Pulmonary hypertension-targeted therapies in heart failure: A systematic review and meta-analysis

Managing Pulmonary Arterial Hypertension With Cardiopulmonary Comorbidities

Pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with left-sided heart and lung diseases are most commonly easily discriminated and treated accordingly. With the changing epidemiology of PAH, however, a growing proportion of patients at the time of diagnosis present with comorbidities of varying severity. In addition to classical PAH, two distinct phenotypes have emerged: a heart failure with preserved ejection fraction-like phenotype and a lung phenotype. Importantly, the evidence supporting the currently proposed treatment algorithm for PAH has been generated mainly from PAH trials in which patients with cardiopulmonary comorbidities have been underrepresented or excluded. As a consequence, the best therapeutic approach for patients with common PAH with cardiopulmonary comorbidities remains largely unknown and requires further investigation. The present article reviews the relevant literature on the topic and describes the authors' views on the current therapeutic approach for these patients.

Paradoxical Worsening of Pulmonary Hypertension Following Closure of Arteriovenous Fistula: A Case Report and Literature Review

This case report presents the atypical instance of a 59-year-old female patient with end-stage renal disease (ESRD) who was initially referred to the pulmonary clinic for evaluation due to a low diffusing capacity of the lung for carbon monoxide (DLCO). Pulmonary hypertension (PH) was suspected, and a subsequent right heart catheterization (RHC) confirmed PH attributed to group 5 PH, leading to the decision to close the unused arteriovenous fistula (AVF) to manage PH. Unexpectedly, a follow-up RHC showed a worsening of PH with elevated pulmonary capillary wedge pressure (PCWP), revealing an additional component of post-capillary group 2 PH. This case emphasizes the significance of recognizing a low DLCO as a potential trigger for PH assessment, especially in patients with comorbidities like ESRD. Furthermore, it highlights the unusual yet critical occurrence of PH exacerbation following AVF closure.

Cardiac Effects of Phosphodiesterase-5 Inhibitors: Efficacy and Safety

The coexistence of cardiovascular disease and erectile dysfunction is widespread, possibly owing to underlying endothelial dysfunction in both diseases. Millions of patients with cardiovascular disease are prescribed phosphodiesterase-5 (PDE5) inhibitors for the management of erectile dysfunction. Although the role of PDE5 inhibitors in erectile dysfunction therapy is well established, their effects on the cardiovascular system are unclear. Preclinical studies investigating the effect of PDE5 inhibitors on ischemia-reperfusion injury, pressure overload-induced hypertrophy, and chemotoxicity suggested a possible clinical role for each of these medications; however, attempts to translate these findings to the bedside have resulted in mixed outcomes. In this review, we explore the biologic preclinical effects of PDE5 inhibitors in mediating cardioprotection. We then examine clinical trials investigating PDE5 inhibition in patients with heart failure, coronary artery disease, and ventricular arrhythmias and discuss why the studies likely have yet to show positive results and efficacy with PDE5 inhibition despite no safety concerns.

Pulmonary Hypertension Association's 2022 International Conference Scientific Sessions Overview

The considerable progress made in recent years in the diagnosis, risk stratification, and treatment of pulmonary hypertension was highlighted during the most recent edition of the Pulmonary Hypertension Association Scientific Sessions, which was held in Atlanta, Georgia from June 9 to 11, 2022, with the theme: Vision for the PHuture: The Evolving Science and Management of PH. Content presented over the 3-day conference focused on scientific and management updates since the last sessions were held in 2018 and included didactic talks, debates, and roundtable discussions across a broad spectrum of topics related to pulmonary hypertension. This article aims to summarize the key messages from each of the session talks.

The thromboxane receptor antagonist NTP42 promotes beneficial adaptation and preserves cardiac function in experimental models of right heart overload

Background

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by increased pulmonary artery pressure leading to right ventricular (RV) failure. While current PAH therapies improve patient outlook, they show limited benefit in attenuating RV dysfunction. Recent investigations demonstrated that the thromboxane (TX) A₂ receptor (TP) antagonist NTP42 attenuates experimental PAH across key hemodynamic parameters in the lungs and heart. This study aimed to validate the efficacy of NTP42:KVA4, a novel oral formulation of NTP42 in clinical development, in preclinical models of PAH while also, critically, investigating its direct effects on RV dysfunction.

Methods

The effects of NTP42:KVA4 were evaluated in the monocrotaline (MCT) and pulmonary artery banding (PAB) models of PAH and RV dysfunction, respectively, and when compared with leading standard-of-care (SOC) PAH drugs. In addition, the expression of the TP, the target for NTP42, was investigated in cardiac tissue from several other related disease models, and from subjects with PAH and dilated cardiomyopathy (DCM).

Results

In the MCT-PAH model, NTP42:KVA4 alleviated disease-induced changes in cardiopulmonary hemodynamics, pulmonary vascular remodeling, inflammation, and fibrosis, to a similar or greater extent than the PAH SOCs tested. In the PAB model, NTP42:KVA4 improved RV geometries and contractility, normalized RV stiffness, and significantly increased RV ejection fraction. In both models, NTP42:KVA4 promoted beneficial RV adaptation, decreasing cellular hypertrophy, and increasing vascularization. Notably, elevated expression of the TP target was observed both in RV tissue from these and related disease models, and in clinical RV specimens of PAH and DCM.

Conclusion

This study shows that, through antagonism of TP signaling, NTP42:KVA4 attenuates experimental PAH pathophysiology, not only alleviating pulmonary pathologies but also reducing RV remodeling, promoting beneficial hypertrophy, and improving cardiac function. The findings suggest a direct cardioprotective effect for NTP42:KVA4, and its potential to be a disease-modifying therapy in PAH and other cardiac conditions.

Therapeutic Challenges and Emerging Treatment Targets for Pulmonary Hypertension in Left Heart Disease

Pulmonary hypertension (PH) attributable to left heart disease (LHD) is believed to be the most common form of PH and is strongly associated with increased mortality and morbidity in this patient population. Specific therapies for PH‐LHD have not yet been identified and the use of pulmonary artery hypertension‐targeted therapies in PH‐LHD are not recommended. Endothelin receptor antagonists, phosphodiesterase‐5 inhibitors, guanylate cyclase stimulators, and prostacyclins have all been studied in PH‐LHD with conflicting results. Understanding the mechanisms underlying PH‐LHD could potentially provide novel therapeutic targets. Fibrosis, oxidative stress, and metabolic syndrome have been proposed as pathophysiological components of PH‐LHD. Genetic associations have also been identified, offering additional mechanisms with biological plausibility. This review summarizes the evidence and challenges for treatment of PH‐LHD and focuses on underlying mechanisms on the horizon that could develop into potential therapeutic targets for this disease.

Pulmonary Hypertension Complicating Pregnancy

Purpose of review

This study aims to describe the pathophysiology of pregnancy in pulmonary hypertension (PH) and review recent literature on maternal and fetal outcomes.

Recent findings

There is an increasing number of pregnant women with PH. Maternal mortality in pulmonary arterial hypertension (PAH) ranges from 9 to 25%, most commonly from heart failure and arrythmias. The highest risk of death is peri-partum and post-partum. Fetal/neonatal morbidity and mortality are also substantial. There are high rates of prematurity, intrauterine growth retardation, and preeclampsia. Women should be referred to expert centers for management. Combination PAH therapy with parenteral prostacyclin and a phosphodiesterase type V inhibitor is recommended. Induced vaginal delivery is preferred, except in cases of severe heart failure or obstetric indications for cesarean section.

Summary

Despite advances in management, pregnancy in PAH remains a high-risk condition and should be prevented.

Targeted therapy with phosphodiesterase 5 inhibitors in patients with pulmonary hypertension due to heart failure and elevated pulmonary vascular resistance: a systematic review

Pulmonary Hypertension due to left heart disease is the most common type of Pulmonary Hypertension. Morbidity and mortality significantly increase once Pulmonary Hypertension is present. Treatment is aimed toward optimizing the underlying condition. Targeted therapy has been evaluated in small studies with mixed results. The goal of this systematic review is to identify the possible benefit and safety of Phosphodiesterase 5 inhibitors in Pulmonary Hypertension due to left heart disease with elevated pulmonary vascular resistance, diagnosed by right heart catheterization. Electronic searches using MEDLINE/PREMEDLINE, EMBASE, and The Cochrane Library were searched on 21 October 2018. Randomized clinical trials comparing Phosphodiesterase 5 inhibitors versus placebo in patients with proven Pulmonary Hypertension by right heart catheterization secondary to left heart disease (both heart failure with reduced ejection fraction and with preserved ejection fraction) and reported pulmonary vascular resistance were included. We identified 436 potentially relevant studies. After reviewing the titles and abstracts to exclude irrelevant articles, five randomized clinical trials were considered for the study. Sildenafil was well tolerated among all studies. Sildenafil was found to improve hemodynamics, exercise capacity, and quality of life in patients with elevated pulmonary vascular resistance. Phosphodiesterase 5 inhibitors therapy in patients with proven Pulmonary Hypertension due to left heart disease and elevated pulmonary vascular resistance by right heart catheterization may improve the quality of life, exercise capacity, and pulmonary hemodynamics. Further prospective randomized controlled studies are needed to confirm.

Repurposing of medications for pulmonary arterial hypertension

This manuscript on drug repurposing incorporates the broad experience of members of the Pulmonary Vascular Research Institute's Innovative Drug Development Initiative as an open debate platform for academia, the pharmaceutical industry and regulatory experts surrounding the future design of clinical trials in pulmonary hypertension. Drug repurposing, use of a drug in a disease for which it was not originally developed, in pulmonary arterial hypertension has been a remarkable success story, as highlighted by positive large phase 3 clinical trials using epoprostenol, bosentan, iloprost, and sildenafil. Despite the availability of multiple therapies for pulmonary arterial hypertension, mortality rates have modestly changed. Moreover, pulmonary arterial hypertension patients are highly symptomatic and frequently end up on parental therapy and lung transplant waiting lists. Therefore, an unmet need for new treatments exists and drug repurposing may be an important avenue to address this problem.

The evolving role of interventional cardiology in the treatment of pulmonary hypertension

Pulmonary hypertension (PH) is a heterogeneous group of diseases defined by a mean pulmonary arterial pressure greater than 20 mmHg. Clinically, PH is classified into five groups and the group of PH generally defines the cause of PH and the therapeutic options. Currently, medical therapies that target the prostacyclin, endothelin, and nitric oxide pathways are used in pulmonary arterial hypertension and chronic thromboembolic PH (CTEPH) patients. Moreover, surgery can improve outcomes in PH as pulmonary thromboendarterectomy can be curative for CTEPH and lung transplantation is used for end-stage PH. Despite these diverse treatment options, PH patients continue to have high symptom burden and poor long-term outcomes. However, advances in percutaneous technology are opening new avenues for the management of PH. In this review, we discuss the available data supporting the use of four interventional procedures: balloon atrial septostomy, transcatheter Potts shunt, balloon pulmonary angioplasty, and pulmonary artery denervation for the treatment of PH. These procedures provide hemodynamic and functional improvements in PH patients, but they come with their own unique risk profiles. Hopefully, these procedures will continue to be refined and thereby provide a venue for interventional cardiology to safely and effectively improve outcomes for PH moving forward.

Pulmonary Hypertension Due to Left Heart Disease

Pulmonary hypertension (PH) due to left heart disease (LHD) is the most common type of PH and is defined as mean pulmonary artery systolic pressure of >20 mm Hg and pulmonary capillary wedge pressure >15 mm Hg during right heart catheterization. LHD may lead to elevated left atrial pressure alone, which in the absence of intrinsic pulmonary vascular disease will result in PH without changes in pulmonary vascular resistance. Persistent elevation in left atrial pressure may, however, also be associated with subsequent pulmonary vascular remodeling, vasoconstriction, and an increase in pulmonary vascular resistance. Hence, there are 2 subgroups of PH due to LHD, isolated postcapillary PH and combined post- and precapillary PH, with these groups have differing clinical implications. Differentiation of pulmonary arterial hypertension and PH due to LHD is critical to guide management planning; however, this may be challenging. Older patients, patients with metabolic syndrome, and patients with imaging and clinical features consistent with left ventricular dysfunction are suggestive of LHD etiology rather than pulmonary arterial hypertension. Hemodynamic measures such as diastolic pressure gradient, transpulmonary gradient, and pulmonary vascular resistance may assist to differentiate pre- from postcapillary PH and offer prognostic insights. However, these are influenced by fluid status and heart failure treatment. Pulmonary arterial hypertension therapies have been trialed in the treatment with concerning results reflecting disease heterogeneity, variation in inclusion criteria, and mixed end point criteria. The aim of this review is to provide an updated definition, discuss possible pathophysiology, clinical aspects, and the available treatment options for PH due to LHD.