Outcome of Flow-Gradient Patterns of Aortic Stenosis After Aortic Valve Replacement

Normal-Flow Low-Gradient Aortic Stenosis: Comparing the U.S. and European Guidelines

Patients with normal-flow low-gradient (NFLG) severe aortic stenosis present both diagnostic and management challenges, with debate about the whether this represents true severe stenosis and the need for valve replacement. Studies exploring the natural history without intervention have shown similar outcomes of patients with NFLG severe aortic stenosis to those with moderate aortic stenosis and better outcomes after valve replacement than those with low-flow low-gradient severe aortic stenosis. Most studies (all observational) have shown that aortic valve replacement was associated with a survival benefit vs surveillance. Based on available data, the European Society of Cardiology/European Association for Cardio-Thoracic Surgery guidelines and European Association of Cardiovascular Imaging/American Society of Echocardiography suggest that these patients are more likely to have moderate aortic stenosis. This clinical entity is not mentioned in the American Heart Association/American College of Cardiology guidelines. Here we review the definition of NFLG severe aortic stenosis, potential diagnostic algorithms and points of error, the data supporting different management strategies, and the differing guidelines and outline the unanswered questions in the diagnosis and management of these challenging patients.

Patients with paradoxical low-flow, low-gradient aortic stenosis gain the least benefit from TAVI among all hemodynamic subtypes

BACKGROUND

Substantial controversy exists regarding the clinical benefit of patients with severe paradoxical low-flow, low-gradient aortic stenosis (PLF-LG AS) from TAVI. Therefore, we compared post-TAVI benefit by long-term mortality (all-cause, CV and SCD), clinical improvement of heart failure symptoms, and cardiac reverse remodelling in guideline-defined AS subtypes.

METHODS

We prospectively included 250 consecutive TAVI patients. TTE, 6mwt, MLHFQ, NYHA status and NT-proBNP were recorded at baseline and 6 months. Long-term mortality and causes of death were assessed.

RESULTS

107 individuals suffered from normal EF, high gradient AS (NEF-HG AS), 36 from low EF, high gradient AS (LEF-HG), 52 from "classic" low-flow, low-gradient AS (LEF-LG AS), and 38 from paradoxical low-flow, low-gradient AS (PLF-LG AS). TAVI lead to a significant decrease in MLHFQ score and NT-proBNP levels in all subtypes except for PLF-LG. Regarding reverse remodelling, a significant increase in EF and decrease in LVEDV was present only in subtypes with reduced baseline EF, whereas a significant decrease in LVMI and LAVI could be observed in all subtypes except for PLF-LG. During a follow-up of 3-5 years, PLF-LG patients exhibited the poorest survival among all subtypes (HR 4.2, P = 0.0002 for CV mortality; HR 7.3, P = 0.004 for SCD, in comparison with NEF-HG). Importantly, PLF-LG was independently predictive for CV mortality (HR 2.9 [1.3-6.9], P = 0.009).

CONCLUSIONS

PLF-LG patients exhibit the highest mortality (particularly CV and SCD), the poorest symptomatic benefit and the least reverse cardiac remodelling after TAVI among all subtypes. Thus, this cohort seems to gain the least benefit.

Association of atrial fibrillation with survival in patients with low-flow low-gradient aortic stenosis with preserved ejection fraction undergoing TAVI

AIMS

There is limited evidence on the prognostic significance of atrial fibrillation (AF) in patients with low flow, low-gradient aortic stenosis with preserved ejection fraction (LFLG-pEF AS). We aimed to evaluate the recovery of stroke volume after transcatheter aortic valve implantation (TAVI) and clinical outcomes in patients with LFLG-pEF AS stratified by presence or absence of AF.

METHODS AND RESULTS

In a prospective TAVI registry, patients with preserved left ventricular ejection fraction (LVEF ≥ 50%) were stratified according to flow-gradient status and presence of AF. Among 2259 TAVI patients with preserved LVEF between August 2007 and June 2021, 765 had high-gradient AS (HG AS) and 444 had LFLG-pEF AS. AF was observed in 199 patients with HG AS (26.0%) and 190 patients with LFLG-pEF AS (42.8%). At 1 year, stroke volume index (SVi) was significantly improved in LFLG-pEF AS patients without AF, while SVi remained low in patients with AF (from 25.9 ± 8.5 mL/m2 to 37.2 ± 9.9 mL/m2 and from 26.8 ± 5.1 mL/m2 to 26.1 ± 9.1 mL/m2, respectively). LFLG-pEF AS patients with AF had an increased risk of 1-year all-cause mortality compared with those without AF (adjusted hazard ratio (HRadjusted) 2.57; 95% confidence interval [CI] 1.44-4.59). LFLG-pEF AS patients without AF had similar mortality compared with HG AS patients without AF (HRadjusted 0.85; 95% CI 0.49-1.46).

CONCLUSION

Patients with LFLG-pEF AS and AF experienced no relevant recovery of stroke volume after TAVI, but a more than two-fold increased risk of death compared to patients with HG AS or LFLG-pEF AS without AF.

CLINICAL TRIAL REGISTRATION

https://www.clinicaltrials.gov. NCT01368250.

Transcatheter Aortic Valve Replacement Across Hemodynamic Subtypes of Severe Aortic Valve Stenosis: A Network Meta-analysis

Background

Studies assessing outcomes of transcatheter aortic valve replacement (TAVR) in patients with severe aortic valve stenosis (AS) with hemodynamic subtypes have demonstrated mixed results with respect to outcomes and periprocedural complications. This study aimed to assess the outcomes of TAVR in patients across various hemodynamic subtypes of severe AS.

Methods

PubMed, Embase, and Cochrane databases were searched through September 2023 to identify all observational studies comparing outcomes of TAVR in patients with paradoxical low flow low gradient (pLFLG), classic LFLG, and high gradient AS (HGAS). The primary outcome was major adverse cardiovascular events (MACE). The secondary outcomes were components of MACE (mortality, myocardial infarction [MI], stroke). A bivariate, influential, and frequentist network meta-analysis model was used to obtain the net odds ratio (OR) with a 95% CI.

Results

A total of 21 studies comprising 17,298 (8742 experimental and 8556 HGAS) patients were included in the quantitative analysis. TAVR was associated with a significant reduction in the mean aortic gradient, and an increase in the mean aortic valve area irrespective of the AS type. Compared with HGAS, TAVR in classic LFLG had a significantly higher (OR, 1.68; 95% CI, 1.04-2.72), while pLFLG (OR, 0.98; 95% CI, 0.72-1.35) had a statistically similar incidence of MACE at a median follow-up of 1-year. TAVR in LFLG also had a significantly higher need for surgery (OR, 3.57; 95% CI, 1.24-10.32), and a greater risk of periprocedural (OR, 2.00; 95% CI, 1.17-3.41), 1-month (OR, 1.69; 95% CI, 1.08-2.64), and 12-month (OR, 1.41; 95% CI, 1.05-1.88) mortality compared with HGAS. The incidence of MI, major bleeding, vascular complications, paravalvular leak, pacemaker implantation, and rehospitalizations was not significantly different between all other types of AS (HGAS vs LFLG, pLFLG).

Conclusions

TAVR is an effective strategy in severe AS irrespective of the hemodynamic subtypes. Relatively, pLFLG did not have significantly different risk of periprocedural complications compared with HGAS, while classical LFLG AS had higher risk of MACE, primarily driven by the greater mortality risk.

Effect of Sex and Flow Status on Outcomes After Surgical or Transcatheter Aortic Valve Replacement

Background

Low stroke volume index <35 ml/m2 despite preserved ejection fraction (paradoxical low flow [PLF]) is associated with adverse outcomes in patients with aortic stenosis undergoing transcatheter aortic valve replacement (TAVR) or surgical aortic valve replacement (SAVR). However, whether the risk associated with PLF is similar in both sexes is unknown.

Objectives

The purpose of this study was to analyze the risk associated with PLF in severe aortic stenosis for men and women randomized to TAVR or SAVR.

Methods

Patients with ejection fraction ≥50% from the PARTNER (Placement of Aortic Transcatheter Valves) 2 and 3 trials were stratified by sex and treatment arm. The impact of PLF on the 2-year occurrence of the composite of death or heart failure hospitalization (primary endpoint) and of all-cause mortality alone (secondary endpoint) was analyzed. Analysis of variance was used to assess baseline differences between groups. Multivariate Cox regression analysis was used to identify predictors of the endpoint.

Results

Out of 2,242 patients, PLF was present in 390 men and 239 women (30% vs 26%, P = 0.06). PLF was associated with a higher rate of NYHA functional class III to IV dyspnea (60% vs 54%, P < 0.001) and a higher prevalence of atrial fibrillation (39% vs 24%, P < 0.001). PLF was a significant predictor of the primary endpoint among women undergoing SAVR in multivariate analysis (adjusted HR: 2.25 [95% CI: 1.14-4.43], P = 0.02) but was not associated with a worse outcome in any of the other groups (all P > 0.05).

Conclusions

In women with PLF, TAVR may improve outcomes compared to SAVR. PLF appears to have less impact on outcomes in men.

Left ventricular reverse remodeling after transcatheter aortic valve implantation in patients with low-flow low-gradient aortic stenosis

OBJECTIVES

Left ventricular reverse remodeling (LVRR) is associated with improved outcome in patients with heart failure. Factors associated with and predictive of LVRR in patients with low-flow low-gradient aortic stenosis (LFLG AS) after transcatheter aortic valve implantation (TAVI) and its impact on outcome were assessed.

METHODS

Pre- and postprocedural left ventricular (LV) function and volume were investigated in 219 patients with LFLG. LVRR was defined as an absolute increase of ≥10% in LV ejection fraction (LVEF) and reduction of ≥15% in LV end-systolic volume (LVESV). The primary endpoint was the combination of all-cause mortality and rehospitalization for heart failure.

RESULTS

The mean LVEF was 35.0 ± 10.0%, with a stroke volume index (SVI) of 25.9 ± 6.0 mL/m2 and LVESV of 94.04 ± 46.0 mL. At a median of 5.2 months (interquartile range, 2.7-8.1 months), 77.2% (n = 169) of the patients showed echocardiographic evidence of LVRR. A multivariate model revealed three independent factors for LVRR after TAVI: SVI of <25 mL/m2 (hazard ratio [HR], 2.31; 95% confidence interval [CI], 1.08-3.58; p < 0.01), LVEF of <30% (HR, 2.76; 95% CI, 1.53-2.91; p < 0.01), and valvulo-arterial impedance (Zva) of <5 mmHg/mL/m2 (HR, 5.36; 95% CI, 1.80-15.98; p < 0.01). Patients without evidence of LVRR showed a significantly higher incidence of the 1-year combined endpoint (32 [64.0%] vs. 75 [44.4%], p < 0.01).

CONCLUSIONS

The majority of patients with LFLG AS show LVRR after TAVI, which is associated with favorable outcomes. An SVI of <25 mL/m2, LVEF of <30%, and Zva < 5mmHg/mL/m2 represent predictors of LVRR.

Heart Failure after Aortic Valve Replacement: Incidence, Risk Factors, and Implications

Severe aortic stenosis (AS) carries a poor prognosis with the onset of heart failure (HF) symptoms, and surgical or transcatheter aortic valve replacement (AVR) is its only definitive treatment. The management of AS has seen a paradigm shift with the adoption of transcatheter aortic valve replacement (TAVR), allowing for the treatment of AS in patients who would not otherwise be candidates for surgical AVR. Despite improving long-term survival after TAVR in recent years, residual HF symptoms and HF hospitalization are common and are associated with an increased mortality and a poor health status. This review article summarizes the incidence and risk factors for HF after AVR. Strategies for preventing and better managing HF after AVR are necessary to improve outcomes in this patient population. Extensive research is underway to assess whether earlier timing for AVR, prior to the development of severe symptomatic AS and associated extra-valvular cardiac damage, can improve post-AVR patient outcomes.

Cardiac Reversibility and Survival After Transcatheter Aortic Valve Implantation in Patients With Low-Gradient Aortic Stenosis

Background Prognostic implications of transcatheter aortic valve implantation (TAVI) in low-gradient (LG) aortic stenosis (AS) remain controversial. The authors hypothesized that differences in cardiac functional recovery may solve this ongoing controversy. The aim was to evaluate clinical outcomes and the response of left ventricular (LV) function following TAVI in patients with LG AS. Methods and Results This multicenter retrospective study included 1742 patients with severe AS undergoing TAVI between January 2015 and March 2019. Patients were subdivided into low-flow (LF) LG, normal-flow (NF) LG, LF high-gradient, and NF high-gradient AS groups according to the mean gradient of the aortic valve (LG <40 mm Hg) and LV stroke volume index (LF <35 mL/m2). Outcomes and changes in echocardiographic parameters after TAVI were compared between the groups. A total of 227 patients (13%) had reduced ejection fraction, and 486 patients (28%) had LG AS (LF-LG 143 [8%]; NF-LG 343 [20%]). During a median follow-up period of 747 days, 301 patients experienced a composite end point of cardiovascular death and rehospitalization for cardiovascular events, which was higher in the LF-LG and NF-LG groups than in the high-gradient groups. LG AS was independently associated with the primary outcome (hazard ratio, 1.69; P<0.001). Among 1239 patients with follow-up echocardiography, LG AS showed less improvement in the LV mass index and LV end-diastolic volume compared with high-gradient AS after 1 year, while LV recovery was similar between the LF AS and NF AS groups. Conclusions LG AS was associated with poorer outcomes and LV recovery, regardless of flow status after TAVI. Careful evaluation of AS severity may be required in LG AS to provide TAVI within the appropriate time and advanced care afterward.

Aortic Valve Disease, Transcatheter Aortic Valve Replacement, and the Heart Failure Patient: A State-of-the-Art Review

Concomitant aortic stenosis (AS) in heart failure (HF) is associated with high rates of mortality and morbidity. Current guidelines recommend aortic valve replacement in patients with severe symptomatic AS and asymptomatic AS with left ventricular ejection fraction <50% and during other cardiac surgeries. Transcatheter aortic valve replacement (TAVR) has now allowed for the treatment of severe AS in previously inoperable or high-surgical-risk patients. Leveraging multimodality imaging techniques is increasingly recognized for reinforcing the rationale for intervening early, thus mitigating the risk of ongoing progression to advanced HF. There are increasing data in favor of TAVR in diverse clinical scenarios, particularly asymptomatic AS and moderate AS. Limited information is, however, available regarding the advantages of HF medical therapy before and after intervention. This review aims to comprehensively examine the phenotypes of AS in the context of HF progression, while exploring the evolving role of TAVR in specific populations.

Comprehensive myocardial characterization using cardiac magnetic resonance associates with outcomes in low gradient severe aortic stenosis

AIMS

This study sought to compare cardiac magnetic resonance (CMR) characteristics according to different flow/gradient patterns of aortic stenosis (AS) and to evaluate their prognostic value in patients with low-gradient AS.

METHODS AND RESULTS

This international prospective multicentric study included 147 patients with low-gradient moderate to severe AS who underwent comprehensive CMR evaluation of left ventricular global longitudinal strain (LVGLS), extracellular volume fraction (ECV), and late gadolinium enhancement (LGE). All patients were classified as followings: classical low-flow low-gradient (LFLG) [mean gradient (MG) < 40 mmHg and left ventricular ejection fraction (LVEF) < 50%]; paradoxical LFLG [MG < 40 mmHg, LVEF ≥ 50%, and stroke volume index (SVi) < 35 ml/m2]; and normal-flow low-gradient (MG < 40 mmHg, LVEF ≥ 50%, and SVi ≥ 35 ml/m2). Patients with classical LFLG (n = 90) had more LV adverse remodelling including higher ECV, and higher LGE and volume, and worst LVGLS. Over a median follow-up of 2 years, 43 deaths and 48 composite outcomes of death or heart failure hospitalizations occurred. Risks of adverse events increased per tertile of LVGLS: hazard ratio (HR) = 1.50 [95% CI, 1.02-2.20]; P = 0.04 for mortality; HR = 1.45 [1.01-2.09]; P < 0.05 for composite outcome; per tertile of ECV, HR = 1.63 [1.07-2.49]; P = 0.02 for mortality; HR = 1.54 [1.02-2.33]; P = 0.04 for composite outcome. LGE presence also associated with higher mortality, HR = 2.27 [1.01-5.11]; P < 0.05 and composite outcome, HR = 3.00 [1.16-7.73]; P = 0.02. The risk of mortality and the composite outcome increased in proportion to the number of impaired components (i.e. LVGLS, ECV, and LGE) with multivariate adjustment.

CONCLUSIONS

In this international prospective multicentric study of low-gradient AS, comprehensive CMR assessment provides independent prognostic value that is cumulative and incremental to clinical and echocardiographic characteristics.

TAVI in patients with low-flow low-gradient aortic stenosis-short-term and long-term outcomes

OBJECTIVES

The study objective was to characterize different groups of low-flow low-gradient (LFLG) aortic stenosis (AS) and determine short-term outcomes and long-term mortality according to Valve Academic Research Consortium-3 (VARC-3) endpoint definitions.

BACKGROUND

Characteristics and outcomes of patients with LFLG AS undergoing transcatheter aortic valve implantation (TAVI) are poorly understood.

METHODS

All patients undergoing TAVI at our center between 2013 and 2019 were screened. Patients were divided into three groups according to mean pressure gradient (dPmean), ejection fraction (LVEF), and stroke volume index (SVi): high gradient (HG) AS (dPmean ≥ 40 mmHg), classical LFLG (cLFLG) AS (dPmean < 40 mmHg, LVEF < 50%), and paradoxical LFLG (pLFLG) AS (dPmean < 40 mmHg, LVEF ≥ 50%, SVi ≤ 35 ml/m2).

RESULTS

We included 1776 patients (956 HG, 447 cLFLG, and 373 pLFLG patients). Most baseline characteristics differed significantly. Median Society of Thoracic Surgeons (STS) score was highest in cLFLG, followed by pLFLG and HG patients (5.0, 3.9 and 3.0, respectively, p < 0.01). Compared to HG patients, odds ratios for the short-term VARC-3 composite endpoints, technical failure (cLFLG, 0.76 [95% confidence interval, 0.40-1.36], pLFLG, 1.37 [0.79-2.31]) and device failure (cLFLG, 1.06 [0.74-1.49], pLFLG, 0.97 [0.66-1.41]) were similar, without relevant differences within LFLG patients. NYHA classes improved equally in all groups. Compared to HG, LFLG patients had a higher 3-year all-cause mortality (STS score-adjusted hazard ratios, cLFLG 2.16 [1.77-2.64], pLFLG 1.53 [1.22-193]), as well as cardiovascular mortality (cLFLG, 2.88 [2.15-3.84], pLFLG, 2.08 [1.50-2.87]).

CONCLUSIONS

While 3-year mortality remains high after TAVI in LFLG compared to HG patients, symptoms improve in all subsets after TAVI.

Impact of Surgical and Transcatheter Aortic Valve Replacement in Low-Gradient Aortic Stenosis: A Meta-Analysis

OBJECTIVES

The aim of this study was to assess the impact of aortic valve replacement (AVR) on survival in patients with each subclass of low-gradient (LG) aortic stenosis (AS) and to compare outcomes following surgical AVR (SAVR) and transcatheter AVR (TAVR).

BACKGROUND

LG severe AS encompasses a wide variety of pathophysiology, including classical low-flow, LG (LF-LG), paradoxical LF-LG, and normal-flow, LG (NF-LG) AS, and uncertainty exists regarding the impact of AVR on each subclass of LG AS.

METHODS

PubMed and Embase were queried through October 2020 to identify studies comparing survival with different management strategies (SAVR, TAVR, and conservative) in patients with LG AS. Pairwise meta-analysis comparing AVR versus conservative management and network meta-analysis comparing SAVR versus TAVR versus conservative management were performed.

RESULTS

Thirty-two studies with a total of 6,515 patients and a median follow-up time of 24.2 months (interquartile range: 36.5 months) were included. AVR was associated with a significant decrease in all-cause mortality in classical LF-LG (hazard ratio [HR]: 0.42; 95% confidence interval [CI]: 0.36 to 0.48), paradoxical LF-LG (HR: 0.41; 95% CI: 0.29 to 0.57), and NF-LG (HR: 0.41; 95% CI: 0.27 to 0.62) AS compared with conservative management. SAVR and TAVR were each associated with a decrease in all-cause mortality in classical LF-LG (HR: 0.46 [95% CI: 0.38 to 0.55] and 0.49 [95% CI: 0.37 to 0.64], respectively), paradoxical LF-LG (HR: 0.42 [95% CI: 0.28 to 0.65] and 0.42 [95% CI: 0.25 to 0.72], respectively), and NF-LG (HR: 0.40 [95% CI: 0.21 to 0.77] and 0.46 [95% CI: 0.26 to 0.84], respectively) AS compared with conservative management. No significant difference was observed between SAVR and TAVR.

CONCLUSIONS

In all subclasses of LG AS, AVR was associated with a significant decrease in all-cause mortality regardless of surgical or transcatheter approach.

Benefit of Transcatheter Aortic Valve Replacement in Patients With Paradoxical Low-Flow Low-Gradient Versus High-Gradient Aortic Stenosis and Preserved Left Ventricular Function

[Figure: see text].

Predicting and measuring mortality risk after transcatheter aortic valve replacement

Introduction: Over the last decade, transcatheter aortic valve replacement (TAVR) has emerged as a treatment option for most patients with severe symptomatic aortic stenosis (AS). With growing indications and exponential increase in the number of TAVR procedures, it is important to be able to accurately predict mortality after TAVR.Areas covered: Herein, we review the surgical and TAVR-specific mortality prediction models (MPMs) and their performance in their original derivation and external validation cohorts. We then discuss the role of other important risk assessment tools such as frailty, echocardiographic parameters, and biomarkers in patients, being considered for TAVR.Expert opinion: Conventional surgical MPMs have suboptimal predictive performance and are mis-calibrated when applied to TAVR populations. Although a number of TAVR-specific MPMs have been developed, their utility is also limited by their modest discriminative ability when applied to populations external to their original derivation cohorts. There is an unmet need for robust TAVR MPMs that accurately predict post TAVR mortality. In the interim, heart teams should utilize the currently available TAVR-specific MPMs in conjunction with other prognostic factors, such as frailty, echocardiographic or computed tomography (CT) imaging parameters, and biomarkers for risk assessment of patients, being considered for TAVR.

Impact of Left-Ventricular Dysfunction in Patients With High- and Low- Gradient Severe Aortic Stenosis Following Transcatheter Aortic Valve Replacement

BACKGROUND

Outcomes of transcatheter aortic valve replacement (TAVR) in patients with high-gradient (HG) severe aortic stenosis (AS) and reduced left-ventricular (LV) ejection fraction (EF) are unknown.

METHODS

Patients undergoing TAVR for native severe AS between 2009 and 2018 were retrospectively included and classified into 3 groups: HG (≥ 40 mm Hg) and preserved EF (≥ 50%), HG low EF (< 50%), and low gradient (LG < 40 mm Hg) low EF. The primary endpoint was a composite of cardiovascular mortality and readmission for heart failure at 1 year after TAVR.

RESULTS

Of the 526 patients included, 323 (61%) had HG preserved EF, 69 (13%) had HG low EF, and 134 (26%) had LG low EF. HG low EF group had higher prevalence of atrial fibrillation and heart failure and higher Society of Thoracic Surgeons score compared with the HG preserved EF group. Patients in the LG low EF group were older and had higher prevalence of coronary artery disease compared with those in the HG groups. All-cause mortality at 30 days (4.0%) was similar across the 3 groups. After adjustment, the risk of primary endpoint was similar in the HG low-EF vs preserved EF groups. Conversely, the risk of primary endpoint was higher in the LG low EF group vs the HG preserved EF group (hazard ratio [HR], 2.24; 95% confidence interval [CI],1.36-3.70; P = 0.002) and vs HG low EF group (HR, 3.50; 95% CI, 1.55-7.90; P = 0.003), whereas the risk of all-cause mortality was similar across the 3 groups.

CONCLUSIONS

The outcome of patients with HG low EF severe AS following TAVR is as good as that of patients with HG preserved EF.