Pulmonary arterial hypertension treatment: an individual participant data network meta-analysis

BACKGROUND AND AIMS

Effective therapies that target three main signalling pathways are approved to treat pulmonary arterial hypertension (PAH). However, there are few large patient-level studies that compare the effectiveness of these pathways. The aim of this analysis was to compare the effectiveness of the treatment pathways in PAH and to assess treatment heterogeneity.

METHODS

A network meta-analysis was performed using individual participant data of 6811 PAH patients from 20 Phase III randomized clinical trials of therapy for PAH that were submitted to the US Food and Drug Administration. Individual drugs were grouped by the following treatment pathways: endothelin, nitric oxide, and prostacyclin pathways.

RESULTS

The mean (±standard deviation) age of the sample was 49.2 (±15.4) years; 78.4% were female, 59.7% had idiopathic PAH, and 36.5% were on background PAH therapy. After covariate adjustment, targeting the endothelin + nitric oxide pathway {β: 43.7 m [95% confidence interval (CI): 32.9, 54.4]}, nitric oxide pathway [β: 29.4 m (95% CI: 22.6, 36.3)], endothelin pathway [β: 25.3 m (95% CI: 19.8, 30.8)], and prostacyclin pathway [oral/inhaled β: 19.1 m (95% CI: 14.2, 24.0), intravenous/subcutaneous β: 24.4 m (95% CI: 15.1, 33.7)] significantly increased 6 min walk distance at 12 or 16 weeks compared with placebo. Treatments also significantly reduced the likelihood of having clinical worsening events. There was significant heterogeneity of treatment effects by age, body mass index, hypertension, diabetes, and coronary artery disease.

CONCLUSIONS

Drugs targeting the three traditional treatment pathways significantly improve outcomes in PAH, with significant treatment heterogeneity in patients with some comorbidities. Randomized clinical trials are warranted to identify the most effective treatment strategies in a personalized approach.

Investigating the "sex paradox" in pulmonary arterial hypertension: Results from the Pulmonary Hypertension Association Registry (PHAR)

BACKGROUND

Female sex is a significant risk factor for pulmonary arterial hypertension (PAH), yet males with PAH have worse survival - a phenomenon referred to as the "sex paradox" in PAH.

METHODS

All adult PAH patients in the Pulmonary Hypertension Association Registry (PHAR) with congruent sex and gender were included. Baseline differences in demographics, hemodynamics, functional parameters, and quality of life were assessed by sex. Kaplan-Meier survival analysis was used to evaluate survival by sex. Mediation analysis was conducted with Cox proportional hazards regression by comparing the unadjusted hazard ratios for sex before and after adjustment for covariates. The plausibility of collider-stratification bias was assessed by modeling how large an unmeasured factor would have to be to generate the observed sex-based mortality differences. Subgroup analysis was performed on idiopathic and incident patients.

RESULTS

Among the 1,891 patients included, 75% were female. Compared to men, women had less favorable hemodynamics, lower 6-minute walk distance, more PAH therapies, and worse functional class; however, sex-based differences were less pronounced when accounting for body surface area or expected variability by gender. On multivariate analysis, women had a 48% lower risk of death compared to men (Hazard Ratio 0.52, 95% Confidence interval 0.36 - 0.74, p < 0.001). Modeling found that under reasonable assumptions collider-stratification could account for sex-based differences in mortality.

CONCLUSIONS

In this large registry of PAH patients new to a care center, men had worse survival than women despite having more favorable baseline characteristics. Collider-stratification bias could account for the observed greater mortality among men.

Predicting Acute Brain Injury in Venoarterial Extracorporeal Membrane Oxygenation Patients with Tree-Based Machine Learning: Analysis of the Extracorporeal Life Support Organization Registry

Objective

To determine if machine learning (ML) can predict acute brain injury (ABI) and identify modifiable risk factors for ABI in venoarterial extracorporeal membrane oxygenation (VA-ECMO) patients.

Design

Retrospective cohort study of the Extracorporeal Life Support Organization (ELSO) Registry (2009-2021).

Setting

International, multicenter registry study of 676 ECMO centers.

Patients

Adults (≥18 years) supported with VA-ECMO or extracorporeal cardiopulmonary resuscitation (ECPR).

Interventions

None.

Measurements and Main Results

Our primary outcome was ABI: central nervous system (CNS) ischemia, intracranial hemorrhage (ICH), brain death, and seizures. We utilized Random Forest, CatBoost, LightGBM and XGBoost ML algorithms (10-fold leave-one-out cross-validation) to predict and identify features most important for ABI. We extracted 65 total features: demographics, pre-ECMO/on-ECMO laboratory values, and pre-ECMO/on-ECMO settings.Of 35,855 VA-ECMO (non-ECPR) patients (median age=57.8 years, 66% male), 7.7% (n=2,769) experienced ABI. In VA-ECMO (non-ECPR), the area under the receiver-operator characteristics curves (AUC-ROC) to predict ABI, CNS ischemia, and ICH was 0.67, 0.67, and 0.62, respectively. The true positive, true negative, false positive, false negative, positive, and negative predictive values were 33%, 88%, 12%, 67%, 18%, and 94%, respectively for ABI. Longer ECMO duration, higher 24h ECMO pump flow, and higher on-ECMO PaO2 were associated with ABI.Of 10,775 ECPR patients (median age=57.1 years, 68% male), 16.5% (n=1,787) experienced ABI. The AUC-ROC for ABI, CNS ischemia, and ICH was 0.72, 0.73, and 0.69, respectively. The true positive, true negative, false positive, false negative, positive, and negative predictive values were 61%, 70%, 30%, 39%, 29% and 90%, respectively, for ABI. Longer ECMO duration, younger age, and higher 24h ECMO pump flow were associated with ABI.

Conclusions

This is the largest study predicting neurological complications on sufficiently powered international ECMO cohorts. Longer ECMO duration and higher 24h pump flow were associated with ABI in both non-ECPR and ECPR VA-ECMO.

Utilizing Machine Learning to Predict Neurological Injury in Venovenous Extracorporeal Membrane Oxygenation Patients: An Extracorporeal Life Support Organization Registry Analysis

Background

Venovenous extracorporeal membrane oxygenation (VV-ECMO) is associated with acute brain injury (ABI), including central nervous system (CNS) ischemia (defined as ischemic stroke or hypoxic-ischemic brain injury) and intracranial hemorrhage (ICH). There is limited data on prediction models for ABI and neurological outcomes in VV-ECMO.

Research Question

Can machine learning (ML) accurately predict ABI and identify modifiable factors of ABI in VV-ECMO?

Study Design and Methods

We analyzed adult (≥18 years) VV-ECMO patients in the Extracorporeal Life Support Organization Registry (2009-2021) from 676 centers. ABI was defined as CNS ischemia, ICH, brain death, and seizures. Overall, 65 total variables were extracted including clinical characteristics and pre-ECMO and on-ECMO variables. Random Forest, CatBoost, LightGBM, and XGBoost ML algorithms (10-fold leave-one-out cross-validation) were used to predict ABI. Feature Importance Scores were used to pinpoint variables most important for predicting ABI.

Results

Of 37,473 VV-ECMO patients (median age=48.1 years, 63% male), 2,644 (7.1%) experienced ABI: 610 (2%) and 1,591 (4%) experienced CNS ischemia and ICH, respectively. The median ECMO duration was 10 days (interquartile range=5-20 days). The area under the receiver-operating characteristics curves to predict ABI, CNS ischemia, and ICH were 0.67, 0.63, and 0.70, respectively. The accuracy, positive predictive, and negative predictive values for ABI were 79%, 15%, and 95%, respectively. ML identified pre-ECMO cardiac arrest as the most important risk factor for ABI while ECMO duration and bridge to transplantation as an indication for ECMO were associated with lower risk of ABI.

Interpretation

This is the first study to use machine learning to predict ABI in a large cohort of VV-ECMO patients. Performance was sub-optimal due to the low reported prevalence of ABI with lack of standardization of neuromonitoring/imaging protocols and data granularity in the ELSO Registry. Standardized neurological monitoring and imaging protocols may improve machine learning performance to predict ABI.

Transcriptional profiles of pulmonary artery endothelial cells in pulmonary hypertension

Pulmonary arterial hypertension (PAH) is characterized by endothelial cell (EC) dysfunction. There are no data from living patients to inform whether differential gene expression of pulmonary artery ECs (PAECs) can discern disease subtypes, progression and pathogenesis. We aimed to further validate our previously described method to propagate ECs from right heart catheter (RHC) balloon tips and to perform additional PAEC phenotyping. We performed bulk RNA sequencing of PAECs from RHC balloons. Using unsupervised dimensionality reduction and clustering we compared transcriptional signatures from PAH to controls and other forms of pulmonary hypertension. Select PAEC samples underwent single cell and population growth characterization and anoikis quantification. Fifty-four specimens were analyzed from 49 subjects. The transcriptome appeared stable over limited passages. Six genes involved in sex steroid signaling, metabolism, and oncogenesis were significantly upregulated in PAH subjects as compared to controls. Genes regulating BMP and Wnt signaling, oxidative stress and cellular metabolism were differentially expressed in PAH subjects. Changes in gene expression tracked with clinical events in PAH subjects with serial samples over time. Functional assays demonstrated enhanced replication competency and anoikis resistance. Our findings recapitulate fundamental biological processes of PAH and provide new evidence of a cancer-like phenotype in ECs from the central vasculature of PAH patients. This "cell biopsy" method may provide insight into patient and lung EC heterogeneity to advance precision medicine approaches in PAH.

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.

Interpretable machine learning-based predictive modeling of patient outcomes following cardiac surgery

BACKGROUND

The clinical applicability of machine learning predictions of patient outcomes following cardiac surgery remains unclear. We applied machine learning to predict patient outcomes associated with high morbidity and mortality after cardiac surgery and identified the importance of variables to the derived model's performance.

METHODS

We applied machine learning to the Society of Thoracic Surgeons Adult Cardiac Surgery Database to predict postoperative hemorrhage requiring reoperation, venous thromboembolism (VTE), and stroke. We used permutation feature importance to identify variables important to model performance and a misclassification analysis to study the limitations of the model.

RESULTS

The study dataset included 662,772 subjects who underwent cardiac surgery between 2015 and 2017 and 240 variables. Hemorrhage requiring reoperation, VTE, and stroke occurred in 2.9%, 1.2%, and 2.0% of subjects, respectively. The model performed remarkably well at predicting all 3 complications (area under the receiver operating characteristic curve, 0.92-0.97). Preoperative and intraoperative variables were not important to model performance; instead, performance for the prediction of all 3 outcomes was driven primarily by several postoperative variables, including known risk factors for the complications, such as mechanical ventilation and new onset of postoperative arrhythmias. Many of the postoperative variables important to model performance also increased the risk of subject misclassification, indicating internal validity.

CONCLUSIONS

A machine learning model accurately and reliably predicts patient outcomes following cardiac surgery. Postoperative, as opposed to preoperative or intraoperative variables, are important to model performance. Interventions targeting this period, including minimizing the duration of mechanical ventilation and early treatment of new-onset postoperative arrhythmias, may help lower the risk of these complications.

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

BACKGROUND

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

METHODS

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

FINDINGS

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

INTERPRETATION

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

FUNDING

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

Novel Liver Injury Phenotypes and Outcomes in Pulmonary Arterial Hypertension

Background

Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are disorders of the pulmonary vasculature that cause right ventricular dysfunction. Systemic consequences of right ventricular dysfunction include damage to other solid organs, such as the liver. However, the profiles and consequences of hepatic injury due to PAH and CTEPH have not been well-studied.

Methods

We aimed to identify underlying patterns of liver injury in a cohort of PAH and CTEPH patients enrolled in 15 randomized clinical trials conducted between 1998 and 2012. We used unsupervised machine learning to identify liver injury clusters in 13 trials and validated the findings in two additional trials. We then determined whether these liver injury clusters were associated with clinical outcomes or treatment effect heterogeneity.

Results

Our training dataset included 4,219 patients and our validation dataset included 1,756 patients with complete liver laboratory panels (serum total bilirubin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, and albumin). Using k-means clustering paired with factor analysis, we identified four unique liver phenotypes (no liver injury, hepatocellular injury, cholestatic injury, and combined injury patterns). Patients in the cholestatic injury liver cluster had the shortest time to clinical worsening and highest chance of worsening World Health Organization functional class. Randomization to the experimental arm was associated with a transition to healthier liver clusters compared to randomization to the control arm. The cholestatic injury group experienced the greatest placebo-corrected treatment benefit in terms of six-minute walk distance.

Conclusions

Liver injury patterns were associated with adverse outcomes in patients with PAH and CTEPH. Randomization to active treatment of pulmonary hypertension in these clinical trials had beneficial effects on liver health compared to placebo. The independent role of liver disease (often subclinical) in determining outcomes warrants prospective studies of the clinical utility of liver phenotyping for PAH prognosis and contribution to clinical disease.

Pulmonary Hypertension: A Contemporary Review

Major advances in pulmonary arterial hypertension, pulmonary hypertension (PH) associated with lung disease, and chronic thromboembolic PH cast new light on the pathogenetic mechanisms, epidemiology, diagnostic approach, and therapeutic armamentarium for pulmonary vascular disease. Here, we summarize key basic, translational, and clinical PH reports, emphasizing findings that build on current state-of-the-art research. This review includes cutting-edge progress in translational pulmonary vascular biology, with a guide to the diagnosis of patients in clinical practice, incorporating recent PH definition revisions that continue emphasis on early detection of disease. PH management is reviewed including an overview of the evolving considerations for the approach to treatment of PH in patients with cardiopulmonary comorbidities, as well as a discussion of the groundbreaking sotatercept data for the treatment of pulmonary arterial hypertension.

Six-Minute walk distance predicts outcomes in liver transplant candidates

A 6-minute walk test is a simple tool for assessing submaximal exercise capacity. We sought to determine whether a 6-minute walk distance (6MWD) predicts outcomes in patients with cirrhosis. The Pulmonary Vascular Complications of Liver Disease 2 study is a multicenter, prospective cohort study that enrolled adults with portal hypertension during liver transplantation evaluation. We excluded subjects with an incident or prevalent portopulmonary hypertension. The 6-minute walk test was performed using standardized methods. Cox proportional hazards modeling and multivariable linear regression analysis were performed to determine the relationship between baseline 6MWD and outcomes. The study sample included 352 subjects. The mean 6MWD was 391±101 m. For each 50-meter decrease in 6MWD, there was a 25% increase in the risk of death (HR 1.25, 95% CI [1.11, 1.41], p < 0.001) after adjustment for age, gender, body mass index, MELD-Na, and liver transplant as a time-varying covariate. In a multistate model, each 50-meter decrease in 6MWD was associated with an increased risk of death before the liver transplant ( p < 0.001) but not after the transplant. 6MWD was similar to MELD-Na in discriminating mortality. Each 50-meter decrease in 6MWD was associated with an increase in all-cause ( p < 0.001) and transplant-free hospitalizations ( p < 0.001) in multivariable models for time-to-recurrent events. Shorter 6MWD was associated with worse Short Form-36 physical ( p < 0.001) and mental component scores ( p = 0.05). In conclusion, shorter 6MWD is associated with an increased risk of death, hospitalizations, and worse quality of life in patients evaluated for liver transplantation. The 6-minute walk distance may be a useful adjunct for risk assessment in patients undergoing liver transplant evaluation.

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.

Baseline Sex Differences in Pulmonary Arterial Hypertension Randomized Clinical Trials

Rationale: Sex-based differences in pulmonary arterial hypertension (PAH) are known, but the contribution to disease measures is understudied. Objectives: We examined whether sex was associated with baseline 6-minute-walk distance (6MWD), hemodynamics, and functional class. Methods: We conducted a secondary analysis of participant-level data from randomized clinical trials of investigational PAH therapies conducted between 1998 and 2014 and provided by the U.S. Food and Drug Administration. Outcomes were modeled as a function of an interaction between sex and age or sex and body mass index (BMI), respectively, with generalized mixed modeling. Results: We included a total of 6,633 participants from 18 randomized clinical trials. A total of 5,197 (78%) were female, with a mean age of 49.1 years and a mean BMI of 27.0 kg/m2. Among 1,436 males, the mean age was 49.7 years, and the mean BMI was 26.4 kg/m2. The most common etiology of PAH was idiopathic. Females had shorter 6MWD. For every 1 kg/m2 increase in BMI for females, 6MWD decreased 2.3 (1.6-3.0) meters (P < 0.001), whereas 6MWD did not significantly change with BMI in males (0.31 m [-0.30 to 0.92]; P = 0.32). Females had lower right atrial pressure (RAP) and mean pulmonary artery pressure, and higher cardiac index than males (all P < 0.03). Age significantly modified the sex by RAP and mean pulmonary artery pressure relationships. For every 10-year increase in age, RAP was lower in males (0.5 mm Hg [0.3-0.7]; P < 0.001), but not in females (0.13 [-0.03 to 0.28]; P = 0.10). There was a significant decrease in pulmonary vascular resistance (PVR) with increasing age regardless of sex (P < 0.001). For every 1 kg/m2 increase in BMI, there was a 3% decrease in PVR for males (P < 0.001), compared with a 2% decrease in PVR in females (P < 0.001). Conclusions: Sexual dimorphism in subjects enrolled in clinical trials extends to 6MWD and hemodynamics; these relationships are modified by age and BMI. Sex, age, and body size should be considered in the evaluation and interpretation of surrogate outcomes in PAH.

Palliative care referrals in patients with pulmonary arterial hypertension: The Pulmonary Hypertension Association Registry

BACKGROUND

Pulmonary arterial hypertension (PAH) is a life limiting disease with substantial symptom burden and healthcare utilization. Palliative care alleviates physical and emotional symptoms for patients with serious illness, and has been underutilized for these patients.

OBJECTIVE

To characterize patients with PAH referred to palliative care and identify predictors of referral.

METHODS

We conducted an observational study of adult patients enrolled in the Pulmonary Hypertension Association Registry from January 2015 through June 2021, performing descriptive statistics on patient characteristics at baseline for all patients and the subset referred to palliative care. These characteristics were modeled in a backwards elimination Cox regression with time to referral to palliative care as the primary outcome.

RESULTS

92 of 1,578 patients were referred to palliative care (5.8%); 43% were referred at their last visit prior to death. Referrals were associated with increasing age per decade (hazard ratio 1.35 [95% confidence interval 1.16-1.58]), lower body mass index (hazard ratio 0.97 [95% confidence interval 0.94-0.998]), supplemental oxygen use (hazard ratio 2.01 [95% confidence interval 1.28-3.16]), parenteral prostanoid use (hazard ratio 2.88 [95% confidence interval 1.84-4.51]), and worse quality of life, measured via lower physical (hazard ratio 0.97 [95% confidence interval 0.95-0.99]) and mental (hazard ratio 0.98 [95% confidence interval 0.96-0.995]) scores on the 12-item Short Form Health Survey.

CONCLUSION

Patients with PAH are infrequently referred to palliative care, even at centers of excellence. Referrals occur in sicker patients with lower quality of life scores, often close to the end of life.

Comparison of Retinal Imaging Techniques in Individuals with Pulmonary Artery Hypertension Using Vessel Generation Analysis

(1) Background: Retinal vascular imaging plays an essential role in diagnosing and managing chronic diseases such as diabetic retinopathy, sickle cell retinopathy, and systemic hypertension. Previously, we have shown that individuals with pulmonary arterial hypertension (PAH), a rare disorder, exhibit unique retinal vascular changes as seen using fluorescein angiography (FA) and that these changes correlate with PAH severity. This study aimed to determine if color fundus (CF) imaging could garner identical retinal information as previously seen using FA images in individuals with PAH. (2) Methods: VESGEN, computer software which provides detailed vascular patterns, was used to compare manual segmentations of FA to CF imaging in PAH subjects (n = 9) followed by deep learning (DL) processing of CF imaging to increase the speed of analysis and facilitate a noninvasive clinical translation. (3) Results: When manual segmentation of FA and CF images were compared using VESGEN analysis, both showed identical tortuosity and vessel area density measures. This remained true even when separating images based on arterial trees only. However, this was not observed with microvessels. DL segmentation when compared to manual segmentation of CF images showed similarities in vascular structure as defined by fractal dimension. Similarities were lost for tortuosity and vessel area density when comparing manual CF imaging to DL imaging. (4) Conclusions: Noninvasive imaging such as CF can be used with VESGEN to provide an accurate and safe assessment of retinal vascular changes in individuals with PAH. In addition to providing insight into possible future clinical translational use.

Commercial human pulmonary artery endothelial cells have in-vitro behavior that varies by sex

It is unknown whether biological sex influences phenotypes of commercially available human pulmonary artery endothelial cells (HPAECs). Ten lots of commercial HPAECs were used (Lonza Biologics; PromoCell). Five (50%) were confirmed to be genotypically male (SRY+) and five (50%) were confirmed to be female (SRY-). Experiments were conducted between passages five and eight. HPAEC phenotype was confirmed with a panel of cell expression markers. Standard assays for proliferation, migration and tube formation were performed in triplicate with technical replicates, under three treatment conditions (EndoGRO; Sigma-Aldrich). Apoptosis was assessed by exposing cells treated with complete media or low serum media to hypoxic (1% oxygen) or normoxic (20% oxygen) conditions. Laboratory staff was blinded. The median (range) age of male and female donors from whom the HPAECs were derived was 58 (48-60) and 56 (33-67), respectively. Our results suggest decreased proliferation in genotypically female cells compared with male cells (p = 0.09). With increasing donor age, female cells were less proliferative and male cells were more proliferative (p = 0.001). Female cells were significantly more apoptotic than male cells by condition (p = 0.001). Female cells were significantly more migratory than male cells in complete media but less migratory than male cells under vascular endothelial growth factor enriched conditions (p = 0.001). There are subtle sex-based differences in the behavior of HPAECs that depend on donor sex and, less so, age. These differences may undermine rigor and reproducibility. Future studies should define whether biological sex is an important regulator of HPAEC function in health and disease.

Deep RNA sequencing of intensive care unit patients with COVID-19

COVID-19 has impacted millions of patients across the world. Molecular testing occurring now identifies the presence of the virus at the sampling site: nasopharynx, nares, or oral cavity. RNA sequencing has the potential to establish both the presence of the virus and define the host's response in COVID-19. Single center, prospective study of patients with COVID-19 admitted to the intensive care unit where deep RNA sequencing (> 100 million reads) of peripheral blood with computational biology analysis was done. All patients had positive SARS-CoV-2 PCR. Clinical data was prospectively collected. We enrolled fifteen patients at a single hospital. Patients were critically ill with a mortality of 47% and 67% were on a ventilator. All the patients had the SARS-CoV-2 RNA identified in the blood in addition to RNA from other viruses, bacteria, and archaea. The expression of many immune modulating genes, including PD-L1 and PD-L2, were significantly different in patients who died from COVID-19. Some proteins were influenced by alternative transcription and splicing events, as seen in HLA-C, HLA-E, NRP1 and NRP2. Entropy calculated from alternative RNA splicing and transcription start/end predicted mortality in these patients. Current upper respiratory tract testing for COVID-19 only determines if the virus is present. Deep RNA sequencing with appropriate computational biology may provide important prognostic information and point to therapeutic foci to be precisely targeted in future studies.

Chitinase 3-like-1 contributes to the development of pulmonary vascular remodeling in pulmonary hypertension

Chitinase 3-like 1 (CHI3L1) is the prototypic chitinase-like protein mediating inflammation, cell proliferation, and tissue remodeling. Limited data suggests CHI3L1 is elevated in human pulmonary arterial hypertension (PAH) and is associated with disease severity. Despite its importance as a regulator of injury/repair responses, the relationship between CHI3L1 and pulmonary vascular remodeling is not well understood. We hypothesize that CHI3L1 and its signaling pathways contribute to the vascular remodeling responses that occur in pulmonary hypertension (PH). We examined the relationship of plasma CHI3L1 levels and severity of PH in patients with various forms of PH, including Group 1 PAH and Group 3 PH, and found that circulating levels of serum CHI3L1 were associated with worse hemodynamics and correlated directly with mean pulmonary artery pressure and pulmonary vascular resistance. We also used transgenic mice with constitutive knockout and inducible overexpression of CHI3L1 to examine its role in hypoxia-, monocrotaline-, and bleomycin-induced models of pulmonary vascular disease. In all 3 mouse models of pulmonary vascular disease, pulmonary hypertensive responses were mitigated in CHI3L1 null mice and accentuated in transgenic mice that overexpress CHI3L1. Finally, CHI3L1 alone was sufficient to induce pulmonary arterial smooth muscle cell proliferation, inhibit pulmonary vascular endothelial cell apoptosis, induce the loss of endothelial barrier function, and induce endothelial-to-mesenchymal transition. These findings demonstrate that CHI3L1 and its receptors play an integral role in pulmonary vascular disease pathobiology and may offer a novel target for the treatment PAH and PH associated with fibrotic lung disease.

Selective serotonin reuptake inhibitors and lung function in the multi-ethnic study of atherosclerosis lung study

OBJECTIVE

Depression in patients with Chronic Obstructive Pulmonary Disease (COPD) has been shown to be chronic and potentially increase the burden of symptoms. Selective serotonin reuptake inhibitors (SSRIs) have anti-inflammatory and serotonergic effects that may improve lung function. We hypothesized that participants taking SSRIs have better lung function than those not taking SSRIs. The dataset was the Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study. Use of SSRIs was assessed by medication inventory; spirometry was conducted following standard guidelines; dyspnea ratings were self-reported.

RESULTS

Contrary to our hypothesis, FEV1 was lower, and odds of dyspnea were higher among participants taking SSRIs as compared with those not taking an antidepressant; these differences persisted even with control for potential confounders including depressive symptoms. We found no evidence of a beneficial association between SSRI use and lung function or dyspnea in a large US-based cohort.

Group 3 Pulmonary Hypertension: From Bench to Bedside

Pulmonary hypertension (PH) because of chronic lung disease is categorized as Group 3 PH in the most recent classification system. Prevalence of these diseases is increasing over time, creating a growing need for effective therapeutic options. Recent approval of the first pulmonary arterial hypertension therapy for the treatment of Group 3 PH related to interstitial lung disease represents an encouraging advancement. This review focuses on molecular mechanisms contributing to pulmonary vasculopathy in chronic hypoxia, the pathology and epidemiology of Group 3 PH, the right ventricular dysfunction observed in this population and clinical trial data that inform the use of pulmonary vasodilators in Group 3 PH.

Retinal vessel changes in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is classically considered an isolated small vessel vasculopathy of the lungs with peripheral pulmonary vascular obliteration. Systemic manifestations of PAH are increasingly acknowledged, but data remain limited. We hypothesized that retinal vascular changes occur in PAH. PAH subjects underwent retinal fluorescein angiography (FA) and routine disease severity measures were collected from the medical record. FA studies were analyzed using VESsel GENerational Analysis (VESGEN), a noninvasive, user‐interactive computer software that assigns branching generation to large and small vessels. FAs from controls (n = 8) and PAH subjects (n = 9) were compared. The tortuosity of retinal arteries was higher in PAH subjects compared to unmatched controls (1.17, 95% confidence interval: [1.14, 1.20] in PAH vs. 1.13, 95% CI: [1.12, 1.14] in controls, p = 0.01). Venous tortuosity was higher and more variable in PAH (1.17, 95% CI: [1.14, 1.20]) compared to controls (1.13, 95% CI: [1.12, 1.15]), p = 0.02. PAH subjects without connective tissue disease had the highest degree of retinal tortuosity relative to controls (arterial, p = 0.01; venous, p = 0.03). Younger PAH subjects had greater retinal arterial tortuosity, which attenuated with age and was not observed in controls. Retinal vascular parameters correlated with some clinical measures of disease in PAH subjects. In conclusion, PAH subjects exhibit higher retinal vascular tortuosity. Retinal vascular changes may track with pulmonary vascular disease progression. Use of FA and VESGEN may facilitate early, noninvasive detection of PAH.

Targeting RUNX1 as a novel treatment modality for pulmonary arterial hypertension

AIMS

Pulmonary arterial hypertension (PAH) is a fatal disease without a cure. Previously, we found that transcription factor RUNX1-dependent haematopoietic transformation of endothelial progenitor cells may contribute to the pathogenesis of PAH. However, the therapeutic potential of RUNX1 inhibition to reverse established PAH remains unknown. In the current study, we aimed to determine whether RUNX1 inhibition was sufficient to reverse Sugen/hypoxia (SuHx)-induced pulmonary hypertension (PH) in rats. We also aimed to demonstrate possible mechanisms involved.

METHODS AND RESULTS

We administered a small molecule specific RUNX1 inhibitor Ro5-3335 before, during, and after the development of SuHx-PH in rats to investigate its therapeutic potential. We quantified lung macrophage recruitment and activation in vivo and in vitro in the presence or absence of the RUNX1 inhibitor. We generated conditional VE-cadherin-CreERT2; ZsGreen mice for labelling adult endothelium and lineage tracing in the SuHx-PH model. We also generated conditional Cdh5-CreERT2; Runx1(flox/flox) mice to delete Runx1 gene in adult endothelium and LysM-Cre; Runx1(flox/flox) mice to delete Runx1 gene in cells of myeloid lineage, and then subjected these mice to SuHx-PH induction. RUNX1 inhibition in vivo effectively prevented the development, blocked the progression, and reversed established SuHx-induced PH in rats. RUNX1 inhibition significantly dampened lung macrophage recruitment and activation. Furthermore, lineage tracing with the inducible VE-cadherin-CreERT2; ZsGreen mice demonstrated that a RUNX1-dependent endothelial to haematopoietic transformation occurred during the development of SuHx-PH. Finally, tissue-specific deletion of Runx1 gene either in adult endothelium or in cells of myeloid lineage prevented the mice from developing SuHx-PH, suggesting that RUNX1 is required for the development of PH.

CONCLUSION

By blocking RUNX1-dependent endothelial to haematopoietic transformation and pulmonary macrophage recruitment and activation, targeting RUNX1 may be as a novel treatment modality for pulmonary arterial hypertension.

Pneumonia initiates a tauopathy

Pneumonia causes short‐ and long‐term cognitive dysfunction in a high proportion of patients, although the mechanism(s) responsible for this effect are unknown. Here, we tested the hypothesis that pneumonia‐elicited cytotoxic amyloid and tau variants: (1) are present in the circulation during infection; (2) lead to impairment of long‐term potentiation; and, (3) inhibit long‐term potentiation dependent upon tau. Cytotoxic amyloid and tau species were recovered from the blood and the hippocampus following pneumonia, and they were present in the extracorporeal membrane oxygenation oxygenators of patients with pneumonia, especially in those who died. Introduction of immunopurified blood‐borne amyloid and tau into either the airways or the blood of uninfected animals acutely and chronically impaired hippocampal information processing. In contrast, the infection did not impair long‐term potentiation in tau knockout mice and the amyloid‐ and tau‐dependent disruption in hippocampal signaling was less severe in tau knockout mice. Moreover, the infection did not elicit cytotoxic amyloid and tau variants in tau knockout mice. Therefore, pneumonia initiates a tauopathy that contributes to cognitive dysfunction.

Critical Care Management of the Patient with Pulmonary Hypertension

Pulmonary hypertension patients admitted to the intensive care unit have high mortality, and right ventricular failure typically is implicated as cause of or contributor to death. Initial care of critically ill pulmonary hypertension patients includes recognition of right ventricular failure, appropriate monitoring, and identification and treatment of any inciting cause. Management centers around optimization of cardiac function, with a multipronged approach aimed at reversing the pathophysiology of right ventricular failure. For patients who remain critically ill or in shock despite medical optimization, mechanical circulatory support can be used as a bridge to recovery or lung transplantation.

Diagnosis and Treatment of Right Heart Failure in Pulmonary Vascular Diseases: A National Heart, Lung, and Blood Institute Workshop

Right ventricular dysfunction is a hallmark of advanced pulmonary vascular, lung parenchymal, and left heart disease, yet the underlying mechanisms that govern (mal)adaptation remain incompletely characterized. Owing to the knowledge gaps in our understanding of the right ventricle (RV) in health and disease, the National Heart, Lung, and Blood Institute (NHLBI) commissioned a working group to identify current challenges in the field. These included a need to define and standardize normal RV structure and function in populations; access to RV tissue for research purposes and the development of complex experimental platforms that recapitulate the in vivo environment; and the advancement of imaging and invasive methodologies to study the RV within basic, translational, and clinical research programs. Specific recommendations were provided, including a call to incorporate precision medicine and innovations in prognosis, diagnosis, and novel RV therapeutics for patients with pulmonary vascular disease.

Cardiac index is associated with oxygenation in COVID-19 acute respiratory distress syndrome

Eleven participants with COVID-19 acute respiratory distress syndrome requiring mechanical ventilation underwent pulmonary artery catheterization for clinical indications. Clinical interventions or events concurrent with hemodynamic were recorded. Increased cardiac index was associated with worse hypoxemia. Modulation of cardiac index may improve hypoxemia in patients with COVID-19 acute respiratory distress syndrome.

Experimental design of the Effects of Dehydroepiandrosterone in Pulmonary Hypertension (EDIPHY) trial

Pulmonary arterial hypertension (PAH) remains life-limiting despite numerous approved vasodilator therapies. Right ventricular (RV) function determines outcome in PAH but no treatments directly target RV adaptation. PAH is more common in women, yet women have better RV function and survival as compared to men with PAH. Lower levels of the adrenal steroid dehydroepiandrosterone (DHEA) and its sulfate ester are associated with more severe pulmonary vascular disease, worse RV function, and mortality independent of other sex hormones in men and women with PAH. DHEA has direct effects on nitric oxide (NO) and endothelin-1 (ET-1) synthesis and signaling, direct antihypertrophic effects on cardiomyocytes, and mitigates oxidative stress. Effects of Dehydroepiandrosterone in Pulmonary Hypertension (EDIPHY) is an on-going randomized double-blind placebo-controlled crossover trial of DHEA in men (n = 13) and pre- and post-menopausal women (n = 13) with Group 1 PAH funded by the National Heart, Lung and Blood Institute. We will determine whether orally administered DHEA 50 mg daily for 18 weeks affects RV longitudinal strain measured by cardiac magnetic resonance imaging, markers of RV remodeling and oxidative stress, NO and ET-1 signaling, sex hormone levels, other PAH intermediate end points, side effects, and safety. The crossover design will elucidate sex-based phenotypes in PAH and whether active treatment with DHEA impacts NO and ET-1 biosynthesis. EDIPHY is the first clinical trial of an endogenous sex hormone in PAH. Herein we present the study’s rationale and experimental design.

Deep RNA Sequencing of Intensive Care Unit Patients with COVID-19

PURPOSE

COVID-19 has impacted millions of patients across the world. Molecular testing occurring now identifies the presence of the virus at the sampling site: nasopharynx, nares, or oral cavity. RNA sequencing has the potential to establish both the presence of the virus and define the host's response in COVID-19.

METHODS

Single center, prospective study of patients with COVID-19 admitted to the intensive care unit where deep RNA sequencing (>100 million reads) of peripheral blood with computational biology analysis was done. All patients had positive SARS-CoV-2 PCR. Clinical data was prospectively collected.

RESULTS

We enrolled fifteen patients at a single hospital. Patients were critically ill with a mortality of 47% and 67% were on a ventilator. All the patients had the SARS-CoV-2 RNA identified in the blood in addition to RNA from other viruses, bacteria, and archaea. The expression of many immune modulating genes, including PD-L1 and PD-L2, were significantly different in patients who died from COVID-19. Some proteins were influenced by alternative transcription and splicing events, as seen in HLA-C, HLA-E, NRP1 and NRP2. Entropy calculated from alternative RNA splicing and transcription start/end predicted mortality in these patients.

CONCLUSIONS

Current upper respiratory tract testing for COVID-19 only determines if the virus is present. Deep RNA sequencing with appropriate computational biology may provide important prognostic information and point to therapeutic foci to be precisely targeted in future studies.

TAKE HOME MESSAGE

Deep RNA sequencing provides a novel diagnostic tool for critically ill patients. Among ICU patients with COVID-19, RNA sequencings can identify gene expression, pathogens (including SARS-CoV-2), and can predict mortality.

TWEET

Deep RNA sequencing is a novel technology that can assist in the care of critically ill COVID-19 patients & can be applied to other 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.

Prevalence and risk factors of pulmonary hypertension among adult patients with HIV infection in Ethiopia

Globally, non-communicable diseases are increasing in people living with HIV. Pulmonary hypertension is a rare non-communicable disease in people living with HIV with a reported prevalence of <1%. However, data on pulmonary hypertension in people living with HIV from Africa are scarce and are non-existent from Ethiopia. This study aimed to examine the prevalence and severity of echocardiographic pulmonary hypertension and risk factors associated with pulmonary hypertension in people living with HIV in Ethiopia. A total of 315 consecutive adult people living with HIV followed at the Tikur Anbessa Specialized Hospital HIV Referral Clinic were enrolled from June 2018 to February 2019. Those with established pulmonary hypertension of known causes were excluded. A structured questionnaire was used to collect data on demographics, respiratory symptoms, physical findings, physician-diagnosed lung disease, and possible risk factors. Pulmonary hypertension was defined by a tricuspid regurgitant velocity of ≥2.9 m/sec on transthoracic echocardiography. A tricuspid regurgitant velocity ≥3.5, which translates into a pulmonary arterial pressure/right ventricular systolic pressure of ≥50 mmHg, was considered moderate-to-severe pulmonary hypertension. The mean age of the participants was 44.5 ± 9.8 years and 229 (72.7%) were females. Pulmonary hypertension was diagnosed in 44 (14.0%) of participants, of whom 9 (20.5%) had moderate-to-severe disease. In those with pulmonary hypertension, 17 (38.6%) were symptomatic: exertional dyspnea, cough, and leg swelling were seen in 12 (27.3%), 9 (20.5%), and 4 (9.1%), respectively. There was no significant difference in those with pulmonary hypertension compared to those without the disease by gender, cigarette smoking, previous history of pulmonary tuberculosis treatment, physician-diagnosed chronic obstructive pulmonary disease or bronchial asthma, duration of anti-retroviral therapy therapy or anti-retroviral regimen type. Pulmonary hypertension looks to be a frequent complication in people living with HIV in Ethiopia and is often associated with significant cardiopulmonary symptoms. Further studies using right heart catheterization are needed to better determine the etiology and prevalence of pulmonary hypertension in people living with HIV in Ethiopia compared to other countries.

Mesenchymal Stem Cell Extracellular Vesicles Reverse Sugen/Hypoxia Pulmonary Hypertension in Rats

Mesenchymal stem cell extracellular vesicles attenuate pulmonary hypertension, but their ability to reverse established disease in larger animal models and the duration and mechanism(s) of their effect are unknown. We sought to determine the efficacy and mechanism of mesenchymal stem cells' extracellular vesicles in attenuating pulmonary hypertension in rats with Sugen/hypoxia-induced pulmonary hypertension. Male rats were treated with mesenchymal stem cell extracellular vesicles or an equal volume of saline vehicle by tail vein injection before or after subcutaneous injection of Sugen 5416 and exposure to 3 weeks of hypoxia. Pulmonary hypertension was assessed by right ventricular systolic pressure, right ventricular weight to left ventricle + septum weight, and muscularization of peripheral pulmonary vessels. Immunohistochemistry was used to measure macrophage activation state and recruitment to lung. Mesenchymal stem cell extracellular vesicles injected before or after induction of pulmonary hypertension normalized right ventricular pressure and reduced right ventricular hypertrophy and muscularization of peripheral pulmonary vessels. The effect was consistent over a range of doses and dosing intervals and was associated with lower numbers of lung macrophages, a higher ratio of alternatively to classically activated macrophages (M2/M1 = 2.00 ± 0.14 vs. 1.09 ± 0.11; P < 0.01), and increased numbers of peripheral blood vessels (11.8 ± 0.66 vs. 6.9 ± 0.57 vessels per field; P < 0.001). Mesenchymal stem cell extracellular vesicles are effective at preventing and reversing pulmonary hypertension in Sugen/hypoxia pulmonary hypertension and may offer a new approach for the treatment of pulmonary arterial hypertension.

COVID-19 critical illness pathophysiology driven by diffuse pulmonary thrombi and pulmonary endothelial dysfunction responsive to thrombolysis

Patients with severe COVID-19 disease have been characterized as having the acute respiratory distress syndrome (ARDS). Critically ill COVID-19 patients have relatively well-preserved lung mechanics despite severe gas exchange abnormalities, a feature not consistent with classical ARDS but more consistent with pulmonary vascular disease. Many patients with severe COVID-19 also demonstrate markedly abnormal coagulation, with elevated d-dimers and higher rates of venous thromboembolism. We present four cases of patients with severe COVID-19 pneumonia with severe respiratory failure and shock, with evidence of markedly elevated dead-space ventilation who received tPA. All showed post treatment immediate improvements in gas exchange and/or hemodynamics. We suspect that severe COVID-19 pneumonia causes respiratory failure via pulmonary microthrombi and endothelial dysfunction. Treatment for COVID-19 pneumonia may warrant anticoagulation for milder cases and thrombolysis for more severe disease.

COVID-19 Critical Illness Pathophysiology Driven by Diffuse Pulmonary Thrombi and Pulmonary Endothelial Dysfunction Responsive to Thrombolysis

Patients with severe COVID-19 disease have been characterized as having the acute respiratory distress syndrome (ARDS). Critically ill COVID-19 patients have relatively well-preserved lung mechanics despite severe gas exchange abnormalities, a feature not consistent with classical ARDS but more consistent with pulmonary vascular disease. Patients with severe COVID-19 also demonstrate markedly abnormal coagulation, with elevated D-dimers and higher rates of venous thromboembolism. We present five cases of patients with severe COVID-19 pneumonia with severe respiratory failure and shock, with evidence of markedly elevated dead-space ventilation who received tPA. All showed post treatment immediate improvements in gas exchange and/or hemodynamics. We suspect that severe COVID-19 pneumonia causes respiratory failure via pulmonary microthrombi and endothelial dysfunction. Treatment for COVID-19 pneumonia may warrant anticoagulation for milder cases and thrombolysis for more severe disease.

Culture of pulmonary artery endothelial cells from pulmonary artery catheter balloon tips: considerations for use in pulmonary vascular disease

Endothelial dysfunction is a hallmark of pulmonary arterial hypertension (PAH) but there are no established methods to study pulmonary artery endothelial cells (PAECs) from living patients. We sought to culture PAECs from pulmonary artery catheter (PAC) balloons used during right-heart catheterisation (RHC) to characterise successful culture attempts and to describe PAEC behaviour.PAECs were grown in primary culture to confluence and endothelial cell phenotype was confirmed. Standard assays for apoptosis, migration and tube formation were performed between passages three to eight. We collected 49 PAC tips from 45 subjects with successful PAEC culture from 19 balloons (39%).There were no differences in subject demographic details or RHC procedural details in successful versus unsuccessful attempts. However, for subjects who met haemodynamic criteria for PAH, there was a higher but nonsignificant (p=0.10) proportion amongst successful attempts (10 out of 19, 53%) versus unsuccessful attempts (nine out of 30, 30%). A successful culture was more likely in subjects with a lower cardiac index (p=0.03) and higher pulmonary vascular resistance (p=0.04). PAECs from a subject with idiopathic PAH were apoptosis resistant compared to commercial PAECs (p=0.04) and had reduced migration compared to PAECs from a subject with portopulmonary hypertension with high cardiac output (p=0.01). PAECs from a subject with HIV-associated PAH formed fewer (p=0.01) and shorter (p=0.02) vessel networks compared to commercial PAECs.Sustained culture and characterisation of PAECs from RHC balloons is feasible, especially in PAH with high haemodynamic burden. This technique may provide insight into endothelial dysfunction during PAH pathogenesis.