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 REVEAL Lite 2, REVEAL 2.0, ESC/ERS 2022, 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 (33-52 mm Hg) and pulmonary vascular resistance of 7 WU (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.

Macitentan in Pulmonary Arterial Hypertension Associated with Connective Tissue Disease (CTD-PAH): Real-World Evidence from the Combined OPUS/OrPHeUS Dataset

INTRODUCTION

Data on real-world clinical practice and outcomes of patients with pulmonary arterial hypertension associated with connective tissue disease (CTD-PAH) are scarce. The OPUS/OrPHeUS studies enrolled patients newly initiating macitentan, including those with CTD-PAH. This analysis describes patient characteristics, treatment patterns, outcomes, and safety profiles of patients with CTD-PAH newly initiating macitentan in the US using the OPUS/OrPHeUS combined dataset.

METHODS

OPUS was a prospective, US, multicenter, long-term, observational drug registry (April 2014-June 2020). OrPHeUS was a retrospective, US, multicenter medical chart review (October 2013-March 2017). The characteristics, treatment patterns, safety, and outcomes during macitentan treatment of patients with CTD-PAH and its subgroups systemic sclerosis (SSc-PAH), systemic lupus erythematosus (SLE-PAH), and mixed CTD (MCTD-PAH) were descriptively compared to patients with idiopathic/heritable PAH (I/HPAH).

RESULTS

The combined OPUS/OrPHeUS population included 2498 patients with I/HPAH and 1192 patients with CTD-PAH (708 SSc-PAH; 159 SLE-PAH; 124 MCTD-PAH, and 201 other CTD-PAH etiologies). At macitentan initiation for patients with I/HPAH and CTD-PAH, respectively: 61.2 and 69.3% were in World Health Organization functional class (WHO FC) III/IV; median 6-min walk distance was 289 and 279 m; and 58.1 and 65.2% received macitentan as combination therapy. During follow-up, for patients with I/HPAH and CTD-PAH, respectively: median duration of macitentan exposure observed was 14.0 and 15.8 months; 79.0 and 83.0% experienced an adverse event; Kaplan-Meier estimates (95% confidence limits [CL]) of patients free from all-cause hospitalization at 1 year were 60.3% (58.1, 62.4) and 59.3% (56.1, 62.3); and Kaplan-Meier estimates (95% CL) of survival at 1 year were 90.5% (89.1, 91.7) and 90.6% (88.6, 92.3).

CONCLUSIONS

Macitentan was used in clinical practice in patients with CTD-PAH and its subgroups, including as combination therapy. The safety and tolerability profile of macitentan in patients with CTD-PAH was comparable to that of patients with I/HPAH.

TRIAL REGISTRATION

OPsumit® Users Registry (OPUS): NCT02126943; Opsumit® Historical Users cohort (OrPHeUS): NCT03197688; www.

CLINICALTRIALS

gov Graphical abstract available for this article.

Single-Cell Imaging Maps Inflammatory Cell Subsets to Pulmonary Arterial Hypertension Vasculopathy

Rationale: Unraveling immune-driven vascular pathology in pulmonary arterial hypertension (PAH) requires a comprehensive understanding of the immune cell landscape. Although patients with hereditary (H)PAH and bone morphogenetic protein receptor type 2 (BMPR2) mutations have more severe pulmonary vascular pathology, it is not known whether this is related to specific immune cell subsets. Objectives: This study aims to elucidate immune-driven vascular pathology by identifying immune cell subtypes linked to severity of pulmonary arterial lesions in PAH. Methods: We used cutting-edge multiplexed ion beam imaging by time of flight to compare pulmonary arteries (PAs) and adjacent tissue in PAH lungs (idiopathic [I]PAH and HPAH) with unused donor lungs, as controls. Measurements and Main Results: We quantified immune cells' proximity and abundance, focusing on those features linked to vascular pathology, and evaluated their impact on pulmonary arterial smooth muscle cells (SMCs) and endothelial cells. Distinct immune infiltration patterns emerged between PAH subtypes, with intramural involvement independently linked to PA occlusive changes. Notably, we identified monocyte-derived dendritic cells within PA subendothelial and adventitial regions, influencing vascular remodeling by promoting SMC proliferation and suppressing endothelial gene expression across PAH subtypes. In patients with HPAH, pronounced immune dysregulation encircled PA walls, characterized by heightened perivascular inflammation involving T cell immunoglobulin and mucin domain-3 (TIM-3)+ T cells. This correlated with an expanded DC subset expressing indoleamine 2,3-dioxygenase 1, TIM-3, and SAM and HD domain-containing deoxynucleoside triphosphate triphosphohydrolase 1, alongside increased neutrophils, SMCs, and alpha-smooth muscle actin (ACTA2)+ endothelial cells, reinforcing the heightened severity of pulmonary vascular lesions. Conclusions: This study presents the first architectural map of PAH lungs, connecting immune subsets not only with specific PA lesions but also with heightened severity in HPAH compared with IPAH. Our findings emphasize the therapeutic potential of targeting monocyte-derived dendritic cells, neutrophils, cellular interactions, and immune responses to alleviate severe vascular pathology in IPAH and HPAH.

Clinical evaluation of code-based algorithms to identify patients with pulmonary arterial hypertension in healthcare databases

Pulmonary arterial hypertension (PAH) is a rare subgroup of pulmonary hypertension (PH). Claims and administrative databases can be particularly important for research in rare diseases; however, there is a lack of validated algorithms to identify PAH patients using administrative codes. We aimed to measure the accuracy of code-based PAH algorithms against the true clinical diagnosis by right heart catheterization (RHC). This study evaluated algorithms in patients who were recorded in two linkable data assets: the Stanford Healthcare administrative electronic health record database and the Stanford Vera Moulton Wall Center clinical PH database (which records each patient's RHC diagnosis). We assessed the sensitivity and specificity achieved by 16 algorithms (six published). In total, 720 PH patients with linked data available were included and 558 (78%) of these were PAH patients. Algorithms consisting solely of a P(A)H-specific diagnostic code classed all or almost all PH patients as PAH (sensitivity >97%, specificity <12%) while multicomponent algorithms with well-defined temporal sequences of procedure, diagnosis and treatment codes achieved a better balance of sensitivity and specificity. Specificity increased and sensitivity decreased with increasing algorithm complexity. The best-performing algorithms, in terms of fewest misclassified patients, included multiple components (e.g., PH diagnosis, PAH treatment, continuous enrollment for ≥6 months before and ≥12 months following index date) and achieved sensitivities and specificities of around 95% and 38%, respectively. Our findings help researchers tailor their choice and design of code-based PAH algorithms to their research question and demonstrate the importance of including well-defined temporal components in the algorithms.

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.

Evaluation of Acebilustat, a Selective Inhibitor of Leukotriene B4 Biosynthesis, for Treatment of Outpatients With Mild-Moderate Coronavirus Disease 2019: A Randomized, Double-Blind, Placebo-Controlled Phase 2 Trial

BACKGROUND

The vast majority of coronavirus disease 2019 (COVID-19) disease occurs in outpatients where treatment is limited to antivirals for high-risk subgroups. Acebilustat, a leukotriene B4 inhibitor, has potential to reduce inflammation and symptom duration.

METHODS

In a single-center trial spanning Delta and Omicron variants, outpatients were randomized to 100 mg/d of oral acebilustat or placebo for 28 days. Patients reported daily symptoms via electronic query through day 28 with phone follow-up on day 120 and collected nasal swab samples on days 1-10. The primary outcome was sustained symptom resolution to day 28. Secondary 28-day outcomes included time to first symptom resolution, area under the curve (AUC) for longitudinal daily symptom scores, duration of viral shedding through day 10, and symptoms on day 120.

RESULTS

Sixty participants were randomized to each study arm. At enrollment, the median duration was 4 days (interquartile range, 3-5 days), and the median number of symptoms was 9 (7-11). Most patients (90%) were vaccinated, with 73% having neutralizing antibodies. A minority of participants (44%; 35% in the acebilustat arm and 53% in placebo) had sustained symptom resolution at day 28 (hazard ratio, 0.6 [95% confidence interval, .34-1.04]; P = .07 favoring placebo). There was no difference in the mean AUC for symptom scores over 28 days (difference in mean AUC, 9.4 [95% confidence interval, -42.1 to 60.9]; P = .72). Acebilustat did not affect viral shedding or symptoms at day 120.

CONCLUSIONS

Sustained symptoms through day 28 were common in this low-risk population. Despite this, leukotriene B4 antagonism with acebilustat did not shorten symptom duration in outpatients with COVID-19. Clinical Trials Registration. NCT04662060.

Pulmonary Vein Sign on Computed Tomography Pulmonary Angiography in Proximal and Distal Chronic Thromboembolic Pulmonary Hypertension With Hemodynamic Correlation

BACKGROUND

Pulmonary vein sign (PVS) indicates abnormal pulmonary venous flow on computed tomography pulmonary angiography (CTPA) is a frequent finding in proximal chronic thromboembolic pulmonary hypertension (CTEPH). PVS's occurrence in distal CTEPH and correlation to disease severity is unknown. Using right heart catheterization data, we evaluated the relationship between PVS and CTEPH disease distribution and severity.

MATERIALS AND METHOD

A total of 93 consecutive CTEPH cases with both CTPA and right heart catheterization were identified in this retrospective multi-institutional study. After excluding 17 cases with suboptimal CTPA, there were 52 proximal and 24 distal CTEPH cases. Blood flow in the major pulmonary veins was graded qualitatively. Subgroup analysis of PVS was performed in 38 proximal CTEPH cases before and after pulmonary endarterectomy.

RESULTS

PVS was more frequent in proximal (79%) than distal CTEPH (29%) ( P <0.001). No significant difference was noted in invasive mean pulmonary artery pressure (46±11 and 41±12 mm Hg) or pulmonary vascular resistance (9.4±4.5 and 8.4±4.8 WU) between the 2 groups. In the subgroup analysis, PVS was present in 29/38 patients (76%) before surgery. Postoperatively, 33/38 cases (87%, P <0.001) had normal venous flow (mean pulmonary artery pressure 46±11 and 25; pulmonary vascular resistance 9.2±4.3 and 2.6 WU preop and postop, respectively).

CONCLUSION

PVS is a common feature in proximal but infrequent findings in distal CTEPH. PVS does not correlate with hemodynamic severity. PVS resolution was seen in the majority of patients following successful endarterectomy.

Minimal Clinically Important Difference in the 6-minute-walk Distance for Patients with Pulmonary Arterial Hypertension

Rationale: The 6-minute-walk distance (6MWD) is an important clinical and research metric in pulmonary arterial hypertension (PAH); however, there is no consensus about what minimal change in 6MWD is clinically significant. Objectives: We aimed to determine the minimal clinically important difference in the 6MWD. Methods: We performed a meta-analysis using individual participant data from eight randomized clinical trials of therapy for PAH submitted to the U.S. Food and Drug Administration to derive minimal clinically important differences in the 6MWD. The estimates were externally validated using the Pulmonary Hypertension Association Registry. We anchored the change in 6MWD to the change in the Medical Outcomes Survey Short Form physical component score. Measurements and Main Results: The derivation (clinical trial) and validation (Pulmonary Hypertension Association Registry) samples were comprised of 2,404 and 537 adult patients with PAH, respectively. The mean ± standard deviation age of the derivation sample was 50.5 ± 15.2 years, and 1,849 (77%) were female, similar to the validation sample. The minimal clinically important difference in the derivation sample was 33 meters (95% confidence interval, 27-38), which was almost identical to that in the validation sample (36 m [95% confidence interval, 29-43]). The minimal clinically important difference did not differ by age, sex, race, pulmonary hypertension etiology, body mass index, use of background therapy, or World Health Organization functional class. Conclusions: We estimated a 6MWD minimal clinically important difference of approximately 33 meters for adults with PAH. Our findings can be applied to the design of clinical trials of therapies for PAH.

Novel left ventricular mechanical index in pulmonary arterial hypertension

Ventricular interdependence plays an important role in pulmonary arterial hypertension (PAH). It can decrease left ventricular (LV) longitudinal strain (LVLS) and lead to a leftward displacement ("transverse shortening") of the interventricular septum (sTS). For this study, we hypothesized the ratio of LVLS/sTS would be a sensitive marker of systolic ventricular interactions in PAH. In a cross-sectional cohort of patients with PAH (n = 57) and matched controls (n = 57), we quantified LVLS and septal TS in the amplitude and time domain. We then characterized LV phenotypes using upset plots, ventricular interactions using network analysis, and longitudinal analysis in a representative cohort of 45 patients. We also measured LV metrics in mice subjected to pulmonary arterial banding (PAB) using a 7 T magnetic resonance imaging at baseline, Week 1, and Week 7 post-PAB (N = 9). Patients with PAH had significantly reduced absolute LVLS (15.4 ± 3.4 vs. 20.1 ± 2.3%, p < 0.0001), higher sTS (53.0 ± 12.2 vs. 28.0 ± 6.2%, p < 0.0001) and lower LVLS/sTS (0.30 ± 0.09 vs. 0.75 ± 0.16, p < 0.0001) compared to controls. Reduced LVLS/sTS was observed in 89.5% of patients, while diastolic dysfunction, impaired LVLS (<16%), and LV atrophy were observed in 73.7%, 52.6%, and 15.8%, respectively. In the longitudinal cohort, changes in LVLS/sTS were closely associated with changes in N-terminal pro B-type natriuretic peptide (r = 0.73, p < 0.0001) as well as survival. Mice subjected to PAB showed significant RV systolic dysfunction and decreased LVLS/sTS compared to sham animals. We conclude that in PAH, LVLV/sTS is a simple ratio that can reflect ventricular systolic interactions.

Computational platform for doctor-artificial intelligence cooperation in pulmonary arterial hypertension prognostication: a pilot study

Background

Pulmonary arterial hypertension (PAH) is a heterogeneous and complex pulmonary vascular disease associated with substantial morbidity. Machine-learning algorithms (used in many PAH risk calculators) can combine established parameters with thousands of circulating biomarkers to optimise PAH prognostication, but these approaches do not offer the clinician insight into what parameters drove the prognosis. The approach proposed in this study diverges from other contemporary phenotyping methods by identifying patient-specific parameters driving clinical risk.

Methods

We trained a random forest algorithm to predict 4-year survival risk in a cohort of 167 adult PAH patients evaluated at Stanford University, with 20% withheld for (internal) validation. Another cohort of 38 patients from Sheffield University were used as a secondary (external) validation. Shapley values, borrowed from game theory, were computed to rank the input parameters based on their importance to the predicted risk score for the entire trained random forest model (global importance) and for an individual patient (local importance).

Results

Between the internal and external validation cohorts, the random forest model predicted 4-year risk of death/transplant with sensitivity and specificity of 71.0-100% and 81.0-89.0%, respectively. The model reinforced the importance of established prognostic markers, but also identified novel inflammatory biomarkers that predict risk in some PAH patients.

Conclusion

These results stress the need for advancing individualised phenotyping strategies that integrate clinical and biochemical data with outcome. The computational platform presented in this study offers a critical step towards personalised medicine in which a clinician can interpret an algorithm's assessment of an individual patient.

Imaging the right atrium in pulmonary hypertension: A systematic review and meta-analysis

BACKGROUND

Right atrial (RA) imaging has emerged as a promising tool for the evaluation of patients with pulmonary hypertension (PH), albeit without systematic validation.

METHODS

PubMed, Web of Science and the Cochrane library were searched for studies investigating the prognostic value of RA imaging assessment in patients with PH from 2000 to June 2021 (PROSPERO Identifier: CRD42020212850). An inverse variance-weighted meta-analysis of univariable hazard ratios (HRs) was performed using a random effects model.

RESULTS

Thirty-five studies were included (3,476 patients with PH; 74% female, 86% pulmonary arterial hypertension). Risk of bias was low/moderate (Quality of Prognosis Studies checklist). RA area (HR 1.06; 95% confidence interval [CI] 1.04-1.08), RA indexed area (HR 1.09; 95% CI 1.04-1.14), RA peak longitudinal strain (PLS; HR 0.94; 95% CI 0.91-0.97) and RA total emptying fraction (HR 0.96; 95% CI 0.94-0.98) were significantly associated with combined end-points including death, clinical worsening and/or lung transplantation; RA volume and volume index showed marginal significant associations. RA area (HR 1.06; 95% CI 1.04-1.07), RA indexed area (HR 1.12; 95% CI 1.07-1.17) and RA PLS (HR 0.98; 95% CI 0.97-0.99) showed significant associations with mortality; RA total emptying fraction showed a marginal association.

CONCLUSIONS

Imaging-based RA assessment qualifies as a relevant prognostic marker in PH. RA area reliably predicts composite end-points and mortality, which underscores its clinical utility. RA PLS emerged as a promising imaging measure, but is currently limited by the number of studies and different acquisition methods.

Endogenous Retroviral Elements Generate Pathologic Neutrophils in Pulmonary Arterial Hypertension

Rationale: The role of neutrophils and their extracellular vesicles (EVs) in the pathogenesis of pulmonary arterial hypertension is unclear. Objectives: To relate functional abnormalities in pulmonary arterial hypertension neutrophils and their EVs to mechanisms uncovered by proteomic and transcriptomic profiling. Methods: Production of elastase, release of extracellular traps, adhesion, and migration were assessed in neutrophils from patients with pulmonary arterial hypertension and control subjects. Proteomic analyses were applied to explain functional perturbations, and transcriptomic data were used to find underlying mechanisms. CD66b-specific neutrophil EVs were isolated from plasma of patients with pulmonary arterial hypertension, and we determined whether they produce pulmonary hypertension in mice. Measurements and Main Results: Neutrophils from patients with pulmonary arterial hypertension produce and release increased neutrophil elastase, associated with enhanced extracellular traps. They exhibit reduced migration and increased adhesion attributed to elevated β1-integrin and vinculin identified by proteomic analysis and previously linked to an antiviral response. This was substantiated by a transcriptomic IFN signature that we related to an increase in human endogenous retrovirus K envelope protein. Transfection of human endogenous retrovirus K envelope in a neutrophil cell line (HL-60) increases neutrophil elastase and IFN genes, whereas vinculin is increased by human endogenous retrovirus K deoxyuridine triphosphate diphosphatase that is elevated in patient plasma. Neutrophil EVs from patient plasma contain increased neutrophil elastase and human endogenous retrovirus K envelope and induce pulmonary hypertension in mice, mitigated by elafin, an elastase inhibitor. Conclusions: Elevated human endogenous retroviral elements and elastase link a neutrophil innate immune response to pulmonary arterial hypertension.

Pulmonary Vascular Research Institute GoDeep: A meta-registry merging deep phenotyping datafrom international PH reference centers

The Pulmonary Vascular Research Institute GoDeep meta-registry is a collaboration of pulmonary hypertension (PH) reference centers across the globe. Merging worldwide PH data in a central meta-registry to allow advanced analysis of the heterogeneity of PH and its groups/subgroups on a worldwide geographical, ethnical, and etiological landscape (ClinTrial. gov NCT05329714). Retrospective and prospective PH patient data (diagnosis based on catheterization; individuals with exclusion of PH are included as a comparator group) are mapped to a common clinical parameter set of more than 350 items, anonymized and electronically exported to a central server. Use and access is decided by the GoDeep steering board, where each center has one vote. As of April 2022, GoDeep comprised 15,742 individuals with 1.9 million data points from eight PH centers. Geographic distribution comprises 3990 enrollees (25%) from America and 11,752 (75%) from Europe. Eighty-nine perecent were diagnosed with PH and 11% were classified as not PH and provided a comparator group. The retrospective observation period is an average of 3.5 years (standard error of the mean 0.04), with 1159 PH patients followed for over 10 years. Pulmonary arterial hypertension represents the largest PH group (42.6%), followed by Group 2 (21.7%), Group 3 (17.3%), Group 4 (15.2%), and Group 5 (3.3%). The age distribution spans several decades, with patients 60 years or older comprising 60%. The majority of patients met an intermediate risk profile upon diagnosis. Data entry from a further six centers is ongoing, and negotiations with >10 centers worldwide have commenced. Using electronic interface-based automated retrospective and prospective data transfer, GoDeep aims to provide in-depth epidemiological and etiological understanding of PH and its various groups/subgroups on a global scale, offering insights for improved management.

The Right Heart Network and Risk Stratification in Pulmonary Arterial Hypertension

BACKGROUND

Prognosis in pulmonary arterial hypertension (PAH) is closely related to indexes of right ventricular function. A better understanding of their relationship may provide important implications for risk stratification in PAH.

RESEARCH QUESTION

Can clinical network graphs inform risk stratification in PAH?

STUDY DESIGN AND METHODS

The study cohort consisted of 231 patients with PAH followed up for a median of 7.1 years. An undirected, correlation network was used to visualize the relationship between clinical features in PAH. This network was enriched for right heart parameters and included N-terminal pro-hormone B-type natriuretic peptide (NT-proBNP), comprehensive echocardiographic parameters, and hemodynamics, as well as 6-min walk distance (6MWD), vital signs, laboratory data, and diffusing capacity for carbon monoxide (Dlco). Connectivity was assessed by using eigenvector and betweenness centrality to reflect global and regional connectivity, respectively. Cox proportional hazards regression was used to model event-free survival for the combined end point of death or lung transplantation.

RESULTS

A network of closely intertwined features centered around NT-proBNP with 6MWD emerging as a secondary hub were identified. Less connected nodes included Dlco, systolic BP, albumin, and sodium. Over the follow-up period, death or transplantation occurred in 92 patients (39.8%). A strong prognostic model was achieved with a Harrell's C-index of 0.81 (0.77-0.85) when combining central right heart features (NT-proBNP and right ventricular end-systolic remodeling index) with 6MWD and less connected nodes (Dlco, systolic BP, albumin, sodium, sex, connective tissue disease etiology, and prostanoid therapy). When added to the baseline risk model, serial change in NT-proBNP significantly improved outcome prediction at 5 years (increase in C-statistic of 0.071 ± 0.024; P = .003).

INTERPRETATION

NT-proBNP emerged as a central hub in the intertwined PAH network. Connectivity analysis provides explainability for feature selection and combination in outcome models.

Insulin Growth Factor Phenotypes in Heart Failure with Preserved Ejection Fraction, an INSPIRE Registry and CATHGEN Study: IGF axis in HFpEF

BACKGROUND

The insulin like growth factor (IGF) axis emerged as an important pathway in heart failure with preserved ejection (HFpEF). We aimed to identify IGF phenotypes associated with HFpEF in the context high-dimensional proteomic profiling.

METHODS

From the Intermountain INSPIRE Registry, we identified 96 patients with HFpEF and matched controls. We performed targeted proteomics including IGF-1,2, IGF binding proteins (IGFBP) 1-7 and 111 other proteins (EMD Millipore and ELISA). We used partial least square discriminant analysis (PLS-DA) to identify a set of proteins associated with prevalent HFpEF, pulmonary hypertension (PH) and 5-year-all-cause mortality. K-mean clustering was used to identify IGF phenotypes.

RESULTS

Patients with HFpEF had a high prevalence of systemic hypertension (95%) and coronary artery disease (74%). Using PLS-DA, we identified a set of biomarkers including IGF1,2 and IGFBP-1,2,7 that provided a strong discrimination of HFPEF, PH and mortality with an AUC of 0.91, 0.77 and 0.83, respectively. Using K mean clustering, we identified three IGF phenotypes that were independently associated with all-cause 5-year mortality after adjustment for age, NT-proBNP and kidney disease (p=0.004). Multivariable analysis validated the prognostic value of IGFBP-1 and 2 in the CATHGEN biorepository.

CONCLUSION

IGF phenotypes were associated with PH and mortality in HFpEF.

TORREY, a Phase 2 study to evaluate the efficacy and safety of inhaled seralutinib for the treatment of pulmonary arterial hypertension

Aberrant kinase signaling that involves platelet-derived growth factor receptor (PDGFR) α/β, colony stimulating factor 1 receptor (CSF1R), and stem cell factor receptor (c-KIT) pathways may be responsible for vascular remodeling in pulmonary arterial hypertension. Targeting these specific pathways may potentially reverse the pathological inflammation, cellular proliferation, and fibrosis associated with pulmonary arterial hypertension progression. Seralutinib (formerly known as GB002) is a novel, potent, clinical stage inhibitor of PDGFRα/β, CSF1R, and c-KIT delivered via inhalation that is being developed for patients with pulmonary arterial hypertension. Here, we report on an ongoing Phase 2 randomized, double-blind, placebo-controlled trial (NCT04456998) evaluating the efficacy and safety of seralutinib in subjects with World Health Organization Group 1 Pulmonary Hypertension who are classified as Functional Class II or III. A total of 80 subjects will be enrolled and randomized to receive either study drug or placebo for 24 weeks followed by an optional 72-week open-label extension study. The primary endpoint is the change from baseline to Week 24 in pulmonary vascular resistance by right heart catheterization. The secondary endpoint is the change in distance from baseline to Week 24 achieved in the 6-min walk test. A computerized tomography sub-study will examine the effect of seralutinib on pulmonary vascular remodelling. A separate heart rate monitoring sub-study will examine the effect of seralutinib on cardiac effort during the 6-min walk test.

"NOVEL MECHANISMS TARGETED BY DRUG TRIALS IN PULMONARY ARTERIAL HYPERTENSION"

Pulmonary arterial hypertension (PAH) is a rare disease associated with abnormally elevated pulmonary pressures and right heart failure resulting in high morbidity and mortality. While PAH prognosis has improved with the introduction of pulmonary vasodilators, disease progression remains a major problem. Given that available therapies are inadequate for preventing small vessel loss and obstruction, there is an active interest in identifying drugs capable of targeting angiogenesis and mechanisms involved in regulation of cell growth and fibrosis. Among the mechanisms linked to PAH pathogenesis, recent preclinical studies have identified promising compounds that are currently being tested in clinical trials. These drugs target seven of the major mechanisms associated with PAH pathogenesis: BMP signaling, tyrosine kinase receptors, estrogen metabolism, extracellular matrix, angiogenesis, epigenetics, and serotonin metabolism. In this review, we will discuss the preclinical studies that led to prioritization of these mechanisms and will discuss recently completed and ongoing phase 2/3 trials using novel interventions such as sotatercept, anastrozole, rodatristat ethyl, tyrosine kinase inhibitors, and endothelial progenitor cells among others. We anticipate that the next generation of compounds will build upon the success of the current standard of care and improve clinical outcomes and quality of life of patients afflicted with PAH.

Severe Pulmonary Arterial Hypertension Is Characterized by Increased Neutrophil Elastase and Relative Elafin Deficiency

BACKGROUND

Preclinical evidence implicates neutrophil elastase (NE) in pulmonary arterial hypertension (PAH) pathogenesis, and the NE inhibitor elafin is under early therapeutic investigation.

RESEARCH QUESTION

Are circulating NE and elafin levels abnormal in PAH and are they associated with clinical severity?

STUDY DESIGN AND METHODS

In an observational Stanford University PAH cohort (n = 249), plasma NE and elafin levels were measured in comparison with those of healthy control participants (n = 106). NE and elafin measurements were then related to PAH clinical features and relevant ancillary biomarkers. Cox regression models were fitted with cubic spline functions to associate NE and elafin levels with survival. To validate prognostic relationships, we analyzed two United Kingdom cohorts (n = 75 and n = 357). Mixed-effects models evaluated NE and elafin changes during disease progression. Finally, we studied effects of NE-elafin balance on pulmonary artery endothelial cells (PAECs) from patients with PAH.

RESULTS

Relative to control participants, patients with PAH were found to have increased NE levels (205.1 ng/mL [interquartile range (IQR), 123.6-387.3 ng/mL] vs 97.6 ng/mL [IQR, 74.4-126.6 ng/mL]; P < .0001) and decreased elafin levels (32.0 ng/mL [IQR, 15.3-59.1 ng/mL] vs 45.5 ng/mL [IQR, 28.1-92.8 ng/mL]; P < .0001) independent of PAH subtype, illness duration, and therapies. Higher NE levels were associated with worse symptom severity, shorter 6-min walk distance, higher N-terminal pro-type brain natriuretic peptide levels, greater right ventricular dysfunction, worse hemodynamics, increased circulating neutrophil levels, elevated cytokine levels, and lower blood BMPR2 expression. In Stanford patients, NE levels of > 168.5 ng/mL portended increased mortality risk after adjustment for known clinical predictors (hazard ratio [HR], 2.52; CI, 1.36-4.65, P = .003) or prognostic cytokines (HR, 2.63; CI, 1.42-4.87; P = .001), and the NE level added incremental value to established PAH risk scores. Similar prognostic thresholds were identified in validation cohorts. Longitudinal NE changes tracked with clinical trends and outcomes. PAH PAECs exhibited increased apoptosis and attenuated angiogenesis when exposed to NE at the level observed in patients' blood. Elafin rescued PAEC homeostasis, yet the required dose exceeded levels found in patients.

INTERPRETATION

Blood levels of NE are increased while elafin levels are deficient across PAH subtypes. Higher NE levels are associated with worse clinical disease severity and outcomes, and this target-specific biomarker could facilitate therapeutic development of elafin.

Pulmonary Arterial Hypertension Secondary to Drugs and Toxins

Pulmonary arterial hypertension secondary to drugs and toxins is an important subgroup of group 1 pulmonary hypertension associated with significant morbidity and mortality. Many drugs and toxins have emerged as risk factors for pulmonary arterial hypertension, which include anorexigens, illicit agents, and several US Food and Drug Administration-approved therapeutic medications. Drugs and toxins are classified as possible or definite risk factors for pulmonary arterial hypertension. This article reviews agents that have been implicated in the development of pulmonary arterial hypertension, their pathologic mechanisms, and methods to prevent the next deadly outbreak of drug- and toxin-induced pulmonary arterial hypertension.

Optimal Tricuspid Regurgitation Velocity to Screen for Pulmonary Hypertension in Tertiary Referral Centers

BACKGROUND

A mean pulmonary artery pressure >20 mmHg now defines pulmonary hypertension. We hypothesize that echocardiographic thresholds need to be adjusted.

RESEARCH QUESTION

Should TRV thresholds to screen for PH be revised given the new hemodynamic definition?

STUDY DESIGN AND METHODS

This multicenter retrospective study included 1,608 patients that underwent both echocardiography and right heart catherization within four weeks. The discovery cohort consisted of 1,081 individuals and the validation cohort included 527. Screening criteria for pulmonary hypertension were derived using receiver operating characteristic analysis and the Youden index assuming equal cost for false positive and negative classification. A lower threshold was calculated using a predefined sensitivity: 95%.

RESULTS

In the discovery cohort, echocardiographic tricuspid regurgitation velocity had a good discrimination for pulmonary hypertension, AUC 88.4 (95% CI, 85.3-91.5). A 3.4 m/s threshold provided a 78% sensitivity, 87% specificity, and 6.13 positive likelihood ratio to detect pulmonary hypertension. 2.7 m/s had a 95% sensitivity and 0.12 negative likelihood ratio to exclude pulmonary hypertension. In the validation cohort, the discovery threshold of 2.7 m/s provided a sensitivity and negative likelihood ratio of 80% and 0.34, respectively. Right cardiac size improved detection of pulmonary hypertension in the lower tricuspid regurgitation velocity groups.

INTERPRETATION

Our data support a lower tricuspid regurgitation velocity around 2.7 m/s for screening pulmonary hypertension with a high sensitivity in tertiary referral centers. Right heart chamber measurements improve the diagnostic yield of echocardiography.

Improving Right Ventricular Function by Increasing BMP Signaling with FK506

Right Ventricular (RV) function is the predominant determinant of survival in patients suffering from pulmonary arterial hypertension (PAH). In pre-clinical models, pharmacological activation of bone morphogenetic protein (BMP) signaling with FK506 (Tacrolimus) improved RV function by decreasing RV afterload. FK506 therapy further stabilized three end-stage PAH patients. Whether FK506 has direct effects on the pressure overloaded RV is yet unknown. We hypothesized that increasing cardiac BMP signaling with FK506 improves RV structure and function in a model of fixed RV afterload after pulmonary artery banding (PAB). Direct cardiac effects of FK506 on the microvasculature and RV fibrosis were studied after surgical PAB in wildtype and heterozygous Bmpr2 mutant mice. Right ventricular function and strain were assessed longitudinally via cardiac magnetic resonance (CMR) imaging during continuous FK506 infusion. Genetic lineage tracing of endothelial cells (ECs) was performed to assess the contribution of ECs to fibrosis. Molecular mechanistic studies were performed in human cardiac fibroblasts (hCFs) and endothelial cells. In mice, low BMP signaling in the RV exaggerated PAB-induced RV fibrosis. FK506 therapy restored cardiac BMP signaling, reduced RV fibrosis in a BMP-dependent manner independent from its immunosuppressive effect, preserved RV capillarization and improved RV function and strain over the time-course of disease. Endothelial mesenchymal transition was a rare event and did not significantly contribute to cardiac fibrosis after PAB. Mechanistically, FK506 required ALK1 in hCFs as BMPR2 co-receptor to reduce TGFβ1-induced proliferation and collagen production. Our study demonstrates that increasing cardiac BMP signaling with FK506 improves RV structure and function independent from its previously described beneficial effects on pulmonary vascular remodeling.

NHLBI-CMREF Workshop Report on Pulmonary Vascular Disease Classification: JACC State-of-the-Art Review

The National Heart, Lung, and Blood Institute and the Cardiovascular Medical Research and Education Fund held a workshop on the application of pulmonary vascular disease omics data to the understanding, prevention, and treatment of pulmonary vascular disease. Experts in pulmonary vascular disease, omics, and data analytics met to identify knowledge gaps and formulate ideas for future research priorities in pulmonary vascular disease in line with National Heart, Lung, and Blood Institute Strategic Vision goals. The group identified opportunities to develop analytic approaches to multiomic datasets, to identify molecular pathways in pulmonary vascular disease pathobiology, and to link novel phenotypes to meaningful clinical outcomes. The committee suggested support for interdisciplinary research teams to develop and validate analytic methods, a national effort to coordinate biosamples and data, a consortium of preclinical investigators to expedite target evaluation and drug development, longitudinal assessment of molecular biomarkers in clinical trials, and a task force to develop a master clinical trials protocol for pulmonary vascular disease.

Targeted proteomics of right heart adaptation to pulmonary arterial hypertension

No prior proteomic screening study has centred on the right ventricle (RV) in pulmonary arterial hypertension (PAH). This study investigates the circulating proteomic profile associated with right heart maladaptive phenotype (RHMP) in PAH.Plasma proteomic profiling was performed using multiplex immunoassay in 121 (discovery cohort) and 76 (validation cohort) PAH patients. The association between proteomic markers and RHMP, defined by the Mayo right heart score (combining RV strain, New York Heart Association (NYHA) class and N-terminal pro-brain natriuretic peptide (NT-proBNP)) and Stanford score (RV end-systolic remodelling index, NYHA class and NT-proBNP), was assessed by partial least squares regression. Biomarker expression was measured in RV samples from PAH patients and controls, and pulmonary artery banding (PAB) mice.High levels of hepatocyte growth factor (HGF), stem cell growth factor-β, nerve growth factor and stromal derived factor-1 were associated with worse Mayo and Stanford scores independently from pulmonary resistance or pressure in both cohorts (the validation cohort had more severe disease features: lower cardiac index and higher NT-proBNP). In both cohorts, HGF added value to the REVEAL score in the prediction of death, transplant or hospitalisation at 3 years. RV expression levels of HGF and its receptor c-Met were higher in end-stage PAH patients than controls, and in PAB mice than shams.High plasma HGF levels are associated with RHMP and predictive of 3-year clinical worsening. Both HGF and c-Met RV expression levels are increased in PAH. Assessing plasma HGF levels might identify patients at risk of heart failure who warrant closer follow-up and intensified therapy.

Safety and Efficacy of B-Cell Depletion with Rituximab for the Treatment of Systemic Sclerosis-associated Pulmonary Arterial Hypertension: A Multicenter, Double-Blind, Randomized, Placebo-controlled Trial

Rationale: Systemic sclerosis (SSc)-pulmonary arterial hypertension (PAH) is one of the most prevalent and deadly forms of PAH. B cells may contribute to SSc pathogenesis. Objectives: We investigated the safety and efficacy of B-cell depletion for SSc-PAH. Methods: In an NIH-sponsored, multicenter, double-blinded, randomized, placebo-controlled, proof-of-concept trial, 57 patients with SSc-PAH on stable-dose standard medical therapy received two infusions of 1,000 mg rituximab or placebo administered 2 weeks apart. The primary outcome measure was the change in 6-minute-walk distance (6MWD) at 24 weeks. Secondary endpoints included safety and invasive hemodynamics. We applied a machine learning approach to predict drug responsiveness. Measurements and Main Results: We randomized 57 subjects from 2010 to 2018. In the primary analysis, using data through Week 24, the adjusted mean change in 6MWD at 24 weeks favored the treatment arm but did not reach statistical significance (23.6 ± 11.1 m vs. 0.5 ± 9.7 m; P = 0.12). Although a negative study, when data through Week 48 were also considered, the estimated change in 6MWD at Week 24 was 25.5 ± 8.8 m for rituximab and 0.4 ± 7.4 m for placebo (P = 0.03). Rituximab treatment appeared to be safe and well tolerated. Low levels of RF (rheumatoid factor), IL-12, and IL-17 were sensitive and specific as favorable predictors of a rituximab response as measured by an improved 6MWD (receiver operating characteristic area under the curve, 0.88-0.95). Conclusions: B-cell depletion therapy is a potentially effective and safe adjuvant treatment for SSc-PAH. Future studies in these patients can confirm whether the identified biomarkers predict rituximab responsiveness. Clinical trial registered with www.clinicaltrails.gov (NCT01086540).

EmPHasis-10 as a measure of health-related quality of life in pulmonary arterial hypertension: data from PHAR

INTRODUCTION

While the performance of the emPHasis-10 (e10) score has been evaluated against limited patient characteristics within the United Kingdom, there is an unmet need for exploring the performance of the e10 score among pulmonary arterial hypertension (PAH) patients in the United States.

METHODS

Using the Pulmonary Hypertension Association Registry, we evaluated relationships between the e10 score and demographic, functional, haemodynamic and additional clinical characteristics at baseline and over time. Furthermore, we derived a minimally important difference (MID) estimate for the e10 score.

RESULTS

We analysed data from 565 PAH (75% female) adults aged mean±sd 55.6±16.0 years. At baseline, the e10 score had notable correlation with factors expected to impact quality of life in the general population, including age, education level, income, smoking status and body mass index. Clinically important parameters including 6-min walk distance and B-type natriuretic peptide (BNP)/N-terminal proBNP were also significantly associated with e10 score at baseline and over time. We generated a MID estimate for the e10 score of -6.0 points (range -5.0--7.6 points).

CONCLUSIONS

The e10 score was associated with demographic and clinical patient characteristics, suggesting that health-related quality of life in PAH is influenced by both social factors and indicators of disease severity. Future studies are needed to demonstrate the impact of the e10 score on clinical decision-making and its potential utility for assessing clinically important interventions.

Prescription Patterns for Pulmonary Vasodilators in the Treatment of Pulmonary Hypertension Associated With Chronic Lung Diseases: Insights From a Clinician Survey

Background: Pulmonary hypertension is a complication of chronic lung diseases (PH-CLD) associated with significant morbidity and mortality. Management guidelines for PH-CLD emphasize the treatment of the underlying lung disease, but the role of PH-targeted therapy remains controversial. We hypothesized that treatment approaches for PH-CLD would be variable across physicians depending on the type of CLD and the severity of PH. Methods and Results: Between May and July 2020, we conducted an online survey of PH experts asking for their preferred treatment approach in seven hypothetical cases of PH-CLD of varying severity. We assessed agreement amongst clinicians for initial therapy choice using Fleiss' kappa calculations. Over 90% of respondents agreed that they would treat cases of severe PH in the context of mild lung disease with some form of PH-targeted therapy. For cases of severe PH in the context of severe lung disease, over 70% of respondents agreed to use PH-targeted therapy. For mild PH and mild lung disease cases, <50% of respondents chose to start PH-specific therapy. There was overall poor agreement between respondents in the choice to use mono-, double or triple combination therapy with PH-specific agents in all cases. Conclusion: Although management guidelines discourage the routine use of PH-targeted therapies to treat PH-CLD patients, most physicians choose to treat patients with some form of PH-targeted therapy. The choice of therapy and treatment approach are variable and appear to be influenced by the severity of the PH and the underlying lung disease.

A Survey-based Estimate of COVID-19 Incidence and Outcomes among Patients with Pulmonary Arterial Hypertension or Chronic Thromboembolic Pulmonary Hypertension and Impact on the Process of Care

Rationale: Patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) typically undergo frequent clinical evaluation. The incidence and outcomes of coronavirus disease (COVID-19) and its impact on routine management for patients with pulmonary vascular disease is currently unknown.Objectives: To assess the cumulative incidence and outcomes of recognized COVID-19 for patients with PAH/CTEPH followed at accredited pulmonary hypertension centers, and to evaluate the pandemic's impact on clinic operations at these centers.Methods: A survey was e-mailed to program directors of centers accredited by the Pulmonary Hypertension Association. Descriptive analyses and linear regression were used to analyze results.Results: Seventy-seven center directors were successfully e-mailed a survey, and 58 responded (75%). The cumulative incidence of COVID-19 recognized in individuals with PAH/CTEPH was 2.9 cases per 1,000 patients, similar to the general U.S. population. In patients with PAH/CTEPH for whom COVID-19 was recognized, 30% were hospitalized and 12% died. These outcomes appear worse than the general population. A large impact on clinic operations was observed including fewer clinic visits and substantially increased use of telehealth. A majority of centers curtailed diagnostic testing and a minority limited new starts of medical therapy. Most centers did not use experimental therapies in patients with PAH/CTEPH diagnosed with COVID-19.Conclusions: The cumulative incidence of COVID-19 recognized in patients with PAH/CTEPH appears similar to the broader population, although outcomes may be worse. Although the total number of patients with PAH/CTEPH recognized to have COVID-19 was small, the impact of COVID-19 on broader clinic operations, testing, and treatment was substantial.

Mural Cell SDF1 Signaling Is Associated with the Pathogenesis of Pulmonary Arterial Hypertension

Pulmonary artery smooth muscle cells (PASMCs) and pericytes are NG2⁺ mural cells that provide structural support to pulmonary arteries and capillaries. In pulmonary arterial hypertension (PAH), both mural cell types contribute to PA muscularization, but whether similar mechanisms are responsible for their behavior is unknown. RNA-seq was used to compare the gene profile of pericytes and PASMCs from PAH and healthy lungs. NG2-Cre-ER mice were used to generate NG2-selective reporter mice (NG2tdT) for cell lineage identification and tamoxifen-inducible mice for NG2-selective SDF1 knockout (SDF1^NG2-KO). Hierarchical clustering of RNA-seq data demonstrated that the genetic profile of PAH pericytes and PASMCs is highly similar. Cellular lineage staining studies on NG2tdT mice in chronic hypoxia showed that, similar to PAH, tdT⁺ cells accumulate in muscularized microvessels and demonstrate significant upregulation of SDF1, a chemokine involved in chemotaxis and angiogenesis. Compared with control mice, SDF1^NG2-KO mice in chronic hypoxia had reduced muscularization and lower abundance of NG2⁺ cells around microvessels. SDF1 stimulation in healthy pericytes induced greater contractility and impaired their capacity to establish endothelial-pericyte communications. In contrast, SDF1 knockdown reduced PAH pericyte contractility and improved their capacity to associate with vascular tubes in coculture. SDF1 is upregulated in NG2⁺ mural cells and is associated with PA muscularization. Targeting SDF1 could help prevent and/or reverse muscularization in PAH.

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

BACKGROUND

The renin-angiotensin-aldosterone system (RAAS) contributes to pulmonary hypertension (PH) pathogenesis. Although animal data suggest that RAAS inhibition attenuates PH, it is unknown if RAAS inhibition is beneficial in PH patients.

RESEARCH QUESTION

Is RAAS inhibitor use associated with lower mortality in a large cohort of patients with hemodynamically confirmed PH?

STUDY DESIGN AND METHODS

We used the Department of Veterans Affairs Clinical Assessment Reporting and Tracking Database to study retrospectively relationships between RAAS inhibitors (angiotensin converting enzyme inhibitors [ACEIs], angiotensin receptor blockers [ARBs], and aldosterone antagonists [AAs]) and mortality in 24,221 patients with hemodynamically confirmed PH. We evaluated relationships in the full and in propensity-matched cohorts. Analyses were adjusted for demographics, socioeconomic status, comorbidities, disease severity, and comedication use in staged models.

RESULTS

ACEI and ARB use was associated with improved survival in unadjusted Kaplan-Meier survival analyses in the full cohort and the propensity-matched cohort. This relationship was insensitive to adjustment, independent of pulmonary artery wedge pressure, and also was observed in a cohort restricted to individuals with precapillary PH. AA use was associated with worse survival in unadjusted Kaplan-Meier survival analyses in the full cohort; however, AA use was associated less robustly with mortality in the propensity-matched cohort and was not associated with worse survival after adjustment for disease severity, indicating that AAs in real-world practice are used preferentially in sicker patients and that the unadjusted association with increased mortality may be an artifice of confounding by indication of severity.

INTERPRETATION

ACEI and ARB use is associated with lower mortality in veterans with PH. AA use is a marker of disease severity in PH. ACEIs and ARBs may represent a novel treatment strategy for diverse PH phenotypes.

Genetic Admixture and Survival in Diverse Populations with Pulmonary Arterial Hypertension

Rationale: Limited information is available on racial/ethnic differences in pulmonary arterial hypertension (PAH).Objectives: Determine effects of race/ethnicity and ancestry on mortality and disease outcomes in diverse patients with PAH.Methods: Patients with Group 1 PAH were included from two national registries with genome-wide data and two local cohorts, and further incorporated in a global meta-analysis. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for transplant-free, all-cause mortality in Hispanic patients with non-Hispanic white (NHW) patients as the reference group. Odds ratios (ORs) for inpatient-specific mortality in patients with PAH were also calculated for race/ethnic groups from an additional National Inpatient Sample dataset not included in the meta-analysis.Measurements and Main Results: After covariate adjustment, self-reported Hispanic patients (n = 290) exhibited significantly reduced mortality versus NHW patients (n = 1,970) after global meta-analysis (HR, 0.60 [95% CI, 0.41-0.87]; P = 0.008). Although not significant, increasing Native American genetic ancestry appeared to account for part of the observed mortality benefit (HR, 0.48 [95% CI, 0.23-1.01]; P = 0.053) in the two national registries. Finally, in the National Inpatient Sample, an inpatient mortality benefit was also observed for Hispanic patients (n = 1,524) versus NHW patients (n = 8,829; OR, 0.65 [95% CI, 0.50-0.84]; P = 0.001). An inpatient mortality benefit was observed for Native American patients (n = 185; OR, 0.38 [95% CI, 0.15-0.93]; P = 0.034).Conclusions: This study demonstrates a reproducible survival benefit for Hispanic patients with Group 1 PAH in multiple clinical settings. Our results implicate contributions of genetic ancestry to differential survival in PAH.

Beyond the Lungs: Systemic Manifestations of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a disease characterized by progressive loss and remodeling of the pulmonary arteries, resulting in right heart failure and death. Until recently, PAH was seen as a disease restricted to the pulmonary circulation. However, there is growing evidence that patients with PAH also exhibit systemic vascular dysfunction, as evidenced by impaired brachial artery flow-mediated dilation, abnormal cerebral blood flow, skeletal myopathy, and intrinsic kidney disease. Although some of these anomalies are partially due to right ventricular insufficiency, recent data support a mechanistic link to the genetic and molecular events behind PAH pathogenesis. This review serves as an introduction to the major systemic findings in PAH and the evidence that supports a common mechanistic link with PAH pathophysiology. In addition, it discusses recent studies describing morphological changes in systemic vessels and the possible role of bronchopulmonary anastomoses in the development of plexogenic arteriopathy. On the basis of available evidence, we propose a paradigm in which metabolic abnormalities, genetic injury, and systemic vascular dysfunction contribute to systemic manifestations in PAH. This concept not only opens exciting research possibilities but also encourages clinicians to consider extrapulmonary manifestations in their management of patients with PAH.

Care of patients with pulmonary arterial hypertension during the coronavirus (COVID-19) pandemic

The COVID-19 pandemic presents many unique challenges when caring for patients with pulmonary hypertension. The COVID-19 pandemic has altered routine standard of care practice and the acute management particularly for those patients with pulmonary arterial hypertension, where pulmonary arterial hypertension-specific treatments are used. It is important to balance the ongoing care and evaluation of pulmonary arterial hypertension patients with "exposure risk" to COVID-19 for patients coming to clinic or the hospital. If there is a morbidity and mortality benefit from starting pulmonary arterial hypertension therapies, for example in a patient with high-likelihood of pulmonary arterial hypertension, then it remains important to complete the thorough evaluation. However, the COVID-19 outbreak may also represent a unique time when pulmonary hypertension experts have to weigh the risks and benefits of the diagnostic work-up including potential exposure to COVID-19 versus initiating targeted pulmonary arterial hypertension therapy in a select high-risk, high likelihood World Symposium Pulmonary Hypertension Group 1 pulmonary arterial hypertension patients. This document will highlight some of the issues facing providers, patients, and the pulmonary arterial hypertension community in real-time as the COVID-19 pandemic is evolving and is intended to share expected common clinical scenarios and best clinical practices to help the community at-large.

Drug- and toxin-induced pulmonary arterial hypertension: Current state of the literature

Drug- and toxin-induced pulmonary arterial hypertension (PAH) is an increasingly important sub-group of group 1 pulmonary hypertension (PH). In the last 60 years, we have seen the rise and fall of numerous prescription and illicit agents that have caused severe and deadly outbreaks of PAH. Currently, drugs and toxins are classified into “possible” and “definite” risk factors for PAH. While the exact mechanisms and pathogenesis of drug- and toxin-induced PAH are currently unknown, novel clinical and basic science studies are beginning to unravel the biologic factors and genetic underpinnings responsible for disease development. The clinical management of affected patients can be challenging as it is often difficult to identify patients early and demonstrate causality between drugs and PAH. Given the recent trends in drug utilization and development, it is highly likely that we will continue to identify new agents capable of causing pulmonary vascular disease. We must keep a high index of suspicion in order to identify patients and new compounds deemed definite or likely risk factors for PAH. Practicing pharmacovigilance, raising awareness, and working in tandem with PH patient associations and drug regulatory agencies may ultimately be our most effective strategy in preventing the next deadly outbreak of drug- and toxin-induced PAH.

Discovery of Distinct Immune Phenotypes Using Machine Learning in Pulmonary Arterial Hypertension

RATIONALE

Accumulating evidence implicates inflammation in pulmonary arterial hypertension (PAH) and therapies targeting immunity are under investigation, although it remains unknown if distinct immune phenotypes exist.

OBJECTIVE

Identify PAH immune phenotypes based on unsupervised analysis of blood proteomic profiles.

METHODS AND RESULTS

In a prospective observational study of group 1 PAH patients evaluated at Stanford University (discovery cohort; n=281) and University of Sheffield (validation cohort; n=104) between 2008 and 2014, we measured a circulating proteomic panel of 48 cytokines, chemokines, and factors using multiplex immunoassay. Unsupervised machine learning (consensus clustering) was applied in both cohorts independently to classify patients into proteomic immune clusters, without guidance from clinical features. To identify central proteins in each cluster, we performed partial correlation network analysis. Clinical characteristics and outcomes were subsequently compared across clusters. Four PAH clusters with distinct proteomic immune profiles were identified in the discovery cohort. Cluster 2 (n=109) had low cytokine levels similar to controls. Other clusters had unique sets of upregulated proteins central to immune networks-cluster 1 (n=58; TRAIL [tumor necrosis factor-related apoptosis-inducing ligand], CCL5 [C-C motif chemokine ligand 5], CCL7, CCL4, MIF [macrophage migration inhibitory factor]), cluster 3 (n=77; IL [interleukin]-12, IL-17, IL-10, IL-7, VEGF [vascular endothelial growth factor]), and cluster 4 (n=37; IL-8, IL-4, PDGF-β [platelet-derived growth factor beta], IL-6, CCL11). Demographics, PAH clinical subtypes, comorbidities, and medications were similar across clusters. Noninvasive and hemodynamic surrogates of clinical risk identified cluster 1 as high-risk and cluster 3 as low-risk groups. Five-year transplant-free survival rates were unfavorable for cluster 1 (47.6%; 95% CI, 35.4%-64.1%) and favorable for cluster 3 (82.4%; 95% CI, 72.0%-94.3%; across-cluster P<0.001). Findings were replicated in the validation cohort, where machine learning classified 4 immune clusters with comparable proteomic, clinical, and prognostic features.

CONCLUSIONS

Blood cytokine profiles distinguish PAH immune phenotypes with differing clinical risk that are independent of World Health Organization group 1 subtypes. These phenotypes could inform mechanistic studies of disease pathobiology and provide a framework to examine patient responses to emerging therapies targeting immunity.

Echocardiographic evaluations of right ventriculo-arterial coupling in experimental and clinical pulmonary hypertension

BACKGROUND

Tricuspid annular systolic excursion (TAPSE) or velocities (s') and right ventricular (RV) end-systolic dimensions are predictors of outcome in patients with pulmonary hypertension (PH). We explored the value of combining peak s' and RV end-systolic area index (RVESAi) as a surrogate of RV-pulmonary artery (RV-PA) coupling in a large animal of precapillary PH as well as clinically.

METHOD

The first experimental group included four control and four piglets with thromboembolic disease. RV-PA coupling was assessed by ventricular to arterial elastance ratio (Ees/Ea) at baseline, after esmolol and dobutamine administration. Echocardiographic metrics included s', TAPSE, fractional area change (RVFAC), and RVESAi. The findings were validated in six piglets with severe PH. Clinical cohorts were stable outpatients (n = 141) and acutely decompensated pulmonary arterial hypertension (n = 48).

RESULTS

In the first experimental group, the best linear correlates of Ees/Ea were s' (R2  = .51, p < .001) and RVESAi (R2  = .50, p < .001), while RVFAC (R2  = .17, p = .01) and TAPSE showed weaker association (R2  = .21, p = .39). The ratio s'/RVESAi showed nominally but not significantly (higher) association with Ees/Ea (R2  = .58, p < .01). The association between changes in s'/RVESAi and Ees/Ea was strong (R2  = .56, p < .001). In more severe PH, Ees/Ea and changes in Ees/Ea correlated significantly with s'/RVESAi and changes in s'/RVESAi (R2  = .69; p < .001 and R2  = .64, p < .001, respectively). In the two clinical cohorts, the s'/RVESAi did not emerge as a stronger predictor of outcome than RVESAi.

CONCLUSION

RV s'/RVESAi index represents a reasonable bedside-usable surrogate of RV-PA coupling and of its acute variations in PH. Its incremental prognostic value over end-systolic dimension alone remains to be proven.

Methamphetamine use association with pulmonary diseases: a retrospective investigation of hospital discharges in California from 2005 to 2011

BACKGROUND

Methamphetamine can have acute and long-term adverse health consequences. Our objective was to determine whether methamphetamine use is associated with more hospitalisation codes for asthma exacerbation, chronic obstructive pulmonary disease (COPD) exacerbation, pneumonia and acute respiratory failure (ARF).

METHODS

The Health Care Utilization Project (HCUP) database includes retrospective inpatient discharge abstracts from 2005 through 2011 from the California state inpatient databases (SIDs). ICD-9 codes were used to identify hospitalisations for asthma exacerbation, COPD exacerbation, acute pneumonia, ARF and methamphetamine use from discharges with complete demographic data and ages 18 to 75 years. Adjusted rate ratios comparing methamphetamine users with nonusers were estimated separately for each pulmonary disease diagnosis by sex using negative binomial regression models.

RESULTS

We included 21 125 249 inpatient discharges from 2005 through 2011 in California in our analysis; 182 766 (0.87%) had methamphetamine use. The rate ratio comparing pneumonia in discharges with methamphetamine use versus those without were 1.40 (95% CI 1.18, 1.67) for women and 1.18 (95% CI 1.04, 1.35) for men; comparing ARF 1.77 (95% CI 1.59, 1.98) for women and 1.24 (95% CI 1.12, 1.37) for men; and comparing COPD exacerbation 1.40 (95% CI 1.18, 1.67) for women and 0.90 (95% CI 0.79, 1.02) for men.

CONCLUSIONS

A positive association was found when comparing inpatient hospital discharge diagnoses for methamphetamine use and those for pneumonia and ARF in both sexes. This association was not seen when comparing discharge diagnoses for methamphetamine and those for asthma exacerbation in both sexes or COPD exacerbation in men. While future investigation for is warranted, this finding may help to further characterise the pulmonary toxicity of methamphetamine.

Features and Outcomes of Methamphetamine-associated Pulmonary Arterial Hypertension

RATIONALE

Although amphetamines are recognized as "likely" agents to cause drug- and toxin-associated pulmonary arterial hypertension (PAH), (meth)amphetamine-associated PAH (Meth-APAH) has not been well described.

OBJECTIVES

To prospectively characterize the clinical presentation, histopathology, and outcomes of Meth-APAH compared with those of idiopathic PAH (iPAH).

METHODS

We performed a prospective cohort study of patients with Meth-APAH and iPAH presenting to the Stanford University Pulmonary Hypertension Program between 2003 and 2015. Clinical, pulmonary angiography, histopathology, and outcomes data were compared. We used data from the Healthcare Cost and Utilization Project to estimate the epidemiology of PAH in (meth)amphetamine users hospitalized in California.

MEASUREMENTS AND MAIN RESULTS

The study sample included 90 patients with Meth-APAH and 97 patients with iPAH. Patients with Meth-APAH were less likely to be female, but similar in age, body mass index, and 6-minute-walk distance to patients with iPAH. Patients with Meth-APAH reported more advanced heart failure symptoms, had significantly higher right atrial pressure (12.7 ± 6.8 vs. 9.8 ± 5.1 mm Hg; P = 0.001), and had lower stroke volume index (22.2 ± 7.1 vs. 25.5 ± 8.7 ml/m²; P = 0.01). Event-free survival in Meth-APAH was 64.2%, 47.2%, and 25% at 2.5, 5, and 10 years, respectively, representing more than double the risk of clinical worsening or death compared with iPAH (hazard ratio, 2.04; 95% confidence interval, 1.28-3.25; P = 0.003) independent of confounders. California data demonstrated a 2.6-fold increase in risk of PAH diagnosis in hospitalized (meth)amphetamine users.

CONCLUSIONS

Meth-APAH is a severe and progressive form of PAH with poor outcomes. Future studies should focus on mechanisms of disease and potential therapeutic considerations.

EXPRESS: Myocardial Bridge - An Unrecognized Cause of Chest Pain in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is characterized by an increased pulmonary vascular resistance resulting in progressive right ventricular hypertrophy and failure. While dyspnea on exertion is the leading symptom at diagnosis, the occurrence of chest pain, although less frequently observed, is an alarming symptom that requires immediate diagnostic work-up.

Here we report the case of a 44-year-old woman with severe end-stage group 1 PAH who had repetitive occurrences of chest pain that led to frequent emergency room visits with documented signs of myocardial ischemia on EKG and troponin leaks. A computed tomography (CT) angiogram of the coronary arteries revealed the presence of a myocardial bridge (MB). An invasive coronary angiogram confirmed a MB over the left anterior descending (LAD) artery compressing the lumen of the LAD. As the patient was deteriorating on maximal medical PAH therapy, she was listed for, and subsequently received, a bilateral lung transplantation. Recognizing that the MB would pose a significant risk for ischemia during surgery as well as continuing source for chest pain after lung transplantation, the MB was surgically “unroofed” during the transplant surgery. The patient did well after surgery and did not complain of any residual chest pain.

In conclusion, a MB compressing a segment of the coronary artery could be an under-diagnosed, but potentially not so rare cause of recurrent chest pain in PAH patients, which requires specialized diagnostic evaluation and treatment

Low-grade albuminuria in pulmonary arterial hypertension

Low-grade albuminuria, determined by the urinary albumin to creatinine ratio, has been linked to systemic vascular dysfunction and is associated with cardiovascular mortality. Pulmonary arterial hypertension is related to mutations in the bone morphogenetic protein receptor type 2, pulmonary vascular dysfunction and is increasingly recognized as a systemic disease. In a total of 283 patients (two independent cohorts) diagnosed with pulmonary arterial hypertension, 18 unaffected BMPR2 mutation carriers and 68 healthy controls, spot urinary albumin to creatinine ratio and its relationship to demographic, functional, hemodynamic and outcome data were analyzed. Pulmonary arterial hypertension patients and unaffected BMPR2 mutation carriers had significantly elevated urinary albumin to creatinine ratios compared with healthy controls ( P < 0.01; P = 0.04). In pulmonary arterial hypertension patients, the urinary albumin to creatinine ratio was associated with older age, lower six-minute walking distance, elevated levels of C-reactive protein and hemoglobin A1c, but there was no correlation between the urinary albumin to creatinine ratio and hemodynamic variables. Pulmonary arterial hypertension patients with a urinary albumin to creatinine ratio above 10 µg/mg had significantly higher rates of poor outcome ( P < 0.001). This study shows that low-grade albuminuria is prevalent in pulmonary arterial hypertension patients and is associated with poor outcome. This study shows that albuminuria in pulmonary arterial hypertension is associated with systemic inflammation and insulin resistance.

Bone Morphogenetic Protein 9 Is a Mechanistic Biomarker of Portopulmonary Hypertension

RATIONALE

BMP9 (bone morphogenetic protein 9) is a circulating endothelial quiescence factor with protective effects in pulmonary arterial hypertension (PAH). Loss-of-function mutations in BMP9, its receptors, and downstream effectors have been reported in heritable PAH.

OBJECTIVES

To determine how an acquired deficiency of BMP9 signaling might contribute to PAH.

METHODS

Plasma levels of BMP9 and antagonist soluble endoglin were measured in group 1 PAH, group 2 and 3 pulmonary hypertension (PH), and in patients with severe liver disease without PAH.

MEASUREMENTS AND MAIN RESULTS

BMP9 levels were markedly lower in portopulmonary hypertension (PoPH) versus healthy control subjects, or other etiologies of PAH or PH; distinguished PoPH from patients with liver disease without PAH; and were an independent predictor of transplant-free survival. BMP9 levels were decreased in mice with PH associated with CCl₄-induced portal hypertension and liver cirrhosis, but were normal in other rodent models of PH. Administration of ALK1-Fc, a BMP9 ligand trap consisting of the activin receptor-like kinase-1 extracellular domain, exacerbated PH and pulmonary vascular remodeling in mice treated with hypoxia versus hypoxia alone.

CONCLUSIONS

BMP9 is a sensitive and specific biomarker of PoPH, predicting transplant-free survival and the presence of PAH in liver disease. In rodent models, acquired deficiency of BMP9 signaling can predispose to or exacerbate PH, providing a possible mechanistic link between PoPH and heritable PAH. These findings describe a novel experimental model of severe PH that provides insight into the synergy between pulmonary vascular injury and diminished BMP9 signaling in the pathogenesis of PAH.