Left Ventricular Outflow Tract Area Research Articles

Two- or 3-Dimensional Echocardiography–Derived Cardiac Output Cannot Replace the Pulmonary Artery Catheter in Cardiac Surgery

Three-dimensional (3D) transesophageal echocardiography (TEE) has been shown to be more accurate than 2D TEE for the evaluation of the left ventricular outflow tract area. The aim of the present study was to compare the agreement of 3D echocardiography-derived cardiac output (CO) with thermodilution-derived CO (TDCO) before and after cardiopulmonary bypass (CPB). This was a prospective observational study of patients who underwent cardiac surgery between 2016 and 2018. Weill Cornell Medicine, a single large academic medical center. The study comprised 78 patients undergoing elective cardiac surgery. CPB, TEE, pulmonary artery catheter, and elective cardiac surgery. Two-dimensional CO, 3D CO-diameter, and 3D CO-area values pre-CPB were strongly correlated with one another both pre-CPB and post-CPB. The 3D CO-diameter and the 3D CO-area were mildly correlated, with TDCO measurements pre-CPB (r = 0.46 and 0.39, respectively) and post-CBP (r = 0.43 and 0.47, respectively). Pre-CPB 3D CO-diameter had the most agreement with TDCO in terms of bias (-0.13 L/min); however, the limits of agreement (LOA) were wide (-2.2- to- 2.45 L/min). Post-CPB, 3D CO-diameter had the most agreement with TDCO in terms of bias (0.41) but with wide LOA (-3.29 to 2.47). All pre-CPB echocardiography-derived CO (2D CO, 3D CO-diameter, 3D CO-area) had more agreement with TDCO than did post-CPB measurements. Three-dimensional CO measurements were only modestly correlated with pulmonary artery catheter-derived CO pre-bypass and post-bypass. Despite low bias, the wide LOA from 2D CO, 3D CO-diameter, and 3D-area compared with TDCO suggested that the 2 methods are not interchangeable.

Multimodality imaging derived energy loss index and outcome after transcatheter aortic valve replacement.

To assess whether the combination of transthoracic echocardiography (TTE) and multidetector computed tomography (MDCT) data affects the grading of aortic stenosis (AS) severity under consideration of the energy loss index (ELI) in patients undergoing transcatheter aortic valve replacement (TAVR). Multimodality imaging was performed in 197 patients with symptomatic severe AS undergoing TAVR at the University Hospital Zurich, Switzerland. Fusion aortic valve area index (fusion AVAi) assessed by integrating MDCT derived planimetric left ventricular outflow tract area into the continuity equation was significantly larger as compared to conventional AVAi (0.41 ± 0.1 vs. 0.51 ± 0.1 cm2/m2; P < 0.01). A total of 62 patients (31.4%) were reclassified from severe to moderate AS with fusion AVAi being >0.6 cm2/m2. ELI was obtained for conventional AVAi and fusion AVAi based on sinotubular junction area determined by TTE (ELILTL 0.47 ± 0.1 cm2/m2; fusion ELILTL 0.60 ± 0.1 cm2/m2) and MDCT (ELIMDCT 0.48 ± 0.1 cm2/m2; fusion ELIMDCT 0.61 ± 0.05 cm2/m2). When ELI was calculated with fusion AVAi the effective orifice area was >0.6 cm2/m2 in 85 patients (43.1%). Survival rate 3 years after TAVR was higher in patients reclassified to moderate AS according to multimodality imaging derived ELI (78.8% vs. 67%; P = 0.01). Multimodality imaging derived ELI reclassifies AS severity in 43% undergoing TAVR and predicts mid-term outcome.

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

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). 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 (Aa ); (b) 5mm (A5 ); and (c) 10mm 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. Anatomical LVOT area increased from Aa to A10 (5.0±0.9cm2 vs 5.8±1.9cm2 , 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±1.9cm2 vs 3.4±1.1cm2 , P<.001). Although mean calculated SV by TTE was not significant at different LVOT levels (Aa 69±22mL, vs A5 66±21mL, vs A10 66±28±22mL, P>.05), the most significant variations in individuals were at A10 levels (ΔSV: 8.2±6.4mL, 12±9%). 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.

Three-dimensional versus two-dimensional transthoracic echocardiography for left ventricular outflow tract measurements in severe aortic stenosis. A cross-sectional study using computer tomography and Haegar sizers as reference

Objectives. In grading of aortic stenosis, two-dimensional transthoracic echocardiography (2D TTE) routinely results in underestimation of the left ventricular outflow tract (LVOT) area, and hence the aortic valve area (AVA). We investigated whether three-dimensional (3D) TTE measurements of the LVOT would be more accurate. We evaluated the feasibility, agreement and inter-observer variability of 3D TTE LVOT measurements with computed tomography (CT) and Haegar sizers as reference. Design. Sixty-one patients with severe aortic stenosis were examined with 2D and 3D TTE. 41 had CT and 13 also had perioperative Haegar sizing. Pearson’s correlation and Bland-Altman plots were used to compare methods. Inter-observer variability was tested for 2D and 3D TTE. Trial registration: Current research information system in Norway (CRISTIN). Id: 555249. Results. Feasibility was 67% with 3D TTE and 100% with 2D TTE and CT. Mean LVOT area for 2D, 3D, CT and Haegar sizers were 3.7 ± 0.6 cm2, 4.0 ± 0.9 cm2, 5.2 ± 0.8 cm2 and 4.4 ± 1.0 cm2 respectively. Bias and limits of agreements for 2D TTE was 1.5 ± 1.3 cm2, compared with CT and 0.4 ± 1.5 cm2 with Haegar sizers. Corresponding results for 3D TTE were 1.2 ± 1.6 cm2 and 0.2 ± 1.8 cm2. Intraclass correlation coefficients for LVOT area were 0.62 for 3D and 0.86 for 2D. Conclusions. 2D TTE showed better feasibility and inter-observer variability in measurements of LVOT than 3D TTE. Both echocardiographic methods underestimated LVOT area compared to CT and Haegar sizers. These observations suggest that 2D TTE is still preferable to 3D TTE in the assessment of aortic stenosis.

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

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. We prospectively studied 134 patients (median age, 80years; interquartile range, 73-87years; 39% women) with AS, including 82 (61%) with severe AS and 52 (39%) with mild or moderate AS. LVOTA was traced using direct planimetry (LVOTAbiplane) and compared with LVOTA calculated using the circular assumption (LVOTAcirc). In a subset of patients who underwent cardiac computed tomography, direct planimetry of LVOTA was used as a reference standard. LVOTAbiplane was significantly larger than LVOTAcirc (4.20cm2 [interquartile range, 3.66-4.90cm2] vs 3.73cm2 [interquartile range, 3.14-4.15cm2], P<.001). Among 30 patients who underwent cardiac computed tomography, LVOTAbiplane had better agreement with LVOTA by direct planimetry than LVOTAcirc (mean bias, -0.45±0.63 vs -1.02±0.63cm2; P<.0001). Of 82 patients with severe AS (AVA≤1cm2 using LVOTAcirc), 40 (49%) had discordant mean gradient (<40mm Hg). By using LVOTAbiplane, 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. 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.

TAVR outcome after reclassification of aortic valve stenosis by using a hybrid continuity equation that combines computed tomography and echocardiography data.

In the continuity equation, assumption of a round-shaped left ventricular outflow tract (LVOT) leads to underestimation of the true aortic valve area in two-dimensional echocardiography. The current study evaluated whether inclusion of the LVOT area, as measured by computed tomography (CT), reclassifies the degree of aortic stenosis (AS) and assessed the impact on patient outcome after transcatheter aortic valve replacement (TAVR). Four hundred and twenty-two patients with indexed aortic valve area index (AVAi) of <0.6 cm2 /m2 , assessed by using the classical continuity equation (mean age: 81.5 ± 6.1 years, 51% female, mean left ventricular ejection fraction: 53.2 ± 13.6%), underwent TAVR and were included. After inclusion of the CT measured LVOT area into the continuity equation, the hybrid AVAi led to a reclassification of 30% (n = 128) of patients from severe to moderate AS. Multivariate predictors for reclassification were male sex, lower mean aortic gradient, and lower annulus/LVOT ratio (all p < .01). Reclassified patients had significantly higher sST2 at baseline and higher NT-proBNP values at baseline and 6 months follow-up compared to non-reclassified patients. Acute kidney injury was experienced more frequently after TAVR by reclassified patients, but no significant mortality difference occurred during 2 years of follow-up. The hybrid AVAi reclassifies a significant portion of low-gradient severe AS patients into moderate AS. Reclassified patients showed increased fibrosis and heart failure markers at baseline compared to non-reclassified patients. But reclassification had no significant impact on mortality up to 2 years after TAVR. Routine assessment of hybrid AVAi seems not to improve further risk stratification of TAVR patients.

Three-Dimensional Modeling of Surgically Implanted Stent-Based Valves in the Mitral Position in Children

In children with a mitral annulus too small to accommodate traditional prostheses, surgical implantation of stent-based valves is a promising option. However no reliable preoperative methods exist to guide patient selection, device sizing, and positioning. We describe a novel methodology to visualize and quantify device fit in 3-dimensional echocardiogram (3DE)-derived heart models. Heart models were created from existing preoperative 3DEs using custom software. Valve models were virtually implanted into the models, and both device fit and left ventricular outflow tract (LVOT) area were quantified. The 3DEs of 3 patients who underwent Melody valve placement in the mitral position were retrospectively modeled: 1 with LVOT obstruction, 1 with perivalvar leak, and 1 without complications. In all cases 2-dimensional measurements underestimated 3D annular dimensions, and the patient with clinical LVOT obstruction had the lowest predicted LVOT area-to-aortic area ratio (0.5). 3DE-based preoperative modeling of surgical implantation of stent-based valves in the mitral position may improve quantification of mitral valve dimensions and inform risk stratification for potential LVOT obstruction.

CT VERSUS ECHOCARDIOGRAPHIC STROKE VOLUME INDEX COMPARED TO INVASIVELY DERIVED CARDIAC INDEX TO ASSESS FLOW IN PATIENTS WITH AORTIC STENOSIS

Echocardiographic (ECHO)-derived stroke volume index (SVI) is used to define flow state in patients with aortic stenosis (AS) as the product of left ventricular outflow tract (LVOT) area and time velocity integral. CT provides a better assessment of the LVOT area. We sought to determine low flow (LF

Aortic valve area using computed tomography-derived correction factor to improve the validity of left ventricular outflow tract measurements.

Given the inherent inaccuracies stemming from the assumption that the left ventricular outflow tract (LVOT) is circular, this study aimed to improve the accuracy of transthoracic echocardiography (TTE)-based aortic valve area (AVA) calculation using continuity equation (CE) by introducing a correction factor (CF) derived from multidetector computed tomography angiography (MDCTA) images and validate it in aortic stenosis (AS) patients. This retrospective study used MDCTA images of 400 patients for modeling and 403 TTE dataset for validation. Echocardiographic parasternal long-axis view was modeled using MDCTA, and LVOT diameter (D1) was measured. Direct planimetry of LVOT area was performed and subsequently converted into a theoretical circle. The assumed circle (D2) diameter was derived, and D2/D1 was calculated and termed as the CF. The CF was 1.13, and it improved the agreement between MDCTA- and TTE-derived LVOT areas and correlation between AVA and peak velocity, mean pressure gradient, and velocity ratio. In discordant subgroups of severe AS, the CF reclassified patients to moderate AS in 40% in the low flow (LF), low gradient (LG), and low ejection fraction (EF) group; 53% in the LF, LG, and normal EF group; and 68% in the LF, high gradient, and normal EF group. CF of 1.13 derived from MDCTA improved the accuracy of TTE-derived LVOT area and AVA and improved correlation with hemodynamic variables in AS patients. Reclassification of AS patients using CF may have clinical applicability for patient selection for early intervention.

P212 Computed tomography derived left ventricular outflow tract area downgrades severity of prosthesis-patient mismatch after transcatheter aortic valve replacement

Abstract Background Prosthesis-patient mismatch (PPM) is associated with poor outcomes after surgical aortic valve replacement, but evidence in the era of transcatheter aortic valve replacement (TAVR) is small. Although PPM is conventionally defined by transthoracic echocardiogram (TTE) derived indexed effective orifice area (EOAi), TTE may underestimate left ventricular outflow tract (LVOT) area when compared with cardiac computed tomography angiography (CTA). Purpose To evaluate the inter-modality (TTE vs CTA) agreement and inter-valve (balloon-expanding valve (BEV) vs. self-expandable valve (SEV)) differences in EOAi and the severity of PPM after TAVR. Methods We analyzed all patients who underwent TAVR between 2015 to 2017and who had both of CTA and TTE at 30-days after TAVR. EOAi was calculated using the continuity equation and then indexed to body surface area as per guidelines using TTE derived LVOT diameter (EOAi-TTE) or post-procedure CTA derived LVOT area (EOAi-CTA). The external LVOT diameter was measured at inflow of TAVR bioprosthetic stent frame as per recommendations. The EOAi was used to define the grading severity of PPM: None (&amp;gt; 0.85 cm²/m²); Moderate (0.65 to 0.85 cm²/m²); and Severe (&amp;lt; 0.65 cm²/m²). Paired or Student t-test and Chi-square test were used to assess the inter-modality and inter-valve difference. Results A total of 280 patients were included (the mean age, 81.2 ± 8.1 years; 48%, female). BEV was used in 150 patients (54%). The mean EOAi-TTE vs. EOAi-CTA was 1.00 ± 0.32 and 1.41 ± 0.50 cm²/m², respectively, p &amp;lt; 0.001. Prevalence of severe (TTE 9% versus CTA 4%, p &amp;lt; 0.01) and moderate (TTE 28% versus CTA 7%, p &amp;lt; 0.01) PPM was lower when adjudicated by CTA (Figure-Panel A). There was a trends towards smaller EOAi by either TTE (0.97 ± 0.31 vs. 1.04 ± 0.33, p = 0.07) or CTA (1.38 ± 0.45 vs. 1.46 ± 0.56, p = 0.21) for BEV vs. SEV (Figure-Panel B). There was no significant difference in the severity of PPM defined by either EOAi-TTE (Figure-Panel C) or EOAi-CTA (Figure-Panel D) between these patients. Conclusion EOAi-CTA was larger and downgraded the severity of PPM than the EOAi-TTE. There was no significant difference in the severity of PPM defined by post-procedure CT between patients treated with BEV and those with SEV. Abstract P212 Figure.

P768 Potential utility of fully automated Doppler flow velocity tracing software in patients with atrial fibrillation

Abstract Background Stroke volume (SV) using Doppler echocardiography is a significant prognosticator in patients with atrial fibrillation (AF). However, tracing multiple left ventricular outflow tract (LVOT) Doppler flow velocity envelope is tedious. Although ASE recommends to average 5 -10 beats of SV in AF, this has not been validated. Recently developed fully automated Doppler flow velocity analytical software can analyze Doppler parameters in multiple consecutive beats on the screen within a few seconds. Purpose We aimed to determine the usefulness of the software, and to validate the minimum number of beats required to approximate SV in patients with AF. Methods We selected 21 AF patients who had undergone 2D echocardiography using GE ultrasound machine (E95, GE healthcare). LVOT area was calculated by 3.14×(LVOT diameter/2)². LVOT pulse-wave Doppler velocity was recorded from an apical approach with a quiet breathing. To maximize the number of flow envelope on the screen, sweep speed was set at 12.5 mm/s. LVOT velocity time integral was measured by both manual tracing method and fully automated method (Cardiac Auto Doppler, GE healthcare). The grand truth of mean SV (reference SV) in each patient was defined as the averaged values of SV from all consecutive beats. We also calculated the mean SV value with the successive addition of sequential beats started from the 1st beat. Each value was compared with the reference SV and % variability was calculated. We determined the minimum number of beats showing %variability becoming &amp;lt;5%. Results Mean age was 77 years. Mean heart rate and reference SV index (SVI) were 80 ± 12 bpm and 35 ± 10 mL/m2. A total number of beats for recording was ranged from 16 to 25 in each patient. The fully automated software could analyze Doppler envelope in 395 out of 412 beats (Feasibility: 96%). Although there was a good correlation of SV in individual beats between the manual and automatic method (r = 0.92), the automatic method significantly overestimated SV (mean bias: 2.6 mL, p &amp;lt; 0.001) compared with the manual method. The median values of minimum number of beats showing % variability &amp;lt; 5% were 4 (interquartile range: 2 -7) for manual tracing method. The corresponding values were 5 (2 -6) for automatic method. If we used mean values of SV during consecutive 10 beats, 92% of patients using manual method and 96% of patients using automatic method showed % variability &amp;lt; 5%. There were excellent correlation between reference SV and averaged SV from the 1st beat to 10th beat (manual: r = 0.98, automatic: r = 0.99). If we defined low flow status as &amp;lt; 35 mL/m2, averaged SVI during consecutive 10 beats using the automatic method had a correct diagnosis in 20 out of 21 patients. Conclusions We concluded that minimum number of required beats for averaging was 10 in most AF patients. Rapid and reliable SV analysis with a novel fully automated Doppler software has a potential for its adoption in busy echocardiography laboratories.

P300 Reappraisal of aortic stenosis severity grading inconsistencies using 3D aortic valve area

Abstract Funding Acknowledgements no fundings Background Different 3D imaging modalities have been proposed to overcome the limitations in aortic stenosis (AS) grading derived from underestimation of left ventricular outflow tract (LVOT) area by 2D transthoracic echocardiography (2D-TTE). Transesophageal echocardiography manual and software measurements (3D-TEEm and 3D-TEEs) and multidetector computed tomography (MDCT) have been recently been shown as valuable tools for AS grading using a combined approach incorporating 3D LVOT measurements and 2D Doppler parameters in the continuity equation (CE). This approach results particularly useful in cases of 2D-TTE grading inconsistence. As all these 3D imaging modalities provide larger AVA compared to 2D-TTE, we have recently proposed a 1.2 cm2 AVA cut-off could to define AS severity with 3D-TEE and MDCT. Purpose To compare AVA measurements with 3D-TEEm and 3D-TEEs using MDCT as gold standard in order to assess inconsistencies and evaluate the impact of a 1.2 cm2 AVA cut-off on AS severity grading. Methods 288 patients (80 ± 11 years, 52.4% male) with symptomatic AS underwent 2D-TTE, 3D-TTEm, 3D-TEEs and MDCT within the same hospitalization. 3D-TEE LVOT reconstruction was performed manually and with semi-automated software (EchoPAC version 201). 3D-TEEm, 3D-TEEs and MDCT LVOT areas were combined with 2D-TTE Doppler parameters to calculate AVA by CE. The grading of AS was reassessed in patients with low flow-low gradient AS using a 1.2 cm2 cut-off for severity. Results Patients were classified according to flow state (stroke volume index ≥35 ml/m2 or &amp;lt;35 ml/m2) and mean pressure gradient (MPG ≥40 mmHg or &amp;lt;40 mmHg) into 4 groups: normal flow-high gradient (NF-HG; n 173, 60%), normal flow-low gradient (NF-LG; n 45, 15.5%), low flow-high gradient (LF-HG; n 39, 13.5%), and low flow-low gradient (LF-LG; n 31, 11%) AS. Among patients classified as LF-LG AS, 95%, 55%, 29% and 55% of cases were classified as severe by 2D-TTE, 3D-TEEm, 3D-TEEs and MDCT respectively using a 1.0 cm2 AVA cut-off. When the proposed severity AVA cut-off of 1.2 cm2 was applied using 3D imaging modalities, the proportion of severe AS significantly increased to 84% (p = 0.012) (3D-TEEm), 52% (p = 0.046) (3D-TEEs) and 71% (p &amp;lt; 0.001) (MDCT) respectively. Conclusion The use of a 1.2 cm2 AVA cut-off for 3D-TEE and MDCT significantly reduces the number of cases of inconsistently graded AS, increasing the proportion of patients with severe AS.

Impact of left ventricular outflow tract flow acceleration on aortic valve area calculation in patients with aortic stenosis

Objective: Due to its circular shape, the area of the proximal left ventricular tract (PLVOT) adjacent to aortic valve can be derived from a single linear diameter. This is also the location of flow acceleration (FA) during systole, and pulse wave Doppler (PWD) sample volume in the PLVOT can lead to overestimation of velocity (V1) and the aortic valve area (AVA). Therefore, it is recommended to derive V1 from a region of laminar flow in the elliptical shaped distal LVOT (away from the annulus). Besides being inconsistent with the assumptions of continuity equation (CE), spatial difference in the location of flow and area measurement can result in inaccurate AVA calculation. We evaluated the impact of FA in the PLVOT on the accuracy of AVA by continuity equation (CE) in patients with aortic stenosis (AS).Methods: CE-based AVA calculations were performed in patients with AS once with PWD-derived velocity time integral (VTI) in the distal LVOT (VTILVOT) and then in the PLVOT to obtain a FA velocity profile (FA-VTILVOT) for each patient. A paired sample t-test (P < 0.05) was conducted to compare the impact of FA-VTILVOT and VTILVOT on the calculation of AVA.Result: There were 46 patients in the study. There was a 30.3% increase in the peak FA-VTILVOT as compared to the peak VTILVOT and AVA obtained by FA-VTILVOT was 29.1% higher than obtained by VTILVOT. p]Conclusion: Accuracy of AVA can be significantly impacted by FA in the PLVOT. LVOT area should be measured with 3D imaging in the distal LVOT.

Predicting the outcome of transcatheter mitral valve implantation using image-based computational models

BackgroundThe appropriate placement and size selection of mitral prostheses in transcatheter mitral valve implantation (TMVI) is critical, as encroachment on the left ventricular outflow tract (LVOT) may lead to flow obstruction. Recent advances in computed tomography (CT) can be employed for pre-procedural planning of mitral prosthetic valve placement. This study aims to develop patient-specific computational fluid dynamics models of the left ventricle (LV) in the presence of a mitral valve prosthesis to investigate blood flow and LVOT pressure gradient during systole. MethodsPatient-specific computational fluid dynamics simulations of TMVI with varied cardiac anatomy and insertion angles were performed (n = 30). Wide-volume full cycle cardiovascular CT images prior to TMVI were used as source anatomical data (n = 6 patients). Blood movement was governed by Navier-Stokes equations and the LV endocardial wall deformation was derived from each patient's CT images. ResultsThe computed pressure gradients in the presence of the mitral prosthesis compared well with clinically measured gradients. Analysis of the effects of prosthetic valve angulation, aorto-mitral annular angle, ejection fraction, LV size and new LVOT area (neo-LVOT) after TMVI in silico revealed that the neo-LVOT area (p < 0.001) was the most significant factor affecting LVOT pressure gradient. Angulation of the mitral valve can substantially mitigate LVOT gradient. ConclusionsComputational fluid dynamics simulation is a promising method to aid in pre-TMVI planning and understanding the factors underlying LVOT obstruction.

P928Pseudo-discordance mimicking low-flow low-gradient AS in TAVR patients with severe symptomatic aortic stenosis

Abstract Background The combination of a small aortic valve area valve area (AVA) and a low mean gradient (MG) severity pose a serious clinical challenge in the diagnosis of severe aortic stenosis (AS). While this discordance is frequently labeled “low-flow low-gradient AS”, there are two additional potential causes: underestimation of MG and underestimation of AVA. Purpose To investigate prevalence and root causes of discordant echocardiographic findings in symptomatic patients with AS and normal LV function by comparing Doppler data, invasive hemodynamic data, CT LV outflow tract size and calcium score. Methods and results We studied 67 severely symptomatic patients with AS and an LVEF&gt;50%. Thirty patients (45%) had discordant echocardiographic findings (MG&lt;40 mmHg, AVA≤1cm2). Of those, 16 had also discordant findings by invasive measurements (True Discordants), compatible with low-gradient severe AS. In 14, catheterization data were actually concordant and hence discrepant to the echocardiographic findings (False Discordants): In 7 of them, the echocardiographic MG was &gt;35 mmHg; in 5 it was &gt;30 mmHg and only in 2 between 25 and 29 mmHg. In 6 of the 14 patients with underestimated MG, no right parasternal Doppler examination had been performed, LVOT VTI tracings were clearly suboptimal in 3 patients and 1 case was deemed inadequate due to poor imaging quality. LVOT area by echocardiography or by CT could not differentiate between Concordants and Discordants (p=0.3 and p=0.8 respectively) or between True and False Discordants (p=0.5 and p=0.6 respectively). While calcium score was similar in Concordants (2711±1159 AU) and False Discordants (2692±1136AU, p=0.96), it tended to be higher in Concordants (2711±1159 AU), when compared to True Discordants (1906±1284 AU, p=0.07). In patients with concordant echocardiographic findings calcium score levels of &gt;3000 AU in men and &gt;1600 AU in female had a positive predictive value (PPV) of 90% for the correct diagnosis of severe aortic stenosis. In patients with discordant findings the PPV was 80%. Conclusions 1) The majority of severely symptomatic AS patients with normal LV systolic function an echocardiographic AVA≤1.0 cm2 and a MG&gt;30mmHg considered for TAVR have severe AS by calcium score. 2) In this patient population, discordant echocardiographic findings are in about half of the cases due to technical factors (“pseudo-discordance”) rather than due to true low flow low-gradient stenosis. 3) Pseudo-discordance is mainly due to mild-moderate underestimation of gradients, caused by a lack of reliable right parasternal tracings, rather than due to underestimation of valve area due to the echocardiographic circularity assumption in the presence of an elliptical LVOT. 4) The diagnosis of true low-flow AS cannot be established without a clear Doppler tracing from the right parasternal window. 5) Absent an adequate right parasternal window, patients should undergo CT assessment of calcium score.

P4382O2-pulse measure obtained by gas exchange analysis is an accurate esteeme of stroke volume?

Abstract Background It is axiomatic that exercise performances depends on cardiac output increase. Among several methods for noninvasively estimating stroke volume, O2 pulse (i.e. the ratio of VO2/HR) is generally used during gas exchange analysis, but its accuracy has never been well investigated. Purpose To test the validity and the accuracy of O2 pulse as a measure of stroke volume (SV) in comparison with the echocardiographic methods. Methods From 22nd of August 2016 to 30th of April 2018 our laboratory performed 259 cardiopulmonary exercise tests (CPET) combined with echo. The group of patients was characterized by a heterogeneous spectrum of diseases: 70 coronary artery disease, 10 heart failure with preserved ejection fraction, 13 heart failure with middle ejection fraction, 26 heart failure with reduced ejection fraction, 29 Fabry disease, 7 hypertrophic cardiomyopathy, 10 dilated cardiomyopathy, 30 aortic stenosis, 16 aortic regurgitation, 8 mitral stenosis, 76 mitral regurgitation, 6 tricuspid regurgitation, 7 congenital heart diseases. The median age was 65 yr (52,5; 74,5) and 61,5% of patients was male. In our group are present 20 healthy subjects with normal heart. O2 pulse was measured at rest, at 2 minutes, 4 minutes, 6 minutes and at maximum of stress. In some cases the maximum of stress correspond to 4- or 6-minutes of stress. All the echocardiographic images were taken with Epiq7C, Philips. The left ventricle SV was measured as SV = LVOT area x LVOT VTI, all the measures and the images where acquired by the same operator to reduce at minimum the external error introduce by the operator. Results As first step we analysed the absolute value of O2-pulse and SV at rest and during the different steps of exercise to see if and how they behave. In the figure attached is possible to see that both the values increased during the exercise with a small reduction at the maximum that may be explained by a premature interruption of the exercise. Secondly we analysed the correlation between O2 pulse and LVOT-SV at rest and during 2-, 4-, 6- minutes of exercise and at maximum which was respectively: r=0,23 (p&lt;0,0001), r=0,36 (p&lt;0,0001), r=0,30 (p&lt;0,0001), r=0,25 (p&lt;0,0001) and r=0,51 (p&lt;0,0001) (see figure 2). The analysis has been possible in 259 patients at rest, in 246 at 2-minutes of stress, in 221 at 4-minutes of stress and in 149 patients at 6-minutes of stress. At maximum of exercise, the analysis has been carried out in 229 patients, but we need to keep in mind that maximum of stress includes both 4- and 6-minutes of exercises according to the capability of each patients. Conclusion In our analysis we show an incremental trend during exercise of O2-Pulse value and of LVOT-SV. At rest and during exercise it is present a good correlation between O2-pulse and LVOT-SV. These data reinforce the concept that O2 pulse reflects an estimation of SV and may explain its reported prognostic validity in prospective studies.

P2270Clinical characteristics and outcomes after TAVI in patients reclassified to moderate aortic stenosis by integration of multimodality imaging and pressure recovery

Abstract Background Accurate assessment of aortic stenosis (AS) severity is critical for the correct management of patients. This has become particularly important because the introduction of transcatheter aortic valve implantation (TAVI) has markedly increased the number of patients eligible for aortic valve replacement Aims To assess whether reclassification of aortic stenosis (AS) grading by integration of fusion imaging using data from transthoracic echocardiography (TTE) and multidetector computed tomography (MDCT) under consideration of the energy loss index (ELI) predicts outcome in patients undergoing transcatheter aortic valve implantation (TAVI). Methods 197 consecutive patients with symptomatic severe AS undergoing TAVI at our University Heart Center were included in this study. AS severity was determined according to current guidelines. Results Left ventricular outflow tract (LVOT) area derived from TTE was smaller than the planimetric area in MDCT due the ovoid shape of the LVOT (3.4±0.12 cm2 vs. 4.5±0.23 cm2; p&lt;0.01). The sinotubular junction (ST-junction) diameter measured in TTE was similar to maximal, minimal, and mean diameters determined by MDCT. The sphericity index confirmed an almost circular anatomy of ST-junction, and its area derived from TTE was similar to the planimetric area in MDCT. Fusion aortic valve area index (fusion AVAi) assessed by inserting MDCT derived planimetric LVOT area in the continuity equation was significantly higher in all patients compared to conventional AVAi. 62 patients were reclassified from severe to moderate AS because fusion AVAi was &gt;0.6 cm2/m2. ELI was calculated for conventional AVAi and fusion AVAi each with ST-junction area determined by both TTE and MDCT. Calculating ELI with fusion AVAi resulted in significantly larger effective orifice area, with values &gt;0.6 cm2/m2 in 83 patients (ST-junction area from echo) and 85 patients (ST-junction area from MDCT). Similarly, calculating ELI with conventional AVAi resulted in significantly larger effective orifice area as compared to AVAi alone. Reclassified patients had lower mean transvalvular pressure gradients, lower myocardial mass, less symptoms according to NYHA classification, and lower proBNP levels at baseline. While both groups exhibited improvement of functional status at 1 year of follow-up, the survival rate at 3 years after TAVI was higher in patients reclassified to moderate AS (81% versus 66%; p=0.02). Conclusion Integration of TTE and MDCT derived values for calculation of ELI reclassifies the severity of AS in 43% of patients initially diagnosed with severe AS.Although reclassified patients display less advanced valve disease at baseline, TAVI results in functional improvement in all patients. Furthermore, patients reclassified to moderate AS exhibit higher survival rates at 3 years after aortic valve replacement.

Three-Dimensional Echocardiography for Transcatheter Aortic Valve Replacement Sizing: A Systematic Review and Meta-Analysis.

BackgroundTranscatheter aortic valve replacement (TAVR) is the standard of care for many patients with severe symptomatic aortic stenosis and relies on accurate sizing of the aortic annulus. It has been suggested that 3‐dimensional transesophageal echocardiography (3D TEE) may be used instead of multidetector computed tomography (MDCT) for TAVR planning. This systematic review and meta‐analysis compared 3D TEE and MDCT for pre‐TAVR measurements.Methods and ResultsA systematic literature search was performed. The primary outcome was the correlation coefficient between 3D TEE– and MDCT‐measured annular area. Secondary outcomes were correlation coefficients for mean annular diameter, annular perimeter, and left ventricular outflow tract area; interobserver and intraobserver agreements; mean differences between 3D TEE and MDCT measurements; and pooled sensitivities, specificities, and receiver operating characteristic area under curve values of 3D TEE and MDCT for discriminating post‐TAVR paravalvular aortic regurgitation. A random effects model was used. Meta‐regression and leave‐one‐out analysis for the primary outcome were performed. Nineteen studies with a total of 1599 patients were included. Correlations between 3D TEE and MDCT annular area, annular perimeter, annular diameter, and left ventricular outflow tract area measurements were strong (0.86 [95% CI, 0.80–0.90]; 0.89 [CI, 0.82–0.93]; 0.80 [CI, 0.70–0.87]; and 0.78 [CI, 0.61–0.88], respectively). Mean differences between 3D TEE and MDCT between measurements were small and nonsignificant. Interobserver and intraobserver agreement and discriminatory abilities for paravalvular aortic regurgitation were good for both 3D TEE and MDCT.ConclusionsFor pre‐TAVR planning, 3D TEE is comparable to MDCT. In patients with renal dysfunction, 3D TEE may be potentially advantageous for TAVR measurements because of the lack of contrast exposure.

Comparison of Cardiac Output of Both 2-Dimensional and 3-Dimensional Transesophageal Echocardiography With Transpulmonary Thermodilution During Cardiac Surgery

To compare agreement and variability of cardiac output measurement of 2-dimensional (2D) and 3D transesophageal echocardiography (TEE) with thermodilution before and after bypass. Prospective observational study. Two tertiary hospitals. Cardiac output (CO) was measured simultaneously with thermodilution and TEE by multiplying either the left ventricular outflow tract area (LVOTA) or aortic valve area (AVA), the velocity-time integral (VTI) of flow at the same site, and heart rate. The LVOTA was calculated using diameter for 2D TEE. Planimetry was used for 3D TEE. The AVA was measured using planimetry. The study comprised 82 adult patients undergoing coronary or valve surgery. One hundred fifty-four complete sets of measurements were obtained (82 prebypass and 72 postbypass). All TEE methods had acceptable correlation and absence of proportional or fixed bias except for the left ventricular outflow tract (LVOT) VTI modal trace method, which had poor correlation and proportional but not fixed bias (regression coefficient [95% confidence interval], bias [percentage of mean CO]): 2D LVOT VTI modal trace 0.67 (0.54-0.80), -36.4%; 2D LVOT VTI outer edge trace 0.96 (0.80-1.12), -15.3%; 2D AVA planimetry 0.96 (0.75-1.18), +4.9%; 3D LVOT area planimetry 1.18 (0.96-1.41), +0.8%; 3D AVA planimetry 1.20 (0.93-1.46), +0.4%. All TEE methods had wide levels of agreement compared with thermodilution (-3.94 to +0.23 L/min, -2.83 to +1.28 L/min, -2.23 to +2.73 L/min, -2.35 to +2.42 L/min, and -2.57 to +2.61 L/min, respectively). Measurement variability was superior for all TEE methods compared with thermodilution before but not after bypass. Although limits of agreement of CO measurement with 3D TEE and thermodilution are wide, 2D planimetry of the AVA and continuous wave Doppler may be substituted for thermodilution before and after bypass.

Unique electrocardiographic pattern \u201cw\u201d wave in lead I of idiopathic ventricular arrhythmias arising from the distal great cardiac vein

BackgroundThe ECG characteristics of the distal coronary venous system ventricular arrhythmias (VAs) share common features with VAs arising from the aortic cusps or the endocardial left ventricular outflow tract (LVOT) beneath the cusps. The purpose of this study was to identify specific electrocardiographic and electrophysiological characteristics of VAs originating from the distal great cardiac vein (GCV).MethodsBased on the successful ablation site, patients with idiopathic VAs from the distal GCV, left coronary cusp (LCC) or the subvalvular left ventricular outflow tract (LVOT) area were included in the present study.ResultsThe final population consisted of 39 patients (35 males, mean age 51 ± 23 years). All VAs displayed a right bundle branch block (RBBB) morphology with inferior axis. Among these patients, 15 were successfully ablated at the GCV, 15 at the LCC and 9 at the subvalvular region. A “w” pattern in lead I was present in 12 out of 15 (80%) VAs originating from the distal GCV compared to none of VAs arising from the other two sites (p < 0.01). VAs with a GCV origin exhibited more commonly increased intrinsicoid deflection time, higher maximum deflection index and wider QRS duration compared to LCC and subvalvular sites (p < 0.05). Acceptable pace mapping at the successful ablation site was achieved in 10 patients. After an average of 36 ± 24 months follow up, 14 (93.3%) patients were free from VAs recurrence.ConclusionA “w” pattern in lead I may distinguish distal GCV VAs from VAs arising from the LCC or the subvalvular region.