Normal-flow Low-gradient Aortic Stenosis Research Articles

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

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. 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. 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 35ml/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 43ml/m2. 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.

Prognostic impact of cardiac damage staging classification in each aortic stenosis subtype undergoing TAVI.

The prognostic value of cardiac damage staging classifications across the haemodynamic spectrum of severe aortic stenosis (AS) remains unknown. We aimed to investigate the prognostic impact of cardiac damage staging classifications in patients with high-gradient AS (HG-AS) and low-gradient AS (LG-AS) undergoing transcatheter aortic valve implantation (TAVI). In a prospective TAVI registry, five-year mortality was evaluated for early stages of cardiac damage (stage 0, 1, or 2) and advanced stages of cardiac damage (stage 3 or 4) in patients with HG-AS, classical low-flow (LF) LG-AS, LF LG-AS with preserved ejection fraction (pEF), and normal-flow (NF) LG-AS. Among 2,090 patients undergoing TAVI, 1,045 patients had HG-AS, 337 patients had classical LF LG-AS, 394 patients had LF LG-AS with pEF, and 314 patients had NF LG-AS. The majority of patients with classical LF LG-AS exhibited advanced cardiac damage (73.6%), followed by LF LG-AS with pEF (55.6%), NF LG-AS (51.6%), and HG-AS (50.6%). Patients with advanced stage cardiac damage had significantly higher mortality after TAVI than those with early stage cardiac damage in all subtypes of AS (adjusted hazard ratio [HRadjusted] 1.66, 95% confidence interval [CI]: 1.34-2.06 for HG-AS; HRadjusted 1.49, 95% CI: 1.02-2.16 for classical LF LG-AS; HRadjusted 1.69, 95% CI: 1.22-2.35 for LF LG-AS with pEF; and HRadjusted 1.52, 95% CI: 1.04-2.32 for NF LG-AS). Cardiac damage staging classifications stratified mortality after TAVI irrespective of AS subtype.

Impact of cardiac staging classification in transcatheter aortic valve implantation for major subtypes of severe aortic stenosis

Abstract Background Staging classification to quantify the extent of extra-aortic valve cardiac damage is recognized as a useful prognostic tool in patients undergoing transcatheter aortic implantation (TAVI) for aortic stenosis (AS). However, this classification has not been validated in each AS subtype. Objectives The present study aimed to investigate the prognostic impact of staging classification in patients with four major AS subtypes. Methods In a prospective TAVI registry, patients were classified into high gradient AS (HG-AS), classical low flow low gradient AS (LFLG-AS), paradoxical LFLG-AS, and normal flow low gradient AS (NFLG-AS). Five-year mortality was compared between early stage (stage 0, 1, or 2) and advanced stage (stage 3 or 4). Results Among 1,507 patients undergoing TAVI, 812 patients had HG-AS, 186 patients had classical LFLG-AS, 277 patients had paradoxical LFLG-AS, and 232 patients had NFLG-AS. There were much difference in the distribution of cardiac stage among AS subtypes; advanced stage accounting for 54.3% in HG-AS, 58.6% in NFLG-AS, 62.5% in paradoxical LFLG-AS, and 80.6% in classical LFLG-AS. Patients with advanced stage had higher all-cause mortality compared with early stage in HG-AS and paradoxical LFLG-AS (HRadjusted 2.00; 95% CI 1.44-2.78 and HRadjusted 2.15; 95% CI 1.43-3.21), but not in classical LFLG-AS and NFLG-AS (HRadjusted 1.17; 95% CI 0.70-1.95 and HRadjusted 1.43; 95% CI 0.90-2.27). Conclusions Early stage was associated with a reduced risk for five-year mortality in patients with HG-AS and paradoxical LFLG-AS, while there was comparable mortality between early and advanced stages in patients with classical LFLG-AS and NFLG-AS.

Short-Term Outcomes Following Transcatheter Aortic Valve Implantation: Classical Low-Flow Low-Gradient Versus Normal-Flow Low-Gradient Severe Aortic Stenosis

Background: Both classical severe low-flow low-gradient aortic stenosis (LFLG-AS) and severe normal-flow low-gradient aortic stenosis (NFLG-AS) patients undergo transcatheter aortic valve implantation (TAVI). However, few studies have compared outcomes between the two groups. Our study aimed to assess short term post-TAVI outcomes between classical LFLG-AS and NFLG-AS. Methods: We conducted a retrospective, single-center, analysis of 206 patients who underwent TAVI between January 2011 to September 2020. Of these, 44 (males: 33) had classical LFLG-AS and 162 (males: 89) had NFLG-AS. Six-month primary outcomes included all-cause and cardiovascular mortality. Multiple secondary outcomes were assessed including stroke, myocardial infarction (MI), new-onset atrial fibrillation, acute kidney injury (AKI), major bleeding, vascular complications, and repeat hospitalizations from cardiac causes. Results: The cumulative six-month all-cause and cardiovascular mortality were similar between classical severe LFLG-AS and NFLG-AS patients (6.81 % vs. 4.32 %, P = 0.49 and 2.27 % vs. 2.47 %, P = 0.93 respectively). All secondary outcomes were also similar, except for a statistically significant higher rate of AKI in patients with classical LFLG-AS (P = < 0.0001). Conclusion: Except for a higher incidence of AKI in patients with severe classical LFLG-AS, six-month post-TAVI outcomes did not differ between classical LFLG-AS and NFLG-AS.

Changes in echocardiographic parameters over time in paradoxical low-flow low-gradient aortic stenosis

Abstract Funding Acknowledgements Type of funding sources: None. Background Although paradoxical low-flow low-gradient (LFLG) aortic stenosis (AS) has been considered a more severe form of AS with a worse prognosis than high-gradient (HG) AS, data on the natural history of this entity are scant. Objectives To assess the progression of the disease and evolution of the main echocardiographic variables for quantifying AS in patients with severe LFLG AS compared to HG and normal-flow low-gradient (NFLG) AS. Methods A longitudinal, observational, multicenter study including consecutive asymptomatic patients with severe AS (AVA<1.0cm²) and normal LVEF (≥50%) was conducted. Patients were classified according to baseline echocardiography into one of three groups: HG (mean gradient≥40 mmHg), NFLG (mean gradient<40 mmHg, indexed systolic volume (SVi)>35ml/m²), or LFLG (mean gradient<40mmHg, SVi≤35ml/m²). AS progression was analyzed by comparing patients’ baseline measurements and their last follow-up measurements or those taken prior to aortic valve replacement (AVR). Results Of the 903 included patients, 401 (44.4%) were HG, 405 (44.9%) NFLG, and 97 (10.7%) LFLG. The median total follow-up time was 60.2 months (IQR 44.7–83.4). Progression of the mean gradient in a linear mixed regression model was greater in low-gradient groups: LFLG vs. HG (regression coefficient 0.124, p = 0.005) and NFLG vs. HG (regression coefficient 0.068, p = 0.018). No differences were observed between the LFLG and NFLG groups (regression coefficient 0.056, p = 0.195). However, aortic valve area (AVA) reduction was slower in the LFLG group compared to the NFLG (p<0.001). During follow-up, 19.1% (n=9) of LFLG patients evolved to having NFLG AS and 44.7% (n=21) to having HG AS. 58.0% of patients underwent AVR with HG AS (n=29). Conclusions LFLG AS shows an intermediate AVA and gradient progression compared to NFLG and HG AS. The majority of patients initially classified as having LFLG AS changed over time to having other severe forms of AS, and most of them received AVR with HG AS.

Quantification of Significant Aortic Stenosis by Echocardiography versus Four-Dimensional Cardiac Computed Tomography: A Multi-Modality Imaging Study.

Transthoracic echocardiography (TTE) grading of aortic stenosis (AS) is challenging when parameters are discrepant, and four-dimensional cardiac computed tomography (4D-CCT) is increasingly utilized for transcatheter intervention workup. We compared TTE and 4D-CCT measures contributing to AS quantification. AS patients (n = 80, age 86 ± 10 years, 71% men) referred for transcatheter replacement in 2014-2017 were retrospectively studied, 20 each with high-gradient AS (HG-AS), classical and paradoxical low-flow low-gradient AS (CLFLG-AS and PLFLG-AS), and normal-flow low-gradient AS (NFLG-AS). Correlation and Bland-Altman analyses were performed between TTE and 4D-CCT parameters. There were moderate-to-high TTE versus 4D-CCT correlations for left ventricular volumes, function, mass, and outflow tract dimensions (r = 0.51-0.88), though values were mostly significantly higher by 4D-CCT (p < 0.001). Compared with 4D-CCT planimetry of aortic valve area (AVA), TTE estimates had modest correlation (r = 0.37-0.43) but were significantly lower (by 0.15-0.32 cm2). The 4D-CCT estimate of LVSVi lead to significant reclassification of AS subtype defined by TTE. In conclusion, 4D-CCT quantified values were higher than TTE for the left ventricle and AVA, and the AS subtype was reclassified based on LVSVi by 4D-CCT, warranting further research to establish its clinical implications and optimal thresholds in severe AS management.

Abstract 12772: Transcatheter Aortic Valve Replacement Improves Functional and Quality Of Life Outcomes in Patients With Low Gradient Aortic Stenosis

Introduction: Aortic stenosis (AS) is the most common valvular disease, and severe disease can significantly impact morbidity. Less data exists examining the functional and quality of life (QOL) effects of transcatheter aortic valve replacement (TAVR) in patients with severe low-gradient AS in both low-flow and normal-flow states. Hypothesis: Patients with symptomatic, severe, low-gradient AS would have improvements in functional and QOL outcomes at 30-days and 1-year following TAVR procedures. Methods: A single center, retrospective study examined symptomatic, severe, low-gradient AS variants. These had an aortic valve area of ≤1.0 cm 2 , mean transvalvular gradient <40 mmHg, and peak aortic valve velocity of <4 m/s. Classical low-flow low-gradient (CLFLG) AS was defined as a left ventricular ejection fraction (LVEF) <50%. CLFLG group underwent dobutamine stress echo to assess AS severity (Stage D2). Paradoxical low-flow low-gradient (PLFLG) AS was defined as LVEF ≥50% and a stroke volume index (SVi) ≤35mL/m 2 (Stage D3). Normal-flow low-gradient (NFLG) AS was defined as LVEF ≥50% and SVi >35mL/m 2 (Stage D4). The primary outcome was change in New York Heart Association (NYHA) classification and a 12-item Kansas City Cardiomyopathy Questionnaire overall score (KCCQ-OS) at 30-days and 1-year following TAVR. Results: A total of 191 patients were included for analysis: 46 CLFLG, 83 PLFLG, and 62 NFLG AS. At baseline, 130 (68%) had NYHA class III or IV symptoms. Mean baseline KCCQ-OS for all groups was 38±23 (Figure 1). The mean KCCQ-OS at 30-days and 1 year were 62±22 and 68±20. There were no significant differences in KCCQ-OS between the groups at 30-days and 1-year. Following TAVR, 92% and 88% of the cohort had NYHA class I or II symptoms at 30-days and 1 year. Conclusions: Patients with symptomatic, severe low-gradient AS had significant and sustained improvements in their functional and QOL metrics at 30-days and 1-year following TAVR procedures regardless of flow-state.

Quantification of physical activity with activity tracking after transfemoral aortic valve replacement (TAVR)

Abstract Background and hypothesis TAVR is a well-established, safe and effective therapy for severe symptomatic aortic stenosis (AS), but improvement of physical activity after TAVR is difficult to assess objectively. The aim of this study was to quantify improvement of physical activity with Activity Tracking after TAVR with special focus on the different low-gradient subtypes of AS. Methods All patients who underwent TAVR for severe AS in our center between 01/2019 and 12/2019 were screened. Participants received an Activity Tracker for 7 days at two times: after hospital discharge following TAVR procedure and 6 months thereafter. The difference of mean daily steps was defined as study endpoint. Results The analysis is based on 230 patients. The median age was 79.7 years with 53.7% male participants. The median aortic valve area (AVA) was 0.75 cm2 and median mean pressure gradient was 38.7 mmHg (Table 1). The median amount of daily steps was 4409 [IQR 2581–7487] steps/day after hospital discharge and 5326 [IQR 3045–8668] steps/day 6 months thereafter. On a patient base, median difference of steps per day was Δ 529 [IQR −702–2152]). Whenever possible, patients were categorized into different subgroups of AS. Patients with high-gradient (HG) AS showed significant improvement in difference of daily steps at 6 months-FUP (Δ 951 [IQR −378–2.323], p<0.001), as well as patients with paradox low-flow-low-gradient (LFLG) AS (Δ 1392 [IQR −609–4444], p=0.02). Patients with classical LFLG AS also showed an improvement of daily steps at 6-months-FUP but without statistical significance (Δ 192 [IQR −687–770], p=0.79). Patients with a normal-flow-low-gradient (NFLG) AS have no significant difference in daily steps after 6-months and show a tendency of decline in daily steps at 6-months-FUP (Δ −300 [IQR −1334–1406], p=0.67) (Figure 1). Conclusions This is the first study of this sample size to evaluate physical activity after TAVR with an objective and reproducible method. Overall, physical activity improved significantly 6 months after TAVR and daily steps per day increased in all subtypes of AS besides NFLG AS, where a tendency of decline in daily steps without statistical significance was shown. However the increase in daily steps did not reach statistical significance in classical LFLG AS patients. Funding Acknowledgement Type of funding sources: None. Table 1Figure 1

What Is New in Low Gradient Aortic Stenosis: Surgery, TAVR, or Medical Therapy?

A significant proportion of patients with aortic stenosis (AS) have discordance in severity by mean gradient/peak velocity and aortic valve area. Low gradient aortic stenosis (LG-AS) is defined when the aortic valve area is < 1cm2 consistent with severe AS and mean aortic gradient is < 40mmHg consistent with non-severe AS. LG-AS represents a diagnostic and therapeutic challenge. To summarize the different categories, diagnosis, management, and prognosis of LG-AS. LG-AS is classified as classical (ejection fraction (EF) < 50%, indexed stroke volume (SVi) < 35ml/m2), paradoxical (EF > 50%, SVi < 35ml/m2), pseudo-severe (moderate AS with reduced EF), or normal flow low gradient AS. Recent findings emphasize the importance of low-dose dobutamine stress echocardiography and CT calcium score in the assessment of aortic valve. In addition, flow reserve (increase in SV > 50%) can be evaluated during dobutamine stress echocardiography and helps predict perioperative prognosis. Patients with LG-AS have better survival with aortic valve replacement (AVR) compared to medical therapy, irrespective of presence or absence of flow reserve. Some recent studies suggest that transcatheter aortic valve replacement (TAVR) may be superior to surgical AVR for patients with a lack of contractile flow reserve or those with paradoxical LG-AS, but further investigation is needed to clarify optimal treatment. The role of TAVR in patients with moderate AS and reduced EF is also under investigation.

Discordant echocardiographic grading in low gradient aortic stenosis (DEGAS study) from the Italian society of echocardiography and cardiovascular imaging research network: Rationale and study design

Background:Low-gradient aortic stenosis (LG-AS) is characterized by the combination of an aortic valve area compatible with severe stenosis and a low transvalvular mean gradient with low-flow state (i.e., indexed stroke volume <35 mL/m2) in the presence of reduced (classical low-flow AS) or preserved (paradoxical low-flow AS) ejection fraction. Furthermore, the occurrence of a normal-flow LG-AS is still advocated by many authors. Within this diagnostic complexity, the diagnosis of severe AS remains challenging.Objective:The general objective of the Discordant Echocardiographic Grading in Low-gradient AS (DEGAS Study) study will be to assess the prevalence of true severe AS in this population and validate new parameters to improve the assessment and the clinical decision-making in patients with LG-AS.Methods and Analyses:The DEGAS Study of the Italian Society of Echocardiography and Cardiovascular Imaging is a prospective, multicenter, observational diagnostic study that will enroll consecutively adult patients with LG-AS over 2 years. AS severity will be ideally confirmed by a multimodality approach, but only the quantification of calcium score by multidetector computed tomography will be mandatory. The primary clinical outcome variable will be 12-month all-cause mortality. The secondary outcome variables will be (i) 30-day mortality (for patients treated by Surgical aortic valve replacement or TAVR); (ii) 12-month cardiovascular mortality; (iii) 12-month new major cardiovascular events such as myocardial infarction, stroke, vascular complications, and rehospitalization for heart failure; and (iv) composite endpoint of cardiovascular mortality and hospitalization for heart failure. Data collection will take place through a web platform (REDCap), absolutely secure based on current standards concerning the ethical requirements and data integrity.

Low-gradient aortic stenosis.

An important proportion of patients with aortic stenosis (AS) have a 'low-gradient' AS, i.e. a small aortic valve area (AVA <1.0 cm(2)) consistent with severe AS but a low mean transvalvular gradient (<40 mmHg) consistent with non-severe AS. The management of this subset of patients is particularly challenging because the AVA-gradient discrepancy raises uncertainty about the actual stenosis severity and thus about the indication for aortic valve replacement (AVR) if the patient has symptoms and/or left ventricular (LV) systolic dysfunction. The most frequent cause of low-gradient (LG) AS is the presence of a low LV outflow state, which may occur with reduced left ventricular ejection fraction (LVEF), i.e. classical low-flow, low-gradient (LF-LG), or preserved LVEF, i.e. paradoxical LF-LG. Furthermore, a substantial proportion of patients with AS may have a normal-flow, low-gradient (NF-LG) AS: i.e. a small AVA-low-gradient combination but with a normal flow. One of the most important clinical challenges in these three categories of patients with LG AS (classical LF-LG, paradoxical LF-LG, and NF-LG) is to differentiate a true-severe AS that generally benefits from AVR vs. a pseudo-severe AS that should be managed conservatively. A low-dose dobutamine stress echocardiography may be used for this purpose in patients with classical LF-LG AS, whereas aortic valve calcium scoring by multi-detector computed tomography is the preferred modality in those with paradoxical LF-LG or NF-LG AS. Although patients with LF-LG severe AS have worse outcomes than those with high-gradient AS following AVR, they nonetheless display an important survival benefit with this intervention. Some studies suggest that transcatheter AVR may be superior to surgical AVR in patients with LF-LG AS.

Outcome and Impact of Aortic Valve Replacement in Patients With Preserved LVEF and Low-Gradient Aortic Stenosis

BackgroundLow mean transvalvular gradient (<40 mm Hg) and small aortic valve area (<1.0 cm2) in patients with aortic stenosis (AS) and preserved left ventricular ejection fraction raises uncertainty about the actual severity of the stenosis and survival benefit of aortic valve replacement (AVR). ObjectivesThis study analyzed studies of mortality and survival impact of AVR in patients with low-gradient (LG) AS and preserved left ventricular ejection fraction, including paradoxical low-flow (i.e., stroke volume index <35 ml/m2), low-gradient (LF-LG) and normal-flow, low-gradient (NF-LG), and those with high-gradient (≥40 mm Hg) AS or moderate AS. MethodsStudies published between 2005 and 2015 were analyzed. Primary outcome was the survival benefit associated with AVR. Secondary outcome was overall mortality regardless of treatment. ResultsEighteen studies were included in the analysis. Patients with LF-LG AS have increased mortality compared with patients with moderate AS (hazard ratio [HR]: 1.68; 95% confidence interval [CI]: 1.31 to 2.17), NF-LG (HR: 1.80; 95% CI: 1.29 to 2.51), and high-gradient (HR: 1.67; 95% CI: 1.16 to 2.39) AS. AVR was associated with reduced mortality in patients with LF-LG (HR: 0.44; 95% CI: 0.25 to 0.77). Similar benefit occurred with AVR in patients with NF-LG (HR: 0.48; 95% CI: 0.28 to 0.83). Compared with patients with high-gradient AS, those with LF-LG were less likely to be referred to AVR (odds ratio: 0.32; 95% CI: 0.21 to 0.49). ConclusionsPatients with paradoxical LF-LG AS and NF-LG AS have increased risk of mortality compared with other subtypes of AS with preserved left ventricular ejection fraction, and improved outcome with AVR.

Abstract 19826: Utility of Stroke Volume Index for Stratification of Patients With Low Gradient Severe Aortic Stenosis and Normal Left Ventricular Ejection Fraction

Background: Decision of intervention for low gradient severe aortic stenosis (AS) with normal left ventricular ejection fraction (LVEF) is clinically challenging. The study was to determine the impact of stroke volume index (SVi) on prognosis in patients (pts) with AS. Methods: We examined 410 pts with moderate or severe AS and normal EF (≥50%). Pts were divided into four groups based on aortic valve area (AVA), mean pressure gradient (MPG) and SVi: Group I: low flow low gradient severe AS (AVA≤1.0cm 2 , MPG&lt;40mmHg and SVi&lt;35mL/m 2 , n=75); Group II: normal flow low gradient severe AS (AVA≤1.0cm 2 , MPG&lt;40mmHg and SVi≥35mL/m 2 , n=97); Group III: severe AS with matched gradient-AVA (AVA≤1.0cm 2 and MPG≥40mmHg, n=88); Group IV: moderate AS (AVA&gt;1.0cm 2 and MPG&gt;20mmHg, &lt;40 mmHg, n=150). Aortic valve gradients, AVA and SVi were assessed by echocardiography. Clinical charts were reviewed. Mean follow-up duration was 3.2±1.6 years. Results: Group I had higher prevalence of atrial fibrillation, more pronounced LV hypertrophy, lower SVi, smaller AVA, higher valvuloarterial impedance (Zva) (Table) and lower 3-year cumulative survival compared to Group II and Group IV (61% vs. 75% and 80%, p=0.004). Group II had a 3-year cumulative survival similar to moderate AS (75% vs. 80%, p&gt;0.05). In pts with medical management, Group I and Group III had lower 3-year cumulative survival in comparison with Group II and Group IV (48% and 56% vs. 73% and 76%, p=0.001). Multivariate analysis showed SVi was a strong predictor of mortality in low gradient severe AS (HR 0.95, CI: 0.91-0.99, P=0.02). However, in gradient-AVA matched severe AS and moderate AS, SVi was not associated with mortality (p&gt;0.05). Conclusions: Without AS intervention, low flow low gradient severe AS with normal EF carries poor prognosis similar to high gradient AS, but normal flow low gradient AS does not, suggesting that SVi may be used to identify the pts benefiting most from AS intervention in pts with low gradient AS.

Low-Flow, Low-Gradient Severe Aortic Stenosis Despite Normal Ejection Fraction Is Associated With Severe Left Ventricular Dysfunction as Assessed by Speckle-Tracking Echocardiography

Low-flow low-gradient (LFLG) is sometimes observed in severe aortic stenosis (AS) despite normal ejection fraction, but its frequency and mechanisms are still debated. We aimed to describe the characteristics of patients with LFLG AS and assess the presence of longitudinal left ventricular dysfunction in these patients. In a multicenter prospective study, 340 consecutive patients with severe AS and normal ejection fraction were studied. Longitudinal left ventricular function was assessed by 2D-strain and global afterload by valvulo-arterial impedance. Patients were classified according to flow and gradient: low flow was defined as a stroke volume index ≤35 mL/m(2), low gradient as a mean gradient ≤40 mm Hg. Most patients (n=258, 75.9%) presented with high-gradient AS, and 82 patients (24.1%) with low-gradient AS. Among the latter, 52 (15.3%) presented with normal flow and low gradient and 30 (8.8%) with LFLG. As compared with normal flow and low gradient, patients with LFLG had more severe AS (aortic valve area=0.7±0.12 cm(2) versus 0.86±0.14 cm(2)), higher valvulo-arterial impedance (5.5±1.1 versus 4±0.8 mm Hg/mL/m(2)), and worse longitudinal left ventricular function (basal longitudinal strain=-11.6±3.4 versus -14.8±3%; P<0.001 for all). LFLG AS is observed in 9% of patients with severe AS and normal ejection fraction and is associated with high global afterload and reduced longitudinal systolic function. Patients with normal-flow low-gradient AS are more frequent and present with less severe AS, normal afterload, and less severe longitudinal dysfunction. Severe left ventricular longitudinal dysfunction is a new explanation to the concept of LFLG AS.