Differential Left Ventricular Outflow Tract Remodeling and Dynamics in Aortic Stenosis

Impact of stroke volume assessment by three-dimensional transesophageal echocardiography on the classification of low-gradient aortic stenosis

BACKGROUND

Accurate assessment of flow status is crucial in low-gradient aortic stenosis (AS). However, the clinical implication of three-dimensional transesophageal echocardiography (3DTEE) on flow status evaluation remains unclear. This study aimed to investigate the assessment of flow status using 3D TEE in low-gradient AS patients.

METHODS

We retrospectively reviewed patients diagnosed with low-gradient AS and preserved ejection fraction at our institution between 2019 and 2022. Patients were categorized into low-flow/low-gradient (LF-LG) AS or normal-flow/low-gradient (NF-LG) AS based on two-dimensional transthoracic echocardiography (2DTTE). We compared the left ventricular outflow tract (LVOT) geometry between the two groups and reclassified them using stroke volume index (SVi) obtained by 3DTEE.

RESULTS

Among 173 patients (105 with LF-LG AS and 68 with NF-LG AS), 54 propensity-matched pairs of patients were analyzed. 3DTEE-derived ellipticity index of LVOT was significantly higher in LF-LG AS patients compared to NF-LG AS patients (p = 0.012). We assessed the discordance in flow status classification between SVi2DTTE and SVi3DTEE in both groups using a cutoff value of 35 ml/m2. The LF-LG AS group exhibited a significantly higher discordance rate compared to the NF-LG AS group, with rates of 50% and 2%, respectively. The optimal cutoff values of SVi3DTEE for identifying low flow status, based on 2DTTE-derived cutoff values, were determined to be 43 ml/m2.

CONCLUSIONS

LVOT ellipticity in low-gradient AS patients varies depending on flow status, and this difference contributes to discrepancies between SVi3DTEE and SVi2DTTE, particularly in LF-LG AS patients. Utilizing SVi3DTEE is valuable for accurately assessing flow status.

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.

Balloon-Expandable TAVR Bioprostheses: Area or Perimeter Sizing? A Prospective Pilot Study

Objective. In TAVR, area sizing is used for balloon-expandable (BE) valves, whereas self-expanding valves are sized to annulus perimeter. For BE valves, this seems illogical: these frames force a circular shape even on an ellipsoid annulus. This can potentially lead to relative undersizing when area sizing is being applied. We developed a perimeter-based sizing algorithm to evaluate the safety and feasibility of perimeter sizing for the Myval BE valve. Methods. In this prospective single-center study, 60 patients with severe aortic stenosis treated with the Myval BE valve were included. Perimeter sizing was used with limited oversizing of 3.7% ± 1.3% compared to the annulus perimeter. After TAVR, clinical outcomes were evaluated at 30 days and 1 year. An echocardiographic follow-up took place at 30 days. Results. At 30 days, the need for PPI and stroke occurred in 2% and 3% of the patients, respectively. Moreover, cardiac death and moderate-severe PVL were absent. At 1-year, cardiac death and stroke were observed in 3% and 8% of the patients, respectively. In 33.3% of the patients, a larger valve size was implanted compared to the valve size calculated by area sizing. Conclusions. Perimeter sizing with the Myval BE valve leads to substantial use of larger valve sizes and favorable clinical outcomes, with low PPI and the absence of significant PVL. A randomized controlled trial is being planned to prove the superiority of this alternative sizing method.

Orifice areas of balloon-expandable transcatheter heart valves: a three-dimensional transesophageal echocardiography study

INTRODUCTION

Accurate expected effective orifice area (EOA) values for balloon-expandable (BE) transcatheter heart valves (THV) are crucial for preventing patient prosthesis mismatch (PPM) and assessment of THV function. Currently published reference EOAs, however, are based on transthoracic echocardiography (TTE) which may be subject to left ventricular outflow tract diameter underestimation and/or suboptimal THV Doppler interrogation. The objective of this study was to establish reference EOA values for BE THVs based on Doppler and three-dimensional (3D) transesophageal echocardiography (TEE).

METHODS

We retrospectively reviewed 212 intra-procedural TEEs performed during BE THV implantation with optimal post-implant Doppler and 3D imaging. We compared continuity equation-derived EOAs to geometric orifice areas by 3D-planimetry (GOA_3D). Performance indices (i.e., EOA normalized to valve size) and PPM rates were determined. TTE-based EOAs performed within 30 days were also calculated in a subset of 170 patients.

RESULTS

The average EOA for all BE THV valves (77% Sapien 3) was 2.3 cm² ± 0.5, while the average EOA was 1.6 ± 0.2 cm² for 20 mm, 2.0 ± 0.2 cm² for 23 mm, 2.5 ± 0.3 cm² for 26 mm and 3.0 ± 0.3 cm² for 29 mm THV size (p<0.001). Bland-Altman analysis demonstrated very good agreement between EOA and GOA_3D (bias -0.04 ± 0.15 cm²). There was a strong correlation between annular area and TEE-based EOA (R=0.84) and GOA_3D (R=0.87). The mean performance index was 47 ± 5% and was similar for all THV sizes (p=0.21). EOAs based on TTE were smaller compared to TEE, while the correlation with annular area (R=0.67) and agreement with GOA_3D (bias -0.26 ± 0.43 cm²) was not as strong. The overall PPM rate was 2% in the TEE cohort and 12% in the TTE cohort.

CONCLUSIONS

Effective orifice areas for BE THVs based on intra-procedural Doppler and 3D-TEE suggest that previously published TTE-based reference values for EOA are underestimated while PPM rates may be overestimated. Our findings have important clinical implications for pre-implant decision making and for the evaluation of THV hemodynamics and function during follow-up.

Impact of sigmoid septum on periprocedural outcomes following transcatheter aortic valve implantation using current-generation valves

The role of sigmoid septum (SS) observed using preprocedural transthoracic echocardiography (TTE) in patients undergoing transcatheter aortic valve implantation (TAVI) remains unknown. This study aimed to compare clinical outcomes of TAVI using the current-generation transcatheter heart valves in patients with and without SS. We divided 140 consecutive patients, excluding four patients who underwent pacemaker implantation before TAVI, into two groups (those with and without SS) and compared the periprocedural outcomes, including new pacemaker implantation, within 30 days post-TAVI. Thirty-five patients (25%; 32 female patients) had SS before TAVI. The body surface area and aortic annulus area measured using computed tomography were significantly smaller in patients with SS than in those without SS (1.40 m² vs. 1.48 m², P = 0.03; and 372 mm² vs. 409 mm², P < 0.01; respectively). Device success was achieved in all patients with SS. Postprocedural TTE on 30 days post-TAVI showed no significant differences in the valvular hemodynamics between patients with and without SS. No severe prosthesis-patient mismatch was noted on TTE, although the transcatheter heart valve size tended to be smaller in patients with SS. Within 30 days of the TAVI, three (8.6%) and eight (7.6%) patients with and without SS, respectively, had new pacemaker implantation (P = 0.86). The presence of SS was not associated with periprocedural outcomes following TAVI in patients without pre-existing pacemakers. No specific assessment or treatment strategy is required for the TAVI in patients with SS using the current-generation devices.

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.

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.

The Left Ventricular Outflow Tract Changes in Size and Shape From Pre- to Post-Cardiopulmonary Bypass: Three-Dimensional Transesophageal Echocardiography

OBJECTIVES

To compare two-dimensional (2D) and 3D imaging of the left ventricular outflow tract (LVOT) and to evaluate geometric changes pre- to post-cardiopulmonary bypass (CPB).

DESIGN

Retrospective review of intraoperative transesophageal echocardiographic examinations.

SETTING

Single academic medical center.

PARTICIPANTS

The study comprised 69 cardiac surgical patients-27 with aortic valve stenosis (AS) and 42 without AS.

INTERVENTIONS

Two-dimensional and 3D analysis of the LVOT pre- and post-CPB.

MEASUREMENTS AND MAIN RESULTS

Pre- and post-CPB 2D assessment of LVOT diameter (2D LVOTd) was compared with 3D analysis of the minor (3D LVOTd-min) and major diameters. LVOT areas (LVOTa) were calculated using LVOTd to yield 2D LVOTa and 3D LVOTa-min. These were compared with LVOTa measured by planimetry (3D LVOTa-plan). An ellipticity ratio (ER) (ER = 3D minor/major axes) was calculated. The 2D LVOTd was larger than the 3D LVOTd-min before (2.12 v 2.02 cm respectively (resp); p < 0.001) and after (1.96 v 1.85 cm resp; p = 0.04) CPB. Compared with pre-CPB, there were significant decreases in the 2D LVOTd (p = 0.003) and the 3D LVOTd-min (p < 0.001) post-CPB. Ellipticity increased after CPB (ER 0.80 v 0.75; p = 0.004), and the 2D LVOTa was larger than the 3D LVOTa-min before CPB (3.60 cm²v 3.28 cm²; p < 0.001) and less so after CPB (3.11 cm²v 2.79 cm²; p = 0.053). Compared with pre-CPB, all LVOTa measurements decreased significantly after CPB (p < 0.001). The 3D LVOTa-plan decreased after CPB by approximately 10% (4.05 cm²v 3.61 cm²; p < 0.001). The 2D LVOTa and 3D LVOTa-min underestimated the 3D LVOTa-plan before and after CPB (p < 0.001) by 11% to 14% and 19% to 23%, respectively. When compared with non-AS patients, patients with AS had a smaller LVOTa pre- and post-CPB (p < 0.05).

CONCLUSIONS

The LVOT is smaller and more elliptical after CPB. Patients with AS have a smaller LVOT compared with non-AS patients. LVOTa calculated using LVOTd underestimates the 3D LVOTa-plan by as much as 23% depending on patient type and timing of measurement. Accurate assessment of the LVOT requires 3D imaging.

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

Background

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

Methods

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

Results

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

Conclusions

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

Aortic valve area calculation using 3D transesophageal echocardiography: Implications for aortic stenosis severity grading

AIMS

Aortic stenosis (AS) grading by 2D-transthoracic echocardiography (2D-TTE) aortic valve area (AVA) calculation is limited by left ventricular outflow tract (LVOT) area underestimation. The combination of Doppler parameters with 3D LVOT area obtained by multidetector computed tomography (MDCT) can improve AS grading, reconciling discordant 2D-TTE findings. This study aimed to systematically evaluate the role of 3D-transesophageal echocardiography (3D-TEE) in AS grading using MDCT as reference standard.

METHODS AND RESULTS

288 patients (81 ± 6.3 years, 52.4% female) with symptomatic AS underwent 2D-TTE, 3D-TEE, and MDCT for transcatheter aortic valve implantation. Doppler parameters were combined with 3D LVOT areas measured by manual and semi-automated software 3D-TEE and by MDCT to calculate AVA, reassessing AS severity. Both 3D-TEE modalities demonstrated good correlation with MDCT, with excellent intra-observer and inter-observer variability. Compared to MDCT, 3D-TEE measurements significantly underestimated AVA (P_ANOVA  < .0001), although the difference was clinically acceptable. Compared to 2D-TTE, 3D-TEE manual and semi-automated software reclassified severe AS in 21.9% and 25.2% of cases, respectively (P < .0001), overcame grading parameters discordance in more than 40% of cases in patients with low-gradient AS (P < .0001) and reduced the proportion of low-flow states in nearly 75% of cases when combined to stroke volume index assessment (P < .0001). 3D-TEE imaging modalities showed a reduction in the proportion of patients with low-gradient and pathological AVA as defined by 2D-TTE, and improved AVA and mean pressure gradient agreement with current guidelines cutoff values.

CONCLUSION

3D-TEE AVA calculation is a reliable tool for AS grading with excellent reproducibility and good correlation with MDCT measurements.

Impact of Arterial Blood Pressure on Ultrasound Hemodynamic Assessment of Aortic Valve Stenosis Severity

BACKGROUND

Aortic stenosis (AS) severity assessment is based on several indices. Aortic valve area (AVA) is subject to inaccuracies inherent to the measurement method, while velocities and gradients depend on hemodynamic status. There is controversy as to whether blood pressure directly affects common indices of AS severity.

OBJECTIVES

The study objective was to assess the effect of systolic blood pressure (SBP) variation on AS indices, in a clinical setting.

METHODS

A prospective, single-center study included 100 patients with at least moderately severe AS with preserved left ventricle ejection fraction. Patients underwent ultrasound examination during which AS severity indices were collected, with three hemodynamic conditions: (1) low SBP: <120 mm Hg; (2) intermediate SBP: between 120 and 150 mm Hg; (3) high SBP: ≥150 mm Hg. For each patient, SBP profiles were obtained by injection of isosorbide dinitrate or phenylephrine.

RESULTS

At baseline state, 59% presented a mean gradient (G_mean) ≥ 40 mm Hg, 44% a peak aortic jet velocity (V_peak) ≥4 m/sec, 66% a dimensionless index (DI) ≤0.25, and 87% an indexed AVA (AVAi) ≤ 0.6 cm²/m². Compared with intermediate and low SBP, high SBP induced a significant decrease in G_mean (39 ± 12 vs 43 ± 12 and 47 ± 12 mm Hg, respectively; P < .05) and in V_peak (3.8 ± 0.6 vs 4.0 ± 0.6 and 4.2 ± 0.6 mm Hg; P < .05). Compared with the baseline measures, in 16% of patients with an initial G_mean< 40 mm Hg, gradient rose above 40 mm Hg after optimization of the afterload (low SBP; P < .05). Conversely, DI and AVAi did not vary with changes in hemodynamic conditions. Flow rate, not stroke volume was found to impact G_mean and V_peak but not AVA and DI (P < .05).

CONCLUSIONS

Hemodynamic conditions may affect the AS ultrasound assessment. High SBP, or afterload, leads to an underestimation of AS severity when based on gradients and velocities. Systolic blood pressure monitoring and control are crucial during AS ultrasound assessment.

Estimation of Stroke Volume and Aortic Valve Area in Patients with Aortic Stenosis: A Comparison of Echocardiography versus Cardiovascular Magnetic Resonance

BACKGROUND

In aortic stenosis, accurate measurement of left ventricular stroke volume (SV) is essential for the calculation of aortic valve area (AVA) and the assessment of flow status. Current American Society of Echocardiography and European Association of Cardiovascular Imaging guidelines suggest that measurements of left ventricular outflow tract diameter (LVOTd) at different levels (at the annulus vs 5 or 10 mm below) yield similar measures of SV and AVA. The aim of this study was to assess the effect of the location of LVOTd measurement on the accuracy of SV and AVA measured on transthoracic echocardiography (TTE) compared with cardiovascular magnetic resonance (CMR).

METHODS

One hundred six patients with aortic stenosis underwent both TTE and CMR. SV was estimated on TTE using the continuity equation with LVOTd measurements at four locations: at the annulus and 2, 5, and 10 mm below annulus. SV was also determined on CMR using phase contrast acquired in the aorta (SV_CMR-PC), and a hybrid AVA_CMR-PC was calculated by dividing SV_CMR-PC by the transthoracic echocardiographic Doppler aortic velocity-time integral. Comparison between methods was made using Bland-Altman analysis.

RESULTS

Compared with the referent method of phase-contrast CMR for the estimation of SV_CMR-PC and AVA_CMR-PC (SV_CMR-PC 83 ± 16 mL, AVA_CMR-PC 1.27 ± 0.35 cm²), the best agreement was obtained by measuring LVOTd at the annulus or 2 mm below (P = NS), whereas measuring 5 and 10 mm below the annulus resulted in significant underestimation of SV and AVA by up to 15.9 ± 17.3 mL and 0.24 ± 0.28 cm², respectively (P < .01 for all). Accuracy for classification of low flow was best at the annulus (86%) and 2 mm below (82%), whereas measuring 5 and 10 mm below the annulus significantly underperformed (69% and 61%, respectively, P < .001).

CONCLUSIONS

Measuring LVOTd at the annulus or very close to it provides the most accurate measures of SV and AVA, whereas measuring LVOTd 5 or 10 mm below significantly underestimates these parameters and leads to significant overestimation of the severity of aortic stenosis and prevalence of low-flow status.

Impact of anatomical variations of the left ventricular outflow tract on stroke volume calculation by Doppler echocardiography in aortic stenosis

BACKGROUND

Accurate calculation of stroke volume (SV) by Doppler echocardiography is important for the assessment of aortic stenosis (AS), which may be impacted by anatomical variations of left ventricular outflow tract (LVOT).

METHODS

Patients with AS (n = 64) were studied using computed tomography (CT) and transthoracic echocardiography (TTE). Anatomical variations of LVOT areas were measured at (a) the aortic annulus (A_a ); (b) 5 mm (A₅ ); and (c) 10 mm below the annulus (A₁₀ ) by CT. LVOT diameters were also measured by 2D TTE at these three levels for calculation of LVOT areas. Stroke volumes (SV) were calculated using continuity equation. The impacts of anatomical variations of LVOT on SV calculation were evaluated.

RESULTS

Anatomical LVOT area increased from A_a to A₁₀ (5.0 ± 0.9 cm² vs 5.8 ± 1.9 cm² , P < .01). Differences between TTE-calculated LVOT areas and anatomical areas were most significant at A₁₀ due to elongation of mediolateral diameters with variable changes in anteroposterior diameters (5.8 ± 1.9 cm² vs 3.4 ± 1.1 cm² , P < .001). Although mean calculated SV by TTE was not significant at different LVOT levels (A_a 69 ± 22 mL, vs A₅ 66 ± 21 mL, vs A₁₀ 66 ± 28 ± 22 mL, P > .05), the most significant variations in individuals were at A₁₀ levels (ΔSV: 8.2 ± 6.4 mL, 12 ± 9%).

CONCLUSION

Variations of LVOT anatomy in individuals with AS significantly impact the SV calculated by Doppler echocardiography. These features should be taken into account for AS diagnosis and a clinical decision-making for intervention.

Direct Planimetry of Left Ventricular Outflow Tract Area by Simultaneous Biplane Imaging: Challenging the Need for a Circular Assumption of the Left Ventricular Outflow Tract in the Assessment of Aortic Stenosis

BACKGROUND

Evaluation of aortic stenosis (AS) requires calculation of aortic valve area (AVA), which relies on the assumption of a circular-shaped left ventricular outflow tract (LVOT). However, the LVOT is often elliptical, and the circular assumption underestimates the true LVOT area (LVOTA). Biplane imaging using transthoracic echocardiography allows direct planimetry of LVOTA. The aim of this study was to assess the feasibility of obtaining LVOTA using this technique and its impact on the discordance between AVA and gradient criteria in AS grading.

METHODS

We prospectively studied 134 patients (median age, 80 years; interquartile range, 73-87 years; 39% women) with AS, including 82 (61%) with severe AS and 52 (39%) with mild or moderate AS. LVOTA was traced using direct planimetry (LVOTA_biplane) and compared with LVOTA calculated using the circular assumption (LVOTA_circ). In a subset of patients who underwent cardiac computed tomography, direct planimetry of LVOTA was used as a reference standard.

RESULTS

LVOTA_biplane was significantly larger than LVOTA_circ (4.20 cm² [interquartile range, 3.66-4.90 cm²] vs 3.73 cm² [interquartile range, 3.14-4.15 cm²], P < .001). Among 30 patients who underwent cardiac computed tomography, LVOTA_biplane had better agreement with LVOTA by direct planimetry than LVOTA_circ (mean bias, -0.45 ± 0.63 vs -1.02 ± 0.63 cm²; P < .0001). Of 82 patients with severe AS (AVA ≤ 1 cm² using LVOTA_circ), 40 (49%) had discordant mean gradient (<40 mm Hg). By using LVOTA_biplane, patients with discordant AVA and mean gradient decreased from 49% to 27% (P = .004), and 29% of patients with severe AS were reclassified with moderate AS, with the highest percentage of reclassification in the group with low-gradient AS with preserved left ventricular ejection fraction.

CONCLUSIONS

Direct planimetry using biplane imaging avoids the inherent underestimation of LVOTA using the circular assumption. LVOTA obtained by biplane planimetry can lead to better concordance between AVA and mean gradient and classification of AS severity.

Measurement errors in serial echocardiographic assessments of aortic valve stenosis severity

Transthoracic echocardiography (TTE) evaluation of aortic stenosis (AS) is routinely performed using the continuity equation. Inaccurate measurements of the left ventricular (LV) outflow tract (LVOT) diameter are considered the most common source of error in AS grading. We hypothesized that inconsistency in LVOT velocity time integral (VTI) is an under-recognized cause of AS assessment error. We sought to determine which parameters contribute most towards inconsistencies in AS grading by studying the prevalence of different errors in a historic cohort. We identified patients with mild to severe AS with multiple studies from our database from 1994 to 2018 (n = 988 patients, 2859 studies). Errors were defined when: (1) LVOT diameter changed by > 2 mm, (2) LVOT VTI changed by > 15% without change in LV function from the initial TTE, (3) aortic valve (AV) maximum velocity (Vmax), mean pressure gradient (ΔP) or AV VTI decreased by > 15% without change in LV function from prior study. The most common error was the LVOT VTI measurement with 22% prevalence. LVOT diameter, AV VTI, AV Vmax and AV ΔP measurement caused errors in < 7% studies. Patients with normal LV function and more severe AS were more likely to have LVOT VTI errors (P < 0.05). LVOT VTI is a frequent, under-recognized source of error in assessing AS. Greater attention should be directed toward the proper positioning of the pulsed Doppler sample volume, particularly in patients with higher grades of AS and normal systolic function, to ensure accurate and reproducible assessment of AS.

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.

The Impact of Basal Septal Hypertrophy on Outcomes after Transcatheter Aortic Valve Replacement

BACKGROUND

The role of basal septal hypertrophy (BSH) on preprocedural transthoracic echocardiography in transcatheter aortic valve replacement (TAVR) is unknown.

METHODS

Medical charts and preprocedural transthoracic echocardiograms of 378 patients who underwent TAVR were examined. The association between BSH and the primary composite outcome of valve pop-out, recapture, embolization, aborted procedure, conversion to open procedure, new conduction disturbance, or need for permanent pacemaker ≤30 days after TAVR was evaluated. Patients with preexisting pacemakers were excluded. Sensitivity analyses were performed varying the definition of BSH.

RESULTS

Of 296 TAVR patients (78.3%) with interpretable images, 55 (18.6%) had BSH at a median of 40 days (interquartile range, 19-62 days) before TAVR. Age and sex were similar among those with and without BSH. BSH patients received postdilation more frequently (BSH+ vs BSH-: 41.8% vs 29.9%, P = .04). A total of 50 individuals (16.9%) received pacemakers within 30 days, and 128 (43.2%) developed conduction disturbances (with left bundle branch block most common), without differences between groups. BSH was unrelated to the primary outcome on multivariate analysis (adjusted odds ratio BSH+ vs BSH-, 0.94; 95% CI, 0.42-2.11; P = .88).

CONCLUSIONS

In this convenience sample of TAVR recipients at a large academic medical center, patients with BSH were more likely to receive postdilation. BSH was not associated with procedural or conduction outcomes after TAVR in patients without preexisting pacemakers.

Assessment of aortic valve tract dynamics using automatic tracking of 3D transesophageal echocardiographic images

The assessment of aortic valve (AV) morphology is paramount for planning transcatheter AV implantation (TAVI). Nowadays, pre-TAVI sizing is routinely performed at one cardiac phase only, usually at mid-systole. Nonetheless, the AV is a dynamic structure that undergoes changes in size and shape throughout the cardiac cycle, which may be relevant for prosthesis selection. Thus, the aim of this study was to present and evaluate a novel software tool enabling the automatic sizing of the AV dynamically in three-dimensional (3D) transesophageal echocardiography (TEE) images. Forty-two patients who underwent preoperative 3D-TEE images were retrospectively analyzed using the software. Dynamic measurements were automatically extracted at four levels, including the aortic annulus. These measures were used to assess the software's ability to accurately and reproducibly quantify the conformational changes of the aortic root and were validated against automated sizing measurements independently extracted at distinct time points. The software extracted physiological dynamic measurements in less than 2 min, that were shown to be accurate (error 2.2 ± 26.3 mm² and 0.0 ± 2.53 mm for annular area and perimeter, respectively) and highly reproducible (0.85 ± 6.18 and 0.65 ± 7.90 mm² of intra- and interobserver variability, respectively, in annular area). Using the maximum or minimum measured values rather than mid-systolic ones for device sizing resulted in a potential change of recommended size in 7% and 60% of the cases, respectively. The presented software tool allows a fast, automatic and reproducible dynamic assessment of the AV morphology from 3D-TEE images, with the extracted measures influencing the device selection depending on the cardiac moment used to perform its sizing. This novel tool may thus ease and potentially increase the observer's confidence during prosthesis' size selection at the preoperative TAVI planning.

Staging classification of aortic stenosis based on the extent of cardiac damage

Aims

In patients with aortic stenosis (AS), risk stratification for aortic valve replacement (AVR) relies mainly on valve-related factors, symptoms and co-morbidities. We sought to evaluate the prognostic impact of a newly-defined staging classification characterizing the extent of extravalvular (extra-aortic valve) cardiac damage among patients with severe AS undergoing AVR.

Methods and results

Patients with severe AS from the PARTNER 2 trials were pooled and classified according to the presence or absence of cardiac damage as detected by echocardiography prior to AVR: no extravalvular cardiac damage (Stage 0), left ventricular damage (Stage 1), left atrial or mitral valve damage (Stage 2), pulmonary vasculature or tricuspid valve damage (Stage 3), or right ventricular damage (Stage 4). One-year outcomes were compared using Kaplan–Meier techniques and multivariable Cox proportional hazards models were used to identify 1-year predictors of mortality. In 1661 patients with sufficient echocardiographic data to allow staging, 47 (2.8%) patients were classified as Stage 0, 212 (12.8%) as Stage 1, 844 (50.8%) as Stage 2, 413 (24.9%) as Stage 3, and 145 (8.7%) as Stage 4. One-year mortality was 4.4% in Stage 0, 9.2% in Stage 1, 14.4% in Stage 2, 21.3% in Stage 3, and 24.5% in Stage 4 (P_trend < 0.0001). The extent of cardiac damage was independently associated with increased mortality after AVR (HR 1.46 per each increment in stage, 95% confidence interval 1.27–1.67, P < 0.0001).

Conclusion

This newly described staging classification objectively characterizes the extent of cardiac damage associated with AS and has important prognostic implications for clinical outcomes after AVR.

Geometry of the left ventricular outflow tract assessed by 3D TEE in patients with aortic stenosis: impact of upper septal hypertrophy on measurements of Doppler-derived left ventricular stroke volume

BACKGROUND

It is unclear how upper septal hypertrophy (USH) affects Doppler-derived left ventricular stroke volume (SV) in patients with AS. The aims of this study were to: (1) validate the accuracy of 3D transesophageal echocardiography (TEE) measurements of the left ventricular outflow tract (LVOT), (2) evaluate the differences in LVOT geometry between AS patients with and without USH, and (3) assess the impact of USH on measurement of SV.

METHODS

In protocol 1, both 3D TEE and multi-detector computed tomography were performed in 20 patients with AS [aortic valve area (AVA) ≤ 1.5 cm²]. Multiplanar reconstruction was used to measure the LVOT short and long diameters in four parts from the tip of the septum to the annulus. In protocol 2, the same 3D TEE measurements were performed in AS patients (AVA ≤ 1.5 cm², n = 129) and controls (n = 30). We also performed 2D and 3D transthoracic echocardiography in all patients.

RESULTS

In protocol 1, excellent correlations of LVOT parameters were found between the two modalities. In protocol 2, the USH group had smaller LVOT short and long diameters than the non-USH group. Although no differences in mean pressure gradient, or SV calculated with the 3D method existed between the two groups, the USH group had greater SV calculated with the Doppler method (73 ± 15 vs. 66 ± 15 ml) and aortic valve area (0.89 ± 0.26 vs. 0.73 ± 0.24 cm²) than the non-USH group.

CONCLUSIONS

3D TEE can provide a precise assessment of the LVOT in AS. USH affects the LVOT geometry in patients with AS, which might lead to inaccurate assessments of disease severity.

Take home messages with cases from focused update on echocardiographic assessment of aortic stenosis

Echocardiography plays an important role in the assessment of valvular aortic stenosis. Updated recommendations focusing on a stepwise approach to evaluating aortic stenosis have recently been published by the European Association of Cardiovascular Imaging and the American Society of Echocardiography. This review uses illustrative cases to demonstrate technical aspects of aortic stenosis assessment and use of the new proposed classification scheme for aortic stenosis. Key points from the updated recommendations reviewed in this paper are: (1) technical considerations and sources of error in measurement of peak velocity, mean aortic valve gradient and aortic valve area by continuity equation. (2) Application of flow status using indexed left ventricular stroke volume to distinguish patients with low gradients and a low calculated aortic valve area. (3) Use of low-dose dobutamine stress echocardiography in patients with low ejection fraction. (4) Application of the new classification scheme and review of algorithm use for echocardiographic evaluation of severe aortic stenosis. Improved understanding of how to handle unmatched variables and adopting an integrated approach to determine severity is central to guiding the clinician’s management of aortic stenosis.

The Pivotal Role of Imaging in TAVR Procedures

PURPOSE OF REVIEW

Transcatheter aortic valve replacement (TAVR) is underpinned by an array of imaging techniques designed to not only select an appropriately sized implant but also to identify potential obstacles to procedural success. This review presents currently important aspects of TAVR imaging, describing the salient features of each modality as well as recent developments in the field.

RECENT FINDINGS

The latest data on TAVR outcomes reflects the increasing experience of operators and the significant role of pre-procedural imaging. Debate continues as to which modality sizes the aortic annulus most accurately, 3D transoesophageal echocardiography (TEE) or MDCT, as well as to whether the merits of real-time peri-procedural 3D imaging guidance outweigh the possible adverse consequences of general anaesthesia which is requisite for intraprocedural 3D TEE. TAVR is now largely based on pre-acquired roadmaps of the truncal vasculature and intense pre-procedural planning. TEE and Multi-detector computed tomography (MDCT) have been shown to perform similarly in annulus sizing. However, given the complexity of many TAVR patients and the importance of identifying the most suitable pathway to the valve as well as any potentially confounding other structural or functional heart disease, both modalities remain relevant in current TAVR.

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

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

3D and 4D Ultrasound: Current Progress and Future Perspectives

PURPOSE OF REVIEW

Three-dimensional (3D) echocardiography (3DE) and 4-dimensional echocardiography (4DE), also known as real-time (RT) 3DE (RT3DE), are rapidly emerging technologies which have made significant impact in the clinical arena over the years. This review will discuss the recent applications of 3DE in diagnosing and treating different types of cardiovascular disease.

RECENT FINDINGS

Recent studies using 3DE expanded on prior findings and introduced additional applications to different cardiac conditions. Some studies have used 3D parameters to prognosticate long-term outcomes. Numerous innovative software designs including fully automated algorithms have been introduced to better evaluate valvular heart disease and cardiac function.

SUMMARY

With further evolution of 3DE technologies, this imaging modality will emerge as a powerful tool and likely become the imaging modality of choice in the diagnosis and management of various cardiac disorders.

Stress Testing in Asymptomatic Aortic Stenosis

Aortic stenosis is 1 of the most common heart valve diseases among adults. When symptoms develop, prognosis is poor, and current guidelines recommend prompt aortic valve replacement. Depending of the severity of the aortic stenosis and the presence of concomitant heart disease and medical comorbidities, stress testing represents a reasonable strategy to help better risk stratify asymptomatic patients. The present report provides a comprehensive review of the current available data on stress testing in aortic stenosis and subsequently summarizes its potential for guiding the optimal timing of aortic valve replacement.

Imaging for planning of transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) has proven to be the standard of care for patients with prohibitive and high operative risk; today, it is considered a reasonable alternative to surgical aortic valve replacement in intermediate-risk patients. As indications for TAVI move toward patients at lower risk, safety aspects are becoming even more important. Furthermore, adequate patient selection is key for predictable procedural success with minimal complications, translating into an optimal clinical outcome. Decisions on valve type and size as well as on the access route are based on multimodality imaging including echocardiography, multislice computed tomography, and cardiac catheterization with peripheral angiography. This combination of multiple imaging modalities provides the best picture of a patient's anatomical and physiological suitability for the TAVI procedure. Yet, the reliability of preprocedural imaging is influenced by the quality of the images, which should be as high as possible, and both image acquisition and interpretation should be performed in a standardized manner. This article provides a concise overview of standardized multimodality imaging for the preprocedural planning and assessment of patients undergoing TAVI.

Automated and Manual Measurements of the Aortic Annulus with ECG-Gated Cardiac CT Angiography Prior to Transcatheter Aortic Valve Replacement: Comparison with 3D-Transesophageal Echocardiography

RATIONALE AND OBJECTIVES

Multimodality evaluation of the aortic annulus is generally advocated to plan for transcatheter aortic valve replacement (TAVR). We compared aortic annular measurements by cardiac computed tomography angiography (cCTA) to three-dimensional transesophageal echocardiography (3D-TEE), and also evaluated the use of semi-automated software for cCTA annular measurements.

MATERIALS AND METHODS

A retrospective cohort of 74 patients underwent 3D-TEE and electrocardiogram-gated cCTA of the heart within 30 days for TAVR planning. 3D-TEE measurements were obtained during mid-systole; cCTA measurements were obtained during late-systole (40% of R-R interval) and mid-diastole (80% of R-R interval). Annular area was measured independently by manual planimetry and with semi-automated software.

RESULTS

cCTA measurements in systole and diastole were highly correlated for short-axis diameter (r = 0.91), long-axis diameter (r = 0.92), and annular area (r = 0.96), although systolic measurements were significantly larger (P < 0.001), most notably for the short-axis diameter. Good correlation was observed between 3D-TEE and cCTA for short-axis diameter (r = 0.84-0.90), long-axis diameter (r = 0.77-0.79), and annular area (r = 0.89-0.90). As compared to 3D-TEE, annular area is overmeasured by 28 mm² on systolic phase cCTA (P < 0.008), but nearly identical with 3D-TEE on diastolic phase cCTA. Semi-automated and manual cCTA annulus measurements were highly correlated in systole (r = 0.94) and diastole (r = 0.93), although the semi-automated annular area measured 11-30 mm² greater than manual planimetry. Of note, the 95% limits of agreement in our Bland-Altman analysis suggest that the variability in annular area estimates for individual patients between cCTA and 3D-TEE (-100.9 to 99.6 mm²), as well as the variability between manual and automated measurements with cCTA (-105.9 to 45.2 mm²), may be sufficient to alter size selection for an aortic prosthesis.

CONCLUSIONS

Although all cCTA measurements are highly correlated with measurements by 3D-TEE, diastolic phase cCTA measurements tend to be closer to standard mid-systolic 3D-TEE measurements. Semi-automated measurement of the aortic annulus with cCTA is highly correlated with manual planimetry. Nonetheless, annular contours derived by semi-automated software should be visually inspected, as the variability in area estimates for individual cases between manual and automated measurements may alter the sizing of an aortic prosthesis.

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.

Misconceptions and Facts About Aortic Stenosis

Aortic stenosis is the most common valvular heart disease leading to intervention, and it is typically a disease of the elderly. Recent clinical advances have expanded the role of transcatheter aortic valve intervention in patients with severe aortic stenosis, making aortic valve intervention feasible and effective even in patients at intermediate, high, and prohibitive surgical risk. With the rapid advances in treatment, proper diagnosis becomes crucial for a wide range of patients with aortic stenosis: from "concordant" high-gradient aortic stenosis to "discordant" low-gradient aortic stenosis. The latter group commonly presents a clinical challenge requiring thoughtful and comprehensive evaluation to determine eligibility for aortic valve intervention. Providers at all levels should be familiar with basic diagnostic caveats and misconceptions when evaluating patients with possible aortic stenosis.

3D transoesophageal echocardiography in the TAVI sizing arena: should we do it and how do we do it?

Transcatheter aortic valve implantation (TAVI) was initially proven as an alternative to valve replacement therapy in those beyond established risk thresholds for conventional surgery. With time the technique has been methodically refined and offered to a progressively lower risk cohort, and with this evolution has come that of the significant imaging requirements of valve implantation. This review discusses the role of transoesophageal echocardiography (TOE) in the current TAVI arena, aligning it with that of cardiac computed tomography, and outlining how TOE can be used most effectively both prior to and during TAVI in order to optimise outcomes.

[Imaging in structural heart disease : Impact on interventional therapy]

For the treatment of structural heart disease, current options in the catheterization laboratory include MitraClip® implantation for treating severe mitral regurgitation, transcatheter aortic valve implantation (TAVI), closure of a patent foramen ovale (PFO) and occlusion of the left atrial appendage (LAA). These treatment options are based on a precise diagnosis provided by modern cardiac imaging, which is indispensable for treatment recommendations. Its importance for supporting the invasive procedures in the catheterization laboratory is less well known. Due to enhanced soft tissue characterization, it complements fluoroscopy and invasive angiography and thus enormously improves the safety of the procedures. In addition, it allows individualized follow-up care. The current article gives an overview of the clinically most frequently used procedures.

Reliability of Aortic Stenosis Severity Classified by 3-Dimensional Echocardiography in the Prediction of Cardiovascular Events

The estimation of aortic valve area (AVA) by Doppler echocardiography-derived left ventricular stroke volume (LVSV) remains controversial. We hypothesized that AVA estimated from directly measured LVSV by 3-dimensional echocardiography (3DE) on the continuity equation might be more accurate in classifying aortic stenosis (AS) severity. We retrospectively enrolled 265 patients with moderate-to-severe AS with preserved ejection fraction. Indexed AVA (iAVA) was calculated using LVSV derived by 2D Doppler (iAVADop), Simpson's method (iAVASimp), and 3DE (iAVA3D). During a median follow-up period of 397 days (interquartile range 197 to 706 days), 135 patients experienced the composite end point (cardiac death 9%, aortic valve replacement 24%, and cardiovascular event 27%). Estimated iAVA3D and iAVASimp were significantly smaller than iAVADop and moderately correlated with peak aortic jet velocity. Upper septal hypertrophy was a major cause of discrepancy between iAVADop and iAVA3D methods. Based on the optimal cut-off point of iAVA for predicting peak aortic jet velocity >4.0 m/s, 141 patients (53%) were classified as severe AS and 124 patients (47%) as moderate AS by iAVADop. Indexed AVA3D classified 118 patients (45%) as severe and 147 patients (55%) as moderate AS. Of the 124 patients with moderate AS by iAVADop, 22 patients (18%) were reclassified as severe AS by iAVA3D and showed poor prognosis (hazard ratio 2.7, 95% CI 1.4 to 5.0; p = 0.001). In conclusion, 3DE might be superior in classifying patients with AS compared with Doppler method, particularly in patients with upper septal hypertrophy.

The role of TTE in assessment of the patient before and following TAVI for AS

Transcatheter aortic valve implantation is now accepted as a standard mode of treatment for an increasingly large population of patients with severe aortic stenosis. With the availability of this technique, echocardiographers need to be familiar with the imaging characteristics that can help to identify which patients are best suited to conventional surgery or transcatheter aortic valve implantation, and what parameters need to be measured. This review highlights the major features that should be assessed during transthoracic echocardiography before presentation of the patient to the 'Heart Team'. In addition, this review summarises the aspects to be considered on echocardiography during follow-up assessment after successful implantation of a transcatheter aortic valve.

Natural History, Diagnostic Approaches, and Therapeutic Strategies for Patients With Asymptomatic Severe Aortic Stenosis

Aortic stenosis (AS) is one of the most common valvular diseases encountered in clinical practice. Current guidelines recommend aortic valve replacement (AVR) when the aortic valve is severely stenotic and the patient is symptomatic; however, a substantial proportion of patients with severe AS are asymptomatic at the time of first diagnosis. Although specific morphological valve features, exercise testing, stress imaging, and biomarkers can help to identify patients with asymptomatic severe AS who may benefit from early AVR, the optimal management of these patients remains uncertain and controversial. The current report presents a comprehensive review of the natural history and the diagnostic evaluation of asymptomatic patients with severe AS, and is followed by a meta-analysis from reported studies comparing an early AVR strategy to active surveillance, with an emphasis on the level of evidence substantiating the current guideline recommendations. Finally, perspectives on directions for future investigation are discussed.