Pulmonary arterial hypertension: tailoring treatment to risk in the current era

Efficacy of oral treprostinil for treating pulmonary arterial hypertension: a systematic review and meta-analysis

Introduction

Pulmonary arterial hypertension (PAH) is a progressive condition characterized by elevated blood pressure in the pulmonary arteries, leading to significant morbidity and mortality. Treprostinil, a synthetic analogue of prostacyclin, has emerged as a potential treatment option.

Aim

The efficacy and safety of oral treprostinil in PAH patients remain subjects of ongoing research.

Methods

Comprehensive literature searches were performed across multiple databases for studies assessing the efficacy and/or safety of treprostinil in PAH patients. Quality assessment and statistical analysis were performed using the Cochrane Collaboration's tool and Comprehensive Meta-Analysis software, respectively.

Results

From 680 records identified, four studies met the inclusion criteria. These studies demonstrated that oral treprostinil significantly improved exercise capacity as measured by the 6-minute walk distance (6MWD), with a mean difference of 13.13 m in favor of treprostinil, despite high heterogeneity. The analysis also showed an increased risk of adverse events leading to discontinuation in the treprostinil group (OR = 4.39) but a protective effect against clinical worsening (OR = 0.554). No significant impact on mortality was observed.

Conclusions

Oral treprostinil offers a significant benefit in improving exercise capacity in PAH patients, with a potential role in delaying clinical worsening. However, the increased risk of adverse events necessitates careful patient management. These findings support the inclusion of oral treprostinil in the treatment strategy for PAH, underscoring the need for further research to optimize its use and understand its long-term impact on patient outcomes.Level of evidence: I.

Pulmonary hypertension

Pulmonary hypertension encompasses a range of conditions directly or indirectly leading to elevated pressures within the pulmonary arteries. Five main groups of pulmonary hypertension are recognized, all defined by a mean pulmonary artery pressure of >20 mmHg: pulmonary arterial hypertension (rare), pulmonary hypertension associated with left-sided heart disease (very common), pulmonary hypertension associated with lung disease (common), pulmonary hypertension associated with pulmonary artery obstructions, usually related to thromboembolic disease (rare), and pulmonary hypertension with unclear and/or multifactorial mechanisms (rare). At least 1% of the world's population is affected, with a greater burden more likely in low-income and middle-income countries. Across all its forms, pulmonary hypertension is associated with adverse vascular remodelling with obstruction, stiffening and vasoconstriction of the pulmonary vasculature. Without proactive management this leads to hypertrophy and ultimately failure of the right ventricle, the main cause of death. In older individuals, dyspnoea is the most common symptom. Stepwise investigation precedes definitive diagnosis with right heart catheterization. Medical and surgical treatments are approved for pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. There are emerging treatments for other forms of pulmonary hypertension; but current therapy primarily targets the underlying cause. There are still major gaps in basic, clinical and translational knowledge; thus, further research, with a focus on vulnerable populations, is needed to better characterize, detect and effectively treat all forms of pulmonary hypertension.

Plasma Connective Tissue Growth Factor as a Biomarker of Pulmonary Arterial Hypertension Associated With Congenital Heart Disease in Adults

BACKGROUND

Connective tissue growth factor (CTGF) has diagnostic value for pulmonary arterial hypertension (PAH) associated with congenital heart disease (CHD) in children; however, its value in adult patients remains unclear. This study evaluated CTGF as a biomarker in adult PAH-CHD patients.

METHODS AND RESULTS

Based on mean pulmonary artery pressure (mPAP), 56 CHD patients were divided into 3 groups: without PAH (W; mPAP <25 mmHg; n=28); mild PAH (M; mPAP 25-35 mmHg; n=18); and moderate and severe PAH (H; mPAP ≥35 mmHg; n=10). The control group consisted of 28 healthy adults. Plasma CTGF and B-type natriuretic peptide (BNP) concentrations were determined. Plasma CTGF concentrations were higher in the H and M groups than in the W and control groups, and were higher in the H than M group. Plasma CTGF concentrations were positively correlated with pulmonary artery systolic pressure (PASP), mPAP, and pulmonary vascular resistance, and negatively correlated with mixed venous oxygen saturation. CTGF, BNP, red blood cell distribution width, and World Health Organization Class III/IV were risk factors for PAH in CHD patients, and CTGF was an independent risk factor for PAH-CHD. The efficacy of CTGF in the diagnosis of PAH was not inferior to that of BNP.

CONCLUSIONS

CTGF is a biomarker of PAH associated with CHD. It can be used for early diagnosis and severity assessment in adult patients with CHD-PAH.

Evaluation of the European Society of Cardiology/European Respiratory Society derived three- and four-strata risk stratification models in pulmonary arterial hypertension: introducing an internet-based risk stratification calculator

Aims

Estimation of prognosis in pulmonary arterial hypertension (PAH) has been influenced by that various risk stratification models use different numbers of prognostic parameters, as well as the lack of a comprehensive and time-saving risk assessment calculator. We therefore evaluated the various European Society of Cardiology (ESC)-/European Respiratory Society (ERS)-based three- and four-strata risk stratification models and established a comprehensive internet-based calculator to facilitate risk assessment.

Methods and results

Between 1 January 2000 and 26 July 2021, 773 clinical assessments on 169 incident PAH patients were evaluated at diagnosis and follow-ups. Risk scores were calculated using the original Swedish Pulmonary Arterial Hypertension Registry (SPAHR)/Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension (COMPERA) three-strata model, the updated SPAHR three-strata model with divided intermediate risk, and the simplified three-parameter COMPERA 2.0 four-strata model. The original SPAHR/COMPERA and the updated SPAHR models were tested for both 3-6 and 7-11 available parameters, respectively. Prognostic accuracy [area under the receiver operating characteristic (ROC) curve (AUC)] and Uno's cumulative/time-dependent C-statistics (uAUC) were calculated for 1-, 3-, and 5-year mortality. At baseline, both the original SPAHR/COMPERA and the updated SPAHR models, using up to six parameters, provided the highest accuracy (uAUC = 0.73 for both models) in predicting 1-, 3-, and 5-year mortality. At follow-ups, the updated SPAHR model with divided intermediate risk (7-11 parameters) provided the highest accuracy for 1-, 3-, and 5-year mortality (uAUC = 0.90), followed by the original SPAHR/COMPERA model (7-11 parameters) (uAUC = 0.88) and the COMPERA 2.0 model (uAUC = 0.85).

Conclusions

The present study facilitates risk assessment in PAH by introducing a comprehensive internet-based risk score calculator (https://www.svefph.se/risk-stratification). At baseline, utilizing the original or the updated SPAHR models using up to six parameters was favourable, the latter model additionally offering sub-characterization of the intermediate risk group. Our findings support the 2022 ESC/ERS pulmonary hypertension guidelines' strategy for risk stratification suggesting the utilization of a three-strata model at baseline and a simplified four-strata model at follow-ups. Our findings furthermore support the utility of the updated SPAHR model with divided intermediate risk, when a more comprehensive assessment is needed at follow-ups, complementing the three-parameter COMPERA 2.0 model. Larger multi-centre studies are encouraged to validate the utility of the updated SPAHR model.

Take home message

By introducing an internet-based risk score calculator (https://www.svefph.se/risk-stratification), risk assessment is facilitated. Our results support the 2022 ESC/ERS pulmonary hypertension guidelines' risk stratification strategy, additionally suggesting the updated SPAHR three-strata model with divided intermediate risk, as a promising complement to the new simplified three-parameter COMPERA 2.0 four-strata strategy, when a more comprehensive overview is needed.

Exploration of physical activity knowledge, preferences and support needs among pulmonary hypertension patients

OBJECTIVE

Physical activity (PA) is an established adjunct therapy for pulmonary hypertension (PH) patients to mitigate PH symptoms and improve quality of life. However, PA engagement within this population remains low. This study investigated PH patients' knowledge of PA, recalled advice, exercise preferences and PA support needs.

METHODS

Semi-structured interviews were conducted with 19 adults (mean age 50 years; SD ±12 years) diagnosed with PH, living in Ireland. Interview scripts were digitally recorded and transcribed verbatim. Thematic analysis was used to analyse the data.

RESULTS

Four key themes were identified: Lack of PA knowledge; exercise setting preference; accountability and monitoring; and clinician delivered PA information and guidance.

CONCLUSION

This study found that PH clinicians provide suboptimal PA advice, yet patients desired clinician-delivered PA guidance. Home-based exercise was preferred with monitoring and external accountability deemed as important to facilitate sustained engagement.

PRACTICE IMPLICATIONS

PH clinicians are well positioned to play a critical role in assisting and empowering PH patients to engage in PA. Providing training and education to PH clinicians regarding exercise prescription may be beneficial. Further research is needed to evaluate the feasibility and efficacy of home-based exercise interventions to improve quality of life and physical activity in PH.

Clinical characteristics and survival analysis of class I pulmonary arterial hypertension

PURPOSE

To analyze the clinical data and prognosis of patients with World Health Organization (WHO) functional class I pulmonary arterial hypertension (PAH).

METHODS

This research retrospectively analyzed the clinical data (baseline, laboratory as well as echocardiography and right heart catheterization data) of 63 class I PAH patients diagnosed and treated in the Department of Cardiology, First Affiliated Hospital of Zhengzhou University, between January 2021 and June 2022. The mean follow-up time was 10.7±6.5 months. The treatment and prognosis of the patients were analyzed.

RESULTS

Among the class I PAH patients, the average age at diagnosis was 39.7±12.7 years, with females accounting for 92.1%; 44.4% of patients were at grade III or IV; 55.6% were at medium-high risk. In the subgroup analysis, there were more cases with grade III/IV cardiac function (P=0.03) and high risk in idiopathic PAH (IPAH) group than those in congenital heart disease-associated (CHD-PAH) and connective tissue disease-associated PAH (CTD-PAH) groups (P=0.04). CHD-PAH patients tended to present with higher pulmonary systolic blood pressure, mean pulmonary artery pressure and pulmonary vascular resistance than CTD-PAH patients (P<0.01), while IPAH patients had worse right ventricular end-systolic and end-diastolic volumes (P<0.05). The three subgroups showed no obvious differences in echocardiographic indexes (right atrial size, right ventricular size and pulmonary artery systolic pressure) and related laboratory indexes (blood routines and hepatorenal function). In terms of the targeted drug therapy for PAH, the proportion of dual-drug combination therapy was the highest (48.1%), followed by monotherapy (35%) and triple combination therapy (15.9%). Nearly half (48.7%) of CTD-PAH cases were first diagnosed in the Rheumatology and Immunology Department, and all of them were given targeted drug therapy for PAH. After a mean follow-up of 10.7±6.5 months, a total of 8 endpoint events occurred, including 3 deaths due to CTD-PAH complicated with serious complications of other organs. The 1-year survival rate for all the included PAH patients was 95.2%.

CONCLUSIONS

In the era of targeted therapy, class I PAH patients in China have a high early survival rate, a high proportion of combined therapy and strong multidisciplinary attention.

Temporal Trends in Portopulmonary Hypertension Model for End-stage Liver Disease Exceptions and Outcomes

Model for end-stage liver disease (MELD) exception criteria for portopulmonary hypertension (POPH) were created to prioritize patients for liver transplant before POPH progression. Little is known about trends in POPH exception frequency, disease severity, pulmonary hypertension treatment patterns, or outcomes since the POPH MELD exception began.

Clinical application of risk assessment in PAH: Expert center APRN recommendations

Performing longitudinal and consistent risk assessments for patients with pulmonary arterial hypertension (PAH) is important to help guide treatment decisions to achieve early on and maintain a low-risk status and improve patient morbidity and mortality. Clinical gestalt or expert perception alone may over or underestimate a patient's risk status. Indeed, regular and continued use of validated risk assessment tools more accurately predict patients' survival. Effective PAH risk assessments are often underutilized even though many seasoned clinicians will attest to using these tools routinely. We present recommendations based on real-world experience in varied clinical practice settings around the United States for overcoming barriers to facilitate regular, serial formal risk assessment. Expert advanced practice provider clinicians from mid to large-size medical centers collaborated to formulate recommendations based on multiple discourses and discussions. Enlisting the help of support staff, such as medical assistants and nurses, to fill in available risk parameters in risk assessment tools can save time for providers and increase efficiency, as can technology-based solutions such as integrating risk assessments into electronic medical records. Modified, abbreviated risk assessment tools can be applied to a patient's clinical scenario when all of a patient's data are not available to complete a more comprehensive assessment. Initial discussions regarding the overall meaning and prognostic importance of risk scores may assist patients to take on a more active role in terms of informed decision-making regarding their care. A collaborative approach can help clinics establish consistent use of risk assessment.

DUSP5-mediated inhibition of smooth muscle cell proliferation suppresses pulmonary hypertension and right ventricular hypertrophy

Pulmonary hypertension (PH) is associated with structural remodeling of pulmonary arteries (PAs) because of excessive proliferation of fibroblasts, endothelial cells, and smooth muscle cells (SMCs). The peptide hormone angiotensin II (ANG II) contributes to pulmonary vascular remodeling, in part, through its ability to trigger extracellular signal-regulated kinase (ERK1/2) activation. Here, we demonstrate that the ERK1/2 phosphatase, dual-specificity phosphatase 5 (DUSP5), functions as a negative regulator of ANG II-mediated SMC proliferation and PH. In contrast to wild-type controls, Dusp5 null mice infused with ANG II developed PH and right ventricular (RV) hypertrophy. PH in Dusp5 null mice was associated with thickening of the medial layer of small PAs, suggesting an in vivo role for DUSP5 as a negative regulator of ANG II-dependent SMC proliferation. Consistent with this, overexpression of DUSP5 blocked ANG II-mediated proliferation of cultured human pulmonary artery SMCs (hPASMCs) derived from patients with idiopathic PH or from failed donor controls. Collectively, the data support a role for DUSP5 as a feedback inhibitor of ANG II-mediated ERK signaling and PASMC proliferation and suggest that disruption of this circuit leads to adverse cardiopulmonary remodeling.NEW & NOTEWORTHY Dual-specificity phosphatases (DUSPs) serve critical roles in the regulation of mitogen-activated protein kinases, but their functions in the cardiovascular system remain poorly defined. Here, we provide evidence that DUSP5, which resides in the nucleus and specifically dephosphorylates extracellular signal-regulated kinase (ERK1/2), blocks pulmonary vascular smooth muscle cell proliferation. In response to angiotensin II infusion, mice lacking DUSP5 develop pulmonary hypertension and right ventricular cardiac hypertrophy. These findings illustrate DUSP5-mediated suppression of ERK signaling in the lungs as a protective mechanism.

Echocardiography in Pulmonary Arterial Hypertension: Is It Time to Reconsider Its Prognostic Utility?

Pulmonary arterial hypertension (PAH) is characterized by an insult in the pulmonary vasculature, with subsequent right ventricular (RV) adaptation to the increased afterload that ultimately leads to RV failure. The awareness of the importance of RV function in PAH has increased considerably because right heart failure is the predominant cause of death in PAH patients. Given its wide availability and reduced cost, echocardiography is of paramount importance in the evaluation of the right heart in PAH. Several echocardiographic parameters have been shown to have prognostic implications in PAH; however, the role of echocardiography in the risk assessment of the PAH patient is limited under the current guidelines. This review discusses the echocardiographic evaluation of the RV in PAH and during therapy, and its prognostic implications, as well as the potential significant role of repeated echocardiographic assessment in the follow-up of patients with PAH.

Pulmonary hypertension and home-based (PHAHB) exercise intervention: protocol for a feasibility study

INTRODUCTION

Novel therapies for pulmonary hypertension (PH) have improved survival and slowed disease progression. However, patients still present with symptoms of exertional dyspnoea and fatigue, which impacts their ability to perform activities of daily living, reduces exercise tolerance and impairs their quality of life (QoL). Exercise training has shown to be safe and effective at enhancing QoL and physical function in PH patients, yet it remains an underused adjunct therapy. Most exercise training for PH patients has been offered through hospital-based programmes. Home-based exercise programmes provide an alternative model that has the potential to increase the availability and accessibility of exercise training as an adjunct therapy in PH. The purpose of this study is to investigate the feasibility, acceptability, utility and safety of a novel remotely supervised home-based PH exercise programme.

METHODS

Single arm intervention with a pre/post comparisons design and a follow-up maintenance phase will be employed. Eligible participants (n=25) will be recruited from the Mater Misericordiae University Hospital PH Unit. Participants will undergo a 10-week home-based exercise programme, with induction training, support materials, telecommunication support and health coaching sessions followed by a 10-week maintenance phase. The primary outcomes are feasibility, acceptability, utility and safety of the intervention. Secondary outcomes will include the impact of the intervention on exercise capacity, physical activity, strength, health-related QoL and exercise self-efficacy.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the Mater Misericordiae Institutional Review Board REF:1/378/2032 and Dublin City University Research Ethics DCUREC/2018/246. A manuscript of the results will be submitted to a peer-reviewed journal and results will be presented at conferences, community and consumer forums and hospital research conferences.

TRIAL REGISTRATION NUMBER

ISRCTN83783446; Pre-results.

Current Drug Treatment Strategies for Atrial Fibrillation and TASK-1 Inhibition as an Emerging Novel Therapy Option

Atrial fibrillation (AF) is the most common sustained arrhythmia with a prevalence of up to 4% and an upwards trend due to demographic changes. It is associated with an increase in mortality and stroke incidences. While stroke risk can be significantly reduced through anticoagulant therapy, adequate treatment of other AF related symptoms remains an unmet medical need in many cases. Two main treatment strategies are available: rate control that modulates ventricular heart rate and prevents tachymyopathy as well as rhythm control that aims to restore and sustain sinus rhythm. Rate control can be achieved through drugs or ablation of the atrioventricular node, rendering the patient pacemaker-dependent. For rhythm control electrical cardioversion and pharmacological cardioversion can be used. While electrical cardioversion requires fasting and sedation of the patient, antiarrhythmic drugs have other limitations. Most antiarrhythmic drugs carry a risk for pro-arrhythmic effects and are contraindicated in patients with structural heart diseases. Furthermore, catheter ablation of pulmonary veins can be performed with its risk of intraprocedural complications and varying success. In recent years TASK-1 has been introduced as a new target for AF therapy. Upregulation of TASK-1 in AF patients contributes to prolongation of the action potential duration. In a porcine model of AF, TASK-1 inhibition by gene therapy or pharmacological compounds induced cardioversion to sinus rhythm. The DOxapram Conversion TO Sinus rhythm (DOCTOS)-Trial will reveal whether doxapram, a potent TASK-1 inhibitor, can be used for acute cardioversion of persistent and paroxysmal AF in patients, potentially leading to a new treatment option for AF.

Current clinical utilization of risk assessment tools in pulmonary arterial hypertension: a descriptive survey of facilitation strategies, patterns, and barriers to use in the United States

Practice guidelines suggest that treatment decisions in pulmonary arterial hypertension be informed by periodic assessment of patients' clinical risk. Several tools, well validated for risk discrimination, such as the Registry to Evaluate Early and Long-term Pulmonary Arterial Hypertension Disease Management calculator, were developed to assess pulmonary arterial hypertension patients' risk of death based on multiple parameters, including functional class, hemodynamics, biomarkers, comorbidities, and exercise capacity. Using an online survey, we investigated the use of risk assessment tools by pulmonary hypertension healthcare providers in the United States. Of 121 survey respondents who make treatment decisions, 59% reported using risk assessment tools. The use of these tools was lower for non-physicians (48% vs. 65% physicians) and for practitioners at centers with 1 to 100 pulmonary arterial hypertension patients compared with centers with >100 patients (47% vs. 64%). Risk was most frequently assessed by decision makers at the time of diagnosis (cited by 54%) and at the time of worsening symptoms (cited by 42%), suggesting that use of pulmonary arterial hypertension risk assessment tools remains low. In our survey, non-physicians compared with physicians cited two major barriers to increased tool use: lack of education and training (20% vs. 4%) and lack of clarity on the best tool to use (30% vs. 18%). Information technology tools, such as electronic medical record integration and web or phone-based risk calculating applications, were cited most frequently as ways to increase the use of risk assessment tools.

Oxygen and pulmonary arterial hypertension: effects, mechanisms, and therapeutic benefits

Oxygen is a pulmonary vasodilator. Although treatment of pulmonary arterial hypertension (PAH) is focused on pulmonary vasodilation, treatment guidelines do not recommend O2 therapy for patients unless they develop hypoxaemia. These guidelines point to a lack of evidence of benefit of O2 therapy from randomized controlled trials (RCTs) and to evidence of lack of benefit in a single RCT involving patients with Eisenmenger syndrome. These guidelines did not identify major limitations with the Eisenmenger study or consider other evidence of therapeutic benefit. Recent advances in mechanistic understanding of O2 effects on pulmonary vascular tone, along with substantial evidence of acute effects of O2 in PAH patients, challenge the view that benefits of O2 arise only through correction of hypoxaemia. Evidence presented in this review shows that O2 acts as a pulmonary vasodilator in patients who are normoxaemic; that this probably involves an alveolar mechanism in addition to a blood-borne (oxyhaemoglobin) mechanism; and that therapeutic benefit of O2 does not depend on arterial O2 levels. This suggests that O2 has potential therapeutic benefit for all patients with PAH. Clinical guidelines and practice related to O2 therapy need to be reassessed, and further research is needed.

Efficacy and safety of riociguat in combination therapy for patients with pulmonary arterial hypertension (PATENT studies)

Many patients with pulmonary arterial hypertension do not achieve treatment goals with monotherapy, and therefore combination therapy is becoming the standard of care. The soluble guanylate cyclase stimulator riociguat is licensed for the treatment of pulmonary arterial hypertension; here we present findings from patients who were receiving combined riociguat plus endothelin receptor antagonists or non-intravenous prostanoids in the randomized, placebo-controlled PATENT-1 study and its open-label extension (PATENT-2). Moreover, we include new data from patients receiving early sequential combination therapy (three to six months of endothelin receptor antagonist treatment) or long-term background endothelin receptor antagonist therapy (>6 months). Patients were randomized to riociguat 2.5 mg–maximum (N = 131 pretreated patients) and placebo (N = 60 pretreated patients). Riociguat improved 6-min walking distance (PATENT-1 primary endpoint), functional capacity, and hemodynamics after 12 weeks in pretreated patients. The placebo-corrected changes in 6-min walking distance were +24 m in endothelin receptor antagonist-pretreated patients and +106 m in the small group of prostanoid-pretreated patients. In the early sequential combination and long-term background endothelin receptor antagonist groups, the placebo-corrected changes in 6-min walking distance were +65 m (95% CI: 17 to 113 m) and +13 m (95% CI: –8 to 33 m), respectively. In conclusion, these data suggest that early sequential combination of an endothelin receptor antagonist plus riociguat is a feasible treatment option. Both early sequential therapy and long-term background endothelin receptor antagonist plus riociguat were well tolerated in the PATENT studies.

Transitions between infused and oral prostacyclin pathway agents in pulmonary arterial hypertension: key considerations

Prostacyclin pathway agents are a critical treatment for patients with pulmonary arterial hypertension. Seven prostacyclin pathway agents are available, including agents administered by parenteral infusion, by inhalation, and orally. Pulmonary arterial hypertension patients are now transitioned from one prostacyclin pathway agent to another with increasing frequency. Such transitions require careful downtitration and uptitration to avoid decompensation from rapid withdrawal and to achieve a patient's optimal dose based on efficacy and tolerability. Clinical guidance is especially lacking for transitions involving the newer, oral prostacyclin pathway agents; specifically, selexipag and oral treprostinil. We present three case reports of patients with pulmonary arterial hypertension who underwent one or more transition between parenteral and oral prostacyclin pathway agents, including some transitions that were successful and some that were not. These cases illustrate key considerations, such as titration protocols, patient selection, side effect management, and pharmacokinetics.

Serial Measurements of N-Terminal Pro-B-Type Natriuretic Peptide Serum Level for Monitoring Pulmonary Arterial Hypertension in Children

OBJECTIVE

To assess the association between serially measured N-terminal pro-B-type natriuretic peptide (NT-proBNP) serum levels and disease severity in children with pulmonary arterial hypertension (PAH), and to assess its predictive value for death or (heart-)lung transplantation.

STUDY DESIGN

This was a longitudinal cohort study of the Dutch National Network for Pediatric Pulmonary Hypertension conducted between 2003 and 2017. Data on NT-proBNP and disease severity markers (World Health Organization Functional Class [WHO-FC], 6-minute walking distance [6MWD], and tricuspid annular plane systolic excursion [TAPSE]) were collected every 3 to 6 months from 82 children with PAH. The outcome measure was death or (heart-)lung transplantation. Also, NT-proBNP levels over time were compared between survivors and nonsurvivors.

RESULTS

The median patient age was 8.8 years (IQR, 4.6-13.5 years), and 61% were female. The median duration of follow-up was 4.8 years (IQR, 1.9-10.0 years). At all times during the course of disease, higher NT-proBNP levels were associated with higher WHO-FC (β = 0.526; 95% CI, 0.451-0.600), lower 6MWD z-score (β = -0.587; 95% CI, -0.828 to -0.346), lower TAPSE z-score (β = -0.783; 95% CI, -1.016 to -0.549), and elevated risk of death or (heart-)lung transplantation (hazard ratio 16.61; 95% CI, 7.81-35.33). Compared with survivors, nonsurvivors had NT-proBNP levels that were higher at first measurement and increased exponentially over time (P = .005). Changes in NT-proBNP serum level over time were predictive of outcome.

CONCLUSIONS

Throughout the disease course of pediatric PAH, serial measurements of NT-proBNP are associated with disease severity and transplant-free survival. Monitoring NT-proBNP levels over time provides important prognostic information that can support clinical decision making in combination with other established prognostic markers.

Advances in medical therapy for pulmonary arterial hypertension

PURPOSE OF REVIEW

The purpose of this review is to demonstrate advances in the medical treatment of pulmonary arterial hypertension (PAH). Reviewed will be the evidence that favors the use of risk assessment in the treatment of PAH. Optimization of combination therapy depending on the risk or worsening will be reviewed. Finally, recent advances in new treatment strategies will be mentioned.

RECENT FINDINGS

The use of therapies in sequence or in combination for the treatment of PAH has been shown to decrease morbidity and mortality. Tailoring these treatment strategies to a risk of worsening has been shown to decrease mortality and time to clinical worsening because of PAH. In addition, there have been several advances in the development of other medications separate from the three known pathogenic pathways in PAH.

SUMMARY

In the last 15 years, 12 specific therapies have been approved for PAH. These therapies target three separate pathogenic pathways [the endothelin (ET), nitric oxide (NO) and prostacyclin (PGI2)]. As a result, treatment guidelines have tailored the treatment of PAH with these medications either as single drug therapy or in combination. Recently, other treatment pathways have been explored as new strategies for the treatment of PAH.

Systems Analysis of the Human Pulmonary Arterial Hypertension Lung Transcriptome

Pulmonary arterial hypertension (PAH) is characterized by increased pulmonary artery pressure and vascular resistance, typically leading to right heart failure and death. Current therapies improve quality of life of the patients but have a modest effect on long-term survival. A detailed transcriptomics and systems biology view of the PAH lung is expected to provide new testable hypotheses for exploring novel treatments. We completed transcriptomics analysis of PAH and control lung tissue to develop disease-specific and clinical data/tissue pathology gene expression classifiers from expression datasets. Gene expression data were integrated into pathway analyses. Gene expression microarray data were collected from 58 PAH and 25 control lung tissues. The strength of the dataset and its derived disease classifier was validated using multiple approaches. Pathways and upstream regulators analyses was completed with standard and novel graphical approaches. The PAH lung dataset identified expression patterns specific to PAH subtypes, clinical parameters, and lung pathology variables. Pathway analyses indicate the important global role of TNF and transforming growth factor signaling pathways. In addition, novel upstream regulators and insight into the cellular and innate immune responses driving PAH were identified. Finally, WNT-signaling pathways may be a major determinant underlying the observed sex differences in PAH. This study provides a transcriptional framework for the PAH-diseased lung, supported by previously reported findings, and will be a valuable resource to the PAH research community. Our investigation revealed novel potential targets and pathways amenable to further study in a variety of experimental systems.

Medication adherence, hospitalization, and healthcare resource utilization and costs in patients with pulmonary arterial hypertension treated with endothelin receptor antagonists or phosphodiesterase type-5 inhibitors

Adherence to therapy for pulmonary arterial hypertension is essential to optimize patient outcomes, but data on real-world adherence to different pulmonary arterial hypertension drug classes are limited. This retrospective database analysis evaluated relationships between adherence, hospitalization, and healthcare costs in pulmonary arterial hypertension patients treated with endothelin receptor antagonists or phosphodiesterase type-5 inhibitors. From the IQVIA Adjudicated Health Plan Database, patients with pulmonary arterial hypertension were identified based on diagnostic codes and prescriptions for endothelin receptor antagonists (ambrisentan, bosentan, macitentan) or phosphodiesterase type-5 inhibitors (sildenafil, tadalafil) approved for pulmonary arterial hypertension. Patients were assigned to the class of their most recently initiated (index) pulmonary arterial hypertension therapy between 1 January 2009 and 30 June 2015. Medication adherence was measured by proportion of days covered; patients with proportion of days covered ≥80% were considered adherent. The proportion of adherent patients was higher for endothelin receptor antagonists (571/755; 75.6%) than for phosphodiesterase type-5 inhibitors (970/1578; 61.5%; P < 0.0001). In both groups, hospitalizations declined as proportion of days covered increased. Among adherent patients, those on endothelin receptor antagonists had a significantly lower hospitalization rate than those on phosphodiesterase type-5 inhibitors (23.1% versus 28.5%, P = 0. 0218), fewer hospitalizations (mean (standard deviation) 0.4 (0.8) versus 0.5 (0.9); P = 0.02), and mean hospitalization costs during the six-month post-index ($9510 versus $15,726, P = 0.0318). Increasing adherence reduced hospitalization risk more for endothelin receptor antagonists than for phosphodiesterase type-5 inhibitors (hazard ratio 0.176 versus 0.549, P = 0.001). Rates and numbers of rehospitalizations within 30 days post-discharge were similar between groups. Mean total costs were higher with endothelin receptor antagonists than phosphodiesterase type-5 inhibitors in all patients ($91,328 versus $72,401, P = 0.0003) and in adherent patients ($88,867 versus $56,300, P < 0.0001), driven by higher drug costs.

Comparative effectiveness of pulmonary arterial hypertension drugs in treatment-naive patients: a network meta-analysis

Aim: No network meta-analysis has been conducted to study efficacy of drug therapies specific for treatment of pulmonary arterial hypertension in treatment-naive patients only. Methods: Randomized controlled trials on pulmonary arterial hypertension-specific drug therapies were searched and a Bayesian network meta-analysis was performed. The 6-min walking distance (6MWD) and all-cause mortality were efficacy outcomes, whereas discontinuation due to adverse events was a safety-related outcome. Results: Analysis included 3.713 patients from 21 trials. Combination of ambrisentan and tadalafil showed the greatest impact on 6MWD, followed by epoprostenol and intravenous treprostinil (high dose). The latter two demonstrated marked effect size on mortality, although not statistically significant. Conclusion: According to 6MWD, ambrisentan/tadalafil combination was considered as most effective among all comparisons. Prospero ID: CRD42019110832.

[Risk stratification methods and their significance in pulmonary arterial hypertension]

Despite significant advances in therapy, pulmonary arterial hypertension (PAH) remains a progressive disease with a poor prognosis. Immediately after establishing the diagnosis of PAH, urgent treatment with PAH-specific therapy is required. Due to the progressive nature of the disease, all patients should be closely monitored and their treatment regimen should be promptly changed according to clinical need. Risk stratification is an important method for informing the clinician and the patient about the prognosis of disease and the choice of therapy methods. The REVEAL scale and the ESC/ERS 2015 risk assessment table are important multifactorial tools for making decisions about the prescription and correction of PAH therapy, as well as for assessment of patients' response to therapy. Current guidelines for PAH indicate that the most important task of treatment of PAH is to achieve the low - risk status.

Current status of pulmonary arterial hypertension in Korea

Pulmonary arterial hypertension (PAH) is characterized by remodeling of the distal pulmonary arteries resulting in high pulmonary vascular resistance and, eventually, right ventricular heart failure. Although current advances in PAH therapy have improved outcomes, poor survival remains a reality worldwide, including Korea. One of the most important issues in PAH is the late diagnosis, since screening or diagnostic efforts are often overlooked due to the rarity of disease. Data from Korean registries and observational cohorts show that delayed detection leads to increased morbidity. Additionally, low percentages of Korean patients are committed to intensive PAH-targeted therapy. Current Korean health insurance policies' lack of coverage for new PAH-targeted drugs and upfront combination therapy may also hamper the improvement of treatment outcomes. Understanding individual variability in response to therapeutics through deep phenotyping is a novel strategy that should be considered when treating PAH. Overall, early detection of PAH by proactive screening together with early, intensive, individualized PAH therapy using deep phenotyping is crucial for improving prognoses for PAH patients in Korea.

Endothelin and the heart in health and diseases

Endothelin-1 (ET-1), a 21-amino acid peptide, was initially identified in 1988 as a potent vasoconstrictor and pressor substance isolated from the culture supernatant of porcine aortic endothelial cells. From human genomic DNA analysis, two other family peptides, ET-2 and ET-3, were found. They showed different effects and distribution, suggesting that each peptide may play separate roles in different organs. In the heart, ET-1 also causes positive inotropic and chronotropic responses and hypertrophic activity of the cardiomyocytes. ETs act via activation of two receptor subtypes, ET_A and ET_B receptors, both of which are coupled to various GTP-binding proteins depending on cell types. Endogenous ET-1 may be involved in progression of various cardiovascular diseases. ET antagonists are currently used clinically in the treatment for patients with pulmonary hypertension, and are considered to have further target diseases as heart failure, cardiac hypertrophy and other cardiac diseases, renal diseases, systemic hypertension, and cerebral vasospasm.

Characterization and regulation of wild-type and mutant TASK-1 two pore domain potassium channels indicated in pulmonary arterial hypertension

Key points

The TASK‐1 channel gene (KCNK3) has been identified as a possible disease‐causing gene in heritable pulmonary arterial hypertension (PAH).

In the present study, we show that novel mutated TASK‐1 channels, seen in PAH patients, have a substantially reduced current compared to wild‐type TASK‐1 channels.

These mutated TASK‐1 channels are located at the plasma membrane to the same degree as wild‐type TASK‐1 channels.

ONO‐RS‐082 and alkaline pH 8.4 both activate TASK‐1 channels but do not recover current through mutant TASK‐1 channels.

We show that the guanylate cyclase activator, riociguat, a novel treatment for PAH, enhances current through TASK‐1 channels but does not recover current through mutant TASK‐1 channels.

Abstract

Pulmonary arterial hypertension (PAH) affects ∼15–50 people per million. KCNK3, the gene that encodes the two pore domain potassium channel TASK‐1 (K2P3.1), has been identified as a possible disease‐causing gene in heritable PAH. Recently, two new mutations have been identified in KCNK3 in PAH patients: G106R and L214R. The present study aimed to characterize the functional properties and regulation of wild‐type (WT) and mutated TASK‐1 channels and determine how these might contribute to PAH and its treatment. Currents through WT and mutated human TASK‐1 channels transiently expressed in tsA201 cells were measured using whole‐cell patch clamp electrophysiology. Localization of fluorescence‐tagged channels was visualized using confocal microscopy and quantified with in‐cell and on‐cell westerns. G106R or L214R mutated channels were located at the plasma membrane to the same degree as WT channels; however, their current was markedly reduced compared to WT TASK‐1 channels. Functional current through these mutated channels could not be restored using activators of WT TASK‐1 channels (pH 8.4, ONO‐RS‐082). The guanylate cyclase activator, riociguat, enhanced current through WT TASK‐1 channels; however, similar to the other activators investigated, riociguat did not have any effect on current through mutated TASK‐1 channels. Thus, novel mutations in TASK‐1 seen in PAH substantially alter the functional properties of these channels. Current through these channels could not be restored by activators of TASK‐1 channels. Riociguat enhancement of current through TASK‐1 channels could contribute to its therapeutic benefit in the treatment of PAH.

The TASK‐1 channel gene (KCNK3) has been identified as a possible disease‐causing gene in heritable pulmonary arterial hypertension (PAH).

In the present study, we show that novel mutated TASK‐1 channels, seen in PAH patients, have a substantially reduced current compared to wild‐type TASK‐1 channels.

These mutated TASK‐1 channels are located at the plasma membrane to the same degree as wild‐type TASK‐1 channels.

ONO‐RS‐082 and alkaline pH 8.4 both activate TASK‐1 channels but do not recover current through mutant TASK‐1 channels.

We show that the guanylate cyclase activator, riociguat, a novel treatment for PAH, enhances current through TASK‐1 channels but does not recover current through mutant TASK‐1 channels.

Pulmonary Arterial Hypertension: Combination Therapy in Practice

Combination therapy is now regarded as the standard of care in pulmonary arterial hypertension (PAH) and is becoming widely used in clinical practice. Given the inherent complexities of combining medications, there is a need for practical advice on implementing this treatment strategy in the clinic. Drawing on our experience and expertise, within this review, we discuss some of the challenges associated with administration of combination therapy in PAH and how these can be addressed in the clinic. Despite their differing modes of action, all of the currently available classes of PAH therapy induce systemic vasodilation. In initial combination therapy regimens in particular, this may lead to additive side effects and reduced tolerability compared with monotherapy. However, approaches such as staggered treatment initiation and careful up-titration may reduce the risk of additive side effects and have been used successfully in clinical practice, as well as in clinical trials and registry studies. When combination therapy regimens are initiated, it is important that patients are monitored regularly for the presence of any side effects and that these are then managed promptly and appropriately. For patients to attain the best outcomes, the treatment regimen must be tailored to the individual’s specific needs, including consideration of PAH etiology, the presence of comorbidities and concomitant medications beyond PAH therapy, and patient lifestyle and preference. It is also vital that individuals are managed at expert care centers, where multidisciplinary teams have a wealth of specialist experience in treating PAH patients. Adherence to therapy can be a concern in a chronic disease such as PAH, and as treatment regimens become increasingly complex, maintaining good treatment adherence may become more challenging. It is essential that patients are educated on the importance of treatment adherence, and this is a key role for the PAH nurse specialist. For patients who are managed carefully in expert centers with combination therapy regimens that are tailored to their specific needs, a favorable benefit–risk ratio can be achieved. With individual and carefully managed approaches, the excellent results observed with combination therapy in clinical trials can be obtained by patients in a real-world setting.