Obesity in Pulmonary Arterial Hypertension (PAH): The Pulmonary Hypertension Association Registry (PHAR)

Obstructive Sleep Apnea, Obesity Hypoventilation Syndrome, and Pulmonary Hypertension: A State-of-the-Art Review

The pathophysiological interplay between sleep-disordered breathing (SDB) and pulmonary hypertension (PH) is complex and can involve a variety of mechanisms by which SDB can worsen PH. These mechanistic pathways include wide swings in intrathoracic pressure while breathing against an occluded upper airway, intermittent and/or sustained hypoxemia, acute and/or chronic hypercapnia, and obesity. In this review, we discuss how the downstream consequences of SDB can adversely impact PH, the challenges in accurately diagnosing and classifying PH in the severely obese, and review the limited literature assessing the effect of treating obesity, obstructive sleep apnea, and obesity hypoventilation syndrome on PH.

Diabetes mellitus, glycemic traits, SGLT2 inhibition, and risk of pulmonary arterial hypertension: A Mendelian randomization study

This study aimed to investigate the causal role of diabetes mellitus (DM), glycemic traits, and sodium-glucose cotransporter 2 (SGLT2) inhibition in pulmonary arterial hypertension (PAH). Utilizing a two-sample two-step Mendelian randomization (MR) approach, we determined the causal influence of DM and glycemic traits (including insulin resistance, glycated hemoglobin, and fasting insulin and glucose) on the risk of PAH. Moreover, we examined the causal effects of SGLT2 inhibition on the risk of PAH. Genetic proxies for SGLT2 inhibition were identified as variants in the SLC5A2 gene that were associated with both levels of gene expression and hemoglobin A1c. Results showed that genetically inferred DM demonstrated a causal correlation with an increased risk of PAH, exhibiting an odds ratio (OR) of 1.432, with a 95% confidence interval (CI) of 1.040-1.973, and a p-value of 0.028. The multivariate MR analysis revealed comparable outcomes after potential confounders (OR = 1.469, 95%CI = 1.021-2.115, p = 0.038). Moreover, genetically predicted SGLT2 inhibition was causally linked to a reduced risk of PAH (OR = 1.681*10-7, 95%CI = 7.059*10-12-0.004, p = 0.002). Therefore, our study identified the suggestively causal effect of DM on the risk of PAH, and SGLT2 inhibition may be a potential therapeutic target in patients with PAH.

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.

Pulmonary hypertension and insulin resistance: a mechanistic overview

Pulmonary arterial hypertension (PAH) is a vascular remodeling disease, characterized by increased blood pressure levels in pulmonary circulation, leading to a restriction in the circulation flow and heart failure. Although the emergence of new PAH therapies has increased survival rates, this disease still has a high mortality and patients that receive diagnosis die within a few years. The pathogenesis of PAH involves multiple pathways, with a complex interaction of local and distant cytokines, hormones, growth factors, and transcription factors, leading to an inflammation that changes the vascular anatomy in PAH patients. These abnormalities involve more than just the lungs, but also other organs, and between these affected organs there are different metabolic dysfunctions implied. Recently, several publications demonstrated in PAH patients a disturbance in glucose metabolism, demonstrated by higher levels of glucose, insulin, and lipids in those patients. It is possible that a common molecular mechanism can have a significant role in this connection. In this regard, this narrative review intends to focus on the recent papers that mainly discuss the molecular determinants between insulin resistance (IR) associated PAH, which included obesity subclinical inflammation induced IR, PPAR gamma and Adiponectin, BMPR2, mitochondrial dysfunction and endoplasmic reticulum stress. Therefore, the following review will summarize some of the existing data for IR associated PAH, focusing on the better understanding of PAH molecular mechanisms, for the development of new translational therapies.

Effect of Obesity on Mortality in Pulmonary Hypertension-A Systematic Review and Meta-Analysis

Obesity is reported to have a protective effect on mortality in pulmonary hypertension (PH), a phenomenon known as obesity paradox. However, the data are conflicting, with some studies showing decreased mortality while other studies found no effect of obesity on mortality. Therefore, we performed a systematic review and meta-analysis to examine whether there is an association between obesity and mortality in PH. Only patients with PH diagnosed by right heart catheterization were included. We also performed a sub-group analysis of subjects with pre-capillary PH only. A total of six studies met the inclusion criteria, with a sample size of 13,987 patients. Obese subjects had lower mortality compared to non-obese subjects in the combined pre- and post-capillary PH group (hazard ratio 0.79, 95% CI 0.66-0.95, p = 0.01). While obesity was associated with reduction in mortality in the pre-capillary PH group (hazard ratio 0.77, 95% CI 0.60 to 0.98, p = 0.03), this was not uniform across all studies.

Premorbid weight in pulmonary arterial hypertension

Relationships between obesity and outcomes in pulmonary arterial hypertension (PAH) are complex. Previous work suggested obesity, occurring alongside PAH, may be associated with better survival. In our work, we suggest obesity prior to PAH development is associated with worse survival. This may add a novel temporal element to the "obesity-paradox."

Pulmonary Hypertension: A Contemporary Review

Major advances in pulmonary arterial hypertension, pulmonary hypertension (PH) associated with lung disease, and chronic thromboembolic PH cast new light on the pathogenetic mechanisms, epidemiology, diagnostic approach, and therapeutic armamentarium for pulmonary vascular disease. Here, we summarize key basic, translational, and clinical PH reports, emphasizing findings that build on current state-of-the-art research. This review includes cutting-edge progress in translational pulmonary vascular biology, with a guide to the diagnosis of patients in clinical practice, incorporating recent PH definition revisions that continue emphasis on early detection of disease. PH management is reviewed including an overview of the evolving considerations for the approach to treatment of PH in patients with cardiopulmonary comorbidities, as well as a discussion of the groundbreaking sotatercept data for the treatment of pulmonary arterial hypertension.

Role of Gastroesophageal Reflux Disease in Morbidity and Mortality for Patients Admitted With Pulmonary Hypertension

INTRODUCTION

The association between gastroesophageal reflux disease (GERD) and morbidity and mortality in patients with pulmonary arterial hypertension (PH) is unknown. Our objective was to examine the difference in socio-demographics, comorbidities, and morbidity/mortality in PH patients also diagnosed with GERD, compared to PH patients without GERD.

METHODS

We performed a retrospective cross-sectional study of the large U.S. National Inpatient Sample identifying patients with a primary diagnosis of primary pulmonary hypertension (PH). All patients ≥ 18 years old that were admitted with a primary diagnosis of PH from January 1, 2001, to December 31, 2013, in the NIS database were included. We analyzed the socio-demographic and clinical comorbidities in PH patients with and without GERD. We investigated the predictors for complications of PH and differences in hospital utilization in this population.

RESULTS

PH patients with GERD were more likely to be older than 18-29 years. They were more likely to be Caucasian and female and less likely to be part of the top 75% median income compared to the bottom 25%. Patients with GERD were more likely insured with Medicare or private insurance but less likely to have Medicaid or be uninsured. Patients were more likely to be obese, and have asthma, chronic bronchitis, obstructive sleep apnea, hypertension, and hypothyroidism but were less likely to have diabetes or a history of alcohol use. PH Patients with GERD were less likely to have myocardial infarctions, cardiac arrests, pulmonary embolisms, pulmonary hemorrhages, cardiac interventions, acute respiratory failure, acute renal failure, or urinary tract infections compared to those without GERD. Patients with GERD were, however, more likely to have acute heart failure exacerbations and aspiration pneumonia. Patients with a diagnosis of GERD had lower mortality, length of stay (LOS), and hospital costs compared to their counterparts.

CONCLUSIONS

The concomitant presence of GERD is associated with fewer adverse outcomes in patients with PH. Though it is well understood that treatment of GERD is beneficial for lung disease, the exact role of GERD in PH has not been identified. This study helps characterize the important role appropriately treated GERD may play in preventing morbidity and mortality due to PH.

Respiratory complications of obesity: from early changes to respiratory failure

Obesity is a significant and increasingly common cause of respiratory compromise. It causes a decrease in static and dynamic pulmonary volumes. The expiratory reserve volume is one of the first to be affected. Obesity is associated with reduced airflow, increased airway hyperresponsiveness, and an increased risk of developing pulmonary hypertension, pulmonary embolism, respiratory tract infections, obstructive sleep apnoea and obesity hypoventilation syndrome. The physiological changes caused by obesity will eventually lead to hypoxic or hypercapnic respiratory failure. The pathophysiology of these changes includes a physical load of adipose tissue on the respiratory system and a systemic inflammatory state. Weight loss has clear, well-defined benefits in improving respiratory and airway physiology in obese individuals.

BMI and Treatment Response in Patients With Pulmonary Arterial Hypertension

Background

Obesity is increasingly prevalent in pulmonary arterial hypertension (PAH) but is associated with improved survival, creating an “obesity paradox” in PAH. It is unknown if the improved outcomes could be attributable to obese patients deriving a greater benefit from PAH therapies.

Research Question

Does BMI modify treatment effectiveness in PAH?

Study Design and Methods

Using individual participant data, a meta-analysis was conducted of phase III, randomized, placebo-controlled trials of treatments for PAH submitted for approval to the U.S. Food and Drug Administration from 2000 to 2015. Primary outcomes were change in 6-min walk distance (6MWD) and World Health Organization (WHO) functional class.

Results

A total of 5,440 participants from 17 trials were included. Patients with overweight and obesity had lower baseline 6MWD and were more likely to be WHO functional class III or IV. Treatment was associated with a 27.01-m increase in 6MWD (95% CI, 21.58-32.45; P < .001) and lower odds of worse WHO functional class (OR, 0.58; 95% CI, 0.48-0.70; P < .001). For every 1 kg/m² increase in BMI, 6MWD was reduced by 0.66 m (P = .07); there was no significant effect modification of treatment response in 6MWD according to BMI (P for interaction = .34). Higher BMI was not associated with odds of WHO functional class at end of follow-up; however, higher BMI attenuated the treatment response such that every 1 kg/m² increase in BMI increased odds of worse WHO functional class by 3% (OR, 1.03; P for interaction = .06).

Interpretation

Patients with overweight and obesity had lower baseline 6MWD and worse WHO functional class than patients with normal weight with PAH. Higher BMI did not modify the treatment response for change in 6MWD, but it attenuated the treatment response for WHO functional class. PAH trials should include participants representative of all weight groups to allow for assessment of treatment heterogeneity and mechanisms.

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.

The Association of Body Mass Index With Mortality Among Pulmonary Hypertension Patients: A Systematic Review and Meta-Analysis of Cohort Studies

Objective

To run a systematic review and meta-analysis of related studies on body mass index (BMI) and the risk of death among pulmonary hypertension (PH) patients, as well as, to shed light on the shape and strength of the dose-response association.

Methods

Studies published up to Jun 2021 in scientific databases such as Scopus, and PubMed as well as Google Scholar were searched. Cohort studies that reported risk estimates for at least two categories of BMI or per certain increase in BMI in relation to mortality in PH patients were included. Summary relative risks were determined with random effects models. Non-linear relationship was discovered with dose-response analysis.

Results

All in all, 15 cohort studies were selected. The number of participants was 127,215 out of which 73,999 were reported dead. The summary RR for mortality per a 5-unit increment in BMI was 0.83 (95% confidence interval 0.77–0.89; I² = 75.6%, n = 9) among PH patients. There was a non-linear dose-response relation between BMI and mortality in PH patients (P_{non−linearity} < 0.001), with the lowest risk being at BMI 32–38 kg/m².

Conclusion

Higher BMI is related to decreased risk of mortality among PH patients and the lowest point of the curve was seen at BMI 32–38.

Mortality in Pulmonary Arterial Hypertension in the Modern Era: Early Insights From the Pulmonary Hypertension Association Registry

Background Current mortality data for pulmonary arterial hypertension (PAH) in the United States are based on registries that enrolled patients prior to 2010. We sought to determine mortality in PAH in the modern era using the PHAR (Pulmonary Hypertension Association Registry). Methods and Results We identified all adult patients with PAH enrolled in the PHAR between September 2015 and September 2020 (N=935). We used Kaplan-Meier survival analysis and Cox proportional hazards models to assess mortality at 1, 2, and 3 years. Patients were stratified based on disease severity by 3 validated risk scores. In treatment-naïve patients, we compared survival based on initial treatment strategy. The median age was 56 years (44-68 years), and 76% were women. Of the 935 patients, 483 (52%) were ≤6 months from PAH diagnosis. There were 121 deaths (12.9%) during a median follow-up time of 489 days (281-812 days). The 1-, 2-, and 3-year mortality was 8% (95% CI, 6%-10%), 16% (95% CI, 13%-19%), and 21% (95% CI, 17%-25%), respectively. When stratified into low-, intermediate-, and high-risk PAH, the mortality at 1, 2, and 3 years was 1%, 4% to 6%, and 7% to 11% for low risk; 7% to 8%, 11% to 16%, and 18% to 20% for intermediate risk; and 12% to 19%, 22% to 38%, and 28% to 55% for high risk, respectively. In treatment-naïve patients, initial combination therapy was associated with better 1-year survival (adjusted hazard ratio, 0.43 [95% CI, 0.19-0.95]; P=0.037). Conclusions Mortality in the intermediate- and high-risk patients with PAH remains unacceptably high in the PHAR, suggesting the importance for early diagnosis, aggressive use of available therapies, and the need for better therapeutics.

Hispanic Ethnicity and Social Determinants of Health in Pulmonary Arterial Hypertension: The Pulmonary Hypertension Association Registry

Rationale There is a noticeable underrepresentation of minorities in clinical trials and registries in pulmonary arterial hypertension (PAH). Prior studies evaluating the association between Hispanic ethnicity and clinical outcomes in patients with PAH have not assessed the socioeconomic profile of Hispanic individuals or the significance of social determinants of health in clinical outcomes. Objective To determine the association between Hispanic ethnicity, social determinants of health, and clinical outcomes in PAH. Methods Prospective cohort study of adult participants with PAH enrolled in the Pulmonary Hypertension Association Registry, a multicenter US-based registry of patients treated at Pulmonary Hypertension Care Centers. Participants were classified as Hispanics and non-Hispanic Whites, based on self-reported ethnicity. A comparison of baseline clinical and sociodemographic characteristics between groups was performed as well using absolute standardized differences (ASD). The primary outcome of the study was to assess transplant-free survival between Hispanics and non-Hispanic Whites. A Cox proportional hazards model was used for the multivariable analysis after adjusting for age, sex, PAH etiology, annual income, education level and health insurance. Results A total of 683 individuals were included, 98 (14.3%) of Hispanic ethnicity. Hispanic patients had impaired access to health care (31.6% vs. 12.9% Medicaid/uninsured; ASD 0.35), lower education level (72.6% vs. 94.0% high school graduates or higher; ASD 0.60) and lower annual income (32.0% vs. 17.4% with income <20,000 US dollars; ASD 0.47), as compared with non-Hispanic Whites. Hispanic patients had a higher frequency of ER visits and a higher number of hospitalizations, despite having similar disease severity (incidence rate ratio 1.452, 95% CI 1.326 - 1.590 and 1.428, 95% CI 1.292 - 1.577, respectively). While the unadjusted analysis showed a lower transplant/death hazard ratio for Hispanics (HR 0.47, 95% CI 0.24-0.94; p=0.032), there was no association between Hispanic ethnicity and outcome in the multivariable model after adjusting for social determinants of health and other covariates (HR 0.76, 95% CI 0.35-1.62; p=0.474). Conclusions Hispanic ethnicity was not associated with differences in survival after adjusting for social determinants of health and other factors. Social determinants of health are important to consider when assessing the association between ethnicity and outcomes in PAH.

Impact of Pulmonary Arterial Hypertension on Systemic Inflammation, Cardiac Injury and Hemodynamics in Sepsis: A retrospective study from MIMIC-III

BACKGROUND

Sepsis and pulmonary arterial hypertension (PAH) may both present in a single patient in the intensive care unit. The impact of PAH on the sepsis process is not well understood. Here we assess the effect of PAH in patients with sepsis from multiple perspectives.

METHODS

Patients with sepsis with or without PAH underwent propensity score matching according to age, sex and ethnicity. Clinical complications, hemodynamics, and laboratory examinations, including heart injury and inflammation, were compared between the 2 groups. We aimed to model the relationship between the severity of PAH and systemic inflammation levels using linear regression analysis. Factors associated with 28-day and one-year mortality in patients with sepsis with PAH were also analyzed using binary logistic regression.

RESULTS

A total of 285 pairs of patients with sepsis with or without PAH were included in the analysis. There were no significant differences in the C-reactive protein (CRP), white blood cell (WBC), or lactate levels or neutrophil percentage between the 2 groups, and the mean pulmonary arterial pressure and N-terminal pro b-type natriuretic peptide (NTproBNP) level did not correlate with CRP, WBC or lactate. The cardiac injury indexes were significantly higher in the PAH group. Lower mean arterial pressure was found in patients with PAH. Longer ventilation duration was a risk factor for, while obesity was protective against, both short- and long-term mortality in patients with sepsis with PAH.

CONCLUSIONS

PAH had little effect on the inflammation profile in sepsis, but it may worsen the sepsis outcome by impairing cardiac function and subsequent hemodynamic stability.

What's new in pulmonary hypertension clinical research: lessons from the best abstracts at the 2020 American Thoracic Society International Conference

In this conference paper, we review the 2020 American Thoracic Society International Conference session titled, "What's New in Pulmonary Hypertension Clinical Research: Lessons from the Best Abstracts". This virtual mini-symposium took place on 21 October 2020, in lieu of the annual in-person ATS International Conference which was cancelled due to the COVID-19 pandemic. Seven clinical research abstracts were selected for presentation in the session, which encompassed five major themes: (1) standardizing diagnosis and management of pulmonary hypertension, (2) improving risk assessment in pulmonary arterial hypertension, (3) evaluating biomarkers of disease activity, (4) understanding metabolic dysregulation across the spectrum of pulmonary hypertension, and (5) advancing knowledge in chronic thromboembolic pulmonary hypertension. Focusing on these five thematic contexts, we review the current state of knowledge, summarize presented research abstracts, appraise their significance and limitations, and then discuss relevant future directions in pulmonary hypertension clinical research.