Pulmonary vasodilator therapies are of no benefit in pulmonary hypertension due to left heart disease: A meta-analysis

Effect of Acute Vasodilator Testing Using Oxygen in Pulmonary Hypertension Due to Left Heart Disease

BACKGROUND

Pulmonary vasodilators, including oxygen, have not shown consistent beneficial effects on pulmonary hypertension due to valvular heart disease (PH-VHD). Therefore, the study aimed to assess the effect of 100% fractional inspiration of oxygen (FiO2) on pulmonary and systemic hemodynamics in patients with combined pre- and post-capillary pulmonary hypertension (CpcPH) and isolated post-capillary pulmonary hypertension (IpcPH) due to PH-VHD.

METHODS

This prospective study was conducted among patients with PH-VHD undergoing mitral or aortic valve replacement or repair. The study was conducted after induction of anesthesia and pulmonary artery catheterization. Cardiac output was obtained using thermodilution and all direct, and derived hemodynamic variables were obtained at 30% and 100% FiO2. The patients were stratified a priori into responders {(≥10 mmHg fall in mean pulmonary artery pressure (MPAP)} and non-responders.

RESULTS

Fifty-seven patients completed the acute vasodilator test. The mean age and body mass index of the study population was 41.8 ± 14.1 years and 21.4 ± 4.6 kg/m2, respectively. There was a significant decrease in MPAP (40.77 ± 12.07 mmHg vs 36.74 ± 13.3 mmHg; P < .001) and pulmonary vascular resistance (PVR) {(median; Interquartile range (IQR); 388; 371 vs 323; 362 dynes sec.cm-5; P < .001) at 100% FiO2. Transpulmonary gradient (TPG) and diastolic pulmonary gradient (DPG) also decreased significantly (P < .001 and P < .001). Cardiac output did not change significantly. The magnitude of decrease in MPAP, PVR, TPG, DPG, and pulmonary artery compliance (PAC) between CpcPH and IpcPH was comparable. Responders did not show a significantly greater fall in MPAP, PVR, TPG, DPG, and PAC after surgery.

CONCLUSION

Hyperoxia may lead to reduction in MPAP and PVR in both hemodynamic phenotypes of PH-VHD. A larger sample size is required to support or refute the findings of this study.

Clinical-imaging-pathological correlation in pulmonary hypertension associated with left heart disease

Pulmonary hypertension (PH) is highly prevalent in patients with left heart disease (LHD) and negatively impacts prognosis. The most common causes of PH associated with LHD (PH-LHD) are left heart failure and valvular heart disease. In LHD, passive backward transmission of increased left-sided filling pressures leads to isolated post-capillary PH. Additional pulmonary vasoconstriction and remodelling lead to a higher vascular load and combined pre- and post-capillary PH. The increased afterload leads to right ventricular dysfunction and failure. Multimodality imaging of the heart plays a central role in the diagnostic work-up and follow-up of patients with PH-LHD. Echocardiography provides information about the estimated pulmonary artery pressure, morphology and function of the left and right side of the heart, and valvular abnormalities. Cardiac magnetic resonance imaging is the gold standard for volumetric measurements and provides myocardial tissue characterisation. Computed tomography of the thorax may show general features of PH and/or LHD and is helpful in excluding other PH causes. Histopathology reveals a spectrum of pre- and post-capillary vasculopathy, including intimal fibrosis, media smooth muscle cell hyperplasia, adventitial fibrosis and capillary congestion. In this paper, we provide an overview of clinical, imaging and histopathological findings in PH-LHD based on three clinical cases.

[Pulmonary hypertension associated with left heart disease (group 2)]

Pulmonary hypertension associated with left heart disease (PH-LHD) corresponds to group two of pulmonary hypertension according to clinical classification. Haemodynamically, this group includes isolated post-capillary pulmonary hypertension (IpcPH) and combined post- and pre-capillary pulmonary hypertension (CpcPH). PH-LHD is defined by an mPAP > 20 mmHg and a PAWP > 15 mmHg, pulmonary vascular resistance (PVR) with a cut-off value of 2 Wood Units (WU) is used to differentiate between IpcPH and CpcPH. A PVR greater than 5 WU indicates a dominant precapillary component. PH-LHD is the most common form of pulmonary hypertension, the leading cause being left heart failure with preserved (HFpEF) or reduced ejection fraction (HFmrEF, HFrEF), valvular heart disease and, less commonly, congenital heart disease. The presence of pulmonary hypertension is associated with increased symptom burden and poorer outcome across the spectrum of left heart disease. Differentiating between group 1 pulmonary hypertension with cardiac comorbidities and PH-LHD, especially due to HFpEF, is a particular challenge. Therapeutically, no general recommendation for the use of PDE5 inhibitors in HFpEF-associated CpcPH can be made at this time. There is currently no reliable rationale for the use of PAH drugs in IpcPH, nor is therapy with endothelin receptor antagonists or prostacyclin analogues recommended for all forms of PH-LHD.

Diagnosing post-capillary hypertension in patients with left heart disease: impact of new guidelines

BACKGROUND

In 2022, the definition of pulmonary hypertension (PH) in the presence of left heart disease was updated according to the new joint guidelines of the European Society of Cardiology (ESC) and the European Respiratory Society (ERS). The impact of the new ESC/ERS definition on the prevalence of post-capillary PH (pc-PH) and its subgroups of isolated post-capillary (Ipc-PH) and combined pre- and post-capillary PH (Cpc-PH) in patients with left heart disease is unclear.

METHODS

We retrospectively identified N = 242 patients with left heart disease with available data on right heart catheterisation (RHC) and cardiac magnetic resonance imaging (CMR). The proportion of pc-PH and its subgroups was calculated according to the old and new ESC/ERS PH definition. As the old definition did not allow the exact allocation of all patients with pc-PH into a respective subgroup, unclassifiable patients (Upc-PH) were regarded separately.

RESULTS

Seventy-six out of 242 patients had pc-PH according to the new ESC/ERS definitions, with 72 of these patients also meeting the criteria of the old definition. Using the old definition, 50 patients were diagnosed with Ipc-PH, 4 with Cpc-PH, and 18 with Upc-PH. Applying the new definition, Ipc-PH was diagnosed in 35 patients (4 newly), and Cpc-PH in 41 patients. No CMR parameter allowed differentiating between Ipc-PH and Cpc-PH, regardless of which guideline version was used.

CONCLUSION

Applying the new ESC/ERS 2022 guideline definitions mildly increased the proportion of patients diagnosed with pc-PH (+ 5.5%) but markedly increased Cpc-PH diagnoses. This effect was driven by the allocation of patients with formerly unclassifiable forms of post-capillary PH to the Cpc-PH subgroup and a significant shift of patients from the Ipc-PH to the Cpc-PH subgroup. Distribution of post-capillary pulmonary hypertension (pc-PH) subgroups according to the European Society of Cardiology/European Respiratory Society (ESC/ERS) PH guidelines from 2015 and 2022 in N = 242 patients with left heart disease.

Nanomedicine-mediated therapeutic approaches for pulmonary arterial hypertension

Nanomedicine has emerged as a field in which there are opportunities to improve the diagnosis, treatment and prevention of incurable diseases. Pulmonary arterial hypertension (PAH) is known as a severe and fatal disease affecting children and adults. Conventional treatments have not produced optimal effectiveness in treating this condition. Several reasons for this include drug instability, poor solubility of the drug and a shortened duration of pharmacological action. The present review focuses on new approaches for delivering anti-PAH drugs using nanotechnology with the aim of overcoming these shortcomings and increasing their efficacy. Solid-lipid nanoparticles, liposomes, metal-organic frameworks and polymeric nanoparticles have demonstrated advantages for the potential treatment of PAH, including increased drug bioavailability, drug solubility and accumulation in the lungs.

Pulmonary Hypertension Association's 2022 International Conference Scientific Sessions Overview

The considerable progress made in recent years in the diagnosis, risk stratification, and treatment of pulmonary hypertension was highlighted during the most recent edition of the Pulmonary Hypertension Association Scientific Sessions, which was held in Atlanta, Georgia from June 9 to 11, 2022, with the theme: Vision for the PHuture: The Evolving Science and Management of PH. Content presented over the 3-day conference focused on scientific and management updates since the last sessions were held in 2018 and included didactic talks, debates, and roundtable discussions across a broad spectrum of topics related to pulmonary hypertension. This article aims to summarize the key messages from each of the session talks.

Identifying key transcription factors and miRNAs coregulatory networks associated with immune infiltrations and drug interactions in idiopathic pulmonary arterial hypertension

BACKGROUND

The deregulated genetic factors are critically associated with idiopathic pulmonary arterial hypertension (IPAH) development and progression. However, the identification of hub-transcription factors (TFs) and miRNA-hub-TFs co-regulatory network-mediated pathogenesis in IPAH remains lacking.

METHODS

We used GSE48149, GSE113439, GSE117261, GSE33463, and GSE67597 for identifying key genes and miRNAs in IPAH. We used a series of bioinformatics approaches, including R packages, protein-protein interaction (PPI) network, and gene set enrichment analysis (GSEA) to identify the hub-TFs and miRNA-hub-TFs co-regulatory networks in IPAH. Also, we employed a molecular docking approach to evaluate the potential protein-drug interactions.

RESULTS

We found that 14 TFs encoding genes, including ZNF83, STAT1, NFE2L3, and SMARCA2 are upregulated, and 47 TFs encoding genes, including NCOR2, FOXA2, NFE2, and IRF5 are downregulated in IPAH relative to the control. Then, we identified the differentially expressed 22 hub-TFs encoding genes, including four upregulated (STAT1, OPTN, STAT4, and SMARCA2) and 18 downregulated (such as NCOR2, IRF5, IRF2, MAFB, MAFG, and MAF) TFs encoding genes in IPAH. The deregulated hub-TFs regulate the immune system, cellular transcriptional signaling, and cell cycle regulatory pathways. Moreover, the identified differentially expressed miRNAs (DEmiRs) are involved in the co-regulatory network with hub-TFs. The six hub-TFs encoding genes, including STAT1, MAF, CEBPB, MAFB, NCOR2, and MAFG are consistently differentially expressed in the peripheral blood mononuclear cells of IPAH patients, and these hub-TFs showed significant diagnostic efficacy in distinguishing IPAH cases from the healthy individuals. Moreover, we revealed that the co-regulatory hub-TFs encoding genes are correlated with the infiltrations of various immune signatures, including CD4 regulatory T cells, immature B cells, macrophages, MDSCs, monocytes, Tfh cells, and Th1 cells. Finally, we discovered that the protein product of STAT1 and NCOR2 interacts with several drugs with appropriate binding affinity.

CONCLUSIONS

The identification of hub-TFs and miRNA-hub-TFs co-regulatory networks may provide a new avenue into the mechanism of IPAH development and pathogenesis.

Emergency Veno-Arterial Extracorporeal Membrane Oxygenation for Pericardial Decompression Syndrome

Background

Pericardiocentesis is a therapeutic lifesaving intervention for patients presenting with cardiogenic shock due to pericardial effusion with signs of tamponade. Pericardial decompression syndrome (PDS) is a rare fatal complication that may occur after pericardiocentesis. Case Presentation. We report a case of a patient with idiopathic primary pulmonary hypertension who presented with massive pericardial effusion complicated with rapid hemodynamic and respiratory deterioration. Gradual therapeutic pericardiocentesis was done but progressive circulatory collapse occurred. Emergent veno-arterial extracorporeal membrane oxygenation (VA-ECMO) was applied. Echocardiography revealed severe right ventricle failure. Unfortunately, the patient developed acute progressive thrombocytopenia and bilaterally diffuse subarachnoid hemorrhage after 4 days of ECMO support.

Conclusions

Therapeutic pericardiocentesis can be occasionally fatal in cases of significant pulmonary hypertension with massive pericardial effusion when complicated by pericardial decompression syndrome. Acute significant thrombocytopenia may occur with VA-ECMO support resulting in fatal bleeding.

Management of Pulmonary Hypertension in Left Heart Disease

Pulmonary hypertension due to left heart diseases (PH-LHD) is the most prevalent form of pulmonary hypertension. It frequently complicates heart failure with reduced ejection fraction (HFrEF) or preserved ejection fraction (HFpEF) and negatively impacts prognosis, particularly when a precapillary component is present.

PH-LHD is distinctive from pulmonary arterial hypertension (PAH) even though both conditions may share some common characteristics. In addition, the mechanisms involved in the development of a precapillary component are yet to be fully clarified, in particular in PH due to HFpEF.

Several studies have been exploring PAH pathways as potential therapies for PH-LHD, but no PAH-approved drug has demonstrated efficacy in PH-LHD. Rather, some classes of drugs, such as endothelin-receptor antagonists or prostacycline-analogues, have been found to be harmful in patients with HF. Therefore, at present, the only established treatments for PH-LHD are those that target the heart as recommended in the international guidelines for HF. Based on current knowledge, off-label prescription of PAH-approved drugs in PH-LHD patients must be strongly discouraged.

Persisting burden and challenges of rheumatic heart disease

Rheumatic heart disease (RHD) is the result of episodes of acute rheumatic fever with valvular (and other cardiac) damage caused by an abnormal immune response to group A streptococcal infections, usually during childhood and adolescence. As a result of improved living conditions and the introduction of penicillin, RHD was almost eradicated in the developed world by the 1980s. However, being a disease of poverty, its burden remains disproportionately high in the developing world, despite being a fundamentally preventable disease. Rheumatic heart disease generates relatively little attention from the medical and science communities, in contrast to other common infectious problems (such as malaria, HIV, tuberculosis), despite the major cardiovascular morbidity/mortality burden imposed by RHD. This relative neglect and paucity of funding have probably contributed to limited fundamental medical advances in this field for over 50 years. Given the importance of prevention before the onset of major valvular damage, the main challenges for RHD prevention are improving social circumstances, early diagnosis, and effective delivery of antibiotic prophylaxis. Early identification through ultrasound of silent, subclinical rheumatic valve lesions could provide an opportunity for early intervention. Simple echocardiographic diagnostic criteria and appropriately trained personnel can be valuable aids in large-scale public health efforts. In addition, a better understanding of the immunogenic determinants of the disease may provide potential routes to vaccine development and other novel therapies.

Impact of targeted pulmonary arterial hypertension therapy in patients with combined post- and precapillary pulmonary hypertension

BACKGROUND

Combined post- and precapillary pulmonary hypertension (CpcPH) portends poor outcomes in pulmonary hypertension related to left heart disease (PH-LHD). While recent evidence does not support the use of targeted pulmonary arterial hypertension (PAH) therapy in PH-LHD, there is a lack of clinical data on their use in CpcPH. We evaluated the outcomes in patients with CpcPH treated with PAH therapies.

METHODS

Retrospectively, 50 patients meeting hemodynamic criteria of CpcPH and started on PAH-targeted drugs were identified. Fifty age- and gender-matched PAH patients were chosen as controls. We evaluated the change in 6-minute walk distance, World Health Organization functional class (FC), tricuspid annular plane systolic excursion, BNP or NT-proBNP, and pulmonary artery systolic pressure at 3, 6, 12, and 24 months of follow-up.

RESULTS

After adjusting for age and gender, there was no improvement in World Health Organization FC in CpcPH over 2 years (odds ratio of change to FC I/II 1.01, 95% CI: 0.98-1.04). There was no significant improvement in 6-minute walk distance (β coefficient 0.21, 95% CI: -0.98 to 1.4), reduction in BNP/NT-proBNP (β coefficient -12.16, 95% CI: -30.68 to 6.37), increase in tricuspid annular plane systolic excursion (β coefficient 0.074, 95% CI: 0.010-0.139), or decrease in pulmonary artery systolic pressure (0.996, 95% CI: 0.991-1.011) in CpcPH with therapy. There was higher mortality in CpcPH compared to PAH on treatment (24% vs 4%, P = .003).

CONCLUSIONS

There were no improvements in symptoms, exercise capacity, or echocardiographic parameters with PAH-targeted therapy in CpcPH. Further studies into potential treatments benefiting this population are needed.

Identification of Potential Biomarkers and Immune Infiltration Characteristics in Idiopathic Pulmonary Arterial Hypertension Using Bioinformatics Analysis

Objectives: Idiopathic pulmonary arterial hypertension (IPAH) is a rare but severe lung disorder, which may lead to heart failure and early mortality. However, little is known about the etiology of IPAH. Thus, the present study aimed to establish the differentially expressed genes (DEGs) between IPAH and normal tissues, which may serve as potential prognostic markers in IPAH. Furthermore, we utilized a versatile computational method, CIBERSORT to identify immune cell infiltration characteristics in IPAH.

Materials and Methods: The GSE117261 and GSE48149 datasets were obtained from the Gene Expression Omnibus database. The GSE117261 dataset was adopted to screen DEGs between IPAH and the control groups with the criterion of |log2 fold change| ≥ 1, adjusted P < 0.05, and to further explore their potential biological functions via Gene Ontology analysis, Kyoto Encyclopedia of Genes and Genomes Pathway analysis, and Gene Set Enrichment Analysis. Moreover, the support vector machine (SVM)-recursive feature elimination and the least absolute shrinkage and selection operator regression model were performed jointly to identify the best potential biomarkers. Then we built a regression model based on these selected variables. The GSE48149 dataset was used as a validation cohort to appraise the diagnostic efficacy of the SVM classifier by receiver operating characteristic (ROC) analysis. Finally, immune infiltration was explored by CIBERSORT in IPAH. We further analyzed the correlation between potential biomarkers and immune cells.

Results: In total, 75 DEGs were identified; 40 were downregulated, and 35 genes were upregulated. Functional enrichment analysis found a significantly enrichment in heme binding, inflammation, chemokines, cytokine activity, and abnormal glycometabolism. HBB, RNASE2, S100A9, and IL1R2 were identified as the best potential biomarkers with an area under the ROC curve (AUC) of 1 (95%CI = 0.937–1.000, specificity = 100%, sensitivity = 100%) in the discovery cohort and 1(95%CI = 0.805–1.000, specificity = 100%, sensitivity = 100%) in the validation cohort. Moreover, immune infiltration analysis by CIBERSORT showed a higher level of CD8+ T cells, resting memory CD4+ T cells, gamma delta T cells, M1 macrophages, resting mast cells, as well as a lower level of naïve CD4+ T cells, monocytes, M0 macrophages, activated mast cells, and neutrophils in IPAH compared with the control group. In addition, HBB, RNASE2, S100A9, and IL1R2 were correlated with immune cells.

Conclusion:HBB, RNASE2, S100A9, and IL1R2 were identified as potential biomarkers to discriminate IPAH from the control. There was an obvious difference in immune infiltration between patient with IPAH and normal groups.

Cellular and Molecular Processes in Pulmonary Hypertension

Pulmonary hypertension (PH) is a progressive lung disease characterized by persistent pulmonary vasoconstriction. Another well-recognized characteristic of PH is the muscularization of peripheral pulmonary arteries. This pulmonary vasoremodeling manifests in medial hypertrophy/hyperplasia of smooth muscle cells (SMCs) with possible neointimal formation. The underlying molecular processes for these two major vascular responses remain not fully understood. On the other hand, a series of very recent studies have shown that the increased reactive oxygen species (ROS) seems to be an important player in mediating pulmonary vasoconstriction and vasoremodeling, thereby leading to PH. Mitochondria are a primary site for ROS production in pulmonary artery (PA) SMCs, which subsequently activate NADPH oxidase to induce further ROS generation, i.e., ROS-induced ROS generation. ROS control the activity of multiple ion channels to induce intracellular Ca²⁺ release and extracellular Ca²⁺ influx (ROS-induced Ca²⁺ release and influx) to cause PH. ROS and Ca²⁺ signaling may synergistically trigger an inflammatory cascade to implicate in PH. Accordingly, this paper explores the important roles of ROS, Ca²⁺, and inflammatory signaling in the development of PH, including their reciprocal interactions, key molecules, and possible therapeutic targets.

Targeted therapy with phosphodiesterase 5 inhibitors in patients with pulmonary hypertension due to heart failure and elevated pulmonary vascular resistance: a systematic review

Pulmonary Hypertension due to left heart disease is the most common type of Pulmonary Hypertension. Morbidity and mortality significantly increase once Pulmonary Hypertension is present. Treatment is aimed toward optimizing the underlying condition. Targeted therapy has been evaluated in small studies with mixed results. The goal of this systematic review is to identify the possible benefit and safety of Phosphodiesterase 5 inhibitors in Pulmonary Hypertension due to left heart disease with elevated pulmonary vascular resistance, diagnosed by right heart catheterization. Electronic searches using MEDLINE/PREMEDLINE, EMBASE, and The Cochrane Library were searched on 21 October 2018. Randomized clinical trials comparing Phosphodiesterase 5 inhibitors versus placebo in patients with proven Pulmonary Hypertension by right heart catheterization secondary to left heart disease (both heart failure with reduced ejection fraction and with preserved ejection fraction) and reported pulmonary vascular resistance were included. We identified 436 potentially relevant studies. After reviewing the titles and abstracts to exclude irrelevant articles, five randomized clinical trials were considered for the study. Sildenafil was well tolerated among all studies. Sildenafil was found to improve hemodynamics, exercise capacity, and quality of life in patients with elevated pulmonary vascular resistance. Phosphodiesterase 5 inhibitors therapy in patients with proven Pulmonary Hypertension due to left heart disease and elevated pulmonary vascular resistance by right heart catheterization may improve the quality of life, exercise capacity, and pulmonary hemodynamics. Further prospective randomized controlled studies are needed to confirm.

Machine learning for the diagnosis of pulmonary hypertension

Objective This paper aims to investigate whether machine learning (ML) can be used to predict the state of pulmonary hypertension (PH), including pre-capillary and post-capillary, from echocardiographic data.Methods Two hundred and seventy-five patients with PH who underwent both echocardiography and right heart catheterization were included in the study. Mean pulmonary artery pressure, pulmonary artery wedge pressure measured by right heart catheterization were used as criteria for judging pre-capillary PH and post-capillary PH. Thirteen echocardiographic indicators were used to predict whether the PH was pre-capillary or post-capillary. Nine ML models were used to make predictions. Accuracy was used as the primary reference standard, and the performance of classification model is observed in conjunction with area under curve (AUC), specificity (Sp), sensitivity (Se), Positive Prediction Value (PPV), Negative Prediction Value (NPV), Positive Likelihood Ratio (PLR) and Negative Likelihood Ratio (NLR) and other assessment protocols.Results By comparing the accuracy (ACC), recall rate (Recall) and other model effect evaluation index of the classification under the nine ML models, it can be found that the ML model can effectively identify the pre-capillary PH and the post-capillary PH. LogitBoost performed best in nine ML models (ACC=0.87, Recall=0.83, F1score=0.85, AUC=0.87, Se=0.90, NPV=0.88, PPV=0.87, PLR=8.61 and NLR=0.18, AUC=0.83), it showed good results in identification of the pre-capillary PH (ACC=0.83, Recall=0.87, F-score=0.85); Post-vascular PH (ACC=0.90, Recall=0.88, F-score=0.89). Decision Tree (ACC=0.75, Recall=0.77, F1score=0.78, AUC=0.75, Se=0.72, NPV=0.78, PPV=0.77, PLR=3.66 and NLR=0.29, AUC=0.79) performed worst, and the accuracy of the other seven models was greater than 0.82.Conclusion The classification results of the nine ML models in this paper indicate that the ML method can effectively identify the pre-capillary PH and post-capillary PH from echocardiographic data. Compared with medical diagnosis, ML methods can distinguish between pre-capillary PH and the post-capillary PH under non-invasive conditions.

Pulmonary Hypertension Due to Left Heart Disease

Pulmonary hypertension (PH) due to left heart disease (LHD) is the most common type of PH and is defined as mean pulmonary artery systolic pressure of >20 mm Hg and pulmonary capillary wedge pressure >15 mm Hg during right heart catheterization. LHD may lead to elevated left atrial pressure alone, which in the absence of intrinsic pulmonary vascular disease will result in PH without changes in pulmonary vascular resistance. Persistent elevation in left atrial pressure may, however, also be associated with subsequent pulmonary vascular remodeling, vasoconstriction, and an increase in pulmonary vascular resistance. Hence, there are 2 subgroups of PH due to LHD, isolated postcapillary PH and combined post- and precapillary PH, with these groups have differing clinical implications. Differentiation of pulmonary arterial hypertension and PH due to LHD is critical to guide management planning; however, this may be challenging. Older patients, patients with metabolic syndrome, and patients with imaging and clinical features consistent with left ventricular dysfunction are suggestive of LHD etiology rather than pulmonary arterial hypertension. Hemodynamic measures such as diastolic pressure gradient, transpulmonary gradient, and pulmonary vascular resistance may assist to differentiate pre- from postcapillary PH and offer prognostic insights. However, these are influenced by fluid status and heart failure treatment. Pulmonary arterial hypertension therapies have been trialed in the treatment with concerning results reflecting disease heterogeneity, variation in inclusion criteria, and mixed end point criteria. The aim of this review is to provide an updated definition, discuss possible pathophysiology, clinical aspects, and the available treatment options for PH due to LHD.

Factors Associated With Potentially Inappropriate Phosphodiesterase-5 Inhibitor Use for Pulmonary Hypertension in the United States, 2006 to 2015

BACKGROUND

Use of phosphodiesterase-5 inhibitors (PDE5i) for groups 2 and 3 pulmonary hypertension (PH) is rising nationally, despite guidelines recommending against this low-value practice. Although receiving care across healthcare systems is encouraged to increase veterans' access to specialists critical for PH management, receiving care in 2 systems may increase risk of guideline-discordant prescribing. We sought to identify factors associated with prescribing of PDE5i for group 2/3 PH, particularly, to test the hypothesis that veterans prescribed PDE5i for PH in the community (through Medicare) will have increased risk of subsequently receiving potentially inappropriate treatment in Veterans Health Administration (VA).

METHODS AND RESULTS

We constructed a retrospective cohort of 34 775 Medicare-eligible veterans with group 2/3 PH by linking national patient-level data from VA and Medicare from 2006 to 2015. We calculated adjusted odds ratios (ORs) of receiving daily PDE5i treatment for PH in VA using multivariable models with facility-specific random effects. In this cohort, 1556 veterans received VA prescriptions for PDE5i treatment for group 2/3 PH. Supporting our primary hypothesis, the variable most strongly associated with PDE5i treatment in VA for group 2/3 PH was prior treatment through Medicare (OR, 6.5 [95% CI, 4.9-8.7]). Other variables strongly associated with increased likelihood of VA treatment included more severe disease as indicated by recent right heart failure (OR, 3.3 [95% CI, 2.8-3.9]) or respiratory failure (OR, 3.7 [95% CI, 3.1-4.4]) and prior right heart catheterization (OR, 3.8 [95% CI, 3.4-4.3]).

CONCLUSIONS

Our data suggest a missed opportunity to reassess treatment appropriateness when pulmonary hypertension patients seek prescriptions from VA-a relevant finding given policies promoting shared care across VA and community settings. Interventions are needed to reinforce awareness that pulmonary vasodilators are unlikely to benefit group 2/3 pulmonary hypertension patients and may cause harm.

Pharmacological Treatment of Pulmonary Arterial Hypertension in Australia: Current Trends and Challenges

BACKGROUND

Combination drug therapy for pulmonary arterial hypertension (PAH) is the international standard of care for most patients, however in Australia there are barriers to drug access. This study evaluates current treatment of PAH patients in Australia and the consistency of therapy with international guidelines.

METHODS

Cross-sectional analysis of patients with Group 1 PAH enrolled in the Pulmonary Hypertension Society of Australia and New Zealand Registry (PHSANZ) at 31 December 2017. Drug treatment was classified as monotherapy or combination therapy and adequacy of treatment was determined by risk status assessment using the Registry to Evaluate Early and Long-Term PAH Disease Management (REVEAL) 2.0 risk calculator. Predictors of monotherapy were assessed using a generalised linear model with Poisson distribution and logarithmic link function.

RESULTS

1,046 patients met the criteria for analysis. Treatment was classified as monotherapy in 536 (51%) and combination therapy in 510 (49%) cases. Based on REVEAL 2.0, 184 (34%) patients on monotherapy failed to meet low-risk criteria and should be considered inadequately treated. Independent predictors of monotherapy included age greater than 60 years (risk ratio [RR] 1.23, 95% confidence interval [CI] 1.09-1.38; p=0.001), prevalent enrolment in the registry (RR 1.21 [95%CI 1.08-1.36]; p=0.001) and comorbid systemic hypertension (RR 1.17 [95%CI 1.03-1.32]; p=0.014), while idiopathic/heritable/drug-induced PAH subtype (RR 0.85 [95%CI 0.76-0.96]; p=0.006), functional class IV (RR 0.50 [95%CI 0.29-0.86]; p=0.012), increased right ventricular systolic pressure (RR 0.99 [95%CI 0.99-1.00]; p<0.001) and increased pulmonary vascular resistance (RR 0.96 [95%CI 0.95-0.98]; p<0.001) were less likely to be associated with monotherapy.

CONCLUSIONS

Most Australian PAH patients are treated with monotherapy and a significant proportion remain at risk of poor outcomes. This is below the standard of care recommended by international guidelines and at risk patients should be escalated to combination therapy.

Pulmonary Hypertension

Pulmonary hypertension (PH) is a chronic and progressive disease that presents like many other lung diseases, often leading to a delay in diagnosis, and therefore a delay in optimal therapy. This article provides a review of PH for internists, covering clinical presentation, diagnostic algorithm, different types of PH, and overview of treatments. In addition, it emphasizes the importance of early referral to, and partnership between, PH specialists and physicians on the front lines to improve early diagnosis and optimize management of these complex patients.