The impact of global left ventricular afterload on left ventricular reverse remodeling after aortic valve replacement

Mechanisms of myocardial reverse remodelling and its clinical significance: A scientific statement of the ESC Working Group on Myocardial Function

Cardiovascular disease (CVD) is the leading cause of morbimortality in Europe and worldwide. CVD imposes a heterogeneous spectrum of cardiac remodelling, depending on the insult nature, that is, pressure or volume overload, ischaemia, arrhythmias, infection, pathogenic gene variant, or cardiotoxicity. Moreover, the progression of CVD-induced remodelling is influenced by sex, age, genetic background and comorbidities, impacting patients' outcomes and prognosis. Cardiac reverse remodelling (RR) is defined as any normative improvement in cardiac geometry and function, driven by therapeutic interventions and rarely occurring spontaneously. While RR is the outcome desired for most CVD treatments, they often only slow/halt its progression or modify risk factors, calling for novel and more timely RR approaches. Interventions triggering RR depend on the myocardial insult and include drugs (renin-angiotensin-aldosterone system inhibitors, beta-blockers, diuretics and sodium-glucose cotransporter 2 inhibitors), devices (cardiac resynchronization therapy, ventricular assist devices), surgeries (valve replacement, coronary artery bypass graft), or physiological responses (deconditioning, postpartum). Subsequently, cardiac RR is inferred from the degree of normalization of left ventricular mass, ejection fraction and end-diastolic/end-systolic volumes, whose extent often correlates with patients' prognosis. However, strategies aimed at achieving sustained cardiac improvement, predictive models assessing the extent of RR, or even clinical endpoints that allow for distinguishing complete from incomplete RR or adverse remodelling objectively, remain limited and controversial. This scientific statement aims to define RR, clarify its underlying (patho)physiologic mechanisms and address (non)pharmacological options and promising strategies to promote RR, focusing on the left heart. We highlight the predictors of the extent of RR and review the prognostic significance/impact of incomplete RR/adverse remodelling. Lastly, we present an overview of RR animal models and potential future strategies under pre-clinical evaluation.

Extent of Left Ventricular Mass Regression and Impact of Global Left Ventricular Afterload on Cardiac Events and Mortality after Aortic Valve Replacement

Patient-prosthesis mismatch (PPM) causes a high transvalvular pressure gradient and residual left ventricular (LV) hypertrophy, consequently influencing long-term results. This study aimed to find the relationships between hemodynamic parameters and LV mass regression and determine the risk predictors of major adverse cardiovascular and cerebral events (MACCE) after aortic valve replacement (AVR) for aortic stenosis. Methods and Results: Preoperative and postoperative Doppler echocardiography data were evaluated for 120 patients after AVR. The patients' mean age was 67.7 years; 55% of the patients were male. Forty-four (37%) patients suffered from MACCE during a mean follow-up period of 3.6 ± 2 years. The following hemodynamic parameters at follow-up were associated with lower relative indexed LV mass (LVMI) regression: lower postoperative indexed effective orifice area, greater mean transvalvular pressure gradient (MPG), greater stroke work loss (SWL), and concentric or eccentric LV remodeling mode. The following hemodynamic parameters at follow-up were associated with a higher risk of MACCE: higher valvuloarterial impedance (Z_VA), greater SWL, greater MPG, greater relative wall thickness, greater LVMI, and hypertrophic LV remodeling mode. Lower relative LVMI regression was associated with a higher risk of MACCE (hazard ratio, 1.01: 95% confidence interval, 1.003-1.03). The corresponding cutoff of relative LVMI regression was -14%. Conclusions: Changes in hemodynamic parameters were independently associated with relative LVMI regression. Impaired reverse remodeling and persistent residual LV hypertrophy were independent risk predictors of MACCE. An LVMI regression lower than 14% indicated higher MACCE. A postoperative Z_VA greater than 3.5 mmHg/mL/m² was an independent risk predictor of cardiac events and mortality after AVR. Preventive strategies should be used at the time of the operation to avoid PPM.

Impact of valvuloarterial impedance on left ventricular reverse remodeling after aortic valve neocuspidization

Background

Aortic valve neocuspidization (AVNeo) has emerged as a promising aortic valve procedure, and is expected to have a larger effective orifice area (EOA) than commercially available bioprostheses. It is, however, unclear which indices could facilitate left ventricular (LV) reverse remodeling after AVNeo. The aim of this study is to verify the impact of global left ventricular afterload on the LV reverse remodeling following AVNeo.

Methods

Data-available consecutive 38 patients (median age, 77; interquartile range, 72.8–82.0) undergoing AVNeo for severe aortic stenosis were enrolled in this study. Preoperative and the last follow-up echocardiographic data were retrospectively analyzed including the valvuloarterial impedance (Zva), a marker of global LV afterload. Reduction in LV geometry index (LVGI) and relative wall thickness (RWT) were used as an indicator for LV reverse remodeling.

Results

The Zva reduced in 24 patients (63.2%) during the follow-up period (median, 12 months). Reduction in Zva significantly correlated to improvement of LV geometry (LVGI (r = 0.400, p = 0.013) and RWT (r = 0.627, p < 0.001)), whereas increase in EOA index did not significantly correlate to LVGI (r = 0.009, p = 0.957), or RWT (r = 0.105, p = 0.529)). The reduction in Zva was the multivariate predictor of LV reverse remodeling.

Conclusions

Low global LV afterload led to significant LV reverse remodeling even after AVNeo, which could achieve better valve performance than the conventional bioprostheses.

Arterial Hypertension in Aortic Valve Stenosis: A Critical Update

Aortic stenosis (AS) is a very common valve disease and is associated with high mortality once it becomes symptomatic. Arterial hypertension (HT) has a high prevalence among patients with AS leading to worse left ventricle remodeling and faster degeneration of the valve. HT also interferes with the assessment of the severity of AS, leading to an underestimation of the real degree of stenosis. Treatment of HT in AS has not historically been pursued due to the fear of excess reduction in afterload without a possibility of increasing stroke volume due to the fixed aortic valve, but most recent evidence shows that several drugs are safe and effective in reducing BP in patients with HT and AS. RAAS inhibitors and beta-blockers provide benefit in selected populations based on their profile of pharmacokinetics and pharmacodynamics. Different drugs, on the other hand, have proved to be unsafe, such as calcium channel blockers, or simply not easy enough to handle to be recommended in clinical practice, such as PDE5i, MRA or sodium nitroprusside. The present review highlights all available studies on HT and AS to guide antihypertensive treatment.

Arterial biomarkers in the evaluation, management and prognosis of aortic stenosis

Degenerative aortic valve stenosis is the most common primary valve disease and a significant cause of cardiovascular morbidity and mortality. In an era when new techniques for the management of aortic stenosis are gaining ground, the understanding of this disease is more important than ever to optimize treatment. So far, the focus has been placed on the assessment of the valve itself. However, the role that the arterial system plays in the pathogenesis and natural history of the disease needs to be further elucidated. Arteriosclerosis, when it coexists with a stenotic valve, augments the load posed on the left ventricle contributing to greater impairment of cardiovascular function. Arterial stiffness, a well-established predictor for cardiovascular disease and all-cause mortality, could play a role in the prognosis and quality of life of this population. Several studies using a variety of indices to assess arterial stiffness have tried to address the potential utility of arterial function assessment in the case of aortic stenosis. Importantly, reliable data identify a prognostic role of arterial biomarkers in aortic stenosis and stress their possible use to optimize timing and method of treatment. This review aims at summarizing the existing knowledge on the interplay between the heart and the vessels in the presence of degenerative aortic stenosis, prior, upon and after interventional management. Further, it discusses the evidence supporting the potential clinical application of arterial biomarkers for the assessment of progression, severity, management and prognosis of aortic stenosis.

Preprocedural valvuloarterial impedance as a predictor of left ventricular ejection fraction improvement after transcatheter aortic valve replacement in patients with reduced left ventricular ejection fraction

BACKGROUND

Predictors of left ventricular ejection fraction (LVEF) improvement after transcatheter aortic valve replacement (TAVR) in patients with a preoperative reduced LVEF are limited.

OBJECTIVES

This study aimed to investigate the relationship between preprocedural valuvuloarterial impedance (ZVa), which represents the global LV afterload, and LVEF improvement after TAVR.

METHODS

This was a single-center, retrospective study, which included patients with symptomatic aortic valve stenosis (AS) with a reduced baseline LVEF (< 50%) underwent TAVR. Based on the difference in the LVEF before and 1 month after the procedure, they were divided into two groups: improved group (≥ 10% improvement) and non-improved group (< 10% improvement or worsening). Preprocedural ZVa and clinical outcomes were then compared. ZVa was calculated using preprocedural transthoracic echocardiography data.

RESULTS

Among 473 cases of TAVR performed from May 2012 to July 2017 at Queen's Medical Center (Honolulu, HI, USA), 99 patients (improved group, n = 42; mean age 82.0 ± 8.6 years vs. non-improved group, n = 57, mean age 81.4 ± 9.5 years) were included. The improved group had a higher baseline ZVa {4.83 (4.15-6.89) mmHg/ml/m² vs. 4.04 (3.56-4.63) mmHg/ml/m², respectively, p = 0.0009} and prevalence of ZVa > 5 mmHg/ml/m² (45.2% vs. 17.5%, respectively, p = 0.0028). Multivariable analysis of predictors of LVEF improvement ≥ 10% at 1 month identified ZVa > 5 mmHg/ml/m² [odds ratio (OR): 3.31, 95% confidence interval (CI): 1.05-11.8] as a predictor. The improved group had a lower readmission rate due to heart failure than the non-improved group (log-rank test, p = 0.043).

CONCLUSION

In conclusion, Zva is a simple, noninvasive marker that shows promise as a predictor of LVEF improvement after TAVR in reduced LVEF patients.

Imaging, Biomarker, and Clinical Predictors of Cardiac Remodeling in Heart Failure With Reduced Ejection Fraction

In response to injury, hemodynamic changes, or neurohormonal activation, the heart undergoes a series of structural and functional changes that have been termed cardiac remodeling. Remodeling is defined as changes in cardiac geometry and/or function over time and can be measured in terms of changes in cardiac chamber dimensions, wall thickness, volumes, mass, and ejection fraction at serial imaging examinations. As to cardiac chambers, left ventricular (LV) remodeling has been best studied in patients with heart failure with reduced ejection fraction. Although LV remodeling may compensate for abnormal hemodynamic parameters and function in the short term, left unchecked, it is associated with worsening cardiac function and poor prognosis. On the other hand, reversing LV geometry and/or function closer to that of a normal heart (also known as reverse remodeling) is associated with improved cardiac function and better prognosis. Because of its close relationship with clinical outcomes, remodeling may potentially be targeted in clinical management and used in trials as a surrogate endpoint. Standardized definition of remodeling and reliable tools to predict and monitor the presence, direction, and magnitude of cardiac remodeling are needed. Together with clinical and imaging findings, circulating biomarkers (most notably N-terminal pro-B-type natriuretic peptide, high-sensitivity troponin, and soluble suppression of tumorigenesis-2) may be helpful in this respect.

Changes in dynamic left ventricular function, assessed by the strain-volume loop, relate to reverse remodeling after aortic valve replacement

Aortic valve replacement (AVR) leads to remodeling of the left ventricle (LV). Adopting a novel technique to examine dynamic LV function, our study explored whether post-AVR changes in dynamic LV function and/or changes in aortic valve characteristics are associated with LV mass regression during follow-up. We retrospectively analyzed 30 participants with severe aortic stenosis who underwent standard transthoracic echocardiographic assessment before AVR [88 (IQR or interquartile range: 22–143) days], post-AVR [13 (6–22) days], and during follow-up [455 (226–907) days]. We assessed standard measures of LV structure, function, and aortic valve characteristics. Novel insight into dynamic LV function was provided through a four-chamber image by examination of the temporal relation between LV longitudinal strain (ε) and volume (ε-volume loops), representing the contribution of LV mechanics to volume change. AVR resulted in immediate changes in structural valve characteristics, alongside a reduced LV longitudinal peak ε and improved coherence between the diastolic and systolic part of the ε-volume loop (all P < 0.05). Follow-up revealed a decrease in LV mass ( P < 0.05) and improvements in LV ejection fraction and LV longitudinal peak ε ( P < 0.05). A significant relationship was present between decline in LV mass during follow-up and post-AVR improvement in coherence of the ε-volume loops ( r = 0.439, P = 0.03), but not with post-AVR changes in aortic valve characteristics or LV function (all P > 0.05). We found that post-AVR improvements in dynamic LV function are related to long-term remodeling of the LV. This highlights the potential importance of assessing dynamic LV function for cardiac adaptations in vivo.

NEW & NOTEWORTHY Combining temporal measures of left ventricular longitudinal strain and volume (strain-volume loop) provides novel insights in dynamic cardiac function. In patients with aortic stenosis who underwent aortic valve replacement, postsurgical changes in the strain-volume loop are associated with regression of left ventricular mass during follow-up. This provides novel insight into the relation between postsurgery changes in cardiac hemodynamics and long-term structural remodeling, but also supports the potential utility of the assessment of dynamic cardiac function.

Hemodynamics and reverse remodeling associated with Mosaic, Perimount and Trifecta aortic bioprostheses

Introduction: The implantation rate of aortic bioprostheses is increasing. Their durability has improved to some extent over the years and they allow for future transcatheter valve-in-valve deployment. In the lack of long term follow up, their hemodynamic profile, i.e. transvalvular mean pressure gradient and effective orifice area indexed, and the associated left ventricular reverse remodeling indexed are useful surrogates for clinical outcomes. Areas covered: A systematic review of the literature was conducted by searching Medline, Cochrane, Scielo, Embase databases, and grey literature until July 2018 for articles that perform comparisons among the three most popular aortic bioprostheses. Six randomized and 12 non-randomized studies were included with 565 patients receiving a Mosaic, 1334 a Perimount and 557 a Trifecta valve. These articles are heterogeneous but they allow the meta-analytic comparison of the abovementioned outcomes. Expert opinion: Compared to the Perimount valve, the Mosaic is hemodynamically inferior, while the Trifecta is superior. Despite these statistically significant differences, the left ventricular mass regression indexed, that is indicative of reverse remodeling, was comparable in all groups. All patients were similarly benefited. The predilection among these valves is fueled by their hemodynamic profile but not supported by the comparable reverse remodeling.

Impact of Metabolic Syndrome and/or Diabetes Mellitus on Left Ventricular Mass and Remodeling in Patients With Aortic Stenosis Before and After Aortic Valve Replacement

In aortic stenosis (AS), metabolic syndrome (MetS), and diabetes mellitus (DM) are associated with more pronounced left ventricular (LV) hypertrophy and more concentric remodeling. We aimed to assess the impact of MetS and DM on LV mass, remodeling, and LV mass regression after aortic valve replacement (AVR) in patients with severe AS. We included 177 patients with severe AS and preserved LV ejection fraction (>50%). All patients underwent a complete echocardiogram before and 1 year after AVR. Forty-seven (27%) patients had MetS, 37 (21%) DM, and 93 (52%) neither MetS nor DM (No MetS-DM). Before AVR, indexed LV mass was higher in MetS and DM groups compared with No MetS-DM group (56.1 ± 14.2, 56.2 ± 18.2 vs 49.2 ± 14.1 g/m^2.7, respectively; p <0.01). Prevalence of LV hypertrophy was higher in MetS and DM than in No MetS-DM patients (66%, 65% vs 44%, p <0.01) as well as LV mass to end-diastolic volume ratio (2.10 ± 0.44 and 2.21 ± 0.63 vs 1.96 ± 0.41 g/ml, respectively, p = 0.03). After multivariate analysis, DM and MetS were independently associated with higher baseline LV mass (p <0.05). One year after AVR, decrease in LV mass was significant (p <0.001) in all 3 groups. MetS was independently associated with less LV mass regression and higher LV mass 1 year after AVR. Therefore, MetS and DM patients showed more residual LV hypertrophy than those with No MetS-DM (57%, 38%, and 17%, p <0.01). In conclusion, MetS and DM were associated with higher preoperative LV mass, more LV hypertrophy, and more concentric remodeling. One year after AVR, MetS showed less significant LV mass regression and both DM and MetS persisted with more residual LV hypertrophy.

Hypertension and transcatheter aortic valve replacement: parallel or series?

Aortic stenosis (AS) is the most common valvular heart disease in the elderly and it causes significant morbidity and mortality. Hypertension is also highly prevalent in elderly patients with AS, and AS patients with hypertension have worse outcomes. Accurate assessment of AS severity and understanding its relationship with arterial compliance has become increasingly important as the options for valve management, particularly transcatheter interventions, have grown. The parameters used for quantifying stenosis severity have traditionally mainly focused on the valve itself. However, AS is now recognized as a systemic disease involving aging ventricles and stiff arteries rather than one limited solely to the valve. Over the last decade, valvuloarterial impedance, a measure of global ventricular load, has contributed to our understanding of the pathophysiology and course of AS in heterogeneous patients, even when segregated by symptoms and severity. This review summarizes our growing understanding of the interplay between ventricle, valve, and vessel, with a particular emphasis on downstream vascular changes after transcatheter aortic valve replacement and the role of valvuloarterial impedance in predicting left ventricular changes and prognosis in patients with various transvalvular flow patterns.