Survival in patients with idiopathic, familial, and anorexigen-associated pulmonary arterial hypertension in the modern management era

Pulmonary arterial hypertension: insights from genetic studies

Familial pulmonary arterial hypertension (FPAH) was described 60 years ago, but real progress in understanding its origins and pathogenesis is just beginning. Germline mutations in bone morphogenetic protein receptor type 2 (BMPR2) are responsible for the disease in most families, and also in many sporadic cases of idiopathic PAH. Heritable PAH refers to patients with a positive family history, or with a responsible genetic mutation, and is an autosomal dominant disease that affects females disproportionately, may occur at any age, and is characterized by reduced penetrance and variable expressivity. These characteristics suggest that other endogenous or exogenous factors modify its expression. Several different factors have recently been demonstrated to modify the clinical expression of BMPR2 mutation, including estrogen metabolites and functional polymorphisms in transforming growth factor-β1 and CYP1B1. Furthermore, a linkage study recently identified modifier loci for BMPR2 clinical expression, which suggests an oligogenic model. Clinical testing for BMPR2 mutations is available for families with heritable and idiopathic PAH, and is an evolving model of personalized medicine. Variable age of onset and decreased penetrance confound genetic counseling, because the majority of carriers of a BMPR2 mutation will never develop PAH, but often transmit the risk to their progeny.

Validation of the pulmonary hypertension connection equation for survival prediction in pulmonary arterial hypertension

OBJECTIVE

The pulmonary hypertension connection (PHC) equation predicts contemporary survival in idiopathic, heritable, and anorexigen-associated pulmonary arterial hypertension (PAH). The aim of this study is to validate the PHC equation in a prospective PAH population cohort and compare its predictability with the French equation.

METHODS

We compared the rates of actual survival in patients prospectively followed for up to 3.5 years in four double-blind, randomized trials and their open-label extension studies with predicted survival calculated using the PHC equation [(P(t) = e((-A(x,y,z)t)), A(x,y,z) = e((-1.270-0.0148x + 0.0402y - 0.361z)), where P(t) is the probability of survival, t the time interval in years, x the mean pulmonary artery pressure, y the mean right atrial pressure, and z the cardiac index] and the French equation in patients with idiopathic, heritable, and anorexigen-associated PAH (n = 449).

RESULTS

Mean age was 44 ± 15 years, 77% were women, and 80% had World Health Organization (WHO) functional class III/IV symptoms. The mean 6-min walk distance (6MWD) was 354 ± 95 m. The baseline hemodynamics were as follows: mean right atrial pressure 10 ± 6 mm Hg, mean pulmonary artery pressure 59 ± 15 mm Hg, and cardiac output 4.1 ± 1.5 L/min. The 1-, 2-, and 3-year Kaplan-Meier survival rates were 89%, 80%, and 70%, respectively; the nonadjusted survival rates were 91%, 87%, and 84%, respectively. The expected survival predicted by both the PHC and the French equations was similar to the actual observed Kaplan-Meier survival and was within its 95% confidence limits. The PHC equation also performed well when used in patients with WHO functional class III/IV, cardiac output < 4 L/min, or 6MWD < 380 m.

CONCLUSION

Risk prediction equations (PHC and French) accurately predicted survival and may be useful for risk estimation in patients with idiopathic, heritable, and anorexigen-associated PAH in large cohort studies. Their use for survival prediction for individual patients needs further study.

Prevalence and impact of coronary artery disease in patients with pulmonary arterial hypertension

The occurrence and impact of coronary artery disease (CAD) among patients with pulmonary arterial hypertension (PAH) are unknown. We aimed to determine the prevalence, clinical correlates, and effect of CAD in patients with PAH. We reviewed the medical records of consecutive patients diagnosed with PAH at a university-based referral center for pulmonary vascular disease from January 1990 to May 2010. The patients systematically underwent right heart catheterization and coronary angiography as a part of their evaluation. The patients with PAH with CAD (defined as ≥50% stenosis in ≥1 major epicardial coronary artery) were compared to patients without CAD. Among the 162 patients with PAH, the prevalence of CAD was 28.4%. The presence of CAD was associated with older age (66.6 ± 11.5 vs 49.2 ± 14.0 years, p <0.001), systemic hypertension, and dyslipidemia. The patients with PAH and CAD had a lower mean pulmonary arterial pressure (44.6 ± 11.1 vs 49.2 ± 14.0 mm Hg; p = 0.02) than patients without CAD. During a median follow-up of 36 months, 73 patients died. The presence of CAD was a predictor of all-cause mortality on univariate analysis (hazard ratio 1.97, 95% confidence interval 1.21 to 3.20) but not on multivariate analysis, which identified older age (hazard ratio 1.03, 95% confidence interval 1.01 to 1.05) and right atrial pressure (hazard ratio 1.08, 95% confidence interval 1.03 to 1.14) as the only independent predictors. In conclusion, our study has demonstrated that CAD is common among patients with PAH. CAD prevalence increases with age, dyslipidemia, and hypertension, but we did not detect an independent prognostic effect of CAD on mortality.

Treatment of pulmonary arterial hypertension with targeted therapies

Pulmonary arterial hypertension (PAH) is a rare disorder characterized by progressive obliteration of the pulmonary microvasculature that results in elevated pulmonary vascular resistance and premature death. Although no cure exists for PAH, improved understanding of the pathobiological mechanisms of this disease has resulted in the development of effective therapies that target specific aberrant pathways. Agents that modulate abnormalities in the prostacyclin, endothelin, and nitric oxide pathways have been shown in randomized, controlled studies to confer improvements in functional status, pulmonary hemodynamics, and possibly even slow disease progression. Several additional pathways believed to play an important role in the pathogenesis of PAH have been identified as potentially useful therapeutic targets and a number of investigative approaches focusing on these targets are in active development. In this Review, we highlight the pharmacological agents currently available for the treatment of PAH and discuss potential novel strategies.

Cardiac magnetic resonance imaging-derived pulmonary artery distensibility index correlates with pulmonary artery stiffness and predicts functional capacity in patients with pulmonary arterial hypertension

BACKGROUND

Increased stiffness of the pulmonary vascular bed is known to increase mortality in patients with pulmonary arterial hypertension (PAH); and pulmonary artery (PA) stiffness is also thought to be associated with exercise capacity. The purpose of the present study was to investigate whether cardiac magnetic resonance imaging (CMRI)-derived PA distensibility index correlates with PA stiffness estimated on right heart catheterization (RHC) and predicts functional capacity (FC) in patients with PAH.

METHODS AND RESULTS

Thirty-five consecutive PAH patients (23% male, mean age, 44 ± 13 years; 69% idiopathic) underwent CMRI, RHC, and 6-min walk test (6MWT). PA distensibility indices were derived from cross-sectional area change (%) in the transverse view, perpendicular to the axis of the main PA, on CMRI [(maximum area-minimum area)/minimum area during cardiac cycle]. Among the PA stiffness indices, pulmonary vascular resistance (PVR) and PA capacitance were calculated using hemodynamic dataset from RHC. CMRI-derived PA distensibility was inversely correlated with PVR (R²=0.34, P<0.001) and directly correlated with PA capacitance (R²=0.35, P<0.001), and the distance in the 6MWT (R²=0.61, P<0.001). Furthermore, PA distensibility <20% predicted poor FC (<400m in 6MWT) with a sensitivity of 82% and a specificity of 94%.

CONCLUSIONS

Non-invasive CMRI-derived PA distensibility index correlates with PA stiffness and can predict FC in patients with PAH.

Sex differences in the diagnosis, treatment, and outcome of patients with pulmonary arterial hypertension enrolled in the registry to evaluate early and long-term pulmonary arterial hypertension disease management

BACKGROUND

Pulmonary arterial hypertension (PAH) is a life-threatening disease that affects more women than men. The reasons for the female preponderance are unclear, and there are limited data available for men with PAH.

METHODS

Data from the Registry to Evaluate Early and Long-term PAH Disease Management (REVEAL Registry) were analyzed to explore sex differences among patients with PAH with regard to 2-year survival from enrollment and 5-year survival from time of diagnosis.

RESULTS

The data set included 2,318 women and 651 men. More women had PAH associated with connective tissue disease (P < .001), and more men had portopulmonary hypertension (P < .001) and HIV-associated PAH (P < .001). More women had congenital heart disease-associated PAH (P = .017), thyroid disease (P < .001), and depression reported (P ≤ .001). At diagnosis, men had higher mean pulmonary artery pressure (53 ± 14 vs 51 ± 14.3 mm Hg; P = .013) and mean right atrial pressure (10 ± 6 vs 9 ± 6 mm Hg; P = .031). Women had better survival estimates for 2 years from enrollment and for 5 years from diagnosis. Stratifying by age showed that survival from enrollment was similar between men and women aged < 60 years at enrollment, whereas men aged ≥ 60 years have lower survival rates compared with women aged ≥ 60 years.

CONCLUSIONS

Our findings highlight similarities and differences between men and women with PAH, raising questions for future exploration regarding the role of hormones and sex in causation and survival in PAH.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00370214; URL: www.clinicaltrials.gov.

Compelling evidence of long-term outcomes in pulmonary arterial hypertension? A clinical perspective

Pulmonary arterial hypertension (PAH) is a rare and progressive disease of the pulmonary arterial circulation that is characterized by a progressive rise in pulmonary vascular resistance, eventually leading to right-heart failure and death. There are currently 3 classes of drugs approved for the treatment of PAH: prostacyclin analogues, endothelin receptor antagonists, and phosphodiesterase type 5 inhibitors. All of these therapies have been approved for use on the basis of relatively small, short-term studies, yet it is common for each to be administered (alone or in combination) over the lifetime of a patient with PAH. Very few prospective, well-controlled PAH studies have examined long-term clinical outcomes associated with current medical therapy. Therefore, data that support the long-term therapeutic benefits of these long-term PAH therapies are limited and derived primarily from uncontrolled, observational studies. In this perspective, the authors review the published research to assess the strengths and weaknesses of the data that support the long-term clinical benefit of current PAH therapies. The authors conclude that current medical therapies approved for the treatment of PAH can provide sustained benefits in hemodynamic function and exercise capacity. The cumulative evidence, in the form of meta-analysis and registry data, suggest that patients are living longer compared with untreated patients; the reasons are likely multifactorial. Although definitive evidence will require randomized and properly controlled long-term trials, the current evidence supports the long-term use of these drugs for the treatment of patients with PAH.

Apelin and pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a devastating disease characterized by pulmonary vasoconstriction, pulmonary arterial remodeling, abnormal angiogenesis and impaired right ventricular function. Despite progress in pharmacological therapy, there is still no cure for PAH. The peptide apelin and the G-protein coupled apelin receptor (APLNR) are expressed in several tissues throughout the organism. Apelin is localized in vascular endothelial cells while the APLNR is localized in both endothelial and smooth muscle cells in vessels and in the heart. Apelin is regulated by hypoxia inducible factor -1α and bone morphogenetic protein receptor-2. Patients with PAH have lower levels of plasma-apelin, and decreased apelin expression in pulmonary endothelial cells. Apelin has therefore been proposed as a potential biomarker for PAH. Furthermore, apelin plays a role in angiogenesis and regulates endothelial and smooth muscle cell apoptosis and proliferation complementary and opposite to vascular endothelial growth factor. In the systemic circulation, apelin modulates endothelial nitric oxide synthase (eNOS) expression, induces eNOS-dependent vasodilatation, counteracts angiotensin-II mediated vasoconstriction, and has positive inotropic and cardioprotective effects. Apelin attenuates vasoconstriction in isolated rat pulmonary arteries, and chronic treatment with apelin attenuates the development of pulmonary hypertension in animal models. The existing literature thus renders APLNR an interesting potential new therapeutic target for PH.

Inhibition of MRP4 prevents and reverses pulmonary hypertension in mice

Multidrug resistance-associated protein 4 (MRP4, also known as Abcc4) regulates intracellular levels of cAMP and cGMP in arterial SMCs. Here, we report our studies of the role of MRP4 in the development and progression of pulmonary arterial hypertension (PAH), a severe vascular disease characterized by chronically elevated pulmonary artery pressure and accompanied by remodeling of the small pulmonary arteries as a prelude to right heart failure and premature death. MRP4 expression was increased in pulmonary arteries from patients with idiopathic PAH as well as in WT mice exposed to hypoxic conditions. Consistent with a pathogenic role for MRP4 in PAH, WT mice exposed to hypoxia for 3 weeks showed reversal of hypoxic pulmonary hypertension (PH) following oral administration of the MRP4 inhibitor MK571, and Mrp4-/- mice were protected from hypoxic PH. Inhibition of MRP4 in vitro was accompanied by increased intracellular cAMP and cGMP levels and PKA and PKG activities, implicating cyclic nucleotide-related signaling pathways in the mechanism underlying the protective effects of MRP4 inhibition. Our data suggest that MRP4 could represent a potential target for therapeutic intervention in PAH.

Bad blood, bad endothelium: ill fate?

In this issue of Blood, Farha and colleagues have identified a myeloproliferative process that is intrinsic to human pulmonary arterial hypertension (PAH), but appears coupled to pathologic vascular remodeling in the lung.

Does the outcome justify an oral-first treatment strategy for management of pulmonary arterial hypertension?

BACKGROUND

Guidelines for the treatment of World Health Organization (WHO) functional class (FC) III pulmonary arterial hypertension (PAH) provide for oral (PO) therapy or parenteral prostacyclins at the discretion of expert physicians. The objective of this study was to assess the appropriateness of PO-first treatment in patients with WHO FC III PAH.

METHODS

This study was a retrospective analysis of 79 treatment-naive adult patients with idiopathic, familial, or anorexigen-associated PAH, referred to a single pulmonary hypertension center. Forty-eight received either PO therapy with an endothelin receptor antagonist, calcium channel blocker, or phosphodiesterase inhibitor (PO group) and 31 an IV or subcutaneous (SC) prostacyclin (IV/SC group).

RESULTS

Patients in the IV/SC group had a significantly worse baseline hemodynamic profile; however, on univariate analysis, there was no association between hemodynamics and mortality. Initial treatment with PO vs IV/SC therapy was associated with a lower overall mortality (20.8% vs 45.2%, P = .02) and a lower 5-year mortality (14.6% vs 32.3%, P = .062). Based on the National Institutes of Health equation, actual survival for patients who received PO therapy was greater than predicted at 5 years. Finally, there were similar improvements between groups in 6-min walk distance (P = .38) at 6 to 12 months after initiation of treatment.

CONCLUSIONS

For WHO FC III PAH that is idiopathic, familial, or anorexigen associated, the clinical decision for treatment with a PO-first strategy is associated with a high survival rate when patients are appropriately risk stratified prior to initiation of therapy. The more potent prostacyclins can be reserved for high-risk patients, those with evidence of disease progression, or those with treatment failure.

Prolonged overcirculation-induced pulmonary arterial hypertension as a cause of right ventricular failure

AIMS

Three-month chronic systemic-to-pulmonary shunting in growing piglets has been reported as an early pulmonary arterial hypertension (PAH) model with preserved right ventricular (RV) function. We sought to determine whether prolonged shunting might be associated with more severe PAH and RV failure.

METHODS AND RESULTS

Fourteen growing piglets were randomized to a sham operation or the anastomosis of the left innominate artery to the pulmonary arterial trunk. Six months later, the shunt was closed and the animals underwent haemodynamic evaluation followed by tissue sampling for pathobiological assessment. Prolonged shunting had resulted in increased mean pulmonary artery pressure (22 ± 2 versus 17 ± 1 mmHg) and pulmonary arteriolar medial thickness, while cardiac output was decreased. However, RV-arterial coupling was markedly deteriorated, with a ~50% decrease in the ratio of end-systolic to pulmonary arterial elastances (Ees/Ea). Lung tissue expressions of endothelin-1, angiopoietin-1, and bone morphogenetic protein receptor-2 were similarly altered compared with previously observed after 3-month shunting. At the RV tissue level, pro-apoptotic ratio of Bax-to-Bcl-2 expressions and caspase-3 activation were increased, along with an increase in cardiomyocyte size, while expressions in voltage-gated potassium channels (Kv1.5 and Kv2.1) and angiogenic factors (angiopoietin-2 and vascular endothelial growth factor) were decreased. Right ventricular expressions of pro-inflammatory cytokines [interleukin (IL)-1α, IL-1β, tumour necrosis factor-α (TNF-α)] and natriuretic peptide precursors (NPPA and NPPB) were increased. There was an inverse correlation between RV Ees/Ea and pro-apoptotic Bax/Bcl-2 ratios.

CONCLUSIONS

Prolonged left-to-right shunting in piglets does not further aggravate pulmonary vasculopathy, but is a cause of RV failure, which appears related to an activation of apoptosis and inflammation.

Gene therapy for pulmonary hypertension: prospects and challenges

INTRODUCTION

Recent evidence shows that pulmonary arterial hypertension (PAH) remains a fatal disease despite the introduction of new pharmacological treatments. New options are therefore needed and gene therapy approaches are a rational consideration based on emerging understanding of the genetic basis of PAH.

AREAS COVERED

This review briefly discusses the recent developments in clinical management of PAH and the investigation of gene delivery techniques for pulmonary vascular disease from 1997 to 2010, relating this to improved understanding of disease pathogenesis during this period. There is a focus on bone morphogenetic protein receptor type 2, as mutations in this gene are clearly linked to disease pathogenesis and outcomes. The reader will gain insight into the gene vector strategies being used, the target cells and the specific genes being delivered as candidate therapeutic approaches for PAH.

EXPERT OPINION

Various genes and strategies for delivery have achieved improvements in PAH in animal models, which is encouraging for the development of this technology for human application. The main limiting factor for clinical progress relates to gene delivery vector technology.

Unrecognized glucose intolerance is common in pulmonary arterial hypertension

BACKGROUND

Animal and human data suggest insulin resistance is common in pulmonary arterial hypertension (PAH). Although routine assessment of insulin resistance is difficult, hemoglobin A(1c) (HbA(1c)) is a sensitive test to detect diabetes mellitus (DM) and those at high risk for DM. We aimed to define the prevalence of elevated HbA(1c) in PAH patients and to correlate HbA(1c) levels with functional assessment.

METHODS

HbA(1c) was measured in 41 PAH patients without a diagnosis of DM, along with demographic, functional, and hemodynamic data. Using published criteria, HbA(1c) ≤ 5.9% defined normal, 6.0% to 6.4% was glucose intolerance, and ≥ 6.5% was DM.

RESULTS

Twenty-three patients (56%) had HbA(1c) ≥ 6.0%, and 6 (15%) had unrecognized DM (HbA(1c) ≥ 6.5%). Age and body mass index were similar in patients with HbA(1c) ≥ 6.0% vs < 6.0%. There was a trend towards lower mean 6-minute walk distance in patients with elevated HbA(1c) (331.0 ± 126.6 vs 413.6 ± 74.9 meters, p = 0.07). The 6-month event-free survival was not significantly different in patients with elevated HbA(1c).

CONCLUSIONS

Unrecognized glucose intolerance as assessed by HbA(1c) is common in PAH. Further studies are needed to discern if glucose or insulin dysregulation mediates PAH pathogenesis or is secondary to advanced PAH.

Prostacyclins in pulmonary arterial hypertension: the need for earlier therapy

Pulmonary arterial hypertension (PAH) is a rare but serious condition, which if untreated, is associated with a 2-3-year median survival time. A number of treatment options are available for PAH, leading to improvements in exercise capacity, symptoms, and hemodynamics. However, the disease remains incurable and most patients will ultimately progress to right heart failure and death. Three classes of drugs are currently available to improve PAH outcomes, although this review will focus solely on a class of potent vasodilators known as prostacyclins. Currently, four prostacyclin analogs are licensed for the treatment of PAH: epoprostenol, treprostinil, and iloprost in the USA and some European countries, and beraprost in Japan and Korea. Prostacyclins have become the treatment of choice in patients with severe PAH, but there is also evidence to suggest that their earlier use may also benefit patients with mild-to-moderate disease. This review discusses the advantages of prostacyclins in terms of their usefulness in patients whose condition has deteriorated following monotherapy with other agents, and their integral role in combination therapy. The latter appears to offer the potential for pulmonary vasculature remodeling and could be regarded as an emerging paradigm to treat and prevent the progression of PAH.

Sex hormones are associated with right ventricular structure and function: The MESA-right ventricle study

RATIONALE

Sex hormones have effects on the left ventricle, but hormonal influences on the right ventricle (RV) are unknown.

OBJECTIVES

We hypothesized that sex hormones would be associated with RV morphology in a large cohort free of cardiovascular disease.

METHODS

Sex hormones were measured by immunoassay and RV ejection fraction (RVEF), stroke volume (RVSV), mass, end-diastolic volume, and end-systolic volume (RVESV) were measured by cardiac magnetic resonance imaging in 1,957 men and 1,738 postmenopausal women. The relationship between each hormone and RV parameter was assessed by multivariate linear regression.

MEASUREMENTS AND MAIN RESULTS

Higher estradiol levels were associated with higher RVEF (β per 1 ln[nmol/L], 0.88; 95% confidence interval [CI], 0.32 to 1.43; P = 0.002) and lower RVESV (β per 1 ln[nmol/L], -0.87; 95% CI, -1.67 to -0.08; P = 0.03) in women using hormone therapy. In men, higher bioavailable testosterone levels were associated with higher RVSV (β per 1 ln[nmol/L], 1.97; 95% CI, 0.20 to 3.73; P = 0.03) and greater RV mass and volumes (P ≤ 0.01). Higher dehydroepiandrosterone levels were associated with higher RVSV (β per 1 ln[nmol/L], 1.37; 95% CI, 0.15 to 2.59; P = 0.03) and greater RV mass (β per 1 ln[nmol/L], 0.25; 95% CI, 0.00 to 0.49; P = 0.05) and volumes (P ≤ 0.001) in women.

CONCLUSIONS

Higher estradiol levels were associated with better RV systolic function in women using hormone therapy. Higher levels of androgens were associated with greater RV mass and volumes in both sexes.

Survival of Chinese patients with pulmonary arterial hypertension in the modern treatment era

BACKGROUND

In a previous study of Chinese patients with idiopathic pulmonary arterial hypertension (IPAH) in the nontargeted therapy era (defined as the time before 2006 when new pulmonary arterial hypertension-specific drugs were not available in China), we reported 1- and 3-year survival estimates of only 68% and 39%, respectively. However, it is not yet known whether the survival of patients with pulmonary arterial hypertension is improved in the modern treatment era (defined in China as after 2006).

METHODS

A retrospective cohort study was undertaken in 276 consecutive patients with newly diagnosed incident IPAH and connective tissue disease-related pulmonary arterial hypertension (CTDPAH) who were referred between 2007 and 2009. Baseline characteristics and survival rates in the two groups were compared.

RESULTS

The 1- and 3-year survival estimates were 92.1% and 75.1%, respectively, in patients with IPAH, and 85.4% and 53.6%, respectively, in patients with CTDPAH. Patients with CTDPAH had a significantly lower mean pulmonary artery pressure, more pericardial effusion, and more severe impairment of the diffusion capacity of the lung for carbon monoxide than patients with IPAH. A diagnosis of CTDPAH, World Health Organization functional class III or IV, single-breath diffusion capacity of the lung for carbon monoxide < 80% predicted, and the presence of pericardial effusion were independent predictors of mortality. The 1- and 3-year survival rates of male patients were 93.5% and 77.5%, respectively, in those with IPAH, and 71.1% and 47.4%, respectively, in those with CTDPAH.

CONCLUSIONS

The survival rates of patients with pulmonary arterial hypertension have improved in China in the modern treatment era, despite the high costs of treatment and financial constraints. However, the survival rates of patients with CTDPAH are inferior to those of patients with IPAH. Our study also indicates poorer survival rates in male patients with CTDPAH.

[Pulmonary circulation: what has 2010 brought?]

In both thromboembolic disease and pulmonary hypertension, 2010 has been a prodigious year for interesting publications. Some data have helped to elucidate the factors associated with a greater risk of thromboembolic disease, such as long journeys and certain polymorphisms. New recommendations on diagnosis have been made, giving a greater role to computed tomography angiography. Magnetic resonance imaging is also gaining ground. More accurate risk evaluation is one of the objectives of the new guidelines of the European Society of Cardiology, which substitute some terms such as massive or submassive for high- and low-risk. Maintaining anticoagulation indefinitely in idiopathic pulmonary thromboembolism is recommended. Evidence on the efficacy of new drugs such as rivaroxaban, dabigatran and indraparinux is beginning to appear. In pulmonary hypertension, smoking seems to play a role as a risk factor. Some registries indicate that new treatments have not improved survival. Greater knowledge has been gained of the role of inflammation in the pathogenesis of the disease and a Spanish study supports the role of the 6-minute walk test in patient evaluation. Some drugs are highlighted in the literature. Imatinib is promising but probably only in some patients. Riociguat provides good results and inhaled treprostinil has emerged as a new option.

Serotonin transporter, sex, and hypoxia: microarray analysis in the pulmonary arteries of mice identifies genes with relevance to human PAH

Pulmonary arterial hypertension (PAH) is up to threefold more prevalent in women than men. Female mice overexpressing the serotonin transporter (SERT; SERT+ mice) exhibit PAH and exaggerated hypoxia-induced PAH, whereas male SERT+ mice remain unaffected. To further investigate these sex differences, microarray analysis was performed in the pulmonary arteries of normoxic and chronically hypoxic female and male SERT+ mice. Quantitative RT-PCR analysis was employed for validation of the microarray data. In relevant groups, immunoblotting was performed for genes of interest (CEBPβ, CYP1B1, and FOS). To translate clinical relevance to our findings, CEBPβ, CYP1B1, and FOS mRNA and protein expression was assessed in pulmonary artery smooth muscle cells (PASMCs) derived from idiopathic PAH (IPAH) patients and controls. In female SERT+ mice, multiple pathways with relevance to PAH were altered. This was also observed in chronically hypoxic female SERT+ mice. We selected 10 genes of interest for qRT-PCR analysis (FOS, CEBPβ, CYP1B1, MYL3, HAMP2, LTF, PLN, NPPA, UCP1, and C1S), and 100% concordance was reported. Protein expression of three selected genes, CEBPβ, CYP1B1, FOS, was also upregulated in female SERT+ mice. Serotonin and 17β-estradiol increased CEBPβ, CYP1B1, and FOS protein expression in PASMCs. In addition, CEBPβ, CYP1B1, and FOS mRNA and protein expression was also increased in PASMCs derived from IPAH patients. Here, we have identified a number of genes that may predispose female SERT+ mice to PAH, and these findings may also be relevant to human PAH.

The potential for inhaled treprostinil in the treatment of pulmonary arterial hypertension

Inhaled treprostinil is a safe and well-tolerated approved pharmaceutical for the treatment of pulmonary arterial hypertension. In a series of open-label studies and in the pivotal trial with 253 patients, this long-acting prostacyclin analogue demonstrated pronounced pulmonary selectivity of vasodilatory effects, improved physical capacity and excellent tolerability and safety following aerosol administration. For efficient treatment, only four daily inhalations of treprostinil are necessary compared with six to nine in iloprost aerosol therapy. This review describes in detail the development of inhaled treprostinil, starting with intravenous epoprostenol followed by inhaled iloprost and subcutaneous treprostinil, all three representing well-established and widely approved prostanoid therapies for pulmonary hypertension.

In order to circumvent the drawbacks of intravenous epoprostenol, stable prostacyclin analogues with similar pharmacological properties have been investigated. In addition, alternative routes of administration have been proposed and evaluated, mainly inhaled and subcutaneous delivery. The concept of inhaled treprostinil was to combine the pulmonary selectivity of an aerosolized vasodilator with the long-acting effects of a stable prostacyclin analogue.

Pulmonary arterial hypertension remains, however, a severe, life-threatening disease, in spite of the enormous progress in specific drug therapy over the last decade. Therefore, further improvement of drug therapy will be essential, with clear potential for inhaled treprostinil: a reduction of inhalation frequency and duration would markedly improve quality of life and compliance, and a longer-lasting local prostanoid effect might further enhance the efficacy of inhaled treprostinil. The advantageous pharmacological properties of treprostinil offer the opportunity to establish a convenient metered dose inhaler as a delivery system, to combine inhaled treprostinil with available or future drugs for pulmonary arterial hypertension, or to develop sustained release formulations of treprostinil suitable for inhalation based on liposomes or biodegradable nanoparticles.

Bosentan for the treatment of adult pulmonary hypertension

Pulmonary hypertension is a severe progressive disease with a marked morbidity and a high mortality attributed to right heart failure. Bosentan, a dual endothelin receptor antagonist, is an effective and well-tolerated oral therapy for the management of pulmonary arterial hypertension (PAH; WHO group 1 pulmonary hypertension). Bosentan improves cardiopulmonary hemodynamics, exercise capacity, WHO functional class and quality of life, as well as delaying time to clinical worsening in patients with PAH. This article reviews the role of endothelin-1 in the pathogenesis and progression of PAH, the diagnosis of PAH and the pharmacology of bosentan, and summarizes the current available evidence for the safety and efficacy of bosentan for the treatment of PAH as a monotherapy and combination therapy, as well as its role in the management of other forms of pulmonary hypertension.

Viruses in pharmaceutical research: pulmonary vascular disease

The management and understanding of pulmonary arterial hypertension (PAH) has undergone something of a revolution in the last 10 years, with new pharmacological agents entering routine clinical practice and significantly improving outcomes. Nevertheless many patients ultimately progress, and additional new treatment approaches are needed. There is now greater understanding of the molecular and genetic basis for the development of PAH, specifically in regard to the role of bone morphogenetic protein receptor 2 (BMPR2) signaling and related pathways. The challenge is to determine whether these new discoveries can be exploited for new therapies. In this article the role of viruses as tools for gene delivery for pulmonary vascular disease is discussed. Gene delivery of BMPR2 has now been shown to ameliorate the development and progression of PAH in animal models, thereby identifying this approach as a therapeutic target.

Factors affecting the response to exercise in patients with severe pulmonary arterial hypertension

INTRODUCTION

Ergospirometry objectively quantifies exercise capacity. Up until now, the response to exercise evaluated by ergospirometry in patients with pulmonary arterial hypertension has only been described in recently diagnosed.patients. Our aim is to describe the response to exercise in patients with severe pulmonary arterial hypertension under specific treatment and define which parameters determine their exercise capacity.

PATIENTS AND METHOD

A cross-sectional study was performed on 80 patients, 57 women, aged 45 (14), with severe pulmonary arterial hypertension (48 idiopathic, 14 related to toxic rapeseed oil, 13 to connective tissue disease, 5 to human immunodeficiency virus), mean pulmonary pressure at diagnosis 61(15)mmHg and after 49(33) months under treatment since diagnosis. Biomarkers were measured and echocardiography and ergospirometry were performed the same day.

RESULTS

Our patients, under specific treatment, showed the typical behaviour of patients with pulmonary arterial hypertension with less limitation of both aerobic capacity and ventilatory efficiency. Being male (p=0.004), high ventilatory equivalent for carbon dioxide at anaerobic threshold (p<0.001) or biomarkers (p=0.006) were the strongest predictors of impaired peak oxygen uptake in multivariate analysis, whereas for an impaired percentage achieved of predicted value were right ventricle diastolic diameter (p<0.001), months of treatment (p=0.01) and high ventilatory equivalent for CO(2) (p<0.001).

CONCLUSIONS

In pulmonary arterial hypertension, right ventricle dysfunction (expressed by its dilation or high NTproBNP) and impaired ventilatory inefficiency as well as being male or a short time under treatment can be considered as determining factors of impaired exercise capacity.

Integration of clinical and hemodynamic parameters in the prediction of long-term survival in patients with pulmonary arterial hypertension

BACKGROUND

Current management guidelines for pulmonary arterial hypertension (PAH) recommend a treatment choice based primarily on World Health Organization (WHO) functional class. This study was designed to assess how the incorporation of readily obtained clinical and test-based information may significantly improve the prediction of outcomes over functional class alone.

METHODS

Clinical and hemodynamic variables were assessed in 484 consecutive patients presenting with WHO group 1 PAH. The primary outcome measure was time to all-cause mortality over 5 years from the index presentation (data available in all). Follow-up was censored at the time of lung or heart/lung transplant in 21 patients or at 5 years. Predictors of mortality were assessed sequentially using Cox models, with the step-wise incorporation of clinical variables, echocardiographic, and catheterization findings. Results were further compared with the REVEAL (Registry to Evaluate Early and Long-term Pulmonary Arterial Hypertension Disease Management) prediction score.

RESULTS

Overall median survival was 237 weeks (95% CI, 196-266), corresponding to 1-year, 3-year, and 5-year survival rates of 81.1% (77.0, 84.7), 61.1% (56.5, 65.3), and 47.9% (43.2, 52.4), respectively. The prediction of mortality was improved incrementally by incorporating clinical and echocardiographic measures with a concordance index (c-index) of 0.84 compared with that of 0.60 with functional class alone. The REVEAL prediction score was validated independently in this cohort to predict both 1-year and 5-year mortality. It had a prediction c-index of 0.71.

CONCLUSIONS

The integration of routine PAH clinical (predominantly noninvasive) parameters predicts long-term outcome better than functional class and, hence, should be incorporated into medical management decisions.

Metabolic and hormonal derangements in pulmonary hypertension: from mouse to man

Pulmonary arterial hypertension (PAH) is a complex disease with significant morbidity and mortality. Recent animal and human studies have highlighted abnormalities in regulation and metabolism of insulin, sex hormones, adipokines and lipids that may play a role in disease development. Mouse studies suggest features of the metabolic syndrome (MS) including insulin resistance, deficiencies in peroxisome proliferator-activated receptor γ and apolipoprotein E, and low adiponectin are linked to development of PAH. In humans, insulin resistance, the MS and low levels of high-density lipoprotein have been associated with PAH. In addition, abnormal metabolism of oestrogens has been demonstrated in human and animal models of PAH, suggesting an important relationship of sex hormones and pulmonary vascular disease. Improved understanding of how metabolic and hormonal derangements relate to development and progression of pulmonary hypertension may lead to better disease therapies and understanding of potential risk factors. This review will focus on the animal and human data regarding metabolic and sex hormone derangements in PAH.

Survival in schistosomiasis-associated pulmonary arterial hypertension

OBJECTIVES

The objective of this study was to evaluate the natural history of untreated schistosomiasis-associated pulmonary arterial hypertension (Sch-PAH) patients as compared to idiopathic pulmonary arterial hypertension (IPAH) with respect to hemodynamics recorded at presentation and 36 months survival.

BACKGROUND

Schistosomiasis (Sch) is one of the most prevalent chronic infectious diseases in the world. Nevertheless data regarding one of its most severe clinical complications, pulmonary arterial hypertension (PAH), is scarce.

METHODS

We retrospectively analyzed case notes of all consecutive patients diagnosed of Sch-PAH and IPAH referred to the Heart Institute in São Paulo, Brazil, between 2004 and 2008. None of the Sch-PAH received PAH specific treatment whereas all IPAH patients did.

RESULTS

Sch-PH patients (n = 54) had less severe pulmonary hypertension as evidenced by lower levels of pulmonary vascular resistance (11.3 +/- 11.3 W vs. 16.7 +/- 10.6 W; p = 0.002) and mean pulmonary artery pressure (56.7 +/- 18.7 mm Hg vs. 64.6 +/- 17.4 mm Hg; p = 0.01) and higher cardiac output (4.62 +/- 1.5 l/min vs. 3.87 +/- 1.5 l/min; p = 0.009) at presentation than IPAH patients (n = 95). None of the Sch-PAH patients demonstrated a positive response to acute vasodilator testing, whereas 16.2% of IPAH patients did (p = 0.015). Survival rates at 1, 2, and 3 years were 95.1%, 95.1%, and 85.9% and 95%, 86%, and 82%, for Sch-PAH and IPAH, respectively (p = 0.49). Both groups had a higher survival rate when compared to IPAH survival as estimated by the NIH equation (71%, 61%, and 52%, respectively).

CONCLUSIONS

Sch-PAH has a more benign clinical course than IPAH despite a lack of demonstrable acute vasoreactivity at hemodynamic evaluation.

Strategic plan for lung vascular research: An NHLBI-ORDR Workshop Report

The Division of Lung Diseases of the National Heart, Lung, and Blood Institute, with the Office of Rare Diseases Research, held a workshop to identify priority areas and strategic goals to enhance and accelerate research that will result in improved understanding of the lung vasculature, translational research needs, and ultimately the care of patients with pulmonary vascular diseases. Multidisciplinary experts with diverse experience in laboratory, translational, and clinical studies identified seven priority areas and discussed limitations in our current knowledge, technologies, and approaches. The focus for future research efforts include the following: (1) better characterizing vascular genotype-phenotype relationships and incorporating systems biology approaches when appropriate; (2) advancing our understanding of pulmonary vascular metabolic regulatory signaling in health and disease; (3) expanding our knowledge of the biologic relationships between the lung circulation and circulating elements, systemic vascular function, and right heart function and disease; (4) improving translational research for identifying disease-modifying therapies for the pulmonary hypertensive diseases; (5) establishing an appropriate and effective platform for advancing translational findings into clinical studies testing; and (6) developing the specific technologies and tools that will be enabling for these goals, such as question-guided imaging techniques and lung vascular investigator training programs. Recommendations from this workshop will be used within the Lung Vascular Biology and Disease Extramural Research Program for planning and strategic implementation purposes.

Absence of influence of gender and BMPR2 mutation type on clinical phenotypes of pulmonary arterial hypertension

Background

Previous studies indicate that patients with pulmonary arterial hypertension (PAH) carrying a mutation in the bone morphogenetic protein receptor type 2 (BMPR2) gene, develop the disease 10 years earlier than non-carriers, and have a more severe hemodynamic compromise at diagnosis. A recent report has suggested that this may only be the case for females and that patients with missense mutations in BMPR2 gene have more severe disease than patients with truncating mutations.

Methods

We reviewed data from all patients with PAH considered as idiopathic and patients with a family history of PAH, who underwent genetic counselling in the French PAH network between January, 1^st 2004 and April, 1^st 2010. We compared clinical, functional, and hemodynamic characteristics between carriers and non-carriers of a BMPR2 mutation, according to gender or BMPR2 mutation type.

Results

PAH patients carrying a BMPR2 mutation (n = 115) were significantly younger at diagnosis than non-carriers (n = 267) (35.8 ± 15.4 and 47.5 ± 16.2 respectively, p < 0.0001). The presence of a BMPR2 mutation was associated with a younger age at diagnosis in females (36.4 ± 14.9 in BMPR2 mutation carriers and 47.4 ± 15.8 in non-carriers, p < 0.0001), and males (34.6 ± 16.8 in BMPR2 mutation carriers and 47.8 ± 17.1 in non-carriers, p < 0.0001). BMPR2 mutation carriers had a more severe hemodynamic compromise at diagnosis, but this was not influenced by gender. No differences in survival and time to death or lung transplantation were found in male and female PAH patients carrying a BMPR2 mutation. No differences were observed in clinical outcomes according to the type of BMPR2 mutations (missense, truncating, large rearrangement or splice defect).

Conclusion

When compared to non-carriers, BMPR2 mutation carriers from the French PAH network are younger at diagnosis and present with a more severe hemodynamic compromise, irrespective of gender. Moreover, BMPR2 mutation type had no influence on clinical phenotypes in our patient population.