Severe Pulmonary Arterial Hypertension Research Articles

Ethyl pyruvate alleviates pulmonary arterial hypertension via PI3K-Akt signaling.

Pulmonary arterial hypertension (PAH) is a pathophysiological syndrome that is extremely difficult to manage, and there is currently no effective treatment. We want to elucidate the therapeutic effect of ethyl pyruvate (EP) on PAH and its possible mechanism. Pulmonary artery endothelial cells (PAECs) were cultured in conventional low-oxygen environments, and cellular proliferation was monitored after treatment with EP. Expression of p-PI3K/Akt, LC3-II, and Beclin-1 was detected by Western blot. After hyperkinetic PAH rabbits' models were treated with EP, hemodynamic data were collected. Right ventricular hypertrophy and pulmonary vascular remodeling were evaluated. Expression of p-PI3K/Akt, LC3-II, and Beclin-1 protein was also detected after using autophagy inhibitor and agonists. We found that EP could inhibit PAECs proliferation. After EP treatment, expression of p-PI3K/Akt was upregulated in vitro and in vivo. LC3-II and Beclin-1 were inhibited and their expression was lower after autophagy inhibitor was given, while after administration of autophagy agonists, their expression was higher than that in the EP alone group. Besides, EP attenuated PAH, and right ventricular hypertrophy and pulmonary vascular remodeling were also reversed. EP can reduce PAH and reverse vascular remodeling which is associated with inhibition of autophagy in PAECs based on PI3K-Akt signaling pathway. The results of this study can provide surgical opportunities for patients with severe PAH caused by congenital heart disease in clinical cardiovascular surgery.

STAT3 phosphorylation at Tyr705 affects DRP1 (dynamin-related protein 1) controlled-mitochondrial fission during the development of apoptotic-resistance in pulmonary arterial endothelial cells.

The apoptosis-resistant pulmonary arterial endothelial cells (PAECs) are known to be major players in the pulmonary remodeling of pulmonary arterial hypertension (PAH) and exhibit an abnormal metabolic profile with mitochondrial dysfunction. Mitochondrial fission has been shown to regulate the apoptosis of several cell types, but this is largely unexplored in the PAECs. The roles of mitochondrial fission control by Dynamin related protein-1 (DRP1) in the development of PAECs apoptosis suppression were investigated in present study and the potential mechanisms behind this were furtherly explored. The mitochondrial morphology was investigated in PAECs from PAH rats with the pulmonary plexiform lesions, and the relations of it with DRP1 expression and apoptosis were furtherly identified in apoptosis-resistant PAECs induced by hypoxia. PAECs were isolated from rats with severe PAH and from normal subjects, the apoptotic-resistant PAECs were induced by hypoxia. DRP1 gene knockdown was achieved via DRP1-siRNA, DRP1 and STAT3 phosphorylation were blocked using its inhibitors, respectively. Apoptosis was analyzed by flow cytometry, and mitochondrial morphology was investigated by transmission electron microscope and confocal microscopy. The PAECs isolated from PAH rats with the pulmonary plexiform-like lesions and displayed lower apoptotic rate with increased DRP1 expression and mitochondrial fragmentation. In addition, similar observations were achieved in apoptosis-resistant PAECs induced by hypoxia. Targeting DRP1 using siRNA and pharmacologic blockade prevented the mitochondrial fission and subsequent apoptotic resistance in PAECs under hypoxia. Mechanistically, STAT3 phosphorylation at Tyr705 was shown to be activated in both PAH and hypoxia-treated PAECs, leading to the regulation of DRP1 expression. Of importance, targeting STAT3Tyr705 phosphorylation prevented DRP1 disruption on apoptosis in PAECs under hypoxia. These data indicated that STAT3 phosphorylation at Tyr705 impacted DRP1-controlled mitochondrial fission during the development of apoptosis-resistance in PAECs, suggesting mitochondrial dynamics may represent a therapeutic target for PAH.

Surgical anastomosis of vertical vein to left atrial appendage: A case report of technical aspects

Management of partial anomalous pulmonary venous connection (PAPVC) differs significantly between the defect on the left side, which is adjacent to left atrial appendage, and that on the right one adjacent to the interatrial septum. Here, we report two patients operated at our center. The first case is an adult diagnosed with the left-sided PAPVC draining to an innominate vein through a left-sided vertical vein, and with a large ostium secundum atrial septal defect. The second case is a neonate with mixed-type total anomalous pulmonary venous connection with all right pulmonary veins opening into the coronary sinus, and all the left pulmonary veins connecting to the innominate vein through a left-sided vertical vein. Both patients experienced severe pulmonary arterial hypertension, necessitating surgical treatment involving disconnection of the vertical vein from its junction, or, ligation of the vertical vein-innominate vein junction, coupled with its redirection to the left atrial appendage. We employed different surgical procedures on these patients, given the distinct age difference, intending to anastomose their respective vertical veins to the adjacent left atrial appendage. In this report, the technical aspects of anastomosing vertical vein to left atrial appendage, to avoid pulmonary venous obstruction in these two patients, are discussed.

Application of homocysteine as a non-invasive and effort-free measurements for risk assessment of patients with pulmonary hypertension.

Current guideline-recommended multiparameters used to assess the risk levels of pulmonary arterial hypertension (PAH) are invasive hemodynamic measurements or effort-dependent exercise tests. Serum natriuretic peptide is only one kind of effort-free biomarker that has been adopted for risk assessment. This study aimed to investigate the application of homocysteine as a non-invasive and effort-free measurement for the risk assessment of patients with PAH. Samples of 50 patients diagnosed with PAH via right heart catheterization were obtained, and the patients were divided into low-, intermediate- and high-risk groups for further analysis. Additionally, serum N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) and homocysteine levels of monocrotaline (MCT)-induced PAH rats were analyzed at each week with progressed severity of PAH, and they were sacrificed on day 28 with pathology being assessed. Hyperhomocysteinemia was an independent predictor (odds ratio [OR]: 1.256; 95% confidence interval [CI]: 1.002-1.574) and showed a linear correlation with NT-proBNP. Hyperhomocysteinemia could discriminate between low/intermediate and high-risk levels in PAH with a cut-off value in 12 μmol/L. Moreover, the elevated homocysteine levels by weeks in MCT rats also demonstrated the association between homocysteine and the severity of PAH. Homocysteine can be a non-invasive and effort-free risk assessment for patients with pulmonary hypertension. Homocysteine level had a linear correlation with NT-proBNP level, and patients with hyperhomocysteinemia had a higher risk level, higher NT-proBNP level, and decreased lower diffusing capacity for carbon monoxide. The correlation between homocysteine level and PAH severity was also demonstrated in MCT rats.

Neutrophil extracellular traps promote proliferation of pulmonary smooth muscle cells mediated by CCDC25 in pulmonary arterial hypertension

BackgroundPrevious studies have indicated that neutrophil extracellular traps (NETs) play a pivotal role in pathogenesis of pulmonary arterial hypertension (PAH). However, the specific mechanism underlying the impact of NETs on pulmonary artery smooth muscle cells (PASMCs) has not been determined. The objective of this study was to elucidate underlying mechanisms through which NETs contribute to progression of PAH.MethodsBioinformatics analysis was employed in this study to screen for potential molecules and mechanisms associated with occurrence and development of PAH. These findings were subsequently validated in human samples, coiled-coil domain containing 25 (CCDC25) knockdown PASMCs, as well as monocrotaline-induced PAH rat model.ResultsNETs promoted proliferation of PASMCs, thereby facilitating pathogenesis of PAH. This phenomenon was mediated by the activation of transmembrane receptor CCDC25 on PASMCs, which subsequently activated ILK/β-parvin/RAC1 pathway. Consequently, cytoskeletal remodeling and phenotypic transformation occur in PASMCs. Furthermore, the level of NETs could serve as an indicator of PAH severity and as potential therapeutic target for alleviating PAH.ConclusionThis study elucidated the involvement of NETs in pathogenesis of PAH through their influence on the function of PASMCs, thereby highlighting their potential as promising targets for the evaluation and treatment of PAH.

(1271) - Bilateral Lung Transplantation Combining Pulmonary Artery Reconstruction for Giant Pulmonary Artery Aneurysm with Severe Pulmonary Artery Hypertension

(1271) - Bilateral Lung Transplantation Combining Pulmonary Artery Reconstruction for Giant Pulmonary Artery Aneurysm with Severe Pulmonary Artery Hypertension

Empowering Little Fighters: Post-Cardiotomy Pediatric ECMO and the Journey to Recovery.

Extra Corporeal Membrane Oxygenation (ECMO) has long been used for cardiorespiratory support in the immediate post-paediatric cardiac surgery period with a 2-3% success as per the ELSO registry. Success in recovery depends upon the optimal delivery of critical care to paediatric patients and a comprehensive healthcare team. The survival benefit of children placed on central veno arterial (VA) ECMO following elective cardiac surgeries for congenital heart disease (n = 672) was studied in a cohort of 29 (4.3%) cases from the period of Jan 2018 to Dec 2022 in our cardiac surgical centre. Indications for placing these patients on central VA ECMO included inability to wean from cardiopulmonary bypass (CPB), low cardiac output syndrome, severe pulmonary arterial hypertension, significant bleeding, anaphylaxis, respiratory failure and severe pulmonary edema. The mean time to initiation of ECMO was less than 5 h and the mean duration of ECMO support was 56 h with a survival rate of 58.3%. Amongst perioperative complications, sepsis and arrhythmia on ECMO were found to be negatively associated with survival. Improvements in the pH, PaO2 levels and serum lactate levels after initiation of ECMO were associated with survival benefits. The early initiation of ECMO for paediatric cardiotomies could be a beacon of hope for families and medical teams confronting these challenging situations. Improvement in indicators of adequate perfusion and ventricular recoveries like pH and serum lactate and absence of arrhythmia and sepsis are associated with good outcomes.

Pulmonary hypertension and metabolic disorders

This review presents current data regarding the relationship between hyperuricemia, obesity, diabetes mellitus, lipid disorders and pulmonary arterial hypertension (PAH), chronic thromboembolic pulmonary hypertension (CTEPH). Hyperuricemia is associated with a higher risk of developing of PAH, worse prognosis of PAH and greater severity of the patient's condition. Obesity leads to the development of pro-inflammatory and vasoconstrictor effects, hypoxia, which contributes to the progression of PH, however, the survival rate of patients with PH and overweight or obesity is higher than with normal or reduced body weight. Diabetes mellitus and concomitant insulin resistance are associated with a high risk of hospitalization for right ventricular heart failure and mortality. The presence of PAH is associated with lower values of total cholesterol, low-density lipoprotein cholesterol (LDL-C), triglycerides, and probably high-density lipoprotein cholesterol (HDL-C). At the same time, higher levels of LDL-С and HDL-С in PAH and CTEPH determine a better prognosis of the disease.All metabolic disorders considered have common mechanisms of influence on PH. Further study of their pathogenetic basis will make it possible to develop unified approaches to methods of their correction in patients with various types of pulmonary hypertension.

Autologous Reconstruction of Anomalous Origin of a Right Pulmonary Artery From the Aorta.

Anomalous origin of a pulmonary artery branch from the aorta is a rare congenital anomaly in which one of the pulmonary arteries arises from the aorta. These patients require early surgery to prevent development of severe irreversible pulmonary arterial hypertension. Multiple techniques have been described for repair of this condition. In this report, we describe a different technique compared with previously described procedures and discuss its advantages.

Mendelian Randomization Study With Clinical Follow-Up Links Metabolites to Risk and Severity of Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) exhibits phenotypic heterogeneity and variable response to therapy. The metabolome has been implicated in the pathogenesis of PAH, but previous works have lacked power to implicate specific metabolites. Mendelian randomization (MR) is a method for causal inference between exposures and outcomes. Using genome-wide association study summary statistics, we implemented MR analysis to test for potential causal relationships between serum concentration of 575 metabolites and PAH. Five metabolites were causally associated with the risk of PAH after multiple testing correction. Next, we measured serum concentration of candidate metabolites in an independent clinical cohort of 449 patients with PAH to check whether metabolite concentrations are correlated with markers of disease severity. Of the 5 candidates nominated by our MR work, serine was negatively associated and homostachydrine was positively associated with clinical severity of PAH via direct measurement in this independent clinical cohort. Finally we used conditional and orthogonal approaches to explore the biology underlying our lead metabolites. Rare variant burden testing was carried out using whole exome sequencing data from 578 PAH cases and 361 675 controls. Multivariable MR is an extension of MR that uses a single set of instrumental single-nucleotide polymorphisms to measure multiple exposures; multivariable MR is used to determine interdependence between the effects of different exposures on a single outcome. Rare variant analysis demonstrated that loss-of-function mutations within activating transcription factor 4, a transcription factor responsible for upregulation of serine synthesis under conditions of serine starvation, are associated with higher risk for PAH. Homostachydrine is a xenobiotic metabolite that is structurally related to l-proline betaine, which has previously been linked to modulation of inflammation and tissue remodeling in PAH. Our multivariable MR analysis suggests that the effect of l-proline betaine is actually mediated indirectly via homostachydrine. Our data present a method for study of the metabolome in the context of PAH, and suggests several candidates for further evaluation and translational research.

Feasibility of Treat and Repair Strategy in Congenital Heart Defects With Pulmonary Arterial Hypertension

BackgroundA treatment strategy for congenital heart defects with moderate to severe pulmonary arterial hypertension (PAH) has not been established. ObjectivesThe purpose of this study was to identify patients in whom a treat and repair strategy was considered and to examine pretreatment variables associated with successful defect repair. MethodsPatients with atrial or ventricular septal defect and PAH (pulmonary vascular resistance [PVR] ≥ 5 Wood units) eligible for the treat and repair strategy were included. Hemodynamics among pretreatment, pre-repair, and post-defect repair were compared. Clinical outcomes in patients with or without defect repair were also compared. Clinical outcomes included all-cause death, hospitalization for worsening pulmonary hypertension, and lung transplantation. ResultsAmong 25 eligible for the treat and repair strategy, 20 underwent successful repair (repaired group) and 5 did not have a repair (unrepaired group). In the repaired group, PVR significantly decreased from 9.6 ± 2.6 WU at pretreatment to 5.0 ± 3.4 pre-repair (ß coefficient −4.6 [95% CI: −5.9 to −3.3]). The pulmonary to systemic blood flow ratio (Qp/Qs) increased from 1.5 ± 0.6 at pretreatment to 2.4 ± 1.3 pre-repair (ß coefficient 0.9 [95% CI: 0.4-1.38]). In the unrepaired group, pretreatment PVR decreased with treatment; however, PVR remained elevated. Qp/Qs did not change between pretreatment and post-treatment. The repaired group had a better prognosis than the unrepaired group (HR 0.092 [95% CI: 0.009-0.905]). Pretreatment mean pulmonary artery pressure, PVR, Qp/Qs, and arterial oxygen saturations were associated with undergoing defect repair. ConclusionsIn this small cohort, a treat and repair strategy was successfully used in a significant proportion of the patients with congenital heart defects with moderate to severe PAH.

Combination of high-flow nasal oxygen and ketamine/dexmedetomidine sedation for diagnostic catheterization in a child with pulmonary arterial hypertension: a case report

Pulmonary hypertension is associated with significant risk of perioperative life-threatening events. We present a case of a 12-year-old child with severe pulmonary arterial hypertension who successfully underwent diagnostic cardiac catheterization under ketamine and dexmedetomidine sedation with the support of high-flow nasal oxygen. Ketamine and dexmedetomidine are reported to have minimal effect on pulmonary vasculature in children with pulmonary hypertension and can be safely used in this population along with its lack of respiratory depression. Positive pressure generated by high-flow nasal oxygen improves upper airway patency, prevents micro-atelectasis, and is shown to improve the effectiveness of ventilation and oxygenation in patients under sedation breathing spontaneously. The presented strategy may contribute to enhancing the safety and effectiveness of procedural sedation for children with life-threatening pulmonary hypertension.

Noninvasive Monitoring of Severe Pulmonary Artery Hypertension in Atrial Septal Defect Patients: Role of Serum Bilirubin Combined with Uric Acid

Noninvasive Monitoring of Severe Pulmonary Artery Hypertension in Atrial Septal Defect Patients: Role of Serum Bilirubin Combined with Uric Acid

Management of Pulmonary Hypertension during Pregnancy

Abstract: Pregnancy in patients with pulmonary arterial hypertension (PAH) is a high-risk condition associated with high morbidity and mortality. Patients with severe PAH are often advised against pregnancy. Still, those patients who pursue pregnancy require a dedicated and multidisciplinary approach since the progression of fetal growth will accompany significant hemodynamic changes, which can be challenging for patients with a poorly functioning right ventricle. In this article, we describe the approach to the unique cardiovascular, respiratory, hematologic, and social challenges that pregnant patients with PAH face throughout pregnancy. We discuss the impact of these physiologic changes on diagnostic studies commonly used in PAH and how to incorporate diagnostic data in making the diagnosis and risk stratifying pregnant patients with PAH. The pharmacologic challenges of pulmonary vasodilators in pregnancy are discussed as well. Pregnant patients with PAH are at particularly high risk of mortality around the time of delivery, and we discuss the multidisciplinary approach to the management of these patients, including the use of anesthesia, inotropic support, type of delivery, and postpartum care, providing clinicians with a practical approach to the management of this difficult condition.

Fatty acid metabolism promotes TRPV4 activity in lung microvascular endothelial cells in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a morbid disease characterized by significant lung endothelial cell (EC) dysfunction. Prior work has shown that microvascular endothelial cells (MVECs) isolated from animals with experimental PAH and patients with PAH exhibit significant abnormalities in metabolism and calcium signaling. With regards to metabolism, we and others have shown evidence of increased aerobic glycolysis and evidence of increased utilization of alternate fuel sources (such as fatty acids) in PAH EC. In the realm of calcium signaling, our prior work linked increased activity of the transient receptor potential vanilloid-4 (TRPV4) channel to increased proliferation of MVECs isolated from the Sugen/Hypoxia rat model of PAH (SuHx-MVECs). However, the relationship between metabolic shifts and calcium abnormalities was not clear. Specifically, whether shifts in metabolism were responsible for increasing TRPV4 channel activity in SuHx-MVECs was not known. In this study, using human data, serum samples from SuHx rats, and SuHx-MVECs, we describe the consequences of increased MVEC fatty acid oxidation in PAH. In human samples, we observed an increase in long-chain fatty acid levels that was associated with PAH severity. Next, using SuHx rats and SuHx-MVECs, we observed increased intracellular levels of lipids. We also show that increasing intracellular lipid content increases TRPV4 activity, whereas inhibiting fatty acid oxidation normalizes basal calcium levels in SuHx-MVECs. By exploring the fate of fatty acid-derived carbons, we observed that the metabolite linking increased intracellular lipids to TRPV4 activity was β-hydroxybutyrate (BOHB), a product of fatty acid oxidation. Finally, we show that BOHB supplementation alone is sufficient to sensitize the TRPV4 channel in rat and mouse MVECs. Returning to humans, we observe a transpulmonary BOHB gradient in human patients with PAH. Thus, we establish a link between fatty acid oxidation, BOHB production, and TRPV4 activity in MVECs in PAH. These data provide new insight into metabolic regulation of calcium signaling in lung MVECs in PAH.NEW & NOTEWORTHY In this paper, we explore the link between metabolism and intracellular calcium levels in microvascular endothelial cells (MVECs) in pulmonary arterial hypertension (PAH). We show that fatty acid oxidation promotes sensitivity of the transient receptor potential vanilloid-4 (TRPV4) calcium channel in MVECs isolated from a rodent model of PAH.

Safety of Macitentan for the Treatment of Portopulmonary Hypertension: Real-World Evidence from the Combined OPUS/OrPHeUS Studies.

Portopulmonary hypertension (PoPH) carries a worse prognosis than other forms of pulmonary arterial hypertension (PAH). Data regarding use of PAH-specific therapies in patients with PoPH are sparse as they are usually excluded from clinical trials. This analysis describes patient characteristics, treatment patterns, outcomes, and safety profiles in patients with PoPH newly initiating macitentan in the USA using the OPUS/OrPHeUS combined dataset. OPUS was a prospective, US, multicenter, observational drug registry (April 2014-June 2020); OrPHeUS was a retrospective, US, multicenter chart review (October 2013-March 2017). Additional information regarding patients' liver disease was retrospectively collected for patients with PoPH in OPUS. The OPUS/OrPHeUS dataset included 206 patients with PoPH (median age 58years; 52.4% female), with baseline cirrhosis and liver test abnormalities reported in 72.8% and 31.6% of patients respectively. Macitentan was initiated as combination therapy in 74.8% of patients and median (Q1, Q3) exposure to macitentan was 11.9 (3.1, 26.0) months. One-year Kaplan-Meier estimates (95% confidence limit, CL) of patients free from all-cause hospitalization and survival were 48.6% (40.7, 56.0) and 82.2% (75.1, 87.4). Of the 96 patients with PoPH in OPUS, 29.2% were classified as in need of liver transplant due to underlying liver disease during the study; transplant waitlist registration was precluded because of PAH severity for 32.1% and 17.9% were transplanted. Hepatic adverse events (HAE) were experienced by 49.0% of patients; the most common being increased bilirubin (16.0%), ascites (7.3%), and hepatic encephalopathy (5.8%); 1.5% and 21.8% of patients discontinued macitentan as a result of HAE and non-hepatic adverse events. There were no unexpected safety findings in patients with PoPH treated with macitentan. These data add to the evidence supporting the safety and tolerability of macitentan in patients with PoPH. A graphical abstract is available with this article. OPsumit® Users Registry (OPUS): NCT02126943; OPsumit® Historical Users cohort (OrPHeUS): NCT03197688; www. gov .

Diagnostic Value of Serum Galectin-3 Binding Protein Level in Patients with Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) still lacks effective biomarkers to assist in its diagnosis and prognosis. Galectin-3 binding protein (Gal-3BP) plays a role in immune and inflammatory diseases. This study aimed to evaluate Gal-3BP as a prognostic and predictive factor in patients with PAH. From January 2017 to December 2019, we enrolled 167 consecutive PAH patients and 58 healthy controls. Right heart catheterization (RHC) was used to diagnose PAH. Serum Gal-3BP levels were measured by high-sensitivity human enzyme-linked immunosorbent assay (ELISA). Serum Gal-3BP levels in the PAH group were significantly higher compared with the control group (4.87±2.09 vs 2.22±0.86 μg/mL, p<0.001). Gal-3BP level was correlated with several hemodynamic parameters obtained from RHC (p<0.001). Multivariate linear regression analysis showed that Gal-3BP was a risk factor for PAH (odds ratio (OR)=2.947, 95% CI: 1.821-4.767, p<0.001). The optimal cut-off value of serum Gal-3BP level for predicting PAH was 2.89 μg/mL (area under the curve (AUC)=0.860, 95 % CI: 0.811-0.910, p<0.001). Kaplan-Meier analysis showed that Gal-3BP levels above the median (4.87 μg/mL) were associated with an increased risk of death in patients with PAH (hazard ratio (HR)=8.868, 95 % CI: 3.631-21.65, p<0.0001). Cox multivariate risk regression analysis showed that Gal-3BP was a risk factor for death in PAH patients (HR=2.779, 95 % CI: 1.823-4.237, p<0.001). Serum Gal-3BP levels were increased in patients with PAH, and levels of Gal-3BP were associated with the severity of PAH. Gal-3BP might have predictive value for the diagnosis and prognosis of PAH.

Safety of inhaled nitric oxide withdrawal in severe chronic pulmonary hypertension.

Inhaled nitric oxide (iNO) is a potent and selective pulmonary vasodilator with a safety concern due to rebound pulmonary hypertension (PH) associated with its withdrawal. We report short-term pulsed iNO in patients with severe pulmonary arterial hypertension (PAH) and nonoperable chronic thromboembolic PH (nCTEPH). This is a retrospective analysis of 33 patients: 22 with PAH and 11 with nCTEPH. We assessed hemodynamic, echocardiographic, and other noninvasive variables to evaluate safety and efficacy of iNO. We performed an iNO withdrawal test during right heart catheterization and after 3 days of iNO treatment. iNO significantly improved all variables examined in 22 patients with PAH and 11 with nCTEPH. Two patterns of response were observed after sudden iNO withdrawal. Twenty-nine patients (88%) showed minimal hemodynamic, oxygenation and clinical changes. Four patients (12%) had a reduction in cardiac index ≥20% and PaO2 ≥ 5%, three patients did not show clinical deterioration, and one patient developed hemodynamic collapse that needed iNO administration. This retrospective study suggests that short-term iNO improves hemodynamics and clinical conditions in some patients with PAH an nCTPEH. However, pulsed iNO withdrawal PH rebound could be a serious concern in these patients. Given the lack of evidence, we do not recommend the use of pulsed iNO in the treatment of patients with chronic PH.

The significance of dynamic monitoring plasma TMAO level in pulmonary arterial hypertension - a cohort study.

Gut microbiota assumes an essential role in the development and progression of pulmonary arterial hypertension (PAH). Trimethylamine N-oxide (TMAO), a gut microbiota-dependent metabolite, is correlated with the prognosis of patients with PAH. However, the correlation between changes in TMAO (ΔTMAO) and the prognosis of PAH remains elusive. To investigate the association between ΔTMAO and prognosis of PAH, and explore whether dynamic assessment of TMAO level was superior to measurement at a single time point in predicting prognosis. Single-center cohort study. Consecutive patients diagnosed with PAH and had at least two TMAO measurements taken from May 2019 to June 2020 were eligible. The outcome events of this study were defined as adverse clinical events. A total of 117 patients with PAH who had two TMAO measurements and follow-up were included in this study. Patients with ΔTMAO ⩾1.082 μmol/L had over four times increased risk of adverse clinical events than their counterparts after adjusting for confounders [hazard ratio (HR) 4.050, 95% confidence interval (CI): 1.468-11.174; p = 0.007]. Patients with constant high TMAO levels at both time points had the highest risk of adverse clinical events compared with patients with constant low TMAO levels (HR 3.717, 95% CI: 1.627-8.492; p = 0.002). ΔTMAO was also associated with changes in parameters reflecting PAH severity (p < 0.05). Changes in TMAO were independently correlated with prognosis in patients with PAH, irrespective of baseline level of TMAO. ΔTMAO also correlated with alteration in disease severity. Repeated assessment of TMAO level contributes to better identification of patients with increased risk of adverse clinical events.

Outcomes and risk assessment in pulmonary veno-occlusive disease.

Pulmonary veno-occlusive disease (PVOD) is a rare and severe subtype of pulmonary arterial hypertension (PAH). Although European Society of Cardiology/European Respiratory Society (ESC/ERS) guidelines advise assessing PAH severity at baseline and during follow-up, no existing risk assessment methods have been validated for PVOD. This study aimed to identify prognostic factors, examine the impact of treatment strategies and evaluate risk assessment methods for PVOD patients. The study analysed all incident PVOD patients included in the French Pulmonary Hypertension Registry between 2006 and 2021. Survival was assessed based on initial treatment strategy and risk status and compared to a matched (age, sex, pulmonary vascular resistance) PAH group. Six risk assessment methods (number of four low-risk and three noninvasive low-risk variables, ESC/ERS guidelines three-strata and four-strata models, REVEAL 2.0 and Lite 2) were applied at baseline and early follow-up, and their accuracy was compared using Harrell's c-statistic. Among the 327 included PVOD patients, survival rates at 1, 3 and 5 years were 86%, 50% and 27%, respectively. Multivariate analysis showed that only 6-min walk distance was associated with survival, with no significant difference based on initial treatment strategy. All six risk assessment methods could discriminate mortality risk, and the ESC/ERS four-strata model was the most accurate at both baseline and follow-up (C-index 0.64 and 0.74). PVOD survival rates were consistently lower than PAH when comparing baseline risk status using the ESC/ERS four-strata model. PVOD is associated with poor outcomes, and initial treatment strategies do not significantly affect survival. Risk assessment methods can be useful in predicting survival for PVOD patients.