Right ventricular remodeling in idiopathic and scleroderma-associated pulmonary arterial hypertension: two distinct phenotypes

Precision Medicine for Pulmonary Vascular Disease: The Future Is Now (2023 Grover Conference Series)

Pulmonary vascular disease is not a single condition; rather it can accompany a variety of pathologies that impact the pulmonary vasculature. Applying precision medicine strategies to better phenotype, diagnose, monitor, and treat pulmonary vascular disease is increasingly possible with the growing accessibility of powerful clinical and research tools. Nevertheless, challenges exist in implementing these tools to optimal effect. The 2023 Grover Conference Series reviewed the research landscape to summarize the current state of the art and provide a better understanding of the application of precision medicine to managing pulmonary vascular disease. In particular, the following aspects were discussed: (1) Clinical phenotypes, (2) genetics, (3) epigenetics, (4) biomarker discovery, (5) application of precision biology to clinical trials, (6) the right ventricle (RV), and (7) integrating precision medicine to clinical care. The present review summarizes the content of these discussions and the prospects for the future.

Single-cell transcriptomics reveal diverging pathobiology and opportunities for precision targeting in scleroderma-associated versus idiopathic pulmonary arterial hypertension

Introduction

Pulmonary arterial hypertension (PAH) involves progressive cellular and molecular change within the pulmonary vasculature, leading to increased vascular resistance. Current therapies targeting nitric oxide (NO), endothelin, and prostacyclin pathways yield variable treatment responses. Patients with systemic sclerosis-associated PAH (SSc-PAH) often experience worse outcomes than those with idiopathic PAH (IPAH).

Methods

Lung tissue samples from four SSc-PAH, four IPAH, and four failed donor specimens were obtained from the Pulmonary Hypertension Breakthrough Initiative (PHBI) lung tissue bank. Single-cell RNA sequencing (scRNAseq) was performed using the 10X Genomics Chromium Flex platform. Data normalization, clustering, and differential expression analysis were conducted using Seurat. Additional analyses included gene set enrichment analysis (GSEA), transcription factor activity analysis, and ligand-receptor signaling. Pharmacotranscriptomic screening was performed using the Connectivity Map.

Results

SSc-PAH samples showed a higher proportion of fibroblasts and dendritic cells/macrophages compared to IPAH and donor samples. GSEA revealed enriched pathways related to epithelial-to-mesenchymal transition (EMT), apoptosis, and vascular remodeling in SSc-PAH samples. There was pronounced differential gene expression across diverse pulmonary vascular cell types and in various epithelial cell types in both IPAH and SSc-PAH, with epithelial to endothelial cell signaling observed. Macrophage to endothelial cell signaling was particularly pronounced in SSc-PAH. Pharmacotranscriptomic screening identified TIE2, GSK-3, and PKC inhibitors, among other compounds, as potential drug candidates for reversing SSc-PAH gene expression signatures.

Discussion

Overlapping and distinct gene expression patterns exist in SSc-PAH versus IPAH, with significant molecular differences suggesting unique pathogenic mechanisms in SSc-PAH. These findings highlight the potential for precision-targeted therapies to improve SSc-PAH patient outcomes. Future studies should validate these targets clinically and explore their therapeutic efficacy.

Application of Metabolomics across the Spectrum of Pulmonary and Critical Care Medicine

In recent years, metabolomics, the systematic study of small-molecule metabolites in biological samples, has yielded fresh insights into the molecular determinants of pulmonary diseases and critical illness. The purpose of this article is to orient the reader to this emerging field by discussing the fundamental tenets underlying metabolomics research, the tools and techniques that serve as foundational methodologies, and the various statistical approaches to analysis of metabolomics datasets. We present several examples of metabolomics applied to pulmonary and critical care medicine to illustrate the potential of this avenue of research to deepen our understanding of pathophysiology. We conclude by reviewing recent advances in the field and future research directions that stand to further the goal of personalizing medicine to improve patient care.

Right Ventricle and Autoimmune Diseases

Autoimmune diseases can express pathologies in specific organs (e.g. thyroid, pancreas, skin) or generate systemic pathologies (generalized lupus erythematosus, rheumatoid arthritis, systemic sclerosis), the latter usually present systemic inflammatory phenomena. Some studies have reported alterations in right ventricular contractility in patients with rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, and juvenile idiopathic arthritis, which may contribute to the known outcome of increased cardiovascular risk. However, there is not much information available on the causes that generate these alterations, the most likely being small vessel damage and fibrosis due to subclinical inflammation.1-5 In this sense, the disease in which the alterations of the right ventricle have been more studied is systemic sclerosis, specifically at the changes induced due to pulmonary arterial hypertension, this being one of the main causes of death in this group of patients after the significant decrease in mortality associated with the sclerodermic renal crisis with the treatment of angiotensin-converting enzyme inhibitors. In this review, we will focus on explaining the structural and functional changes that occur in the right ventricle of patients with systemic sclerosis, from early alterations to late complications. In this context, it is necessary to distinguish between right heart alterations that occur in patients with systemic sclerosis and pulmonary arterial hypertension and those that occur without pulmonary arterial hypertension and that can be attributed to other causes such as microvascular damage or myocardial fibrosis.

Human Resistin Induces Cardiac Dysfunction in Pulmonary Hypertension

Background Cardiac failure is the primary cause of death in most patients with pulmonary arterial hypertension (PH). As pleiotropic cytokines, human resistin (Hresistin) and its rodent homolog, resistin-like molecule α, are mechanistically critical to pulmonary vascular remodeling in PH. However, it is still unclear whether activation of these resistin-like molecules can directly cause PH-associated cardiac dysfunction and remodeling. Methods and Results In this study, we detected Hresistin protein in right ventricular (RV) tissue of patients with PH and elevated resistin-like molecule expression in RV tissues of rodents with RV hypertrophy and failure. In a humanized mouse model, cardiac-specific Hresistin overexpression was sufficient to cause cardiac dysfunction and remodeling. Dilated hearts exhibited reduced force development and decreased intracellular Ca2+ transients. In the RV tissues overexpressing Hresistin, the impaired contractility was associated with the suppression of protein kinase A and AMP-activated protein kinase. Mechanistically, Hresistin activation triggered the inflammation mediated by signaling of the key damage-associated molecular pattern molecule high-mobility group box 1, and subsequently induced pro-proliferative Ki67 in RV tissues of the transgenic mice. Intriguingly, an anti-Hresistin human antibody that we generated protected the myocardium from hypertrophy and failure in the rodent PH models. Conclusions Our data indicate that Hresistin is expressed in heart tissues and plays a role in the development of RV dysfunction and maladaptive remodeling through its immunoregulatory activities. Targeting this signaling to modulate cardiac inflammation may offer a promising strategy to treat PH-associated RV hypertrophy and failure in humans.

Understanding and managing cardiac involvement in systemic sclerosis

INTRODUCTION

Cardiac involvement is common in systemic sclerosis occurring in up to 80% of patients. Primary myocardial dysfunction results from impairment of coronary microvascular circulation, myocardial inflammation and fibrosis with the prevalence of atherosclerosis remaining contradictory.

AREAS COVERED

This review presents the various aspects of cardiac involvement in SSc from a pathophysiological, clinical, diagnostic and therapeutic standpoint. Imaging modalities with emerging role in the understanding of mechanisms and prompt diagnosis of myocardial fibrosis namely cardiac magnetic resonance are also discussed.

EXPERT OPINION

Cardiac involvement in SSc - and particularly primary myocardial disease - remains a challenge as clinical symptoms manifest in advanced stages of heart failure and convey poor prognosis. Over the last years the introduction of sophisticated imaging methods of myocardial function has resulted in a better understanding of the underlying pathophysiological processes of myocardial damage such as microvasculopathy, inflammation, diffuse or focal fibrosis. Such developments could contribute to the identification of patients at higher risk for subclinical heart involvement for whom diligent surveillance and prompt initiation of therapy with cardioprotective and/or immunosuppressive drugs coupled with invasive interventions namely radiofrequency ablation, implantable cardioverter-defibrillator when indicated, may improve long-term outcomes.

Metabolomic Profiles Differentiate Scleroderma-PAH From Idiopathic PAH and Correspond With Worsened Functional Capacity

BACKGROUND

The prognosis and therapeutic responses are worse for pulmonary arterial hypertension associated with systemic sclerosis (SSc-PAH) compared with idiopathic pulmonary arterial hypertension (IPAH). This discrepancy could be driven by divergence in underlying metabolic determinants of disease.

RESEARCH QUESTION

Are circulating bioactive metabolites differentially altered in SSc-PAH vs IPAH, and can this alteration explain clinical disparity between these PAH subgroups?

STUDY DESIGN AND METHODS

Plasma biosamples from 400 patients with SSc-PAH and 1,082 patients with IPAH were included in the study. Another cohort of 100 patients with scleroderma with no PH and 44 patients with scleroderma with PH was included for external validation. More than 700 bioactive lipid metabolites, representing a range of vasoactive and immune-inflammatory pathways, were assayed in plasma samples from independent discovery and validation cohorts using liquid chromatography/high-resolution mass spectrometry-based approaches. Regression analyses were used to identify metabolites that exhibited differential levels between SSc-PAH and IPAH and associated with disease severity.

RESULTS

From hundreds of circulating bioactive lipid molecules, five metabolites were found to distinguish between SSc-PAH and IPAH, as well as associate with markers of disease severity. Relative to IPAH, patients with SSc-PAH carried increased levels of fatty acid metabolites, including lignoceric acid and nervonic acid, as well as eicosanoids/oxylipins and sex hormone metabolites.

INTERPRETATION

Patients with SSc-PAH are characterized by an unfavorable bioactive metabolic profile that may explain the poor and limited response to therapy. These data provide important metabolic insights into the molecular heterogeneity underlying differences between subgroups of PAH.

Right cardiac involvement in lung diseases: a multimodality approach from diagnosis to prognostication

Lung diseases are amongst the main healthcare issues in the general population, having a high burden of morbidity and mortality. The cardiovascular system has a key role in patients affected by respiratory disorders. More specifically, the right ventricle (RV) enables the impaired lung function to be overcome in an initial stage of disease process, reducing the severity of dyspnoea. In addition, two of the main causes of death in this setting are RV failure and sudden cardiac death (SCD). Echocardiography is regarded as a useful and easily available tool in assessing RV function. Several noninvasive echocardiographic parameters of elevated pulmonary pressures and RV function have been proposed. The combination of different parameters and imaging methods is paramount and researches regarding RV impairment using these indices has been specifically addressed in relation to the chronic obstructive and restrictive lung disease in order to guide the clinicians in the management of these patients. Cardiac involvement in lung diseases is often observed, and RV changes are reported also in early stages of pulmonary diseases. The role of right ventricle in chronic respiratory disease patients has to be evaluated in detail to describe the response to therapy and the degree of disease progression through multimodality and advanced imaging techniques. The aim of this review is to describe the different pathophysiological mechanisms of cardiac impairment in primary lung disease (such as chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF) and sarcoidosis) and to summarize the role of cardiac multimodality imaging in the diagnosis and the prognosis of these diseases.

Diagnostic and prognostic markers and treatment of connective tissue disease-associated pulmonary arterial hypertension: current recommendations and recent advances

INTRODUCTION

Pulmonary arterial hypertension (PAH), also referred to as group 1 pulmonary hypertension, occurs either primarily or in association with other diseases such as connective tissue diseases (CTD). Of CTD, systemic sclerosis (SSc), systemic lupus erythematosus and mixed connective tissue disease are commonly accompanied with PAH. It is of note that SSc-PAH is associated with distinctive histopathology, an unfavorable outcome, and a blunted responsiveness to modern PAH therapies.

AREAS COVERED

The data in articles published until May 2020 in peer-reviewed journals, covered by PubMed databank, are discussed. The current review introduces recent advances over the past years which have moved our understanding of CTD-PAH forward and discusses what we are currently able to do and what will be necessary in the future to overcome the yet unsatisfactory situation in the management of CTD-PAH, particularly in that of SSc-PAH.

EXPERT OPINION

A multifaceted and integrated approach would be crucial to improve the outcome of patients with SSc-PAH. The authors also propose a possible algorithm to classify and treat SSc patients with suspicion of pulmonary vascular disease.

Pulmonary Hypertension Phenotypes in Systemic Sclerosis: The Right Diagnosis for the Right Treatment

Systemic sclerosis is an auto-immune disease characterized by skin involvement that often affects multiple organ systems. Pulmonary hypertension is a common finding that can significantly impact prognosis. Molecular pathophysiological mechanisms underlying pulmonary hypertension in systemic sclerosis can be extremely heterogeneous, leading to distinct clinical phenotypes. In addition, different causes of pulmonary hypertension may overlap within the same patient. Since pulmonary hypertension treatment is very different for each phenotype, it is fundamental to perform an adequate diagnostic work-up to properly and promptly identify the prevalent mechanism underlying pulmonary hypertension in order to start the right therapies. When pulmonary hypertension is caused by a primary vasculopathy of the small pulmonary arteries, treatment with pulmonary vasodilators, often in an initial double-combination regimen, is indicated, aimed at reducing the mortality risk profile. In this review, we describe the different clinical phenotypes of pulmonary hypertension in the scleroderma population and discuss the utility of clinical tools to identify the presence of pulmonary vascular disease. Furthermore, we focus on systemic sclerosis-associated pulmonary arterial hypertension, highlighting the advances in the knowledge of right ventricular dysfunction in this setting and the latest updates in terms of treatment with pulmonary vasodilator drugs.

Cardiac magnetic resonance imaging as a prognostic biomarker in treatment-naïve pulmonary hypertension

PURPOSE

Targeted treatment for pulmonary arterial hypertension (PAH), diagnosed via right heart catheterization (RHC), has been shown to improve morbidity and mortality. Identifying characteristics that predict clinical worsening has been challenging. We sought to evaluate the role of cardiac Magnetic Resonance Imaging (CMR) as a predictor of clinical worsening in a cohort of treatment-naïve pulmonary hypertension (PH) patients.

METHODS

We performed a retrospective single center analysis of all adults with newly diagnosed treatment-naïve PH between January 1st 2013 and January 1st 2019. Patients with World Health Organization (WHO)-Group I PAH or WHO-Group II/III PH disease, who underwent both CMR (Signa Horizon 1.5 T, General Electric, Milwaukee, WI and Siemens Espree 1.5 T, Munich, Germany) and RHC testing prior to targeted PAH treatment, were included for analysis. Cox proportional hazards models were constructed.

RESULTS

A total of 38 patients, of which 12 (32 %) experienced the primary outcome of clinical worsening. were included in the final analysis, Patients with clinical worsening were significantly more likely to have RV dysfunction by CMR (including lower RV ejection fraction (HR 0.93, p = 0.007) and more RV dilation (HR 1.02, p = 0.005-0.021)) and RHC (including worse pulmonary vascular resistance (HR 1.32, p < 0.001)), even after adjustment for disease severity. Both CMR and RHC measures of RV dysfunction were found to be equally effective in predicting clinical worsening, regardless of PH etiology.

CONCLUSIONS

In treatment-naïve PH patients, including those with WHO-Group II/III disease, both CMR and RHC measures independently and significantly predicted clinical worsening, even after adjustment for disease severity.

Progress in Understanding, Diagnosing, and Managing Cardiac Complications of Systemic Sclerosis

PURPOSE OF THE REVIEW

Systemic sclerosis (scleroderma) is a complex autoimmune disease that commonly involves the cardiovascular system. Even if often subclinical, cardiac involvement is considered a poor prognostic factor as it is a leading cause of death in scleroderma patients. We review the cardiac manifestations of scleroderma, the diagnostic methods useful in detection, and current advances in therapeutic management.

RECENT FINDINGS

Beside the routine exams for the assessment of cardiac status (including EKG, standard echocardiography, provocative tests) novel techniques such as myocardial strain imaging on echocardiography, cardiac magnetic resonance imaging, invasive hemodynamic assessment, and endomyocardial biopsy have been demonstrated to be useful in understanding the cardiac alterations that typically affect scleroderma patients. Recent application of novel cardiac detection strategies is providing increased insight into the breadth and pathogenesis of cardiac complications of scleroderma. Further studies coupling exercise provocation, invasive and imaging assessment, and mechanistic studies in scleroderma cardiac tissue are needed to develop the optimal approach to early detection of cardiac disease in scleroderma and targeted therapies.

The importance of right ventricular function in patients with pulmonary arterial hypertension

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a progressive, life-threatening, and incurable disease. Its prognosis is based on right ventricular (RV) function. Therefore, adequate assessment of RV function is mandatory. Areas covered: This article presents the case of a patient with PAH in which the traditional diagnostic approach did not provide a complete assessment of RV function. The authors show how the analysis of other parameters yielded additional information that improved the management of this patient. Expert commentary: Despite current treatments, PAH often worsens due to progressive RV dysfunction. Appropriate assessment of RV function may facilitate the early identification of patients at risk of RV function impairment. More aggressive treatment of PAH might delay progression of the disease. Traditional risk stratification, which is based on New York Heart Association/World Health Organization (NYHA/WHO) functional class evaluation, the 6-minute walk test, and right heart catheterization, proves insufficient in many PAH patients, as it does not provide complete information about RV function. Thus, further parameters are required. Analysis of RV function, in addition to echocardiography and cardiopulmonary exercise testing, may add relevant prognostic information and improve therapy.

Non-invasive right ventricular load adaptability indices in patients with scleroderma-associated pulmonary arterial hypertension

Scleroderma-associated pulmonary arterial hypertension (SSc-PAH) is associated with worse outcome than idiopathic pulmonary arterial hypertension (IPAH), potentially due to worse right ventricular adaptation to load as suggested by pressure–volume loop analysis. The value of non-invasive load-adaptability metrics has not been fully explored in SSc-PAH. This study sought to assess whether patients with incident SSc-PAH have worse echocardiographic load-adaptability metrics than patients with IPAH. Twenty-two patients with incident SSc-PAH were matched 1:1 with IPAH based on pulmonary vascular resistance. Echocardiographic load-adaptability indices were divided into: surrogates of ventriculo-arterial coupling (e.g. right ventricular area change/end-systolic area), indices reflecting the proportionality of load adaptation (e.g. tricuspid regurgitation velocity-time integral normalized for average right ventricular radius), and simple ratios (e.g. tricuspid annular plane systolic excursion/right ventricular systolic pressure). The prognostic value of these indices for clinical worsening (i.e. death, transplant, or hospitalization for heart failure) at one year was explored. The two groups were comprised of patients of similar age, with similar cardiac index, pulmonary resistance, capacitance and NT-proBNP levels (p > 0.10). There was no difference in baseline right ventricular dimension, function or load-adaptability indices. At one year, eight (36.4%) SSc-PAH patients had experienced clinical worsening (eight hospitalizations and two deaths) versus one hospitalization in the IPAH group. Load adaptation at one year in survivors was not worse in SSc-PAH (p > 0.33). Patients with IPAH responded better to therapy than SSc-PAH in terms of reduction of right ventricular areas at one year (p < 0.05). Right ventricular load-adaptability echocardiographic indices do not appear to capture the increased risk of negative outcomes at one year associated with SSc-PAH.

Right Ventricle Remodeling and Function in Scleroderma Patients

Scleroderma, known also as systemic sclerosis (SSc), is a severe disease associated with high mortality rates, and right ventricular (RV) remodeling and dysfunction, along with pulmonary artery hypertension (PAH), are among the most important internal organ manifestations of this disease. PAH has a higher prevalence in patients with SSc compared to the general population and represents a significant predictor of mortality in SSc. In patients with SSc, the morphological remodeling and alteration of RV function begin even before the setting of PAH and lead to development of a specific adaptive pattern of the RV which is different from the one recorded in patients with IAPH. These alterations cause worse outcomes and increased mortality rates in SSc patients. Early detection of RV dysfunction and remodeling is possible using modern imaging tools currently available and can indicate the initiation of specific therapeutic measures before installation of PAH. The aim of this review is to summarize the current knowledge related to mechanisms involved in the remodeling and functional alteration of the RV in SSc patients.

Differences in Right Ventricular Functional Changes during Treatment between Systemic Sclerosis-associated Pulmonary Arterial Hypertension and Idiopathic Pulmonary Arterial Hypertension

RATIONALE

Patients with systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) continue to have an unacceptably high mortality rate despite the progress achieved with pulmonary arterial vasodilator therapies.

OBJECTIVES

We sought to determine whether SSc-PAH is a clinically distinct pulmonary vascular disease phenotype when compared with idiopathic pulmonary arterial hypertension (IPAH) on the basis of progression of echocardiographic right ventricular (RV) dysfunction.

METHODS

Retrospective analysis of echocardiographic data in 13 patients with SSc-PAH and 11 patients with IPAH was used to delineate the progression of RV dysfunction during single or combination pulmonary arterial vasodilator therapy. All patients had right heart catheterization-confirmed pulmonary arterial hypertension as well as complete baseline (at the time of diagnosis) and follow-up (most recent) echocardiograms. We excluded patients with significant scleroderma-associated interstitial lung disease. Adjusting for time of follow-up and disease duration, we performed mixed model regression analyses comparing the changes between the two groups for different echocardiographic variables: tricuspid annular plane systolic excursion, tricuspid regurgitation jet velocity, right atrial area, and RV diameter.

RESULTS

The mean ages for the SSc-PAH and IPAH groups were 60.8 and 48.2 years, respectively. The mean follow-up periods for the two groups were 3.8 and 1.95 years, respectively. Tricuspid annular plane systolic excursion did not improve in patients with SSc-PAH, whereas it increased in the patients with IPAH (-0.38 mm, P = 0.87; vs. +5.6 mm, P = 0.02). The other echocardiographic variables showed a trend toward worsening in the SSc-PAH group and improvement in the IPAH group.

CONCLUSIONS

Our results indicate that, in patients with SSc-PAH, echocardiographic RV function does not improve over time compared with that of patients with IPAH, despite institution of pulmonary artery vasodilator therapies.

Pulmonary arterial hypertension associated with connective tissue diseases: A review focusing on distinctive clinical aspects

Recent studies have clarified that pulmonary arterial hypertension associated with connective tissue diseases (CTD-PAH) has some distinctive clinical aspects from other PAH, such as high prevalence, venous and cardiac involvement, less favourable outcome, helpfulness of detection algorithm, response to immunosuppression, pre-PAH conditions in borderline pulmonary arterial pressure and coexistence of interstitial lung disease. In this review, by focusing on these distinctive aspects, we discuss how to provide an efficacious and safe management of CTD-PAH and garner attention to areas where further evidence is desired.

Differences in right ventricular morphology, not function, indicate the nature of increased afterload in pulmonary hypertensive subjects with normal left ventricular function

BACKGROUND

The aim of study was to assess whether a specific morphology of the right ventricle (RV) by 2D echo predicts the hemodynamic nature of pulmonary hypertension (PH).

METHODS

We reviewed clinical, 2D echo, and hemodynamic data of 100 patients with PH: divided into three groups: PH from pulmonary vascular disease (PH_PVD ; n = 34) with pulmonary vascular resistance (PVR) > 3 mm Hg/L/min (Wood unit [WU]) and pulmonary artery wedge pressure (PAWP) ≤ 15 mm Hg, pulmonary venous hypertension (PVH; n = 33) with PVR < 3 WU and PAWP > 15 mm Hg and PH_MIXED (n = 33) with PVR > 3 WU and PAWP > 15 mm Hg. We analyzed several two-dimensional parameters of right heart morphology and function, including the degree of tapering of the RV diameter from base (just above tricuspid annulus) to apex (level of moderator band) in the apical four-chamber view. P = <.05.

RESULTS

Baseline characteristics were similar in all three groups: age 62 ± 14.4 years, 69% females, 57% Caucasians. Hemodynamics and 2D echo data of PH_PVD vs PVH vs PH_MIXED were as follows: PVR 13 ± 6 vs 2 ± 1 vs 7 ± 2 WU, mean pulmonary artery pressure 53 ± 14 vs 34 ± 8 vs 49 ± 8 mm Hg and cardiac index 2.0 ± 0.5 vs 2.8 ± 0.7 vs 2.2 ± 0.7 L/m² , RV base/apex ratio during systole (sRV_b/a ) 1.3 ± 0.2 vs 2.6 ± 0.5 vs 1.5 ± 0.3. Thus, sRV_b/a was twofold higher in the PVH vs PH_PVD cohort. On ROC analysis, the AUC for sRV_b/a for predicting PVR > 3 WU was 0.873, with optimal cutoff of 1.5.

CONCLUSION

Systolic RV base/apex ratio is a simple 2D index of RV shape that powerfully predicts a PVR > 3 WU and provides powerful discriminating ability between PVH and PH_PVD .

Idiopathic and Systemic Sclerosis-Associated Pulmonary Arterial Hypertension: A Comparison of Demographic, Hemodynamic, and MRI Characteristics and Outcomes

BACKGROUND

Previous studies have identified survival in systemic sclerosis (SSc)-associated pulmonary arterial hypertension (SSc-PAH) as being worse than in idiopathic pulmonary arterial hypertension (IPAH). We investigated differences between these conditions by comparing demographic, hemodynamic, and radiological characteristics and outcomes in a large cohort of incident patients.

METHODS

Six hundred fifty-one patients diagnosed with IPAH or SSc-associated precapillary pulmonary hypertension were included. Patients with pulmonary disease or two or more risk factors for left heart disease were identified, leaving a primary analysis set of 375 subjects. Subgroup analysis using cardiac magnetic resonance (CMR) imaging was performed.

RESULTS

Median survival was 7.8 years in IPAH and 3 years in SSc-PAH (P < .001). Patients with SSc-PAH were older with less severe hemodynamics but lower gas transfer (diffusing capacity for carbon monoxide [Dlco]). Independent prognostic factors were age, SSc, Dlco, pulmonary artery saturation, and stroke volume. After excluding patients with normal or only mildly elevated resistance, there was no difference in the relationship between pulmonary vascular resistance (PVR) and compliance in IPAH and SSc-PAH. The relationship between mean pulmonary arterial pressure (mPAP) and systolic pulmonary arterial pressure (sPAP) in IPAH was identical to that previously reported (mPAP = 0.61 sPAP + 2 mm Hg). The relationship in SSc-PAH was similar: mPAP = 0.58 sPAP + 2 mm Hg (P value for difference with IPAH = 0.095). The correlation between ventricular mass index assessed at CMR imaging and PVR was stronger in SSc-PAH.

CONCLUSIONS

The reasons for poorer outcomes in SSc-PAH are likely to be multifactorial, including but not limited to older age and reduced gas transfer.

Right Ventricular Functional Reserve in Pulmonary Arterial Hypertension

BACKGROUND

Right ventricular (RV) functional reserve affects functional capacity and prognosis in patients with pulmonary arterial hypertension (PAH). PAH associated with systemic sclerosis (SSc-PAH) has a substantially worse prognosis than idiopathic PAH (IPAH), even though many measures of resting RV function and pulmonary vascular load are similar. We therefore tested the hypothesis that RV functional reserve is depressed in SSc-PAH patients.

METHODS AND RESULTS

RV pressure-volume relations were prospectively measured in IPAH (n=9) and SSc-PAH (n=15) patients at rest and during incremental atrial pacing or supine bicycle ergometry. Systolic and lusitropic function increased at faster heart rates in IPAH patients, but were markedly blunted in SSc-PAH. The recirculation fraction, which indexes intracellular calcium recycling, was also depressed in SSc-PAH (0.32±0.05 versus 0.50±0.05; P=0.039). At matched exercise (25 W), SSc-PAH patients did not augment contractility (end-systolic elastance) whereas IPAH did (P<0.001). RV afterload assessed by effective arterial elastance rose similarly in both groups; thus, ventricular-vascular coupling declined in SSc-PAH. Both end-systolic and end-diastolic RV volumes increased in SSc-PAH patients to offset contractile deficits, whereas chamber dilation was absent in IPAH (+37±10% versus +1±8%, P=0.004, and +19±4% versus -1±6%, P<0.001, respectively). Exercise-associated RV dilation also strongly correlated with resting ventricular-vascular coupling in a larger cohort.

CONCLUSIONS

RV contractile reserve is depressed in SSc-PAH versus IPAH subjects, associated with reduced calcium recycling. During exercise, this results in ventricular-pulmonary vascular uncoupling and acute RV dilation. RV dilation during exercise can predict adverse ventricular-vascular coupling in PAH patients.