Adjusting parameters of aortic valve stenosis severity by body size

Indexed aortic valve area using multimodality imaging for assessing the severity of bicuspid aortic stenosis

BACKGROUND

The impact of various imaging modalities on discordance/concordance between indexed aortic valve area (iAVA) and catheterization-derived mean transaortic pressure gradient (mPGcath) is unclear in patients with bicuspid aortic valve (BAV). This study aimed to compare iAVA measurements obtained using four different methodologies in BAV and tricuspid aortic valve (TAV) patients, using mPGcath as a reference standard.

METHODS

We retrospectively reviewed patients who underwent comprehensive assessment of AS, including two-dimensional (2D) transthoracic echocardiography (TTE), three-dimensional (3D) transesophageal echocardiography (TEE), multidetector computed tomography (MDCT), and catheterization, at our institution between 2019 and 2022. iAVA was measured using the continuity eq. (CE) with left ventricular outflow tract area obtained by 2D TTE, 3D TEE, and MDCT, as well as planimetric 3D TEE.

RESULTS AND CONCLUSIONS

Among 564 patients (64 with BAV and 500 with TAV), 64 propensity-matched pairs of patients with BAV and TAV were analyzed. iAVACE(2DTTE) led to overestimation of AS severity (BAV, 23.4%; TAV, 28.1%) and iAVACE(MDCT) led to underestimation of AS severity (BAV, 29.3%; TAV, 16.7%), whereas iAVACE(3DTEE) and iAVAPlani(3DTEE) resulted in a reduction in the discordance of AS grading. A moderate correlation was observed between mPGcath and iAVACE(3DTEE) (BAV, r = -0.63; TAV, r = -0.68), with iAVACE(3DTEE) corresponding to the current guidelines' cutoff value (BAV, 0.58 cm2/m2; TAV, 0.60 cm2/m2). Discordance/concordance between iAVA and mPGcath in evaluating AS severity varies depending on the methodology and imaging modality used. The use of iAVACE(3DTEE) is valuable for reconciling the discordant AS grading in BAV patients as well as TAV.

Genomic insights in ascending aortic size and distensibility

BACKGROUND

Alterations in the anatomic and biomechanical properties of the ascending aorta (AAo) can give rise to various vascular pathologies. The aim of the current study is to gain additional insights in the biology of the AAo size and function.

METHODS

We developed an AI based analysis pipeline for the segmentation of the AAo, and the extraction of AAO parameters. We then performed genome-wide association studies of AAo maximum area, AAo minimum area and AAo distensibility in up to 37,910 individuals from the UK Biobank. Variants that were significantly associated with AAo phenotypes were used as instrumental variables in Mendelian randomization analyses to investigate potential causal relationships with coronary artery disease, myocardial infarction, stroke and aneurysms.

FINDINGS

Genome-wide association studies revealed a total of 107 SNPs in 78 loci. We annotated 101 candidate genes involved in various biological processes, including connective tissue development (THSD4 and COL6A3). Mendelian randomization analyses showed a causal association with aneurysm development, but not with other vascular diseases.

INTERPRETATION

We identified 78 loci that provide insights into mechanisms underlying AAo size and function in the general population and provide genetic evidence for their role in aortic aneurysm development.

Size-adjusted aortic valve area: refining the definition of severe aortic stenosis

AIMS

Severe aortic valve stenosis (AS) is defined by an aortic valve area (AVA) <1 cm2 or an AVA indexed to body surface area (BSA) <0.6 cm/m2, despite little evidence supporting the latter approach and important intrinsic limitations of BSA indexation. We hypothesized that AVA indexed to height (H) might be more applicable to a wide range of populations and body morphologies and might provide a better predictive accuracy.

METHODS AND RESULTS

In 1298 patients with degenerative AS and preserved ejection fraction from three different countries and continents (derivation cohort), we aimed to establish an AVA/H threshold that would be equivalent to 1.0 cm2 for defining severe AS. In a distinct prospective validation cohort of 395 patients, we compared the predictive accuracy of AVA/BSA and AVA/H. Correlations between AVA and AVA/BSA or AVA/H were excellent (all R2 > 0.79) but greater with AVA/H. Regressions lines were markedly different in obese and non-obese patients with AVA/BSA (P < 0.0001) but almost identical with AVA/H (P = 0.16). AVA/BSA values that corresponded to an AVA of 1.0 cm2 were markedly different in obese and non-obese patients (0.48 and 0.59 cm2/m2) but not with AVA/H (0.61 cm2/m for both). Agreement for the diagnosis of severe AS (AVA < 1 cm2) was significantly higher with AVA/H than with AVA/BSA (P < 0.05). Similar results were observed across the three countries. An AVA/H cut-off value of 0.6 cm2/m [HR = 8.2(5.6-12.1)] provided the best predictive value for the occurrence of AS-related events [absolute AVA of 1 cm2: HR = 7.3(5.0-10.7); AVA/BSA of 0.6 cm2/m2 HR = 6.7(4.4-10.0)].

CONCLUSION

In a large multinational/multiracial cohort, AVA/H was better correlated with AVA than AVA/BSA and a cut-off value of 0.6 cm2/m provided a better diagnostic and prognostic value than 0.6 cm2/m2. Our results suggest that severe AS should be defined as an AVA < 1 cm2 or an AVA/H < 0.6 cm2/m rather than a BSA-indexed value of 0.6 cm2/m2.

Prognostic value of aortic valve area normalized to body size in native aortic stenosis

INTRODUCTION AND OBJECTIVES

Although guidelines recommend the use of a cutoff value of 0.60 cm²/m² for aortic valve area (AVA) normalized to body surface area (BSA) for severe aortic stenosis, there is little evidence of its prognostic value. Our aim was to test the value of AVA normalized to body size for outcome prediction in aortic stenosis.

METHODS

One-hundred and ninety patients with at least moderate aortic stenosis (AVA <1.50 cm²) were prospectively enrolled. AVA was normalized to BSA and height. The primary endpoint was cardiovascular death under medical management. A receiver operating characteristic curve was plotted to determine the best cutoff value for predicting cardiovascular death.

RESULTS

An AVA/BSA cutoff value of 0.50 had a sensitivity of 96% and specificity of 51%. An AVA/height cutoff value of 0.49 showed a sensitivity of 96% and a specificity of 52%. During a mean follow-up of 247±190 days, there were 24 cardiovascular deaths, with higher cardiovascular mortality in patients with AVA/BSA <0.50 cm²/m² (21% vs 2.5%, P <.001) and AVA/height <0.49 cm²/m (25% vs 12%, P <.001). Two-year survival was 95±5% in patients with AVA/BSA> 0.50 cm²/m² and was 37±5% in patients with AVA/BSA <0.50 cm²/m² (P <.001). Cardiovascular death risk was higher in patients with AVA/BSA <0.50 cm²/m² (adjusted 10.9 [1.2-103.7], P=.037), but cardiovascular mortality was not significantly higher in multivariate analysis for patients with AVA/height <0.49 cm²/m (2.0 [0.6-6.0], P=.22).

CONCLUSIONS

We could identify a subgroup of patients at high risk of cardiovascular death when they were medically treated. Consequently we recommend using an AVA/BSA cutoff value of 0.50 cm²/m² to identify a subgroup of patients with higher cardiovascular risk.

The contemporary role of echocardiography in the assessment and management of aortic stenosis

Aortic stenosis (AS) represents a major healthcare issue because of its ever-increasing prevalence, poor prognosis, and complex pathophysiology. Echocardiography plays a central role in providing a comprehensive morphological and hemodynamic evaluation of AS. The diagnosis of severe AS is currently based on three hemodynamic parameters including maximal jet velocity, mean pressure gradient (mPG) across the aortic valve, and aortic valve area (AVA). However, inconsistent grading of AS severity is common when the AVA is < 1.0 cm² but the mPG is < 40 mmHg, also known as low-gradient AS (LGAS). Special attention should be paid to patients with symptomatic LGAS with low stroke volume and/or low ejection fraction because this entity is more difficult to diagnose and has a worse prognosis. Stress echocardiography testing plays an important role in this disease entity. Elderly patients with prohibitive comorbidities for surgical aortic valve replacement (AVR) were without procedural options until the advent of transcatheter AVR (TAVR), which has dramatically changed these circumstances. Along with computed tomography, echocardiography plays a vital role in the periprocedural assessment of the aortic valve and surrounding apparatus. This review describes the evolution of the role of echocardiography in the diagnosis and management of AS, the complexity of the aortic apparatus, and the increased need for expert use of three-dimensional echocardiography.

Echocardiographic manifestations and chemical composition of stenotic bicuspid aortic valves

Bicuspid aortic valve (BAV) is an inherited form of heart disease with only two aortic valve leaflets via a disorder of cardiac valvulogenesis. We investigated the in vivo echocardiographic features of cardiac morphology in patients with BAV and the ex vivo compositional components of all the excised BAV leaflets isolated from BAV patients. Three BAV patients were randomly selected. All patients underwent 2D transthoracic echocardiography (TTE) with a Doppler ultrasound tool. The compositional components of each respective BAV leaflet for all the excised BAVs were determined by a portable fiber-optic Raman spectroscopy. Preoperative TTE revealed the thickened and calcified BAV leaflets, and stenotic aortic flow for all BAV patients. These BAV patients exhibited severe aortic stenosis (AS) by the lower values of aortic valve area (AVA) index. One patient showed a more significant left ventricle hypertrophy, whereas two patients exhibited a significant aortic regurgitation (AR). In addition, three different Raman spectral patterns were summed up from 121 randomized Raman determinations for all the excised BAV leaflets. The main calcified deposition in each BAV leaflet was formed by large amounts of calcium hydroxyapatite and type-B carbonate apatite (Raman bands at 960 and 1070 cm^-1). The calcified BAV leaflets were composed of different compositional components such as calcium hydroxyapatite, type-B carbonate apatite, lipids, proteins, cholesterol and β-carotene. The rare NL subtype of type 1 BAV morphotype was found in one patient, but two patients had the purely BAV morphotype with two equal-sized leaflets.

Longitudinal Assessment of the Doppler-Estimated Maximum Gradient in Patients With Congenital Valvar Aortic Stenosis Pre- and Post-Balloon Valvuloplasty

BACKGROUND

Aortic stenosis has been reported to manifest a slow rate of progression in mild disease, with a greater likelihood of progression in patients with moderate-severe disease. The natural history of the Doppler-estimated maximum gradient (DEMG) in patients after balloon aortic valvuloplasty (BAVP) has not previously been studied on a large scale.

METHODS AND RESULTS

A retrospective review was performed of 360 patients from 1984 to 2012 with aortic stenosis, providing a total of 2059 echocardiograms both before and after BAVP. Patients were excluded if they had an intervention within the first 30 days of life. The relationships between the aortic stenosis DEMG and several predictors (age at initial study, body surface area, valve morphology, and initial DEMG) were explored using linear mixed effect models. Patients with a unicommissural aortic valve had a significantly higher rate of progression compared with those with a bicommissural aortic valve (0.81 and 0.45 mm Hg/year; P<0.001). The median rate of progression in the post-BAVP group was significantly lower than the median pre-BAVP rate of progression (n=34; pre-BAVP 3.97 [1.69-8.7] mm Hg/year; post-BAVP 0.40 [-1.80 to 3.88] mm Hg/year; P<0.008). When adjusted for body surface area, there was no significant increase in the DEMG (-0.03 mm Hg/m² per year; P<0.001).

CONCLUSIONS

There is a statistically significant increase in the DEMG over time in patients with aortic stenosis. After balloon dilation, the DEMG rate of change is reduced compared with that pre-dilation. Given the effect of body surface area on DEMG progression, more frequent observation should be made during periods of rapid somatic growth.

Outcome Implication of Aortic Valve Area Normalized to Body Size in Asymptomatic Aortic Stenosis

Background—

Current guidelines define severe aortic stenosis in patients with aortic valve area normalized to body surface area (AVA/BSA) <0.6 cm 2 /m 2 ; yet, this cutoff has never been validated. Moreover, it is not known whether AVA normalization to other body size indexes allows improved outcome prediction. We aim to test the value of AVA normalized to body size for outcome prediction in asymptomatic aortic stenosis.

Methods and Results—

We included 289 patients with asymptomatic aortic stenosis, preserved ejection fraction, and AVA<1.3 cm 2 at diagnosis. The outcome measure was the occurrence of aortic valve replacement or all-cause death or during follow-up. AVA was normalized to BSA, height, weight, and body mass index. For each normalized index, patients in the lowest tertile were at high risk of events whereas outcome was similar for the other tertiles. High risk of events was observed with AVA/BSA <0.4 cm 2 /m 2 (adjusted hazard ratio [HR], 3.42 [2.09–5.60]), AVA/height <0.45 cm 2 /m (adjusted HR, 3.99 [2.42–6.60]), AVA/weight <0.01 cm 2 /kg (adjusted HR, 3.37 [2.07–5.49]), and AVA/body mass index <0.029 cm 2 /kg per meter square (adjusted HR, 3.23 [1.99–5.24]). Mortality risk was high with AVA/height <0.45 cm 2 /m (adjusted HR, 2.18 [1.28–3.71]), followed by AVA/BSA <0.40 cm 2 /m 2 (adjusted HR, 1.84 [1.09–3.11]), AVA/weight <0.01 cm 2 /kg (adjusted HR, 1.78 [1.07–2.98]), and AVA/body mass index <0.029 cm 2 /kg per meter square (adjusted HR, 1.75 [1.04–2.93]). AVA/height showed better predictive performance than AVA/BSA with improved reclassification and better discrimination (net reclassification improvement: 0.33 versus 0.28; integrated discrimination improvement: 0.10 versus 0.08; C statistic: 0.67 versus 0.65), whereas AVA/weight and AVA/body mass index showed lower predictive capacity.

Conclusions—

Among AVA normalization methods, AVA/height <0.45 cm 2 /m followed by AVA/BSA <0.40 cm 2 /m 2 seem as robust parameters for defining high risk in asymptomatic aortic stenosis. The prognostic value of AVA/height deserves future research.

Low gradient aortic stenosis

OPINION STATEMENT

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

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

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