Renin-Angiotensin-Aldosterone System Inhibitor Use and Mortality in Pulmonary Hypertension: Insights From the Veterans Affairs Clinical Assessment Reporting and Tracking Database

Pulmonary hypertension associated to left heart disease: Phenotypes and treatment

Pulmonary hypertension associated to left heart disease (PH-LHD) refers to a clinical and haemodynamic condition of pulmonary hypertension associated with a heterogeneous group of diseases affecting any of the compartments that form the left ventricle and left atrium. PH-LHD is the most common cause of PH, accounting for 65-80 % of diagnoses. Based on the haemodynamic phase of the disease, PH-LDH is classified into three subgroups: postcapillary PH, isolated postcapillary PH and combined pre-postcapillary PH (CpcPH). Several signaling pathways involved in the regulation of vascular tone are dysfunctional in PH-LHD, including nitric oxide, MAP kinase and endothelin-1 pathways. These pathways are the same as those altered in PH group 1, however PH-LHD can heardly be treated by specific drugs that act on the pulmonary circulation. In this manuscript we provide a state of the art of the available clinical trials investigating the safety and efficacy of PAH-specific drugs, as well as drugs active in patients with heart failure and PH-LHD. We also discuss the different phenotypes of PH-LHD, as well as molecular targets and signaling pathways potentially involved in the pathophysiology of the disease. Finally we will mention some new emerging therapies that can be used to treat this form of PH.

Nephrectomy and high-salt diet inducing pulmonary hypertension and kidney damage by increasing Ang II concentration in rats

BACKGROUND

Chronic kidney disease (CKD) is a significant risk factor for pulmonary hypertension (PH), a complication that adversely affects patient prognosis. However, the mechanisms underlying this association remain poorly understood. A major obstacle to progress in this field is the lack of a reliable animal model replicating CKD-PH.

METHODS

This study aimed to establish a stable rat model of CKD-PH. We employed a combined approach, inducing CKD through a 5/6 nephrectomy and concurrently exposing the rats to a high-salt diet. The model's hemodynamics were evaluated dynamically, alongside a comprehensive assessment of pathological changes in multiple organs. Lung tissues and serum samples were collected from the CKD-PH rats to analyze the expression of angiotensin-converting enzyme 2 (ACE2), evaluate the activity of key vascular components within the renin-angiotensin-aldosterone system (RAAS), and characterize alterations in the serum metabolic profile.

RESULTS

At 14 weeks post-surgery, the CKD-PH rats displayed significant changes in hemodynamic parameters indicative of pulmonary arterial hypertension. Additionally, right ventricular hypertrophy was observed. Notably, no evidence of pulmonary vascular remodeling was found. Further analysis revealed RAAS dysregulation and downregulated ACE2 expression within the pulmonary vascular endothelium of CKD-PH rats. Moreover, the serum metabolic profile of these animals differed markedly from the sham surgery group.

CONCLUSIONS

Our findings suggest that the development of pulmonary arterial hypertension in CKD-PH rats is likely a consequence of a combined effect: RAAS dysregulation, decreased ACE2 expression in pulmonary vascular endothelial cells, and metabolic disturbances.

Management of Pulmonary Hypertension in the Context of Heart Failure with Preserved Ejection Fraction

PURPOSE OF REVIEW

To review the current evidence and modalities for treating pulmonary hypertension (PH) in heart failure with preserved ejection fraction (HFpEF).

RECENT FINDINGS

In recent years, several therapies have been developed that improve morbidity in HFpEF, though these studies have not specifically studied patients with PF-HFpEF. Multiple trials of therapies specifically targeting the pulmonary vasculature such as phosphodiesterase (PDE) inhibitors, prostacyclin analogs, endothelin receptor antagonists (ERA), and soluble guanylate cyclase stimulators have also been conducted. However, these therapies demonstrated lack of consistency in improving hemodynamics or functional outcomes in PH-HFpEF. There is limited evidence to support the use of pulmonary vasculature-targeting therapies in PH-HFpEF. The mainstay of therapy remains the treatment of the underlying HFpEF condition. There is emerging evidence that newer HF therapies such as sodium-glucose transporter 2 inhibitors and angiotensin-receptor-neprilysin inhibitors are associated with improved hemodynamics and quality of life of patients with PH-HFpEF. There is also a growing realization that more robust phenotyping PH and right ventricular (RV) function may hold promise for therapeutic strategies for patients with PH-HFpEF.

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.

Therapeutic targeting of mineralocorticoid receptors in pulmonary hypertension: Insights from basic research

Pulmonary hypertension (PH) is characterized by pulmonary vascular remodeling and associated with adverse outcomes. In patients with PH, plasma aldosterone levels are elevated, suggesting that aldosterone and its receptor, the mineralocorticoid receptor (MR), play an important role in the pathophysiology of PH. The MR plays a crucial role in adverse cardiac remodeling in left heart failure. A series of experimental studies from the past few years indicate that MR activation promotes adverse cellular processes that lead to pulmonary vascular remodeling, including endothelial cell apoptosis, smooth muscle cell (SMC) proliferation, pulmonary vascular fibrosis, and inflammation. Accordingly, in vivo studies have demonstrated that pharmacological inhibition or cell-specific deletion of the MR can prevent disease progression and partially reverse established PH phenotypes. In this review, we summarize recent advances in MR signaling in pulmonary vascular remodeling based on preclinical research and discuss the potential, but also the challenges, in bringing MR antagonists (MRAs) into clinical application.

Potential long-term effects of SARS-CoV-2 infection on the pulmonary vasculature: Multilayered cross-talks in the setting of coinfections and comorbidities

The Coronavirus Disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and its sublineages pose a new challenge to healthcare systems worldwide due to its ability to efficiently spread in immunized populations and its resistance to currently available therapies. COVID-19, although targeting primarily the respiratory system, is also now well established that later affects every organ in the body. Most importantly, despite the available therapy and vaccine-elicited protection, the long-term consequences of viral infection in breakthrough and asymptomatic individuals are areas of concern. In the past two years, investigators accumulated evidence on how the virus triggers our immune system and the molecular signals involved in the cross-talk between immune cells and structural cells in the pulmonary vasculature to drive pathological lung complications such as endothelial dysfunction and thrombosis. In the review, we emphasize recent updates on the pathophysiological inflammatory and immune responses associated with SARS-CoV-2 infection and their potential long-term consequences that may consequently lead to the development of pulmonary vascular diseases.

Emerging vascular cell-specific roles for mineralocorticoid receptor: implications for understanding sex differences in cardiovascular disease

As growing evidence implicates extrarenal mineralocorticoid receptor (MR) in cardiovascular disease (CVD), recent studies have defined both cell- and sex-specific roles. MR is expressed in vascular smooth muscle (SMC) and endothelial cells (ECs). This review integrates published data from the past 5 years to identify novel roles for vascular MR in CVD, with a focus on understanding sex differences. Four areas are reviewed in which there is recently expanded understanding of the cell type- or sex-specific role of MR in 1) obesity-induced microvascular endothelial dysfunction, 2) vascular inflammation in atherosclerosis, 3) pulmonary hypertension, and 4) chronic kidney disease (CKD)-related CVD. The review focuses on preclinical data on each topic describing new mechanistic paradigms, cell type-specific mechanisms, sexual dimorphism if addressed, and clinical implications are then considered. New data support that MR drives vascular dysfunction induced by cardiovascular risk factors via sexually dimorphic mechanisms. In females, EC-MR contributes to obesity-induced endothelial dysfunction by regulating epithelial sodium channel expression and by inhibiting estrogen-induced nitric oxide production. In males with hyperlipidemia, EC-MR promotes large vessel inflammation by genomic regulation of leukocyte adhesion molecules, which is inhibited by the estrogen receptor. In pulmonary hypertension models, MRs in EC and SMC contribute to distinct components of disease pathologies including pulmonary vessel remodeling and RV dysfunction. Despite a female predominance in pulmonary hypertension, sex-specific roles for MR have not been explored. Vascular MR has also been directly implicated in CKD-related vascular dysfunction, independent of blood pressure. Despite these advances, sex differences in MR function remain understudied.

An algorithm to identify cases of pulmonary arterial hypertension from the electronic medical record

BACKGROUND

Study of pulmonary arterial hypertension (PAH) in claims-based (CB) cohorts may facilitate understanding of disease epidemiology, however previous CB algorithms to identify PAH have had limited test characteristics. We hypothesized that machine learning algorithms (MLA) could accurately identify PAH in an CB cohort.

METHODS

ICD-9/10 codes, CPT codes or PAH medications were used to screen an electronic medical record (EMR) for possible PAH. A subset (Development Cohort) was manually reviewed and adjudicated as PAH or "not PAH" and used to train and test MLAs. A second subset (Refinement Cohort) was manually reviewed and combined with the Development Cohort to make The Final Cohort, again divided into training and testing sets, with MLA characteristics defined on test set. The MLA was validated using an independent EMR cohort.

RESULTS

194 PAH and 786 "not PAH" in the Development Cohort trained and tested the initial MLA. In the Final Cohort test set, the final MLA sensitivity was 0.88, specificity was 0.93, positive predictive value was 0.89, and negative predictive value was 0.92. Persistence and strength of PAH medication use and CPT code for right heart catheterization were principal MLA features. Applying the MLA to the EMR cohort using a split cohort internal validation approach, we found 265 additional non-confirmed cases of suspected PAH that exhibited typical PAH demographics, comorbidities, hemodynamics.

CONCLUSIONS

We developed and validated a MLA using only CB features that identified PAH in the EMR with strong test characteristics. When deployed across an entire EMR, the MLA identified cases with known features of PAH.

Pulmonary Hypertension in the Context of Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is the most common form of heart failure and frequently is associated with pulmonary hypertension (PH). HFpEF associated with PH may be difficult to distinguish from precapillary forms of PH, although this distinction is crucial because therapeutic pathways are divergent for the two conditions. A comprehensive and systematic approach using history, clinical examination, and noninvasive and invasive evaluation with and without provocative testing may be necessary for accurate diagnosis and phenotyping. After diagnosis, HFpEF associated with PH can be subdivided into isolated postcapillary pulmonary hypertension (IpcPH) and combined postcapillary and precapillary pulmonary hypertension (CpcPH) based on the presence or absence of elevated pulmonary vascular resistance. CpcPH portends a worse prognosis than IpcPH. Despite its association with reduced functional capacity and quality of life, heart failure hospitalizations, and higher mortality, therapeutic options focused on PH for HFpEF associated with PH remain limited. In this review, we aim to provide an updated overview on clinical definitions and hemodynamically characterized phenotypes of PH, pathophysiologic features, therapeutic strategies, and ongoing challenges in this patient population.

Effect of spironolactone use in pulmonary arterial hypertension - analysis from pivotal trial databases

Spironolactone, a common diuretic used in the treatment of pulmonary arterial hypertension (PAH), improves cardiopulmonary hemodynamics by attenuating the adverse effects of hyperaldosteronism on endothelin type-B receptor function within pulmonary endothelial cells. Spironolactone has demonstrated vascular remodeling properties and reduced all-cause mortality in patients with severe heart failure. Despite widespread use, however, its effect on morbidity and mortality in PAH has not been fully explored. A large cohort of PAH patients from a harmonized dataset from four pivotal trials were analyzed to characterize the patient population and outcomes associated with spironolactone treatment. Of 1229 evaluable patients, 74% were female, mean age of 47 ± 15 years, baseline six-minute walk distance (6MWD) 345 ± 74 m and 75% were World health Organization (WHO) functional class (FC) III/IV. Of the patients receiving spironolactone, 43% were on subcutaneous treprostinil, compared to 29.9% of those patients who were not receiving spironolactone. Long-term spironolactone-treated PAH patients were older (p = 0.01), had lower baseline 6MWD (p = 0.01) and cardiac index (p < 0.01), higher baseline Borg dyspnea score (p = 0.01), WHO functional class, and right arterial pressure (p < 0.01). Additionally, spironolactone-treated patients tended to have higher hazard of clinical worsening (p < 0.01). A propensity analysis was performed and when controlled for disease severity, revealed that spironolactone-treated patients did not demonstrate improved outcomes in terms of survival and clinical worsening. Across studies, the current analysis has demonstrated that the actions of spironolactone within the context of the PAH disease process may differ from its action in CHF patients. Despite reported outcomes of spironolactone use in patients with left heart disease, these findings may not translate to right heart failure and pulmonary vascular pathology, as similar outcomes have not necessarily been recognized in the PAH patient population. Future studies are needed to explore these findings further.

Mineralocorticoid receptors in pulmonary hypertension and right heart failure: From molecular biology to therapeutic targeting

Pulmonary hypertension (PH) is a devastating condition characterized by pulmonary vascular remodelling, leading to progressive increase in pulmonary artery pressure and subsequent right ventricular failure. Aldosterone and the mineralocorticoid receptor (MR), a nuclear transcription factor, are key drivers of cardiovascular disease and MR antagonists are well-established in heart failure. Now, a growing body of evidence points at a detrimental role of MR in PH. Pharmacological MR blockade attenuated PH and prevented RV failure in experimental models. Mouse models with cell selective MR deletion suggest that this effect is mediated by MR in endothelial cells. While the evidence from experimental studies appears convincing, the available clinical data on MR antagonist use in patients with PH is more controversial. Integrated analysis of clinical data together with MR-dependent molecular alterations may provide insights why some patients respond to MRA treatment while others do not. Potential ways to identify MRA 'responders' include the analysis of underlying PH causes, stage of disease, or sex, as well as new biomarkers.

Angiotensin II type 1 receptor mediates pulmonary hypertension and right ventricular remodeling induced by inhaled nicotine

Use of electronic cigarettes is rapidly increasing among youth and young adults, but little is known regarding the long-term cardiopulmonary health impacts of these nicotine-containing devices. Our group has previously demonstrated that chronic, inhaled nicotine induces pulmonary hypertension (PH) and right ventricular (RV) remodeling in mice. These changes were associated with upregulated RV angiotensin-converting enzyme (ACE). Angiotensin II receptor blockers (ARBs) have been shown to reverse cigarette smoking-induced PH in rats. ACE inhibitor and ARB use in a large retrospective cohort of patients with PH is associated with improved survival. Here, we utilized losartan (an ARB specific for angiotensin II type 1 receptor) to further explore nicotine-induced PH. Male C57BL/6 mice received nicotine vapor for 12 h/day, and exposure was assessed using serum cotinine to achieve levels comparable to human smokers or electronic cigarette users. Mice were exposed to nicotine for 8 wk and a subset was treated with losartan via an osmotic minipump. Cardiac function was assessed using echocardiography and catheterization. Although nicotine exposure increased angiotensin II in the RV and lung, this finding was nonsignificant. Chronic, inhaled nicotine significantly increased RV systolic pressure and RV free wall thickness versus air control. These parameters were significantly lower in mice receiving both nicotine and losartan. Nicotine significantly increased RV internal diameter, with no differences seen between the nicotine and nicotine-losartan group. Neither nicotine nor losartan affected left ventricular structure or function. These findings provide the first evidence that antagonism of the angiotensin II type 1 receptor can ameliorate chronic, inhaled nicotine-induced PH and RV remodeling.NEW & NOTEWORTHY Chronic, inhaled nicotine causes pulmonary hypertension and right ventricular remodeling in mice. Treatment with losartan, an angiotensin II type 1 receptor antagonist, ameliorates nicotine-induced pulmonary hypertension and right ventricular remodeling. This novel finding provides preclinical evidence for the use of renin-angiotensin system-based therapies in the treatment of pulmonary hypertension, particularly in patients with a history of tobacco-product use.