Development and Validation of an Abridged Version of the REVEAL 2.0 Risk Score Calculator, REVEAL Lite 2, for Use in Patients With Pulmonary Arterial Hypertension

Clinical outcomes of upfront combination therapy for portopulmonary hypertension

Background

Limited data exists on upfront combination therapy for portopulmonary hypertension. We evaluated the clinical efficacy, long-term outcomes, and safety of upfront combination therapy in patients with portopulmonary hypertension.

Methods

We performed a retrospective, single-center cohort study involving a final analysis of 33 consecutive patients diagnosed with portopulmonary hypertension who were taking pulmonary arterial hypertension-specific medication. We compared hemodynamic parameters, risk profiles, composite clinical worsening events, and safety between monotherapy (n = 23) and upfront combination therapy (n = 10).

Results

Twenty-seven patients (82 %) were classified into the Child-Pugh A stage. The change ratios of pulmonary vascular resistance (-32 % vs. -57 %, P = 0.006) were significantly better with upfront combination therapy. Upfront combination therapy also showed significant improvement in risk profiles. Kaplan-Meier analysis showed that the composite event-free rate was significantly lower in patients who received upfront combination therapy than in those who received monotherapy (P = 0.016), although no statistical differences were observed in all-cause death. In the univariate Cox proportional hazards analysis, upfront combination therapy was a factor for decreasing composite clinical worsening outcomes (hazard ratio 0.190, 95 % confidence interval 0.042-0.854; P = 0.030). No significant hepatic impairments were observed over 2 years of follow-up in the upfront combination group.

Conclusions

In patients with portopulmonary hypertension, upfront combination therapy significantly improved symptoms and short-term hemodynamics, and reduced long-term clinical worsening events without serious adverse effects. This study's findings suggest that patients with portopulmonary hypertension presenting with mild hepatic impairment benefit from upfront combination therapy.

Comparison Between REVEAL Lite 2 and COMPERA 2.0 for Risk Stratification in Pulmonary Arterial Hypertension

BACKGROUND

Risk stratification is the cornerstone of the management of pulmonary arterial hypertension (PAH). Current European Society of Cardiology/European Respiratory Society guidelines recommend using the Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension (COMPERA) three-strata risk model at baseline and the COMPERA 2.0 four-strata model at follow-up. However, the guidelines did not take into consideration other available risk scores such as the Registry to Evaluate Early and Long-Term PAH Disease Management (REVEAL) Lite 2.

RESEARCH QUESTION

Is REVEAL Lite 2 better at discriminating risk than the COMPERA risk assessment models at baseline or follow-up evaluations?

STUDY DESIGN AND METHODS

This study analyzed data from patients with PAH consecutively enrolled between June 2011 and February 2022 in the PAH registry at our expert Pulmonary Hypertension Center. Patients were stratified according to REVEAL Lite 2 and COMPERA three- and four-strata risk scores at baseline and follow-up to predict the composite outcome for lung transplantation or death. Receiver-operating characteristic curves in predicting the binary outcome at 3, 5, and 7 years were plotted. Areas under the curve of the scores were compared by using the χ2 test. The performance of the scores was determined according to the Harrel C statistic.

RESULTS

A total of 296 patients were included for baseline and 196 for follow-up evaluation. The overall transplant-free survival in the patient population at 1, 3, 5, and 7 years was 93.6%, 81.3%, 75.1%, and 68.8%, respectively. At baseline, the C statistic of REVEAL Lite 2 was 0.74 (95% CI, 0.69-0.80), compared with 0.68 (95% CI, 0.63-0.74) for the COMPERA four-strata model and 0.63 (95% CI, 0.58-0.69) for the COMPERA three-strata model. All C statistic differences between REVEAL Lite 2 and the other models were statistically significant at baseline.

INTERPRETATION

Our analysis showed that REVEAL Lite 2 was better at baseline at discriminating risk in this patient population. Future guidelines should consider including REVEAL Lite 2 in the management algorithm to help clinicians make informed decisions. Further analysis in larger cohorts could help validate these findings.

Non-invasive prediction of pulmonary vascular disease-related exercise intolerance and survival in non-group 1 pulmonary hypertension

AIMS

The clinical utility of pulmonary hypertension (PH) risk scores in non-group 1 PH with pulmonary vascular disease (PVD) remains unresolved.

METHODS AND RESULTS

We utilized the prospective multicenter PVDOMICS cohort with group 2, 3, 4 or 5 PH-related PVD and calculated group 1 PH risk scores (REVEAL 2.0, REVEAL Lite 2, French registry score and COMPERA 2). The c-statistic to predict death was compared separately in (i) pre-capillary PH groups 3/4/5, and (ii) combined post- and pre-capillary PH group 2. Exercise right heart catheterization reserve, ventricular interdependence and right ventricular-pulmonary artery (RV-PA) coupling were compared across risk categories. Among 449 individuals with group 3/4/5 PH, the REVEAL 2.0 risk score had the highest c-statistic for predicting death (0.699, 95% confidence interval [CI] 0.660-0.737, p < 0.0001) with comparable performance using the simpler REVEAL Lite 2 score (0.695, 95% CI 0.656-0.734, p < 0.0001). The French and COMPERA 2 risk scores were also predictive of mortality, but performance of both was statistically inferior to REVEAL 2.0 (c-statistic difference -0.072, 95% CI -0.123 to -0.020, p = 0.006, and -0.043, 95% CI -0.067 to -0.018, p = 0.0007, respectively). RV function and RV-PA coupling measures were prognostic in isolation, but did not add incremental value to REVEAL (p > 0.50 for all). Findings were similar in patients with group 2 PH (n = 239). Stratification by the REVEAL Lite 2 score non-invasively identified non-group 1 PH with more advanced PVD with worse exercise capacity, RV-PA uncoupling, ventricular interdependence and impaired cardiac output reserve (p < 0.05 for all).

CONCLUSIONS

Non-invasive REVEAL risk predicts mortality in non-group 1 PH without incremental prognostic value from detailed RV function or RV-PA coupling assessment. Baseline REVEAL Lite 2 risk stratification non-invasively identifies greater pulmonary vascular dysfunction and right heart-related exercise limitation, which may help guide patient selection for targeted pulmonary vascular therapies in non-group 1 PH.

Using Sotatercept in the Care of Patients With Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare disease of the pulmonary microvasculature leading to elevated precapillary pulmonary hypertension. Pulmonary vascular remodeling, a characteristic of PAH, is driven by dysfunctions in the signaling between the pulmonary smooth muscle and endothelial cells with abnormalities that affect cell proliferation and immune dysregulation. Sotatercept, an activin signaling inhibitor, has recently been approved by the US Food and Drug Administration for the treatment of PAH based on two pivotal clinical trials. Evidence-based clinical trials have provided a framework to guide clinicians treating the disease; however, they are not tailored to the individual patient. Often, recommendations from these data are unclear or too general, due to remaining gaps in knowledge. In this edition of "How I Do It," we provide a case-based discussion of common clinical decisions regarding diagnostic testing, choice of first-line agents, escalation of therapy, potential timing of sotatercept, safety awareness, practical use, potential management changes, and the future use of sotatercept in other pulmonary hypertension cohorts.

Initial combination therapy with macitentan and tadalafil in patients with pulmonary arterial hypertension, with and without cardiac comorbidities

AIMS

According to current guidelines, initial monotherapy should be considered for pulmonary arterial hypertension (PAH) patients with cardiopulmonary comorbidities. This analysis of combined data from the TRITON and REPAIR clinical trials, assesses efficacy and safety of initial double combination therapy in patients without vs. with 1-2 cardiac comorbidities.

METHODS AND RESULTS

Data were combined for patients from TRITON (NCT02558231) and REPAIR (NCT02310672) on initial macitentan and tadalafil double combination therapy (overall set, n = 148) and two subgroups defined as patients without cardiac comorbidities (n = 62) and those with 1-2 cardiac comorbidities (n = 78). Patients with ≥3 comorbidities were excluded from these studies. For the overall set, the median (Q1-Q3) duration of combined macitentan and tadalafil exposure was 513.0 (364.0-778.0) days, and was similar between subgroups. Change from baseline to Week 26 for pulmonary vascular resistance was -55% and -50% for patients without and with 1-2 cardiac comorbidities, respectively; marked improvements in other hemodynamic and functional parameters were also observed, although functional parameters improved to a lesser extent in patients with comorbidities. At Week 26, the majority of patients had improved PAH risk status, according to the non-invasive four-strata and REVEAL Lite 2.0 methods. The safety profile of initial macitentan plus tadalafil combination therapy was consistent with the known profiles of the two drugs, and similar between the subgroups.

CONCLUSIONS

Initial double combination therapy with macitentan plus tadalafil is efficacious in patients with PAH with 1-2 cardiac comorbidities and those without, with similar safety and tolerability profiles between the two groups.

Prognostic Value of Serial Risk Stratification in Adult and Pediatric Pulmonary Arterial Hypertension: A Systematic Review

BACKGROUND

In pulmonary arterial hypertension, it is recommended to base therapeutic decisions on risk stratification. This systematic review aims to report the prognostic value of serial risk stratification in adult and pediatric pulmonary arterial hypertension and to explore the usability of serial risk stratification as treatment target.

METHODS AND RESULTS

Electronic databases PubMed, Embase, and Web of Science were searched up to January 30, 2023, using terms associated with pulmonary arterial hypertension, pediatric pulmonary hypertension, and risk stratification. Observational studies and clinical trials describing risk stratification at both baseline and follow-up were included. Sixty five studies were eligible for inclusion, including only 2 studies in a pediatric population. C-statistic range at baseline was 0.31 to 0.77 and improved to 0.30 to 0.91 at follow-up. In 53% of patients, risk status changed (42% improved, 12% worsened) over 168 days (interquartile range, 137-327 days; n=22 studies). The average proportion of low-risk patients increased from 18% at baseline to 36% at a median follow-up of 244 days (interquartile range, 140-365 days; n=40 studies). In placebo-controlled drug studies, risk statuses of the intervention groups improved more and worsened less compared with the placebo groups. Furthermore, a low-risk status, but also an improved risk status, at follow-up was associated with a better outcome. Similar results were found in the 2 pediatric studies.

CONCLUSIONS

Follow-up risk stratification has improved prognostic value compared with baseline risk stratification, and change in risk status between baseline and follow-up corresponded to a change in survival. These data support the use of serial risk stratification as treatment target in pulmonary arterial hypertension.

Characteristics and risk profiles of patients with pulmonary arterial or chronic thromboembolic pulmonary hypertension living permanently at >2500 m of high altitude in Ecuador

Over 80 Mio people worldwide live >2500 m, including at least as many patients with pulmonary vascular disease (PVD), defined as pulmonary arterial or chronic thromboembolic pulmonary hypertension (PAH/CTEPH), as elsewhere (estimated 0.1‰). Whether PVD patients living at high altitude have altered disease characteristics due to hypobaric hypoxia is unknown. In a cross-sectional study conducted at the Hospital Carlos Andrade Marin in Quito, Ecuador, located at 2840 m, we included 36 outpatients with PAH or CTEPH visiting the clinic from January 2022 to July 2023. We collected data on diagnostic right heart catheterization, treatment, and risk factors, including NYHA functional class (FC), 6-min walk distance (6MWD), and NT-brain natriuretic peptide (BNP) at baseline and at last follow-up. Thirty-six PVD patients (83% women, 32 PAH, 4 CTEPH, mean ± SD age 44 ± 13 years, living altitude 2831 ± 58 m) were included and had the following baseline values: PaO2 8.2 ± 1.6 kPa, PaCO2 3.9 ± 0.5 kPa, SaO2 91 ± 3%, mean pulmonary artery pressure 53 ± 16 mmHg, pulmonary vascular resistance 16 ± 4 WU, 50% FC II, 50% FC III, 6MWD 472 ± 118 m, BNP 490 ± 823 ng/L. Patients were treated for 1628 ± 1186 days with sildenafil (100%), bosentan (33%), calcium channel blockers (33%), diuretics (69%), and oxygen (nocturnal 53%, daytime 11%). Values at last visit were: FC (II 75%, III 25%), 6MWD of 496 ± 108 m, BNP of 576 ± 5774 ng/L. Compared to European PVD registries, ambulatory PVD patients living >2500 m revealed similar blood gases and relatively low and stable risk factor profiles despite severe hemodynamic compromise, suggesting that favorable outcomes are achievable for altitude residents with PVD. Future studies should focus on long-term outcomes in PVD patients dwelling >2500 m.

Prognostic role of haemodynamics at follow-up in patients with pulmonary arterial hypertension: a challenge to current European Society of Cardiology/European Respiratory Society risk tools

Background

Haemodynamic variables like right atrial pressure (RAP), cardiac index (CI), stroke volume index (SVI) and mixed venous oxygen saturation (S vO2 ) predict survival in patients with pulmonary arterial hypertension (PAH). However, there is the need to identify further prognostic haemodynamic parameters as well as to redefine their role in PAH risk stratification compared to current risk tools and non-invasive parameters.

Methods

This cohort study includes treatment-naïve patients assessed at baseline and after first-line PAH therapy with clinical, functional, exercise, laboratory and haemodynamic evaluations. Using a stepwise multivariate Cox regression analysis, independent prognostic haemodynamic parameters were identified and stratified according to cut-offs already defined in the European Society of Cardiology (ESC)/European Respiratory Society (ERS) risk table or defined based on the highest Chi-squared of the log-rank test. Their discriminatory power was tested for all-cause death and a combined end-point of death, hospitalisation and need of treatment escalation.

Results

794 patients with PAH were enrolled. At first follow-up, RAP and pulmonary artery elastance were independently associated with death. Because of high correlations between haemodynamic parameters, different multivariable analyses were done identifying six other variables (pulmonary arterial compliance, cardiac efficiency, pulmonary vascular resistance, S vO2 , CI and SVI). Haemodynamic parameters were of no added prognostic value compared to ESC/ERS risk tools for the all-cause death end-point but they showed additional value to non-invasive parameters for the combined end-point and, when taken alone, had a discriminatory capacity comparable to ESC/ERS risk tools.

Conclusion

Haemodynamics' discriminative ability for clinical worsening is comparable to current ESC/ERS risk tools and is of added value to non-invasive parameters.

Mortality Risk Assessment Using the REVEAL 2.0 Score in Pulmonary Hypertension Secondary to Left Heart Disease

Background

Pulmonary hypertension (PH) frequently complicates the course of patients with left heart disease (PH-LHD) and is associated with worse clinical outcomes. Mortality calculators for PH-LHD are lacking, and it is unclear whether any risk prediction tools originally derived from other forms of PH can accurately predict outcomes in patients with PH-LHD.

Methods

We retrospectively analyzed data from 161 patients diagnosed with PH-LHD referred to our pulmonary hypertension center from 2016 to 2022. We calculated the Registry to Evaluate Early and Long-Term PAH Disease Management (REVEAL 2.0) risk score and categorized patients as low, intermediate, or high-risk. We assessed survival at 1 and 3 years using Kaplan-Meier and Cox proportional hazards, as well as classification performance using a concordance index.

Results

At the first outpatient visit, 15% of patients were stratified as low-risk, 27% as intermediate, and 57% as high-risk. Cumulative 1-year survival rates were 100%, 94%, and 91% for the low, intermediate, and high-risk strata, respectively. Cumulative 3-year survival rates were 96%, 89%, and 70% for the low, intermediate, and high-risk strata, respectively. We found no difference in outcomes at 1 year between risk groups. High-risk patients had an increased risk of death at 3 years using REVEAL 2.0 (HR 5.32, p < 0.001). However, while REVEAL 2.0 accurately discriminated high-risk patients, the hazard ratio was not statistically different between patients classified as intermediate-risk compared to low-risk.

Conclusion

REVEAL 2.0 accurately predicted 3-year survival in PH-LHD patients with high-risk features. However, the mortality risk between patients classified as intermediate-risk was not different from the low-risk stratum, suggesting inaccurate classification for this group of patients.

Application of REVEAL Lite 2 and COMPERA 2.0 risk scores to patients with pulmonary arterial hypertension switching to riociguat in the REPLACE study

In Riociguat rEplacing PDE5i therapy evaLuated Against Continued PDE5i thErapy (REPLACE) (NCT02891850), improvements in risk status were observed in patients with pulmonary arterial hypertension (PAH) at intermediate risk switching to riociguat versus continuing phosphodiesterase-5 inhibitors (PDE5i). This post hoc study applied the Registry to Evaluate Early and Long-Term PAH Disease Management (REVEAL) Lite 2 and Comparative Prospective Registry of Newly Initiated Therapies for Pulmonary (COMPERA) 2.0 risk-assessment tools to REPLACE to investigate the impact of baseline risk status on clinical improvement. The proportions of riociguat- and PDE5i-treated patients achieving the primary end-point at REVEAL Lite 2 low, intermediate, and high baseline risk reflected the overall population. Proportions of riociguat-treated patients achieving the primary end-point were comparable between the COMPERA 2.0 intermediate-low risk (39%) and intermediate-high risk (43%) groups. Our findings show that patients in REPLACE achieved clinical improvement by switching from PDE5i to riociguat across all COMPERA 2.0 and most REVEAL Lite 2 baseline risk strata.

Hemodynamic Response to Oral Vasodilator Therapy in Systemic Sclerosis-Related Pulmonary Hypertension

PURPOSE

Although classified as group 1 pulmonary arterial hypertension (PAH), patients with systemic sclerosis-related pulmonary hypertension (SSc-PH) experience poorer clinical response to PAH therapy and increased mortality compared to those with idiopathic PAH. Due to heterogeneity in phenotypes, identifying patients likely to respond to therapy is challenging. The goal of this study was to determine clinical factors associated with hemodynamic response, defined by a > 20% reduction in pulmonary vascular resistance on repeat right heart catheterization.

METHODS

We applied a time-to-event model using a retrospective cohort of 39 patients with precapillary SSc-PH, defined by a mean pulmonary artery pressure of ≥ 25 mmHg and pulmonary arterial wedge pressure (PAWP) ≤ 15 mmHg on right heart catheterization.

RESULTS

Patients with PAWP ≤ 8 mmHg were nearly fourfold more likely to achieve a hemodynamic response compared to those with PAWP > 8 mmHg (HR 3.88; 95% CI: 1.20, 12.57); each 1 mmHg increase in PAWP was associated with a decreased hazard for hemodynamic response (HR 0.84; 95% CI: 0.70, 1.00).

CONCLUSION

In patients with precapillary SSc-PH, PAWP was associated with time to hemodynamic response, suggesting the importance of subclinical cardiac disease in determining hemodynamic response to oral vasodilator therapy.

Pulmonary Hypertension in Connective Tissue Diseases Other than Systemic Sclerosis

Pulmonary hypertension (PH) is a known complication of certain connective tissue diseases (CTDs), with systemic sclerosis (SSc) being the most common in the Western world. However, PH in association with non-SSc CTD such as systemic lupus erythematous, mixed connective tissue disease, and primary Sjögren's syndrome constitutes a distinct subset of patients with inherently different epidemiologic profiles, pathophysiologic mechanisms, clinical features, therapeutic options, and prognostic implications. The purpose of this review is to inform a practical approach for clinicians evaluating patients with non-SSc CTD-associated PH.The development of PH in these patients involves a complex interplay between genetic factors, immune-mediated mechanisms, and endothelial cell dysfunction. Furthermore, the broad spectrum of CTD manifestations can contribute to the development of PH through various pathophysiologic mechanisms, including intrinsic pulmonary arteriolar vasculopathy (pulmonary arterial hypertension, Group 1 PH), left-heart disease (Group 2), chronic lung disease (Group 3), chronic pulmonary artery obstruction (Group 4), and unclear and/or multifactorial mechanisms (Group 5). The importance of diagnosing PH early in symptomatic patients with non-SSc CTD is highlighted, with a review of the relevant biomarkers, imaging, and diagnostic procedures required to establish a diagnosis.Therapeutic strategies for non-SSc PH associated with CTD are explored with an in-depth review of the medical, interventional, and surgical options available to these patients, emphasizing the CTD-specific considerations that guide treatment and aid in prognosis. By identifying gaps in the current literature, we offer insights into future research priorities that may prove valuable for patients with PH associated with non-SSc CTD.

Usefulness of risk assessment tools in predicting hemodynamic outcome after balloon pulmonary angioplasty: a comparative analysis

OBJECTIVES

Several parameters of widely used risk assessment tools for pulmonary arterial hypertension (PAH) have been linked to hemodynamic outcomes of balloon pulmonary angioplasty (BPA). Therefore, we aimed to determine whether these risk assessment tools could be used to predict hemodynamic outcomes following BPA.

METHODS

In this retrospective study, we included 139 patients with chronic thromboembolic pulmonary hypertension who had undergone BPA at Center for Pulmonary Vascular Diseases, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College (Beijing, China). We compared the accuracies of seven well-validated risk assessment tools for predicting hemodynamic outcomes following BPA. A favorable hemodynamic outcome was defined as a mean pulmonary arterial pressure < 30 mmHg at follow-up.

RESULTS

The baseline risk profiles varied significantly among the risk assessment tools. The US Registry to Evaluate Early and Long-Term PAH Disease Management risk scales and the French risk assessment tools rated most patients as high-risk, while the Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension (COMPERA) series and laboratory examination-based risk scales categorized most patients as having intermediate-risk profile. COMPERA 2.0 (4-strata) exhibited the highest predictive power among all risk stratifications. Noninvasive risk stratification (COMPERA 2.0 [3-strata]) showed a comparable predictive ability to that of invasive risk stratification (COMPERA 1.0) (area under the curve 0.649 vs. 0.648). Moreover, incorporating diffusing capacity of the lungs for carbon monoxide and tricuspid regurgitation velocity into COMPERA 2.0 (4-strata) further enhanced its predictive power (net reclassification index 0.153, 95% confidence interval 0.009-0.298, p = 0.038). Additionally, this refined COMPERA version had a high calibration accuracy (slope 0.96).

CONCLUSION

Although the risk strata distribution varied among different risk assessment tools, the proportion of patients achieving favorable hemodynamics decreased with the escalation of risk stratification in most models. The well-validated risk assessment tools for PAH could also predict hemodynamic outcomes following BPA, and the refined COMPERA 2.0 model exhibited the highest predictive ability among these. Applying risk assessment tools before BPA can facilitate early identification of patients in need of closer monitoring and more intensive interventions, contributing to a better prognosis after BPA.

Nitroprusside Combined with Leg Raise at the Time of Right Heart Catheterization to Differentiate Precapillary from Other Hemodynamic Forms of Pulmonary Hypertension: A Single-Center Pilot Study

Pulmonary hypertension (PH) can arise from several distinct disease processes, with a percentage presenting with combined pre- and postcapillary pulmonary hypertension (cpcPH). Patients with cpcPH are unsuitable candidates for PH-directed therapies due to elevated pulmonary capillary wedge pressures (PCWPs); however, the PCWP is dynamic and is affected by both preload and afterload. Many patients that are diagnosed with cpcPH are hypertensive at the time of right heart catheterization which has the potential to increase the PCWP and, therefore, mimic a more postcapillary-predominant phenotype. In this small pilot study, we examine the effect of nitroprusside combined with dynamic preload augmentation with a passive leg raise maneuver in hypertensive cpcPH patients at the time of right heart catheterization to identify a more precapillary-dominant PH phenotype. Patients that met the criteria of PCWP ≤ 15 mmHg with nitroprusside infusion and PCWP ≤ 18 mmHg with nitroprusside infusion and simultaneous leg raise were started on pulmonary vascular-targeted therapy. Long-term PH therapy was well tolerated, with increased six-minute walk distance, improved WHO functional class, decreased NT-proBNP, and improved REVEAL 2.0 Lite Risk Score in this precapillary-dominant PH phenotype. This small study highlights the importance of characterizing patient physiology beyond resting conditions at the time of right heart catheterization.

Assessing quality of life in pulmonary arterial hypertension: An independent prognostic marker

Pulmonary arterial hypertension (PAH, or PH Group 1), a disease of aberrant pulmonary vascular remodeling, causing progressive right heart failure (RHF) due to elevation of pulmonary vascular resistance (PVR). Patient mortality risk stratification guides choice and intensity of pharmacological intervention and is assessed by haemodynamics (especially PVR) as well as noninvasive tools including WHO functional class (FC), 6-min walk distance (6MWD), and NT-proBNP levels. Quality of life (QOL) assessment is acknowledged as a central aspect of patient-centered care, but our study sought to extend QOL's role as an additional noninvasive risk marker that could further refine risk stratification and hence therapeutic choices within a "treatment to target" paradigm (aiming to achieve low-risk status). This study found that QOL assessment using the PAH-SYMPACT© physical activity tool provided enhanced, independent mortality risk information, with one unit rise in this score associated with a 41% increase in likelihood risk (odds ratio 1.41, 95% confidence interval: 1.01-1.98 (p < 0.05)) of falling within intermediate versus low-group category. We therefore found further support for additional prognostic value being conferred by measurement of QOL as part of routine PAH evaluation, reinforcing its critical role.

Cardiac effort and 6-min walk distance correlate with stroke volume measured by cardiac magnetic resonance imaging

Right ventricular (RV) dysfunction in pulmonary arterial hypertension (PAH) is associated with poor outcomes. Cardiac magnetic resonance imaging (cMRI) is the gold standard for volumetric assessment, and few reports have correlated 6-min walk distance (6MWD) and cMRI parameters in PAH. Cardiac Effort, (the number of heart beats used during 6-min walk test)/(6MWD), incorporates physiologic changes into walk distance and has been associated with stroke volume (SV) measured by nuclear imaging and indirect Fick. Here, we aimed to interrogate the relationship of Cardiac Effort and 6MWD with SV measured by the gold standard, cMRI. This was a single-center, observational, prospective study in Group 1 PAH patients. Subjects completed 6-min walk with heart rate monitoring (Cardiac Effort) and cMRI within 24 h. cMRI was correlated to Cardiac Effort and 6MWD using Spearman Correlation Coefficient. Twenty-five participants with a wide range of RV function completed both cMRI and Cardiac Effort. There was a strong correlation between left ventricle SV index and both Cardiac Effort (r = -0.70, p = 0.0001) and 6MWD (r = 0.67, p = 0.0002). Cardiac Effort and 6MWD were statistically separated in patients at prognostically significant thresholds of left ventricle SV index (>31 ml/m2), RV Ejection Fraction (>35%), and SV/End Systolic Volume ( > 0.53). Cardiac Effort and 6MWD are noninvasive ways to gain insight into those with impaired SV. 6MWD may correlate better with SV than previously thought and heart rate monitoring provides physiologic context to the walk distance obtained.

Identifying consistent echocardiographic thresholds for risk stratification in pulmonary arterial hypertension

Several indices of right heart remodeling and function have been associated with survival in pulmonary arterial hypertension (PAH). Outcome analysis and physiological relationships between variables may help develop a consistent grading system. Patients with Group 1 PAH followed at Stanford Hospital who underwent right heart catheterization and echocardiography within 2 weeks were considered for inclusion. Echocardiographic variables included tricuspid annular plane systolic excursion (TAPSE), right ventricular (RV) fractional area change (RVFAC), free wall strain (RVFWS), RV dimensions, and right atrial volumes. The main outcome consisted of death or lung transplantation at 5 years. Mathematical relationships between variables were determined using weighted linear regression and severity thresholds for were calibrated to a 20% 1-year mortality risk. PAH patients (n = 223) had mean (SD) age of 48.1 (14.1) years, most were female (78%), with a mean pulmonary arterial pressure of 51.6 (13.8) mmHg and pulmonary vascular resistance index of 22.5(6.3) WU/m2. Measures of right heart size and function were strongly related to each other particularly RVFWS and RVFAC (R 2 = 0.82, p < 0.001), whereas the relationship between TAPSE and RVFWS was weaker (R 2 = 0.28, p < 0.001). Death or lung transplantation at 5 years occurred in 78 patients (35%). Guided by outcome analysis, we ascertained a uniform set of parameter thresholds for grading the severity of right heart adaptation in PAH. Using these quantitative thresholds, we, then, validated the recently reported REVEAL-echo score (AUC 0.68, p < 0.001). This study proposes a consistent echocardiographic grading system for right heart adaptation in PAH guided by outcome analysis.

Sendaway capillary NT-proBNP in pulmonary hypertension

BACKGROUND

N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a biomarker of cardiac ventricular wall stress that is incorporated into pulmonary hypertension (PH) risk stratification models. Sendaway sampling may enable patients to perform NT-proBNP tests remotely. This UK-wide study aimed to assess the agreement of sendaway NT-proBNP with standard venous NT-proBNP and to assess the effect of delayed processing.

METHODS

Reference venous NT-proBNP was collected from PH patients. Samples for capillary and venous sendaway tests were collected contemporaneously, mailed to a reference laboratory and processed at 3 and 7 days using a Roche Cobas e411 device. Differences in paired measurements were analysed with Passing-Bablok regression, percentage difference plots and the % difference in risk strata.

RESULTS

113 patients were included in the study. 13% of day 3 capillary samples were insufficient. Day 3 capillary samples were not equivalent to reference samples (Passing Bablok analysis slope of 0.91 (95% CI 0.88 to 0.93) and intercept of 6.0 (95% CI 0.2 to 15.9)). The relative median difference was -7% and there were acceptable limits of agreement. Day 3 capillary NT-proBNP accurately risk stratified patients in 93.5% of cases. By comparison, day 3 venous results accurately risk stratified patients in 90.1% of cases and were equivalent by Passing-Bablok regression. Delayed sampling of sendaway tests led to an unacceptable level of agreement and systematically underestimated NT-proBNP.

CONCLUSIONS

Sendaway NT-proBNP sampling may provide an objective measure of right ventricular strain for virtual PH clinics. Results must be interpreted with caution in cases of delayed sampling.

Comparison of Contemporary Risk Scores in All Groups of Pulmonary Hypertension: A Pulmonary Vascular Research Institute GoDeep Meta-Registry Analysis

BACKGROUND

Pulmonary hypertension (PH) is a heterogeneous disease with a poor prognosis. Accurate risk stratification is essential for guiding treatment decisions in pulmonary arterial hypertension (PAH). Although various risk models have been developed for PAH, their comparative prognostic potential requires further exploration. Additionally, the applicability of risk scores in PH groups beyond group 1 remains to be investigated.

RESEARCH QUESTION

Are risk scores originally developed for PAH predictive in PH groups 1 through 4?

STUDY DESIGN AND METHODS

We conducted a comprehensive analysis of outcomes among patients with incident PH enrolled in the multicenter worldwide Pulmonary Vascular Research Institute GoDeep meta-registry. Analyses were performed across PH groups 1 through 4 and further subgroups to evaluate the predictive value of PAH risk scores, including Registry to Evaluate Early and Long-Term PAH Disease Mangement (REVEAL) Lite 2, REVEAL 2.0, ESC/ERS 2022, Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension (COMPERA) 3-strata, and COMPERA 4-strata.

RESULTS

Eight thousand five hundred sixty-five patients were included in the study, of whom 3,537 patients were assigned to group 1 PH, whereas 1,807 patients, 1,635 patients, and 1,586 patients were assigned to group 2 PH, group 3 PH, and group 4 PH, respectively. Pulmonary hemodynamics were impaired with median mean pulmonary arterial pressure of 42 mm Hg (interquartile range, 33-52 mm Hg) and pulmonary vascular resistance of 7 Wood units (WU) (interquartile range, 4-11 WU). All risk scores were prognostic in the entire PH population and in each of the PH groups 1 through 4. The REVEAL scores, when used as continuous prediction models, demonstrated the highest statistical prognostic power and granularity; the COMPERA 4-strata risk score provided subdifferentiation of the intermediate-risk group. Similar results were obtained when separately analyzing various subgroups (PH subgroups 1.1, 1.4.1, and 1.4.4; PH subgroups 3.1 and 3.2; group 2 with isolated postcapillary PH vs combined precapillary and postcapillary PH; patients of all groups with concomitant cardiac comorbidities; and severe [> 5 WU] vs nonsevere PH).

INTERPRETATION

This comprehensive study with real-world data from 15 PH centers showed that PAH-designed risk scores possess predictive power in a large PH cohort, whether considered as common to the group or calculated separately for each PH group (1-4) and various subgroups.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT05329714; URL: www.

CLINICALTRIALS

gov.

Oral Treprostinil is Associated with Improved Survival in FREEDOM-EV and its Open-Label Extension

INTRODUCTION

In the event-driven FREEDOM-EV trial, oral treprostinil delayed clinical worsening in patients with pulmonary arterial hypertension (PAH). Open-label extension studies offer additional data about tolerability, efficacy, and survival, especially for those initially assigned placebo. The aim of the current study was to determine if oral treprostinil changed survival when considering the parent and extension study, if treprostinil provides functional benefits for participants initially assigned to placebo, and if the benefits observed for those treated with treprostinil were durable.

METHODS

Both active and placebo participants from FREEDOM-EV could enroll in the FREEDOM-EV open-label extension (OLE) study after experiencing an investigator-assessed clinical worsening event or after parent study closure. All participants in the OLE were offered open-label oral treprostinil. Previously assigned placebo participants titrated to maximally tolerated doses; previously assigned treprostinil participants continued dose titration. We repeated assessments including functional class and 6-min walk distance (6MWD) at 12-week intervals and measured N-terminal pro-brain natriuretic peptide (NT-proBNP) at week 48. Survival was estimated by Kaplan-Meier analysis, and we estimated hazard ratio (HR) using Cox proportional hazards.

RESULTS

Of 690 FREEDOM-EV participants, 470 enrolled in the OLE; vital status was available for 89% of initial Freedom-EV participants. When considering the combined parent and open-label data, initial assignment to oral treprostinil reduced mortality (HR 0.64, 95% confidence interval 0.46-0.91, p = 0.013); absolute risk reduction was 9%. Participants randomized to placebo who initiated oral treprostinil after clinical worsening and tolerated treatment through week 48 demonstrated favorable shifts in functional class (p < 0.0001), 6MWD improvements of + 84 m (p < 0.0001), and a reduction in NT-proBNP of - 778 pg/mL (p = 0.02), compared to OLE baseline. Modest trends toward benefit were measured for those initially assigned placebo who did not have clinical worsening, and 132/144 (92%) of treprostinil assigned participants without clinical worsening remained on drug at week 48 in the OLE study. Adverse events were consistent with FREEDOM-EV.

CONCLUSION

Initial treprostinil assignment improved survival in the entire data set; those who began treprostinil after a clinical worsening in the placebo arm and tolerated drug to week 48 enjoyed substantial functional gains.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT01560637.

The nitric oxide-soluble guanylate cyclase-cGMP pathway in pulmonary hypertension: from PDE5 to soluble guanylate cyclase

The nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) pathway plays a key role in the pathogenesis of pulmonary hypertension (PH). Targeted treatments include phosphodiesterase type 5 inhibitors (PDE5i) and sGC stimulators. The sGC stimulator riociguat is approved for the treatment of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). sGC stimulators have a dual mechanism of action, enhancing the sGC response to endogenous NO and directly stimulating sGC, independent of NO. This increase in cGMP production via a dual mechanism differs from PDE5i, which protects cGMP from degradation by PDE5, rather than increasing its production. sGC stimulators may therefore have the potential to increase cGMP levels under conditions of NO depletion that could limit the effectiveness of PDE5i. Such differences in mode of action between sGC stimulators and PDE5i could lead to differences in treatment efficacy between the classes. In addition to vascular effects, sGC stimulators have the potential to reduce inflammation, angiogenesis, fibrosis and right ventricular hypertrophy and remodelling. In this review we describe the evolution of treatments targeting the NO-sGC-cGMP pathway, with a focus on PH.

Pulmonary primary oxysterol and bile acid synthesis as a predictor of outcomes in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare and fatal vascular disease with heterogeneous clinical manifestations. To date, molecular determinants underlying the development of PAH and related outcomes remain poorly understood. Herein, we identify pulmonary primary oxysterol and bile acid synthesis (PPOBAS) as a previously unrecognized pathway central to PAH pathophysiology. Mass spectrometry analysis of 2,756 individuals across five independent studies revealed 51 distinct circulating metabolites that predicted PAH-related mortality and were enriched within the PPOBAS pathway. Across independent single-center PAH studies, PPOBAS pathway metabolites were also associated with multiple cardiopulmonary measures of PAH-specific pathophysiology. Furthermore, PPOBAS metabolites were found to be increased in human and rodent PAH lung tissue and specifically produced by pulmonary endothelial cells, consistent with pulmonary origin. Finally, a poly-metabolite risk score comprising 13 PPOBAS molecules was found to not only predict PAH-related mortality but also outperform current clinical risk scores. This work identifies PPOBAS as specifically altered within PAH and establishes needed prognostic biomarkers for guiding therapy in PAH.

Outcomes of listing for lung and heart-lung transplantation in pulmonary hypertension: comparative experience in France and the UK

Background

Lung or heart-lung transplantation (LT/HLT) for severe pulmonary hypertension (PH) as the primary disease indication carries a high risk of waiting list mortality and post-transplant complications. France and the UK both have coordinated PH patient services but with different referral pathways for accessing LT services.

Methods

We conducted a comparative analysis of adult PH patients listed for LT/HLT in the UK and France.

Results

We included 211 PH patients in France (2006-2018) and 170 in the UK (2010-2019). Cumulative incidence of transplant, delisting and waiting list death within 3 years were 81%, 4% and 11% in France versus 58%, 10% and 15% in the UK (p<0.001 for transplant and delisting; p=0.1 for death). Median non-priority waiting time was 45 days in France versus 165 days in the UK (p<0.001). High-priority listing occurred in 54% and 51% of transplanted patients respectively in France and the UK (p=0.8). Factors associated with achieving transplantation related to recipients' height, male sex, clinical severity and priority listing status. 1-year post-transplant survival was 78% in France and 72% in the UK (p= 0.04).

Conclusion

Access to transplantation for PH patients is better in France than in the UK where more patients were delisted due to clinical deterioration because of longer waiting time. High rates of priority listing occurred in both countries. Survival for those achieving transplantation was slightly better in France. Ensuring optimal outcomes after transplant listing for PH patients is challenging and may involve early listing of higher risk patients, increasing donor lung utilisation and improving allocation rules for these specific patients.

CT-derived lung vessel morphology correlates with prognostic markers in precapillary pulmonary hypertension

BACKGROUND

While computed tomography pulmonary angiography (CTPA) is an integral part of the work-up in patients with suspected pulmonary hypertension (PH), there is no established CTPA-derived prognostic marker. We aimed to assess whether quantitative readouts of lung vessel morphology correlate with established prognostic indicators in PH.

METHODS

We applied a fully-automatic in-house developed algorithm for segmentation of arteries and veins to determine lung vessel morphology in patients with precapillary PH who underwent right heart catheterization and CTPA between May 2016 and May 2019. Primary endpoint of this retrospective study was the calculation of receiver operating characteristics for identifying low and high mortality risk according to the 3-strata risk assessment model presented in the current guidelines.

RESULTS

We analyzed 73 patients, median age 65 years (interquartile range (IQR): 54-76), female/male ratio 35/38, median mean pulmonary arterial pressure 37 mm Hg (IQR: 30-46), and found significant correlations with important prognostic factors in pulmonary arterial hypertension. N-terminal pro-brain natriuretic peptide, cardiac index, mixed venous oxygen saturation, and 6-minute walking distance were correlated with the ratio of the number of arteries over veins with vessel diameters of 6-10 mm (Spearman correlation coefficients ρ = 0.64, p < 0.001; ρ = -0.60, p < 0.001; ρ = -0.47, p = 0.005; ρ = -0.45, p = 0.001, respectively). This ratio predicted a low- and high-risk score with an area under the curve of 0.73 (95% confidence interval (CI): 0.56-0.90) and 0.86 (95% CI: 0.74-0.97), respectively.

CONCLUSIONS

The ratio of the number of arteries over veins with diameters between 6 and 10 mm is significantly correlated with prognostic markers in pulmonary hypertension and predicts low and high mortality risk.

Evaluating the efficacy and safety of oral triple sequential combination therapy for treating patients with pulmonary arterial hypertension: A multicenter retrospective study

This study aimed to evaluate the effectiveness and safety of an oral sequential triple combination therapy with selexipag after dual combination therapy with endothelin receptor antagonist (ERA) and phosphodiesterase-5 inhibitor (PDE5I)/riociguat in pulmonary arterial hypertension (PAH) patients. A total of 192 PAH patients from 10 centers had received oral sequential selexipag therapy after being on dual-combination therapy with ERA and PDE5i/riociguat for a minimum of 3 months. Clinical data were collected at baseline and after 6 months of treatment. The study analyzed the event-free survival at 6 months and all-cause death over 2 years. At baseline, the distribution of patients among the risk groups was as follows: 22 in the low-risk group, 35 in the intermediate-low-risk group, 91 in the intermediate-high-risk group, and 44 in the high-risk group. After 6 months of treatment, the oral sequential triple combination therapy resulted in reduced NT-proBNP levels (media from 1604 to 678 pg/mL), a decline in the percentage of WHO-FC III/IV (from 79.2% to 60.4%), an increased in the 6MWD (from 325 ± 147 to 378 ± 143 m) and a rise in the percentage of patients with three low-risk criteria (from 5.7% to 13.5%). Among the low-risk group, there was an improvement in the right heart remodeling, marked by a decrease in right atrium area and eccentricity index. The intermediate-low-risk group exhibited significant enhancements in WHO-FC and tricuspid annular plane systolic excursion. For those in the intermediate-high and high-risk groups, there were marked improvements in activity tolerance, as reflected by WHO-FC and 6MWD. The event-free survival rate at 6 months stood at 88%. Over the long-term follow-up, the survival rates at 1 and 2 years were 86.5% and 86.0%, respectively. In conclusion, the oral sequential triple combination therapy enhanced both exercise capacity and cardiac remodeling across PAH patients of different risk stratifications.

CS1, a controlled-release formulation of valproic acid, for the treatment of patients with pulmonary arterial hypertension: Rationale and design of a Phase 2 clinical trial

Although rare, pulmonary arterial hypertension (PAH) is associated with substantial morbidity and a median survival of approximately 7 years, even with treatment. Current medical therapies have a primarily vasodilatory effect and do not modify the underlying pathology of the disease. CS1 is a novel oral, controlled-release formulation of valproic acid, which exhibits a multi-targeted mode of action (pulmonary pressure reduction, reversal of vascular remodeling, anti-inflammatory, anti-fibrotic, and anti-thrombotic) and therefore potential for disease modification and right ventricular modeling in patients with PAH. A Phase 1 study conducted in healthy volunteers indicated favorable safety and tolerability, with no increased risk of bleeding and significant reduction of plasminogen activator inhibitor 1. In an ongoing randomized Phase 2 clinical trial, three doses of open-label CS1 administered for 12 weeks is evaluating the use of multiple outcome measures. The primary endpoint is safety and tolerability, as measured by the occurrence of adverse events. Secondary outcome measures include the use of the CardioMEMS™ HF System, which provides a noninvasive method of monitoring pulmonary artery pressure, as well as cardiac magnetic resonance imaging and echocardiography. Other outcomes include changes in risk stratification (using the REVEAL 2.0 and REVEAL Lite 2 tools), patient reported outcomes, functional capacity, 6-min walk distance, actigraphy, and biomarkers. The pharmacokinetic profile of CS1 will also be evaluated. Overall, the novel design and unique, extensive clinical phenotyping of participants in this trial will provide ample evidence to inform the design of any future Phase 3 studies with CS1.

Outcomes and risk assessment in pulmonary veno-occlusive disease

Introduction

Pulmonary veno-occlusive disease (PVOD) is a rare and severe subtype of pulmonary arterial hypertension (PAH). Although European Society of Cardiology/European Respiratory Society (ESC/ERS) guidelines advise assessing PAH severity at baseline and during follow-up, no existing risk assessment methods have been validated for PVOD. This study aimed to identify prognostic factors, examine the impact of treatment strategies and evaluate risk assessment methods for PVOD patients.

Methods

The study analysed all incident PVOD patients included in the French Pulmonary Hypertension Registry between 2006 and 2021. Survival was assessed based on initial treatment strategy and risk status and compared to a matched (age, sex, pulmonary vascular resistance) PAH group. Six risk assessment methods (number of four low-risk and three noninvasive low-risk variables, ESC/ERS guidelines three-strata and four-strata models, REVEAL 2.0 and Lite 2) were applied at baseline and early follow-up, and their accuracy was compared using Harrell's c-statistic.

Results

Among the 327 included PVOD patients, survival rates at 1, 3 and 5 years were 86%, 50% and 27%, respectively. Multivariate analysis showed that only 6-min walk distance was associated with survival, with no significant difference based on initial treatment strategy. All six risk assessment methods could discriminate mortality risk, and the ESC/ERS four-strata model was the most accurate at both baseline and follow-up (C-index 0.64 and 0.74). PVOD survival rates were consistently lower than PAH when comparing baseline risk status using the ESC/ERS four-strata model.

Conclusion

PVOD is associated with poor outcomes, and initial treatment strategies do not significantly affect survival. Risk assessment methods can be useful in predicting survival for PVOD patients.

Simplified risk stratification based on cardiopulmonary exercise test: A Spanish two-center experience

A simplified 4-strata risk stratification approach based on three variables is widespread in pulmonary arterial hypertension (PAH) at follow-up. This study aimed to assess the impact of replacing the 6-min walk test (6MWT) with the peak 02 uptake evaluated by the cardiopulmonary exercise test (CPET) on risk stratification by this scale. We included 180 prevalent patients with PAH from two reference hospitals in Spain, followed up between 2006 and 2022. Patients were included if all the variables of interest were available within a 3-month period on the Spanish Registry of Pulmonary Arterial Hypertension (REHAP): functional class (FC); NT-proBNP; 6MWT; and CPET. The original 4-strata model (NT-proBNP, 6MWT, FC) identified most patients at low or intermediate-low risk (36.7% and 51.1%, respectively). Notably, the modified scale (NT-proBNP, CPET, FC) improved the identification of patients at intermediate-high risk up to 18.9%, and at high risk up to 1.1% in comparison with the previous 12.2% and 0.0% in the original scale. This new model increased the number of patients correctly classified into higher-risk strata (positive NRI of 0.06), as well as classified more patients without events in lower-risk strata (negative NRI of 0.04). The proposed score showed a slightly superior prognostic capacity compared with the original model (Harrel's C-index 0.717 vs. 0.709). Using O2 uptake instead of distance walked in the 6MWT improves the identification of high-risk patients using the 4-strata scale. This change could have relevant prognostic implications and lead to changes in the specific treatment of PAH.

Surgery and Anesthesia in Patients with Pulmonary Hypertension

Pulmonary hypertension is characterized by right ventricular impairment and a reduced ability to compensate for hemodynamic insults. Consequently, surgery can be challenging but is increasingly considered in view of available specific therapies and improved longer term survival. Optimal management requires a multidisciplinary patient-centered approach involving surgeons, anesthetists, pulmonary hypertension clinicians, and intensivists. The optimal pathway involves risk:benefit assessment for the proposed operation, optimization of pulmonary hypertension and any comorbidities, the appropriate anesthetic approach for the specific procedure and patient, and careful monitoring and management in the postoperative period. Where patients are carefully selected and meticulously managed, good outcomes can be achieved.

Regional Variation in Pulmonary Arterial Hypertension in the United States: The Pulmonary Hypertension Association Registry

Rationale: Pulmonary arterial hypertension (PAH) is a heterogeneous disease within a complex diagnostic and treatment environment. Other complex heart and lung diseases have substantial regional variation in characteristics and outcomes; however, this has not been previously described in PAH. Objectives: To identify baseline differences between U.S. census regions in the characteristics and outcomes for participants in the Pulmonary Hypertension Association Registry (PHAR). Methods: Adults with PAH were divided into regional groups (Northeast, South, Midwest, and West), and baseline differences between census regions were presented. Kaplan-Meier survival analyses and Cox proportional hazards were used to estimate the association between region and mortality in unadjusted and adjusted models. Results: Substantial differences by census regions were seen in age, race, ethnicity, marital status, employment, insurance payor breakdown, active smoking, and current alcohol use. Differences were also seen in PAH etiology and baseline 6-minute walk distance test results. Treatment characteristics varied by census region, and mortality appeared to be lower in PHAR participants in the West (hazard ratio, 0.60; 95% confidence interval, 0.43-0.83, P = 0.005). This difference was not readily explained by differences in demographic characteristics, PAH etiology, baseline severity, baseline medication regimen, or disease prevalence. Conclusions: The present study suggests significant regional variation among participants at accredited pulmonary vascular disease centers in multiple baseline characteristics and mortality. This variation may have implications for clinical research planning and represent an important focus for further study to better understand whether there are remediable care aspects that can be addressed in the pursuit of providing equitable care in the United States.

A Clinical Decision Tool for Risk Stratifying Patients with Systemic Sclerosis-Related Pulmonary Hypertension

We devised a scoring system to identify patients with systemic sclerosis (SSc) at risk for pulmonary hypertension (PH) and predict all-cause mortality. Using 7 variables obtained via pulmonary function testing, echocardiography, and computed tomographic chest imaging, we applied the score to a retrospective cohort of 117 patients with SSc. There were 60 (51.3%) who were diagnosed with PH by right heart catheterization. Using a scoring threshold ≥ 0, our decision tool predicted PH with a sensitivity, specificity, and accuracy of 0.87 (95% CI 0.75, 0.94), 0.74 (95% CI 0.60, 0.84), and 0.80 (95% CI 0.72, 0.87), respectively. When adjusted for age at PH diagnosis, sex, and receipt of pulmonary arterial vasodilators, each one-point score increase was associated with an adjusted HR of 1.19 (95% CI 1.05, 1.34) for all-cause mortality. With further validation in external cohorts, our simplified clinical decision tool may better streamline earlier detection of PH in SSc.

Do Patients With Low-Risk Pulmonary Arterial Hypertension Really Benefit From Upfront Combination Therapy?: Insight From the AMBITION Trial

BACKGROUND

Based on results of the Ambrisentan and Tadalafil in Patients with Pulmonary Arterial Hypertension (AMBITION) trial, upfront combination therapy is recommended for treatment-naive patients with low-risk pulmonary arterial hypertension (PAH). However, conflicting data exist whether adopting this treatment strategy in this risk group is beneficial or well tolerated.

RESEARCH QUESTION

Do patients with low-risk PAH really benefit from upfront combination therapy?

STUDY DESIGN AND METHODS

Using the data from the original AMBITION trial, patients with PAH were classified as low, intermediate, or high risk using the Registry to Evaluate Early and Long-term PAH Disease Management 2.0 (REVEAL 2.0) score and the Pulmonary Hypertension Outcomes and Risk Assessment (PHORA) tool. The primary end point was time to clinical worsening (including death, hospitalization for PAH worsening, and disease progression) censored at 1- and 3-year post-enrollment. Side effects that led to withdrawal of treatment were also considered.

RESULTS

Patients with low-risk PAH categorized by REVEAL 2.0 and PHORA did not see a statistically significant benefit of upfront combination therapy vs monotherapy for time to clinical worsening at 1 and 3 years' post-enrollment using Cox proportional analysis (3-year hazard ratio of 0.40 [95% CI, 0.15-1.06; P = .07] and 0.55 [95% CI, 0.26-1.18; P = .12] for REVEAL 2.0 and PHORA, respectively) or considering time to clinical worsening or side effects (3-year hazard ratio of 0.75 [95% CI, 0.39-1.47; P = .4] and 0.87 [95% CI, 0.49-1.54; P = .63] for REVEAL 2.0 and PHORA). Patients with low-risk PAH on upfront combination therapy experienced a higher but not significant incidence of side effects using REVEAL 2.0 and PHORA. In contrast, patients at intermediate or high risk saw a statistically significant benefit of upfront combination therapy considering each of the end points regardless of side effects.

INTERPRETATION

This analysis suggests that perhaps some patients with low-risk PAH should be further stratified using other modalities prior to committing to upfront combination therapy, especially when the occurrence of side effects is considered. Further prospective data are needed to validate this hypothesis prior to changes in current guideline directed therapy are contemplated.

Management of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare pulmonary vascular disease characterized by progressive pulmonary arterial remodeling, increased pulmonary vascular resistance, right ventricular dysfunction, and reduced survival. Effective therapies have been developed that target three pathobiologic pathways in PAH: nitric oxide, endothelin-1, and prostacyclin. Approved therapies for PAH include phosphodiesterase type-5 inhibitors, soluble guanylate cyclase stimulators, endothelin receptor antagonists, prostacyclin analogs, and prostacyclin receptor agonists. Management of PAH in the modern era incorporates multidimensional risk assessment to guide the use of these medications. For patients with PAH and without significant comorbidities, current guidelines recommend two oral medications (phosphodiesterase type-5 inhibitor and endothelin receptor antagonist) for low- and intermediate-risk patients, with triple therapy including a parenteral prostacyclin to be considered in those at high or intermediate-high risk. Combination therapy may be poorly tolerated and less effective in patients with PAH and cardiopulmonary comorbidities. Thus, a single-agent approach with individualized decisions to add-on other PAH therapies is recommended in older patients and those with significant comorbid conditions. Management of PAH is best performed in multidisciplinary teams located in experienced centers. Other core pillars of PAH management include supportive and adjunctive treatments including oxygen, diuretics, rehabilitation, and anticoagulation in certain patients. Patients with PAH who progress despite optimal treatment or who are refractory to best medical care should be referred for lung transplantation, if eligible. Despite considerable progress, PAH is often fatal and new therapies that reverse the disease and improve outcomes are desperately needed.

Restoration of right ventricular function in the treatment of pulmonary arterial hypertension

OBJECTIVE

A 45% threshold of right ventricular ejection fraction (RVEF) is proposed clinically relevant in patients with pulmonary arterial hypertension (PAH). We aim to determine treatment response, long-term right ventricular (RV) functional stability and prognosis of patients with PAH reaching or maintaining the RVEF 45% threshold.

METHODS

Incident, treatment-naive, adult PAH patients with cardiac magnetic resonance imaging at baseline and first follow-up were included (total N=127) and followed until date of censoring or death/lung transplantation. Patients were categorised into two groups based on 45% RVEF. Baseline predictors, treatment response and prognosis were assessed with logistic regression analyses, two-way analysis of variance and log-rank tests.

RESULTS

Patients were 50±17 years old, 73% female, of which N=75 reached or maintained the 45% RVEF threshold at follow-up (RVEF≥45%@FU), while N=52 patients did not (RVEF<45%@FU). RV end-diastolic volume and N-terminal pro-B-type natriuretic peptide at baseline were multivariable predictors of an RVEF ≥45% at follow-up. A 40% pulmonary vascular resistance (PVR) reduction resulted in greater improvement in RV function (ΔRVEF 17±11 vs. 5±8; pinteraction<0.001) compared to a PVR reduction <40%, but did not guarantee an RVEF ≥45%. Finally, the 45% RVEF threshold was associated with stable RV function during long-term follow-up and better survival (HR: 1.91 (95% CI: 1.11 to 3.27)). Patients failing to reach or maintain the 45% RVEF threshold at first follow-up mostly stayed below this threshold over the next consecutive visits.

CONCLUSION

After treatment initiation, 60% of patients with PAH reach or maintain the 45% RVEF threshold, which is associated with a long-term stable RV function and favourable prognosis.

Performance of the ESC/ERS 4-strata risk stratification model for pulmonary arterial hypertension with missing variables

The 2022 European Society of Cardiology (ESC)/European Respiratory Society (ERS) pulmonary hypertension (PH) guidelines recommend risk stratification to guide treatment decisions in patients with pulmonary arterial hypertension (PAH) [1, 2]. Risk, referring to the likelihood of death within 12 months, is estimated based on World Health Organization (WHO) functional class (FC), 6-min walk distance (6MWD), and serum levels of brain natriuretic peptide (BNP) or N-terminal pro-BNP (NT-proBNP), using prespecified thresholds. A 3-strata model (categorising risk as low, intermediate or high) is recommended at time of diagnosis, whereas a 4-strata model (categorising risk as low, intermediate–low, intermediate–high or high) is recommended during the course of the disease. The 4-strata model was developed from the Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension (COMPERA) and cross-validated by the French PH Registry [3, 4]. Both studies included patients when all three variables, i.e. WHO-FC, 6MWD and BNP/NT-proBNP were available at baseline. No formal assessment of the predictive value of the 4-strata model has been performed when one of these components was missing.

In patients with PAH, the ESC/ERS 4-strata risk model maintains some of its discriminative power when one of the three parameters (WHO-FC, 6MWD, and BNP/NT-proBNP) is missing, although with an increasing likelihood of overestimating risk https://bit.ly/46mz83d

Parenteral treprostinil induction for rapid attainment of therapeutic doses of oral treprostinil

RATIONALE

Oral treprostinil slows disease progression and improves exercise capacity in pulmonary arterial hypertension; however, titration can be prolonged. Published data suggests prostacyclin-naïve patients achieve total daily oral treprostinil doses of about 6 mg by Week 16, while those on prior parenteral treprostinil reach higher doses at the same timepoint.

OBJECTIVES

EXPEDITE (NCT03497689), a single-arm, multicenter study, assessed the efficacy of rapid parenteral treprostinil induction to quickly reach higher doses of oral treprostinil for the treatment of pulmonary arterial hypertension.

METHODS

Parenteral treprostinil was titrated for 2-8 weeks, followed by cross-titration of oral treprostinil. The primary endpoint was percentage of patients reaching ≥12 mg daily of oral treprostinil at Week 16. Secondary endpoints included clinical changes from baseline to Week 16.

RESULTS

Twenty-nine prostacyclin-naïve patients were included in efficacy analyses. At Week 16, the mean daily oral treprostinil dose was 16.4 mg; 79% of patients met the primary endpoint. From baseline to Week 16, median REVEAL Lite 2 score improved (decreased) from 6 to 3.5 (p = 0.0006). Statistically significant improvements were also seen in World Health Organization Functional Class, N-terminal-pro brain natriuretic peptide levels, 6-minute walk distance, right atrial area, Borg Dyspnea Score, and emPHasis-10 score. Favorable trends were seen in risk stratification, echocardiography parameters, disease symptoms, and treatment satisfaction.

CONCLUSION

Short-course parenteral treprostinil induction resulted in oral treprostinil doses over twice those reported in de novo initiations and may be a useful approach to quickly achieve the therapeutic benefits of oral treprostinil.

Pulmonary vasodilator therapies in pulmonary arterial hypertension associated with CHD: a systematic review and network meta-analysis

The optimal treatment strategy using pulmonary vasodilators in pulmonary arterial hypertension associated with CHD (PAH-CHD) remains controversial. We aimed to compare the efficacy and safety of pulmonary vasodilators in PAH-CHD. PubMed and EMBASE databases were searched through May 2022 and a network meta-analysis was conducted. The primary outcomes were mean difference of changes in 6-minute walk distance, NYHA functional class, and N-terminal pro-brain natriuretic peptide. The secondary outcomes included pulmonary vascular resistance, mean pulmonary arterial pressure, and resting oxygen saturation. We identified 14 studies, yielding 807 patients with PAH-CHD. Bosentan and sildenafil were associated with a significant increase in 6-minute walk distance from baseline compared with placebo (MD 48.92 m, 95% CI 0.32 to 97.55 and MD 59.70 m, 95% CI 0.88 to 118.53, respectively). Bosentan, sildenafil, and combination of bosentan and sildenafil were associated with significant improvement in NYHA functional class compared with placebo (MD -0.33, 95% CI -0.51 to -0.14, MD -0.58, 95% CI -0.75 to -0.22 and MD -0.62, 95% CI -0.92 to -0.31, respectively). Bosentan and sildenafil were also associated with significant improvements in secondary outcomes. These findings were largely confirmed in the subgroup analysis. Various adverse events were reported; however, serious adverse event rates were relatively low (4.8-8.7%), including right heart failure, acute kidney injury, respiratory failure, hypotension, and discontinuation of pulmonary vasodilators. In conclusion, bosentan and sildenafil were the most effective in improving prognostic risk factor such as 6-minute walk distance and NYHA class. Overall, pulmonary vasodilators were well tolerated in PAH-CHD.

Kynurenine pathway metabolism evolves with development of preclinical and scleroderma-associated pulmonary arterial hypertension

Understanding metabolic evolution underlying pulmonary arterial hypertension (PAH) development may clarify pathobiology and reveal disease-specific biomarkers. Patients with systemic sclerosis (SSc) are regularly surveilled for PAH, presenting an opportunity to examine metabolic change as disease develops in an at-risk cohort. We performed mass spectrometry-based metabolomics on longitudinal serum samples collected before and near SSc-PAH diagnosis, compared with time-matched SSc subjects without PAH, in a SSc surveillance cohort. We validated metabolic differences in a second cohort and determined metabolite-phenotype relationships. In parallel, we performed serial metabolomic and hemodynamic assessments as the disease developed in a preclinical model. For differentially expressed metabolites, we investigated corresponding gene expression in human and rodent PAH lungs. Kynurenine and its ratio to tryptophan (kyn/trp) increased over the surveillance period in patients with SSc who developed PAH. Higher kyn/trp measured two years before diagnostic right heart catheterization increased the odds of SSc-PAH diagnosis (OR 1.57, 95% CI 1.05-2.36, P = 0.028). The slope of kyn/trp rise during SSc surveillance predicted PAH development and mortality. In both clinical and experimental PAH, higher kynurenine pathway metabolites correlated with adverse pulmonary vascular and RV measurements. In human and rodent PAH lungs, expression of TDO2, which encodes tryptophan 2,3 dioxygenase (TDO), a protein that catalyzes tryptophan conversion to kynurenine, was significantly upregulated and tightly correlated with pulmonary hypertensive features. Upregulated kynurenine pathway metabolism occurs early in PAH, localizes to the lung, and may be modulated by TDO2. Kynurenine pathway metabolites may be candidate PAH biomarkers and TDO warrants exploration as a potential novel therapeutic target.NEW & NOTEWORTHY Our study shows an early increase in kynurenine pathway metabolism in at-risk subjects with systemic sclerosis who develop pulmonary arterial hypertension (PAH). We show that kynurenine pathway upregulation precedes clinical diagnosis and that this metabolic shift is associated with increased disease severity and shorter survival times. We also show that gene expression of TDO2, an enzyme that generates kynurenine from tryptophan, rises with PAH development.

A sham-controlled randomised trial of pulmonary artery denervation for Group 1 pulmonary arterial hypertension: one-year outcomes of the PADN-CFDA trial

BACKGROUND

Long-term clinical outcomes after pulmonary artery denervation (PADN) in patients with Group 1 pulmonary arterial hypertension (PAH) have not been reported.

AIMS

We aimed to investigate the effect of PADN on 1-year outcomes in patients with PAH.

METHODS

In the multicentre PADN-CFDA trial, 128 patients with Group 1 PAH were randomly assigned to PADN plus a phosphodiesterase-5 inhibitor (PDE-5i) versus a sham PADN procedure plus a PDE-5i. The principal endpoint of interest for the present study was clinical worsening at 1 year after randomisation, the composite of worsening of PAH (increase in WHO functional class, need for additional PAH treatments or PAH-related hospitalisation), atrial septostomy, listing for lung transplantation, or all-cause death.

RESULTS

One-year clinical follow-up was available in all patients. At 1 year, clinical worsening had occurred in 3 (4.8%) patients in the PADN plus PDE-5i group and in 15 patients (23.1%) in the sham plus PDE-5i group (adjusted hazard ratio: 0.17; 95% confidence interval [CI]: 0.05-0.60; p=0.006), driven by significantly increased rates of PAH-related hospitalisations, worsening functional class and the requirement for additional PAH treatments in the sham group. Results were consistent in high-risk, intermediate-risk and low-risk patients (pinteraction=0.186). Patients treated with PADN plus PDE-5i had an improvement in the between-group change in the six-minute walking distance (6MWD) from baseline to 1 year of 81.2 m (95% CI: 50.3-112.2; p<0.001) compared with PDE-5i treatment alone.

CONCLUSIONS

In this multicentre sham-controlled randomised trial, PADN treatment for Group 1 PAH significantly reduced clinical worsening and improved the 6MWD during 1-year follow-up in patients treated with a PDE-5i.

Lung Transplantation for Pulmonary Arterial Hypertension

TOPIC IMPORTANCE

Even though patients with pulmonary arterial hypertension have multiple therapeutic options, the disease can be refractory despite appropriate management. In patients with end-stage pulmonary arterial hypertension, lung transplantation has the potential both to extend survival and improve health-related quality of life. Pulmonary arterial hypertension is the only major diagnostic indication for transplantation that is not a parenchymal pulmonary process, and thus the care of these patients is unique.

REVIEW FINDINGS

This review focuses on the complexities of lung transplantation for patients with pulmonary arterial hypertension, presents the updated referral and listing criteria, and discusses the inequities in the organ allocation process that impact this disease group and the strategies to optimize outcomes for patients with pulmonary arterial hypertension who require lung transplantation.

SUMMARY

Lung transplantation is an effective and lifesaving therapy for patients with end-stage lung disease. Sadly, patients with pulmonary arterial hypertension face many challenges as it relates to transplantation including higher perioperative risks, inequities in the allocation system, and less favorable long-term outcomes. This review covers the complexities of transplantation in patients with pulmonary vascular disease.

Real-world evidence to advance knowledge in pulmonary hypertension: Status, challenges, and opportunities. A consensus statement from the Pulmonary Vascular Research Institute's Innovative Drug Development Initiative's Real-world Evidence Working Group

This manuscript on real-world evidence (RWE) in pulmonary hypertension (PH) incorporates the broad experience of members of the Pulmonary Vascular Research Institute's Innovative Drug Development Initiative Real-World Evidence Working Group. We aim to strengthen the research community's understanding of RWE in PH to facilitate clinical research advances and ultimately improve patient care. Herein, we review real-world data (RWD) sources, discuss challenges and opportunities when using RWD sources to study PH populations, and identify resources needed to support the generation of meaningful RWE for the global PH community.

Safety and efficacy of transitioning from selexipag to oral treprostinil in pulmonary arterial hypertension: Findings from the ADAPT registry

PURPOSE

Oral treprostinil and selexipag are drugs targeting the prostacyclin pathway and are approved for treatment of pulmonary arterial hypertension (PAH). In the setting of unsatisfactory clinical response or tolerability issues while on selexipag, there is little data on clinical benefit, safety, or strategies on transitioning to oral treprostinil. Using prospective data from the ADAPT registry, we aimed to evaluate clinical outcomes, safety, and transition strategies in ten patients with PAH transitioning from selexipag to oral treprostinil.

METHODS

ADAPT was a prospective, real-world, multicenter, United States-based registry of patients with PAH newly started on oral treprostinil, with a cohort of patients (n = 10) transitioning from selexipag to oral treprostinil. PAH variables of interest were collected from standard-of-care clinic visits. Clinical improvement was defined by modified REPLACE criterion, and risk was assessed by REVEAL Lite 2 from baseline to last follow-up. Real world transition strategies were recorded. Healthcare utilization or worsening PAH was evaluated within 30 days of transitions.

RESULTS

Seven patients transitioned due to worsening PAH or lack of efficacy on selexipag, and three patients transitioned due to tolerability issues. Based on the modified REPLACE criterion, five patients demonstrated clinical improvement after transition from selexipag to oral treprostinil. Using REVEAL Lite 2 to assess risk, three patients improved and five patients maintained risk category from baseline to last follow-up. All transitions occurred in an outpatient setting either as abrupt stop/start or cross-titration, without parenteral treprostinil bridging.

CONCLUSION

Transition from selexipag to oral treprostinil was safe, performed without parenteral prostacyclin bridging, and resulted in clinical and categorical risk improvements in some patients.

Is low-risk status a surrogate outcome in pulmonary arterial hypertension? An analysis of three randomised trials

BACKGROUND

Targeting short-term improvements in multicomponent risk scores for mortality in patients with pulmonary arterial hypertension (PAH) could result in improved long-term outcomes. We aimed to determine whether PAH risk scores were adequate surrogates for clinical worsening or mortality outcomes in PAH randomised clinical trials (RCTs).

METHODS

We performed an individual participant data meta-analysis of RCTs selected from PAH trials provided by the US Food and Drug Administration (FDA). We calculated predicted risk using the COMPERA, COMPERA 2.0, non-invasive FPHR, REVEAL 2.0, and REVEAL Lite 2 risk scores. The primary outcome of interest was time to clinical worsening, a composite endpoint composed of any of the following events: all-cause death, hospitalisation for worsening PAH, lung transplantation, atrial septostomy, discontinuation of study treatment (or study withdrawal) for worsening PAH, initiation of parenteral prostacyclin analogue therapy, or decrease of at least 15% in 6-min walk distance from baseline, combined with either worsening of WHO functional class from baseline or the addition of an approved PAH treatment. The secondary outcome of interest was time to all-cause mortality. We assessed the surrogacy of these risk scores, parameterised as attainment of low-risk status by 16 weeks, for improvement in long-term clinical worsening and survival using mediation and meta-analysis frameworks.

FINDINGS

Of 28 trials received from the FDA, three RCTs (AMBITION, GRIPHON, and SERAPHIN; n=2508) had the data necessary to assess long-term surrogacy. The mean age was 49 years (SD 16), 1956 (78%) participants were women, 1704 (68%) were classified as White, and 280 (11%) were Hispanic or Latino. 1388 (55%) of 2503 participants with available data had idiopathic PAH and 776 (31%) of 2503 had PAH associated with connective tissue disease. In a mediation analysis, the proportions of treatment effects explained by attainment of low-risk status ranged only from 7% to 13%. In a meta-analysis of trial-regions, the treatment effects on low-risk status were not predictive of the treatment effects on time to clinical worsening (R2 values 0·01-0·19) nor the treatment effects on time to all-cause mortality (R2 values 0-0·2). A leave-one-out analysis suggested that the use of these risk scores as surrogates might lead to biased inferences regarding the effect of therapies on clinical outcomes in PAH RCTs. Results were similar when using absolute risk scores at 16 weeks as the potential surrogates.

INTERPRETATION

Multicomponent risk scores have utility for the prediction of outcomes in patients with PAH. Clinical surrogacy for long-term outcomes cannot be inferred from observational studies of outcomes. Our analyses of three PAH trials with long-term follow-up suggest that further study is necessary before using these or other scores as surrogate outcomes in PAH RCTs or clinical care.

FUNDING

Cardiovascular Medical Research and Education Fund, US National Institutes of Health.

Heart Rate Response Predicts 6-Minutes Walking Distance in Pulmonary Arterial Hypertension

Because the 6-minute walking test (6MWT) is a self-paced submaximal test, the 6-minute walking distance (6MWD) is substantially influenced by individual effort level and physical condition, which is difficult to quantify. We aimed to explore the optimal indicator reflecting the perceived effort level during 6MWT. We prospectively enrolled 76 patients with pulmonary arterial hypertension and 152 healthy participants; they performed 2 6MWTs at 2 different speeds: (1) at leisurely speed, as performed in daily life without extra effort (leisure 6MWT) and (2) an increased walking speed, walking as the guideline indicated (standard 6MWT). The factors associated with 6MWD during standard 6MWT were investigated using a multiple linear regression analysis. The heart rate (HR) and Borg score increased and oxygen saturation (SpO2) decreased after walking in 2 6MWTs in both groups (all p <0.001). The ratio of difference in HR before and after each test (ΔHR) to HR before walking (HRat rest) and the difference in SpO2 (ΔSpO2) and Borg (ΔBorg) before and after each test were all significantly higher in both groups after standard 6MWT than after leisure 6MWT (all p <0.001). Multiple linear regression analysis revealed that ΔHR/HRat rest was an independent predictor of 6MWD during standard 6MWT in both groups (both p <0.001, adjusted R2 = 0.737 and 0.49, respectively). 6MWD and ΔHR/HRat rest were significantly lower in patients than in healthy participants (both p <0.001) and in patients with cardiac functional class III than in patients with class I/II (both p <0.001). In conclusion, ΔHR/HRat rest is a good reflector of combined physical and effort factors. HR response should be incorporated into 6MWD to better assess a participant's exercise capacity.

Potential Roles of Metals in the Pathogenesis of Pulmonary and Systemic Hypertension

Pulmonary and systemic hypertension (PH, SH) are characterized by vasoconstriction and vascular remodeling resulting in increased vascular resistance and pulmonary/aortic artery pressures. The chronic stress leads to inflammation, oxidative stress, and infiltration by immune cells. Roles of metals in these diseases, particularly PH are largely unknown. This review first discusses the pathophysiology of PH including vascular oxidative stress, inflammation, and remodeling in PH; mitochondrial dysfunction and metabolic changes in PH; ion channel and its alterations in the pathogenesis of PH as well as PH-associated right ventricular (RV) remodeling and dysfunctions. This review then summarizes metal general features and essentiality for the cardiovascular system and effects of metals on systemic blood pressure. Lastly, this review explores non-essential and essential metals and potential roles of their dyshomeostasis in PH and RV dysfunction. Although it remains early to conclude the role of metals in the pathogenesis of PH, emerging direct and indirect evidence implicates the possible contributions of metal-mediated toxicities in the development of PH. Future research should focus on comprehensive clinical metallomics study in PH patients; mechanistic evaluations to elucidate roles of various metals in PH animal models; and novel therapy clinical trials targeting metals. These important discoveries will significantly advance our understandings of this rare yet fatal disease, PH.