"Dissecting the Lung Transcriptome of Pulmonary Fibrosis-associated Pulmonary Hypertension".

Integrative multiomics can help elucidate the pathophysiology of pulmonary fibrosis (PF) associated pulmonary hypertension (PH) (PF-PH). Weighted gene co-expression network analysis (WGCNA) was performed on a transcriptomic dataset of explanted lung tissue from 116 patients with PF. Patients were stratified by pulmonary vascular resistance (PVR) and differential gene expression analysis was conducted. Gene modules were correlated with hemodynamics at the time of transplantation and tested for enrichment in the lung transcriptomics signature of an independent pulmonary arterial hypertension (PAH) cohort. We found 1,250 differentially expressed genes between high and low PVR groups. WGCNA identified that black and yellowgreen modules negatively correlated with PVR, while the tan and darkgrey modules positively correlated with PVR. Additionally, the tan module showed the strongest enrichment for an independent PAH gene signature, suggesting shared gene expression patterns between PAH and PF-PH. Pharmacotranscriptomic analysis using the Connectivity Map implicated the tan and darkgrey modules as potentially pathogenic in PF-PH, given their combined module signature demonstrated a high negative connectivity score for Treprostinil, a medication used in the treatment of PF-PH, and a high positive connectivity score for Bone morphogenetic protein loss of function. Pathway enrichment analysis revealed that inflammatory pathways and oxidative phosphorylation were downregulated, whereas epithelial mesenchymal transition was upregulated in modules associated with increased PVR. Our integrative systems biology approach to the lung transcriptome of PF with and without PH identified several PH-associated co-expression modules and gene targets with shared molecular features with PAH warranting further investigation to uncover potential new therapies for PF-PH.

Pregnancy and Pulmonary Hypertension: From Preconception and Risk Stratification Through Pregnancy and Postpartum.

Pulmonary hypertension is one of the highest risk medical conditions in pregnancy and carries significant maternal morbidity and mortality as well as neonatal morbidity. Diagnosis is commonly delayed due to the nonspecific nature of early symptoms. Disease progression can lead to right ventricular failure, which carries mortality rates as high as 25% to 56%. Pregnancy-related complications arise from cardiac inability to accommodate increased plasma volume and cardiac output, decreased systemic vascular resistance, and hypercoagulability. Patients in this high-risk cohort necessitate preconception risk stratification and multidisciplinary care throughout their pregnancy and delivery planning.

Perfusion imaging heterogeneity during NO inhalation distinguishes pulmonary arterial hypertension (PAH) from healthy subjects and has potential as an imaging biomarker.

BACKGROUND: Without aggressive treatment, pulmonary arterial hypertension (PAH) has a 5-year mortality of approximately 40%. A patient's response to vasodilators at diagnosis impacts the therapeutic options and prognosis. We hypothesized that analyzing perfusion images acquired before and during vasodilation could identify characteristic differences between PAH and control subjects. METHODS: We studied 5 controls and 4 subjects with PAH using HRCT and 13NN PET imaging of pulmonary perfusion and ventilation. The total spatial heterogeneity of perfusion (CV2Qtotal) and its components in the vertical (CV2Qvgrad) and cranio-caudal (CV2Qzgrad) directions, and the residual heterogeneity (CV2Qr), were assessed at baseline and while breathing oxygen and nitric oxide (O2 + iNO). The length scale spectrum of CV2Qr was determined from 10 to 110 mm, and the response of regional perfusion to O2 + iNO was calculated as the mean of absolute differences. Vertical gradients in perfusion (Qvgrad) were derived from perfusion images, and ventilation-perfusion distributions from images of 13NN washout kinetics. RESULTS: O2 + iNO significantly enhanced perfusion distribution differences between PAH and controls, allowing differentiation of PAH subjects from controls. During O2 + iNO, CV2Qvgrad was significantly higher in controls than in PAH (0.08 (0.055-0.10) vs. 6.7 × 10-3 (2 × 10-4-0.02), p < 0.001) with a considerable gap between groups. Qvgrad and CV2Qtotal showed smaller differences: - 7.3 vs. - 2.5, p = 0.002, and 0.12 vs. 0.06, p = 0.01. CV2Qvgrad had the largest effect size among the primary parameters during O2 + iNO. CV2Qr, and its length scale spectrum were similar in PAH and controls. Ventilation-perfusion distributions showed a trend towards a difference between PAH and controls at baseline, but it was not statistically significant. CONCLUSIONS: Perfusion imaging during O2 + iNO showed a significant difference in the heterogeneity associated with the vertical gradient in perfusion, distinguishing in this small cohort study PAH subjects from controls.

NEDD9 Is a Novel and Modifiable Mediator of Platelet-Endothelial Adhesion in the Pulmonary Circulation.

Rationale: Data on the molecular mechanisms that regulate platelet-pulmonary endothelial adhesion under conditions of hypoxia are lacking, but may have important therapeutic implications. Objectives: To identify a hypoxia-sensitive, modifiable mediator of platelet-pulmonary artery endothelial cell adhesion and thrombotic remodeling. Methods: Network medicine was used to profile protein-protein interactions in hypoxia-treated human pulmonary artery endothelial cells. Data from liquid chromatography-mass spectrometry and microscale thermophoresis informed the development of a novel antibody (Ab) to inhibit platelet-endothelial adhesion, which was tested in cells from patients with chronic thromboembolic pulmonary hypertension (CTEPH) and three animal models in vivo. Measurements and Main Results: The protein NEDD9 was identified in the hypoxia thrombosome network in silico. Compared with normoxia, hypoxia (0.2% O2) for 24 hours increased HIF-1α (hypoxia-inducible factor-1α)-dependent NEDD9 upregulation in vitro. Increased NEDD9 was localized to the plasma-membrane surface of cells from control donors and patients with CTEPH. In endarterectomy specimens, NEDD9 colocalized with the platelet surface adhesion molecule P-selectin. Our custom-made anti-NEDD9 Ab targeted the NEDD9-P-selectin interaction and inhibited the adhesion of activated platelets to pulmonary artery endothelial cells from control donors in vitro and from patients with CTEPH ex vivo. Compared with control mice, platelet-pulmonary endothelial aggregates and pulmonary hypertension induced by ADP were decreased in NEDD9-/- mice or wild-type mice treated with the anti-NEDD9 Ab, which also decreased chronic pulmonary thromboembolic remodeling in vivo. Conclusions: The NEDD9-P-selectin protein-protein interaction is a modifiable target with which to inhibit platelet-pulmonary endothelial adhesion and thromboembolic vascular remodeling, with potential therapeutic implications for patients with disorders of increased hypoxia signaling pathways, including CTEPH.

The Pulmonary Embolism Response Team: Why and How?

Treatment of patients with intermediate and high-risk pulmonary embolism (PE) is a controversial area. Many therapeutic options exist, and deciding on appropriate treatment can be difficult. In addition, multiple specialties are often involved in the care of PE patients. To better organize the response to serious PE patients, several hospitals and academic centers throughout the world have created pulmonary embolism response teams (PERTs). The goal of a PERT is to have a single multidisciplinary team of experts in thromboembolic disease, who can respond rapidly to patients with acute PE, and offer consultation and implementation of the full spectrum of therapeutic options. PERT teams were modeled after rapid response teams and are meant to generate a prompt, patient-specific plan for patients with PE without having to consult multiple individual specialists. Data are emerging demonstrating the value of PERTs in reducing hospital length of stay and, possibly, patient outcomes.

Risk stratification and medical therapy of pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) remains a severe clinical condition despite the availability over the past 15 years of multiple drugs interfering with the endothelin, nitric oxide and prostacyclin pathways. The recent progress observed in medical therapy of PAH is not, therefore, related to the discovery of new pathways, but to the development of new strategies for combination therapy and on escalation of treatments based on systematic assessment of clinical response. The current treatment strategy is based on the severity of the newly diagnosed PAH patient as assessed by a multiparametric risk stratification approach. Clinical, exercise, right ventricular function and haemodynamic parameters are combined to define a low-, intermediate- or high-risk status according to the expected 1-year mortality. The current treatment algorithm provides the most appropriate initial strategy, including monotherapy, or double or triple combination therapy. Further treatment escalation is required in case low-risk status is not achieved in planned follow-up assessments. Lung transplantation may be required in most advanced cases on maximal medical therapy.

SERAPHIN haemodynamic substudy: the effect of the dual endothelin receptor antagonist macitentan on haemodynamic parameters and NT-proBNP levels and their association with disease progression in patients with pulmonary arterial hypertension.

Aims: The effect of macitentan on haemodynamic parameters and NT-proBNP levels was evaluated in pulmonary arterial hypertension (PAH) patients in the SERAPHIN study. Association between these parameters and disease progression, assessed by the primary endpoint (time to first morbidity/mortality event), was explored. Methods and results: Of the 742 randomized patients, 187 with right heart catheterization at baseline and month 6 participated in a haemodynamic sub-study. Prespecified endpoints included change from baseline to month 6 in cardiac index (CI), right atrial pressure (RAP), mean pulmonary arterial pressure (mPAP), pulmonary vascular resistance (PVR), mixed-venous oxygen saturation, and NT-proBNP. Exploratory analyses examined associations between CI, RAP, and NT-proBNP and disease progression using the Kaplan-Meier method and Cox regression models. Macitentan improved CI, RAP, mPAP, PVR and NT-proBNP vs. placebo at month 6. Absolute levels of CI, RAP and NT-proBNP at baseline and month 6, but not their changes, were associated with morbidity/mortality events. Patients with CI > 2.5 L/min/m2, RAP < 8 mmHg, or NT-proBNP < 750 fmol/ml at month 6 had a lower risk of morbidity/mortality than those not meeting these thresholds (HR 0.49, 95% CL 0.28-0.86; HR 0.72, 95% CL 0.42-1.22; and HR 0.22, 95% CL 0.15-0.33, respectively). Conclusions: For all treatment groups, baseline and month 6 values of CI, RAP, and NT-proBNP, but not their changes, were associated with morbidity/mortality events, confirming their relevance in predicting disease progression in patients with PAH. By improving those parameters, macitentan increased the likelihood of reaching threshold values associated with lower risk of morbidity/mortality.

Macitentan and morbidity and mortality in pulmonary arterial hypertension.

BACKGROUND: Current therapies for pulmonary arterial hypertension have been adopted on the basis of short-term trials with exercise capacity as the primary end point. We assessed the efficacy of macitentan, a new dual endothelin-receptor antagonist, using a primary end point of morbidity and mortality in a long-term trial. METHODS: We randomly assigned patients with symptomatic pulmonary arterial hypertension to receive placebo once daily, macitentan at a once-daily dose of 3 mg, or macitentan at a once-daily dose of 10 mg. Stable use of oral or inhaled therapy for pulmonary arterial hypertension, other than endothelin-receptor antagonists, was allowed at study entry. The primary end point was the time from the initiation of treatment to the first occurrence of a composite end point of death, atrial septostomy, lung transplantation, initiation of treatment with intravenous or subcutaneous prostanoids, or worsening of pulmonary arterial hypertension. RESULTS: A total of 250 patients were randomly assigned to placebo, 250 to the 3-mg macitentan dose, and 242 to the 10-mg macitentan dose. The primary end point occurred in 46.4%, 38.0%, and 31.4% of the patients in these groups, respectively. The hazard ratio for the 3-mg macitentan dose as compared with placebo was 0.70 (97.5% confidence interval [CI], 0.52 to 0.96; P=0.01), and the hazard ratio for the 10-mg macitentan dose as compared with placebo was 0.55 (97.5% CI, 0.39 to 0.76; P<0.001). Worsening of pulmonary arterial hypertension was the most frequent primary end-point event. The effect of macitentan on this end point was observed regardless of whether the patient was receiving therapy for pulmonary arterial hypertension at baseline. Adverse events more frequently associated with macitentan than with placebo were headache, nasopharyngitis, and anemia. CONCLUSIONS: Macitentan significantly reduced morbidity and mortality among patients with pulmonary arterial hypertension in this event-driven study. (Funded by Actelion Pharmaceuticals; SERAPHIN ClinicalTrials.gov number, NCT00660179.).

New paradigm for pulmonary arterial hypertension treatment.

PURPOSE OF REVIEW: Pulmonary arterial hypertension (PAH) was previously considered a uniformly fatal disease, with patients succumbing to right heart failure and death at an average of 3 years after diagnosis. The past 20 years, however, have seen the development of numerous targeted therapies that have changed the natural history of PAH. As more pharmacologic agents have been approved and utilized, further advances in the design of and endpoints for clinical trials. This study will review some of these notable developments. RECENT FINDINGS: The successful design and completion of long-term, event-driven trials is exemplified in three recent studies: SERAPHIN, GRIPHON, and AMBITION. SERAPHIN and GRIPHON evaluated the newer agents, macitentan, an endothelin receptor antagonist, and selexipag, a prostacyclin receptor agonist, respectively. Both trials were large-scale studies that, in addition to showing marked effect on the primary endpoint of morbidity/mortality, clearly demonstrated that assessment of long-term effects of PAH therapies is feasible for new compounds. The AMBITION study evaluated a treatment strategy, namely up-front combination therapy with tadalafil and ambrisentan compared with monotherapy and showed the combination approach to be superior at decreasing the likelihood of clinical failure. SUMMARY: The evolution of clinical trials in PAH has direct implications for care of these patients. The short and long-term benefits of combination regimens suggest that the multidrug approach to PAH should, in fact, be standard of care for this disease.

Incident and prevalent cohorts with pulmonary arterial hypertension: insight from SERAPHIN.

In SERAPHIN, a long-term, randomised, controlled trial (NCT00660179) in pulmonary arterial hypertension (PAH), macitentan significantly reduced the risk of morbidity/mortality and PAH-related death/hospitalisation. We evaluated disease progression and the effect of macitentan in treatment-naïve incident and prevalent cohorts.Patients allocated to placebo, or macitentan 3 mg or 10 mg were classified by time from diagnosis to enrolment as incident (≤6 months; n=110) or prevalent (>6 months; n=157). The risk of morbidity/mortality and PAH-related death/hospitalisation was determined using Cox regression.The risk of morbidity/mortality (Kaplan-Meier estimates at month 12: 54.4% versus 26.7%; p=0.006) and PAH-related death/hospitalisation (Kaplan-Meier estimates at month 12: 47.3% versus 19.9%; p=0.006) were significantly higher for incident versus prevalent patients receiving placebo, respectively. There was no significant difference in the risk of all-cause death between incident and prevalent cohorts (p=0.587). Macitentan 10 mg significantly reduced the risk of morbidity/mortality and PAH-related death/hospitalisation versus placebo in incident and prevalent cohorts.Incident patients had a higher risk for PAH progression compared with prevalent patients but not a higher risk of death. Macitentan delayed disease progression in both incident and prevalent PAH patients.

Bosentan added to sildenafil therapy in patients with pulmonary arterial hypertension.

The safety and efficacy of adding bosentan to sildenafil in pulmonary arterial hypertension (PAH) patients was investigated.In this prospective, double-blind, event-driven trial, symptomatic PAH patients receiving stable sildenafil (≥20 mg three times daily) for ≥3 months were randomised (1:1) to placebo or bosentan (125 mg twice daily). The composite primary end-point was the time to the first morbidity/mortality event, defined as all-cause death, hospitalisation for PAH worsening or intravenous prostanoid initiation, atrial septostomy, lung transplant, or PAH worsening. Secondary/exploratory end-points included change in 6-min walk distance and World Health Organization functional class at 16 weeks, change in N-terminal pro-brain natriuretic peptide (NT-proBNP) over time, and all-cause death.Overall, 334 PAH patients were randomised to placebo (n=175) or bosentan (n=159). A primary end-point event occurred in 51.4% of patients randomised to placebo and 42.8% to bosentan (hazard ratio 0.83, 97.31% CI 0.58-1.19; p=0.2508). The mean between-treatment difference in 6-min walk distance at 16 weeks was +21.8 m (95% CI +5.9-37.8 m; p=0.0106). Except for NT-proBNP, no difference was observed for any other end-point. The safety profile of bosentan added to sildenafil was consistent with the known bosentan safety profile.In COMPASS-2, adding bosentan to stable sildenafil therapy was not superior to sildenafil monotherapy in delaying the time to the first morbidity/mortality event.

The changing paradigm in pulmonary hypertension trials: longer duration, new endpoints.

PURPOSE OF REVIEW: Approved therapies for pulmonary arterial hypertension (PAH) currently consist of 12 agents, the majority of which were approved following short-term randomized clinical trials using change in 6 minute walk distance (6MWD) as the primary outcome. However, there is growing concern that significant improvements in this measure do not translate into morbidity and mortality benefits. RECENT FINDINGS: As a result of data questioning the association between improvements in 6 minute walk distance and improvements in outcome, PAH clinical trial design is increasingly utilizing morbidity and mortality events as a composite primary outcome. This concept was recently illustrated in the published phase 3 trial of macitentan versus placebo, during which the clinical worsening event rate was decreased by 45%. Several additional unpublished trials have been similarly designed, all of which will require extended blinded treatment time in order to accrue sufficient event rates. The definition of morbidity events has varied across clinical studies; further standardization of this parameter is necessary. SUMMARY: Although multiple direct and surrogate outcomes have been studied in PAH clinical research, rate of clinical worsening events, using prolonged, event-driven trial design, has emerged as the new standard.

Pulmonary Hypertension and Right Ventricular Failure in Emergency Medicine.

Pulmonary hypertension is a hemodynamic condition, defined as a mean pulmonary artery pressure by right-sided heart catheterization of at least 25 mm Hg at rest. It is classified into 5 general groups based on the underlying cause, with left ventricular failure and chronic obstructive pulmonary disease being 2 of the most common causes in the United States. Although the specifics of the pathophysiology will vary with the cause, appreciating the risks of pulmonary hypertension and right ventricular failure is critical to appropriately evaluating and resuscitating pulmonary hypertension patients in the emergency department (ED). Patients may present to the ED with complaints related to pulmonary hypertension or unrelated ones, but this condition will affect all aspects of care. Exertional dyspnea is the most common symptom attributable to pulmonary hypertension, but the latter should be considered in any ED patient with unexplained dyspnea on exertion, syncope, or signs of right ventricular dysfunction. Patients with right ventricular failure are often volume overloaded, and careful volume management is imperative, especially in the setting of hypotension. Vasopressors and inotropes, rather than fluid boluses, are often required in shock to augment cardiac output and reduce the risk of exacerbating right ventricular ischemia. Intubation should be avoided if possible, although hypoxemia and hypercapnia may also worsen right-sided heart function. Emergency physicians should appreciate the role of pulmonary vasodilators in the treatment of pulmonary arterial hypertension and recognize that patients receiving these medications may rapidly develop right ventricular failure and even death without these therapies. Patients may require interventions not readily available in the ED, such as a pulmonary artery catheter, inhaled pulmonary vasodilators, and mechanical support with a right ventricular assist device or extracorporeal membrane oxygenation. Therefore, early consultation with a pulmonary hypertension specialist and transfer to a tertiary care center with invasive monitoring and mechanical support capabilities is advised.

Chronic Thromboembolic Pulmonary Hypertension: the End Result of Pulmonary Embolism.

Chronic thromboembolic pulmonary hypertension (CTEPH) occurs when a pulmonary embolism fails to undergo complete thrombolysis leading to vascular occlusion and pulmonary hypertension. Despite the fact that CTEPH is a potential consequence of pulmonary embolism, diagnosis requires a high degree of vigilance as many patients will not have a history of thromboembolic disease. The ventilation perfusion scan is used to evaluate for the possibility of CTEPH although right heart catheterization and pulmonary artery angiogram are needed to confirm the diagnosis. Pulmonary thromboendarterectomy is the first-line treatment for patients who are surgical candidates. Recently, riociguat has been approved for patients with nonsurgical disease or residual pulmonary hypertension despite surgical intervention. This review describes the pathophysiology, risk factors, diagnosis, and management of CTEPH.

Reliance on end-expiratory wedge pressure leads to misclassification of pulmonary hypertension.

Current guidelines recommend measurement of pulmonary artery wedge pressure (PAWP) at end-expiration. However, this recommendation is not universally followed and may not be physiologically appropriate. We investigated the performance of end-expiratory PAWP in the evaluation of precapillary pulmonary hypertension patients. 329 spontaneously breathing patients undergoing right heart catheterisation were retrospectively classified as having a precapillary, post-capillary or mixed phenotype based on standardised clinical criteria. Tracings were reviewed to compare end-expiratory PAWP with PAWP averaged throughout the respiratory cycle; these values were correlated with the clinical classifications. Predictors of large respirophasic variation in PAWP were determined. Elevated end-expiratory PAWP (>15 mmHg) occurred in 29% of subjects with precapillary phenotype. There were no differences in demographics or clinical history between those with elevated and normal end-expiratory PAWP. Those with elevated end-expiratory PAWP had greater right atrial pressure and respirophasic PAWP variation. Among all subjects, the magnitude of respirophasic variation in PAWP was positively correlated with body mass index and respirophasic variation in left ventricular end-diastolic pressure. A significant proportion of precapillary pulmonary hypertension patients have end-expiratory PAWP >15 mmHg. Spontaneous positive end-expiratory intrathoracic pressure may contribute; in those cases, PAWP averaged throughout respiration may be a more accurate measurement.

Chronic thromboembolic pulmonary hypertension: evolution in management.

PURPOSE OF REVIEW: Chronic thromboembolic pulmonary hypertension (CTEPH) is an important cause of pulmonary hypertension. Although surgery is potentially curative, some patients present with inoperable disease. In these patients, medical therapies for pulmonary arterial hypertension are increasingly being used. RECENT FINDINGS: The pathobiology of CTEPH development remains incompletely understood; however, evidence supports both large and small vessel disorder in patients with the disease. Surgical thromboendarterectomy is an increasingly well tolerated and often curative procedure and is the management strategy of choice for most patients. Although excellent outcomes in surgical management have been noted, the role of medical management in selected patients with inoperable or recurrent or persistent disease after surgery is increasing. A recent large, randomized controlled clinical trial of riociguat in CTEPH demonstrated improvements in exercise capacity, functional class, and hemodynamics. A safe, effective angioplasty approach to CTEPH is being pursued in addition. SUMMARY: The approach to CTEPH management in the operable patient remains surgical, without clear benefit to preoperative pulmonary arterial hypertension-specific therapy at this time. Patients with inoperable disease or pulmonary hypertension following thromboendarterectomy, however, should be considered for medical management, with riociguat currently having the strongest evidence specific to CTEPH.