Right ventricular function in pulmonary (arterial) hypertension

The role of the TAPSE/sPAP ratio as a predictor of mortality in Pulmonary Arterial Hypertension: Its value for patient risk stratification

Background

The tricuspid annular plane systolic excursion and systolic pulmonary artery pressure (TAPSE/sPAP) ratio has been proposed as an indicator of ventriculo-arterial coupling, predicting right ventricular failure (RVF) and mortality in patients with pulmonary arterial hypertension (PAH).

Objective

To evaluate the usefulness of the TAPSE/sPAP ratio in predicting outcomes and improving risk stratification in patients with PAH.

Methods

156 patients with PAH were included. Clinical, functional, echocardiographic, and haemodynamic variables, along with the TAPSE/sPAP ratio, were analysed based on etiological PAH subgroups and outcomes. Additional statistical measures, such as the area under the curve (AUC), net reclassification index (NRI), and integrated discrimination improvement, assessed the predictive ability of TAPSE/sPAP in combination with the ESC/ERS risk score, and other risk assessment strategies (COMPERA and Reveal Lite 2).

Results

Most patients were female (86.5%), with a median age of 45.5 (IQR: 29-58) years. The TAPSE/sPAP ratio for the whole group was 0.26 (IQR: 0.190-0.347) mm/mmHg, which was similar among different aetiologies, but different between deceased and surviving patients (0.14 vs. 0.27 mm/mmHg, respectively, P < 0.001). A TAPSE/sPAP ratio <0.18 mm/mmHg independently predicted mortality (AUC: 0.859, 95% CI: 0.766- 0.952; P < 0.001). Integration with the ESC/ERS risk score improved predicted mortality (AUC: 0.87 vs. 0.75, p = 0.002) and risk stratification, reclassifying 14.28% of events and 36.92% of non-events, with an NRI of 39.4% (P < 0.001). Likewise, integration with other scores improved predicted ability of COMPERA and REVEA Lite2; COMPERA+TAPSE/sPAP (AUC: 0.837 vs 0.742; p = 0.005) and REVEAL Lite 2 +TAPSE/sPAP (AUC: 0.840 vs. 0.713; p < 0.001).

Conclusions

A TAPSE/sPAP ratio <0.18 mm/mmHg predicts mortality in PAH. The combination of the TAPSE/sPAP ratio with the ESC/ERS risk score improved risk stratification, and reclassification emphasizing the potential of ESC/ERS+TAPSE/sPAP as a valuable tool for risk assessment and clinical decision-making in PAH patients. Integration of TAPSE/sPAP ratio with other scores (COMPERA and (REVEAL Lite 2) also improved the risk stratification and reclassification of these risk scores.

Tricuspid annular plane systolic excursion to pulmonary artery systolic pressure ratio in chronic thromboembolic pulmonary hypertension improves with balloon pulmonary angioplasty

Right ventricle (RV)-to-pulmonary artery (PA) coupling measured by the ratio of echocardiography-derived tricuspid annular plane systolic excursion (TAPSE) and pulmonary artery systolic pressure (PASP) is a meaningful prognostic marker in pulmonary hypertension (PH). It's unclear if balloon pulmonary angioplasty (BPA) treatment of chronic thromboembolic pulmonary hypertension (CTEPH) alters RV-PA coupling measured by TAPSE/PASP. We reviewed CTEPH patients treated with BPA at our institution who had a transthoracic echocardiogram (TTE) before BPA and a follow-up TTE at any point during BPA. TAPSE was obtained from the initial and lattermost TTE; hemodynamics were obtained before each BPA session. Between March 2015 to October 2023, there were 228 patients treated with BPA. After excluding post-PTE patients and those without PH, 67 were included. Initial TAPSE/PASP was 0.39 ± 0.21 mm/mmHg. Using previously defined TAPSE/PASP tertiles in PH (<0.19, 0.19-0.32, >0.32 mm/mmHg), there were 6 patients (9%) in low, 30 (45%) in middle, and 31 (46%) in the high tertiles at baseline. The lower TAPSE/PASP tertiles had more severe baseline hemodynamics (p < 0.001) compared to the high TAPSE/PASP cohort. At follow-up, TAPSE/PASP improved to 0.47 ± 0.20 mm/mmHg (p = 0.023), with 2 (3%), 13 (19%), and 52 (78%) patients in the low, middle, high TAPSE/PASP tertiles, respectively. As patients progress through BPA sessions, the TAPSE/PASP ratio increases, possibly reflecting improved RV mechanics and RV-PA coupling. TAPSE/PASP ratio as a marker of RV-PA coupling can improve with BPA treatment and may be an important measure to follow during treatment of CTEPH.

Non-invasive imaging techniques for early diagnosis of bilateral cardiac dysfunction in pulmonary hypertension: current crests, future peaks

Pulmonary arterial hypertension (PAH) is a chronic and progressive disease that eventually leads to heart failure (HF) and subsequent fatality if left untreated. Right ventricular (RV) function has proven prognostic values in patients with a variety of heart diseases including PAH. PAH is predominantly a right heart disease; however, given the nature of the continuous circulatory system and the presence of shared septum and pericardial constraints, the interdependence of the right and left ventricles is a factor that requires consideration. Accurate and timely assessment of ventricular function is very important in the management of patients with PAH for disease outcomes and prognosis. Non-invasive modalities such as cardiac magnetic resonance (CMR) and echocardiography (two-dimensional and three-dimensional), and nuclear medicine, positron emission tomography (PET) play a crucial role in the assessment of ventricular function and disease prognosis. Each modality has its own strengths and limitations, hence this review article sheds light on (i) ventricular dysfunction in patients with PAH and RV-LV interdependence in such patients, (ii) the strengths and limitations of all available modalities and parameters for the early assessment of ventricular function, as well as their prognostic value, and (iii) lastly, the challenges faced and the potential future advancement in these modalities for accurate and early diagnosis of ventricular function in PAH.

Transcriptional profiling unveils molecular subgroups of adaptive and maladaptive right ventricular remodeling in pulmonary hypertension

Right ventricular (RV) function is critical to prognosis in all forms of pulmonary hypertension. Here we perform molecular phenotyping of RV remodeling by transcriptome analysis of RV tissue obtained from 40 individuals, and two animal models of RV dysfunction of both sexes. Our unsupervised clustering analysis identified 'early' and 'late' subgroups within compensated and decompensated states, characterized by the expression of distinct signaling pathways, while fatty acid metabolism and estrogen response appeared to underlie sex-specific differences in RV adaptation. The circulating levels of several extracellular matrix proteins deregulated in decompensated RV subgroups were assessed in two independent cohorts of individuals with pulmonary arterial hypertension, revealing that NID1, C1QTNF1 and CRTAC1 predicted the development of a maladaptive RV state, as defined by magnetic resonance imaging parameters, and were associated with worse clinical outcomes. Our study provides a resource for subphenotyping RV states, identifying state-specific biomarkers, and potential therapeutic targets for RV dysfunction.

Evaluation of right-ventricular function by two-dimensional echocardiography and two-dimensional speckle-tracking echocardiography in patients with successful RCA CTO recanalization

OBJECTIVES

Chronic total occlusion (CTO) of the right coronary artery (RCA) is common in patients with coronary artery disease. Although revascularization techniques and success rates have improved significantly in recent years, there are still no studies investigating possible effects of successful recanalization of RCA CTO on the right-ventricular (RV) function. With this study, we aimed to evaluate RV function after recanalization of the RCA by two-dimensional transthoracic echocardiography (2DE) and additional two-dimensional speckle-tracking echocardiography (2DSTE).

METHODS AND RESULTS

Our analysis included 102 patients undergoing successful RCA CTO recanalization at the University Medical Center of Mainz. All patients underwent 2DE and 2DSTE to assess RV function before PCI procedure and 6 months after successful revascularization. We found an altered RV function in our collective at baseline assessed by 2DSTE with a significant improvement at 6 month follow-up (baseline RV free wall strain: - 20.7 [- 6.3 to - 32.0] % vs. - 23.4 [- 8.3 to - 39.3] % at follow-up, p < 0.001 and baseline RV global strain - 15.9 [- 6.0 to - 25.7] % vs. - 17.9 [- 7.0 to - 29.5] % at follow-up, p < 0.001).

CONCLUSION

RV function was altered in patients with RCA CTO and showed significant improvement after successful recanalization. We also noticed an improvement in patient-reported clinical symptoms. Our study suggests that CTO procedure is a beneficial treatment option in symptomatic patients with RCA CTO.

Right ventricular failure in pulmonary hypertension: recent insights from experimental models

Right ventricular (RV) function is a critical determinant of the prognosis of patients with pulmonary hypertension (PH). Upon establishment of PH, RV dysfunction develops, leading to a gradual worsening of the condition over time, culminating in RV failure and premature mortality. Despite this understanding, the underlying mechanisms of RV failure remain obscure. As a result, there are currently no approved therapies specifically targeting the right ventricle. One contributing factor to the lack of RV-directed therapies is the complexity of the pathogenesis of RV failure as observed in animal models and clinical studies. In recent years, various research groups have begun utilizing multiple models, including both afterload-dependent and afterload-independent models, to investigate specific targets and pharmacological agents in RV failure. In this review, we examine various animal models of RV failure and the recent advancements made utilizing these models to study the mechanisms of RV failure and the potential efficacy of therapeutic interventions, with the ultimate goal of translating these findings into clinical practice to enhance the management of individuals with PH.

Adaptive versus maladaptive right ventricular remodelling

Right ventricular (RV) function and its adaptation to increased afterload [RV-pulmonary arterial (PA) coupling] are crucial in various types of pulmonary hypertension, determining symptomatology and outcome. In the course of disease progression and increasing afterload, the right ventricle undergoes adaptive remodelling to maintain right-sided cardiac output by increasing contractility. Exhaustion of compensatory RV remodelling (RV-PA uncoupling) finally leads to maladaptation and increase of cardiac volumes, resulting in heart failure. The gold-standard measurement of RV-PA coupling is the ratio of contractility [end-systolic elastance (Ees)] to afterload [arterial elastance (Ea)] derived from RV pressure-volume loops obtained by conductance catheterization. The optimal Ees/Ea ratio is between 1.5 and 2.0. RV-PA coupling in pulmonary hypertension has considerable reserve; the Ees/Ea threshold at which uncoupling occurs is estimated to be ~0.7. As RV conductance catheterization is invasive, complex, and not widely available, multiple non-invasive echocardiographic surrogates for Ees/Ea have been investigated. One of the first described and best validated surrogates is the ratio of tricuspid annular plane systolic excursion to estimated pulmonary arterial systolic pressure (TAPSE/PASP), which has shown prognostic relevance in left-sided heart failure and precapillary pulmonary hypertension. Other RV-PA coupling surrogates have been formed by replacing TAPSE with different echocardiographic measures of RV contractility, such as peak systolic tissue velocity of the lateral tricuspid annulus (S'), RV fractional area change, speckle tracking-based RV free wall longitudinal strain and global longitudinal strain, and three-dimensional RV ejection fraction. PASP-independent surrogates have also been studied, including the ratios S'/RV end-systolic area index, RV area change/RV end-systolic area, and stroke volume/end-systolic volume. Limitations of these non-invasive surrogates include the influence of severe tricuspid regurgitation (which can cause distortion of longitudinal measurements and underestimation of PASP) and the angle dependence of TAPSE and PASP. Detection of early RV remodelling may require isolated analysis of single components of RV shortening along the radial and anteroposterior axes as well as the longitudinal axis. Multiple non-invasive methods may need to be applied depending on the level of RV dysfunction. This review explains the mechanisms of RV (mal)adaptation to its load, describes the invasive assessment of RV-PA coupling, and provides an overview of studies of non-invasive surrogate parameters, highlighting recently published works in this field. Further large-scale prospective studies including gold-standard validation are needed, as most studies to date had a retrospective, single-centre design with a small number of participants, and validation against gold-standard Ees/Ea was rarely performed.

A review of cardio-pulmonary microvascular dysfunction in pulmonary hypertension

Microvascular dysfunction progressing to pulmonary hypertension can be a primary cause of right ventricular failure or a secondary cause because of an underlying systemic illness. Little is known regarding the etiology and epidemiology of coronary microvascular dysfunction in pulmonary hypertension. Despite this limitation, its presence has been described in patients with pulmonary hypertension. This review focuses on the pathogenesis of cardiac and pulmonary microvascular dysfunction in pulmonary hypertension. Additionally, this review provides a contemporary assessment on the diagnosis and treatment of microvascular dysfunction in patients in pulmonary hypertension. This topic is important to raise awareness of microvascular dysfunction in the coronary and pulmonary circulation, so that future studies will investigate its impact on the pulmonary hypertension patient cohort.

2D speckle-tracking echocardiography as a prognostic imaging modality for COVID-19 adverse outcomes

2D speckle-tracking echocardiography (2D-STE) has been used to assess cardiac recovery during the COVID-19 patient follow-ups within the pandemic. The novel role of STE in predicting adverse outcomes of COVID-19 has received attention due to its high sensitivity in identifying subclinical myocardial dysfunction. We reviewed the studies on using 2D-STE to assess COVID-19 prognosis. A literature search was conducted on PubMed and Scopus for eligible articles, 24 of which discussed using prognostic 2D-STE for COVID-19 patients. 2D-STE predicts cardiovascular impairments more rapidly and precisely than conventional echocardiography. The 2D-STE technique presents an independent prognostic factor in COVID-19 infection. 2D-STE could be considered a time-efficient and accurate risk predictor of all-cause mortality in COVID-19 patients.

Modeling Cardiomyocyte Mechanics and Autoregulation of Contractility by Mechano-Chemo-Transduction Feedback

The heart pumps blood into circulation against vascular resistance and actively regulates the contractile force to compensate for mechanical load changes. Our experimental data show that cardiomyocytes have a mechano-chemo-transduction (MCT) mechanism that increases intracellular Ca2+ transient to enhance contractility in response to increased mechanical load. This study advances the cardiac excitation- Ca2+ signaling-contraction (E-C) coupling model on conceptual and technical fronts. First, we developed analytical and computational models to perform 3-dimensional mechanical analysis of cardiomyocytes contracting in a viscoelastic medium under mechanical load. Next, we proposed an MCT feedback loop in the E-C coupling dynamic system to shift the feedforward paradigm of cardiac E-C coupling to an autoregulation model. Our combined modeling and experimental studies reveal that MCT enables autoregulation of E-C coupling and contractility in single cardiomyocytes, which underlies the heart’s intrinsic autoregulation in compensatory response to load changes in order to maintain the stroke volume and cardiac output.

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Excitation-contraction (E-C) coupling has mechano-chemo-transduction (MCT) feedback

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MCT feedback enables autoregulation of E-C coupling when contracting under load

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Models for 3D mechanical analyses of cardiomyocytes contraction

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Shifts the paradigm of cardiac E-C coupling from feedforward to autoregulation model

Lack of right ventricular hypertrophy is associated with right heart failure in patients with left ventricular failure

Presence of right heart failure (RHF) is associated with a worse prognosis in patients with left ventricular failure (LVF). While the cause of RHF secondary to LVF is multifactorial, an increased right ventricular (RV) afterload is believed as the major cause of RHF. However, data are scarce on the adaptive responses of the RV in patients with LVF. Our aim was to understand the relationship of right ventricular hypertrophy (RVH) with RHF and RV systolic and diastolic properties in patients with LVF. 55 patients with a left ventricular ejection fraction of 40% or less were included in the present study. A comprehensive two-dimensional transthoracic echocardiographic examination was done to all participants. 12 patients (21.8%) had RHF, and patients with RHF had a significantly lower right ventricular free wall thickness (RVFWT) as compared to patients without RHF (5.3 ± 1.7 mm vs. 6.6 ± 0.9 mm, p = 0.02) and the difference remained statistically significant after adjusting for confounders (Δx̅:1.34 mm, p = 0.002). RVFWT had a statistically significant correlation with tricuspid annular plane systolic excursion (r = 0.479, p < 0.001) and tricuspid annular lateral systolic velocity (r = 0.360, p = 0.007), but not with the indices of the RV diastolic function. None of the patients with concentric RVH had RHF, while 22.2% of patients with eccentric RVH and 66.7% of patients without RVH had RHF (p < 0.01 as compared to patients with concentric RVH). In patients with left ventricular systolic dysfunction, absence of RVH was associated with worse RV systolic performance and a significantly higher incidence of RHF.

Invasive Right Ventricular Pressure-Volume Analysis: Basic Principles, Clinical Applications, and Practical Recommendations

Right ventricular pressure-volume (PV) analysis characterizes ventricular systolic and diastolic properties independent of loading conditions like volume status and afterload. While long-considered the gold-standard method for quantifying myocardial chamber performance, it was traditionally only performed in highly specialized research settings. With recent advances in catheter technology and more sophisticated approaches to analyze PV data, it is now more commonly used in a variety of clinical and research settings. Herein, we review the basic techniques for PV loop measurement, analysis, and interpretation with the aim of providing readers with a deeper understanding of the strengths and limitations of PV analysis. In the second half of the review, we detail key scenarios in which right ventricular PV analysis has influenced our understanding of clinically relevant topics and where the technique can be applied to resolve additional areas of uncertainty. All told, PV analysis has an important role in advancing our understanding of right ventricular physiology and its contribution to cardiovascular function in health and disease.

Risk assessment in pulmonary hypertension based on routinely measured laboratory parameters

BACKGROUND

γ-glutamyl transferase (GGT), the aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio, and the neutrophil-to-lymphocyte ratio (NLR) are prognostic biomarkers in several cardiovascular diseases, but their relevance in pulmonary hypertension (PH) is not fully understood. We aimed to assess their prognostic value in patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic PH (CTEPH).

METHODS

We retrospectively analyzed 731 incident patients with idiopathic PAH or CTEPH who entered the Giessen PH registry during 1993-2019. A risk stratification score based on GGT, AST/ALT ratio, and NLR tertiles was compared with a truncated version of the European Society of Cardiology/European Respiratory Society (ESC/ERS) risk stratification scheme. Associations with survival were evaluated using Kaplan-Meier and Cox regression analyses. External validation was performed in 311 patients with various types of PAH or CTEPH from a second German center.

RESULTS

GGT levels, AST/ALT, and NLR independently predicted mortality at baseline and during follow-up. The scoring system based on these biomarkers predicted mortality at baseline and during follow-up (both log-rank p < 0.001; hazard ratio [95% confidence interval], high vs low risk: baseline, 7.6 [3.9, 15.0]; follow-up, 13.3 [4.8, 37.1]). Five-year survival of low, intermediate, and high risk groups was 92%, 76%, and 51%, respectively, at baseline and 95%, 78%, and 50%, respectively, during follow-up. Our scoring system showed characteristics comparable to the ESC/ERS scheme, and predicted mortality in the validation cohort.

CONCLUSION

GGT, AST/ALT, and NLR were reliable prognostic biomarkers at baseline and during follow-up, with predictive power comparable to the gold standard for risk stratification.

Ventricular-vascular coupling is predictive of adverse clinical outcome in paediatric pulmonary arterial hypertension

Aims

Ventricular–vascular coupling, the ratio between the right ventricle’s contractile state (E_es) and its afterload (E_a), may be a useful metric in the management of paediatric pulmonary arterial hypertension (PAH). In this study we assess the prognostic capacity of the ventricular–vascular coupling ratio (E_es/E_a) derived using right ventricular (RV) pressure alone in children with PAH.

Methods

One hundred and thirty paediatric patients who were diagnosed with PAH via right heart catheterisation were retrospectively reviewed over a 10-year period. Maximum RV isovolumic pressure and end-systolic pressure were estimated using two single-beat methods from Takeuchi et al (E_es/E_a_(Takeuchi)) and from Kind et al (E_es/E_a_(Kind)) and used with an estimate of end-systolic pressure to compute ventricular–vascular coupling from pressure alone. Patients were identified as either idiopathic/hereditary PAH or associated PAH (IPAH/HPAH and APAH, respectively). Haemodynamic data, clinical functional class and clinical worsening outcomes—separated into soft (mild) and hard (severe) event categories—were assessed. Adverse soft events included functional class worsening, syncopal event, hospitalisation due to a proportional hazard-related event and haemoptysis. Hard events included death, transplantation, initiation of prostanoid therapy and hospitalisation for atrial septostomy and Pott’s shunt. Cox proportional hazard modelling was used to assess whether E_es/E_a was predictive of time-to-event.

Results

In patients with IPAH/HPAH, E_es/E_a_(Kind) and E_es/E_a_(Takeuchi) were both independently associated with time to hard event (p=0.003 and p=0.001, respectively) and when adjusted for indexed pulmonary vascular resistance (p=0.032 and p=0.013, respectively). Neither E_es/E_a_(Kind) nor E_es/E_a_(Takeuchi) were associated with time to soft event. In patients with APAH, neither E_es/E_a_(Kind) nor E_es/E_a_(Takeuchi) were associated with time to hard event or soft event.

Conclusions

E_es/E_a derived from pressure alone is a strong independent predictor of adverse outcome and could be a potential powerful prognostic tool for paediatric PAH.

The effect of moderate and severe COVID-19 pneumonia on short-term right ventricular functions: a prospective observational single pandemic center analysis

It has been reported that myocardial damage and heart failure are more common in COVID-19 patients with severe symptoms. The aim of our study was to measure the right ventricular functions of COVID-19 patients 30 days after their discharge, and compare them to the right ventricular functions of healthy volunteers. Fifty one patients with COVID-19 and 32 healthy volunteers who underwent echocardiographic examinations were enrolled in our study. 29 patients were treated for severe and 22 patients were treated for moderate COVID-19 pneumonia. The study was conducted prospectively, in a single center, between 15 May 2020 and 15 July 2020. We analyzed the right ventricular functions of the patients using conventional techniques and two-dimensional speckle-tracking. Right ventricular end-diastolic and end-systolic area were statistically higher than control group. The right ventricular fractional area change (RVFAC) was significantly lesser in the patient group compared to the control group. Tricuspid annular plane systolic motion (TAPSE) was within normal limits in both groups, it was lower in the patient group compared to the control group. Pulmonary artery pressure was found to be significantly higher in the patient group. Right ventricular global longitudinal strain (RV-GLS) was lesser than the control group (- 15.7 [(- 12.6)-(- 18.7)] vs. - 18.1 [(- 14.8)-(- 21)]; p 0.011). Right ventricular free wall strain (RV-FWS) was lesser in the patient group compared to the control group (- 16 [(- 12.7)-(- 19)] vs - 21.6 [(- 17)-(- 25.3)]; p < 0.001). We found subclinical right ventricular dysfunction in the echocardiographies of COVID-19 patients although there were no risk factors.

Evaluation of biventricular function in patients with COVID-19 using speckle tracking echocardiography

A new infectious outbreak sustained by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is now spreading all around the world. The aim of this study was to evaluate the prognostic value of left ventricular global longitudinal strain (LV-GLS) and right ventricular longitudinal strain (RV-LS) in patients with coronavirus disease 2019 (COVID-19). In this prospective, single-center study, data were gathered from patients treated for COVID-19 between April 15 and April 30, 2020. Two-dimensional echocardiography (2-DE) and speckle tracking echocardiography (STE) images were obtained for all patients. Patients were divided into three groups: those with severe COVID-19 infection, those with non-severe COVID-19 infection, and those without COVID-19 infection (the control group). Data regarding clinical characteristics and laboratory findings were obtained from electronic medical records. The primary endpoint was in-hospital mortality. A total of 100 patients hospitalized for COVID-19 were included in this study. The mean age of the severe group (n = 44) was 59.1 ± 12.9, 40% of whom were male. The mean age of the non-severe group (n = 56) was 53.7 ± 15.1, 58% of whom were male. Of these patients, 22 died in the hospital. In patients in the severe group, LV-GLS and RV-LS were decreased compared to patients in the non-severe and control groups (LV-GLS: - 14.5 ± 1.8 vs. - 16.7 ± 1.3 vs. - 19.4 ± 1.6, respectively [p < 0.001]; RV-LS: - 17.2 ± 2.3 vs. - 20.5 ± 3.2 vs. - 27.3 ± 3.1, respectively [p < 0.001]). The presence of cardiac injury, D-dimer, arterial oxygen saturation (SaO2), LV-GLS (OR 1.63, 95% confidence interval [CI] 1.08-2.47; p = 0.010) and RV-LS (OR 1.55, 95% CI 1.07-2.25; p = 0.019) were identified as independent predictors of mortality via multivariate analysis. LV-GLS and RV-LS are independent predictors of in-hospital mortality in patients with COVID-19.

Epigenetic Regulation of Pulmonary Arterial Hypertension-Induced Vascular and Right Ventricular Remodeling: New Opportunities?

Pulmonary artery hypertension (PAH) is a rare chronic disease with high impact on patients’ quality of life and currently no available cure. PAH is characterized by constant remodeling of the pulmonary artery by increased proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs), fibroblasts (FBs) and endothelial cells (ECs). This remodeling eventually leads to increased pressure in the right ventricle (RV) and subsequent right ventricle hypertrophy (RVH) which, when left untreated, progresses into right ventricle failure (RVF). PAH can not only originate from heritable mutations, but also develop as a consequence of congenital heart disease, exposure to drugs or toxins, HIV, connective tissue disease or be idiopathic. While much attention was drawn into investigating and developing therapies related to the most well understood signaling pathways in PAH, in the last decade, a shift towards understanding the epigenetic mechanisms driving the disease occurred. In this review, we reflect on the different epigenetic regulatory factors that are associated with the pathology of RV remodeling, and on their relevance towards a better understanding of the disease and subsequently, the development of new and more efficient therapeutic strategies.

Effects of Different Types of Exercise Training on Pulmonary Arterial Hypertension: A Systematic Review

Pulmonary arterial hypertension (PAH) represents a chronic progressive disease characterized by high blood pressure in the pulmonary arteries leading to right heart failure. The disease has been a focus of medical research for many years due to its worse prognosis and limited treatment options. The aim of this study was to systematically assess the effects of different types of exercise interventions on PAH. Electronic databases were searched until July 2019. MEDLINE database was used as the predominant source for this paper. Studies with regards to chronic physical activity in adult PAH patients are compared on retrieving evidence on cellular, physiological, and psychological alterations in the PAH setting. Twenty human studies and 12 rat trials were identified. Amongst all studies, a total of 628 human subjects and 614 rats were examined. Regular physical activity affects the production of nitric oxygen and attenuates right ventricular hypertrophy. A combination of aerobic, anaerobic, and respiratory muscle training induces the strongest improvement in functional capacity indicated by an increase of 6 MWD and VO₂peak. In human studies, an increase of quality of life was found. Exercise training has an overall positive effect on the physiological and psychological components of PAH. Consequently, PAH patients should be encouraged to take part in regular exercise training programs.