Sex and haemodynamics in pulmonary arterial hypertension

Efficient uncertainty quantification in a spatially multiscale model of pulmonary arterial and venous hemodynamics

Pulmonary hypertension (PH) is a debilitating disease that alters the structure and function of both the proximal and distal pulmonary vasculature. This alters pressure-flow relationships in the pulmonary arterial and venous trees, though there is a critical knowledge gap in the relationships between proximal and distal hemodynamics in disease. Multiscale computational models enable simulations in both the proximal and distal vasculature. However, model inputs and measured data are inherently uncertain, requiring a full analysis of the sensitivity and uncertainty of the model. Thus, this study quantifies model sensitivity and output uncertainty in a spatially multiscale, pulse-wave propagation model of pulmonary hemodynamics. The model includes fifteen proximal arteries and twelve proximal veins, connected by a two-sided, structured tree model of the distal vasculature. We use polynomial chaos expansions to expedite sensitivity and uncertainty quantification analyses and provide results for both the proximal and distal vasculature. We quantify uncertainty in blood pressure, blood flow rate, wave intensity, wall shear stress, and cyclic stretch. The latter two are important stimuli for endothelial cell mechanotransduction. We conclude that, while nearly all the parameters in our system have some influence on model predictions, the parameters describing the density of the microvascular beds have the largest effects on all simulated quantities in both the proximal and distal arterial and venous circulations.

Contemporary Treatment of Pulmonary Arterial Hypertension: A U.S. Perspective

Pulmonary arterial hypertension (PAH) is a complex fatal condition that requires aggressive treatment with close monitoring. Significant progress has been made over the last three decades in the treatment of PAH, but, despite this progress, survival has remained unacceptably low. In the quest to improve survival, therapeutic interventions play a central role. In the last few years, there have been remarkable attempts to identify novel treatments. Finally, we have had a breakthrough with the discovery of the fourth treatment pathway in PAH. Activin signaling inhibition distinguishes itself as a potential antiproliferative intervention as opposed to the traditional therapies, which mediate their effect primarily by vasodilatation. With this novel treatment pathway, we stand at an important milestone with an exciting future ahead and the natural question of when to use an activin signaling inhibitor for the treatment of PAH. In this state-of-the-art review, we focus on the placement of this novel agent in the PAH treatment paradigm, based on the available evidence, with special focus on the U.S. patient population. This review also provides an expert opinion of the current treatment algorithm in important subgroups of patients with comorbidities from the U.S. perspective.

Sex-dependent remodeling of right ventricular function in a rat model of pulmonary arterial hypertension

Right ventricular (RV) function is an important prognostic indicator for pulmonary arterial hypertension (PAH), a vasculopathy that primarily and disproportionally affects women with distinct pre- and postmenopausal clinical outcomes. However, most animal studies have overlooked the impact of sex and ovarian hormones on RV remodeling in PAH. Here, we combined invasive measurements of RV hemodynamics and morphology with computational models of RV biomechanics in sugen-hypoxia (SuHx)-treated male, ovary-intact female, and ovariectomized female rats. Despite similar pressure overload levels, SuHx induced increases in end-diastolic elastance and passive myocardial stiffening, notably in male SuHx animals, corresponding to elevated diastolic intracellular calcium. Increases in end-systolic chamber elastance were largely explained by myocardial hypertrophy in male and ovary-intact female rats, whereas ovariectomized females exhibited contractility recruitment via calcium transient augmentation. Ovary-intact female rats primarily responded with hypertrophy, showing fewer myocardial mechanical alterations and less stiffening. These findings highlight sex-related RV remodeling differences in rats, affecting systolic and diastolic RV function in PAH.NEW & NOTEWORTHY Combining hemodynamic and morphological measurements from male, female, and ovariectomized female pulmonary arterial hypertension (PAH) rats revealed distinct adaptation mechanisms despite similar pressure overload. Males showed the most diastolic stiffening. Ovariectomized females had enhanced myocyte contractility and calcium transient upregulation. Ovary-intact females primarily responded with hypertrophy, experiencing milder passive myocardial stiffening and no changes in myocyte shortening. These findings suggest potential sex-specific pathways in right ventricular (RV) adaptation to PAH, with implications for targeted interventions.

Differences in presentation, diagnosis and management of heart failure in women. A scientific statement of the Heart Failure Association of the ESC

Despite the progress in the care of individuals with heart failure (HF), important sex disparities in knowledge and management remain, covering all the aspects of the syndrome, from aetiology and pathophysiology to treatment. Important distinctions in phenotypic presentation are widely known, but the mechanisms behind these differences are only partially defined. The impact of sex-specific conditions in the predisposition to HF has gained progressive interest in the HF community. Under-recruitment of women in large randomized clinical trials has continued in the more recent studies despite epidemiological data no longer reporting any substantial difference in the lifetime risk and prognosis between sexes. Target dose of medications and criteria for device eligibility are derived from studies with a large predominance of men, whereas specific information in women is lacking. The present scientific statement encompasses the whole scenario of available evidence on sex-disparities in HF and aims to define the most challenging and urgent residual gaps in the evidence for the scientific and clinical HF communities.

Dynamically stiffening biomaterials reveal age- and sex-specific differences in pulmonary arterial adventitial fibroblast activation

Respiratory diseases like pulmonary arterial hypertension (PAH) frequently exhibit sexual dimorphism. Female PAH patients are more susceptible to the disease but have increased survival rates. This phenomenon is known as the estrogen paradox, and the underlying mechanisms are not fully understood. During PAH progression in vivo, human pulmonary arterial adventitial fibroblasts (hPAAFs) differentiate into an activated phenotype. These cells produce excess, aberrant extracellular matrix proteins that stiffen the surrounding pulmonary arterial tissues. Here, we employed dynamic poly(ethylene glycol)-alpha methacrylate (PEGαMA)-based biomaterials to study how the age and sex of human serum influenced hPAAF activation in response to microenvironmental stiffening in vitro. Results showed female and male cells responded differently to increases in microenvironmental stiffness and serum composition. Male hPAAFs were less activated than female cells on soft hydrogels and more responsive to increases in microenvironmental stiffness regardless of serum composition. Female hPAAF activation followed this pattern only when cultured in younger (age < 50) female serum or when older (age ≥ 50) female serum was supplemented with estradiol. Otherwise, female hPAAF activation was relatively high on both soft and stiffened hydrogels, with little difference in activation between the two conditions. Collectively, these results suggest that it may be possible to model the estrogen paradox observed in PAH in vitro and that it is critical for researchers to report cell sex and serum source when conducting in vitro experimentation.

Investigating the "sex paradox" in pulmonary arterial hypertension: Results from the Pulmonary Hypertension Association Registry (PHAR)

BACKGROUND

Female sex is a significant risk factor for pulmonary arterial hypertension (PAH), yet males with PAH have worse survival - a phenomenon referred to as the "sex paradox" in PAH.

METHODS

All adult PAH patients in the Pulmonary Hypertension Association Registry (PHAR) with congruent sex and gender were included. Baseline differences in demographics, hemodynamics, functional parameters, and quality of life were assessed by sex. Kaplan-Meier survival analysis was used to evaluate survival by sex. Mediation analysis was conducted with Cox proportional hazards regression by comparing the unadjusted hazard ratios for sex before and after adjustment for covariates. The plausibility of collider-stratification bias was assessed by modeling how large an unmeasured factor would have to be to generate the observed sex-based mortality differences. Subgroup analysis was performed on idiopathic and incident patients.

RESULTS

Among the 1,891 patients included, 75% were female. Compared to men, women had less favorable hemodynamics, lower 6-minute walk distance, more PAH therapies, and worse functional class; however, sex-based differences were less pronounced when accounting for body surface area or expected variability by gender. On multivariate analysis, women had a 48% lower risk of death compared to men (Hazard Ratio 0.52, 95% Confidence interval 0.36 - 0.74, p < 0.001). Modeling found that under reasonable assumptions collider-stratification could account for sex-based differences in mortality.

CONCLUSIONS

In this large registry of PAH patients new to a care center, men had worse survival than women despite having more favorable baseline characteristics. Collider-stratification bias could account for the observed greater mortality among men.

Sex Differences in Pulmonary Hypertension and Associated Right Ventricular Dysfunction

Background

Prior studies have established the impact of sex differences on pulmonary arterial hypertension (PAH). However, it remains unclear whether these sex differences extend to other hemodynamic subtypes of pulmonary hypertension (PH).

Methods

We examined sex differences in PH and hemodynamic PH subtypes in a hospital-based cohort of individuals who underwent right heart catheterization between 2005-2016. We utilized multivariable linear regression to assess the association of sex with hemodynamic indices of RV function [PA pulsatility index (PAPi), RV stroke work index (RVSWI), and right atrial: pulmonary capillary wedge pressure ratio (RA:PCWP)]. We then used Cox regression models to examine the association between sex and clinical outcomes among those with PH.

Results

Among 5208 individuals with PH (mean age 64 years, 39% women), there was no significant sex difference in prevalence of PH overall. However, when stratified by PH subtype, 31% of women vs 22% of men had pre-capillary (P<0.001), 39% vs 51% had post-capillary (P=0.03), and 30% vs 27% had mixed PH (P=0.08). Female sex was associated with better RV function by hemodynamic indices, including higher PAPi and RVSWI, and lower RA:PCWP ratio (P<0.001 for all). Over 7.3 years of follow-up, female sex was associated with a lower risk of heart failure hospitalization (HR 0.83, CI 95% CI 0.74- 0.91, p value <0.001).

Conclusions

Across a broad hospital-based sample, more women had pre-capillary and more men had post-capillary PH. Compared with men, women with PH had better hemodynamic indices of RV function and a lower risk of HF hospitalization.

CLINICAL PERSPECTIVE

What Is New? Although sex differences have been explored in pulmonary arterial hypertension, sex differences across pulmonary hypertension (PH) in broader samples inclusive of all hemodynamic subtypes remain less well definedWe delineate sex differences in hemodynamic subtypes of PH and associated right ventricular function in a large, heterogenous, hospital-based sample of individuals who underwent right heart catheterizationSex has a significant impact on prevalence of PH across hemodynamic subtypes as well as associated RV function What Are the Clinical Implications? Understanding sex differences across different PH hemodynamic subtypes is paramount to refining risk stratification between men and womenFurther elucidating sex differences in associated RV function and clinical outcomes may aid in developing sex-specific therapies or management strategies to improve clinical outcomes.

Pulmonary arterial hypertension: Sex matters

Pulmonary arterial hypertension (PAH) is a complex disease of multifactorial origin. While registries have demonstrated that women are more susceptible to the disease, females with PAH have superior right ventricle (RV) function and a better prognosis than their male counterparts, a phenomenon referred to as the 'estrogen paradox'. Numerous pre-clinical studies have investigated the involvement of sex hormones in PAH pathobiology, often with conflicting results. However, recent advances suggest that abnormal estrogen synthesis, metabolism and signalling underpin the sexual dimorphism of this disease. Other sex hormones, such as progesterone, testosterone and dehydroepiandrosterone may also play a role. Several non-hormonal factor including sex chromosomes and epigenetics have also been implicated. Though the underlying pathophysiological mechanisms are complex, several compounds that modulate sex hormones levels and signalling are under investigation in PAH patients. Further elucidation of the estrogen paradox will set the stage for the identification of additional therapeutic targets for this disease.

Dynamically stiffening biomaterials reveal age- and sex-specific differences in pulmonary arterial adventitial fibroblast activation

Respiratory diseases like pulmonary arterial hypertension (PAH) frequently exhibit sexual dimorphism. Female PAH patients are more susceptible to the disease but have increased survival rates. This phenomenon is known as the estrogen paradox, and the underlying mechanisms are not fully understood. During PAH progression in vivo , human pulmonary arterial adventitial fibroblasts (hPAAFs) differentiate into an activated phenotype. These cells produce excess, aberrant extracellular matrix proteins that stiffen the surrounding pulmonary arterial tissues. Here, we employed dynamic poly(ethylene glycol)-alpha methacrylate (PEGαMA)-based biomaterials to study how the age and sex of human serum influenced hPAAF activation in response to microenvironmental stiffening in vitro . Results showed female and male cells responded differently to increases in microenvironmental stiffness and serum composition. Male hPAAFs were less activated than female cells on soft hydrogels and more responsive to increases in microenvironmental stiffness regardless of serum composition. Female hPAAF activation followed this pattern only when cultured in younger (age < 50) female serum or when older (age ≥ 50) female serum was supplemented with estradiol. Otherwise, female hPAAF activation was relatively high on both soft and stiffened hydrogels, with little difference in activation between the two conditions. Collectively, these results suggest that it may be possible to model the estrogen paradox observed in PAH in vitro and that it is critical for researchers to report cell sex and serum source when conducting in vitro experimentation.

Extrapulmonary manifestations of pulmonary arterial hypertension

INTRODUCTION

Extrapulmonary manifestations of pulmonary arterial hypertension (PAH) may play a critical pathobiological role and a deeper understanding will advance insight into mechanisms and novel therapeutic targets. This manuscript reviews our understanding of extrapulmonary manifestations of PAH.

AREAS COVERED

A group of experts was assembled and a complimentary PubMed search performed (October 2023 - March 2024). Inflammation is observed throughout the central nervous system and attempts at manipulation are an encouraging step toward novel therapeutics. Retinal vascular imaging holds promise as a noninvasive method of detecting early disease and monitoring treatment responses. PAH patients have gut flora alterations and dysbiosis likely plays a role in systemic inflammation. Despite inconsistent observations, the roles of obesity, insulin resistance and dysregulated metabolism may be illuminated by deep phenotyping of body composition. Skeletal muscle dysfunction is perpetuated by metabolic dysfunction, inflammation, and hypoperfusion, but exercise training shows benefit. Renal, hepatic, and bone marrow abnormalities are observed in PAH and may represent both end-organ damage and disease modifiers.

EXPERT OPINION

Insights into systemic manifestations of PAH will illuminate disease mechanisms and novel therapeutic targets. Additional study is needed to understand whether extrapulmonary manifestations are a cause or effect of PAH and how manipulation may affect outcomes.

Retrospective cohort study of pulmonary arterial hypertension associated with connective tissue disease effect on patients' prognosis

OBJECTIVE

The objectives of this study are to clarify clinical characteristics and recognize prognostic factors of CTD-PAH patients.

METHODS

A retrospective cohort study of consecutive patients with documented CTD-PAH diagnosis from Jan 2014 to Dec 2019 was conducted, the ones who have other comorbid conditions that cause PH were excluded. Survival functions were plotted using the Kaplan-Meier method. Univariable and multivariable Cox regression analysis was applied to determine the survival-related factors.

RESULTS

In 144 patients with CTD-PAH analyzed, the median sPAP value was 52.5 (44.0, 71.0) mmHg, the overall targeted drug usage rate was 55.6%, and only 27.5% patients were given combination. Twenty-four non-PAH-CTD patients with sPAP value were included as the control group. Compared with non-PAH-CTD groups, CTD-PAH patients had worse cardiac function, higher NT-pro BNP and γ-globulin level, and lower PaCO2 level. Compared with the mild PAH group, the moderate-severe PAH group had worse cardiac function; increased Hb, HCT, and NP-pro BNP level; and decreased PaO2. Kaplan-Meier analysis showed significant difference for survival among non-PAH-CTD, mild CTD-PAH, and moderate-severe CTD-PAH groups. The univariate analyses showed that Hb, pH, and Ln (NT-pro BNP) were identified as factors significantly associated with survival, and Hb and pH showed significant association with risk of death in the multivariate model. Kaplan-Meier analysis also showed that Hb > 109.0 g/L and pH > 7.457 affected CTD-PAH patients' survival significantly.

CONCLUSIONS

PAH is not rare in CTDs patients; PAH affects CTD patients' prognosis significantly. Higher Hb and pH were associated with an increased risk of death. Key Points • Pulmonary arterial hypertension affects connective tissue disease patients' prognosis significantly. • The significantly factors associated with survival is hemoglobin, pH, and Ln (NT-pro BNP).

Treatment of pulmonary arterial hypertension: recent progress and a look to the future

Pulmonary arterial hypertension (PAH) is a severe but treatable form of pre-capillary pulmonary hypertension caused by pulmonary vascular remodelling. As a result of basic science discoveries, randomised controlled trials, studies of real-world data, and the development of clinical practice guidelines, considerable progress has been made in the treatment options and outcomes for patients with PAH, underscoring the importance of seamless translation of information from bench to bedside and, ultimately, to patients. However, PAH still carries a high mortality rate, which emphasises the urgent need for transformative innovations in the field. In this Series paper, written by a group of clinicians, researchers, and a patient with PAH, we review therapeutic approaches and treatment options for PAH. We summarise current knowledge of the cellular and molecular mechanisms of PAH, with an emphasis on emerging treatable pathways and optimisation of current management strategies. In considering future directions for the field, our ambition is to identify therapies with the potential to stall or reverse pulmonary vascular remodelling. We highlight novel therapeutic approaches, the important role of patients as partners in research, and innovative approaches to PAH clinical trials.

Sex matters: the frequently overlooked importance of considering sex in computational models

Personalised medicine and the development of a virtual human or a digital twin comprises visions of the future of medicine. To realise these innovations, an understanding of the biology and physiology of all people are required if we wish to apply these technologies at a population level. Sex differences in health and biology is one aspect that has frequently been overlooked, with young white males being seen as the "average" human being. This has not been helped by the lack of inclusion of female cells and animals in biomedical research and preclinical studies or the historic exclusion, and still low in proportion, of women in clinical trials. However, there are many known differences in health between the sexes across all scales of biology which can manifest in differences in susceptibility to diseases, symptoms in a given disease, and outcomes to a given treatment. Neglecting these important differences in the development of any health technologies could lead to adverse outcomes for both males and females. Here we highlight just some of the sex differences in the cardio-respiratory systems with the goal of raising awareness that these differences exist. We discuss modelling studies that have considered sex differences and touch on how and when to create sex-specific models. Scientific studies should ensure sex differences are included right from the study planning phase and results reported using sex as a biological variable. Computational models must have sex-specific versions to ensure a movement towards personalised medicine is realised.

Characteristics, treatments and survival of pulmonary arterial hypertension associated with congenital heart disease in China: Insights from a national multicenter prospective registry

BACKGROUND

The purpose of this registry was to provide insights into the characteristics, treatments and survival of patients with PAH-CHD in China.

METHODS

Patients diagnosed with PAH-CHD were enrolled in this national multicenter prospective registry. Baseline and follow-up data on clinical characteristics, PAH-targeted treatments and survival were collected.

RESULTS

A total of 1060 PAH-CHD patients (mean age 31 years; 67.9% females) were included, with Eisenmenger syndrome (51.5%) being the most common form and atrial septal defects (37.3%) comprising the most frequent underlying defect. Approximately 33.0% of the patients were in World Health Organization functional class III to IV. The overall mean pulmonary arterial pressure and pulmonary vascular resistance were 67.1 (20.1) mm Hg and 1112.4 (705.9) dyn/s/cm5, respectively. PAH-targeted therapy was utilized in 826 patients (77.9%), and 203 patients (19.1%) received combination therapy. The estimated 1-, 3-, 5-, and 10-year survival rates of the overall cohort were 96.9%, 92.9%, 87.6% and 73.0%, respectively. Patients received combination therapy had significantly better survival than those with monotherapy (p = 0.016). NT-proBNP >1400 pg/ml, SvO2 ≤ 65% and Borg dyspnea index ≥ 3 and PAH-targeted therapy were independent predictors of mortality. Hemoglobin > 160g/L was a unique predictor for mortality in Eisenmenger syndrome.

CONCLUSIONS

Chinese PAH-CHD patients predominantly exhibit Eisenmenger syndrome and have significantly impaired exercise tolerance and right ventricular function at diagnosis, which are closely associated with long-term survival. PAH-targeted therapy including combination therapy showed a favorable effect on survival in PAH-CHD. The long-term survival of Chinese CHD-PAH patients remains to be improved.

Prognosis in Hispanic patient population with pulmonary arterial hypertension: An application of common risk stratification models

Pulmonary arterial hypertension (PAH) is a cardiovascular disease with high mortality rate. Current guidelines propose initiation and escalation of PAH-targeted treatment based on a goal-directed approach targeting hemodynamic, functional, and biochemical variables. This approach has been successfully validated in large Caucasian cohorts. However, given the low number of Hispanic patients enrolled in large PAH trials and registries, it is unknown if the same prognostic tools can be applied to this patient population. We analyzed a single-center outpatient cohort that consisted of 135 Hispanic patients diagnosed with PAH. Baseline characteristics were calculated based on COMPERA, COMPERA 2.0 and REVEAL 2.0 risk scores before the initiation of PAH-targeted therapies. The survival rate at 1 year after diagnosis was 88% for the entire cohort. The three established risk scores to predict PAH outcomes yielded similar results with reasonable discrimination of mortality in the different risk strata (all p < 0.001). Hispanic patients with PAH have a high mortality rate. Our analysis suggests that guideline proposed risk assessment at baseline yields important prognostic information in this patient population.

Sex and Gender in Lung Diseases and Sleep Disorders: A State-of-the-Art Review: Part 2

There is now ample evidence that differences in sex and gender contribute to the incidence, susceptibility, presentation, diagnosis, and clinical course of many lung diseases. Some conditions are more prevalent in women, such as pulmonary arterial hypertension and sarcoidosis. Some life stages-such as pregnancy-are unique to women and can affect the onset and course of lung disease. Clinical presentation may differ as well, such as the higher number of exacerbations experienced by women with cystic fibrosis (CF), more fatigue in women with sarcoidosis, and more difficulty in achieving smoking cessation. Outcomes such as mortality may be different as well, as indicated by the higher mortality in women with CF. In addition, response to therapy and medication safety may also differ by sex, and yet, pharmacogenomic factors are often not adequately addressed in clinical trials. Various aspects of lung/sleep biology and pathobiology are impacted by female sex and female reproductive transitions. Differential gene expression or organ development can be impacted by these biological differences. Understanding these differences is the first step in moving toward precision medicine for all patients. This article is the second part of a state-of-the-art review of specific effects of sex and gender focused on epidemiology, disease presentation, risk factors, and management of selected lung diseases. We review the more recent literature and focus on guidelines incorporating sex and gender differences in pulmonary hypertension, CF and non-CF bronchiectasis, sarcoidosis, restless legs syndrome and insomnia, and critical illness. We also provide a summary of the effects of pregnancy on lung diseases and discuss the impact of sex and gender on tobacco use and treatment of nicotine use disorder.

Pathophysiology and new advances in pulmonary hypertension

Pulmonary hypertension is a progressive and often fatal cardiopulmonary condition characterised by increased pulmonary arterial pressure, structural changes in the pulmonary circulation, and the formation of vaso-occlusive lesions. These changes lead to increased right ventricular afterload, which often progresses to maladaptive right ventricular remodelling and eventually death. Pulmonary arterial hypertension represents one of the most severe and best studied types of pulmonary hypertension and is consistently targeted by drug treatments. The underlying molecular pathogenesis of pulmonary hypertension is a complex and multifactorial process, but can be characterised by several hallmarks: inflammation, impaired angiogenesis, metabolic alterations, genetic or epigenetic abnormalities, influence of sex and sex hormones, and abnormalities in the right ventricle. Current treatments for pulmonary arterial hypertension and some other types of pulmonary hypertension target pathways involved in the control of pulmonary vascular tone and proliferation; however, these treatments have limited efficacy on patient outcomes. This review describes key features of pulmonary hypertension, discusses current and emerging therapeutic interventions, and points to future directions for research and patient care. Because most progress in the specialty has been made in pulmonary arterial hypertension, this review focuses on this type of pulmonary hypertension. The review highlights key pathophysiological concepts and emerging therapeutic directions, targeting inflammation, cellular metabolism, genetics and epigenetics, sex hormone signalling, bone morphogenetic protein signalling, and inhibition of tyrosine kinase receptors.

Baseline Sex Differences in Pulmonary Arterial Hypertension Randomized Clinical Trials

Rationale: Sex-based differences in pulmonary arterial hypertension (PAH) are known, but the contribution to disease measures is understudied. Objectives: We examined whether sex was associated with baseline 6-minute-walk distance (6MWD), hemodynamics, and functional class. Methods: We conducted a secondary analysis of participant-level data from randomized clinical trials of investigational PAH therapies conducted between 1998 and 2014 and provided by the U.S. Food and Drug Administration. Outcomes were modeled as a function of an interaction between sex and age or sex and body mass index (BMI), respectively, with generalized mixed modeling. Results: We included a total of 6,633 participants from 18 randomized clinical trials. A total of 5,197 (78%) were female, with a mean age of 49.1 years and a mean BMI of 27.0 kg/m2. Among 1,436 males, the mean age was 49.7 years, and the mean BMI was 26.4 kg/m2. The most common etiology of PAH was idiopathic. Females had shorter 6MWD. For every 1 kg/m2 increase in BMI for females, 6MWD decreased 2.3 (1.6-3.0) meters (P < 0.001), whereas 6MWD did not significantly change with BMI in males (0.31 m [-0.30 to 0.92]; P = 0.32). Females had lower right atrial pressure (RAP) and mean pulmonary artery pressure, and higher cardiac index than males (all P < 0.03). Age significantly modified the sex by RAP and mean pulmonary artery pressure relationships. For every 10-year increase in age, RAP was lower in males (0.5 mm Hg [0.3-0.7]; P < 0.001), but not in females (0.13 [-0.03 to 0.28]; P = 0.10). There was a significant decrease in pulmonary vascular resistance (PVR) with increasing age regardless of sex (P < 0.001). For every 1 kg/m2 increase in BMI, there was a 3% decrease in PVR for males (P < 0.001), compared with a 2% decrease in PVR in females (P < 0.001). Conclusions: Sexual dimorphism in subjects enrolled in clinical trials extends to 6MWD and hemodynamics; these relationships are modified by age and BMI. Sex, age, and body size should be considered in the evaluation and interpretation of surrogate outcomes in PAH.

Biomarkers in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a severe medical condition characterized by elevated pulmonary vascular resistance (PVR), right ventricular (RV) failure, and death in the absence of appropriate treatment. The progression and prognosis are strictly related to the etiology, biochemical parameters, and treatment response. The gold-standard test remains right-sided heart catheterization, but dynamic monitoring of systolic pressure in the pulmonary artery is performed using echocardiography. However, simple and easily accessible non-invasive assays are also required in order to monitor this pathology. In addition, research in this area is in continuous development. In recent years, more and more biomarkers have been studied and included in clinical guidelines. These biomarkers can be categorized based on their associations with inflammation, endothelial cell dysfunction, cardiac fibrosis, oxidative stress, and metabolic disorders. Moreover, biomarkers can be easily detected in blood and urine and correlated with disease severity, playing an important role in diagnosis, prognosis, and disease progression.

Testosterone deficiency independently predicts mortality in women with HFrEF: insights from the T.O.S.CA. registry

AIMS

Testosterone deficiency (TD) is associated with increased morbidity and mortality in heart failure with reduced ejection fraction (HFrEF). However, data in women are scanty. The aim of this study was to investigate the prognostic impact of TD on women with HFrEF.

METHODS

Among 480 patients prospectively enrolled in the T.O.S.CA. (Terapia Ormonale Scompenso CArdiaco) registry, a prospective, multicentre, nationwide, observational study, 94 women were included in the current analysis. The TD was defined as serum testosterone levels lower than 25 ng/dl. Data regarding clinical status, echocardiography, exercise performance, cardiovascular hospitalization, and survival after an average follow-up of 36 months were analysed.

RESULTS

Thirty patients (31.9%) displayed TD. TD was associated with lower tricuspid annular plane excursion (TAPSE) to pulmonary arterial systolic pressure PASP ratio (TAPSE/PASP) (P = 0.008), peak oxygen consumption (VO₂ peak) (P = 0.03) and estimated glomerular filtration rate (P < 0.001). TD was an independent predictor of the combined endpoint of all-cause mortality/cardiovascular hospitalization (HR: 10.45; 95% CI: 3.54-17.01; P = 0.001), all-cause mortality (HR: 8.33; 95%: 5.36-15.11; P = 0.039), and cardiovascular hospitalization (HR: 2.41; 95% CI: 1.13-4.50; P = 0.02).

CONCLUSIONS

One-third of women with HFrEF displays TD that impacts remarkably on their morbidity and mortality. TD is associated with a worse clinical profile including exercise capacity, right ventricular-pulmonary arterial coupling, and renal function. These findings lend support to an accurate profiling of women with HF, a problem often overlooked in clinical trials.

Sex Differences in Pulmonary Hypertension

Pulmonary hypertension (PH) includes multiple diseases that share as common characteristic an elevated pulmonary artery pressure and right ventricular involvement. Sex differences are observed in practically all causes of PH. The most studied type is pulmonary arterial hypertension (PAH) which presents a gender bias regarding its prevalence, prognosis, and response to treatment. Although this disease is more frequent in women, once affected they present a better prognosis compared to men. Even if estrogens seem to be the key to understand these differences, animal models have shown contradictory results leading to the birth of the estrogen paradox. In this review we will summarize the evidence regarding sex differences in experimental animal models and, very specially, in patients suffering from PAH or PH from other etiologies.

COMPERA 2.0: a refined four-stratum risk assessment model for pulmonary arterial hypertension

BACKGROUND

Risk stratification plays an essential role in the management of patients with pulmonary arterial hypertension (PAH). The current European guidelines propose a three-stratum model to categorise risk as low, intermediate or high, based on the expected 1-year mortality. However, with this model, most patients are categorised as intermediate risk. We investigated a modified approach based on four risk categories, with intermediate risk subdivided into intermediate-low and intermediate-high risk.

METHODS

We analysed data from the Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension (COMPERA), a European pulmonary hypertension registry, and calculated risk at diagnosis and first follow-up based on World Health Organization functional class, 6-min walk distance (6MWD) and serum levels of brain natriuretic peptide (BNP) or N-terminal pro-BNP (NT-proBNP), using refined cut-off values. Survival was assessed using Kaplan-Meier analyses, log-rank testing and Cox proportional hazards models.

RESULTS

Data from 1655 patients with PAH were analysed. Using the three-stratum model, most patients were classified as intermediate risk (76.0% at baseline and 63.9% at first follow-up). The refined four-stratum risk model yielded a more nuanced separation and predicted long-term survival, especially at follow-up assessment. Changes in risk from baseline to follow-up were observed in 31.1% of the patients with the three-stratum model and in 49.2% with the four-stratum model. These changes, including those between the intermediate-low and intermediate-high strata, were associated with changes in long-term mortality risk.

CONCLUSIONS

Modified risk stratification using a four-stratum model based on refined cut-off levels for functional class, 6MWD and BNP/NT-proBNP was more sensitive to prognostically relevant changes in risk than the original three-stratum model.

Secular and Regional Trends among Pulmonary Arterial Hypertension Clinical Trial Participants

Rationale: The population of patients with pulmonary arterial hypertension (PAH) has evolved over time from predominantly young White women to an older, more racially diverse and obese population. Whether these changes are reflected in clinical trials is not known. Objectives: To determine secular and regional trends among PAH trial participants. Methods: We performed a pooled cohort analysis using harmonized data from phase III clinical trials of PAH therapies submitted to the U.S. Food and Drug Administration. We used mixed-effects linear and logistic regression to assess regional differences in participant age, sex, body habitus, and hemodynamics over time. Results: A total of 6,599 participants were enrolled in 18 trials between 1998 and 2013; 78% were female. The mean age of participants in North America, Europe, and Latin America at the time of study start increased by 2.09 (95% confidence interval [CI], 0.67-3.51), 1.62 (95% CI, 0.24-3.00), and 4.75 (95% CI, 2.29-7.21) years per 5 years, respectively (P = 0.01). Body mass index at the time of study start increased by 0.72 kg/m2 per 5 years (95% CI, 0.44-0.99; P < 0.001) across all regions. Eighty-five percent of participants in early studies were non-Hispanic White, but this decreased over time to 70%. Ninety-seven percent of Asians and 74% of Hispanics in the sample were recruited from Asia and Latin America. Conclusions: Patients enrolled in more recent PAH therapy trials are older and more obese, mirroring the changing epidemiology of observational cohorts. However, these trends varied by geographic region. PAH cohorts remain predominantly female, presenting challenges for generalizability to male patients. Although the proportion of non-White participants increased over time, this was primarily through recruitment in Asia and Latin America.

Understanding the Pathobiology of Pulmonary Hypertension Due to Left Heart Disease

The development of pulmonary hypertension (PH) is common and has adverse prognostic implications in patients with heart failure due to left heart disease (LHD), and thus far, there are no known treatments specifically for PH-LHD, also known as group 2 PH. Diagnostic thresholds for PH-LHD, and clinical classification of PH-LHD phenotypes, continue to evolve and, therefore, present a challenge for basic and translational scientists actively investigating PH-LHD in the preclinical setting. Furthermore, the pathobiology of PH-LHD is not well understood, although pulmonary vascular remodeling is thought to result from (1) increased wall stress due to increased left atrial pressures; (2) hemodynamic congestion-induced decreased shear stress in the pulmonary vascular bed; (3) comorbidity-induced endothelial dysfunction with direct injury to the pulmonary microvasculature; and (4) superimposed pulmonary arterial hypertension risk factors. To ultimately be able to modify disease, either by prevention or treatment, a better understanding of the various drivers of PH-LHD, including endothelial dysfunction, abnormalities in vascular tone, platelet aggregation, inflammation, adipocytokines, and systemic complications (including splanchnic congestion and lymphatic dysfunction) must be further investigated. Here, we review the diagnostic criteria and various hemodynamic phenotypes of PH-LHD, the potential biological mechanisms underlying this disorder, and pressing questions yet to be answered about the pathobiology of PH-LHD.

Female rats are less prone to clinical heart failure than male rats in a juvenile rat model of right ventricular pressure load

Sex is increasingly emerging as determinant of right ventricular (RV) adaptation to abnormal loading conditions. It is unknown, however, whether sex-related differences already occur in childhood. Therefore, this study aimed to assess sex differences in a juvenile model of early RV pressure load by pulmonary artery banding (PAB) during transition from pre- to post-puberty. 3-weeks old rat pups (n=57, 30-45g) were subjected to PAB or sham surgery. Animals were sacrificed either before or after puberty (4 and 8 weeks post-surgery, respectively). Male PAB rats demonstrated failure to thrive already after 4 weeks, whereas females did not. After 8 weeks, female PAB rats showed less clinical symptoms of RV failure than male PAB rats. RV pressure-volume analysis demonstrated increased end-systolic elastance after 4 weeks in females only, and a trend toward preserved end-diastolic elastance in female PAB rats compared to males (p=0.055). Histology showed significantly less RV myocardial fibrosis in female compared to male PAB rats 8 weeks after surgery. Myosin heavy chain 7/6 ratio switch and calcineurin signaling were less pronounced in female PAB rats, compared to males. In this juvenile rat model of RV pressure load, female rats appeared to be less prone to clinical heart failure, compared to males. This was driven by increased RV contractility before puberty, and better preservation of diastolic function with less RV myocardial fibrosis after puberty. These findings show that RV adaptation to increased loading differs between sexes already before the introduction of pubertal hormones.

Sex differences in right ventricular adaptation to pressure overload in a rat model

With severe right ventricular (RV) pressure overload, women demonstrate better clinical outcomes compared with men. The mechanoenergetic mechanisms underlying this protective effect, and their dependence on female endogenous sex hormones, remain unknown. To investigate these mechanisms and their impact on RV systolic and diastolic functional adaptation, we created comparable pressure overload via pulmonary artery banding (PAB) in intact male and female Wistar rats and ovariectomized (OVX) female rats. At 8 wk after surgery, right heart catheterization demonstrated increased RV energy input [indexed pressure-volume area (iPVA)] in all PAB groups, with the greatest increase in intact females. PAB also increased RV energy output [indexed stroke or external work (iEW)] in all groups, again with the greatest increase in intact females. In contrast, PAB only increased RV contractility-indexed end-systolic elastance (iE_es)] in females. Despite these sex-dependent differences, no statistically significant effects were observed in the ratio of RV energy output to input (mechanical efficiency) or in mechanoenergetic cost to pump blood with pressure overload. These metrics were similarly unaffected by loss of endogenous sex hormones in females. Also, despite sex-dependent differences in collagen content and organization with pressure overload, decreases in RV compliance and relaxation time constant (tau Weiss) were not determined to be sex dependent. Overall, despite sex-dependent differences in RV contractile and fibrotic responses, RV mechanoenergetics for this degree and duration of pressure overload are comparable between sexes and suggest a homeostatic target.NEW & NOTEWORTHY Sex differences in right ventricular mechanical efficiency and energetic adaptation to increased right ventricular afterload were measured. Despite sex-dependent differences in contractile and fibrotic responses, right ventricular mechanoenergetic adaptation was comparable between the sexes, suggesting a homeostatic target.

Retinal vessel changes in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is classically considered an isolated small vessel vasculopathy of the lungs with peripheral pulmonary vascular obliteration. Systemic manifestations of PAH are increasingly acknowledged, but data remain limited. We hypothesized that retinal vascular changes occur in PAH. PAH subjects underwent retinal fluorescein angiography (FA) and routine disease severity measures were collected from the medical record. FA studies were analyzed using VESsel GENerational Analysis (VESGEN), a noninvasive, user‐interactive computer software that assigns branching generation to large and small vessels. FAs from controls (n = 8) and PAH subjects (n = 9) were compared. The tortuosity of retinal arteries was higher in PAH subjects compared to unmatched controls (1.17, 95% confidence interval: [1.14, 1.20] in PAH vs. 1.13, 95% CI: [1.12, 1.14] in controls, p = 0.01). Venous tortuosity was higher and more variable in PAH (1.17, 95% CI: [1.14, 1.20]) compared to controls (1.13, 95% CI: [1.12, 1.15]), p = 0.02. PAH subjects without connective tissue disease had the highest degree of retinal tortuosity relative to controls (arterial, p = 0.01; venous, p = 0.03). Younger PAH subjects had greater retinal arterial tortuosity, which attenuated with age and was not observed in controls. Retinal vascular parameters correlated with some clinical measures of disease in PAH subjects. In conclusion, PAH subjects exhibit higher retinal vascular tortuosity. Retinal vascular changes may track with pulmonary vascular disease progression. Use of FA and VESGEN may facilitate early, noninvasive detection of PAH.

Sex and gender in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare disease characterised by pulmonary vascular remodelling and elevated pulmonary pressure, which eventually leads to right heart failure and death. Registries worldwide have noted a female predominance of the disease, spurring particular interest in hormonal involvement in the disease pathobiology. Several experimental models have shown both protective and deleterious effects of oestrogens, suggesting that complex mechanisms participate in PAH pathogenesis. In fact, oestrogen metabolites as well as receptors and enzymes implicated in oestrogen signalling pathways and associated conditions such as BMPR2 mutation contribute to PAH penetrance more specifically in women. Conversely, females have better right ventricular function, translating to a better prognosis. Along with right ventricular adaptation, women tend to respond to PAH treatment differently from men. As some young women suffer from PAH, contraception is of particular importance, considering that pregnancy in patients with PAH is strongly discouraged due to high risk of death. When contraception measures fail, pregnant women need a multidisciplinary team-based approach. This article aims to review epidemiology, mechanisms underlying the higher female predominance, but better prognosis and the intricacies in management of women affected by PAH.

COMPERA 2.0: A refined 4-strata risk assessment model for pulmonary arterial hypertension

Background

Risk stratification plays an essential role in the management of patients with pulmonary arterial hypertension (PAH). The current European guidelines propose a three-stratum model to categorise risk as low, intermediate or high, based on the expected 1-year mortality. However, with this model, most patients are categorised as intermediate risk. We investigated a modified approach based on four risk categories, with intermediate risk subdivided into intermediate-low and intermediate-high risk.

Methods

We analysed data from the Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension (COMPERA), a European pulmonary hypertension registry, and calculated risk at diagnosis and first follow-up based on World Health Organization functional class, 6-min walk distance (6MWD) and serum levels of brain natriuretic peptide (BNP) or N-terminal pro-BNP (NT-proBNP), using refined cut-off values. Survival was assessed using Kaplan–Meier analyses, log-rank testing and Cox proportional hazards models.

Results

Data from 1655 patients with PAH were analysed. Using the three-stratum model, most patients were classified as intermediate risk (76.0% at baseline and 63.9% at first follow-up). The refined four-stratum risk model yielded a more nuanced separation and predicted long-term survival, especially at follow-up assessment. Changes in risk from baseline to follow-up were observed in 31.1% of the patients with the three-stratum model and in 49.2% with the four-stratum model. These changes, including those between the intermediate-low and intermediate-high strata, were associated with changes in long-term mortality risk.

Conclusions

Modified risk stratification using a four-stratum model based on refined cut-off levels for functional class, 6MWD and BNP/NT-proBNP was more sensitive to prognostically relevant changes in risk than the original three-stratum model.

COMPERA 2.0, a four-stratum risk assessment model based on refined cut-off levels for functional class, 6MWD and BNP/NT-proBNP was more sensitive to prognostically significant changes in risk than the original three-stratum modelhttps://bit.ly/3mzPKjA

Sex Differences, Estrogen Metabolism and Signaling in the Development of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a complex and devastating disease with a poor long-term prognosis. While women are at increased risk for developing PAH, they exhibit superior right heart function and higher survival rates than men. Susceptibility to disease risk in PAH has been attributed, in part, to estrogen signaling. In contrast to potential pathological influences of estrogen in patients, studies of animal models reveal estrogen demonstrates protective effects in PAH. Consistent with this latter observation, an ovariectomy in female rats appears to aggravate the condition. This discrepancy between observations from patients and animal models is often called the "estrogen paradox." Further, the tissue-specific interactions between estrogen, its metabolites and receptors in PAH and right heart function remain complex; nonetheless, these relationships are essential to characterize to better understand PAH pathophysiology and to potentially develop novel therapeutic and curative targets. In this review, we explore estrogen-mediated mechanisms that may further explain this paradox by summarizing published literature related to: (1) the synthesis and catabolism of estrogen; (2) activity and functions of the various estrogen receptors; (3) the multiple modalities of estrogen signaling in cells; and (4) the role of estrogen and its diverse metabolites on the susceptibility to, and progression of, PAH as well as their impact on right heart function.

Insulin Resistance Is Associated with Right Ventricular Dysfunction

RATIONALE

The effect of insulin resistance on left ventricular function is well documented, however less is known regarding its effect on the right ventricle (RV).

OBJECTIVES

To evaluate the association between insulin resistance and RV function by echocardiography in a cohort of adults without baseline cardiovascular disease.

METHODS

We performed a retrospective cohort study in the Multi-Ethnic Study of Atherosclerosis (MESA). Linear regression was used to examine the association between overall insulin resistance measured by the mean triglyceride to HDL cholesterol ratio (TG:HDL), and change in TG:HDL over time for each participant with echocardiographic RV function. Logistic regression was used to calculate the odds ratios of RV systolic and diastolic dysfunction.

RESULTS

Among 3,032 participants, higher mean TG:HDL was associated with lower (worse) absolute RV longitudinal strain (β -0.38; 95%CI -0.64, -0.13; p<0.01), tricuspid annular plane systolic excursion (TAPSE; β -0.05; 95%CI -0.07, -0.04; p<0.001) and higher odds of abnormal RV strain (OR 1.26; 95%CI 1.08, 1.47; p<0.01) and abnormal TAPSE (OR 1.31; 95%CI 1.14, 1.51; p<0.001). TG:HDL was also associated with lower tricuspid E/A ratio (β -0.03; 95%CI -0.04, -0.01; p<0.01), higher E/e' ratio (β 0.15; 95%CI 0.07, 0.23; p<0.001), and higher odds of graded RV diastolic dysfunction (OR 1.19; 95%CI 1.03, 1.39; p<0.05). These associations remained following multivariable adjustment.

CONCLUSIONS

Insulin resistance was associated with decreased RV systolic and diastolic function after adjusting for alternative causes of RV dysfunction, suggesting that insulin resistant individuals are at risk for early RV dysfunction, even in the absence of cardiovascular disease.

Cardiac and Pulmonary Vascular Remodeling in Endurance Open Water Swimmers Assessed by Cardiac Magnetic Resonance: Impact of Sex and Sport Discipline

Background: The cardiac response to endurance exercise has been studied previously, and recent reports have described the extension of this remodeling to the pulmonary vasculature. However, these reports have focused primarily on land-based sports and few data are available on exercise-induced cardio-pulmonary adaptation in swimming. Nor has the impact of sex on this exercise-induced cardio-pulmonary remodeling been studied in depth. The main aim of our study was to evaluate cardiac and pulmonary circulation remodeling in endurance swimmers. Among the secondary objectives, we evaluate the impact of sex and endurance sport discipline on this cardio-pulmonary remodeling promoted by exercise training.

Methods:Resting cardiovascular magnetic resonance imaging was performed in 30 healthy well-trained endurance swimmers (83.3% male) and in 19 terrestrial endurance athletes (79% male) to assess biventricular dimensions and function. Pulmonary artery dimensions and flow as well as estimates of pulmonary vascular resistance (PVR) were also evaluated.

Results:In relation to the reference parameters for the non-athletic population, male endurance swimmers had larger biventricular and pulmonary artery size (7.4 ± 1.0 vs. 5.9 ± 1.1 cm², p < 0.001) with lower biventricular ejection fraction (EF) (left ventricular (LV) EF: 58 ± 4.4 vs. 67 ± 4.5 %, p < 0.001; right ventricular (RV) EF: 60 ± 4 vs. 66 ± 6 %, p < 0.001), LV end-diastolic volume (EDV): 106 ± 11 vs. 80 ± 9 ml/m², p < 0.001; RV EDV: 101 ± 14 vs. 83 ± 12 ml/m², p < 0.001). Significantly larger LV volume and lower LV EF were also observed in female swimmers (LV EF: 60 ± 5.3 vs. 67 ± 4.6 %, p = 0.003; LV EDV: 90 ± 17.6 vs. 75± 8.7 ml/m², p = 0.002). Compared to terrestrial endurance athletes, swimmers showed increased LV indexed mass (75.0 ± 12.8 vs. 61.5 ± 10.0 g/m², p < 0.001). The two groups of endurance athletes had similar pulmonary artery remodeling.

Conclusions: Cardiac response to endurance swimming training implies an adaptation of both ventricular and pulmonary vasculature, as in the case of terrestrial endurance athletes. Cardio-pulmonary remodeling seems to be less extensive in female than in male swimmers.

Pulmonary Arterial Hypertension: Diagnosis, Treatment, and Novel Advances

The diagnosis and management of pulmonary arterial hypertension (PAH) includes several advances, such as a broader recognition of extrapulmonary vascular organ system involvement, validated point-of-care clinical assessment tools, and focus on the early initiation of multiple pharmacotherapeutics in appropriate patients. Indeed, a principal goal in PAH today is an early diagnosis for prompt initiation of treatment to achieve a minimal symptom burden; optimize the patient's biochemical, hemodynamic, and functional profile; and limit adverse events. To accomplish this end, clinicians must be familiar with novel risk factors and the revised hemodynamic definition for PAH. Fresh insights into the role of developmental biology (i.e., perinatal health) may also be useful for predicting incident PAH in early adulthood. Emergent or underused approaches to PAH management include a novel TGF-β ligand trap pharmacotherapy, remote pulmonary arterial pressure monitoring, next-generation imaging using inert gas-based magnetic resonance and other technologies, right atrial pacing, and pulmonary arterial denervation. These and other PAH state of the art advances are summarized here for the wider pulmonary medicine community.

Age-changes in right ventricular function-pulmonary circulation coupling: from pediatric to adult stage in 1899 healthy subjects. The RIGHT Heart International NETwork (RIGHT-NET)

The present study analyzes age-specific changes in RV function and RV-PA coupling in a large cohort of apparently healthy subjects with a wide age-range, to identify reference values and to study the influence of clinical and echocardiographic cofactors. 1899 Consecutive healthy subjects underwent a standardized transthoracic echocardiographic examination. Tricuspid annular plane systolic excursion (TAPSE) and systolic pulmonary artery pressure (SPAP) were measured. Ventriculo-arterial coupling was then inferred from the TAPSE/SPAP ratio. A quantile regression analysis was used to estimate quantiles 0.05, 0.10, 0.50 (median), 0.90, and 0.95 of TAPSE, SPAP and TAPSE/SPAP. The association between age and each of these values was determined. The mean age of the group was 45.2 ± 18.5 years (range 1 to 102 years), 971 were males. SPAP increased with age, whereas TAPSE and TAPSE/SPAP ratio decreased. Upon multivariate modeling, the most significant positive associations for TAPSE were body surface area (BSA) driven by the pediatric group, stroke volume (SV), E/A and negatively heart rate and E/e' ratio. SPAP was positively associated with increasing age, SV, E/A, E/e' and negatively with BSA. TAPSE/SPAP ratio was negatively associated with age, female sex, and E/e' and positively with BSA. A preserved relationship between TAPSE and SPAP was found across the different age groups. TAPSE, SPAP and TAPSE/SPAP demonstrate important trends and associations with advancing age, impaired diastolic function, affected by female sex and BSA However the relationship between TAPSE and SPAP is relatively well preserved across the age spectrum.

The Evolution of Risk Assessment in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a chronic debilitating disease that carries an unacceptably high morbidity and mortality rate despite improved survival with modern therapies. The combination of several modifiable and nonmodifiable variables yields a robust risk assessment across various available clinical calculators. The role of risk calculation is integral to managing PAH and aids in the timely referral to expert centers and potentially lung transplantation. Studies are ongoing to determine the role of risk calculators in the framework of clinical trials and to elucidate novel markers of high risk in PAH.

Sex and Gender Differences in Lung Disease

Sex differences in the anatomy and physiology of the respiratory system have been widely reported. These intrinsic sex differences have also been shown to modulate the pathophysiology, incidence, morbidity, and mortality of several lung diseases across the life span. In this chapter, we describe the epidemiology of sex differences in respiratory diseases including neonatal lung disease (respiratory distress syndrome, bronchopulmonary dysplasia) and pediatric and adult disease (including asthma, cystic fibrosis, idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease, lung cancer, lymphangioleiomyomatosis, obstructive sleep apnea, pulmonary arterial hypertension, and respiratory viral infections such as respiratory syncytial virus, influenza, and SARS-CoV-2). We also discuss the current state of research on the mechanisms underlying the observed sex differences in lung disease susceptibility and severity and the importance of considering both sex and gender variables in research studies' design and analysis.

Roles of Genetic Predisposition in the Sex Bias of Pulmonary Pathophysiology, as a Function of Estrogens : Sex Matters in the Prevalence of Lung Diseases

In addition to studies focused on estrogen mediation of sex-different regulation of systemic circulations, there is now increasing clinical relevance and research interests in the pulmonary circulation, in terms of sex differences in the morbidity and mortality of lung diseases such as inherent-, allergic- and inflammatory-based events. Thus, female predisposition to pulmonary artery hypertension (PAH) is an inevitable topic. To better understand the nature of sexual differentiation in the pulmonary circulation, and how heritable factors, in vivo- and/or in vitro-altered estrogen circumstances and changes in the live environment work in concert to discern the sex bias, this chapter reviews pulmonary events characterized by sex-different features, concomitant with exploration of how alterations of genetic expression and estrogen metabolisms trigger the female-predominant pathological signaling. We address the following: PAH (Sect.7.2) is characterized as an estrogenic promotion of its incidence (Sect. 7.2.2), as a function of specific germline mutations, and as an estrogen-elicited protection of its prognosis (Sect.7.2.1). More detail is provided to introduce a less recognized gene of Ephx2 that encodes soluble epoxide hydrolase (sEH) to degrade epoxyeicosatrienic acids (EETs). As a susceptible target of estrogen, Ephx2/sEH expression is downregulated by an estrogen-dependent epigenetic mechanism. Increases in pulmonary EETs then evoke a potentiation of PAH generation, but mitigation of its progression, a phenomenon similar to the estrogen-paradox regulation of PAH. Additionally, the female susceptibility to chronic obstructive pulmonary diseases (Sect. 7.3) and asthma (Sect.7.4), but less preference to COVID-19 (Sect. 7.5), and roles of estrogen in their pathogeneses are briefly discussed.

Potassium (K+) channels in the pulmonary vasculature: Implications in pulmonary hypertension Physiological, pathophysiological and pharmacological regulation

The large K⁺ channel functional diversity in the pulmonary vasculature results from the multitude of genes expressed encoding K⁺ channels, alternative RNA splicing, the post-transcriptional modifications, the presence of homomeric or heteromeric assemblies of the pore-forming α-subunits and the existence of accessory β-subunits modulating the functional properties of the channel. K⁺ channels can also be regulated at multiple levels by different factors controlling channel activity, trafficking, recycling and degradation. The activity of these channels is the primary determinant of membrane potential (Em) in pulmonary artery smooth muscle cells (PASMC), providing an essential regulatory mechanism to dilate or contract pulmonary arteries (PA). K⁺ channels are also expressed in pulmonary artery endothelial cells (PAEC) where they control resting Em, Ca²⁺ entry and the production of different vasoactive factors. The activity of K⁺ channels is also important in regulating the population and phenotype of PASMC in the pulmonary vasculature, since they are involved in cell apoptosis, survival and proliferation. Notably, K⁺ channels play a major role in the development of pulmonary hypertension (PH). Impaired K⁺ channel activity in PH results from: 1) loss of function mutations, 2) downregulation of its expression, which involves transcription factors and microRNAs, or 3) decreased channel current as a result of increased vasoactive factors (e.g., hypoxia, 5-HT, endothelin-1 or thromboxane), exposure to drugs with channel-blocking properties, or by a reduction in factors that positively regulate K⁺ channel activity (e.g., NO and prostacyclin). Restoring K⁺ channel expression, its intracellular trafficking and the channel activity is an attractive therapeutic strategy in PH.

17β-Estradiol and estrogen receptor α protect right ventricular function in pulmonary hypertension via BMPR2 and apelin

Women with pulmonary arterial hypertension (PAH) exhibit better right ventricular (RV) function and survival than men; however, the underlying mechanisms are unknown. We hypothesized that 17β-estradiol (E2), through estrogen receptor α (ER-α), attenuates PAH-induced RV failure (RVF) by upregulating the procontractile and prosurvival peptide apelin via a BMPR2-dependent mechanism. We found that ER-α and apelin expression were decreased in RV homogenates from patients with RVF and from rats with maladaptive (but not adaptive) RV remodeling. RV cardiomyocyte apelin abundance increased in vivo or in vitro after treatment with E2 or ER-α agonist. Studies employing ER-α-null or ER-β-null mice, ER-α loss-of-function mutant rats, or siRNA demonstrated that ER-α is necessary for E2 to upregulate RV apelin. E2 and ER-α increased BMPR2 in pulmonary hypertension RVs and in isolated RV cardiomyocytes, associated with ER-α binding to the Bmpr2 promoter. BMPR2 is required for E2-mediated increases in apelin abundance, and both BMPR2 and apelin are necessary for E2 to exert RV-protective effects. E2 or ER-α agonist rescued monocrotaline pulmonary hypertension and restored RV apelin and BMPR2. We identified what we believe to be a novel cardioprotective E2/ER-α/BMPR2/apelin axis in the RV. Harnessing this axis may lead to novel RV-targeted therapies for PAH patients of either sex.

Association of premature menopause with incident pulmonary hypertension: A cohort study

Background

Several forms of pulmonary hypertension (PH) disproportionately affect women. Animal and human studies suggest that estradiol exerts mixed effects on the pulmonary vasculature. Whether premature menopause represents a risk factor for PH is unknown.

Methods and findings

In this cohort study, women in the UK Biobank aged 40–69 years who were postmenopausal and had complete data available on reproductive history were included. Premature menopause, defined as menopause occurring before age 40 years. Postmenopausal women without premature menopause served as the reference group. The primary outcome was incident PH, ascertained by appearance of a qualifying ICD code in the participant’s UK Biobank study record. Of 136,715 postmenopausal women included, 5,201 (3.8%) had premature menopause. Participants were followed up for a median of 11.1 (interquartile range 10.5–11.8) years. The primary outcome occurred in 38 women (0.73%) with premature menopause and 409 (0.31%) without. After adjustment for age, race, ever-smoking, body-mass index, systolic blood pressure, antihypertensive medication use, non-high-density lipoprotein cholesterol, cholesterol-lowering medication use, C-reactive protein, prevalent type 2 diabetes, obstructive sleep apnea, heart failure, mitral regurgitation, aortic stenosis, venous thromboembolism, forced vital capacity (FVC), the forced expiratory volume in 1 second-to-FVC ratio, use of menopausal hormone therapy, and hysterectomy status, premature menopause was independently associated with PH (hazard ratio 2.13, 95% CI 1.31–3.23, P<0.001). In analyses of alternate menopausal age thresholds, risk of PH appeared to increase progressively with younger age at menopause (P_trend <0.001), with 4.8-fold risk in women with menopause before age 30 years (95% CI 1.82–12.74, P = 0.002). Use of menopausal hormone therapy did not modify the association of premature menopause with PH.

Conclusions

Premature menopause may represent an independent risk factor for PH in women. Further investigation of the role of sex hormones in PH is needed in animal and human studies to elucidate pathobiology and identify novel therapeutic targets.

Sex Differences in Pulmonary Hypertension

Pulmonary arterial hypertension (PAH) occurs in women more than men whereas survival in men is worse than in women. In recent years, much research has been carried out to understand these sex differences in PAH. This article discusses clinical and preclinical studies that have investigated the influences of sex, serotonin, obesity, estrogen, estrogen synthesis, and estrogen metabolism on bone morphogenetic protein receptor type II signaling, the pulmonary circulation and right ventricle in both heritable and idiopathic pulmonary hypertension.

Sex difference in pulmonary hypertension in the evaluation by exercise echocardiography

Male patients with pulmonary hypertension have poor survival than their female counterparts. Poor right ventricular function in men may be one of the major determinants of poor prognosis. This study aimed to investigate the difference in hemodynamics during exercise between men and women by exercise echocardiography. Consecutive patients with pulmonary hypertension who underwent right heart catheterization were enrolled, and survival was analyzed. In patients who underwent exercise echocardiography, the change in tricuspid regurgitation pressure gradient during exercise was calculated at multiple stages (low-, moderate-, and high-load exercise), and the mortality was also recorded. In a total of 93 patients, although there were no differences in pulmonary artery pressure and vascular resistance between sexes, male patients showed poor survival. In patients with exercise echocardiography, change in tricuspid regurgitation pressure gradient at low-load (25 W) exercise was significantly lower in men, although that at maximum-load exercise was not different between men and women. In the Kaplan-Meier analysis, in a median follow-up duration of 1760 days, male patients and those with lower change in tricuspid regurgitation pressure gradient at low-load exercise showed poorer survival (P = 0.002 and 0.026, respectively). In the Cox proportional hazards analysis, the change in tricuspid regurgitation pressure gradient at low-load exercise was independently associated with poor survival after adjustment for age and sex. In conclusion, a lower change in tricuspid regurgitation pressure gradient at low-load exercise was observed in male patients and was a prognostic marker, which may be associated, at least in part, with poorer prognosis in male patients with pulmonary hypertension.

Targeted Drugs for Treatment of Pulmonary Arterial Hypertension: Past, Present, and Future Perspectives

Pulmonary arterial hypertension (PAH) is a devastating disease that can lead to right ventricular failure and premature death. Although approved drugs have been shown to be safe and effective, PAH remains a severe clinical condition, and the long-term survival of patients with PAH is still suboptimal. Thus, potential therapeutic targets and new agents to treat PAH are urgently needed. In recent years, a variety of related pathways and potential therapeutic targets have been found, which brings new hope for PAH therapy. In this perspective, not only are the marketed drugs used to treat PAH summarized but also the recently developed novel pharmaceutical therapies currently in clinical trials are discussed. Furthermore, the advances in natural products as potential treatment for PAH are also updated.

Molecular mechanisms of right ventricular dysfunction in pulmonary arterial hypertension: focus on the coronary vasculature, sex hormones, and glucose/lipid metabolism

Pulmonary arterial hypertension (PAH) is a rare, life-threatening condition characterized by dysregulated metabolism, pulmonary vascular remodeling, and loss of pulmonary vascular cross-sectional area due to a variety of etiologies. Right ventricular (RV) dysfunction in PAH is a critical mediator of both long-term morbidity and mortality. While combinatory oral pharmacotherapy and/or intravenous prostacyclin aimed at decreasing pulmonary vascular resistance (PVR) have improved clinical outcomes, there are currently no treatments that directly address RV failure in PAH. This is, in part, due to the incomplete understanding of the pathogenesis of RV dysfunction in PAH. The purpose of this review is to discuss the current understanding of key molecular mechanisms that cause, contribute and/or sustain RV dysfunction, with a special focus on pathways that either have led to or have the potential to lead to clinical therapeutic intervention. Specifically, this review discusses the mechanisms by which vessel loss and dysfunctional angiogenesis, sex hormones, and metabolic derangements in PAH directly contribute to RV dysfunction. Finally, this review discusses limitations and future areas of investigation that may lead to novel understanding and therapeutic interventions for RV dysfunction in PAH.

Sex Differences in Portopulmonary Hypertension

BACKGROUND

Portopulmonary hypertension (POPH), pulmonary arterial hypertension that develops in the setting of portal hypertension, can lead to right-sided heart failure and death. Being female is a known risk factor for POPH, but little is known about the effect of sex on clinical manifestations, hemodynamics, treatment response, and survival.

RESEARCH QUESTION

We sought to characterize sex differences in clinical characteristics, pulmonary hemodynamics, treatment response, and survival in patients with POPH.

STUDY DESIGN AND METHODS

We performed a retrospective cohort study of adult candidates for liver transplant (LT) who had POPH within the Organ Procurement and Transplantation Network database. Females and males were compared. Multivariate regression was performed to assess the association between sex and pulmonary vascular resistance (PVR) and survival. Patients were also stratified by age (50 years) to determine how age modifies the relationship between sex and hemodynamics and survival.

RESULTS

We included 190 adults (103 male, 87 female). Compared with men, women had a lower model for end-stage liver disease (MELD) score (12.1± 4.2 vs 13.8 ± 4.9; P = .01) and were more likely to have autoimmune liver disease. Women had a higher baseline PVR (610.6 ± 366.6 vs 461.0 ± 185.3 dynes-s-cm^-5; P < .001) and posttreatment PVR (244.6 ± 119.5 vs 202.0 ± 87.7 dynes-s-cm^-5; P = .008) and a greater treatment response (ΔPVR) (-359.3 ± 381.9 vs -260.2 ± 177.3 dynes-s-cm^-5; P = .03). In multivariate analysis, female sex (or gender) remained associated with a higher baseline PVR (P = .008). Women and men had overall similar survival (P > .05). When patients were stratified by age, being female was independently associated with worse waiting list survival after adjusting for MELD and PVR in younger patients (HR, 6.61; 95% CI, 1.25-35.08; P = .03) but not in older patients.

INTERPRETATION

Compared with male candidates, female candidates for LT who had POPH had a higher PVR and lower MELD score and were more likely to have autoimmune liver disease. Women and men had similar overall survival, but female sex (or gender) was associated with worse survival in younger patients.

Idiopathic pulmonary arterial hypertension and co-existing lung disease: is this a new phenotype?

Patients classified as idiopathic pulmonary arterial hypertension (defined as Group 1 on European Respiratory Society (ERS)/European Cardiac Society (ESC) criteria) may have evidence of minor co-existing lung disease on thoracic computed tomography. We hypothesised that these idiopathic pulmonary arterial hypertension patients (IPAH _{lung disease}) are a separate subgroup of idiopathic pulmonary arterial hypertension with different phenotype and outcome compared with idiopathic pulmonary arterial hypertension patients without co-existing lung disease (IPAH _{no lung disease}). Patients with ‘IPAH _{lung disease}’ have been eligible for all clinical trials of Group 1 patients because they have normal clinical examination and normal spirometry but we wondered whether they responded to treatment and had similar survival to patients with ‘IPAH _{no lung disease}’. We described the outcome of the cohort of patients with ‘IPAH _{no lung disease}’ in a previous paper. Here, we have compared incident ‘IPAH _{lung disease}’ patients with ‘IPAH _{no lung disease}’ patients diagnosed concurrently in all eight Pulmonary Hypertension centres in the UK and Ireland between 2001–2009. Compared with ‘IPAH _{no lung disease}’ (n = 355), ‘IPAH _{lung disease}’ patients (n = 137) were older, less obese, predominantly male, more likely to be current/ex-smokers and had lower six-minute walk distance, lower % predicted diffusion capacity for carbon monoxide, lower mean pulmonary arterial pressure and lower pulmonary vascular resistance index. After three months of pulmonary hypertension-targeted treatment, six-minute walk distance improved equally in ‘IPAH _{lung disease}’ and ‘IPAH _{no lung disease}’. However, survival of ‘IPAH _{lung disease}’ was lower than ‘IPAH _{no lung disease}’ (one year survival: 72% compared with 93%). This survival was significantly worse in ‘IPAH _{lung disease}’ even after adjusting for age, gender, smoking history, comorbidities and haemodynamics. ‘IPAH _{lung disease}’ patients had similar short-term improvement in six-minute walk distance with anti-pulmonary arterial hypertension therapy but worse survival compared with ‘IPAH _{no lung disease}’ patients. This suggests that ‘IPAH _{lung disease}’ are a separate phenotype and should not be lumped with ‘IPAH _{no lung disease}’ in clinical trials of Group 1 pulmonary arterial hypertension.

Gender differences in pulmonary arterial hypertension patients with BMPR2 mutation: a meta-analysis

OBJECTIVE

To investigate the differences in the proportions of BMPR2 mutations in familial hereditary pulmonary arterial hypertension (HPAH) and idiopathic pulmonary arterial hypertension (IPAH) between males and females and the relationship between BMPR2 mutation and PAH severity.

METHODS

A computer was used to search the electronic Cochrane Library, PubMed/MEDLINE, and EMBASE databases for clinical trials containing information on the relationship between PAH prognosis and BMPR2 mutations through March 2019. After obtaining the data, a meta-analysis was performed using Review Manager Version 5.3 and Stata.

RESULTS

A meta-analysis was performed on 17 clinical trials (2198 total patients: 644 male, 1554 female). The results showed that among patients with HPAH and IPAH, the BMPR2 mutation rate is higher in male than in female patients [male group (224/644, 34.78%), female group (457/1554, 29.41%), OR = 1.30, 95% CI: 1.06~1.60, P = 0.01, I² = 10%]. Furthermore, haemodynamic and functional parameters were more severe in IPAH and HPAH patients with BMPR2 mutations than in those without, and those with BMPR2 mutation were diagnosed at a younger age. The risk of death or transplantation was higher in PAH patients with BMPR2 mutations than in those without (OR = 2.51, 95% CI: 1.29~3.57, P = 0.003, I² = 24%). Furthermore, the difference was significant only in male patients (OR = 5.58, 95% CI: 2.16~14.39, P = 0.0004, I² = 0%) and not in female patients (OR = 1.41, 95% CI: 0.75~2.67, P = 0.29, I² = 0%).

CONCLUSION

Among patients with HPAH and IPAH, men are more likely to have BMPR2 mutations, which may predict more severe PAH indications and prognosis.

Sex, Gender, and Sex Hormones in Pulmonary Hypertension and Right Ventricular Failure

Pulmonary hypertension (PH) encompasses a syndrome of diseases that are characterized by elevated pulmonary artery pressure and pulmonary vascular remodeling and that frequently lead to right ventricular (RV) failure and death. Several types of PH exhibit sexually dimorphic features in disease penetrance, presentation, and progression. Most sexually dimorphic features in PH have been described in pulmonary arterial hypertension (PAH), a devastating and progressive pulmonary vasculopathy with a 3-year survival rate <60%. While patient registries show that women are more susceptible to development of PAH, female PAH patients display better RV function and increased survival compared to their male counterparts, a phenomenon referred to as the "estrogen paradox" or "estrogen puzzle" of PAH. Recent advances in the field have demonstrated that multiple sex hormones, receptors, and metabolites play a role in the estrogen puzzle and that the effects of hormone signaling may be time and compartment specific. While the underlying physiological mechanisms are complex, unraveling the estrogen puzzle may reveal novel therapeutic strategies to treat and reverse the effects of PAH/PH. In this article, we (i) review PH classification and pathophysiology; (ii) discuss sex/gender differences observed in patients and animal models; (iii) review sex hormone synthesis and metabolism; (iv) review in detail the scientific literature of sex hormone signaling in PAH/PH, particularly estrogen-, testosterone-, progesterone-, and dehydroepiandrosterone (DHEA)-mediated effects in the pulmonary vasculature and RV; (v) discuss hormone-independent variables contributing to sexually dimorphic disease presentation; and (vi) identify knowledge gaps and pathways forward. © 2020 American Physiological Society. Compr Physiol 10:125-170, 2020.