Left Ventricular Global Longitudinal Strain in Patients with Moderate Aortic Stenosis

Moderate Aortic Stenosis-Advanced Imaging, Risk Assessment, and Treatment Strategies

Moderate aortic stenosis is increasingly recognized as a disease entity with poor prognosis. Diagnosis of moderate aortic stenosis may be complemented by laboratory tests and advanced imaging techniques focused at detecting signs of cardiac damage such as increase of cardiac enzymes (N-terminal pro-B-type Natriuretic Peptide, troponin), left ventricular remodeling (hypertrophy, reduced left ventricular ejection fraction), or myocardial fibrosis. Therapy should include guideline-directed optimal medical therapy for heart failure. Patients with signs of cardiac damage may benefit from early intervention, which is the focus of several ongoing randomized controlled trials. As yet, no evidence-based therapy exists to halt the progression of aortic valve calcification.

Prognostic value of extraaortic-valvular cardiac damage in patients with moderate aortic stenosis and reduced left ventricular ejection fraction

PURPOSE

The extraaortic-valvular cardiac damage (EVCD) Stage has shown potential for risk stratification for patients with aortic stenosis (AS). This study aimed to examine the usefulness of the EVCD Stage in risk stratification of patients with moderate AS and reduced left ventricular ejection fraction (LVEF).

METHODS

Clinical data from patients with moderate AS (aortic valve area, .60-.85 cm2/m2; peak aortic valve velocity, 2.0-4.0 m/s) and reduced LVEF (LVEF 20%-50%) were analyzed during 2010-2019. Patients were categorized into three groups: EVCD Stages 1 (LV damage), 2 (left atrium and/or mitral valve damage), and 3/4 (pulmonary artery vasculature and/or tricuspid valve damage or right ventricular damage). The primary endpoint included a composite of cardiac death and heart failure hospitalization, with non-cardiac death as a competing risk.

RESULTS

The study included 130 patients (mean age 76.4 ± 6.8 years; 62.3% men). They were categorized into three groups: 26 (20.0%) in EVCD Stage 1, 66 (50.8%) in Stage 2, and 48 (29.2%) in Stage 3/4. The endpoint occurred in 54 (41.5%) patients during a median follow-up of 3.2 years (interquartile range, 1.4-5.1). Multivariate analysis indicated EVCD Stage 3/4 was significantly associated with the endpoint (hazard ratio 2.784; 95% confidence interval 1.197-6.476; P = .017) compared to Stage 1, while Stage 2 did not (hazard ratio 1.340; 95% confidence interval .577-3.115; P = .500).

CONCLUSION

The EVCD staging system may aid in the risk stratification of patients with moderate AS and reduced LVEF.

Multimodality Imaging in Aortic Stenosis: Beyond the Valve - Focusing on the Myocardium

Current guidelines of aortic stenosis (AS) management focus on valve parameters, LV systolic dysfunction, and symptoms; however, emerging data suggest that there may be benefit of aortic valve replacement before it becomes severe by present criteria. Myocardial assessment using novel multimodality imaging techniques exhibits subclinical myocardial injury and remodeling at various stages before guideline-directed interventions, which predicts adverse outcomes. This raises the question of whether implementing serial myocardial assessment should become part of the standard appraisal, thereby identifying high-risk patients aiming to minimize adverse outcomes.

Sex Differences in Aortic Stenosis: From the Pathophysiology to the Intervention, Current Challenges, and Future Perspectives

Calcific aortic stenosis (AS) is a major cause of morbidity and mortality in high-income countries. AS presents sex-specific features impacting pathophysiology, outcomes, and management strategies. In women, AS often manifests with a high valvular fibrotic burden, small valvular annuli, concentric left ventricular (LV) remodeling/hypertrophy, and, frequently, supernormal LV ejection fraction coupled with diastolic dysfunction. Paradoxical low-flow low-gradient AS epitomizes these traits, posing significant challenges post-aortic valve replacement due to limited positive remodeling and significant risk of patient-prosthesis mismatch. Conversely, men present more commonly with LV dilatation and dysfunction, indicating the phenotype of classical low-flow low-gradient AS, i.e., with decreased LV ejection fraction. However, these distinctions have not been fully incorporated into guidelines for AS management. The only treatment for AS is aortic valve replacement; women are frequently referred late, leading to increased heart damage caused by AS. Therefore, it is important to reassess surgical planning and timing to minimize irreversible cardiac damage in women. The integrity and the consideration of sex differences in the management of AS is critical. Further research, including sufficient representation of women, is needed to investigate these differences and to develop individualized, sex-specific management strategies.

Prognostic value of left ventricular and left atrial strain imaging in moderate to severe aortic stenosis: Insights from an Asian population

BACKGROUND

Data regarding the prognostic value of left atrial (LA) strain in aortic stenosis (AS) is scarce, especially in Asian population and moderate AS.

METHOD

Left ventricular global longitudinal strain (LVGLS), LA reservoir strain (LASr), conduit strain (LAScd), and contractile strain (LASct) were measured using automated speckle-tracking echocardiography in consecutive patients with moderate or severe AS. The primary endpoint was a composite of all-cause death (ACD) and major adverse cardiovascular events (MACE; myocardial infarction, syncope, and heart failure hospitalization).

RESULTS

Of 712 patients (mean age, 78 ± 12 years; 370 [52%] moderate AS; 342 [48%] severe AS), average LV ejection fraction (LVEF) was 68 with SD of 12%. At a median follow-up of 18 months (interquartile range, 11-26 months), the primary endpoint occurred in 93 patients (60 deaths and 35 MACEs) and 221 patients underwent surgical or transcatheter aortic valve replacement (AVR). In the entire cohort, separate multivariable models adjusted for age, Charlson index, symptomatic status, time-dependent AVR, AS-severity, LA volume index and LVEF demonstrated that only LASr was associated with MACE+ACD (Hazard ratio, 0.97; P = 0.014). Subgroup analysis for MACE+ACD demonstrated consistent prognostication for LASr in moderate and severe AS; LVGLS was prognostic only in severe AS (all P ≤ 0.023). The optimal MACE+ACD cutoff for LASr from spline curves was 21.3%. Adjusted Kaplan-Meier curves demonstrated better event-free survival in patients with LASr >21.3% versus those with LASr ≤21.3% (P = 0.04).

CONCLUSIONS

In both moderate and severe AS, only LASr robustly predicted outcomes; thus, including LASr in the AS staging algorithm should be considered.

Asymptomatic Aortic Stenosis: From Risk Stratification to Treatment

Our understanding of the natural history of aortic stenosis has significantly increased over the last decade. There have been considerable advances in the diagnosis and risk stratification of patients with aortic stenosis and in surgical and anesthetic techniques. In addition, transcatheter aortic valve replacement has established itself as a viable alternative to surgical management. Inevitably, these developments have raised questions regarding the merits of waiting for symptom onset in asymptomatic patients with severe aortic stenosis before offering treatment. Recent observational and randomized trial data suggest that early intervention in asymptomatic patients with severe aortic stenosis and normal left ventricular function may confer a prognostic advantage to a watchful waiting strategy. In this review, we highlight advances in the management and risk stratification of patients with asymptomatic severe aortic stenosis with particular consideration of recent findings supporting early valvular intervention.

Moderate aortic stenosis in the dysfunctional ventricle: should it be treated?

Moderate aortic stenosis is associated with a worse prognosis than milder degrees. Pathophysiologically, this condition in a dysfunctional ventricle could lead to a further mechanism of haemodynamic worsening, so its treatment should lead to clinical advantages for the patient. The low risk of complications associated with percutaneous correction of aortic valve disease (transcatheter aortic valve implantation) should also be considered, which would seem to favour an interventional approach even in the aforementioned condition. However, sparse data and small population studies make this approach still controversial. Three randomized controlled trials are underway to shed definitive light on the topic.

Strain Assessment in Aortic Stenosis: Pathophysiology and Clinical Utility

Contemporary echocardiographic criteria for grading aortic stenosis severity have remained relatively unchanged, despite significant advances in noninvasive imaging techniques over the last 2 decades. More recently, attention has shifted to the ventricular response to aortic stenosis and how this might be quantified. Global longitudinal strain, semiautomatically calculated from standard two-dimensional echocardiographic images, has been the focus of extensive research. Global longitudinal strain is a sensitive marker of subtle hypertrophy-related impairment in left ventricular function and has shown promise as a relatively robust prognostic marker, both independently and when added to severity classification systems. Herein we review the pathophysiological basis underpinning the potential utility of global longitudinal strain in the assessment of aortic stenosis, as well as its potential role in quantifying myocardial recovery and prognostic discrimination following aortic valve replacement.

Multimodality Imaging in Aortic Stenosis: Beyond the Valve - Focusing on the Myocardium

Current guidelines of aortic stenosis (AS) management focus on valve parameters, LV systolic dysfunction, and symptoms; however, emerging data suggest that there may be benefit of aortic valve replacement before it becomes severe by present criteria. Myocardial assessment using novel multimodality imaging techniques exhibits subclinical myocardial injury and remodeling at various stages before guideline-directed interventions, which predicts adverse outcomes. This raises the question of whether implementing serial myocardial assessment should become part of the standard appraisal, thereby identifying high-risk patients aiming to minimize adverse outcomes.

Prognostic Relevance of Global Myocardial Work Index in Patients with Moderate Aortic Valve Stenosis

BACKGROUND

A reduced global myocardial work index (GWI) ≤ 1951 mmHg% is associated with increased mortality in patients with severe aortic valve stenosis (AS). However, parameters predicting the outcome in patients with moderate AS are limited. Therefore, the aim of this study was to evaluate the prognostic value of the GWI in patients with moderate AS.

METHODS AND RESULTS

In this prospective study, 103 patients with moderate AS (mean age 72 ± 10 years; male: 69%) underwent standardized transthoracic echocardiography. The primary endpoint was survival without an aortic valve replacement (AVR). After a median follow-up of 30 ± 5 months, 37 patients (36%) were referred for an AVR. Survival without an AVR was 96% at 12 months and 80% at 30 months (>1951 mmHg%) versus 96% and 68% (≤1951 mmHg%). A GWI ≤ 1951 mmHg% did not predict the need for an AVR (hazard ratio 1.31 (95% CI, 0.63-2.72), p = 0.49). Furthermore, there was no significant correlation between the mean GWI (1644 ± 448 mmHg%) and mean aortic valve pressure gradient (24.2 mmHg ± 6.2, p = 0.615) or effective aortic orifice area (1.24 cm2 ± 0.11, p = 0.678). There was no difference between the AVR and non-AVR groups in the occurrence of clinical symptoms.

CONCLUSION

In contrast to patients with severe AS, a GWI ≤ 1951 mmHg% did not predict the need for an AVR. Further research is needed to improve the risk stratification in patients with moderate AS.

Multimodality Imaging in Aortic Stenosis: Beyond the Valve - Focusing on the Myocardium

Current guidelines of aortic stenosis (AS) management focus on valve parameters, LV systolic dysfunction, and symptoms; however, emerging data suggest that there may be benefit of aortic valve replacement before it becomes severe by present criteria. Myocardial assessment using novel multimodality imaging techniques exhibits subclinical myocardial injury and remodeling at various stages before guideline-directed interventions, which predicts adverse outcomes. This raises the question of whether implementing serial myocardial assessment should become part of the standard appraisal, thereby identifying high-risk patients aiming to minimize adverse outcomes.

Machine learning prediction of progressive subclinical myocardial dysfunction in moderate aortic stenosis

Background

Moderate severity aortic stenosis (AS) is poorly understood, is associated with subclinical myocardial dysfunction, and can lead to adverse outcome rates that are comparable to severe AS. Factors associated with progressive myocardial dysfunction in moderate AS are not well described. Artificial neural networks (ANNs) can identify patterns, inform clinical risk, and identify features of importance in clinical datasets.

Methods

We conducted ANN analyses on longitudinal echocardiographic data collected from 66 individuals with moderate AS who underwent serial echocardiography at our institution. Image phenotyping involved left ventricular global longitudinal strain (GLS) and valve stenosis severity (including energetics) analysis. ANNs were constructed using two multilayer perceptron models. The first model was developed to predict change in GLS from baseline echocardiography alone and the second to predict change in GLS using data from baseline and serial echocardiography. ANNs used a single hidden layer architecture and a 70%:30% training/testing split.

Results

Over a median follow-up interval of 1.3 years, change in GLS (≤ or >median change) could be predicted with accuracy rates of 95% in training and 93% in testing using ANN with inputs from baseline echocardiogram data alone (AUC: 0.997). The four most important predictive baseline features (reported as normalized % importance relative to most important feature) were peak gradient (100%), energy loss (93%), GLS (80%), and DI < 0.25 (50%). When a further model was run including inputs from both baseline and serial echocardiography (AUC 0.844), the top four features of importance were change in dimensionless index between index and follow-up studies (100%), baseline peak gradient (79%), baseline energy loss (72%), and baseline GLS (63%).

Conclusions

Artificial neural networks can predict progressive subclinical myocardial dysfunction with high accuracy in moderate AS and identify features of importance. Key features associated with classifying progression in subclinical myocardial dysfunction included peak gradient, dimensionless index, GLS, and hydraulic load (energy loss), suggesting that these features should be closely evaluated and monitored in AS.

Prognostic value of echocardiographic evaluation of cardiac mechanics in patients with aortic stenosis and preserved left ventricular ejection fraction

Left ventricular ejection function (LVEF) is not reliable in identifying subtle systolic dysfunction. Speckle Tracking (ST) plays a promising role and hemodynamic forces (HDFs) are emerging as marker of LV function. The role of LV myocardial deformation and HDFs was investigated in a cohort of patients with aortic stenosis (AS) and normal LVEF. Two hundred fifty three patients (median age 79 years, IQR 73 - 83 years) with mild (n = 87), moderate (n =77) and severe AS (n =89) were retrospectively enrolled. 2D echocardiographic global longitudinal strain (GLS), circumferential strain (GCS) and HDFs were determined. The worsening of AS was associated with raising inappropriate LV mass (p < 0.001) and declined LVEF, despite being in the normal range (p < 0.001). ST and HDFs parameters declined as the AS became severe (p<0.0001, for all). When patients were grouped based on the median of LV endocardial GLS value (> -19,9%) and LV systolic longitudinal force (LVsysLF) value (< 12,49), patients with impaired ST and lower HDFs components had increased incidence of aortic valve replacement (AVR) and worse survival (p <0.024 and p <0.037, respectively). Among ST and HDFs parameters, only LVsysLF was independently associated with AVR and all causes mortality on multivariable Cox regression analysis (HR 0.94; 95% CI 0.89-0.99; p= 0.012). Reduced values of LVsysLF were associated with AVR and reduced survival in AS patients. LVsysLF could provide useful information in the stratification of patients with AS and possibly in the choice of timing for AVR.

Incremental value of left ventricular global longitudinal strain in moderate aortic stenosis and reduced left ventricular ejection fraction

BACKGROUND

Moderate aortic stenosis (AS) often coexists with left ventricular (LV) systolic dysfunction and may affect survival through afterload mismatch. Because outcomes are ultimately driven by the condition of the LV, accurate assessment of LV performance is crucial to improve risk stratification. This study investigated the prognostic value of LV global longitudinal strain (GLS) in patients with moderate AS and reduced LV systolic dysfunction.

METHODS

Patients with moderate AS (aortic valve area 1.0-1.5 cm²) and reduced LV ejection fraction (EF) (<50%) were identified. LVGLS was evaluated with speckle-tracking echocardiography. Patients were divided into 2 groups according to an LVGLS value of 11%, based on spline curve analysis. The primary endpoint was all-cause mortality.

RESULTS

A total of 166 patients (mean age 73 ± 11 years, 71% male) were included. The cumulative 1- and 5-year mortality rates were higher in patients with LVGLS <11% (25% and 60%) versus LVGLS ≥11% (10% and 27%) (p < 0.001). On multivariable analysis, LVGLS as a continuous variable (HR 0.753; 95% CI 0.673-0.843; p < 0.001) and as a categorical variable (<11%) (HR 3.028; 95% CI 1.623-5.648; p < 0.001) were independently associated with outcomes, whereas LVEF was not. LVGLS provided additional prognostic information in patients with/without coronary artery disease and with mildly versus severely reduced LVEF. In addition, LVGLS had incremental prognostic value over established risk factors, including LVEF.

CONCLUSION

The combination of moderate AS and reduced LV systolic dysfunction is associated with a high mortality risk. LVGLS, but not LVEF, is independently associated with mortality and provides incremental prognostic value over established risk factors in patients with moderate AS and reduced LVEF.

Managing Patients With Moderate Aortic Stenosis

Current guidelines recommend that clinical surveillance for patients with moderate aortic stenosis (AS) and aortic valve replacement (AVR) may be considered if there is an indication for coronary revascularization. Recent observational studies, however, have shown that moderate AS is associated with an increased risk of cardiovascular events and mortality. Whether the increased risk of adverse events is caused by associated comorbidities, or to the underlying moderate AS itself, is incompletely understood. Similarly, which patients with moderate AS need close follow-up or could potentially benefit from early AVR is also unknown. In this review, the authors provide a comprehensive overview of the current literature on moderate AS. They first provide an algorithm that helps to diagnose moderate AS correctly, especially when discordant grading is observed. Although the traditional focus of AS assessment has been on the valve, it is increasingly acknowledged that AS is not only a disease of the aortic valve but also of the ventricle. The authors therefore discuss how multimodality imaging can help to evaluate the left ventricular remodeling response and improve risk stratification in patients with moderate AS. Finally, they summarize current evidence on the management of moderate AS and highlight ongoing trials on AVR in moderate AS.