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

2021 ◽  
Vol 8 ◽  
Author(s):  
Yogamaya Mantha ◽  
Shutaro Futami ◽  
Shohei Moriyama ◽  
Michinari Hieda
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Ejection Fraction ◽  
Continuous Wave ◽  
Left Ventricular ◽  
Low Flow ◽  
Aortic Valve Area ◽  
Arterial Impedance ◽  
Stenosis Severity ◽  
Lv Ejection Fraction

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.

Abstract 2066: Does Mitral Regurgitation Regress After Aortic Valve Replacement For Aortic Stenosis ? A Prospective Multicenter Study

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Philippe Unger ◽  
Danièle Plein ◽  
Bernard Cosyns ◽  
Guy Van Camp ◽  
Olivier Xhaët ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Mitral Regurgitation ◽  
Aortic Stenosis ◽  
Ejection Fraction ◽  
Aortic Valve Replacement ◽  
Valve Replacement ◽  
Left Ventricular ◽  
Aortic Valve Area ◽  
Regurgitant Volume ◽  
Lv Ejection Fraction

Background: Mitral regurgitation (MR) is common in patients undergoing aortic valve replacement (AVR) for aortic stenosis (AS). Whether its severity may decrease after AVR remains controversial. Previous studies were mainly retrospective and the degree of MR was assessed at best semi-quantitatively. This study sought to prospectively and quantitatively assess how AVR may affect MR severity. Methods: Patients with AS scheduled for isolated AVR and presenting holosystolic MR which was not considered for replacement or repair were included. Previous mitral valve surgery; severe aortic regurgitation and poor acoustic windows were excluded. Thirty-five patients (mean age 77±7 years) were studied before (median 1, range 1– 41 days) and after AVR (median 7, range 4 –19 days). All patients underwent a comprehensive echocardiographic examination; MR was assessed by Doppler echocardiography using color flow mapping of the regurgitant jet and the PISA method. No patient had prolapsed or flail mitral leaflet as mechanism of MR. Results: Preoperative maximal and mean transaortic pressure gradients and aortic valve area were 74±26 mmHg, 44±16 mmHg, and 0.57±0.18 cm 2 , respectively. Left ventricular (LV) ejection fraction increased from 49±16 % to 55±15 % after AVR (p<0.001). LV end-diastolic volume decreased from 91±32 ml to 77±30 ml (p<0.001).The ratio of MR jet to left atrial area decreased from 30±16% to 20±14% (p<0.001). MR effective regurgitant orifice (ERO) and regurgitant volume decreased from 10±5 mm 2 to 8±6 mm 2 (p=0.015) and from 19±10 ml to 11±9 ml (p<0.0001). The decrease in ERO and in regurgitant volume was similar in patients with preserved or depressed LV ejection fraction (≤45 %) (2±3 vs 3±6 mm 2 and 7±9 vs 8±7 ml; p=NS, respectively). Conclusions: AVR is associated with an early postoperative reduction of the quantified degree of MR. This mainly results from a decrease in regurgitant volume and only modestly from a reduction in ERO, emphasizing the contributing role of the decrease in driving pressure accross the mitral regurgitant orifice.

scholarly journals Use of passive leg rise as an add-on to dobutamine in patients with paradoxical low-flow, low-gradient aortic stenosis

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
E Buffle ◽  
A Papadis ◽  
C Seiler ◽  
S F De Marchi
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Ejection Fraction ◽  
Stroke Volume Index ◽  
Left Ventricular ◽  
Low Flow ◽  
Volume Index ◽  
Aortic Valve Area ◽  
Low Ejection Fraction ◽  
Valve Area

Abstract Background Dobutamine has been proposed for the assessment of low-flow, low-gradient aortic stenosis (LFLGAS). However, in 1/3 of patients, no increase in stroke volume index can be achieved by Dobutamine, thus hampering its diagnostic value. This study evaluated the manoeuvre of cardiac preload augmentation by passive leg rise (PLR) alone or on top of Dobutamine to increase stroke volume index (SVI) in patients with LFLGAS, particularly in paradoxical LFLGAS. Methods We examined 50 patients with LFLGAS. Patients were assigned to the paradoxical LFLGAS (Paradox) group if left ventricular ejection fraction (LVEF) was ≥50% (n=29) and to the LFLGAS with low ejection fraction (LEF) group if LVEF was &lt;50% (n=21). A modified Dobutamine stress echocardiography was performed in all patients with the following 4 steps: Rest, PLR alone, maximal Dobutamine infusion rate alone (Dmax) and Dobutamine plus PLR (Dmax + PLR). Three SVI measurement methods were used: first the left ventricular outflow tract velocity time integral (LVOT VTI) method, second the 2D Simpson's method, and third the 3D method. The corresponding aortic valve area (AVA) was obtained by the continuity equation. The increase of those values compared to measurements at rest was calculated and compared between the 3 stress steps. Results In the paradoxical LFLGAS group, delta SVI with Dmax assessed by both Simpson's (depicted in the figures) and 3D method was lowest compared to PLR and Dmax + PLR. PLR alone yielded an equally high delta SVI as Dmax + PLR in Simpson's and 3D, and was at least as high as Dmax across all methods. Dobutamine alone yielded the lowest delta transaortic aortic valve VTI. The highest delta aortic valve area resulted for Dmax + PLR. In the LEF group, the three stress steps yielded an equally high delta SVI with Simpson's method. Dmax never yielded a higher delta SVI than PLR alone. The yielded delta SVI was the highest for Dmax + PLR for both LVOT VTI and 3d method, although the difference was overall not as strong as in the Paradox group. Conclusions In patients with paradoxical LFLGAS, Dobutamine alone is inadequate for testing the potential of aortic valve opening augmentation. Instead, PLR alone or the addition of PLR plus Dobutamine should be used for that purpose. In low LVEF, adding PLR to Dobutamine also seems useful although its diagnostic added value is less evident than in the Paradox group. FUNDunding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Gottfried und Julia Bangerter-Rhyner-Foundation Paradox group Low ejection fraction group

Abstract 5773: Reduced Left Ventricular Vortex Formation Ability Despite Preserved Ejection Fraction in Low-Flow, Low-Gradient Severe Aortic Stenosis

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Li Ching Lee ◽  
Sher Lynn Lim ◽  
Huay Cheem Tan ◽  
Boon Lock Chia ◽  
Kian Keong Poh
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Ejection Fraction ◽  
Severe Aortic Stenosis ◽  
Vortex Formation ◽  
Left Ventricular ◽  
Low Flow ◽  
Aortic Valve Area ◽  
Stroke Work ◽  
Tei Index

Background and Aim : Low-flow, low-gradient (LFLG) severe aortic stenosis (AS) despite preserved left ventricular (LV) ejection fraction (EF) has been associated with more advanced stage of the disease, lower cardiac output (CO) and higher systemic afterload. We aim to characterize the LV performance determinants, including its vortex formation (VF) ability. Methods : Echocardiography was performed in 61 consecutive patients with severe AS (aortic valve area index (AVAI) ≤ 0.6 cm 2 /m 2 ) and preserved LVEF (≥ 50%). In addition to biplane LV measurements, AS severity indices and Tei index were measured. Hemodynamic indices (including systemic vascular resistance (SVR) and valvulo-arterial impedance (VAI)) were calculated. VF index (VFI) was obtained from 4 X (1-β)/πX α 3 X LVEF where β is the fraction of total transmitral diastolic stroke volume (SVol) contributed by atrial contraction (assessed by time velocity integral of the mitral E and A waves) and α is the end diastolic volume (EDV) 1/3 divided by mitral annular diameter during early diastole. Patients were categorized by their LV SVol index (SVI). LFLG group consisted of SVI < 45ml/m 2 . Results : Mean VFI was 2.67±1.1; AVAI, 0.50±0.09 cm 2 /m 2 . Though AVAI was slightly lower in LFLG, dimensionless index and aortic valve resistance were similar and associated with no difference in LV mass and volume between the 2 groups. VFI was significantly reduced in the LFLG, 2.37±0.9 vs 3.12±1.3 ( P =0.01), However other LV functional parameters including Tei index and LVEF were similar (Table ). LFLG was associated with higher SVR and VAI (Table ). In LFLG, the only significant correlates of VFI were SVR (r=0.38), VAI (0.37) and stroke work index (0.36); all P s<0.05. VFI did not correlate to these parameters in the non-LFLG group. Conclusion : In LFLG severe AS, increased afterload and suboptimal LV vortex formation ability contribute to lower CO/SV. VFI provides useful insights in understanding this relatively new entity. Comparison of echocardiographic and haemodynamic data in LFLG and non-LFLG groups

scholarly journals Discordant severity criteria in patients with moderate aortic stenosis: prognostic implications

Open Heart ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. e001639
Author(s):  
Stephan M Pio ◽  
Mohammed R Amanullah ◽  
Steele C Butcher ◽  
Kenny Y Sin ◽  
Nina Ajmone Marsan ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Ejection Fraction ◽  
Stroke Volume Index ◽  
Left Ventricular ◽  
Volume Index ◽  
Aortic Valve Area ◽  
Risk Of Mortality ◽  
Lv Ejection Fraction ◽  
Prognostic Implications

BackgroundThe criteria to define the grade of aortic stenosis (AS)—aortic valve area (AVA) and mean gradient (MG) or peak jet velocity—do not always coincide into one grade. Although in severe AS, this discrepancy is well characterised, in moderate AS, the phenomenon of discordant grading has not been investigated and its prognostic implications are unknown.ObjectivesTo investigate the occurrence of discordant grading in patients with moderate AS (defined by an AVA between 1.0 cm² and 1.5 cm² but with an MG <20 mm Hg) and how these patients compare with those with concordant grading moderate AS (AVA between 1.0 cm² and 1.5 cm² and MG ≥20 mm Hg) in terms of clinical outcomes.MethodsFrom an ongoing registry of patients with AS, patients with moderate AS based on AVA were selected and classified into discordant or concordant grading (MG <20 mm Hg or ≥20 mm Hg, respectively). The clinical endpoint was all-cause mortality.ResultsOf 790 patients with moderate AS, 150 (19.0%) had discordant grading, moderate AS. Patients with discordant grading were older, had higher prevalence of previous myocardial infarction and left ventricular (LV) hypertrophy, larger LV end-diastolic and end-systolic volume index, higher LV filling pressure and lower LV ejection fraction and stroke volume index as compared with their counterparts. After a median follow-up of 4.9 years (IQR 3.0–8.2), patients with discordant grading had lower aortic valve replacement rates (26.7% vs 44.1%, p<0.001) and higher mortality rates (60.0% vs 43.1%, p<0.001) as compared with patients with concordant grading. Discordant grading moderate AS, combined with low LV ejection fraction, presented the higher risk of mortality (HR 2.78 (2.00–3.87), p<0.001).ConclusionDiscordant-grading moderate AS is not uncommon and, when combined with low LV ejection fraction, is associated with high risk of mortality.

High Prevalence of Severe Aortic Stenosis in Low-Flow State Associated With Atrial Fibrillation

2021 ◽  
Author(s):  
Said Alsidawi ◽  
Sana Khan ◽  
Sorin V. Pislaru ◽  
Jeremy J. Thaden ◽  
Edward A. El-Am ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Aortic Valve ◽  
Aortic Stenosis ◽  
Left Ventricular ◽  
Hazard Ratio ◽  
Low Flow ◽  
Left Ventricular Ejection ◽  
Aortic Valve Area ◽  
Flow State ◽  
Ventricular Ejection Fraction

Background: Atrial fibrillation (AF) is a low-flow state and may underestimate aortic stenosis (AS) severity. Single-high Doppler signals (HS) consistent with severe AS (peak velocity ≥4 m/s or mean gradient ≥40 mm Hg) are averaged down in current practice. The objective for the study was to determine the significance of HS in AF low-gradient AS (LGAS). Methods: One thousand five hundred forty-one patients with aortic valve area ≤1 cm 2 and left ventricular ejection fraction ≥50% were identified and classified as high-gradient AS (HGAS) (≥40 mm Hg) and LGAS (<40 mm Hg), and AF versus sinus rhythm (SR). Available computed tomography aortic valve calcium scores (AVCS) were retrieved from the medical record. Outcomes were assessed. Results: Mean age was 76±11 years, female 47%. Mean gradient was 51±12 in SR-HGAS, 48±10 in AF-HGAS, 31±5 in SR-LGAS, and 29±7 mm Hg in AF-LGAS, all P ≤0.001 versus SR-HGAS; HS were present in 33% of AF-LGAS. AVCS were available in 34%. Compared with SR-HGAS (2409 arbitrary units; interquartile range, 1581–3462) AVCS were higher in AF-HGAS (2991 arbitrary units; IQR1978–4229, P =0.001), not different in AF-LGAS (2399 arbitrary units; IQR1817–2810, P =0.47), and lower in SR-LGAS (1593 arbitrary units; IQR945–1832, P <0.001); AVCS in AF-LGAS were higher when HS were present ( P =0.048). Compared with SR-HGAS, the age-, sex-, comorbidity index-, and time-dependent aortic valve replacement-adjusted mortality risk was higher in AF-HGAS (hazard ratio=1.82 [1.40–2.36], P <0.001) and AF-LGAS with HS (hazard ratio=1.54 [1.04–2.26], P =0.03) but not different in AF-LGAS without HS or SR-LGAS (both P =not significant). Conclusions: Severe AS was common in AF-LGAS. AVCS in AF-LGAS were not different from SR-HGAS. AVCS were higher and mortality worse in AF-LGAS when HS were present.

scholarly journals P1370 Correlation of aortic stenosis by integrated transthoracic and transesophageal echocardiography with calcium score

2020 ◽  
Vol 21 (Supplement_1) ◽  
Author(s):  
S Schwartzenberg ◽  
Y Shapira ◽  
M Vaturi ◽  
M Nassar ◽  
A Hamdan ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Stroke Volume Index ◽  
Left Ventricular ◽  
Low Flow ◽  
Volume Index ◽  
Left Ventricular Ejection ◽  
Aortic Valve Area ◽  
Ventricular Ejection Fraction ◽  
Coronary Ct

Abstract Funding Acknowledgements None BACKGROUND Aortic stenosis (AS) classification depends on left-ventricular ejection-fraction (LVEF &lt;≥50%), aortic valve area (AVA&lt;≥1cm2), mean pressure gradient (MG&lt;≥40mmHg), peak velocity&lt;≥400 cm/sec, and stroke-volume index (SVI&lt;≥35ml/m2). Aortic Valve Agatston CT score (AVC) correlates with AS severity by trans-thoracic echo (TTE), but its association with AS severity determined by integrated TTE and TEE is unknown. PURPOSE We investigated correlation of AVC with dichotomous AS grouping by Integrated TTE + TEE vs TTE only. METHODS 64 TAVI candidates underwent sequential TTE and TEE, of which 24 underwent coronary CT within 4 months. Based on recommended conservative vs invasive treatment implication (A/B respectively), AS types were aggregated separately by TTE or Integrated TTE-TEE into two groups: Group-A (Moderate AS and Normal-Flow Low-Gradient), and Group-B (High-Gradient, Low-EF Low-Flow Low-Gradient, and Paradoxical Low-Flow Low-Gradient). Continuous and dichotomous AVC correlation (cutoffs based on guidelines) with echo binary classification was then determined. RESULTS Patients were 81.1(77.3-84.6) years old, 18(48.6%) were women, and had LVEF of 60% (49-65). AVC-score distribution in the two AS A/B Groups by two echo modalities is presented in the boxplot Figure. Only classification by TTE held discriminative accuracy in A/B grouping, with Area-Under-Curve of 0.736 (CI 0.57-0.9), and optimal threshold value of 1946 AU having 77% sensitivity and 74% specificity. Compared with AVC dichotomous classification, integrated TTE + TEE upgraded AS class (from A to B) in 5/6 (83.3%) patients vs 12/18 (66.7%) in which it downgraded AS class from B to A. CONCLUSIONS Aortic valve calcification correlates well with AS class dichotomized by operative implication through conventional TTE but not through integrated TTE + TEE. Our preliminary results appear to be caused by initial selection bias of patients in whom coronary CT performance was deemed to be justified by the treating physician rather than reflect a true better correlation between CT score and AS assessment by TTE vs by integrated TTE + TEE. Abstract P1370 Figure.

scholarly journals Left atrial dynamics in the hemodynamic response during exercise in patients with asymptomatic severe aortic stenosis

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
T Sugimoto ◽  
F Bandera ◽  
G Generati ◽  
E Alfonzetti ◽  
M Guazzi
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Left Atrial ◽  
Cardiopulmonary Exercise Testing ◽  
Left Ventricular ◽  
Low Flow ◽  
Volume Index ◽  
Left Ventricular Ejection ◽  
Aortic Valve Area ◽  
Ventricular Ejection Fraction

Abstract Background The hemodynamic impact of left atrial (LA) dynamics in aortic stenosis (AS) in relation to cardiopulmonary response to exercise has never been studied. We aimed at investigating the link between LA function vs hemodynamics and prognosis in asymptomatic severe AS patients. Methods A total of 106 patients: 76 asymptomatic severe AS patients (aortic valve area (AVA) &lt;1.0 cm2 or AVA index &lt;0.6 cm2/m2) and 30 gender-matched control subjects underwent cardiopulmonary exercise testing combined with Echo-Doppler with assessment of LA strain. AS patients were divided into 4 groups according to peak aortic jet velocity (PV), mean pressure gradient (MPG), stroke volume index (SVI), and left ventricular ejection fraction (LVEF). Results Normal-flow low-gradient AS (NFLG: PV &lt;4 m/s and MPG &lt;40 mmHg, SVI &gt;35ml/m2, LVEF ≥50%, N=23), High-gradient AS (HG: PV ≥4 m/s or MPG ≥40 mmHg, LVEF ≥50%, N=23), Paradoxical low-flow low-gradient AS (PLFLG: PV &lt;4 m/s and MPG &lt;40 mmHg, SVI ≤35ml/m2, LVEF ≥50%, N=18), and Classical low-flow AS (CLF: LVEF &lt;50%, N=12) had a higher LA volume index than Control (Control 22±6, NFLG 38±12*, HG 33±9*, PLFLG 33±11*, and CLF 49±15* ml/m2, *P&lt;0.05 vs Control). In PLFLG and NFLG AS, LA strain at rest (21±9 and 26±13%) and during exercise (26±12 and 31±14%) were decreased compared to Control (37±8% at rest, 43±11% during exercise) but LA strain was increased from rest to exercise (P&lt;0.001). HG and CLF AS had no increase in LA strain (31±15 and 19±10% at rest, 28±15 and 18±9% during exercise) (figure). In Cox proportional hazards analysis, age and gender adjusted hazard ratio for the composite end point (aortic valve replacement, hospitalization for heart failure, and all-cause mortality) of changes in LA-strain from rest to exercise (1% increase) was 1.05 (95% CI 1.00 to 1.09, P=0.044) among AS patients. Conclusions In asymptomatic severe AS, the study of LA functional adaptation to exercise plays a key role in the hemodynamic unfavorable cascade signaling major adaptive differences in dynamics during physical challenge. Overall, LA dynamics provides prognostic information also in AS patients. FUNDunding Acknowledgement Type of funding sources: None.

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

2021 ◽  
Author(s):  
Anastasia Vamvakidou ◽  
Mohamed-Salah Annabi ◽  
Phillipe Pibarot ◽  
Edyta Plonska-Gosciniak ◽  
Ana G. Almeida ◽  
...  
Keyword(s):  
Left Ventricular Ejection Fraction ◽  
Aortic Valve ◽  
Aortic Stenosis ◽  
Ejection Fraction ◽  
Left Ventricular ◽  
Ventricular Ejection ◽  
Left Ventricular Ejection ◽  
Aortic Valve Area ◽  
Ventricular Ejection Fraction ◽  
Valve Area

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.

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