Transvalvular Flow Rate Determines Prognostic Value of Aortic Valve Area in Aortic Stenosis

Predictors of outcome in patients with moderate mixed aortic valve disease

OBJECTIVES

Grading the severity of moderate mixed aortic stenosis and regurgitation (MAVD) is challenging and the disease poorly understood. Identifying markers of haemodynamic severity will improve risk stratification and potentially guide timely treatment. This study aims to identify prognostic haemodynamic markers in patients with moderate MAVD.

METHODS

Moderate MAVD was defined as coexisting moderate aortic stenosis (aortic valve area (AVA) 1.0-1.5 cm2) and moderate aortic regurgitation (vena contracta (VC) 0.3-0.6 cm). Consecutive patients diagnosed between 2015 and 2019 were included from a multicentre registry. The primary composite outcome of death or heart failure hospitalisation was evaluated among these patients. Demographics, comorbidities, echocardiography and treatment data were assessed for their prognostic significance.

RESULTS

207 patients with moderate MAVD were included, aged 78 (66-84) years, 56% male sex, AVA 1.2 (1.1-1.4) cm2 and VC 0.4 (0.4-0.5) cm. Over a follow-up of 3.5 (2.5-4.7) years, the composite outcome was met in 89 patients (43%). Univariable associations with the primary outcome included older age, previous myocardial infarction, previous cerebrovascular event, atrial fibrillation, New York Heart Association >2, worse renal function, tricuspid regurgitation ≥2 and mitral regurgitation ≥2. Markers of biventricular systolic function, cardiac remodelling and transaortic valve haemodynamics demonstrated an inverse association with the primary composite outcome. In multivariable analysis, peak aortic jet velocity (Vmax) was independently and inversely associated with the composite outcome (HR: 0.63, 95% CI 0.43 to 0.93; p=0.021) in an adjusted model along with age (HR: 1.05, 95% CI 1.03 to 1.08; p<0.001), creatinine (HR: 1.002, 95% CI 1.001 to 1.003; p=0.005), previous cerebrovascular event (85% vs 42%; HR: 3.04, 95% CI 1.54 to 5.99; p=0.001) and left ventricular ejection fraction (LVEF) (HR: 0.97, 95% CI 0.95 to 0.99; p=0.007). Patients with Vmax ≤2.8 m/s and LVEF ≤50% (n=27) had the worst outcome compared with the rest of the population (72% vs 41%; HR: 3.87, 95% CI 2.20 to 6.80; p<0.001).

CONCLUSIONS

Patients with truly moderate MAVD have a high incidence of death and heart failure hospitalisation (43% at 3.5 (2.5-4.7) years). Within this group, a high-risk group characterised by disproportionately low aortic Vmax (≤2.8 m/s) and adverse remodelling (LVEF ≤50%) have the worst outcomes.

Normal-Flow Low-Gradient Aortic Stenosis: Comparing the U.S. and European Guidelines

Patients with normal-flow low-gradient (NFLG) severe aortic stenosis present both diagnostic and management challenges, with debate about the whether this represents true severe stenosis and the need for valve replacement. Studies exploring the natural history without intervention have shown similar outcomes of patients with NFLG severe aortic stenosis to those with moderate aortic stenosis and better outcomes after valve replacement than those with low-flow low-gradient severe aortic stenosis. Most studies (all observational) have shown that aortic valve replacement was associated with a survival benefit vs surveillance. Based on available data, the European Society of Cardiology/European Association for Cardio-Thoracic Surgery guidelines and European Association of Cardiovascular Imaging/American Society of Echocardiography suggest that these patients are more likely to have moderate aortic stenosis. This clinical entity is not mentioned in the American Heart Association/American College of Cardiology guidelines. Here we review the definition of NFLG severe aortic stenosis, potential diagnostic algorithms and points of error, the data supporting different management strategies, and the differing guidelines and outline the unanswered questions in the diagnosis and management of these challenging patients.

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.

Combined Value of Dimensionless Index and Transvalvular Flow Rate in Risk Stratification of Aortic Stenosis

Aortic stenosis (AS) is difficult to phenotype. The metrics of severity are frequently discordant, making prognostication challenging. Flow state is central to accurately determining severity. We sought to evaluate the prognostic value of dimensionless index (DI) and transvalvular flow rate (Q) in AS. We evaluated 2 independent, longitudinal registries of ≥ moderate severity AS (aortic valve area ≤1.5 cm2 or mean gradient ≥20 mm Hg) with complete data follow-up. In the primary cohort (n = 1,104, 77 ± 11 years, 40% female), the DI and Q category significantly predicted mortality (p <0.001) (Figure 1), with the highest risk being low DI and low Q (DI <0.25, Q ≤210 mL/s). In the validation cohort (n = 939, 70 ± 13 years, 42% female), similar results were seen in Kaplan-Meier (p <0.001) and multivariable Cox model analyses (p <0.01). We advocate for wider combined use of DI and Q in AS assessment to augment current diagnostic and prognostic approaches.

Prognostic value of flow-status in severe aortic stenosis patients undergoing percutaneous intervention

PURPOSE

Low-flow status is a mortality predictor in severe aortic stenosis (SAS) patients, including after transcatheter aortic valve implantation (TAVI) treatment. However, the best parameter to assess flow is unknown. Recent studies suggest that transaortic flow rate (FR) is superior to currently used stroke volume index (SVi) in defining low-flow states. Therefore, we aimed to evaluate the prognostic value of FR and SVi in patients undergoing TAVI.

METHODS

A single-centre retrospective analysis of all consecutive patients treated with TAVI for SAS between 2011 and 2019 was conducted. Low-FR was defined as < 200 mL/s and low-SVi as < 35 mL/m2. Primary endpoint was all-cause five-year mortality, analyzed using Kaplan-Meier curves and Cox regression models. Secondary endpoint was variation of NYHA functional class six months after procedure. Patients were further stratified according to ejection fraction (EF < 50%).

RESULTS

Of 489 cases, 59.5% were low-FR, and 43.1% low-SVi. Low-flow patients had superior surgical risk, worse renal function, and had a higher prevalence of coronary artery disease. Low-FR was associated with mortality (hazard ratio 1.36, p = 0.041), but not after adjustment to EuroSCORE II. Normal-SVi was not associated with survival, despite a significative p-trend for its continuous value. No associations were found for flow-status and NYHA recovery. When stratifying according to preserved and reduced EF, both FR and SVi did not predict all-cause mortality.

CONCLUSION

In patients with SAS undergoing TAVI, a low-FR state was associated with higher mortality, as well as SVi, but not at a 35 mL/m2 cut off.

Low Transvalvular Flow Rate in Patients Undergoing Transcatheter Aortic Valve Implantation (TAVI) Is a Predictor of Mortality: The TFR-TAVI Study

BACKGROUND

Transvalvular flow rate (TFR) represents a better reflection of transvalvular flow than the stroke volume index (SVi), and has recently emerged as a useful prognostic tool in patients undergoing surgical aortic valve replacement. There is a paucity of data investigating the role of TFR and its relationship with other clinical or echocardiographic factors in patients undergoing transcatheter aortic valve implantation (TAVI).

METHOD

This was a retrospective single-centre study of 629 consecutive patients who underwent TAVI between March 2009 and September 2020. Pre-TAVI low TFR was defined as <200 c/s. The primary study end point was all-cause mortality.

RESULTS

Low TFR was observed in 41.8% (263/629) of included patients and was associated with increasing age, low body surface area, hypertension, diabetes, atrial fibrillation, left ventricular (LV) dysfunction, and significant mitral regurgitation. LV function status and severity of aortic valve disease were independent predictors of low TFR. Low TFR was significantly associated with long-term all-cause mortality even after adjustment for other risk factors (adjusted hazard ratio [aHR] 1.44; 95% confidence interval [CI] 1.02-2.03; p=0.038). When data were stratified according to SVi, low TFR was an independent predictor of long-term all-cause mortality in patients with normal SVi (aHR 1.98; 95% CI 1.06-3.69; p=0.032) but not in patients with low SVi (HR 1.23; 95% CI 0.71-2.11; p=0.46; p=0.016 for interaction).

CONCLUSIONS

Low TFR is common in patients undergoing TAVI and is an independent predictor of all-cause mortality, particularly in patients with normal SVi.

Multimodality assessment of high- vs. low-gradient aortic stenosis using echocardiography and cardiac CT

BACKGROUND

Aortic valve area (AVA) using CT-LVOT area (AVACT-LVOT) <1.2 ​cm2 has been shown comparable to echocardiography AVA of <1.0 ​cm2 for severe aortic stenosis (AS). Current study evaluates how AS diagnosis will be affected when we substitute CT-LVOT with echo derived LVOT.

METHODS

We retrospectively studied 367 patients who underwent cardiac CTA and echocardiogram for assessment of high- and low-gradient AS (HG-AS and LG-AS). AVACT-LVOT was derived from CT-LVOT area and echo doppler data. Three AVACT-LVOT categories were created (<1.0, 1.0-1.2 and ​> ​1.2 ​cm2). Outcomes were defined as composite of all-cause mortality and/or valve intervention.

RESULTS

Median echocardiographic profiles were consistent with severe AS across three AVACT-LVOT categories for HG-AS. HG-AS patients with AVACT-LVOT >1.2 ​cm2 had larger median CT-LVOT area (5.06 ​cm2) and AVC (2917AU). Among LG-AS with AVACT-LVOT ​≤1.2 cm2, 57% met echo criteria for low-flow LG-AS and 63% met criteria for severe AS using aortic valve calcium (AVC). Additionally, 45% with AVACT-LVOT >1.2 ​cm2 had larger median CT-LVOT area (5.43 ​cm2) and AVC (2389AU). Patients with AVACT-LVOT >1.2 ​cm2 and high AVC had large body surface area and were mostly characterized as severe with indexed AVA and AVC. Stroke volume index using CT-LVOT reclassified 70% of low-flow, LG-AS as normal flow, LG-AS. Composite outcomes were higher among patients with AVACT-LVOT ≤1.2 ​cm2 (p ​< ​0.01), however, with no superior net reclassification improvement compared to AVAecho <1.0 ​cm2.

CONCLUSION

AVACT-LVOT ≤1.2 ​cm2 is a reasonable CT criterion for severe AS. Large LVOT with elevated AVC identified a severe AS phenotype despite an AVACT-LVOT >1.2 ​cm2, best characterized by indexed AVA and AVC.

Performance of Computed Tomographic Angiography-Based Aortic Valve Area for Assessment of Aortic Stenosis

Background A total of 40% of patients with severe aortic stenosis (AS) have low-gradient AS, raising uncertainty about AS severity. Aortic valve calcification, measured by computed tomography (CT), is guideline-endorsed to aid in such cases. The performance of different CT-derived aortic valve areas (AVAs) is less well studied. Methods and Results Consecutive adult patients with presumed moderate and severe AS based on echocardiography (AVA measured by continuity equation on echocardiography <1.5 cm2) who underwent cardiac CT were identified retrospectively. AVAs, measured by direct planimetry on CT (AVACT) and by a hybrid approach (AVA measured in a hybrid manner with echocardiography and CT [AVAHybrid]), were measured. Sex-specific aortic valve calcification thresholds (≥1200 Agatston units in women and ≥2000 Agatston units in men) were applied to adjudicate severe or nonsevere AS. A total of 215 patients (38.0% women; mean±SD age, 78±8 years) were included: normal flow, 59.5%; and low flow, 40.5%. Among the different thresholds for AVACT and AVAHybrid, diagnostic performance was the best for AVACT <1.2 cm2 (sensitivity, 85%; specificity, 26%; and accuracy, 72%), with no significant difference by flow status. The percentage of patients with correctly classified AS severity (correctly classified severe AS+correctly classified moderate AS) was as follows; AVA measured by continuity equation on echocardiography <1.0 cm2, 77%; AVACT <1.2 cm2, 73%; AVACT <1.0 cm2, 58%; AVAHybrid <1.2 cm2, 59%; and AVAHybrid <1.0 cm2, 45%. AVACT cut points of 1.52 cm2 for normal flow and 1.56 cm2 for low flow, provided 95% specificity for excluding severe AS. Conclusions CT-derived AVAs have poor discrimination for AS severity. Using an AVACT <1.2-cm2 threshold to define severe AS can produce significant error. Larger AVACT thresholds improve specificity.

Aortic Valve Disease, Transcatheter Aortic Valve Replacement, and the Heart Failure Patient: A State-of-the-Art Review

Concomitant aortic stenosis (AS) in heart failure (HF) is associated with high rates of mortality and morbidity. Current guidelines recommend aortic valve replacement in patients with severe symptomatic AS and asymptomatic AS with left ventricular ejection fraction <50% and during other cardiac surgeries. Transcatheter aortic valve replacement (TAVR) has now allowed for the treatment of severe AS in previously inoperable or high-surgical-risk patients. Leveraging multimodality imaging techniques is increasingly recognized for reinforcing the rationale for intervening early, thus mitigating the risk of ongoing progression to advanced HF. There are increasing data in favor of TAVR in diverse clinical scenarios, particularly asymptomatic AS and moderate AS. Limited information is, however, available regarding the advantages of HF medical therapy before and after intervention. This review aims to comprehensively examine the phenotypes of AS in the context of HF progression, while exploring the evolving role of TAVR in specific populations.

Role of Multimodal Cardiac Imaging in Low-Flow, Low-Gradient Aortic Stenosis

•Approximately two-thirds of patients with PLF-LG AS have severe aortic stenosis. •Multimodal evaluation is recommended in the group of patients with PLF-LG AS. •Patients with PLF-LG-AS should be screened for cardiac amyloidosis.

Machine learning prediction of progressive subclinical myocardial dysfunction in moderate aortic stenosis

Background

Moderate severity aortic stenosis (AS) is poorly understood, is associated with subclinical myocardial dysfunction, and can lead to adverse outcome rates that are comparable to severe AS. Factors associated with progressive myocardial dysfunction in moderate AS are not well described. Artificial neural networks (ANNs) can identify patterns, inform clinical risk, and identify features of importance in clinical datasets.

Methods

We conducted ANN analyses on longitudinal echocardiographic data collected from 66 individuals with moderate AS who underwent serial echocardiography at our institution. Image phenotyping involved left ventricular global longitudinal strain (GLS) and valve stenosis severity (including energetics) analysis. ANNs were constructed using two multilayer perceptron models. The first model was developed to predict change in GLS from baseline echocardiography alone and the second to predict change in GLS using data from baseline and serial echocardiography. ANNs used a single hidden layer architecture and a 70%:30% training/testing split.

Results

Over a median follow-up interval of 1.3 years, change in GLS (≤ or >median change) could be predicted with accuracy rates of 95% in training and 93% in testing using ANN with inputs from baseline echocardiogram data alone (AUC: 0.997). The four most important predictive baseline features (reported as normalized % importance relative to most important feature) were peak gradient (100%), energy loss (93%), GLS (80%), and DI < 0.25 (50%). When a further model was run including inputs from both baseline and serial echocardiography (AUC 0.844), the top four features of importance were change in dimensionless index between index and follow-up studies (100%), baseline peak gradient (79%), baseline energy loss (72%), and baseline GLS (63%).

Conclusions

Artificial neural networks can predict progressive subclinical myocardial dysfunction with high accuracy in moderate AS and identify features of importance. Key features associated with classifying progression in subclinical myocardial dysfunction included peak gradient, dimensionless index, GLS, and hydraulic load (energy loss), suggesting that these features should be closely evaluated and monitored in AS.

Transcatheter Aortic Valve Replacement Prognostication with Augmented Mean Arterial Pressure

BACKGROUND

Post-transcatheter aortic valve replacement (TAVR) patient outcome is an important research topic. To accurately assess post-TAVR mortality, we examined a family of new echo parameters (augmented systolic blood pressure (AugSBP) and arterial mean pressure (AugMAP)) derived from blood pressure and aortic valve gradients.

METHODS

Patients in the Mayo Clinic National Cardiovascular Diseases Registry-TAVR database who underwent TAVR between 1 January 2012 and 30 June 2017 were identified to retrieve baseline clinical, echocardiographic and mortality data. AugSBP, AugMAP and valvulo-arterial impedance (Zva) (Zva) were evaluated using Cox regression. Receiver operating characteristic curve analysis and the c-index were used to assess the model performance against the Society of Thoracic Surgeons (STS) risk score.

RESULTS

The final cohort contained 974 patients with a mean age of 81.4 ± 8.3 years old, and 56.6% were male. The mean STS risk score was 8.2 ± 5.2. The median follow-up duration was 354 days, and the one-year all-cause mortality rate was 14.2%. Both univariate and multivariate Cox regression showed that AugSBP and AugMAP parameters were independent predictors for intermediate-term post-TAVR mortality (all p < 0.0001). AugMAP1 < 102.5 mmHg was associated with a 3-fold-increased risk of all-cause mortality 1-year post-TAVR (hazard ratio 3.0, 95%confidence interval 2.0-4.5, p < 0.0001). A univariate model of AugMAP1 surpassed the STS score model in predicting intermediate-term post-TAVR mortality (area under the curve: 0.700 vs. 0.587, p = 0.005; c-index: 0.681 vs. 0.585, p = 0.001).

CONCLUSIONS

Augmented mean arterial pressure provides clinicians with a simple but effective approach to quickly identify patients at risk and potentially improve post-TAVR prognosis.

Valvular Heart Disease: New Concepts in Pathophysiology and Therapeutic Approaches

This review discusses recent advancements in the field of valvular heart disease. Topics covered include recognition of the impact of atrial fibrillation on development and assessment of valvular disease, strategies for global prevention of rheumatic heart disease, understanding and management of secondary mitral regurgitation, the updated classification of bicuspid aortic valve disease, recognition of heightened cardiovascular risk associated with moderate aortic stenosis, and a growing armamentarium of transcatheter therapies.

Mixed aortic stenosis and regurgitation: a clinical conundrum

Mixed aortic stenosis (AS) and aortic regurgitation (AR) is the most frequent concomitant valve disease worldwide and represents a heterogeneous population ranging from mild AS with severe AR to mild AR with severe AS. About 6.8% of patients with at least moderate AS will also have moderate or greater AR, and 17.9% of patients with at least moderate AR will suffer from moderate or greater AS. Interest in mixed AS/AR has increased, with studies demonstrating that patients with moderate mixed AS/AR have similar outcomes to those with isolated severe AS. The diagnosis and quantification of mixed AS/AR severity are predominantly echocardiography-based, but the combined lesions lead to significant limitations in the assessment. Aortic valve peak velocity is the best parameter to evaluate the combined haemodynamic impact of both lesions, with a peak velocity greater than 4.0 m/s suggesting severe mixed AS/AR. Moreover, symptoms, increased left ventricular wall thickness and filling pressures, and abnormal left ventricular global longitudinal strain likely identify high-risk patients who may benefit from closer follow-up. Although guidelines recommend interventions based on the predominant lesion, some patients could potentially benefit from earlier intervention. Once a patient is deemed to require intervention, for patients receiving transcatheter valves, the presence of mixed AS/AR could confer benefit to those at high risk of paravalvular leak. Overall, the current approach of managing patients based on the dominant lesion might be too reductionist and a more holistic approach including biomarkers and multimodality imaging cardiac remodelling and inflammation data might be more appropriate.

TAVI for patients with normal-flow low-gradient compared to high-gradient aortic stenosis

BACKGROUND

Normal-flow (stroke volume index, SVi >35 ml/m²) low-gradient (dPmean <40 mmHg) aortic stenosis (NFLG-AS) is subject of scientific debate. Guidelines fail to give conclusive treatment recommendations. We hypothesized that NFLG patients are heterogenous, containing a subgroup similar to high-gradient aortic stenosis patients (dPmean ≥40 mmHg, HG-AS) concerning characteristics and outcomes.

METHODS

2326 patients undergoing transcatheter aortic valve replacement (TAVI) at our centre between 2013 and 2019 were analysed. 386 patients fulfilled criteria of NFLG-AS. Their median dPmean was 33 mmHg, which was used for grouping (204 patients with higher gradient NFLG-AS, 186 patients with lower gradient NFLG-AS). They were compared to 956 HG-AS patients.

RESULTS

Characteristics of lower gradient NFLG-AS patients differed from HG-AS patients in many aspects while higher gradient NFLG-AS and HG-AS patients were mostly similar, underscored by higher Society of Thoracic Surgeons scores in lower gradient NFLG-AS (lower gradient NFLG-AS, 3.9, HG-AS, 3.0, p = 0.03, higher gradient NFLG-AS, 3.0, p = 0.04). Procedural complications were comparable. Estimated 3-year all-cause mortality was higher in lower gradient NFLG-AS compared to HG-AS patients (hazard ratio 1.7, p < 0.01), whereas mortality of higher gradient NFLG-AS was similar to HG-AS patients (hazard ratio 1.2, p = 0.31). Cardiovascular mortality was highest among lower gradient NFLG-AS patients (21.6% vs. higher gradient NFLG-AS, 15.4%, vs. HG-AS, 11.1%, p < 0.01).

CONCLUSIONS

NFLG-AS patients are indeed heterogenous. NFLG-AS patients with higher gradients resemble HG-AS patients in clinical characteristics and outcomes and should not be treated differently. Lower gradient NFLG-AS patients have increased long-term mortality and the use of TAVI requires careful consideration.

Underestimation of Aortic Stenosis Severity by Doppler Mean Gradient during Atrial Fibrillation: Insights from Aortic Valve Weight

BACKGROUND

Doppler mean gradient (MG) can underestimate aortic stenosis (AS) severity when obtained during atrial fibrillation (AF) compared with sinus rhythm (SR). Aortic valve weight (AVW) is a flow-independent measure of AS severity. The objective of this study was to determine whether AVW or AVW/MG ratio was increased in AF versus SR in patients with AS.

METHODS

Excised native aortic valves from 495 consecutive patients (median age, 77 years; interquartile range [IQR], 71-82 years; 40% women), with left ventricular ejection fractions ≥50% who underwent surgical aortic valve replacement for native valve severe AS (aortic valve area ≤ 1 cm² or indexed aortic valve area ≤ 0.6 cm²/m²) were weighed. Excised AVW/MG ratios were compared in AF versus SR in patients with high-gradient AS (aortic peak velocity ≥ 4 m/sec or MG ≥ 40 mm Hg) and low-gradient AS (aortic peak velocity < 4 m/sec and MG < 40 mm Hg) in sex-specific analyses.

RESULTS

AF was present in 51 patients (10%; 11 of 51 [22%] had low-gradient AS) and SR in 444 (90%; 23 of 444 [5%] had low-gradient AS). There was no difference in sex distribution between AF and SR. Aortic valve area was not different, but forward stroke volume index and transaortic valve flow rate were lower in AF (P ≤ .002 for all); MG was lower in AF versus SR (median, 46 mm Hg [IQR, 37-50 mm Hg] vs 50 mm Hg [IQR, 44-61 mm Hg]; P < .0001). Overall AVW was not different (median, 2,290 mg [IQR, 1,830-3,063 mg] vs 2,140 mg [IQR, 1,530-2,958 mg]; P = .31), but overall AVW/MG ratio was higher in AF (median, 55 [IQR, 41-67] vs 42 [IQR, 30-55]; P = .001). In sex- and MG-specific analyses, the AVW/MG ratio was higher in AF compared with SR in men with high-gradient AS (median, 58 [IQR, 41-75] vs 51 [IQR, 39-61]; P = .03), but the differences were not statistically significant between AF and SR in other groups.

CONCLUSIONS

AVW was discordant to Doppler MG in AF compared with SR in men with high-gradient AS. Additional studies of the relationship of MG to other measures of AS severity, such as leaflet fibrosis, are needed.

Risk for Mortality with Increasingly Severe Aortic Stenosis: An International Cohort Study

BACKGROUND

Aortic stenosis (AS) is the most common valvular heart disease in high-income countries. Adjusted for clinical confounders, the risk associated with increasing AS severity across the spectrum of AS severity remains uncertain.

METHODS

The authors conducted an international, multicenter, parallel-cohort study of 217,599 Australian (mean age, 76.0 ± 7.3 years; 49.3% women) and 30,865 US (mean age, 77.4 ± 7.3 years; 52.2% women) patients aged ≥65 years who underwent echocardiography. Patients with previous aortic valve replacement were excluded. The risk of increasing AS severity, quantified by peak aortic velocity (Vmax), was assessed through linkage to 97,576 and 14,481 all-cause deaths in Australia and the United States, respectively.

RESULTS

The distribution of AS severity (mean Vmax, 1.7 ± 0.7 m/sec) was similar in both cohorts. Compared with those with Vmax of 1.0 to 1.49 m/sec, those with Vmax of 2.50 to 2.99 m/sec (US cohort) or Vmax of 3.0 to 3.49 m/sec (Australian cohort) had a 1.5-fold increase in mortality risk within 10 years, adjusting for age, sex, presence of left heart disease, and left ventricular ejection fraction. Overall, the adjusted risk for mortality plateaued (1.75- to 2.25-fold increased risk) above a Vmax of 3.5 m/sec. This pattern of mortality persisted despite adjustment for a comprehensive list of comorbidities and treatments within the US cohort.

CONCLUSIONS

Within large, parallel patient cohorts managed in different health systems, similar patterns of mortality linked to increasingly severe AS were observed. These findings support ongoing clinical trials of aortic valve replacement in patients with nonsevere AS and suggest the need to develop and apply more proactive surveillance strategies in this high-risk population.

Integrating hemodynamics with ventricular and valvular remodeling in aortic stenosis. A paradigm shift in therapeutic decision making

Aortic valve stenosis (AS) has traditionally been approached in hemodynamic terms. Although hemodynamics and symptoms have formed the basis of recommending interventional treatment in AS, other factors reflecting left ventricular and valvular and/or vascular remodeling are equally important for the prognosis and outcome of patients with AS. Left ventricular and valvular/vascular remodeling in AS do not consistently correlate with hemodynamic severity of AS. Those remodeling changes are reflected and can be detected by a variety of novel laboratory and imaging techniques, including biomarkers, echocardiography, cardiac magnetic resonance and gated Computer Tomography (CT) imaging. Taking all those elements into Heart Team therapeutic decision making in patients with AS, can significantly improve appropriate patient selection for interventional treatment and patient outcomes. We review this novel approach and propose a simple algorithm for decision making by the Heart Team, in patients with moderate or severe AS.

Impact of Sex on Mortality in Patients Undergoing Surgical Aortic Valve Replacement

Aortic stenosis (AS) is the second most common valvular heart disease in the United States. Although the prevalence of AS does not significantly differ between the sexes, there is some controversy on whether sex differences affect the long-term mortality of patients with severe AS undergoing surgical aortic valve replacement (SAVR). Therefore, we retrospectively analyzed the medical records of 917 patients (female, n = 424 [46.2%]) with severe AS who had undergone isolated SAVR at a tertiary care center between January 2005 and December 2018. During a median follow-up of 5.2 years, 74 (15.0%) male patients and 41 (9.7%) female patients died. The Kaplan–Meier analysis revealed that the 10-year mortality rate was significantly higher in male than female patients (24.7% vs. 17.9%, log-rank p = 0.005). In the sequential Cox proportional hazard regression model for assessing long-term mortality up to 10 years post-surgery, the adjusted hazard ratio of male sex for mortality was 1.93 (95% confidence interval, 1.28–2.91; p = 0.002). The association between male sex and postoperative long-term mortality was not significantly diminished by any demographic or clinical factor in subgroup analyses. In conclusion, female sex was significantly associated with better long-term survival in patients with severe AS undergoing SAVR.

Increasing risk of mortality across the spectrum of aortic stenosis is independent of comorbidity & treatment: An international, parallel cohort study of 248,464 patients

Background

While large scientific and medical evidence has demonstrated the increased risk of death and cardiovascular mortality in patients with severe AS, the independent contribution of moderate AS to an increased risk of death remains uncertain.

Methods and findings

We conducted a multicenter study including a cohort of 30,865 US patients and another cohort of 217,599 Australian patients with equivalent echocardiographic and aortic valve profiling over the same period (2003–2017). During a median 5.2 years (US) and 4.4 years (Australian) follow-up, the risk of death (hazard ratio) of patients with moderate AS as compared to those without AS was 1.66 (95%CI 1.52–1.80) and 1.37 (95%CI 1.34–1.41) in the US and Australian cohorts, even after adjusting this analysis for age and sex. This increased risk of death and cardiovascular mortality (odds ratio) in patients with moderate AS was consistent also across subgroups of left ventricular ejection fraction (LVEF) (subgroups of LVEF < 40%, 40–49%, 50–59%, and ≥ 60%: OR of moderate AS for CV mortality 2.0 [95%CI 1.4–2.7], 1.7 [95%CI 1.2–2.4], 1.5 [95%CI 1.1–1.9], and 1.4 [95%CI 1.2–1.6], respectively).

Conclusions

The findings of this study suggest that patients with moderate AS have a potential increased risk of death and cardiovascular mortality, regardless of age, sex, and LVEF. Hence, these data suggest the need to develop specific strategies to detect and treat individuals with moderate AS.

Preprocedural Prognostic Factors in Acute Decompensated Aortic Stenosis

Acute decompensated aortic stenosis (ADAS) is common and associated with poor outcomes. Myocardial remodeling and function, including a novel echo staging classification (0 to 4, representing increasing degrees of cardiac damage/dysfunction), impact outcomes in stable aortic stenosis. However, this has not been assessed in patients with ADAS. This study aims to evaluate the impact of the myocardium, echo staging classification, and clinical parameters on mortality in ADAS. ADAS was defined as an acute deterioration in symptoms (New York Heart Association 4, Canadian Cardiovascular Society 3/4, or syncope) that warranted admission to the hospital and urgent aortic valve replacement. Using a retrospective observational study design, 292 consecutive patients with ADAS who underwent transcatheter aortic valve implantation (TAVI) were identified and included in this study. Echocardiographic and clinical characteristics were evaluated using regression analysis. The outcome was all-cause mortality after TAVI. At 1 year after TAVI, advanced echo staging (>2) independently predicted mortality (hazards ratio: 1.85, 95% confidence interval: 1.01 to 3.39; p = 0.045). At a follow-up of 2.4 ± 1.4 years, myocardial, valvular, and clinical parameters did not predict mortality, except for frailty (hazards ratio: 2.31, 95% confidence interval: 1.38 to 3.85; p = 0.001). In patients with ADAS, short-term mortality after TAVI is influenced by more advanced cardiac damage/dysfunction based on the echo staging classification, whereas mid-term mortality is driven by frailty rather than echo staging classification.

Predicting outcomes in patients with aortic stenosis using machine learning: the Aortic Stenosis Risk (ASteRisk) score

Objective

To use echocardiographic and clinical features to develop an explainable clinical risk prediction model in patients with aortic stenosis (AS), including those with low-gradient AS (LGAS), using machine learning (ML).

Methods

In 1130 patients with moderate or severe AS, we used bootstrap lasso regression (BLR), an ML method, to identify echocardiographic and clinical features important for predicting the combined outcome of all-cause mortality or aortic valve replacement (AVR) within 5 years after the initial echocardiogram. A separate hold out set, from a different centre (n=540), was used to test the generality of the model. We also evaluated model performance with respect to each outcome separately and in different subgroups, including patients with LGAS.

Results

Out of 69 available variables, 26 features were identified as predictive by BLR and expert knowledge was used to further reduce this set to 9 easily available and input features without loss of efficacy. A ridge logistic regression model constructed using these features had an area under the receiver operating characteristic curve (AUC) of 0.74 for the combined outcome of mortality/AVR. The model reliably identified patients at high risk of death in years 2–5 (HRs ≥2.0, upper vs other quartiles, for years 2–5, p<0.05, p=not significant in year 1) and was also predictive in the cohort with LGAS (n=383, HRs≥3.3, p<0.05). The model performed similarly well in the independent hold out set (AUC 0.78, HR ≥2.5 in years 1–5, p<0.05).

Conclusion

In two separate longitudinal databases, ML identified prognostic features and produced an algorithm that predicts outcome for up to 5 years of follow-up in patients with AS, including patients with LGAS. Our algorithm, the Aortic Stenosis Risk (ASteRisk) score, is available online for public use.

A Preliminary Study on the Usage of a Data-Driven Probabilistic Approach to Predict Valve Performance Under Different Physiological Conditions

Predicting potential complications after aortic valve replacement (AVR) is a crucial task that would help pre-planning procedures. The goal of this work is to generate data-driven models based on logistic regression, where the probability of developing transvalvular pressure gradient (DP) that exceeds 20 mmHg under different physiological conditions can be estimated without running extensive experimental or computational methods. The hemodynamic assessment of a 26 mm SAPIEN 3 transcatheter aortic valve and a 25 mm Magna Ease surgical aortic valve was performed under pulsatile conditions of a large range of systolic blood pressures (SBP; 100-180 mmHg), diastolic blood pressures (DBP; 40-100 mmHg), and heart rates of 60, 90 and 120 bpm. Logistic regression modeling was used to generate a predictive model for the probability of having a DP > 20 mmHg for both valves under different conditions. Experiments on different pressure conditions were conducted to compare the probabilities of the generated model and those obtained experimentally. To test the accuracy of the predictive model, the receiver operation characteristics curves were generated, and the areas under the curve (AUC) were calculated. The probabilistic predictive model of DP > 20 mmHg was generated with parameters specific to each valve. The AUC obtained for the SAPIEN 3 DP model was 0.9465 and that for Magna Ease was 0.9054 indicating a high model accuracy. Agreement between the DP probabilities obtained between experiments and predictive model was found. This model is a first step towards developing a larger statistical and data-driven model that can inform on certain valves reliability during AVR pre-procedural planning.

Value of Left Ventricular Indexed Ejection Time to Characterize the Severity of Aortic Stenosis

Aims: The assessment of aortic stenosis (AS) severity is still challenging, especially in abnormal hemodynamic conditions. Left ventricular ejection time (LVET) has been historically related to AS severity, but it also depends on heart rate (HR) and systolic function. Our aim was to verify if correcting LVET (LVET index, LVETI) by its determinants is helpful for the assessment of AS severity, irrespective of hemodynamic conditions. Methods and results: We retrospectively studied 152 patients with AS and 378 patients with heart failure and no-AS. At multivariate analysis, LVET (assessed with pulsed-wave Doppler) showed a strong correlation with stroke volume index (SVI) (Beta 0.354; p < 0.001), HR (−0.385; p < 0.001), AS grade (Beta 0.301; p < 0.001) and, less significantly, ejection fraction (LVEF) (Beta 0.108; p = 0.001). AS grade was confirmed to be a major determinant of LVET, irrespective of forward flow (assessed by SVI and transvalvular flow rate) and LVEF (above and below 50%). A regression equation was derived to index LVET (LVETI) to HR and SVI. By using this formula, LVETI detected severe AS more accurately (AUC 0.812, p < 0.001) than LVET alone (AUC 0.755, p for difference = 0.005). Similar results were observed in patients with abnormal flow status. As an exploratory finding, we observed that the highest tertile of LVETI was associated with a higher rate of aortic valve interventions during follow-up. Conclusions: LVETI correlates with AS severity better than uncorrected LVET, independently from hemodynamic conditions, and may help to discriminate severe AS. This finding needs confirmation in larger prospective multicenter studies.

Aortic Stenosis: New Insights in Diagnosis, Treatment, and Prevention

There has been an explosion of diagnostic, prognostic, and treatment data in aortic stenosis (AS). Severity of AS should be based not only on valve hemodynamics, but underlying LV dysfunction and comorbidities. Indications for aortic valve replacement continue to evolve, extending to patients with less than severe AS. There are several trials to find a medical therapy to reduce the progression of AS. An application of artificial intelligence and clinical trial results will have a major impact in identifying asymptomatic patients and optimal treatment to the right patient at the right time.

Aortic stenosis (AS) is one of the most common valvular heart diseases and the number of patients with AS is expected to increase globally as the older population is growing fast. Since the majority of patients are elderly, AS is no longer a simple valvular heart disease of left ventricular outflow obstruction but is accompanied by other cardiac and comorbid conditions. Because of the significant variations of the disease, identifying patients at high risk and even earlier detection of patients with AS before developing symptomatic severe AS is becoming increasingly important. With the proven of efficacy and safety of transcatheter aortic valve replacement (TAVR) in the severe AS population, there is a growing interest in applying TAVR in those with less than severe AS. A medical therapy to reduce or prevent the progression in AS is actively investigated by several randomized control trials. In this review, we will summarize the most recent findings in AS and discuss potential future management strategies of patients with AS.

Relationship Between the Ratio of Acceleration Time/Ejection Time and Mortality in Patients With High-Gradient Severe Aortic Stenosis

Background

The ratio of acceleration time/ejection time (AT/ET) is a simple and reproducible echocardiographic parameter that integrates aortic stenosis severity and its consequences on the left ventricle. No study has specifically assessed the prognostic impact of AT/ET on outcome in patients with high‐gradient severe aortic stenosis (SAS) and no or mild symptoms. We sought to evaluate the relationship between AT/ET and mortality and determine the best predictive AT/ET cutoff value in these patients.

Methods and Results

A total of 353 patients (median age, 79 years; 46% women) with high‐gradient (mean pressure gradient ≥40 mm Hg and/or aortic peak jet velocity ≥4 m/s) SAS, left ventricular ejection fraction ≥50%, and no or mild symptoms were studied. The impact of AT/ET ≤0.35 or >0.35 on all‐cause mortality was retrospectively studied. During a median follow‐up of 39 (25th–75th percentile, 23–62) months, 70 patients died. AT/ET >0.35 was associated with a considerable increased mortality risk after adjustment for established prognostic factors in SAS under medical and/or surgical management (adjusted hazard ratio [HR], 2.54; 95% CI, 1.47–4.37; P<0.001) or conservative management (adjusted HR, 3.29; 95% CI, 1.70–6.39; P<0.001). Moreover, AT/ET >0.35 improved the predictive performance of models including established risk factors in SAS with better global model fit, reclassification, and discrimination. After propensity matching, increased mortality risk persisted when AT/ET >0.35 (adjusted HR, 2.10; 95% CI, 1.12–3.90; P<0.001).

Conclusions

AT/ET >0.35 is a strong predictor of outcome in patients with SAS and no or only mild symptoms and identifies a subgroup of patients at higher risk of death who may derive benefit from earlier aortic valve replacement.

Severe aortic stenosis echocardiographic thresholds revisited

BACKGROUND

In view of inconsistencies in threshold values of severe aortic stenosis (AS) hemodynamic indices, it is unclear what is the relative contribution of each variable in a binary classification of AS based on aortic valve replacement (AVR) indication. We aimed to assess relative discriminative value and optimal threshold of each constituent hemodynamic parameter for this classification and confirm additional prognostic value.

METHODS

Echocardiography studies of 168 patients with ≥ moderate AS were included. AS types were dichotomized into Group-A, comprising moderate and Normal-Flow Low-Gradient (NFLG), and Group-B, comprising High-Gradient(HG), Low Ejection Fraction Low-Flow Low-Gradient(Low EF-LFLG), and Paradoxical Low-Flow Low-Gradient(PLFLG) AS. Aortic valve area (AVA), Doppler velocity index (DVI), peak aortic velocity, mean gradient, stroke volume index and transaortic flow rate(TFR) were assessed for A/B Group discrimination value and optimal thresholds were determined. Dichotomized values were assessed for predictive value for AVR or death.

RESULTS

C-statistic values for binary AS classification was .74-.9 for the tested variables. AVA and DVI featured the highest score, and SVI the lowest one. AVA≤.81 cm² and DVI≤.249 had 87.6% and 86% respective sensitivity for Group B patients, and a similar specificity of 80.9%. During a mean follow-up of 9.1±10.1 months, each of the tested dichotomized variables except for SVI predicted AVR or death on multivariate analysis.

CONCLUSION

An AVA value ≤.81 cm² or a DVI ≤ .249 threshold carry the highest discriminative value for severe AS in patients with aortic stenosis, translating into an independent prognostic value, and can be helpful in making clinical decisions.

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.

The impact of shape uncertainty on aortic-valve pressure-drop computations

Patient-specific image-based computational fluid dynamics (CFD) is widely adopted in the cardiovascular research community to study hemodynamics, and will become increasingly important for personalized medicine. However, segmentation of the flow domain is not exact and geometric uncertainty can be expected which propagates through the computational model, leading to uncertainty in model output. Seventy-four aortic-valves were segmented from computed tomography images at peak systole. Statistical shape modeling was used to obtain an approximate parameterization of the original segmentations. This parameterization was used to train a meta-model that related the first five shape mode coefficients and flowrate to the CFD-computed transvalvular pressure-drop. Consequently, shape uncertainty in the order of 0.5 and 1.0 mm was emulated by introducing uncertainty in the shape mode coefficients. A global variance-based sensitivity analysis was performed to quantify output uncertainty and to determine relative importance of the shape modes. The first shape mode captured the opening/closing behavior of the valve and uncertainty in this mode coefficient accounted for more than 90% of the output variance. However, sensitivity to shape uncertainty is patient-specific, and the relative importance of the fourth shape mode coefficient tended to increase with increases in valvular area. These results show that geometric uncertainty in the order of image voxel size may lead to substantial uncertainty in CFD-computed transvalvular pressure-drops. Moreover, this illustrates that it is essential to assess the impact of geometric uncertainty on model output, and that this should be thoroughly quantified for applications that wish to use image-based CFD models.

Doppler Mean Gradient Is Discordant to Aortic Valve Calcium Scores in Patients with Atrial Fibrillation Undergoing Transcatheter Aortic Valve Replacement

BACKGROUND

Doppler mean gradient (MG) may underestimate aortic stenosis (AS) severity when obtained during atrial fibrillation (AF) because of lower forward flow compared with sinus rhythm (SR). Whether AS is more advanced at the time of referral for aortic valve intervention in AF compared with SR is unknown. The aim of this study was to examine flow-independent computed tomographic aortic valve calcium scores (AVCS) and their concordance to MG in AF versus SR in patients undergoing transcatheter aortic valve replacement (TAVR).

METHODS

Patients who underwent TAVR from 2016 to 2020 for native valve severe AS with left ventricular ejection fraction ≥ 50% were identified from an institutional TAVR database. MGs during AF and SR in high-gradient AS (HGAS) and low-gradient AS (LGAS) were compared with AVCS (AVCS/MG ratio). AVCS were obtained within 90 days of pre-TAVR echocardiography.

RESULTS

Six hundred thirty-three patients were included; median age was 82 years (interquartile range [IQR], 76-86 years), and 46% were women. AF was present in 109 (17%) and SR in 524 (83%) patients during echocardiography. Aortic valve area index was slightly smaller in AF versus SR (0.43 cm²/m² [IQR, 0.39-0.47 cm²/m²] vs 0.46 cm²/m² [IQR, 0.41-0.51 cm²/m²], P = .0003). Stroke volume index, transaortic flow rate, and MG were lower in AF (P < .0001 for all). AVCS were higher in men with AF compared with SR (3,510 Agatston units [AU] [IQR, 2,803-4,030 AU] vs 2,722 AU [IQR, 2,180-3,467 AU], P < .0001) in HGAS but not in LGAS. AVCS were not different in women with AF versus SR. Overall AVCS/MG ratios were higher in AF versus SR in HGAS and LGAS (P < .03 for all), except in women with LGAS.

CONCLUSIONS

AVCS were higher than expected by MG in AF compared with SR. The very high AVCS in men with AF and HGAS at the time of TAVR suggests late diagnosis of severe AS because of underestimated AS severity during progressive AS and/or late referral to TAVR. Additional studies are needed to examine the extent to which echocardiography may be underestimating AS severity in AF.

Myocardial Contraction Fraction for Risk Stratification in Low-Gradient Aortic Stenosis With Preserved Ejection Fraction

BACKGROUND

Myocardial contraction fraction (MCF) is a volumetric measure of myocardial shortening independent of left ventricular size and geometry. This multicenter study investigates the usefulness of MCF for risk stratification in low-gradient severe aortic stenosis with preserved ejection fraction.

METHODS

We included 643 consecutive patients with low-gradient severe aortic stenosis with preserved ejection fraction in whom MCF was computed at baseline and analyzed mortality during follow-up.

RESULTS

Throughout follow-up with medical and surgical management (34.9 [16.1-65.3] months), lower MCF tertiles had higher mortality than the highest tertile. Eighty-month survival was 56±4% for MCF>41%, 41±4% for MCF 30% to 41%, and 40±4% for MCF<30% (P<0.001). After comprehensive adjustment, mortality risk remained high for MCF 30% to 41% (adjusted hazard ratio, 1.53 [1.08-2.18]) and for MCF<30% (adjusted hazard ratio, 1.82 [1.24-2.66]) versus MCF>41%. The optimal MCF cutoff point for mortality prediction was 41%. Age, body mass index, Charlson index, peak aortic velocity, and ejection fraction were independently associated with mortality. MCF (χ² to improve 10.39; P=0.001), provided greater additional prognostic value over the baseline parameters than stroke volume (SV) index (χ² to improve 5.41; P=0.042), left ventricular mass index (χ² to improve 2.15; P=0.137), or global longitudinal strain (χ² to improve 3.67; P=0.061). MCF outperformed ejection fraction for mortality prediction. When patients were classified by SV index and MCF, mortality risk was low when SV index was ≥30 mL/m² and MCF>41%, higher for patients with SV index ≥30 mL/m² and MCF≤41% (adjusted hazard ratio, 1.47 [1.05-2.07]) and extremely high for patients with SV index <30 mL/m² (adjusted hazard ratio, 2.29 [1.45-3.62]).

CONCLUSIONS

MCF is a valuable marker of risk in low-gradient severe aortic stenosis with preserved ejection fraction and could improve decision-making, especially in normal-flow low-gradient severe aortic stenosis with preserved ejection fraction.

Management of aortic stenosis: a systematic review of clinical practice guidelines and recommendations

Multiple guidelines exist for the management of aortic stenosis (AS). We systematically reviewed current guidelines and recommendations, developed by national or international medical organizations, on management of AS to aid clinical decision-making. Publications in MEDLINE and EMBASE between 1 June 2010 and 15 January 2021 were identified. Additionally, the International Guideline Library, National Guideline Clearinghouse, National Library for Health Guidelines Finder, Canadian Medical Association Clinical Practice Guidelines Infobase, and websites of relevant organizations were searched. Two reviewers independently screened titles and abstracts. Two reviewers assessed rigour of guideline development and extracted the recommendations. Of the seven guidelines and recommendations retrieved, five showed considerable rigour of development. Those rigourously developed, agreed on the definition of severe AS and diverse haemodynamic phenotypes, indications and contraindications for intervention in symptomatic severe AS, surveillance intervals in asymptomatic severe AS, and the importance of multidisciplinary teams (MDTs) and shared decision-making. Discrepancies exist in age and surgical risk cut-offs for recommending surgical aortic valve replacement (SAVR) vs. transcatheter aortic valve implantation (TAVI), the use of biomarkers and complementary multimodality imaging for decision-making in asymptomatic patients and surveillance intervals for non-severe AS. Contemporary guidelines for AS management agree on the importance of MDT involvement and shared decision-making for individualized treatment and unanimously indicate valve replacement in severe, symptomatic AS. Discrepancies exist in thresholds for age and procedural risk used in choosing between SAVR and TAVI, role of biomarkers and complementary imaging modalities to define AS severity and risk of progression in asymptomatic patients.

High Prevalence of Severe Aortic Stenosis in Low-Flow State Associated With Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) is a low-flow state and may underestimate aortic stenosis (AS) severity. Single-high Doppler signals (HS) consistent with severe AS (peak velocity ≥4 m/s or mean gradient ≥40 mm Hg) are averaged down in current practice. The objective for the study was to determine the significance of HS in AF low-gradient AS (LGAS).

METHODS

One thousand five hundred forty-one patients with aortic valve area ≤1 cm² and left ventricular ejection fraction ≥50% were identified and classified as high-gradient AS (HGAS) (≥40 mm Hg) and LGAS (<40 mm Hg), and AF versus sinus rhythm (SR). Available computed tomography aortic valve calcium scores (AVCS) were retrieved from the medical record. Outcomes were assessed.

RESULTS

Mean age was 76±11 years, female 47%. Mean gradient was 51±12 in SR-HGAS, 48±10 in AF-HGAS, 31±5 in SR-LGAS, and 29±7 mm Hg in AF-LGAS, all P≤0.001 versus SR-HGAS; HS were present in 33% of AF-LGAS. AVCS were available in 34%. Compared with SR-HGAS (2409 arbitrary units; interquartile range, 1581-3462) AVCS were higher in AF-HGAS (2991 arbitrary units; IQR1978-4229, P=0.001), not different in AF-LGAS (2399 arbitrary units; IQR1817-2810, P=0.47), and lower in SR-LGAS (1593 arbitrary units; IQR945-1832, P<0.001); AVCS in AF-LGAS were higher when HS were present (P=0.048). Compared with SR-HGAS, the age-, sex-, comorbidity index-, and time-dependent aortic valve replacement-adjusted mortality risk was higher in AF-HGAS (hazard ratio=1.82 [1.40-2.36], P<0.001) and AF-LGAS with HS (hazard ratio=1.54 [1.04-2.26], P=0.03) but not different in AF-LGAS without HS or SR-LGAS (both P=not significant).

CONCLUSIONS

Severe AS was common in AF-LGAS. AVCS in AF-LGAS were not different from SR-HGAS. AVCS were higher and mortality worse in AF-LGAS when HS were present.

Dynamic nature of the LVOT following transcatheter mitral valve replacement with LAMPOON: new insights from post-procedure imaging

AIMS

To characterize the dynamic nature of the left ventricular outflow tract (LVOT) geometry and flow rate in patients following transcatheter mitral valve replacement (TMVR) with anterior leaflet laceration (LAMPOON) and derive insights to help guide future patient selection.

METHODS AND RESULTS

Time-resolved LVOT geometry and haemodynamics were analysed with post-procedure computed tomography and echocardiography in subjects (N = 19) from the LAMPOON investigational device exemption trial. A novel post hoc definition for LVOT obstruction was employed to account for systolic flow rate and quality of life improvement [obstruction was defined as LVOT gradient >30 mmHg or LVOT effective orifice area (EOA) ≤1.15 cm2]. The neo-LVOT and skirt neo-LVOT were observed to vary substantially in area throughout systole (64 ± 27% and 25 ± 14% change in area, respectively). The peak systolic flow rate occurred most commonly just prior to mid-systole, while minimum neo-LVOT (and skirt neo-LVOT) area occurred most commonly in early-diastole. Subjects with LVOT obstruction (n = 5) had smaller skirt neo-LVOT values across systole. Optimal thresholds for skirt neo-LVOT area were phase-specific (260, 210, 200, and 180 mm2 for early-systole, peak flow, mid-systole, and end-systole, respectively).

CONCLUSION

The LVOT geometry and flow rate exhibit dynamic characteristics following TMVR with LAMPOON. Subjects with LVOT obstruction had smaller skirt neo-LVOT areas across systole. The authors recommend the use of phase-specific threshold values for skirt neo-LVOT area to guide future patient selection for this procedure. LVOT EOA is a 'flow-independent' metric which has the potential to aid in characterizing LVOT obstruction severity.

Echocardiographic assessment of aortic stenosis: a practical guideline from the British Society of Echocardiography

The guideline provides a practical step-by-step guide in order to facilitate high-quality echocardiographic studies of patients with aortic stenosis. In addition, it addresses commonly encountered yet challenging clinical scenarios and covers the use of advanced echocardiographic techniques, including TOE and Dobutamine stress echocardiography in the assessment of aortic stenosis.

Sex differences in transaortic flow rate and association with all-cause mortality in patients with severe aortic stenosis

AIMS

It is not known whether transaortic flow rate (FR) in aortic stenosis (AS) differs between men and women, and whether the commonly used cut-off of 200 mL/s is prognostic in females. We aimed to explore sex differences in the determinants of FR, and determine the best sex-specific cut-offs for prediction of all-cause mortality.

METHODS AND RESULTS

Between 2010 and 2017, a total of 1564 symptomatic patients (mean age 76 ± 13 years, 51% men) with severe AS were prospectively included. Mean follow-up was 35 ± 22 months. The prevalence of cardiovascular disease was significantly higher in men than women (63% vs. 42%, P < 0.001). Men had higher left ventricular mass and lower left ventricular ejection fraction compared to women (both P < 0.001). Men were more likely to undergo an aortic valve intervention (AVI) (54% vs. 45%, P = 0.001), while the death rates were similar (42.0% in men and 40.6% in women, P = 0.580). A total of 779 (49.8%) patients underwent an AVI in which 145 (18.6%) died. In a multivariate Cox regression analysis, each 10 mL/s decrease in FR was associated with a 7% increase in hazard ratio (HR) for all-cause mortality (HR 1.07; 95% CI 1.03-1.11, P < 0.001). The best cut-off value of FR for prediction of all-cause mortality was 179 mL/s in women and 209 mL/s in men.

CONCLUSION

Transaortic FR was lower in women than men. In the group undergoing AVI, lower FR was associated with increased risk of all-cause mortality, and the optimal cut-off for prediction of all-cause mortality was lower in women than men.

Prognosis of Severe Low-Flow, Low-Gradient Aortic Stenosis by Stroke Volume Index and Transvalvular Flow Rate

OBJECTIVES

This study determined whether flow state classified by stroke volume index (SVi) or transvalvular flow rate (FR) improved risk stratification of all-cause mortality, hospitalization due to heart failure, and aortic valvular interventions for patients with severe aortic stenosis (AS).

BACKGROUND

SVi is a widely accepted classification for flow state in severe low-flow, low-gradient (LFLG) AS. Recent studies suggest that FR more closely approximates true AS severity and provides more useful prognostication than SVi.

METHODS

Patients with severe AS over a 7-year period were subclassified by echocardiographic parameters. LFLG-AS was defined as severe AS (aortic valve area index [AVAi]: <0.6 cm²/m²), with a mean transvalvular pressure gradient of <40 mm Hg in the setting of low flow state: SVi of <35 ml/m² and/or FR of <200 ml/s and subclassified into preserved (≥50%; paradoxical) or reduced (<50%; classical) left ventricular ejection fraction (LVEF).

RESULTS

Among 621 consecutive patients with severe AS, the proportions of patients classified as LFLG-AS were different between SVi and FR (p < 0.001). Classification using SVi, FR, and LVEF was a strong predictor of the composite endpoint at the 2-year follow-up. The addition of SVi to the echocardiographic and clinical model provided significant improvement in reclassification (net reclassification improvement: 0.089; 95% confidence interval [CI]: 0.045 to 0.133; p = 0.04), whereas addition of FR did not (net reclassification improvement: 0.061; 95% CI: 0.016 to 0.106; p = 0.17). C-statistics indicated improved risk discrimination when AVAi, LVEF, and SVi or FR were added as predictive variables to the clinical model (p = 0.006).

CONCLUSIONS

Low SVi or FR was associated with adverse cardiovascular events and showed improvement in discrimination, but only SVi, not FR, significantly improved risk reclassification compared to other conventional clinical and echocardiographic predictors. This suggests that FR is not superior to SVi in distinguishing true severe from pseudosevere forms of AS and identification of patients with LFLG-AS who have worse outcomes.

Watchful waiting care or early intervention in asymptomatic severe aortic stenosis: Where we are

Aortic stenosis, the most common valvular heart disease in Western countries, affects predominantly older people. Prompt aortic valve replacement is undoubtedly indicated in symptomatic patients. Management of asymptomatic patients is nowadays shifting from a conservative approach to early aortic valve replacement, as multimodality imaging is increasingly available. However, multimodality imaging has led to multiple prognostic parameters and complex algorithms, as well as a new staging classification that has left patients and physicians somewhat puzzled. We highlight the value of thorough serial clinical examinations, Doppler echocardiography and exercise testing when caring for a growing aortic stenosis population, including that has no or limited access to multimodality imaging. Evidence for early aortic valve replacement versus conservative management in asymptomatic patients with severe aortic stenosis is biased by the lack of serial stress testing evaluation; 30% of so-called asymptomatic patients were in fact symptomatic, and thus were clear candidates for aortic valve replacement in the above-mentioned studies. Randomized trials of aortic valve replacement versus conservative management that include serial stress testing evaluation are needed to ascertain whether early aortic valve replacement actually improves clinical outcome in asymptomatic patients with severe aortic stenosis. Less interventional medicine and healthcare resource utilization can result in better health.