Doppler Imaging in Aortic Stenosis: The Importance of the Nonapical Imaging Windows to Determine Severity in a Contemporary Cohort

High- versus low-gradient aortic stenosis: Is our evaluation limited by aorto-mitral angle on cardiovascular CT?

BACKGROUND

Accurate assessment of aortic valve (AV) stenosis (AS) on transthoracic echocardiogram is crucial for appropriate clinical management. However, discordance between aortic valve area (AVA) and Doppler can complicate the diagnosis of severe AS in low-gradient (LG) AS phenotypes.

METHODS

We reviewed 220 consecutive patients with suspected severe AS and AVA ≤1.0 cm2 on transthoracic echocardiogram who were evaluated for transcatheter AV replacement (TAVR) within a large health system from 2015 to 2019. We compared AV calcium score and aorto-mitral angle (AMA) on 3-chamber views from ECG-gated cardiovascular CT among patients with high-gradient (HG) AS (N = 19), paradoxical low-flow low-gradient (PLFLG) AS (N = 24) and normal-flow low-gradient (NFLG) AS (N = 14).

RESULTS

All groups had comparable age, comorbidities, and AV calcium scores. Compared to patients with HG AS (mean AMA 120 ± 10°), those with PLFLG AS (104 ± 12°; p < 0.001) and NFLG AS (106 ± 13°; p = 0.008) had narrower mean AMA values on cardiovascular CT.

CONCLUSION

LG AS patients have significantly narrower AMA than HG AS patients on cardiovascular CT. Due to difficulty obtaining parallel Doppler alignment, narrower AMA may contribute to AVA-Doppler discordance on echocardiogram. These findings emphasize the need for additional information in the setting of LG AS.

Predominant determinants for evaluation of right parasternal approach in transthoracic echocardiography in aortic stenosis: a study based on three-dimensional cardiac computed tomography analysis

The maximum blood flow velocity through the aortic valve (AVmax) using Doppler transthoracic echocardiography (TTE) is important in assessing the severity of aortic stenosis (AS). The right parasternal (RP) approach has been reported to be more useful than the apical approach, but the anatomical rationale has not been studied. We aimed to clarify the influence of the angle formed by the ascending aorta and left ventricle on Doppler analysis by TTE (Sep-Ao angle) and three-dimensional multidetector computed tomography (3D-MDCT) in patients with AS. A total of 151 patients evaluated using the RP approach and 3D-MDCT were included in this study. The Sep-Ao angle determined using TTE was compared with that determined using 3D-MDCT analysis. In MDCT analysis, the left ventricular (LV) axis was measured in two ways and the calcification score was calculated simultaneously. The Sep-Ao angle on TTE was consistent with that measured using 3D-MDCT. In patients with an acute Sep-Ao angle, the Doppler angle in the apical approach was larger, potentially underestimating AVmax. Multivariate analysis revealed that an acute Sep-Ao angle, large Doppler angle in the apical approach, smaller Doppler angle in the RP approach, and low aortic valve calcification were independently associated with a higher AVmax in the RP approach than in the apical approach. The Sep-Ao angle measured using TTE reflected the 3D anatomical angle. In addition to measurements using the RP approach, technical adjustments to minimize the Doppler angle to avoid bulky calcification should always be noted for accurate assessment.

Examining the typical hemodynamic performance of nearly 3000 modern surgical aortic bioprostheses

OBJECTIVES

The objective of this analysis was to assess the normal haemodynamic performance of contemporary surgical aortic valves at 1 year postimplant in patients undergoing surgical aortic valve replacement for significant valvular dysfunction. By pooling data from 4 multicentre studies, this study will contribute to a better understanding of the effectiveness of surgical aortic valve replacement procedures, aiding clinicians and researchers in making informed decisions regarding valve selection and patient management.

METHODS

Echocardiograms were assessed by a single core laboratory. Effective orifice area, dimensionless velocity index, mean aortic gradient, peak aortic velocity and stroke volume were evaluated.

RESULTS

The cohort included 2958 patients. Baseline age in the studies ranged from 70.1 ± 9.0 to 83.3 ± 6.4 years, and Society of Thoracic Surgeons risk of mortality was 1.9 ± 0.7 to 7.5 ± 3.4%. Twenty patients who had received a valve model implanted in fewer than 10 cases were excluded. Ten valve models (all tissue valves; n = 2938 patients) were analysed. At 1 year, population mean effective orifice area ranged from 1.46 ± 0.34 to 2.12 ± 0.59 cm2, and dimensionless velocity index, from 0.39 ± 0.07 to 0.56 ± 0.15. The mean gradient ranged from 8.6 ± 3.4 to 16.1 ± 6.2 mmHg with peak aortic velocity of 1.96 ± 0.39 to 2.65 ± 0.47 m/s. Stroke volume was 75.3 ± 19.6 to 89.8 ± 24.3 ml.

CONCLUSIONS

This pooled cohort is the largest to date of contemporary surgical aortic valves with echocardiograms analysed by a single core lab. Overall haemodynamic performance at 1 year ranged from good to excellent. These data can serve as a benchmark for other studies and may be useful to evaluate the performance of bioprosthetic surgical valves over time.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02088554, NCT02701283, NCT01586910 and NCT01531374.

Diagnostic Contexts of Echocardiographic Nonapical Window

The long-established utility of multiwindow interrogation in echocardiography (suprasternal notch, right and left sternal border, apex, and subxiphoid) is sometimes not systematically implemented in routine practice. This case series emphasizes the pivotal importance of such practice for the systematic assessment of aortic valve stenosis and in the evaluation of left ventricular outflow tract and the aorta.

Doppler Echocardiographic Phenotypes in Suspected 'Severe' Aortic Stenosis: Matrix-Based Approach to Diagnosis and Management

BACKGROUND

Among patients with suspected severe aortic stenosis (AS), Doppler echocardiographic (DE) data are often discordant, and further analysis is required for accurate diagnosis and optimal management. In this study, an automated matrix-based approach was applied to an echocardiographic database of patients with AS that identified 5 discrete echocardiographic data patterns, 1 concordant and 4 discordant, each reflecting a particular pathophysiology/measurement error that guides further workup and management.

METHODS

A primary/discovery cohort of consecutive echocardiographic studies with at least 1 DE parameter of severe AS and analogous data from an independent secondary/validation cohort were retrospectively analyzed. Parameter thresholds for inclusion were aortic valve area (AVA) <1.0 cm2, transaortic mean gradient (MG) ≥ 40 mmHg, and/or transaortic peak velocity (PV) ≥ 4.0 m/sec. Doppler velocity index (DVI) was also determined. Logic provided by an in-line SQL query embedded within the database was used to assign each patient to 1 of 5 discrete matrix patterns, each reflecting 1 or more specific pathophysiologies. Feasibility of automated pattern-driven triage of discordant cases was also evaluated.

RESULTS

In both cohorts, data from each patient fitted only 1 data pattern. Of the 4,643 primary cohort patients, 39% had concordant parameters for severe AS and DVI <0.30 (pattern 1); 35% had AVA < 1.0 cm2, MG < 40 mm Hg, PV < 4 m/sec, DVI < 0.30 (pattern 2); 9% had MG ≥ 40 mmHg and/or PV ≥ 4 m/sec, DVI > 0.30 (pattern 3); 10% had AVA < 1.0 cm2, MG < 40 mmHg, PV < 4 m/sec, DVI >0.30 (pattern 4); and 7% had MG > 40 mmHg and/or PV ≥ 4 m/sec, AVA > 1.0 cm2, DVI < 0.30 (pattern 5). Findings were validated among the 387 secondary cohort patients in whom pattern distribution was remarkably similar.

CONCLUSIONS

Matrix-based pattern recognition permits automated in-line identification of specific pathophysiology and/or measurement error among patients with suspected severe AS and discordant DE data.

Aortic Valve Calcium Score by Computed Tomography as an Adjunct to Echocardiographic Assessment-A Review of Clinical Utility and Applications

Aortic valve stenosis (AS) is increasing in prevalence due to the aging population, and severe AS is associated with significant morbidity and mortality. Echocardiography remains the mainstay for the initial detection and diagnosis of AS, as well as for grading of severity. However, there are important subgroups of patients, for example, patients with low-flow low-gradient or paradoxical low-gradient AS, where quantification of severity of AS is challenging by echocardiography and underestimation of severity may delay appropriate management and impart a worse prognosis. Aortic valve calcium score by computed tomography has emerged as a useful clinical diagnostic test that is complimentary to echocardiography, particularly in cases where there may be conflicting data or clinical uncertainty about the degree of AS. In these situations, aortic valve calcium scoring may help re-stratify grading of severity and, therefore, further direct clinical management. This review presents the evolution of aortic valve calcium score by computed tomography, its diagnostic and prognostic value, as well as its utility in clinical care.

Improving accuracy in diagnosing aortic stenosis severity: An in-depth analysis of echocardiographic measurement error through literature review and simulation study

AIMS

The present guidelines advise replacing the aortic valve for individuals with severe aortic stenosis (AS) based on various echocardiographic parameters. Accurate measurements are essential to avoid misclassification and unnecessary interventions. The objective of this study was to evaluate the influence of measurement error on the echocardiographic evaluation of the severity of AS.

METHODS AND RESULTS

A systematic review was performed to examine whether measurement errors are reported in studies focusing on the prognostic value of peak aortic jet velocity (Vmax ), mean pressure gradient (MPG), and effective orifice area (EOA) in asymptomatic patients with AS. Out of the 37 studies reviewed, 17 (46%) acknowledged the existence of measurement errors, but none of them utilized methods to address them. Secondly, the magnitude of potential errors was collected from available literature for use in clinical simulations. Interobserver variability ranged between 0.9% and 8.3% for Vmax and MPG but was higher for EOA (range 7.7%-12.7%), indicating lower reliability. Assuming a circular left ventricular outflow tract area led to a median underestimation of EOA by 23% compared to planimetry by other modalities. A clinical simulation resulted in the reclassification of 42% of patients, shifting them from a diagnosis of severe AS to moderate AS.

CONCLUSIONS

Measurement errors are underreported in studies on echocardiographic assessment of AS severity. These errors can lead to misclassification and misdiagnosis. Clinicians and scientists should be aware of the implications for accurate clinical decision-making and assuring research validity.

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.

Correlation between artificial intelligence-enabled electrocardiogram and echocardiographic features in aortic stenosis

Aims

An artificial intelligence-enabled electrocardiogram (AI-ECG) is a promising tool to detect patients with aortic stenosis (AS) before developing symptoms. However, functional, structural, or haemodynamic components reflected in AI-ECG responsible for its detection are unknown.

Methods and results

The AI-ECG model that was developed at Mayo Clinic using a convolutional neural network to identify patients with moderate-severe AS was applied. In patients used as the testing group, the correlation between the AI-ECG probability of AS and echocardiographic parameters was investigated. This study included 102 926 patients (63.0 ± 16.3 years, 52% male), and 28 464 (27.7%) were identified as AS positive by AI-ECG. Older age, atrial fibrillation, hypertension, diabetes, coronary artery disease, and heart failure were more common in the positive AI-ECG group than in the negative group (P < 0.001). The AI-ECG was correlated with aortic valve area (ρ = -0.48, R² = 0.20), peak velocity (ρ = 0.22, R² = 0.08), and mean pressure gradient (ρ = 0.35, R² = 0.08). The AI-ECG also correlated with left ventricular (LV) mass index (ρ = 0.36, R² = 0.13), E/e' (ρ = 0.36, R² = 0.12), and left atrium volume index (ρ = 0.42, R² = 0.12). Neither LV ejection fraction nor stroke volume index had a significant correlation with the AI-ECG. Age correlated with the AI-ECG (ρ = 0.46, R² = 0.22) and its correlation with echocardiography parameters was similar to that of the AI-ECG.

Conclusion

A combination of AS severity, diastolic dysfunction, and LV hypertrophy is reflected in the AI-ECG to detect AS. There seems to be a gradation of the cardiac anatomical/functional features in the model and its identification process of AS is multifactorial.

Advantages of Multiposition Scanning in Echocardiographic Assessment of the Severity of Discordant Aortic Stenosis

AIM OF THE STUDY

The aim of this study was to perform a comparative analysis of severity of discordant aortic stenosis (AS) assessment using multiposition scanning and the standard apical window.

MATERIALS AND METHODS

All patients (n = 104) underwent preoperative transthoracic echocardiography (TTE) and were ranked according to the degree of AS severity. The reproducibility feasibility of the right parasternal window (RPW) was 75.0% (n = 78). The mean age of the patients was 64 years, and 40 (51.3%) were female. In 25 cases, low gradients were identified from the apical window not corresponding to the visual structural changes in the aortic valve, or disagreement between the velocity and calculated parameters was detected. Patients were divided into two groups: concordant AS (n = 56; 71.8%) and discordant AS (n = 22; 28.2%). Three individuals were excluded from the discordant AS group due to the presence of moderate stenosis.

RESULTS

Based on the comparative analysis of transvalvular flow velocities obtained from multiposition scanning, the concordance group showed agreement between the velocity and calculated parameters. We observed an increase in the mean transvalvular pressure gradient (ΔP_mean) and peak aortic jet velocity (V_max), ΔP_mean in 95.5% of patients, velocity time integral of transvalvular flow (VTI AV) in 90.9% of patients, and a decrease in aortic valve area (AVA) and indexed AVA in 90.9% of patients after applying RPW in all patients with discordant AS. The use of RPW allowed the reclassification of AS severity from discordant to concordant high-gradient AS in 88% of low-gradient AS cases.

CONCLUSION

Underestimation of flow velocity and overestimation of AVA using the apical window may lead to misclassification of AS. The use of RPW helps to match the degree of AS severity with the velocity characteristics and reduce the number of low-gradient AS cases.

Normalizing arterial blood pressure in patients with aortic stenosis does not prevent grading discrepancies between pre-cardiopulmonary bypass transesophageal echocardiography and transthoracic echocardiography

Background

Aortic stenosis (AS) grading discrepancies exist between pre-cardiopulmonary (pre-CPB) transesophageal echocardiography (TEE) and preoperative transthoracic echocardiography (TTE). Prior studies have not systematically controlled blood pressure.

Aims

We hypothesized that normalizing arterial blood pressure during pre-CPB TEE for patients undergoing valve replacement for AS would result in equivalent grading measurements when compared to TTE.

Setting

Single University Hospital.

Design

Prospective, Interventional.

Methods

Thirty-five adult patients underwent procedures for valvular AS between February 2017 and December 2020 at Medical University of South Carolina. Study participants had a TTE within 90 days of their procedure that documented blood pressure, peak velocity (Vp), mean gradient (PGm), aortic valve area (AVA), and dimensionless index (DI). During pre-CPB TEE, if a patient's mean arterial pressure (MAP) fell more than 20% below their baseline blood pressure obtained during TTE, measurements were recorded as "out of range." Phenylephrine was administered to restore MAP to the baseline range and repeat TEE measurements were recorded as "in-range."

Statistical Analysis

Differences between imaging modalities and grading parameters were examined using a series of linear mixed models. P values were Bonferroni-adjusted to account for multiple comparisons.

Main Results

Significant discrepancies between TEE and TTE were observed for Vp, PGm, and DI despite blood pressure normalization across all subjects and for out-of-range measures and corrected measures. There were no statistically significant differences between TEE and TTE for AVA.

Conclusions

Blood pressure normalization during pre-CPB TEE is not sufficient to avoid AS grading discrepancies with preoperative TTE.

Application of a Novel Two-Dimensional Echocardiographic Calcium Quantification Method to Assess All Severities of Aortic Stenosis

BACKGROUND

Aortic valve (AV) calcification (AVC) is a strong predictor of aortic stenosis (AS) severity. The two-dimensional AVC (2D-AVC) ratio, a gain-independent ratio composed of the average pixel density of the AV and the aortic annulus, has previously shown strong correlations with two-dimensional (2D) echocardiographic hemodynamic parameters for severe AS and AVC by cardiac computed tomography. We hypothesize that the 2D-AVC ratio correlates with hemodynamic parameters in all severities of AS.

METHODS

A total of 285 patients with a normal AV (n = 49), aortic sclerosis (n = 75), or mild (n = 38), moderate (n = 72), or severe (n = 51) AS undergoing 2D echocardiography were retrospectively evaluated, and the 2D-AVC ratios were correlated to mean AV gradient, peak AV velocity, AV area, and dimensionless index. The 2D-AVC ratios of various AS severities were compared against each other via area under the curve (AUC) analysis.

RESULTS

The 2D-AVC ratio is strongly correlated with mean AV gradient (r = 0.79, P < .0001) and peak AV velocity (r = 0.78, P < .0001). There was moderate correlation with the AV area (r = -0.58, P < .0001) and dimensionless index (r = -0.67, P < .0001) across all AS severities. The 2D-AVC ratio also distinguished nonmoderate AS (mild AS + normal AV) from moderate or greater (moderate + severe) AS (AUC = 0.93) and moderate versus severe AS (AUC = 0.88).

CONCLUSION

The 2D-AVC ratio exhibits moderate to strong correlation with 2D echocardiographic hemodynamic parameters across all severities of AS.

Additive value of the right parasternal view for the assessment of aortic stenosis

BACKGROUND

Although Doppler evaluation using a multiplanar method is recommended to assess the severity of aortic stenosis (AS) with transthoracic echocardiography, evidence on the diagnostic significance of a non-apical method is limited. This study aimed to compare the use of the apical with the use of the right parasternal view (RPV) method to evaluate AS severity and to examine the diagnostic significance of performing the RPV method in addition to the apical method during the evaluation.

METHODS

This retrospective observational study included 276 consecutive patients (mean age: 79 ± 10 years; women, 56%) with severe AS (aortic valve area [AVA] ≤1.0cm² ). The severity of AS according to the apical method and that according to the RPV for all subjects were compared, and the significance of performing the RPV method in addition to the apical method was examined. Furthermore, we compared the concordance group, in which the apical and RPV methods indicated matching in severity, and the discordant group, in which the apical and RPV methods did not indicate matching severity.

RESULTS

Peak velocity (V_max ), mean pressure gradient (MG) were significantly higher and the AVA, AVAi, and Doppler velocity index (DVI) were significantly smaller when the RPV was added to the apical view. Performing the RPV method in addition to the apical method significantly decreased the number of low PG AS cases (MG < 40 mmHg) from 69.9% to 65.0% and it increased the number of very severe AS cases (V_max ≥ 5 m/s) from 8.7% to 14.5%. Deviation of Doppler angle was significantly greater in the discordant group compared to the concordant group (22.5 ± .6 vs. 31.8 ± 1.7, p < .001).

CONCLUSIONS

By performing the RPV method in addition to the apical method to determine AS severity, the diagnosis of AS to be resolved in approximately 10% of cases. These results suggest that AS severity may be underestimated by using the apical method alone.

Confirmation of Aortic Stenosis Severity in Case of Discordance Between Aortic Valve Area and Gradient

In this report, we illustrate the different flow-gradient patterns of aortic stenosis associated with discordant grading of stenosis severity at transthoracic echocardiography (TTE). The discordance among TTE parameters (mean gradient and aortic area) can be reconciled and true severity can be confirmed by ruling out potential measurements errors and by using multimodality imaging. (Level of Difficulty: Advanced.)

Comparison of Simultaneous Transthoracic Versus Transesophageal Echocardiography for Assessment of Aortic Stenosis

Transthoracic echocardiography (TTE) is the gold standard for aortic stenosis (AS) assessment. Transesophageal echocardiography (TEE) provides better resolution, but its effect on AS assessment is unclear. To answer this question, we studied 56 patients with ≥moderate AS. Initial TTE (TTE1) was followed by conscious sedation with simultaneous TEE and TTE2. Based on conservative versus actionable implication, AS types were dichotomized into group A, comprising moderate and normal-flow low-gradient, and group B, comprising high gradient, low ejection fraction low-flow low-gradient, and paradoxical low-flow low-gradient AS. Paired analysis of echocardiographic variables and AS types measured by TEE versus TTE2 and by TEE versus TTE1 was performed. TEE versus simultaneous TTE2 comparison demonstrated higher mean gradients (31.7 ± 10.5 vs 27.4 ± 10.5 mm Hg) and velocities (359 ± 60.6 vs 332 ± 63.1 cm/s) with TEE, but lower left ventricular outflow velocity-time-integral (VTI₁) (18.6 ± 5.1 vs 20.2 ± 6.1 cm), all p <0.001. This resulted in a lower aortic valve area (0.8 ± 0.21 vs 0.87 ± 0.28 cm²), p <0.001, and a net relative risk of 1.86 of group A to B upgrade. TEE versus (awake state) TTE1 comparison revealed a larger decrease in VTI₁ because of a higher initial awake state VTI₁ (22 ± 5.6 cm), resulting in similar Doppler-velocity-index and aortic valve area decrease with TEE, despite a slight increase in mean gradients of 0.8 mm Hg (confidence interval -1.44 to 3.04) and velocities of 10 cm/s (confidence interval -1.5 to 23.4). This translated into a net relative risk of 1.92 of group A to B upgrade versus TTE1. In conclusion, TEE under conscious sedation overestimates AS severity compared with both awake state TTE and simultaneous sedation state TTE, accounted for by different Doppler insonation angles obtained in transapical versus transgastric position.

Unequivocal interpretation of dobutamine stress echocardiography in low-flow, low-gradient aortic stenosis by right parasternal view

We present the case of a 77-years-old man with aortic valve stenosis (AS) and reduced left ventricular ejection fraction, in whom right parasternal view provided the best hemodynamic evaluation of AS severity during dobutamine stress echocardiography.

Value of non-apical echocardiographic views in the up-grading of patients with aortic stenosis

Purpose. Echocardiography assessment from apical five-chamber view (A5CV) is the standard technique for aortic stenosis (AS) grading. Data on non-apical views, such as right parasternal (RPV), subcostal (SCV) and suprasternal notch (SSNV), is scarce and constitutes the aim of our study. Methods. We designed an observational study that included patients with AS recruited prospectively in whom the stenosis was graded by echocardiography from A5CV and non-apical view. The value of non-apical views in up-grading the stenosis severity (primary objective), the prognostic relevance of such reclassification and the feasibility and reproducibility of non-apical views assessment (secondary objectives) was evaluated. Results. Feasibility of AS appraisal from RPV, SCV and SSNV was 78%, 81% and 56%, respectively (SCV vs SSNV, p = .009). AS were up-graded from non-apical views according to peak gradient, mean gradient, area and indexed area by 24%, 17%, 24% and 22%, respectively (p < .0001). Non-apical views reclassified from non-severe to severe AS, from low gradient severe to high gradient severe AS and from non-critical to critical AS 19%, 23% and 3% of cases (p < .0001). The 4-years hard cardiac events rate was 41% in patients with non-severe AS, 67% in patients with severe AS from non-apical views, 68% in patients with severe AS from A5CV and 80% in patients with severe AS from A5CV and non-apical views (p < .001). Reproducibility of AS evaluation from non-apical views was fair to excellent (intraclass correlation coefficients: SSNV = 0.44, RPV = 0.61, SCV = 0.92). Conclusion. Assessment of AS from non-apical views is feasible, reproducible and valuable over A5CV; its use is encouraged.

Spectrum bias in algorithms derived by artificial intelligence: a case study in detecting aortic stenosis using electrocardiograms

Aims

Spectrum bias can arise when a diagnostic test is derived from study populations with different disease spectra than the target population, resulting in poor generalizability. We used a real-world artificial intelligence (AI)-derived algorithm to detect severe aortic stenosis (AS) to experimentally assess the effect of spectrum bias on test performance.

Methods and results

All adult patients at the Mayo Clinic between 1 January 1989 and 30 September 2019 with transthoracic echocardiograms within 180 days after electrocardiogram (ECG) were identified. Two models were developed from two distinct patient cohorts: a whole-spectrum cohort comparing severe AS to any non-severe AS and an extreme-spectrum cohort comparing severe AS to no AS at all. Model performance was assessed. Overall, 258 607 patients had valid ECG and echocardiograms pairs. The area under the receiver operator curve was 0.87 and 0.91 for the whole-spectrum and extreme-spectrum models, respectively. Sensitivity and specificity for the whole-spectrum model was 80% and 81%, respectively, while for the extreme-spectrum model it was 84% and 84%, respectively. When applying the AI-ECG derived from the extreme-spectrum cohort to patients in the whole-spectrum cohort, the sensitivity, specificity, and area under the curve dropped to 83%, 73%, and 0.86, respectively.

Conclusion

While the algorithm performed robustly in identifying severe AS, this study shows that limiting datasets to clearly positive or negative labels leads to overestimation of test performance when testing an AI algorithm in the setting of classifying severe AS using ECG data. While the effect of the bias may be modest in this example, clinicians should be aware of the existence of such a bias in AI-derived algorithms.

The right parasternal window: when Doppler-beam alignment may be life-saving in patients with aortic valve stenosis

: The need for multiple transducer positions, especially from right parasternal windows, is consistently mentioned in the recommendations for the accurate measurement of peak velocities across a stenotic aortic valve, but yet poorly adopted.We performed a subanalysis of the largest prospective series on the right parasternal acoustic windows in patients with aortic stenosis (330 consecutive) to calculate the degree of misalignment and estimate the potential outcome implication of this often-forgotten approach.The right parasternal view was highly feasible with an average estimated misalignment from the apical view of 14 ± 16 degree; in 10 cases, an estimated misalignment >40 degree. Right parasternal assessment (vs. apical alone) provided a significant reclassification from moderate to severe or even very-severe aortic valve stenosis. Considering a wellestablished survival benefit provided by either percutaneous or surgical valve replacement in patients with severe aortic stenosis the reclassification would result in approximately 1 life-year saved for every 30-35 patients in whom parasternal view were effectively utilized.

Electrocardiogram screening for aortic valve stenosis using artificial intelligence

AIMS

Early detection of aortic stenosis (AS) is becoming increasingly important with a better outcome after aortic valve replacement in asymptomatic severe AS patients and a poor outcome in moderate AS. We aimed to develop artificial intelligence-enabled electrocardiogram (AI-ECG) using a convolutional neural network to identify patients with moderate to severe AS.

METHODS AND RESULTS

Between 1989 and 2019, 258 607 adults [mean age 63 ± 16.3 years; women 122 790 (48%)] with an echocardiography and an ECG performed within 180 days were identified from the Mayo Clinic database. Moderate to severe AS by echocardiography was present in 9723 (3.7%) patients. Artificial intelligence training was performed in 129 788 (50%), validation in 25 893 (10%), and testing in 102 926 (40%) randomly selected subjects. In the test group, the AI-ECG labelled 3833 (3.7%) patients as positive with the area under the curve (AUC) of 0.85. The sensitivity, specificity, and accuracy were 78%, 74%, and 74%, respectively. The sensitivity increased and the specificity decreased as age increased. Women had lower sensitivity but higher specificity compared with men at any age groups. The model performance increased when age and sex were added to the model (AUC 0.87), which further increased to 0.90 in patients without hypertension. Patients with false-positive AI-ECGs had twice the risk for developing moderate or severe AS in 15 years compared with true negative AI-ECGs (hazard ratio 2.18, 95% confidence interval 1.90-2.50).

CONCLUSION

An AI-ECG can identify patients with moderate or severe AS and may serve as a powerful screening tool for AS in the community.

Usefulness of the Right Parasternal Echocardiographic View to Improve the Hemodynamic Assessment After Valve Replacement for Aortic Stenosis

Right-parasternal-view (RPV) often provides the best hemodynamic assessment of the aortic-valve-stenosis by echocardiography. However, no detailed study on patients with aortic prosthesis is available. Thus, RPV usefulness is left as an anecdotical notion in this context. We aimed to define feasibility and clinical-impact of RPV before and soon-after percutaneous implantation (TAVI) or surgical (SAVR) aortic-valve-replacement (AVR) for AS. Patients with severe-AS electively referred for AVR between September-2019 and February-2020 were prospectively evaluated. Echocardiographic examinations inclusive of apical and RPV to measure aortic-peak-velocity , gradients and area (AVA) were performed the day before AVR and at hospital discharge and compared by matched-pair-analysis. Forty-seven patients (mean age 79 ± 8 years, 63% female, ejection-fraction 61 ± 6%) referred for SAVR (24 [51%]) or TAVI (23 [49%]) were enrolled. RPV was feasible in 45 patients (96%) before-AVR but in only 32 after-AVR (68%), particularly after SAVR (50%) than TAVI (87% p = 0.005). RPV remained the best acoustic window after TAVI in 75% of cases. Hemodynamic assessment of TAVI, but not SAVR, invariably benefit from RPV versus apical evaluation (aortic-peak-velocity: 2.57 ± 0.39 vs 2.23 ± 0.47 m/sec, p = 0.002; mean gradient: 15 ± 5 vs 12 ± 5 mm Hg, p = 0.01). Five (11%) patients presented severe patient-prosthesis-mismatch, 4 of which were detectable only by RPV. This pilot-experience demonstrates that RPV feasibility is slightly reduced after AVR. RPV can improve the hemodynamic assessment of the prosthetic valve versus apical view, including the detection of patient-prosthesis-mismatch. Furthermore, when RPV is the best acoustic windows in patients with severe AS, it generally remains so after-TAVI.

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.

Clinical significance of energy loss index in patients with low-gradient severe aortic stenosis and preserved ejection fraction

Aims 

We hypothesized that among patients with low-gradient severe aortic stenosis (AS) and preserved left ventricular ejection fraction (LVEF), reclassification of AS severity as moderate by pressure recovery adjusted indexed aortic valve area (AVAi) = energy loss index (ELI), may identify a subgroup of patients with a better outcome.

Methods and results 

Three hundred and seventy-nine patients with low-gradient AS (defined by AVAi ≤ 0.6 cm2/m2 and mean aortic pressure gradient &lt; 40 mmHg) and preserved LVEF ≥50% were studied. Reclassification as moderate AS by ELI was defined as AVAi ≤0.6 cm2/m2 but with an ELI &gt;0.6 cm2/m2. Cardiac events [cardiac mortality and/or need for aortic valve replacement (AVR)] during follow-up were studied. One hundred and forty-eight patients (39%) were reclassified as moderate AS by ELI. Reclassification as moderate AS was independently associated with decreased body surface area, normal flow status, decreased left ventricular mass index, and left atrial volume index (all P &lt; 0.05). After adjustment for variables of prognostic interest, reclassification as moderate AS by ELI was associated with a considerable reduction of risk of cardiac events {adjusted hazard ratio (HR) 0.49 [95% confidence interval (CI) 0.33–0.72]; P &lt; 0.001}, need for AVR [adjusted HR 0.52 (95% CI 0.34–0.81); P = 0.004], and cardiac mortality [adjusted HR 0.46 (95% CI 0.22–0.98); P = 0.044].

Conclusion 

In patients with low-gradient severe AS and preserved LVEF, calculation of ELI permits to reclassify almost 40% of patients as having moderate AS. These reclassified patients have a considerable reduction of the risk of cardiac events during follow-up. Calculation of ELI is useful for decision-making in patients with low-gradient severe AS and preserved ejection fraction.

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.

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.

Modeling of the Instantaneous Transvalvular Pressure Gradient in Aortic Stenosis

The simplified and modified Bernoulli equations break down in estimating the true pressure gradient across the stenotic aortic valve due to their over simplifying assumptions of steady and inviscid conditions as well as the fundamental nature in which aortic valves are different than idealized orifices. Nevertheless, despite having newer models based on time-dependent momentum balance across an orifice, the simplified and modified Bernoulli continue to be the clinical standard because to date, they remain the only models clinically implementable. The objective of this study is to (1) illustrate the fundamental considerations necessary to accurately model the time-dependent instantaneous pressure gradient across a fixed orifice and (2) propose empirical corrections when applying orifice based models to severely stenotic aortic valves. We introduce a general model to predict the time-dependent instantaneous pressure gradient across an orifice that explicitly model the Reynolds number dependence of both the steady and unsteady terms. The accuracy of this general model is assessed with respect to previous models through pulse duplicator experiments on a round orifice model as well as an explanted stenotic surgical aortic valve both with geometric areas of 0.6 cm² (less than 1 cm² which is the threshold for stenosis determination) over cardiac outputs of 3 and 5 L/min and heart rates of 60, 90 and 120 bpm. The model and the raw experimental data corresponding to the orifice showed good agreement over a wide range of cardiac outputs and heart rates (R² exceeding 0.91). The derived average and peak transvalvular pressure gradients also demonstrated good agreement with no significant differences between the respective peaks (p > 0.09). The new model proposed holds promise with its physical and closed form representation of pressure drop, however accurate modeling of the time-variability of the valve area is necessary for the model to be applied on stenotic valves.

Bicuspid Aortic Valve: An Update in Morphology, Genetics, Biomarker, Complications, Imaging Diagnosis and Treatment

The bicuspid aortic valve, a kind of heart disease that comes from parents, has been paid attention around the world. Although most bicuspid aortic valve (BAV) patients will suffer from some complications including aortic stenosis, aortic regurgitation, endocarditis, and heart dysfunction in the late stage of the disease, there is none symptom in the childhood, which restrains us to diagnose and treatment in the onset phase of BAV. Hemodynamic abnormalities induced by the malformations of the valves in BAV patients for a long time will cause BAV-associated aortopathy: including progress aortic dilation, aneurysm, dissection and rupture, cardiac cyst and even sudden death. At present, preventive surgical intervention is the only effective method used in this situation and the diameter of the aorta is the primary reference criterion for surgery. And the treatment effects are always not satisfactory for patients and clinicians. Therefore, we need more methods to evaluate the progression of BAV and the surgery value and the appropriate intervention time by combining basic research with clinical treatment. In this review, advances in morphology, genetic, biomarkers, diagnosis and treatments are summarized, which expects to provide an update about BAV. It is our supreme expectations to provide some evidences for BAV early screening and diagnosis, and in our opinion, personalized surgical strategy is the trend of future BAV treatment.

The role of echocardiography in transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) is an effective and less invasive treatment for the increasing population of individuals with severe aortic stenosis (AS). Echocardiography is crucial in the assessment of AS patients from pre- to post-procedure. Transthoracic echocardiography (TTE) may be used to assess patient suitability for TAVI, as well as evaluate the severity of AS, the aortic valve complex, aortic valve morphology, mitral regurgitation (MR), and left ventricular function. Transesophageal echocardiography (TEE) is usually used as an intra-procedural monitoring tool to provide feedback during the procedure, to assess prosthetic valve function, and to detect complications rapidly before and after balloon aortic valvuloplasty (BAV) or transcatheter heart valve (THV) deployment. In this review, the role of echocardiography in the pre-, intra-, and post-TAVI procedure periods is described in detail.

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

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

Association Between Echocardiography Laboratory Accreditation and the Quality of Imaging and Reporting for Valvular Heart Disease

Background—

It is presumed that echocardiographic laboratory accreditation leads to improved quality, but there are few data. We sought to compare the quality of echocardiographic examinations performed at accredited versus nonaccredited laboratories for the evaluation of valvular heart disease.

Methods and Results—

We enrolled 335 consecutive valvular heart disease subjects who underwent echocardiography at our institution and an external accredited or nonaccredited institution within 6 months. Completeness and quality of echocardiographic reports and images were assessed by investigators blinded to the external laboratory accreditation status and echocardiographic results. Compared with nonaccredited laboratories, accredited sites more frequently reported patient sex (94% versus 78%; P <0.001), height and weight (96% versus 63%; P <0.001), blood pressure (86% versus 39%; P <0.001), left ventricular size (96% versus 83%; P <0.001), right ventricular size (94% versus 80%; P =0.001), and right ventricular function (87% versus 73%; P =0.006). Accredited laboratories had higher rates of complete and diagnostic color (58% versus 35%; P =0.002) and spectral Doppler imaging (45% versus 21%; P <0.0001). Concordance between external and internal grading of external studies was improved when diagnostic quantification was performed (85% versus 69%; P =0.003), and in patients with mitral regurgitation, reproducibility was improved with higher quality color Doppler imaging.

Conclusions—

Accredited echocardiographic laboratories had more complete reporting and better image quality, while echocardiographic quantification and color Doppler image quality were associated with improved concordance in grading valvular heart disease. Future quality improvement initiatives should highlight the importance of high-quality color Doppler imaging and echocardiographic quantification to improve the accuracy, reproducibility, and quality of echocardiographic studies for valvular heart disease.

Feasibility and relevance of right parasternal view for assessing severity and rate of progression of aortic valve stenosis in primary care

BACKGROUND

Right parasternal view (RPV) is important in assessing the severity of aortic stenosis (AS). However, the feasibility and relevance of RPV in primary care is unresolved. Moreover, information regarding the role of RPV in the evaluation of the hemodynamic progression of AS is lacking.

METHODS

Consecutive patients with peak aortic valve velocity (V_max) ≥2.5m/s were prospectively enrolled in a primary care echocardiographic laboratory. Aortic Doppler parameters were evaluated from apical view and RPV.

RESULTS

The total number of enrolled patients was 330 (aged 81±11years, 47% female, left ventricular ejection fraction 64±9%). The RPV was feasible in 275 (83%). V_max and Mean Gradient were significantly higher and aortic valve area was significantly lower from RPV as compared to apical view (p<0.0001 for all). Reclassification of severity towards either moderate or severe AS occurred in 13-26% of patients, according to different criteria, when evaluated from RPV. Among 108 patients (40%) undergoing multiple examinations the rate of progression was lower from the apical approach than from the RPV (0.19±0.20m/s/year vs. 0.24±0.27m/s/year, respectively; p=0.03), and was fast (>0.3m/s/year) in 17 patients (16%) from the apical window vs. 26 patients (24%) from RPV (p<0.0001).

CONCLUSION

Implementing RPV is feasible in primary care and results in a substantial reclassification rate through the entire spectrum of AS severity. Our data also suggest a potential role of Doppler interrogation from multiple windows to improve AS progression assessment.

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

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