Samar Farha

Sotatercept, a first‐in‐class activin signaling inhibitor, improves pulmonary vascular hemodynamics and clinical outcomes in pulmonary arterial hypertension (PAH). However, despite reductions in mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR), cardiac output (CO) does not generally increase, and some patients experience a decline in CO, a finding of unclear clinical significance. We sought to characterize the heterogeneity of CO responses to sotatercept in PAH and to determine whether incorporating oxygen delivery (DO ₂ ) provides additional insight into the physiological significance of these changes. We retrospectively analyzed PAH patients who underwent right heart catheterization before and during sotatercept therapy (median 7.3 months, IQR 4.8, 9.3). Hemodynamic, echocardiographic, hematologic, and clinical parameters were collected, including functional class, 6‐min walk distance (6MWD) and N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP). Patients were dichotomized by CO response (decreased vs. maintained), and DO ₂ was calculated at each catheterization. A total of 56 patients were included. While most demonstrated reductions in PVR and mPAP, 63% experienced decreased CO. Improvements in 6MWD and NT‐proBNP were similar between groups, and hemoglobin increased comparably. However, among patients with decreased CO, 63% had a concomitant decline in DO ₂ accompanied by worsening 6MWD and a reduced NT‐proBNP response. In this real‐world cohort, over half of sotatercept‐treated PAH patients experienced reduced CO despite overall hemodynamic and clinical improvement. Concomitant reductions in DO ₂ identify a subgroup with worse functional outcomes. These findings suggest that DO ₂ adds additional information beyond CO alone when assessing the physiological response to sotatercept.

Background: The current classification of pulmonary hypertension (PH), based largely on expert opinion, has limitations in prognostication and guiding therapies. We hypothesize that novel PH clusters that predict survival will reveal mechanistic phenotypes associated with biomarkers of vascular health across all PH groups. Methods: We first identify novel PH clinical clusters by performing unsupervised clustering analysis on the CC‐PH (Cleveland Clinic PH) registry (N=1529). We develop classification models to predict the new PH clusters and then apply them to the multicenter PVDOMICS (Pulmonary Vascular Diseases Phenomics) cohort (N=853) for validation. We compare transplantation‐free survival across the new PH clusters. We quantify metabolites of the arginine‐nitric oxide pathway and D‐dimer levels and calculate global arginine bioavailability (arginine/[ornithine+citrulline]) to assess endothelial function and activation in the new clusters and link these biomarkers to clinical outcomes. Results: Clustering analysis identify 3 clear clusters in CC ‐ PH that are validated in PVDOMICS and outperform conventional classifications in predicting transplantation‐free survival. The phenotype associated with the worst survival is characterized by reduced lung diffusion capacity, decreased arginine bioavailability and nitrate levels, and elevated D‐dimer levels, consistent with loss of pulmonary microcirculation and endothelial dysfunction. Conclusions: We identify new informative PH phenotypes associated with mortality and defined by biomarkers of endothelial function and activation. Loss of endothelial health and pronounced pulmonary vascular rarefication contribute more substantially to mortality across the spectrum of PH than right heart function. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02980887.

Aims: Alterations of mitochondrial bioenergetics and arginine metabolism are universally present and mechanistically linked to pulmonary arterial hypertension (PAH), but there is little knowledge of arginine metabolism and mitochondrial functions across the different pulmonary hypertension (PH) groups. We hypothesize that abnormalities in mitochondrial functions are present across all PH groups and associated with clinical phenotypes. We test the hypothesis in PH patients and healthy controls from the Pulmonary Vascular Disease Phenomics Program cohort, who had comprehensive clinical phenotyping and follow-up for at least 4 years for death or transplant status. Mitochondrial transmembrane potential, superoxide production, and mass were measured by flow cytometry in fresh platelets. Metabolomics analysis was performed on plasma samples. Global arginine bioavailability was calculated as the ratio of arginine/(ornithine+citrulline). Results: Global arginine bioavailability is consistently lower than controls in all PH groups. Although the mitochondrial mass is similar across all PH groups and controls, superoxide production and transmembrane potential vary across groups. Mitochondrial superoxide is higher in group 1 PAH and lowest in group 3 compared with other groups, while transmembrane potential is lower in group 1 PAH than controls or group 3. The alterations in mitochondrial functions of group 1 PAH are associated with changes in fatty acid metabolism. Mitochondrial transmembrane potential in group 1 PAH is associated with transplant-free survival. Conclusion: While alterations in mitochondrial function are found in all PH groups, group 1 PAH has a unique mitochondrial phenotype with greater superoxide and lower transmembrane potential linked to fatty acid metabolism, and clinically to survival. Antioxid. Redox Signal. 42, 361–377.

Cone-beam computed tomography (CBCT) combined with contrast-free pulmonary angiography (CFPA) is a novel lung scanning technology capable of assessing pulmonary vascular morphology in vivo in murine models.

BACKGROUND: Systemic corticosteroids have been shown to improve outcomes in severe coronavirus disease 2019 (COVID-19) pneumonia; however, their role in post-COVID-19 persistent lung abnormalities is not well defined. Here, we describe our experience with corticosteroids in patients with persistent lung infiltrates following COVID-19 infection. RESEARCH QUESTION: What is the efficacy of systemic corticosteroids in improving lung function and radiological abnormalities in patients following COVID-19 pneumonia? STUDY DESIGN AND METHODS: This is a single-center retrospective study evaluating patients with persistent respiratory symptoms and abnormal chest computed tomography findings. Patients were divided into two groups based on treatment with corticosteroids: “steroid group” and “nonsteroid group.” Clinical data were collected from the electronic medical records. RESULTS: Between March 2020 and December 2021, 227 patients were seen in the post-COVID-19 pulmonary clinic, of which 75 were included in this study. The mean age was 56 years, 63% were female, and 75% were white. The main physiologic deficit was reduced Diffusing capacity of the Lungs for Carbon Monoxide (DLCO) at 72% (±22). On chest imaging, the most common findings were ground-glass opacities (91%) and consolidation (29%). Thirty patients received corticosteroid (steroid group) and 45 did not (nonsteroid group). Patients treated with corticosteroids had lower DLCO (DLCO [%]: steroid group 63 ± 17, nonsteroid group 78 ± 23; P = 0.005) and all had ground-glass opacities on imaging compared to 84% in the nonsteroid group (P = 0.04). At follow-up, patients in the steroid group (n = 16) had a significant improvement in spirometry and DLCO. In addition, there was a significant improvement with resolution of ground-glass opacities in both the groups (P < 0.05). CONCLUSION: The use of systemic corticosteroids in patients with persistent respiratory symptoms and radiological abnormalities post-COVID-19 was associated with significant improvement in pulmonary function testing and imaging. Prospective studies are needed to confirm whether these findings are the effect of corticosteroid therapy or disease evolution over time.

Background: The aim of this study is to present the first United Arab Emirates pulmonary hypertension registry of patients’ clinical characteristics, hemodynamic parameters and treatment outcomes. Method: This is a retrospective study describing all the adult patients who underwent a right heart catheterization for evaluation of pulmonary hypertension (PH) between January 2015 and December 2021 in a tertiary referral center in Abu Dhabi, United Arab Emirates. Results: A total of 164 consecutive patients were diagnosed with PH during the five years of the study. Eighty-three patients (50.6%) were World Symposium PH Group 1-PH; nineteen patients (11.6%) were Group 2-PH due to left heart disease; twenty-three patients (14.0%) were Group 3-PH due to chronic lung disease; thirty-four patients (20.7%) were Group 4-PH due to chronic thromboembolic lung disease, and five patients (3.0%) were Group 5-PH. Among Group 1-PH, twenty-five (30%) had idiopathic, twenty-seven (33%) had connective tissue disease, twenty-six (31%) had congenital heart disease, and five patients (6%) had porto-pulmonary hypertension. The median follow-up was 55.6 months. Most of the patients were started on dual then sequentially escalated to triple combination therapy. The 1-, 3- and 5-year cumulative probabilities of survival for Group 1-PH were 86% (95% CI, 75–92%), 69% (95% CI, 54–80%) and 69% (95% CI, 54–80%). Conclusions: This is the first registry of Group 1-PH from a single tertiary referral center in the UAE. Our cohort was younger with a higher percentage of patients with congenital heart disease compared to cohorts from Western countries but similar to registries from other Asian countries. Mortality is comparable to other major registries. Adopting the new guideline recommendations and improving the availability and adherence to medications are likely to play a significant role in improving outcomes in the future.

Alterations in metabolism and bioenergetics are hypothesized in the mechanisms leading to pulmonary vascular remodeling and heart failure in pulmonary hypertension (PH). To test this, we performed metabolomic analyses on 30 PH individuals and 12 controls. Furthermore, using 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET), we dichotomized PH patients into metabolic phenotypes of high and low right ventricle (RV) glucose uptake and followed them longitudinally. In support of metabolic alterations in PH and its progression, the high RV glucose group had higher RVSP (p < 0.001), worse RV function as measured by RV fractional area change and peak global longitudinal strain (both p < 0.05) and may be associated with poorer outcomes (33% death or transplantation in the high glucose RV uptake group compared to 7% in the low RV glucose uptake group at 5 years follow up, log-ranked p = 0.07). Pathway enrichment analysis identified key metabolic pathways including fructose catabolism, arginine-nitric oxide metabolism, tricarboxylic acid (TCA) cycle, and ketones metabolism. Integrative human protein-protein interactome network analysis of metabolomic and transcriptomic data identified key pathobiological pathways: arginine biosynthesis, TCA cycle, purine metabolism, hypoxia-inducible factor 1 and apelin signaling. These findings identify a PH metabolomic endophenotype, and for the first time link this to disease severity and outcomes.

Background: The therapeutic benefits of β-blockers are well established in left heart failure. The Pulmonary Arterial Hypertension Treatment with Carvedilol for Heart Failure [PAHTCH] study showed safety and possible benefit of carvedilol in pulmonary arterial hypertension (PAH) associated right heart failure over 6 months. This study aims at evaluating the short-term cardiovascular effects and early mechanistic biomarkers of carvedilol therapy. Methods: Thirty patients with pulmonary hypertension (PH) received low dose carvedilol (3.125 mg twice daily) for 1 week prior to randomization to placebo, low-dose, or dose-escalating carvedilol therapy. Echocardiography was performed at baseline and 1 week. Exercise capacity was assessed by 6 min walk distance (6MWD). The L-arginine/nitric oxide pathway and other biological markers of endothelial function were measured. Results: All participants tolerated 1 week of carvedilol without adverse effects. After 1 week of carvedilol, 6MWD and heart rate at peak exercise did not vary (both p > 0.1). Heart rate at rest and 1 min post walk dropped significantly (both p < 0.05) with a trend for increase in heart rate recovery (p = 0.08). Right ventricular systolic pressure (RVSP) decreased by an average of 13 mmHg (p = 0.002). Patients who had a decrease in RVSP of more than 10 mm Hg were defined as responders (n = 17), and those with a lesser drop as non-responders (n = 13). Responders had a significant drop in pulmonary vascular resistance (PVR) after 1 week of carvedilol (p = 0.004). In addition, responders had a greater decrease in heart rate at rest and 1 min post walk compared to non-responders (both p < 0.05). Responders had higher plasma arginine and global bioavailability of arginine at baseline compared to non-responders (p = 0.03 and p = 0.05, respectively). After 1 week of carvedilol, responders had greater increase in urinary nitrate (p = 0.04). Responders treated with carvedilol had a sustained drop in RVSP and PVR after 6 months of carvedilol with no change in cardiac output. Conclusions: Low-dose carvedilol for 1 week can potentially identify a PH responder phenotype that may benefit from β-blockers that is associated with less endothelial dysfunction. Clinical Trial Registration: http://www.clinicaltrials.gov. identifier: NCT01586156.

Pulmonary arterial hypertension (PAH) is a serious and often fatal disease. It is a panvasculopathy of the pulmonary microcirculation characterized by vasoconstriction and arterial obstruction due to vascular proliferation and remodeling and ultimately right ventricular failure. Mitochondrial dysfunction is a universal finding in pulmonary vascular cells of patients with PAH, and is mechanistically linked to disease origins in animal models of pulmonary hypertension. Mitochondria have their own circular DNA (mtDNA), which can be subgrouped into polymorphic haplogroup variants, some of which have been identified as at-risk or protective from cardiovascular and/or neurodegenerative diseases. Here, we hypothesized that mitochondrial haplogroups may be associated with PAH. To test this, mitochondrial haplogroups were determined in a cohort of PAH patients and controls [N = 204 Caucasians (125 PAH and 79 controls) and N = 46 African Americans (13 PAH and 33 controls)]. Haplogroup L was associated with a lower rate of PAH as compared to macrohaplogroups N and M. When haplogroups were nested based on ancestral inheritance and controlled for age, gender and race, haplogroups M and HV, JT and UK of the N macro-haplogroup had significantly higher rates of PAH compared to the ancestral L (L0/1/2 and L3) (all p ≤ 0.05). Overall, the findings suggest that mitochondrial haplogroups influence risk of PAH and that a vulnerability to PAH may have emerged under the selective enrichment of specific haplogroups that occurred with the migration of populations out of Africa.