundred and eighty subjects per group will be included.

CONCLUSION

The management of patients with LS severe AS and preserved LVEF is largely debated. ROTAS trial will allow a comprehensive evaluation of this particular pattern of AS and will establish which is the most appropriate management of these patients.

Updated knowledge and practical implementations of stress echocardiography in ischemic and non-ischemic cardiac diseases: an expert consensus of the Working Group of Echocardiography of the Hellenic Society of Cardiology

Stress echocardiography (SE) is a well-established and valid technique, widely-used for the diagnostic evaluation of patients with ischemic and non-ischemic cardiac diseases. This statement of the Echocardiography Working Group of the Hellenic Society of Cardiology summarizes the consensus of the writing group regarding the applications of SE, based on the expertise of their members and on a critical review of current medical literature. The main objectives of the consensus document include a comprehensive review of SE methodology and training, focusing on the preparation, the protocols used and the analysis of the SE images and an updated, evidence-based knowledge about SE applications on ischemic and non-ischemic heart diseases, such as in cardiomyopathies, heart failure and valvular heart disease.

Moderate Aortic Stenosis in Patients With Heart Failure and Reduced Ejection Fraction

BACKGROUND

The study investigators previously reported that moderate aortic stenosis (AS) is associated with a poor prognosis in patients with heart failure (HF) with reduced left ventricular ejection fraction (LVEF) (HFrEF). However, the respective contribution of moderate AS versus HFrEF to the outcomes of these patients is unknown.

OBJECTIVES

This study sought to determine the impact of moderate AS on outcomes in patients with HFrEF.

METHODS

The study included 262 patients with moderate AS (aortic valve area >1.0 and <1.5 cm²; and peak aortic jet velocity >2 and <4 m/s, at rest or after dobutamine stress echocardiography) and HFrEF (LVEF <50%). These patients were matched 1:1 for sex, age, estimated glomerular filtration rate, New York Heart Association functional class III to IV, presence of diabetes, LVEF, and body mass index with patients with HFrEF but no AS (i.e., peak aortic jet velocity <2 m/s). The endpoints were all-cause mortality and the composite of death and HF hospitalization.

RESULTS

A total of 262 patients with HFrEF and moderate AS were matched with 262 patients with HFrEF and no AS. Mean follow-up was 2.9 ± 2.2 years. In the moderate AS group, mean aortic valve area was 1.2 ± 0.2 cm², and mean gradient was 14.5 ± 4.7 mm Hg. Moderate AS was associated with an increased risk of mortality (hazard ratio [HR]: 2.98; 95% confidence interval [CI]: 2.08 to 4.31; p < 0.0001) and of the composite of HF hospitalization and mortality (HR: 2.34; 95% CI: 1. 72 to 3.21; p < 0.0001). In the moderate AS group, aortic valve replacement (AVR) performed in 44 patients at a median follow-up time of 10.9 ± 16 months during follow-up was associated with improved survival (HR: 0.59; 95% CI: 0.35 to 0.98; p = 0.04). Notably, surgical AVR was not significantly associated with improved survival (p = 0.92), whereas transcatheter AVR was (HR: 0.43; 95% CI: 0.18 to 1.00; p = 0.05).

CONCLUSIONS

In this series of patients with HFrEF, moderate AS was associated with a marked incremental risk of mortality. AVR, and especially transcatheter AVR during follow-up, was associated with improved survival in patients with HFrEF and moderate AS. These findings provide support to the realization of a randomized trial to assess the effect of early transcatheter AVR in patients with HFrEF and moderate AS.

Predictors of true-severe classical low-flow low-gradient aortic stenosis at resting echocardiography

BACKGROUND

Classical low-flow, low-gradient (LF/LG) aortic stenosis (AS) is subclassified into a true-severe (TS) and a pseudo-severe (PS) subform using low-dose dobutamine stress echocardiography (DSE). In clinical practice a resting peak jet velocity (Vmax) >3.5 m/s or a mean transvalvular gradient (MPG) >35 mmHg suggests the presence of TS classical LF/LG AS, but there is no data to support this. The aim of this study was therefore to investigate whether a resting Vmax >3.5 m/s or MPG >35 mmHg reliably predicted diagnosis of TS classical LF/LG AS.

METHODS

One hundred (100) consecutive patients with classical LF/LG AS were prospectively recruited. All patients underwent DSE for subcategorization. The impact of Vmax and MPG for the presence of the TS subform were analyzed.

RESULTS

TS classical LF/LG AS was diagnosed in 72 patients. Resting Vmax and resting MPG predicted true-severity with an ROC-AUC of 0.737 (95%CI: 0.635-0.838; p < 0.001) and 0.725 (95%CI: 0.615-0.834; p < 0.001), respectively. The optimal positive predictive values (PPV) for the diagnosis of TS classical LF/LG AS were obtained with a resting Vmax >3.5 m/s or resting MPG >35 mmHg. In a multivariate logistic regression analysis, Vmax >3.5 m/s was independently associated with a 5.33-fold odds-ratio of TS classical LF/LG AS (OR 5.33; 95%CI: 1.34-21.18, p = 0.018).

CONCLUSIONS

TS classical LF/LG AS can be reliably predicted by a resting Vmax >3.5 m/s or a resting MPG >35 mmHg. Further imaging for subclassification is not needed in this situation.

Comparison of Early Surgical or Transcatheter Aortic Valve Replacement Versus Conservative Management in Low-Flow, Low-Gradient Aortic Stenosis Using Inverse Probability of Treatment Weighting: Results From the TOPAS Prospective Observational Cohort Study

Background No randomized comparison of early (ie, ≤3 months) aortic valve replacement (AVR) versus conservative management or of transcatheter AVR (TAVR) versus surgical AVR has been conducted in patients with low-flow, low-gradient (LFLG) aortic stenosis (AS). Methods and Results A total of 481 consecutive patients (75±10 years; 71% men) with LFLG AS (aortic valve area ≤0.6 cm2/m2 and mean gradient <40 mm Hg), 72% with classic LFLG and 28% with paradoxical LFLG, were prospectively recruited in the multicenter TOPAS (True or Pseudo Severe Aortic Stenosis) study. True-severe AS or pseudo-severe AS was adjudicated by flow-independent criteria. During follow-up (median [IQR] 36 [11-60] months), 220 patients died. Using inverse probability of treatment weighting to address the bias of nonrandom treatment assignment, early AVR (n=272) was associated with a major overall survival benefit (hazard ratio [HR], 0.34 [95% CI, 0.24-0.50]; P<0.001). This benefit was observed in patients with true-severe AS but also with pseudo-severe AS (HR, 0.38 [95% CI, 0.18-0.81]; P=0.01), and in classic (HR, 0.33 [95% CI, 0.22-0.49]; P<0.001) and paradoxical LFLG AS (HR, 0.42 [95% CI, 0.20-0.92]; P=0.03). Compared with conservative management in the conventional multivariate model, trans femoral TAVR was associated with the best survival (HR, 0.23 [95% CI, 0.12-0.43]; P<0.001), followed by surgical AVR (HR, 0.36 [95% CI, 0.23-0.56]; P<0.001) and alternative-access TAVR (HR, 0.51 [95% CI, 0.31-0.82]; P=0.007). In the inverse probability of treatment weighting model, trans femoral TAVR appeared to be superior to surgical AVR (HR [95% CI] 0.28 [0.11-0.72]; P=0.008) with regard to survival. Conclusions In this large prospective observational study of LFLG AS, early AVR appeared to confer a major survival benefit in both classic and paradoxical LFLG AS. This benefit seems to extend to the subgroup with pseudo-severe AS. Our findings suggest that TAVR using femoral access might be the best strategy in these patients. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT01835028.

Multimodality Imaging for Discordant Low-Gradient Aortic Stenosis: Assessing the Valve and the Myocardium

Aortic stenosis (AS) is a disease of the valve and the myocardium. A correct assessment of the valve disease severity is key to define the need for aortic valve replacement (AVR), but a better understanding of the myocardial consequences of the increased afterload is paramount to optimize the timing of the intervention. Transthoracic echocardiography remains the cornerstone of AS assessment, as it is universally available, and it allows a comprehensive structural and hemodynamic evaluation of both the aortic valve and the rest of the heart. However, it may not be sufficient as a significant proportion of patients with severe AS presents with discordant grading (i.e., an AVA ≤ 1 cm² and a mean gradient <40 mmHg) which raises uncertainty about the true severity of AS and the need for AVR. Several imaging modalities (transesophageal or stress echocardiography, computed tomography, cardiovascular magnetic resonance, positron emission tomography) exist that allow a detailed assessment of the stenotic aortic valve and the myocardial remodeling response. This review aims to provide an updated overview of these multimodality imaging techniques and seeks to highlight a practical approach to help clinical decision making in the challenging group of patients with discordant low-gradient AS.

Haemodynamic Patterns of Severe Aortic Stenosis

The authors present up-to-date review of clinical pathophysiology of aortic stenosis (AS) based on differentiation of its haemodynamic patterns, and some actual issues of instrumental diagnostics and classification of AS. The variety of clinical presentations of AS is based on diverse combination of pathological changes of haemodynamics. In Russian cardiology, there is no clear pathophysiological classification of AS despite of its relevance under the progress of surgical and transcatheter treatment of AS. The authors suggest the pilot haemodynamic classification of AS which includes 6 types (0-5) based on different combination of the following variables: left ventricle ejection fraction, stroke volume, mean aortic systolic pressure gradient. Severe AS with low transaortic pressure gradient in patients with depressed systolic function of the left ventricle (so called «low flow-low» gradient phenomenon) is referred to as the most frequent, classical haemodynamic pattern of low-gradient AS. The prevalence of this variant is about 10% among European population of patients with severe AS. The inconsistence between aortic valve area and mean pressure gradient is as common as in 35-40% of patients with AS, however, in 30-50% of these cases, AS is not severe. Severe AS is a surgical disease that should be treated in a surgical way in all patients but those in whom predicted risk overbalances potential benefits of the procedure. The use of integrated clinical and instrumental approach for identification of a true sever AS is the matter of great concern, as both overestimation and underestimation can misguide the clinical decision-making process. Verification of severe AS in patients with classical and paradoxical low flow-low gradient AS with specific indications for surgical treatment regarded is further emphasized in the paper. Since transcatheter aortic valve implantation has become a commonly recognized alternative to surgical aortic valve replacement, its role in the treatment of severe AS with different haemodynamic patterns is also discussed. The authors stress on the necessity of using tailored approach for treatment of AS regarding different clinical and pathophysiological scenarios: high gradient AS with preserved ejection fraction, classical and paradoxical low flow-low gradient AS.

Reclassification of aortic stenosis by fusion of echocardiography and computed tomography in low-gradient aortic stenosis

Background

The integration of computed tomography (CT)-derived left ventricular outflow tract area into the echocardiography-derived continuity equation results in the reclassification of a significant proportion of patients with severe aortic stenosis (AS) into moderate AS based on aortic valve area indexed to body surface area determined by fusion imaging (fusion AVA_i). The aim of this study was to evaluate AS severity by a fusion imaging technique in patients with low-gradient AS and to compare the clinical impact of reclassified moderate AS versus severe AS.

Methods

We included 359 consecutive patients who underwent transcatheter aortic valve implantation for low-gradient, severe AS at two academic institutions and created a joint database. The primary endpoint was a composite of all-cause mortality and rehospitalisations for heart failure at 1 year.

Results

Overall, 35% of the population (n = 126) were reclassified to moderate AS [median fusion AVAi 0.70 (interquartile range, IQR 0.65–0.80) cm²/m²] and severe AS was retained as the classification in 65% [median fusion AVAi 0.49 (IQR 0.43–0.54) cm²/m²]. Lower body mass index, higher logistic EuroSCORE and larger aortic dimensions characterised patients reclassified to moderate AS. Overall, 57% of patients had a left ventricular ejection fraction (LVEF) <50%. Clinical outcome was similar in patients with reclassified moderate or severe AS. Among patients reclassified to moderate AS, non-cardiac mortality was higher in those with LVEF <50% than in those with LVEF ≥50% (log-rank p = 0.029).

Conclusions

The integration of CT and transthoracic echocardiography to obtain fusion AVAi led to the reclassification of one third of patients with low-gradient AS to moderate AS. Reclassification did not affect clinical outcome, although patients reclassified to moderate AS with a LVEF <50% had worse outcomes owing to excess non-cardiac mortality.

Assessing the true severity of low-gradient aortic stenosis using resting echocardiography

BACKGROUND

Dobutamine stress echocardiography (DSE) is required to determine whether low-gradient aortic stenosis (AS) with a small aortic valve area (AVA) is truly severe. The purpose of the present study was to evaluate the usefulness of ejection dynamics parameters at resting echocardiography for predicting the result of DSE performed in patients with low-gradient AS.

METHODS

The results of resting echocardiography and DSE performed on 51 AS patients with low mean-gradient (<40 mmHg) and small indexed AVA (<0.60 cm²/m²) were retrospectively reviewed. Acceleration time (AT) and the ratio of AT to ejection time (ET) were measured on the recorded images. True-severe AS was defined as that with indexed projected AVA < 0.60 cm²/m².

RESULTS

Twenty-six (51%) patients had true-severe AS, while 22 (43%) patients had preserved left ventricular ejection fraction (≥50%). Baseline indexed AVA and AT/ET were independently associated with indexed projected AVA at DSE. AT/ET was the only independent determinant of valve compliance. Indexed AVA ≤ 0.493 cm²/m² and AT/ET > 0.334 at baseline had sensitivities of 69% and 65% and specificities of 84% and 84%, respectively, for predicting true-severe AS. The presence of either indexed AVA ≤ 0.493 cm²/m² or AT/ET > 0.334 had a higher sensitivity (88%), and their co-occurrence had a higher specificity (100%).

CONCLUSIONS

Indexed projected AVA at DSE was predicted by AT/ET, which represented valve compliance, along with indexed AVA. The true severity of low-gradient AS can be screened using a combination of resting indexed AVA and AT/ET without performing DSE.

Discordant Echocardiographic Grading in Low Gradient Aortic Stenosis (DEGAS Study) From the Italian Society of Echocardiography and Cardiovascular Imaging Research Network: Rationale and Study Design

Background

Low-gradient aortic stenosis (LG-AS) is characterized by the combination of an aortic valve area compatible with severe stenosis and a low transvalvular mean gradient with low-flow state (i.e., indexed stroke volume <35 mL/m²) in the presence of reduced (classical low-flow AS) or preserved (paradoxical low-flow AS) ejection fraction. Furthermore, the occurrence of a normal-flow LG-AS is still advocated by many authors. Within this diagnostic complexity, the diagnosis of severe AS remains challenging.

Objective

The general objective of the Discordant Echocardiographic Grading in Low-gradient AS (DEGAS Study) study will be to assess the prevalence of true severe AS in this population and validate new parameters to improve the assessment and the clinical decision-making in patients with LG-AS.

Methods and Analyses

The DEGAS Study of the Italian Society of Echocardiography and Cardiovascular Imaging is a prospective, multicenter, observational diagnostic study that will enroll consecutively adult patients with LG-AS over 2 years. AS severity will be ideally confirmed by a multimodality approach, but only the quantification of calcium score by multidetector computed tomography will be mandatory. The primary clinical outcome variable will be 12-month all-cause mortality. The secondary outcome variables will be (i) 30-day mortality (for patients treated by Surgical aortic valve replacement or TAVR); (ii) 12-month cardiovascular mortality; (iii) 12-month new major cardiovascular events such as myocardial infarction, stroke, vascular complications, and rehospitalization for heart failure; and (iv) composite endpoint of cardiovascular mortality and hospitalization for heart failure. Data collection will take place through a web platform (REDCap), absolutely secure based on current standards concerning the ethical requirements and data integrity.

Echocardiographic findings on aortic stenosis: an observational, prospective, and multi-center registry

BACKGROUND

The aim of this aortic stenosis registry was to investigate the changes of routine echocardiographic indices and strain in patients with moderate-to-severe aortic stenosis over a 6-month follow-up period.

METHODS

Our aortic stenosis registry is observational, prospective, multicenter registry of nine countries, with 197 patients with aortic valve area less than 1.5 cm². The enrolment took place from January to August 2017. We excluded patients with uncontrolled atrial arrhythmias, pulmonary hypertension or cardiomyopathies, as well as those with hemodynamically significant valvular disease other than aortic stenosis. We included patients who did not require intervention and who had a complete follow-up study.

RESULTS

In patients with preserved ejection fraction, left ventricular mass has significantly increased between baseline and follow-up studies (218 ± 34 grams vs 253 ± 29 grams, p = 0.02). However, when indexed to body surface area, there was no significant difference. Left ventricular global longitudinal strain significantly decreased (-19.7 ± -4.8 vs (-16.4 vs -3.8, p = 0.01). Left atrial volume was significantly higher at follow-up (p = 0.035). Right ventricular basal diameter and mid-cavity diameter were greater at the follow-up (p = 0.04 and p = 0.035, respectively). Patients with low-flow low-gradient aortic stenosis had significantly lower global longitudinal strain (-12.3% ± -3.9% vs -19.7% ± -4.8%, p = 0.01).

CONCLUSION

Left atrial dilatation is one of the first changes to take place in low-flow low-gradient aortic stenosis patients even when left ventricular dimensions and function remains intact. Global longitudinal strain is an important determinant of left ventricular systolic and diastolic dysfunction and right ventricular function is an important parameter of aortic stenosis assessment. Accordingly, our registry has further shed the light on these indices role as multisite follow-up of aortic stenosis.

"Pure" severe aortic stenosis without concomitant valvular heart diseases: echocardiographic and pathophysiological features

Purpose

In echocardiography the severity of aortic stenosis (AS) is defined by effective orifice area (EOA), mean pressure gradient (mPG_AV) and transvalvular flow velocity (maxV_AV). The hypothesis of the present study was to confirm the pathophysiological presence of combined left ventricular hypertrophy (LVH), diastolic dysfunction (DD) and pulmonary artery hypertension (PAH) in patients with “pure” severe AS.

Methods and Results

Patients (n = 306) with asymptomatic (n = 133) and symptomatic (n = 173) “pure” severe AS (mean age 78 ± 9.5 years) defined by indexed EOA < 0.6 cm² were enrolled between 2014 and 2016. AS patients were divided into 4 subgroups according to mPG_AV and indexed left ventricular stroke volume: low flow (LF) low gradient (LG)-AS (n = 133), normal flow (NF) LG-AS (n = 91), LF high gradient (HG)-AS (n = 21) and NFHG-AS (n = 61). Patients with “pure” severe AS showed mean mPG_AV of 31.7 ± 9.1 mmHg and mean maxV_AV of 3.8 ± 0.6 m/s. Only 131 of 306 patients (43%) exhibited mPG_AV > 40 mmHg and maxV_AV > 4 m/s documenting incongruencies of the AS severity assessment by Doppler echocardiography. LVH was documented in 81%, DD in 76% and PAH in 80% of AS patients. 54% of “pure” AS patients exhibited all three alterations. Ranges of mPG_AV and maxV_AV were higher in patients with all three alterations compared to patients with less than three. 224 (73%) patients presented LG-conditions and 82 (27%) HG-conditions. LVH was predominant in NF-AS (p = 0.014) and PAH in LFHG-AS (p = 0.014). Patients’ treatment was retrospectively assessed (surgery: n = 100, TAVI: n = 48, optimal medical treatment: n = 156).

Conclusion

In patients with “pure” AS according to current guidelines the presence of combined LVH, DD and PAH as accepted pathophysiological sequelae of severe AS cannot be confirmed. Probably, the detection of these secondary cardiac alterations might improve the diagnostic algorithm to avoid overestimation of AS severity.

Moderate Aortic Stenosis and Heart Failure With Reduced Ejection Fraction: Can Imaging Guide Us to Therapy?

Clinical management of patients with only moderate aortic stenosis (AS) but symptoms of heart failure with a reduced left ventricular ejection fraction (HFrEF) is challenging. Current guidelines recommend clinical surveillance with multimodality imaging; aortic valve replacement (AVR) is deferred until the stenosis becomes severe. Given the known benefits of afterload reduction in management of patients with HFrEF, it has been hypothesized that AVR may be beneficial in patients with only moderate AS who present with HFrEF. In this article, we first review the current approach for management of patients with moderate AS and HFrEF based on close clinical and imaging surveillance with AVR delayed until AS is severe. We then discuss the case for transcatheter AVR (TAVR) earlier in the disease course, when AS is moderate, based on stress echocardiographic data. We conclude with a detailed summary of the TAVR UNLOAD (Transcatheter Aortic Valve Replacement to UNload the Left Ventricle in Patients With ADvanced Heart Failure) trial, in which patients with moderate AS and HFrEF are randomized to guideline-directed heart failure therapy alone versus guideline-directed heart failure therapy plus TAVR.

Significance of echocardiographic evaluation for transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) is widely accepted as an alternative to surgical aortic valve replacement (SAVR) for the treatment of severe aortic stenosis (AS). Existing scientific evidence demonstrates that TAVI is superior to SAVR, and it is expected that indications for the clinical applications of TAVI will be expanded in the future. Echocardiography plays a key role in perioperative assessment of patients undergoing TAVI. Preprocedural echocardiographic evaluation is important to determine the severity of AS in addition to patients' anatomical suitability for TAVI. Furthermore, echocardiography is essential for intraoperative guidance, assessment of complications, postoperative evaluation, and prognostic prediction. Inaccurate echocardiographic measurements and evaluation can lead to less-than-optimal/inappropriate treatment strategies in patients with AS. Therefore, a thorough understanding of the limitations of echocardiographic evaluation is important. This review summarizes the role of echocardiographic evaluation in patients undergoing TAVI.

Clinical application of stress echocardiography for valvular heart disease

Stress echocardiography is widely used to assess several cardiovascular diseases, including ischemic heart disease, valvular heart disease (VHD), heart failure, congenital heart disease, and pulmonary hypertension. In valvular heart disease with asymptomatic severe or symptomatic non-severe status, stress echocardiography plays a central role in the management. As of 2017, the updated American College of Cardiology/American Heart Association and European Society of Cardiology/European Association for Cardio-Thoracic Surgery VHD guidelines recommended stress testing to (1) confirm symptoms and (2) evaluate the hemodynamic response to exercise. In patients with undetermined VHD severity in the presence of low-flow status, it can also be helpful to determine whether the VHD is severe based on flow-dependent changes in response to stress. The clinical indications of stress echocardiography in VHD have expanded with growing evidence for prognosis and being an early marker for interventions. As a result, demand has increased in major cardiology societies for the standardization of stress echocardiography in VHD. Echocardiographic centers should be aware of the clinical potential of stress echocardiography to ensure its optimal application and performance in VHD. This article reviews the clinical application of stress echocardiography, including dobutamine, semisupine bicycle, treadmill, and leg-positive pressure for VHD patient management, and focuses on the current consensus regarding the use of stress echocardiography in VHD. Stress echocardiography is safe and should be encouraged, especially in heart valve clinics, to understand the complex mechanism in asymptomatic patients.

Contemporary Imaging of Aortic Stenosis

Degenerative or fibrocalcific aortic stenosis (AS) is now the most common native valvular heart disease assessed and managed by cardiologists in developed countries. Transthoracic echocardiography remains the quintessential imaging modality for the non-invasive characterisation of AS due to its widespread availability, superior assessment of flow haemodynamics, and a wealth of prognostic data accumulated over decades of clinical utility and research applications. With expanding technologies and increasing availability of treatment options such as transcatheter aortic valve replacements, in addition to conventional surgical approaches, accurate and precise assessment of AS severity is critical to guide decisions for and timing of interventions. Despite clear guideline echocardiographic parameters demarcating severe AS, discrepancies between transvalvular velocities, gradients, and calculated valve areas are commonly encountered in clinical practice. This often results in diagnostically challenging cases with significant implications. Greater emphasis must be placed on the quality of performance of basic two dimensional (2D) and Doppler measurements (attention to detail ensuring accuracy and precision), incorporating ancillary haemodynamic surrogates, understanding study- or patient-specific confounders, and recognising the role and limitations of stress echocardiography in the subgroups of low-flow low-gradient AS. A multiparametric approach, along with the incorporation of multimodality imaging (cardiac computed tomography or magnetic resonance imaging) in certain scenarios, is now mandatory to avoid incorrect misclassification of severe AS. This is essential to ensure appropriate selection of patients who would most benefit from interventions on the aortic valve to relieve the afterload mismatch resulting from truly severe valvular stenosis.

Dobutamine Stress Echocardiography in Low-Flow, Low-Gradient Aortic Stenosis: Flow Reserve Does Not Matter Anymore

See Article by Sato et al.

Stress echocardiography in valvular heart disease

INTRODUCTION

The management of patients with heart valve disease can be complex. Patients may have symptoms disproportionate to the severity or the severity may be unclear. In addition, the optimal timing of intervention in patients with severe disease may be controversial. Areas covered: This article examines the role of stress echocardiography for assessment of patients with low-flow, low-gradient aortic stenosis, asymptomatic severe valve disease and patients where symptoms are discordant to the resting severity of valve disease. Expert commentary: Stress echocardiography helps clinicians determine the true severity of valve disease and may identify the cause of symptoms in patients with only mild/moderate disease. The data provided by stress echocardiography will help determine the appropriate management strategy and the correct timing of intervention.

Value of low-dose dobutamine stress echocardiography on defining true severe low gradient aortic stenosis in patients with preserved left ventricular ejection fraction

Low-dose dobutamine stress echocardiography (DSE) is a valuable tool to distinguish true-severe (TS) from pseudo-severe (PS) low gradient aortic valve stenosis (LGAS) in patients with reduced left ventricular ejection fraction (LVEF). However, only scanty studies reported the clinical utility of DSE in differentiating TS-LGAS patients with preserved LVEF. We investigated the clinical utility of DSE in LGAS patients with preserved LVEF and the echocardiographic determinants suggestive of TS-LGAS. 130 consecutive LGAS patients [indexed aortic valve area (AVA) ≤ 0.6cm²/m² and mean trans-aortic pressure gradient (PG_mean) < 40mmHg] with preserved (≥ 50%, n = 63) and reduced (< 50%, n = 67) LVEF were included. DSE defined TS-LGAS (projected AVA ≤ 1 cm²) in 61.2% patients with reduced LVEF and in 68.3% patients with preserved LVEF. Multivariate logistic regression analysis showed that baseline AVA was an independent determinant of TS-LGAS both in LVEF ≥ 50% (OR 0.45, P = 0.004) and LVEF < 50% groups (OR 0.55, P = 0.005). Reduced septal and lateral mitral annular plane systolic excursion (MAPSE, OR 0.72 and 0.75, P = 0.013 and 0.016) and septal TDI-s´ were significantly associated with TS-LGAS in patients with LVEF ≥ 50%. Higher systolic pulmonary artery pressure (SPAP, OR 1.43, P = 0.045) was associated with TS-LGAS in patients with LVEF < 50%. DSE is useful to define TS-LGAS also in patients with preserved LVEF. Lower baseline AVA values are linked with TS-LGAS in both patients with reduced and preserved LVEF. Reduced MAPSE and septal TDI-s´ are suggestive of TS-LGAS in patients with preserved LVEF, while higher SPAP is associated with TS-LGAS in patients with reduced LVEF.