BMI Is Causally Associated With Pulmonary Artery Pressure But Not Hemodynamic Evidence of Pulmonary Vascular Remodeling

Emerging therapies: Potential roles of SGLT2 inhibitors in the management of pulmonary hypertension

Pulmonary hypertension (PH) is a pathophysiological disorder that may involve multiple clinical conditions and may be associated with a variety of cardiovascular and respiratory diseases. Pulmonary hypertension due to left heart disease (PH-LHD) currently lacks targeted therapies, while Pulmonary arterial hypertension (PAH), despite approved treatments, carries considerable residual risk. Metabolic dysfunction has been linked to the pathogenesis and prognosis of PH through various studies, with emerging metabolic agents offering a potential avenue for improving patient outcomes. Sodium-glucose cotransporter 2 inhibitor (SGLT-2i), a novel hypoglycemic agent, could ameliorate metabolic dysfunction and exert cardioprotective effects. Recent small-scale studies suggest SGLT-2i treatment may improve pulmonary artery pressure in patients with PH-LHD, and the PAH animal model shows that SGLT-2i can reduce pulmonary vascular remodeling and prevent progression in PAH, suggesting potential benefits for patients with PH-LHD and perhaps PAH. This review aims to succinctly review PH's pathophysiology, and the connection between metabolic dysfunction and PH, and investigate the prospective mechanisms of action of SGLT-2i in PH-LHD and PAH management.

Identification of Clinical Drivers of Left Atrial Enlargement Through Genomics of Left Atrial Size

BACKGROUND

Greater left atrial size is associated with a higher incidence of cardiovascular disease and mortality, but the full spectrum of diagnoses associated with left atrial enlargement in sex-stratified clinical populations is not well known. Our study sought to identify genetic risk mechanisms affecting left atrial diameter (LAD) in a clinical cohort.

METHODS

Using Vanderbilt deidentified electronic health record, we studied 6163 females and 5993 males of European ancestry who had at least 1 LAD measure and available genotyping. A sex-stratified polygenic score was constructed for LAD variation and tested for association against 1680 International Classification of Diseases code-based phenotypes. Two-sample univariable and multivariable Mendelian randomization approaches were used to assess etiologic relationships between candidate associations and LAD.

RESULTS

A phenome-wide association study identified 25 International Classification of Diseases code-based diagnoses in females and 11 in males associated with a polygenic score of LAD (false discovery rate q<0.01), 5 of which were further evaluated by Mendelian randomization (waist circumference [WC], atrial fibrillation, heart failure, systolic blood pressure, and coronary artery disease). Sex-stratified differences in the genetic associations between risk factors and a polygenic score for LAD were observed (WC for females; heart failure, systolic blood pressure, atrial fibrillation, and WC for males). By multivariable Mendelian randomization, higher WC remained significantly associated with larger LAD in females, whereas coronary artery disease, WC, and atrial fibrillation remained significantly associated with larger LAD in males.

CONCLUSIONS

In a clinical population, we identified, by genomic approaches, potential etiologic risk factors for larger LAD. Further studies are needed to confirm the extent to which these risk factors may be modified to prevent or reverse adverse left atrial remodeling and the extent to which sex modifies these risk factors.

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.

Genetics of Pulmonary Pressure and Right Ventricle Stress Identify Diabetes as a Causal Risk Factor

Background Epidemiologic studies have identified risk factors associated with pulmonary hypertension and right heart failure, but causative drivers of pulmonary hypertension and right heart adaptation are not well known. We sought to leverage unbiased genetic approaches to determine clinical conditions that share genetic architecture with pulmonary pressure and right ventricular dysfunction. Methods and Results We leveraged Vanderbilt University's deidentified electronic health records and DNA biobank to identify 14 861 subjects of European ancestry who underwent at least 1 echocardiogram with available estimates of pulmonary pressure and right ventricular function. Analyses of the study were performed between 2020 and 2022. The final analytical sample included 14 861 participants (mean [SD] age, 63 [15] years and mean [SD] body mass index, 29 [7] kg/m2). An unbiased phenome-wide association study identified diabetes as the most statistically significant clinical International Classifications of Diseases, Ninth Revision (ICD-9) code associated with polygenic risk for increased pulmonary pressure. We validated this finding further by finding significant associations between genetic risk for diabetes and a related condition, obesity, with pulmonary pressure estimate. We then used 2-sample univariable Mendelian randomization and multivariable Mendelian randomization to show that diabetes, but not obesity, was independently associated with genetic risk for increased pulmonary pressure and decreased right ventricle load stress. Conclusions Our findings show that genetic risk for diabetes is the only significant independent causative driver of genetic risk for increased pulmonary pressure and decreased right ventricle load stress. These findings suggest that therapies targeting genetic risk for diabetes may also potentially be beneficial in treating pulmonary hypertension and right heart dysfunction.

Clinical features do not identify risk of progression from isolated postcapillary pulmonary hypertension to combined pre- and postcapillary pulmonary hypertension

Pulmonary hypertension is a common sequelae of left heart failure and may present as isolated postcapillary pulmonary hypertension (Ipc-PH) or combined pre- and postcapillary pulmonary hypertension (Cpc-PH). Clinical features associated with progression from Ipc-PH to Cpc-PH have not yet been described. We extracted clinical data from patients who underwent right heart catheterizations (RHC) on two separate occasions. Ipc-PH was defined as mean pulmonary pressure >20 mmHg, pulmonary capillary wedge pressure >15 mmHg, and pulmonary vascular resistance (PVR) < 3 WU. Progression to Cpc-PH required an increase in PVR to ≥3 WU. We performed a retrospective cohort study with repeated assessments comparing subjects that progressed to Cpc-PH to subjects that remained with Ipc-PH. Of 153 patients with Ipc-PH at baseline who underwent a repeat RHC after a median of 0.7 years (IQR 0.2, 2.1), 33% (50/153) had developed Cpc-PH. In univariate analysis comparing the two groups at baseline, body mass index (BMI) and right atrial pressure were lower, while the prevalence of moderate or worse mitral regurgitation (MR) was higher among those who progressed. In age- and sex-adjusted multivariable analysis, only BMI (OR 0.94, 95% CI 0.90-0.99, p = 0.017, C = 0.655) and moderate or worse MR (OR 3.00, 95% CI 1.37-6.60, p = 0.006, C = 0.654) predicted progression, but with poor discriminatory power. This study suggests that clinical features alone cannot distinguish patients at risk for development of Cpc-PH and support the need for molecular and genetic studies to identify biomarkers of progression.

Association Between Body Mass Index and 30-Day Mortality in Patients with Pulmonary Hypertension Undergoing Non-cardiothoracic, Non-obstetric Surgery

INTRODUCTION

Evidence regarding the association between body mass index (BMI) and outcomes in non-cardiothoracic, non-obstetric surgery patients with pulmonary hypertension (PHTN) is limited. We aimed to investigate the association between BMI and 30-day mortality in non-cardiothoracic, non-obstetric surgery patients with pulmonary hypertension.

MATERIAL AND METHODS

We performed a secondary analysis of non-cardiothoracic, non-obstetric procedures on patients with PHTN between 2007 and 2013 at a single institution. Multivariable logistic regression models were used to estimate the association between BMI and 30-day mortality. Interaction and stratified analyses were conducted according to age, sex, PHTN medical therapy, anticipated inpatient or outpatient post-procedure status, procedure length > 2 h, open surgical approach, and PHTN severity class.

RESULTS

A total of 513 participants were included, with men accounting for 55.8% of the sample; the 30-day mortality was 1.9%. In the multivariate regression models, BMI was significantly associated with 30-day mortality after adjusting for potential covariates. A 1 kg/m² increase in BMI was associated with a 15% decrease in 30-day mortality (adjusted OR = 0.85, 95% CI: 0.73-0.98, P = 0.03). Stratified analyses indicated that this negative correlation was robust.

CONCLUSIONS

In this study, we found that low BMI is associated with increased risk of death in patients undergoing non-cardiothoracic, non-obstetric surgery requiring general anesthesia. Further studies are needed to confirm our findings.

Elucidating the Clinical Implications and Pathophysiology of Pulmonary Hypertension in Heart Failure With Preserved Ejection Fraction: A Call to Action: A Science Advisory From the American Heart Association

This science advisory focuses on the need to better understand the epidemiology, pathophysiology, and treatment of pulmonary hypertension in patients with heart failure with preserved ejection fraction. This clinical phenotype is important because it is common, is strongly associated with adverse outcomes, and lacks evidence-based therapies. Our goal is to clarify key knowledge gaps in pulmonary hypertension attributable to heart failure with preserved ejection fraction and to suggest specific, actionable scientific directions for addressing such gaps. Areas in need of additional investigation include refined disease definitions and interpretation of hemodynamics, as well as greater insights into noncardiac contributors to pulmonary hypertension risk, optimized animal models, and further molecular studies in patients with combined precapillary and postcapillary pulmonary hypertension. We highlight translational approaches that may provide important biological insight into pathophysiology and reveal new therapeutic targets. Last, we discuss the current and future landscape of potential therapies for patients with heart failure with preserved ejection fraction and pulmonary vascular dysfunction, including considerations of precision medicine, novel trial design, and device-based therapies, among other considerations. This science advisory provides a synthesis of important knowledge gaps, culminating in a collection of specific research priorities that we argue warrant investment from the scientific community.

Emerging therapies: The potential roles SGLT2 inhibitors, GLP1 agonists, and ARNI therapy for ARNI pulmonary hypertension

Pulmonary hypertension (PH) is a highly morbid condition. PH due to left heart disease (PH-LHD) has no specific therapies and pulmonary arterial hypertension (PAH) has substantial residual risk despite several approved therapies. Multiple lines of experimental evidence link metabolic dysfunction to the pathogenesis and outcomes in PH-LHD and PAH, and novel metabolic agents hold promise to improve outcomes in these populations. The antidiabetic sodium-glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide-1 (GLP1) agonists targeting metabolic dysfunction and improve outcomes in patients with LHD but have not been tested specifically in patients with PH. The angiotensin receptor/neprilysin inhibitors (ARNIs) produce significant improvements in cardiac hemodynamics and may improve metabolic dysfunction that could benefit the pulmonary circulation and right ventricle function. On the basis of promising preclinical work with these medications and clinical rationale, we explore the potential of SGLT2 inhibitors, GLP1 agonists, and ARNIs as therapies for both PH-LHD and PAH.

Risk factors associated with pulmonary hypertension in obesity hypoventilation syndrome

STUDY OBJECTIVES

Pulmonary hypertension (PH) is prevalent in obesity hypoventilation syndrome (OHS). However, there is a paucity of data assessing pathogenic factors associated with PH. Our objective is to assess risk factors that may be involved in the pathogenesis of PH in untreated OHS.

METHODS

In a post-hoc analysis of the Pickwick trial, we performed a bivariate analysis of baseline characteristics between patients with and without PH. Variables with a p value ≤0.10 were defined as potential risk factors and were grouped by theoretical pathogenic mechanisms in several adjusted models. Similar analysis was carried out for the two OHS phenotypes, with and without severe concomitant obstructive sleep apnea (OSA).

RESULTS

Of 246 patients with OHS, 122 (50%) had echocardiographic evidence of PH defined as systolic pulmonary artery pressure ≥40 mmHg. Lower levels of awake PaO₂ and higher body mass index (BMI) were independent risk factors in the multivariate model, with a negative and positive adjusted linear association, respectively (adjusted odds ratio 0.96; 95% CI 0.93 to 0.98; p = 0.003 for PaO₂, and 1.07; 95% CI 1.03 to 1.12; p = 0.001 for BMI). In separate analyses, BMI and PaO₂ were independent risk factors in the severe OSA phenotype, whereas BMI and peak in-flow velocity in early (E)/late diastole (A) ratio were independent risk factors in the non-severe OSA phenotype.

CONCLUSIONS

This study identifies obesity per se as a major independent risk factor for PH, regardless of OHS phenotype. Therapeutic interventions targeting weight loss may play a critical role in improving PH in this patient population.

CLINICAL TRIALS REGISTRATION

Registry: Clinicaltrial.gov; Identifier: NCT01405976.

Metabolics of PH - an update

PURPOSE OF REVIEW

While there has been a longstanding interest in metabolic disease in pulmonary hypertension, publications in the last several years have translated basic science findings to human disease and even led to recently published studies of metabolic therapy in pulmonary arterial hypertension that are discussed here.

RECENT FINDINGS

Progress has been made in four key areas including mechanisms of insulin resistance in pulmonary arterial hypertension, the role of obesity in pulmonary vascular disease, novel clinical trials targeting metabolism in pulmonary hypertension, and the role of metabolism in chronic thromboembolic pulmonary hypertension.

SUMMARY

: Insulin resistance in pulmonary arterial hypertension is primarily in the lipid axis. There are systemic manifestations of insulin resistance including right ventricular lipotoxicity. Obesity is associated with elevation of right ventricular systolic pressure even in a healthy population and therapies in pulmonary arterial hypertension that target metabolism hold promise for improving exercise, right ventricular function, and visceral adiposity. Finally, there are emerging data that chronic thromboembolic pulmonary hypertension is similarly characterized by metabolic alterations, though the specific metabolites may be different from pulmonary arterial hypertension.