Left ventricle geometry, atrial strain, ventricle strain and hemodynamics across aortic valve before and after transcatheter aortic valve replacements

Background: Transcatheter Aortic Valve Replacements (TAVR) has become widespread throughout the world. To date there are no echocardiographic study of TAVR patients from Southeast Asia (SEA). We sought to evaluate 1) changes in echocardiographic and strain values pre and post TAVR 2) relationship between aortic stenosis (AS) severity and strain values, 3) left ventricle geometry in severe AS 4) relationship of flow rate to dimensionless index (DVI) and acceleration time (AT) and 5) effect of strains on outcome. Methods: Retrospective study of 112 TAVR patients in our center from 2009 to 2020. The echocardiographic and strain images pre (within 1 months), post (day after) and 6 months post TAVR were analyzed by expert echocardiographer. Results: The ejection fraction (EF) increased at 6 months (53.02 ± 12.12% to 56.35 ± 9.00%) (p=0.044). Interventricular septal thickness in diastole (IVSd) decreased (1.27 ± 0.21cm to 1.21 ± 0.23cm) (p=0.038) and left ventricle internal dimension in diastole (LVIDd) decreased from 4.77 ± 0.64cm to 4.49 ± 0.65cm (p = 0.001). No changes in stroke volume index (SVI pre vs 6 months p =0.187), but the flow rate increases (217.80 ± 57.61mls/s to 251.94 ± 69.59mls/s, p<0.001). Global Longitudinal Strain (GLS) improved from -11.44 ± 4.23% to -13.94 ± 3.72% (p <0.001), Left Atrial Reservoir strain (Lar-S) increased from 17.44 ± 9.16% to 19.60 ± 8.77% (p=0.033). 8 patients (7.5%) had IVSd < 1.0cm, and 4 patients (3.7%) had normal left ventricle (LV) geometry. There was linear relationship between IVSd and mean PG (r=0.208, p=0.031), between GLS to aortic valve area (AVA) and aortic valve area index (AVAi) (r = – 0.305, p=0.001 and r= – 0.316, p = 0.001). There was also relationship between AT (r=-0.20, p=0.04) and DVI (r=0.35, p< 0.001) with flow rate. Patients who died late (after 6 months) had lower GLS at 6 months. (Alive; -13.94 ± 3.72% vs Died; -12.43 ± 4.19%, p= 0.001) Conclusion: At 6 months TAVR cause reverse remodeling of the LV with reduction in IVSd, LVIDd and improvement in GLS and LAr-S. There is linear relationship between GLS and AVA and between IVSd and AVA.

Imaging Challenges in Patients with Severe Aortic Stenosis and Heart Failure: Did We Find a Way Out of the Labyrinth?

Aortic stenosis (AS) is the most frequent degenerative valvular disease in developed countries. Its incidence has been constantly rising due to population aging. The diagnosis of AS was considered straightforward for a very long time. High gradients and reduced aortic valve area were considered as “sine qua non” in diagnosis of AS until a growing body of evidence showed that patients with low gradients could also have severe AS with the same or even worse outcome. This completely changed the paradigm of AS diagnosis and involved large numbers of parameters that had never been used in the evaluation of AS severity. Low gradient AS patients may present with heart failure (HF) with preserved or reduced left ventricular ejection fraction (LVEF), associated with changes in cardiac output and flow across the aortic valve. These patients with low-flow low-gradient or paradoxical low-flow low-gradient AS are particularly challenging to diagnose, and cardiac output and flow across the aortic valve have become the most relevant parameters in evaluation of AS, besides gradients and aortic valve area. The introduction of other imaging modalities in the diagnosis of AS significantly improved our knowledge about cardiac mechanics, tissue characterization of myocardium, calcium and inflammation burden of the aortic valve, and their impact on severity, progression and prognosis of AS, not only in symptomatic but also in asymptomatic patients. However, a variety of novel parameters also brought uncertainty regarding the clinical relevance of these indices, as well as the necessity for their validation in everyday practice. The aim of this review is to summarize the prevalence of HF in patients with severe AS and elaborate on the diagnostic challenges and advantages of comprehensive multimodality cardiac imaging to identify the patients that may benefit from surgical or transcatheter aortic valve replacement, as well as parameters that may help during follow-up.

A novel approach to determine aortic valve area with phase-contrast cardiovascular magnetic resonance

Background Transthoracic echocardiography (TTE) is the diagnostic routine standard for assessing aortic stenosis (AS). However, its inaccuracies in determining stroke volume (SV) and aortic valve area (AVA) call for a more precise and dependable method. Phase-contrast cardiovascular magnetic resonance imaging (PC-CMR) is a promising tool to push these boundaries. Thus, the aim of this study was to validate a novel approach based on PC-CMR against the gold-standard of invasive determination of AVA in AS compared to TTE. Methods A total of 50 patients with moderate or severe AS underwent TTE, cardiac catheterization and CMR. AVA via PC-CMR was determined by plotting momentary flow across the valve against flow-velocity. SV by CMR was measured directly via PC-CMR and volumetrically using cine-images. Invasive SV and AVA were determined via Fick-principle and Gorlin-formula, respectively. TTE yielded SV and AVA using continuity equation. Gradients were calculated via the modified Bernoulli-equation. Results SV by PC-CMR (85 ± 31 ml) correlated strongly (r: 0.73, p < 0.001) with cine-CMR (85 ± 19 ml) without significant bias (lower and upper limits of agreement (LLoA and ULoA): − 41 ml and 44 ml, p = 0.83). In PC-CMR, mean pressure gradient correlated significantly with invasive determination (r: 0.36, p = 0.011). Mean AVA, as determined by PC-CMR during systole (0.78 ± 0.25 cm2), correlated moderately (r: 0.54, p < 0.001) with invasive AVA (0.70 ± 0.23 cm2), resulting in a small bias of 0.08 cm2 (LLoA and ULoA: − 0.36 cm2 and 0.55 cm2, p = 0.017). Inter-methodically, AVA by TTE (0.81 ± 0.23 cm2) compared to invasive determination showed similar correlations (r: 0.58, p < 0.001 with a bias of 0.11 cm2, LLoA and ULoA: − 0.30 and 0.52, p < 0.001) to PC-CMR. Intra- and interobserver reproducibility were excellent for AVA (intraclass-correlation-coefficients of 0.939 and 0.827, respectively). Conclusions Our novel approach using continuous determination of flow-volumes and velocities with PC-CMR enables simple AVA measurement with no bias to invasive assessment. This approach highlights non-invasive AS grading through CMR, especially when TTE findings are inconclusive.

Preoperative Computed Tomography Angiography Reveals Leaflet-Specific Calcification and Excursion Patterns in Aortic Stenosis

Background: Computed tomography–based evaluation of aortic stenosis (AS) by calcium scoring does not consider interleaflet differences in leaflet characteristics. Here, we sought to examine the functional implications of these differences. Methods: We retrospectively reviewed the computed tomography angiograms of 200 male patients with degenerative calcific AS undergoing transcatheter aortic valve replacement and 20 male patients with normal aortic valves. We compared the computed tomography angiography (CTA)-derived aortic valve leaflet calcification load (AVLC CTA ), appearance, and systolic leaflet excursion (LE sys ) of individual leaflets. We performed computer simulations of normal valves to investigate how interleaflet differences in LE sys affect aortic valve area. We used linear regression to identify predictors of leaflet-specific calcification in patients with AS. Results: In patients with AS, the noncoronary cusp (NCC) carried the greatest AVLC CTA (365.9 [237.3–595.4] Agatston unit), compared to the left coronary cusp (LCC, 278.5 [169.2–478.8] Agatston unit) and the right coronary cusp (RCC, 240.6 [137.3–439.0] Agatston unit; both P <0.001). However, LCC conferred the least LE sys (42.8º [38.8º–49.0º]) compared to NCC (44.8º [41.1º–49.78º], P =0.001) and RCC (47.7º [42.0º–52.3º], P <0.001) and was more often characterized as predominantly thickened (23.5%) compared to NCC (12.5%) and RCC (16.5%). Computer simulations of normal valves revealed greater reductions in aortic valve area following closures of NCC (−32.2 [−38.4 to −25.8]%) and RCC (−35.7 [−40.2 to −32.9]%) than LCC (−24.5 [−28.5 to −18.3]%; both P <0.001). By linear regression, the AVLC CTA of NCC and RCC, but not LCC, predicted LE sys (both P <0.001) in patients with AS. Both ostial occlusion and ostial height of the right coronary artery predicted AVLC CTA, RCC ( P =0.005 and P =0.001). Conclusions: In male patients, the AVLC CTA of NCC and RCC contribute more to AS than that of LCC. LCC’s propensity for noncalcific leaflet thickening and worse LE sys , however, should not be underestimated when using calcium scores to assess AS severity.

Physical and Physiologic Effects of Dobutamine Stress Echocardiography in Low-Gradient Aortic Stenosis

Background: Dobutamine stress echocardiography (DSE) is a useful tool for assessing low-gradient significant aortic stenosis (AS) and contractile reserve (CR), but its prognostic utility has become controversial in recent studies. We evaluated the impact of DSE on aortic valve physiological, structural and left ventricular parameters in low gradient AS. Methods: Consecutive patients undergoing DSE for low-gradient AS evaluation from September 2010 to July 2016 were retrospectively studied, and DSE findings divided into four groups with and without severe AS and CR. Relationships between left ventricular chamber quantification, CR, aortic valve Doppler during DSE and calcium score (by CT) were analysed. Results: There were 258 DSE studies performed on 243 patients, mean age 77.6±10.8 years and 183 (70.1%) were male. With increasing dobutamine dose, apart from systolic blood pressure, left ventricular ejection fraction, flow, cardiac power output and longitudinal strain magnitude, along with aortic valve area and mean aortic gradient all significantly increased (P<0.05). Flow and mean gradient increased in both the presence and absence of CR, whereas stroke volume and aortic valve area increased mainly in those with CR only. The aortic valve area increased in both patients with low and high calcium score, however the baseline area was lower in those with a higher calcium score. Conclusion: During DSE, aortic valve area increases with increase aortic valve gradient. Higher calcium score is associated with lower baseline aortic valve area, but the area valve area still increases with dobutamine even in presence of high calcium score.

Valvulo-Arterial Impedance and Dimensionless Index for Risk Stratifying Patients With Severe Aortic Stenosis

The hemodynamic effects of aortic stenosis (AS) consist of increased left ventricular (LV) afterload, reduced myocardial compliance, and increased myocardial workload. The LV in AS patients faces a double load: valvular and arterial loads. As such, the presence of symptoms and occurrence of adverse events in AS should better correlate with calculating the global burden faced by the LV in addition to the transvalvular gradient and aortic valve area (AVA). The valvulo-arterial impedance (Zva) is a useful parameter providing an estimate of the global LV hemodynamic load that results from the summation of the valvular and vascular loads. In addition to calculating the global LV afterload, it is paramount to estimate the stenosis severity accurately. In clinical practice, the management of low-flow low-gradient (LF-LG) severe AS with preserved LV ejection fraction requires careful confirmation of stenosis severity. In addition to the Zva, the dimensionless index (DI) is a very useful parameter to express the size of the effective valvular area as a proportion of the cross-section area of the left ventricular outlet tract velocity-time integral (LVOT-VTI) to that of the aortic valve jet (dimensionless velocity ratio). The DI is calculated by a ratio of the sub-valvular velocity obtained by pulsed-wave Doppler (LVOT-VTI) divided by the maximum velocity obtained by continuous-wave Doppler across the aortic valve (AV-VTI). In contrast to AVA measurement, the DI does not require the calculation of LVOT cross-sectional area, a major cause of erroneous assessment and underestimation of AVA. Hence, among patients with LG severe AS and preserved LV ejection fraction, calculation of DI in routine echocardiographic practice may be useful to identify a subgroup of patients at higher risk of mortality who may derive benefit from aortic valve replacement. This article aims to elucidate the Zva and DI in different clinical situations, correlate with the standard indexes of AS severity, LV geometry, and function, and thus prove to improve risk stratification and clinical decision making in patients with severe AS.

229 Long-term clinical and echocardiographic outcome following TAVR in patients with severe aortic stenosis and different transvalvular flow state

Aims Haemodynamic classifications of severe aortic stenosis (AS) have important prognostic implications, with low flow state (defined on the basis of a stroke volume index, SVi&lt;35 mL/m2) known to be a predictor of worse prognosis. As transcatheter aortic valve replacement (TAVR) has become widely used for patients with severe AS, issues were raised concerning its efficacy in patients with different haemodynamic classifications combining transvalvular flow state and pressure gradients. In fact, data on TAVR outcomes in patients with low gradient (LG) AS are limited and in some cases controversial. The aim of this study was to evaluate the efficacy and long-term clinical and echocardiographic outcome of TAVR in patients with different transvalvular flow-gradient patterns. Methods In this single centre study, 1078 patients (mean age 81±7 years) with severe symptomatic AS (AVA&lt;1 cm2) undergoing TAVR were categorized according to flow-gradient patterns as follow: 867 patients (80%) with normal flow-high gradient (NF-HG: mean transaortic gradient DP mean&gt;40 mmHg), 94 (9%) with paradoxical low flow LG (pLF-LG: DP mean&lt;40 mmHg, ejection fraction EF &gt; 50%, and SVi&lt;35 mL/m2), and 117 (11%) classical LF-LG (DP mean&lt;40 mmHg, EF &lt; 50%, SVi&lt;35 mL/m2). Results TAVR was feasible in all AS subtypes with similar rate of unsuccessful procedure (1.3% NF-HG, 1.1% pLF-LG, 0% LF-LG P=470). Valvular function after TAVR was excellent over time with respect to aortic pressure gradient (mean and peak) and aortic valve area regardless of flow state group (Figure A). Overall, intraoperative (P=957) and 30-day mortality (P=817) did not differ significantly among the 3 groups. Longer follow-up showed that, compared to NF-HG patients, pLF-LG had similar all-cause mortality rate [HR 1.35(0.95–1.90), P=0.094] up to 5 years and LF-LG had a significant higher mortality rate [HR 1.89(1.43–2.49), P&lt;0.001],(Figure B). Moreover, LF-LG patients had higher rehospitalization for heart failure (NF-HG: 3%, pLF-LG: 6%, LF-LG 10%, P=0.001). Conclusions We provided evidence that TAVR is an effective procedure in all patients with severe AS regardless of transvalvular flow-gradient patterns. A careful haemodynamic classifications of severe AS is of utmost importance for identifying patients who benefits the most from TAVR procedure.

90 Annular size and interaction with trans-catheter aortic valves for the treatment of severe bicuspid aortic valve stenosis: insights from the beat registry

Aims Transcatheter aortic valve replacement (TAVR) is safe and feasible in patients with bicuspid aortic valve (BAV), but whether annular size may influence TAVR results in BAV patients remains unclear. We aimed at evaluating the impact of aortic annular size on procedural and clinical outcomes of BAV patients undergoing TAVR, as well as potential interactions between annular dimension and trans-catheter heart valve (THV) type [balloon-expandable (BEV) vs. self-expanding (SEV)]. Methods and results BEAT is a multicentre registry of consecutive BAV stenosis undergoing TAVR. For this sub-study patients were classified according to annular dimension in small-annulus (area &lt; 400 mm2 or perimeter &lt;72 mm), medium-annulus (area ≥ 400 and &lt; 575 mm2, perimeter ≥72 mm and&lt; 85 mm), large-annulus (area ≥575 mm2 or perimeter ≥85 mm). Primary endpoint was Valve Academic Research Consortium-2 (VARC-2) device success. 45(15.5%) patients had small, 132(45.3%) medium, and 114(39.2%) large annuli. Compared with other groups, patients with large annuli were more frequently male, at younger age, had higher body mass index, larger aortic valve area, higher rate of moderate-severe calcification, lower mean trans-aortic valve gradient and lower left ventricular ejection fraction. In large-annuli SEVs were associated with a lower VARC-2 device success (75.9% vs. 90.6%, P = 0.049) driven by a higher rate of paravalvular valvular leak (PVL) compared to BEVs (20.7% vs. 1.2%, P &lt; 0.001). However, no differences in clinical outcomes were observed according to annular size nor THV type. Conclusions TAVR in BAV patients is feasible irrespective of annular size. However in patients with large aortic annulus SEVs were associated with a significantly higher rate of PVLs compared to BEVs.

Clinical Value of Stress Transaortic Flow Rate During Dobutamine Echocardiography in Reduced Left Ventricular Ejection Fraction, Low-Gradient Aortic Stenosis: A Multicenter Study

Background: Low rest transaortic flow rate (FR) has been shown previously to predict mortality in low-gradient aortic stenosis. However limited prognostic data exists on stress FR during low-dose dobutamine stress echocardiography. We aimed to assess the value of stress FR for the detection of aortic valve stenosis (AS) severity and the prediction of mortality. Methods: This is a multicenter cohort study of patients with reduced left ventricular ejection fraction and low-gradient aortic stenosis (aortic valve area <1 cm 2 and mean gradient <40 mm Hg) who underwent low-dose dobutamine stress echocardiography to identify the AS severity and presence of flow reserve. The outcome assessed was all-cause mortality. Results: Of the 287 patients (mean age, 75±10 years; males, 71%; left ventricular ejection fraction, 31±10%) over a mean follow-up of 24±30 months there were 127 (44.3%) deaths and 147 (51.2%) patients underwent aortic valve intervention. Higher stress FR was independently associated with reduced risk of mortality (hazard ratio, 0.97 [95% CI, 0.94–0.99]; P =0.01) after adjusting for age, chronic kidney disease, heart failure symptoms, aortic valve intervention, and rest left ventricular ejection fraction. The minimum cutoff for prediction of mortality was stress FR 210 mL/s. Following adjustment to the same important clinical and echocardiographic parameters, among the three criteria of AS severity during stress, ie, the guideline definition of aortic valve area <1cm 2 and aortic valve mean gradient ≥40 mm Hg, or aortic valve mean gradient ≥40 mm Hg, or the novel definition of aortic valve area <1 cm 2 at stress FR ≥210 mL/s, only the latter was independently associated with mortality (hazard ratio, 1.72 [95% CI, 1.05–2.82]; P =0.03). Furthermore aortic valve area <1cm 2 at stress FR ≥210 mL/s was the only severe aortic stenosis criterion that was associated with improved outcome following aortic valve intervention ( P <0.001). Guideline-defined stroke volume flow reserve did not predict mortality. Conclusions: Stress FR during low-dose dobutamine stress echocardiography was useful for the detection of both AS severity and flow reserve and was associated with improved prediction of outcome following aortic valve intervention.