Potential role of fibrosis imaging in severe valvular heart disease

Insights into the Role of Glutathione Peroxidase 3 in Non-Neoplastic Diseases

Reactive oxygen species (ROSs) are byproducts of normal cellular metabolism and play pivotal roles in various physiological processes. Disruptions in the balance between ROS levels and the body's antioxidant defenses can lead to the development of numerous diseases. Glutathione peroxidase 3 (GPX3), a key component of the body's antioxidant system, is an oxidoreductase enzyme. GPX3 mitigates oxidative damage by catalyzing the conversion of hydrogen peroxide into water. Beyond its antioxidant function, GPX3 is vital in regulating metabolism, modulating cell growth, inducing apoptosis and facilitating signal transduction. It also serves as a significant tumor suppressor in various cancers. Recent studies have revealed aberrant expression of GPX3 in several non-neoplastic diseases, associating it with multiple pathological processes. This review synthesizes the current understanding of GPX3 expression and regulation, highlighting its extensive roles in noncancerous diseases. Additionally, this paper evaluates the potential of GPX3 as a diagnostic biomarker and explores emerging therapeutic strategies targeting this enzyme, offering potential avenues for future clinical treatment of non-neoplastic conditions.

Moving from left ventricular ejection fraction to deformation imaging in mitral valve regurgitation

The increasing prevalence of valvular heart diseases, specifically mitral regurgitation (MR), underscores the need for a careful and timely approach to intervention. Severe MR, whether primary or secondary, when left untreated leads to adverse outcomes, emphasizing the critical role of a timely surgical or transcatheter intervention. While left ventricular ejection fraction (LVEF) remains the guideline-recommended measure for assessing left ventricle damage, emerging evidence raises concerns regarding its reliability in MR due to its volume-dependent nature. This review summarizes the existing literature on the role of LVEF and deformation imaging techniques, emphasizing the latter's potential in providing a more accurate evaluation of intrinsic myocardial function. Moreover, it advocates the need for an integrated approach that combines traditional with emerging measures, aiming to optimize the management of patients with MR. It attempts to highlight the need for future research to validate the clinical application of deformation imaging techniques through large-scale studies.

Gpx3 and Egr1 Are Involved in Regulating the Differentiation Fate of Cardiac Fibroblasts under Pressure Overload

Objectives

Although myocardial fibrosis is a common pathophysiological process associated with many heart diseases, the molecular mechanisms regulating the development of fibrosis have not been fully determined. Recently, single cell RNA sequencing (scRNA-seq) analysis has been used to examine cellular fate and function during cellular differentiation and has contributed to elucidating the mechanisms of various diseases. The main purpose of this study was to characterize the fate of cardiac fibroblasts (CFs) and the dynamic gene expression patterns in a model of cardiac pressure overload using scRNA-seq analysis.

Methods

The public scRNA-seq dataset of the transverse aortic coarctation (TAC) model in mice was downloaded from the GEO database, GSE155882. First, we performed quality control, dimensionality reduction, clustering, and annotation of the data through the Seurat R package (v4.0.5). Then, we constructed the pseudotime trajectory of cell development and identified key regulatory genes using the Monocle R package (v2.22.0). Different cell fates and groups were fully characterized by Gene Set Enrichment Analysis (GSEA) analysis and Transcription factor (TF) activity analysis. Finally, we used Cytoscape (3.9.1) to extensively examine the gene regulatory network related to cell fate.

Results

Pseudotime analysis showed that CFs differentiated into two distinct cell fates, one of which produced activated myofibroblasts, and the other which produced protective cells that were associated with reduced fibrosis levels, increased antioxidative stress responses, and the ability to promote angiogenesis. In the TAC model, activated CFs were significantly upregulated, while protective cells were downregulated. Treatment with the bromodomain inhibitor JQ1 reversed this change and improved fibrosis. Analysis of dynamic gene expression revealed that Gpx3 was significantly upregulated during cell differentiation into protective cells. Gpx3 expression was affected by JQ1 treatment. Furthermore, Gpx3 expression levels were negatively correlated with the different levels of fibrosis observed in the various treatment groups. Finally, we found that transcription factors Jun, Fos, Atf3, and Egr1 were upregulated in protective cells, especially Egr1 was predicted to be involved in the regulation of genes related to antioxidant stress and angiogenesis, suggesting a role in promoting differentiation into this cell phenotype.

Conclusions

The scRNA-seq analysis was used to characterize the dynamic changes associated with fibroblast differentiation and identified Gpx3 as a factor that might be involved in the regulation of myocardial fibrosis under cardiac pressure overload. These findings will help to further understanding of the mechanism of fibrosis and provide potential intervention targets.

Remodeling classification system considering left ventricular volume in patients with aortic valve stenosis: Association with adverse cardiovascular outcomes

BACKGROUND

To assess prevalence and clinical implications of left ventricular (LV) remodeling considering: LV volume, mass and relative wall thickness at the time of aortic valve stenosis diagnosis.

METHODS AND RESULTS

We retrospectively analyzed 343 patients (age 79.2 ± 9.5 years, 48.1% males) with functional aortic valve area (AVA) ≤ 1.5 cm² . LV geometric patterns and clinical outcomes (combined death, cardiac hospitalization, aortic valve replacement [AVR]) were evaluated. According to the new LV remodeling classification, 4.9% had normal geometry, 7.5% concentric remodeling, 39.3% concentric hypertrophy (LVH), 22.4% mixed LVH, 12.5% dilated LVH, 3.2% eccentric LVH and 4.3% eccentric remodeling, 5.5% had not classifiable LVH. Indexed stroke volume (SVi) was higher in patients with concentric LVH (40.3 ± 11.9 mL/m² ) and mixed LVH (41.6 ± 13.4 mL/m² ) and lower in patients with eccentric LVH (24.9 ± 7.7 mL/m² ), concentric (36.6 ± 12.7 mL/m² ) and eccentric remodeling (34.9 ± 9.5 mL/m² ), P = 0.003. During a median follow-up of 2.2 years, 260 (75.8%) had the combined end point. A significant association between the combined end point and LV dilation (P = 0.010) or LV remodeling patterns (P = 0.0001) was found. After multivariable adjustment for AVR, concentric remodeling (HR 3.12, IC 95% 1.14-8.55; P = 0.02) and dilated LVH (HR 3.48, IC 95% 1.31-9.27; P = 0.01) were strongly associated with death or cardiac hospitalizations.

CONCLUSIONS

In patients with AVA ≤ 1.5 cm² , when the new LV remodeling classification system is applied, only a minority had normal geometry and less than half had "classic" concentric LVH or remodeling. LV volume dilatation is frequent and associated with adverse outcome. Concentric remodeling, eccentric remodeling, dilated LVH had the worst noninvasive hemodynamic profile and prognosis.

Impact of left ventricular remodelling patterns on outcomes in patients with aortic stenosis

Aims

The objective of this study was to examine the association between the different patterns of left ventricular (LV) remodelling/hypertrophy on all-cause and cardiovascular mortality in patients with aortic stenosis (AS).

Methods and results

In total, 747 consecutive patients (69 ± 14 years, 57% men) with AS and preserved LV ejection fraction were included in this study. According to LV mass index and relative wall thickness, patients were classified into four LV patterns: normal, concentric remodelling (CR), concentric hypertrophy (CH), and eccentric hypertrophy (EH). One hundred and sixteen patients (15%) had normal pattern, 66 (9%) had EH, 169 (23%) had CR, and 396 (53%) had CH. During a median follow-up of 6.4 years, 339 patients died (242 from cardiovascular causes). CH was associated with higher risk of all-cause mortality compared with the three other LV patterns (all P < 0.05). After multivariable adjustment, CH remained associated with higher risk of mortality (HR = 1.27, 95% CI 1.01-1.61, P = 0.046). There was a significant interaction (P < 0.05) between sex and CH with regards to the impact on mortality: CH was associated with worse outcome in women (P = 0.0001) but not in men (P = 0.22). In multivariable analysis, CH remained associated with higher risk of worse outcome in women (HR = 1.56, 95% CI 1.08-2.24, P = 0.018).

Conclusions

This study shows that CH was independently associated with increased risk of mortality in AS patients with preserved ejection fraction. This association was observed in women but not in men. The pattern of LV remodelling/hypertrophy should be integrated in the risk stratification process in patients with AS.

Forward Left Ventricular Ejection Fraction: A Simple Risk Marker in Patients With Primary Mitral Regurgitation

Background

The timing of mitral valve surgery in asymptomatic patients with primary mitral regurgitation (MR) is controversial. We hypothesized that the forward left ventricular (LV) ejection fraction (LVEF; ie, LV outflow tract stroke volume divided by LV end‐diastolic volume) is superior to the total LVEF to predict outcomes in MR. The objective of this study was to examine the association between echocardiographic parameters of MR severity and LV function and outcomes in patients with MR.

Methods and Results

The clinical and Doppler‐echocardiographic data of 278 patients with ≥mild MR and no class I indication of mitral valve surgery at baseline were retrospectively analyzed. The primary study end point was the composite of mitral valve surgery or death. During a mean follow‐up of 5.4±3.2 years, there were 147 (53%) events: 96 (35%) MV surgeries and 66 (24%) deaths. Total LVEF and global longitudinal strain were not associated with the occurrence of events, whereas forward LVEF (P<0.0001) and LV end‐systolic diameter (P=0.0003) were. After adjustment for age, sex, MR severity, Charlson probability, coronary artery disease, and atrial fibrillation, forward LVEF remained independently associated with the occurrence of events (adjusted hazard ratio: 1.09, [95% confidence interval]: 1.02–1.17 per 5% decrease; P=0.01), whereas LV end‐systolic diameter was not (P=0.48).

Conclusions

The results of this study suggest that the forward LVEF may be superior to the total LVEF and LV end‐systolic diameter to predict outcomes in patients with primary MR. This simple and easily measurable parameter may be useful to improve risk stratification and select the best timing for intervention in patients with primary MR.

A primer on current progress in cardiac fibrosis

Cardiac fibrosis is a significant global health problem that is closely associated with multiple forms of cardiovascular disease, including myocardial infarction, dilated cardiomyopathy, and diabetes. Fibrosis increases myocardial wall stiffness due to excessive extracellular matrix deposition, causing impaired systolic and diastolic function, and facilitating arrhythmogenesis. As a result, patient morbidity and mortality are often dramatically elevated compared with those with cardiovascular disease but without overt fibrosis, demonstrating that fibrosis itself is both a pathologic response to existing disease and a significant risk factor for exacerbation of the underlying condition. The lack of any specific treatment for cardiac fibrosis in patients suffering from cardiovascular disease is a critical gap in our ability to care for these individuals. Here we provide an overview of the development of cardiac fibrosis, and discuss new research directions that have recently emerged and that may lead to the creation of novel treatments for patients with cardiovascular diseases. Such treatments would, ideally, complement existing therapy by specifically focusing on amelioration of fibrosis.

[Wild-type transthyretin-related cardiac amyloidosis and degenerative aortic stenosis: Two inter-related pathologies in the elderly]

Wild-type transthyretin-related cardiac amyloidosis (ATTRwt) and degenerative aortic stenosis share a common demographic and clinical profile. It was recently suggested that some of the complications arising during and after transcatheter aortic valve replacement (TAVR) could be due to a co-existing cardiac amyloidosis. In a series of autopsies of patients who had undergone TAVR, researchers found ATTR amyloidosis in one third of the cases. A report is presented on two patients with aortic stenosis who were diagnosed with ATTRwt when they were about to undergo a TAVI. ATTRwt is a slowly progressing disease so we need to review the decisions on the therapeutic approach in these patients.

Left ventricular systolic function assessment in secondary mitral regurgitation: left ventricular ejection fraction vs. speckle tracking global longitudinal strain

AIMS

Left ventricular (LV) ejection fraction (LVEF) is currently considered for the decision making of patients with mitral regurgitation (MR). However, LVEF represents change in LV volume between end-diastole and end-systole but does not characterize the intrinsic function of the myocardium. In contrast, speckle-tracking global longitudinal strain (GLS) characterizes myocardial deformation. The present study evaluated whether LV GLS may detect further impairment in LV systolic function in dilated cardiomyopathy patients with and without severe secondary MR matched based on LVEF.

METHODS AND RESULTS

Patients with non-ischaemic dilated cardiomyopathy (N = 150, 59 ± 12 years old, 58% male) were included: 75 patients with severe secondary MR and 75 patients with none or less than mild MR matched 1 : 1 according to LVEF. The LV systolic function was evaluated by LVEF (following Simpson's biplane method), forward ejection fraction (forward stroke volume relative to LV end-diastolic volume), and speckle-tracking GLS. By definition, LVEF was comparable between the two groups (patients with severe MR 31 ± 10 vs. patients with no/mild MR 31 ± 10%, P = 0.93). However, patients with severe MR had significantly lower forward ejection fraction (29 ± 14 vs. 40 ± 18%, P < 0.001) and more impaired GLS (-8.08 ± 3.33 vs. -9.78 ± 3.78%, P = 0.004) compared with their counterparts. The presence of severe secondary MR was significantly associated with worse LV GLS (β 1.32, 95% confidence interval 0.14-2.49, P = 0.03).

CONCLUSION

In patients with severe secondary MR, speckle-tracking GLS shows more deteriorated LV systolic function than LVEF.