Clinical effects of endothelin receptor antagonism with bosentan in patients with severe chronic heart failure: results of a pilot study

Saudi Guidelines on the Diagnosis and Treatment of Pulmonary Hypertension: Pulmonary hypertension due to left heart disease

Pulmonary hypertension (PH) due to left heart disease is the most common cause of pulmonary hypertension in the western world. It is classified as WHO PH group II. Different pathophysiologic abnormalities may take place in this condition, including pulmonary venous congestion and vascular remodeling. Despite the high prevalence of WHO group 2 PH, the major focus of research on PH over the past decade has been on WHO group 1 pulmonary arterial hypertension (PAH). Few investigators have focused on WHO group 2 PH; consequently, the pathophysiology of this condition remains poorly understood, and no specific therapy is available. Clinical and translational studies in this area are much needed and have the potential to positively affect large numbers of patients. In this review, we provide a detailed discussion upon the pathophysiology of the disease, the recent updates in classification, and the diagnostic and therapeutic algorithms.

Current state of endothelin receptor antagonism in hypertension and pulmonary hypertension

Endothelin 1 (ET-1), a potent vasoconstrictive substance, was discovered in 1988 by Yanagisawa and colleagues, and since then, a quarter of a century has passed. Understanding the biology of ET-1 has rapidly developed by characterizing the components of its receptors and processing enzymes. Numerous studies have revealed not only physiological but also various pathophysiological roles of the ET system. At first, ET-1 was the attractive and promising target for the treatment of hypertension owing to its potent vasoconstrictive nature and a variety of ET receptor antagonists (ERAs) were studied. However, the clinical application to treat hypertension was disappointing because of the side effects, including liver toxicity and fluid retention. On the other hand, ERAs have been established as orphan drugs for the treatment of pulmonary arterial hypertension and improved the prognosis of patients. Furthermore, multipotency of the ET system in the pathogenesis of multiple diseases has led to the development of translational research not only in the field of hypertension but in a variety of fields. Furthermore, a range of studies are ongoing to apply ERAs to clinical situations. In this article, we review the pathophysiological roles of the ET system in hypertension and pulmonary hypertension and the potential of ET receptor antagonism for the treatment of these diseases.

Pathophysiology and potential treatments of pulmonary hypertension due to systolic left heart failure

Pulmonary hypertension (PH) due to left heart failure is becoming increasingly prevalent and is associated with poor outcome. The precise pathophysiological mechanisms behind PH due to left heart failure are, however, still unclear. In its early course, PH is caused by increased left ventricular filling pressures, without pulmonary vessel abnormalities. Conventional treatment for heart failure may partly reverse such passive PH by optimizing left ventricular function. However, if increased pulmonary pressures persist, endothelial damage, excessive vasoconstriction and structural changes in the pulmonary vasculature may occur. There is, at present, no recommended medical treatment for this active component of PH due to left heart failure. However, as the vascular changes in PH due to left heart failure may be similar to those in pulmonary arterial hypertension (PAH), a selected group of these patients may benefit from PAH treatment targeting the endothelin, nitric oxide or prostacyclin pathways. Such potent pulmonary vasodilators could, however, be detrimental in patients with left heart failure without pulmonary vascular pathology, as selective pulmonary vasodilatation may lead to further congestion in the pulmonary circuit, resulting in pulmonary oedema. The use of PAH therapies is therefore currently not recommended and would require the selection of suitable patients based on the underlying causes of the disease and careful monitoring of their progress. The present review focuses on the following: (i) the pathophysiology behind PH resulting from systolic left heart failure, and (ii) the current evidence for medical treatment of this condition, especially the role of PAH-targeted therapies in systolic left heart failure.

Emerging drugs for chronic kidney disease

INTRODUCTION

Chronic kidney disease (CKD) is a worldwide health problem. Despite remarkable headway in slowing the progression of kidney diseases, the incidence of end-stage renal disease (ESRD) is increasing in all countries with a severe impact on patients and society. The high incidence of diabetes and hypertension, along with the aging population, may partially explain this growth. Currently, the mainstay of pharmacological treatment for CKD, aiming to slow progression to ESRD are ACE inhibitors and angiotensin II receptor blockers for their hemodynamic/antihypertensive and anti-inflammatory/antifibrotic action. However, novel drugs would be highly desirable to effectively slow the progressive renal function loss.

AREAS COVERED

Through the search engines, PubMed and ClinicalTrial.gov, the scientific literature was reviewed in search of emerging drugs in Phase II or III trials, which appear to be the most promising for CKD treatment.

EXPERT OPINION

The great expectations for new drugs for the management of CKD over the last decade have unfortunately not been met. Encouraging results from preliminary studies with specific agents need to be tempered with caution, given the absence of consistent and adequate data. To date, several agents that showed great promise in animal studies have been less effective in humans.

Lung capillary injury and repair in left heart disease: a new target for therapy?

The lungs are the primary organs affected in LHD (left heart disease). Increased left atrial pressure leads to pulmonary alveolar–capillary stress failure, resulting in cycles of alveolar wall injury and repair. The reparative process causes the proliferation of MYFs (myofibroblasts) with fibrosis and extracellular matrix deposition, resulting in thickening of the alveolar wall. Although the resultant reduction in vascular permeability is initially protective against pulmonary oedema, the process becomes maladaptive causing a restrictive lung syndrome with impaired gas exchange. This pathological process may also contribute to PH (pulmonary hypertension) due to LHD. Few clinical trials have specifically evaluated lung structural remodelling and the effect of related therapies in LHD. Currently approved treatment for chronic HF (heart failure) may have direct beneficial effects on lung structural remodelling. In the future, novel therapies specifically targeting the remodelling processes may potentially be utilized. In the present review, we summarize data supporting the clinical importance and pathophysiological mechanisms of lung structural remodelling in LHD and propose that this pathophysiological process should be explored further in pre-clinical studies and future therapeutic trials.

Pulmonary hypertension due to left heart diseases

Pulmonary hypertension (PH), a common complication of left heart diseases (LHD), negatively impacts symptoms, exercise capacity, and outcome. Although the true prevalence of PH-LHD is unknown, a subset of patients might present significant PH that cannot be explained by a passive increase in left-sided filling pressures. The term "out-of-proportion" PH has been used to identify that population without a clear definition, which has been found less than ideal and created confusion. We propose a change in terminology and a new definition of PH due to LHD. We suggest to abandon "out-of-proportion" PH and to distinguish "isolated post-capillary PH" from "post-capillary PH with a pre-capillary component" on the basis of the pressure difference between diastolic pulmonary artery pressure and pulmonary artery wedge pressure. Although there is no validated treatment for PH-LHD, we provide insights into management and discuss completed and randomized trials in this condition. Finally, we provide recommendations for future clinical trials to establish safety and efficacy of novel compounds to target this area of unmet medical need.

Pharmacologic treatments for pulmonary hypertension: exploring pharmacogenomics

Pulmonary hypertension (PH) is a disease with multiple etiologies and is categorized into five broad groups. Of these groups, pulmonary arterial hypertension (PAH) is the most studied and, therefore, all of the currently available drug classes (prostacyclin analogs, endothelin receptor antagonists and phosphodiesterase type 5 inhibitors) were developed to treat PAH. Thus, limited treatment data exist for the less-studied non-PAH forms of PH. Pharmacogenomics can be a tool to better understand the pathways involved in PH, as well as to improve personalization of therapy. However, little pharmacogenomic research has been carried out on this disease. New treatments for PH are on the horizon, deriving from both repurposed currently available drugs and novel therapeutics.

Poor agreement between pulmonary capillary wedge pressure and left ventricular end-diastolic pressure in a veteran population

Background

Accurate determination of left ventricular filling pressure is essential for differentiation of pre-capillary pulmonary hypertension (PH) from pulmonary venous hypertension (PVH). Previous data suggest only a poor correlation between left ventricular end-diastolic pressure (LVEDP) and its commonly used surrogate, the pulmonary capillary wedge pressure (PCWP). However, no data exist on the diagnostic accuracy of PCWP in veterans. Furthermore, the effects of age and comorbidities on the PCWP-LVEDP relationship remain unknown.

Methods

We investigated the PCWP-LVEDP relationship in 101 patients undergoing simultaneous right and left heart catherization at a large VA hospital. PCWP performance was evaluated using correlation and Bland-Altman analyses. Area under Receiver Operating Characteristics curves (AUROC) for PCWP were determined.

Results

PCWP-LVEDP correlation was moderate (r = 0.57). PCWP-LVEDP calibration was poor (Bland-Altman limits of agreement −17.2 to 11.4 mmHg; mean bias −2.87 mmHg). 59 patients (58.4%) had pulmonary hypertension; 15 (25.4%) of those met pre-capillary PH criteria based on PCWP. However, if LVEDP was used instead of PCWP, 7/15 patients (46.6%) met criteria for PVH rather than pre-capillary PH. When restricting analysis to patients with a mean pulmonary artery pressure of ≥25 mmHg and pulmonary vascular resistance of >3 Wood units (n = 22), 10 patients (45.4%) were classified as pre-capillary PH based on PCWP ≤15 mmHg. However, if LVEDP was used, 4/10 patients (40%) were reclassified as PVH. Among patients with any type of pulmonary hypertension, PCWP discriminated moderately between high and normal LVEDP (AUROC, 0.81; 95%CI 0.69–0.94). PCWP-LVEDP correlation was particularly poor in patients with COPD or obesity.

Conclusion

Reliance on PCWP rather than LVEDP results in misclassification of veterans as having pre-capillary PH rather than PVH in almost 50% of cases. This is clinically relevant, as misclassification may lead to inappropriate therapies and adverse events.

WHO's in second?: A practical review of World Health Organization group 2 pulmonary hypertension

World Health Organization (WHO) group 2 pulmonary hypertension (PH) due to left-side heart disease (ie, heart failure or left-sided valvular heart disease) is the most common form of PH in western countries. Distinguishing patients with WHO group 2 PH, particularly the subset of patients with PH due to heart failure with preserved ejection fraction (HFpEF), from those with WHO group 1 pulmonary arterial hypertension (PAH) is challenging. Separating the two conditions is of vital importance because treatment strategies differ completely. Furthermore, therapies that are indicated for WHO group 1 PAH may be harmful in patients with WHO group 2 PH. We review the somewhat confusing PH nomenclature and the WHO classification system and rationale behind it. We then focus on left-side heart disorders that cause PH. An aging population and advances in the medical management of common cardiovascular disorders have caused the prevalence of heart failure to rise significantly, with more than one-half of patients having HFpEF. We review contemporary studies that focus on clinical and echocardiographic findings that help to distinguish HFpEF from PAH in the patient with PH. We discuss the typical, and sometimes atypical, hemodynamic profiles that characterize these two groups, review challenges in the interpretation of data obtained by right-sided heart catheterization, and highlight special maneuvers that may be required for accurate diagnosis. Finally, we review the largely disappointing studies on the use of PAH-specific therapies in patients with WHO group 2 PH, including the use of prostacyclins, endothelin receptor antagonists, and the more promising phosphodiesterase-5 inhibitors.

Pathophysiology of cardiorenal syndrome in decompensated heart failure: role of lung-right heart-kidney interaction

Cardiorenal syndrome (CRS) is defined as an interaction of cardiac disease with renal dysfunction that leads to diuretic resistance and renal function worsening, mainly with heart failure (HF) exacerbation. Hemodynamic variables linking heart and kidney are renal blood flow (cardiac output) and perfusion pressure, i.e., the aortic - renal venous pressure gradient. CRS has traditionally been interpreted as related to defective renal perfusion and arterial underfilling and, more recently, to elevation in central venous pressure transmitted back to renal veins. Our suggestion is that in a setting where aortic pressure is generally low, due to heart dysfunction and to vasodrepressive therapy, the elevated central venous pressure (CVP) contributes to lower the renal perfusion pressure below the threshold of kidney autoregulation (≤80mm Hg) and causes renal perfusion to become directly pressure dependent. This condition is associated with high neurohumoral activation and preglomerular vasoconstriction that may preserve pressure, but may decrease filtration fraction and glomerular filtration rate and enhance proximal tubular sodium absorption. Thus, congestion worsens and drives the vicious cycle of further sodium retention and HF exacerbation. Lowering CVP by targeting the lung-right heart interaction that sustains elevated CVP seems to be a more rational approach rather than reducing intravascular volume. This interaction is crucial and consists of a cascade with stepwise development of pulmonary post-capillary hypertension, precapillary arteriolar hypertone, right ventricular overload and enlargement with tricuspid incompetence and interference with left ventricular filling (interdependence). The resultant CVP rise is transmitted to the renal veins, eventually drives CRS and leads to a positive feedback loop evolving towards HF refractoriness.

Pulmonary hypertension in patients with chronic and end-stage kidney disease

Pulmonary hypertension is defined as a mean pulmonary artery pressure ≥25 mm Hg and is a recently recognized complication of chronic kidney disease and end-stage renal disease. There is significant epidemiological overlap with kidney disease and the underlying causes of World Health Organization group 1-4 pulmonary hypertension (pulmonary arteriopathy, left heart disease, chronic pulmonary disease, and chronic thromboembolic disease, respectively). In addition, an entity of 'unexplained pulmonary hypertension,' group 5, in patients with chronic kidney disease and end-stage renal disease has emerged, with prevalence estimates of 30-50%. The pathogenesis of pulmonary hypertension in this population is due to alterations in endothelial function, increased cardiac output, and myocardial dysfunction leading to elevated left heart filling pressure, with recent data suggesting that left heart dysfunction may account for the vast majority of pulmonary hypertension in patients with kidney disease. Pulmonary hypertension is an independent predictor of increased mortality in patients on dialysis and those undergoing kidney transplantation. This review summarizes what is known about the epidemiology, pathogenesis, transplantation outcomes, mortality, and treatment of pulmonary hypertension in patients with chronic kidney disease and end-stage renal disease.

Right ventricular pulmonary hypertension

In heart failure (HF) syndrome, the development of pulmonary hypertension (PH), right ventricular (RV) dysfunction and failure are ominous prognostic signs. Pathophysiology, clinical interest and targeted therapeutic approaches for left-sided PH and its consequences on RV function have been traditionally confined to advanced HF stages. Community- and population-based studies have clearly indicated that PH is frequent even in HF patients with preserved ejection fraction, and may carry important prognostic implications in normal ageing as well. HF guidelines are inconclusive on both preventive and curative strategies for left-sided PH and its consequences on RV function. The search for new therapeutic opportunities targeted on pulmonary vascular and right heart remodeling are an important challenge for the future.

Endothelin-2, the forgotten isoform: emerging role in the cardiovascular system, ovarian development, immunology and cancer

Endothelin-2 [ET-2; also known as vasoactive intestinal contractor (VIC), in rodents] differs from endothelin-1 (ET-1) by only two amino acids, and unlike the third isoform, endothelin-3 (ET-3), it has the same affinity as ET-1 for both ET(A) and ET(B) receptors. It is often assumed that ET-2 would mimic the actions of the more abundant ET-1 and current pharmacological interventions used to inhibit the ET system would also block the actions of ET-2. These assumptions have focused research on ET-1 with ET-2 studied in much less detail. Recent research suggests that our understanding of the ET family requires re-evaluation. Although ET-2 is very similar in structure as well as pharmacology to ET-1, and may co-exist in the same tissue compartments, there is converging evidence for an important and distinct ET-2 pathway. Specifically is has been demonstrated that ET-2 has a key role in ovarian physiology, with ET-2-mediated contraction proposed as a final signal facilitating ovulation. Furthermore, ET-2 may also have a pathophysiological role in heart failure, immunology and cancer. Comparison of ET-2 versus ET-1 mRNA expression suggests this may be accomplished at the level of gene expression but differences may also exist in peptide synthesis by enzymes such as endothelin converting enzymes (ECEs) and chymase, which may allow the two pathways to be distinguished pharmacologically and become separate drug targets. LINKED ARTICLES This article is part of a themed section on Endothelin. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.168.issue-1.

Effect of bosentan on pulmonary hypertension secondary to systolic heart failure

OBJECTIVES

The dual endothelin receptor antagonist bosentan improves pulmonary vascular resistance (PVR) in patients with primary pulmonary hypertension (PH). The effects of bosentan on secondary PH due to systolic heart failure (HF) are not well defined. This study evaluates the effect and tolerability of bosentan in patients with PH secondary to HF.

METHODS

Seventeen adult HF patients with PH and New York Heart Association class III-IV symptoms were treated with bosentan, 62.5 mg twice daily, for 1 month, which was gradually increased to 125 mg twice daily thereafter. Right heart catheterization (RHC), a clinical evaluation and echocardiographic measurements were performed at baseline and at 4 ± 3 (mean ± SD) months of follow-up. Response to bosentan was defined as an improvement in clinical, echocardiographic and RHC parameters.

RESULTS

Six patients did not complete the study (therapy was discontinued due to hypotension, elevated liver enzymes or acute decompensation of HF), 11 patients completed the follow-up; 9 patients responded to therapy. Systemic arterial pressures, pulmonary pressures, PVR and the transpulmonary gradient significantly decreased compared with baseline levels in 9 responders (p = 0.05, 0.05, 0.01 and 0.004, respectively), and 4 became eligible for heart transplantation and 3 for left ventricular assist device implantation.

CONCLUSIONS

Bosentan decreased pulmonary pressures and PVR in the majority of patients with PH secondary to systolic HF, thereby allowing them to be considered candidates for heart transplantation.

Pulmonary hypertension due to left heart disease: updated Recommendations of the Cologne Consensus Conference 2011

The 2009 European Guidelines on Diagnosis and Treatment of Pulmonary Hypertension (PH) have been adopted for Germany. While the guidelines contain detailed recommendations regarding pulmonary arterial hypertension (PAH), they contain only a relatively short paragraph on other, much more frequent forms of PH including PH owing to left heart disease. The guidelines point out that the drugs currently used to treat patients with PAH (prostanoids, endothelin receptor antagonists and phosphodiesterase type 5 inhibitors) have not been sufficiently investigated in other forms of PH. However, despite the lack of respective efficacy data an uncritical use of targeted PAH drugs in patients with PH associated with left heart disease is currently observed at an increasing rate. This development is a matter of concern. On the other hand, PH is a frequent problem that is highly relevant for morbidity and mortality in patients with left heart disease. It that sense, the practical implementation of the European Guidelines in Germany requires the consideration of several specific issues and already existing novel data. This requires a detailed commentary to the guidelines, and in some aspects an update already appears necessary. In June 2010, a Consensus Conference organized by the PH working groups of the German Society of Cardiology (DGK), the German Society of Respiratory Medicine (DGP) and the German Society of Pediatric Cardiology (DGPK) was held in Cologne, Germany. This conference aimed to solve practical and controversial issues surrounding the implementation of the European Guidelines in Germany. To this end, a number of working groups was initiated, one of which was specifically dedicated to PH due to left heart disease. This commentary describes in detail the results and recommendations of the working group which were last updated in October 2011.

Treatment for pulmonary hypertension of left heart disease

OPINION STATEMENT

Pulmonary hypertension (PH) secondary to left heart disease is a largely underestimated target of therapy. Except for a specific focus on PH consequences in patients with advanced heart failure (HF) receiving a left ventricular mechanical assist device or candidates for transplantation, prevention and treatment of initial subclinical forms of PH are not considered a priority in the management of this chronic disease population. Nonetheless, there is recent growing evidence supporting a clinical and prognostic role of PH in the elderly and in HF with preserved ejection fraction (pEF). Studies have defined PH-HFpEF as a new entity typically defining the evolving nature of disease. Although the prevalence of PH in these populations is not well-defined, the potential for effective pharmacological approaches that might impact the natural history of the disease starting from earlier stages is promising. However, it should be recognized that pharmacological studies performed to date with traditional pulmonary vasodilators in cohorts with HF and left-sided PH have not been positive, primarily because of concomitant systemic hypotension and hepatic side effects. This evidence along with the lack of studies specifically performed in the elderly and HFpEF often lead Guidelines to give neutral recommendations or even arbitrary assumptions. Recent availability of selective well-tolerated pulmonary vasodilators, such as phosphodiesterase type 5 (PDE5) inhibitors, however, seem to offer a solid background for treating left-sided PH at both early and later stages of the disease process.

Pulmonary hypertension and right ventricular failure in left ventricular systolic dysfunction

PURPOSE OF REVIEW

Pulmonary hypertension and right ventricular failure (RVF) in left ventricular systolic dysfunction (LVSD) is associated with high morbidity and mortality. This review presents an overview of the classification, pathophysiology, natural history, clinical features, prevention and treatment of this common clinical problem with a focus on the most recent studies. Many of the current evidence-based therapeutic agents for pulmonary hypertension in the absence of systolic or diastolic heart failure (e.g. prostaglandins, endothelin antagonists) are not efficacious in pulmonary hypertension with LVSD.

RECENT FINDINGS

Recent clinical evidence strongly supports an evolving role for phosphodiesterase type 5 (PDE5) inhibition in patients with pulmonary hypertension and LVSD. Chronic PDE5 inhibition in the short-to-intermediate duration studies to date significantly reduces pulmonary pressures and pulmonary vascular resistance (PVR), effects reverse right ventricle and left ventricle remodeling, improves ventilator efficiency, improves peak exercise capacity and improves quality of life in selected patients with stable, moderately symptomatic LVSD and pulmonary hypertension.

SUMMARY

Although long-term outcome studies are currently lacking, chronic PDE5 inhibition should be considered in carefully selected LVSD patients who manifest persistent significant elevation of pulmonary hypertension or PVR or uncontrolled RVF after aggressive management with all standard current evidence-based LVSD therapies (neurohormonal antagonists, diuretics and cardiac resynchronization in appropriate candidates).

Who needs a transplant and when?

PURPOSE OF REVIEW

Heart transplantation remains the treatment of choice for patients with advanced heart failure. We review the current definition of optimal therapy, prediction of prognosis and revisit contraindications for transplant.

RECENT FINDINGS

Clinical trials of eplerenone and ivabradine were associated with improved prognosis, whereas others (nesiritide) were disappointing. Advances in cardiac resynchronization therapy and ventricular assist devices (VAD) have resulted in an expansion of their indications. Advances in catheter ablation for ventricular tachycardia have made this an uncommon indication for heart transplantation. Surgical ventricular reconstruction and mitral valve intervention have not resulted in survival benefit. Bypass surgery was associated with a lower mortality from cardiovascular causes. Prognostic risk scores have been developed in heart failure patients; however, ongoing refinements are needed. Selected patients with diabetes, HIV and pretransplant malignancy, now have favourable outcomes after heart transplantation. VAD as bridge to candidacy is an option in heart failure patients with 'fixed' pulmonary hypertension. Alternate listing strategies have also been studied to provide high-risk patients with an opportunity for heart transplantation.

SUMMARY

Heart failure patients should be on current optimal medical and device therapy with a poor prognosis before consideration for heart transplantation. An individualized approach to heart transplantation assessment is recommended.

Clinical trials with endothelin receptor antagonists: what went wrong and where can we improve?

In the early 1990s, within three years of cloning of endothelin receptors, orally active endothelin receptor antagonists (ERAs) were tested in humans and the first clinical trial of ERA therapy in humans was published in 1995. ERAs were subsequently tested in clinical trials involving heart failure, pulmonary arterial hypertension, resistant arterial hypertension, stroke/subarachnoid hemorrhage and various forms of cancer. The results of most of these trials - except those for pulmonary arterial hypertension and scleroderma-related digital ulcers - were either negative or neutral. Problems with study design, patient selection, drug toxicity, and drug dosing have been used to explain or excuse failures. Currently, a number of pharmaceutical companies who had developed ERAs as drug candidates have discontinued clinical trials or further drug development. Given the problems with using ERAs in clinical medicine, at the Twelfth International Conference on Endothelin in Cambridge, UK, a panel discussion was held by clinicians actively involved in clinical development of ERA therapy in renal disease, systemic and pulmonary arterial hypertension, heart failure, and cancer. This article provides summaries from the panel discussion as well as personal perspectives of the panelists on how to proceed with further clinical testing of ERAs and guidance for researchers and decision makers in clinical drug development on where future research efforts might best be focused.

Bosentan in heart transplantation candidates with severe pulmonary hypertension: efficacy, safety and outcome after transplantation

BACKGROUND

Increased pulmonary vascular resistance (PVR) is associated with increased right ventricular failure and mortality after heart transplantation.

METHODS

In this prospective study, 22 patients considered high-risk candidates for heart transplantation because of severe pulmonary hypertension (PVR = 6 ± 2 Wood units; transpulmonary gradient 22 ± 7 mmHg), received bosentan 125 mg bid. Right heart catheterization was repeated after four months (n = 22) and 12 months (n = 9). Eleven patients who declined participation in the study were considered as control group.

RESULTS

After four months, PVR decreased by 38% in patients receiving bosentan (n = 22), while it increased by 25% in the control group (p = 0.001). Those patients who received bosentan for 12 months (n = 9), experienced a 60% reduction in PVR compared to baseline (p = 0.003). Only three patients (14%) had no hemodynamic improvement with bosentan. After bosentan therapy, 14 patients (64%) underwent heart transplantation. Patients with high PVR who received bosentan showed a trend toward better one-yr survival after transplantation than patients with PVR ≤ 2.5 Wood units transplanted in the same period of time (93% vs. 83%).

CONCLUSIONS

In patients considered high-risk candidates for heart transplantation because of high PVR, therapy with bosentan is associated with a significant reduction in PVR and a good outcome after transplantation.

Emerging therapies for heart failure: renal mechanisms and effects

Improved understanding of the pathophysiology of salt and water homeostasis has provided a foundation for explaining the renal mechanisms of emerging therapies for heart failure, as well as why renal function might potentially be improved or harmed. These aspects are reviewed in this article for a number of newer therapies including adenosine, endothelin, and vasopressin receptor antagonists, as well as extracorporeal ultrafiltration. An appreciation of the complexity and sometimes opposing pathways of these approaches may explain their limited efficacy in early trials, in which there has not been a substantial improvement in patient or renal outcomes. In that there is often a balance between beneficial and maladaptive receptor actions and neurohumoral responses, this physiologic approach also provides insight into the rationale for combining therapies. Multi-agent strategies may thus maximize their effectiveness while minimizing adverse effects and tolerance. In this paper, the theoretical impact of the emerging agents based on their mechanism of action and pathophysiology of the disease is initially addressed. Then, the available clinical evidence for each class of drugs is reviewed with special emphasis on their effect on kidney-related parameters. Finally, a general overview of the complexity of the interpretation of trials is offered along with a number of potential explanations for the observed results.

Antidiuretic effects of the endothelin receptor antagonist avosentan

Several clinical studies have investigated the potential benefits of endothelin receptor antagonism in chronic pathologies such as diabetic kidney disease. However, fluid retention and edema have been identified as major side effects of endothelin receptor antagonists. In the present study we hypothesized that avosentan which was described as a predominant ET_A receptor antagonist would produce fluid retention at high concentrations where non-specific blockade of ET_B receptors may occur. Incremental doses of the predominant ET_A receptor antagonist SPP301 (0.003; 0.03; 3 mg/kg) were administered intravenously to anesthetized Sprague-Dawley rats undergoing saline diuresis. Diuresis, glomerular filtration rate, and blood pressure (BP) were monitored. SPP301 decreased urine output (5.6; 34.8; 58.8% decrease from vehicle) and fractional excretion of water (5.7; 31.7; 56.4% decrease from vehicle) in a concentration-dependent manner. Glomerular filtration rate was unchanged while BP was reduced by 10 mmHg only by the highest dose of SPP301. Administration of the ET_B selective receptor antagonist BQ-788 (3 mg/kg) following SPP301 3 mg/kg did not further decrease urine output or water excretion and was without effect on glomerular filtration rate. These data indicate that increasing concentrations of SPP301 may also block ET_B receptors and cause antidiuresis. This effect could explain why fluid retention and edema occur during treatment with predominant ET_A receptor blockers.

Characterization of pulmonary venous hypertension patients with reactive pulmonary hypertension as compared to proportional pulmonary hypertension

BACKGROUND

Patients with pulmonary venous hypertension (PVH) secondary to left heart disease can be further classified according to their hemodynamic profile: pulmonary hypertension (PH) in proportion to the pulmonary capillary wedge pressure (PCWP) and PH out of proportion to the PCWP or reactive PH. Currently, there are no measures that enable prediction of the development of reactive PH in patients with left heart disease.

OBJECTIVES

In this study, we aim to characterize PVH patients with reactive PH as compared to proportional PH in an attempt to create a distinct profile for patients with left heart disease carrying a high risk for the development of reactive PH.

METHODS

Thirty-three PVH patients with reactive PH and 29 PVH patients with proportional PH were analyzed retrospectively over a 6-year period. Clinical, laboratory, echocardiographic and hemodynamic parameters were noted and compared between subgroups.

RESULTS

There was no significant difference between PVH patients with reactive and proportional PH with regard to gender, age (65.91 ± 11.9 vs. 66.69 ± 10.5 years) and body surface area (1.89 ± 0.24 vs. 1.9 ± 0.23 m(2)). Prevalence of the metabolic syndrome components was similar in both groups. Interestingly, PCWP was similar in both groups, as were the structural and functional parameters of the left heart.

CONCLUSIONS

PVH patients with reactive PH have a similar profile as patients with proportional PH; consequently, the evolution of reactive PH is unpredictable. Therefore, it is imperative that physicians maintain a high index of suspicion for the development of reactive PH even in the early stage of heart disease.

Current therapeutics and practical management strategies for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) develops from an abnormal interaction between the endothelium and smooth muscle cells in the pulmonary vasculature and is characterized by a progressive rise in pulmonary vascular resistance resulting from vascular remodeling, vasoconstriction, and cellular proliferation. Currently, 3 classes of drugs are approved for the treatment of PAH based on results from small short-term clinical trials-prostacyclin analogues, endothelin receptor antagonists, and phosphodiesterase type 5 inhibitors. The pharmacologic management of PAH is rapidly evolving as newer therapeutic targets that stabilize or reverse pulmonary vascular disease and target right ventricular function are being sought and as clinical practice patterns shift in favor of earlier diagnosis and aggressive treatment. This manuscript will review the practical management aspects of currently approved PAH treatments and briefly discuss combination therapy and novel pharmacologic targets. In addition, the treatment of acute right ventricular failure and evidence (or lack thereof) for therapies in non-PAH pulmonary hypertension, such as pulmonary hypertension from left side of the heart disease, are addressed.

Recent progress in the management of pulmonary hypertension

Pulmonary hypertension (PH) is a fatal disease caused by small pulmonary artery obstruction from vascular proliferation and remodeling. PH is characterized by elevated pulmonary arterial pressure and increased pulmonary vascular resistance, frequently leading to right-sided heart failure and death. The classification of PH has been recently updated to include 5 major categories of the disorder, are as: Group 1, pulmonary arterial hypertension (PAH); Group 2, PH due to left heart disease; Group 3, PH due to lung diseases and/or hypoxia; Group 4, chronic thromboembolic PH (CTEPH); and Group 5, others. Recently, significant progress has been made in the understanding of the pathophysiology, diagnosis and treatment of PH. Regarding the pathophysiology of the disorder, direct evidence for Rho-kinase activation in the pulmonary artery from PAH patients has been provided. Regarding diagnosis, optical coherence tomography is useful as a new differential diagnostic tool for distal type CTEPH vs. PAH. Regarding treatment, in addition to the conventional therapy, several new drugs are under clinical trial, including fasudil (a Rho-kinase inhibitor), riosiguat (a soluble guanylate cyclase activator), and imatinib (a tyrosine kinase inhibitor). In addition, pulmonary angioplasty and intensive immunosuppressive therapy may be effective for CTEPH and connective tissue disease-associated PAH, respectively. We briefly review the recent progress in the management of PH.

Pulmonary hypertension related to left-sided cardiac pathology

Pulmonary hypertension (PH) is the end result of a variety of diverse pathologic processes. The chronic elevation in pulmonary artery pressure often leads to right ventricular pressure overload and subsequent right ventricular failure. In patients with left-sided cardiac disease, PH is quite common and associated with increased morbidity and mortality. This article will review the literature as it pertains to the epidemiology, pathogenesis, and diagnosis of PH related to aortic valve disease, mitral valve disease, left ventricular systolic and diastolic dysfunction, and pulmonary veno-occlusive disease. Moreover, therapeutic strategies, which focus on treating the underlying cardiac pathology will be discussed.

Pharmacological treatment of chronic systolic heart failure: are we scraping the bottom of the barrel?

Heart failure is a major health problem and its prevalence is growing, primarily as a consequence of the aging of the population. Recently, we have witnessed significant progress in reducing the mortality associated with chronic heart failure due to the introduction of renin-angiotensin-aldosterone system inhibitors, beta-blocking agents and the use of electrical devices. However, the prognosis of heart failure is still so disappointing that it remains the leading cause of death in developed countries. This grim record impels the search for new therapeutic strategies. The objective of this paper is to briefly review the results of some recent trials that have been put in place to test the effects of drugs that are deemed to be potentially capable of improving the prognosis of chronic systolic heart failure patients. Despite compelling theoretical premises, the results to date appear to be weak or even disappointing.

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.

Current therapeutic approaches to pulmonary arterial hypertension

Pulmonary hypertension is a heterogeneous hemodynamic and pathophysiological state that is observed in a number of clinical conditions, which have been divided into six diagnostic groups. Although the increase in pulmonary pressure observed in these clinical groups may be similar, underlying disease mechanisms, diagnostic methods, and prognostic and therapeutic consequences are completely different. Pulmonary arterial hypertension is associated with several rare conditions that have comparable clinical and hemodynamic characteristics and exhibit virtually identical anatomical and pathological alterations in the lung microcirculation. These conditions include idiopathic and familial forms of the disease and disease forms associated with connective tissue disease, congenital heart defects involving systemic-to-pulmonary arterial shunts, portal hypertension, and HIV infection. It has been shown that treatment with specific drugs (e.g. prostanoids, endothelin-receptor antagonists and phosphodiesterase type-5 inhibitors) is effective in these patients and that these drugs can also be administered in various combinations. An evidence-based treatment algorithm has been developed for these patients. In patients with pulmonary hypertension due to left heart disease or lung disease, treatment focuses on the underlying condition and there is no convincing evidence that agents approved for pulmonary arterial hypertension are effective. For patients with chronic thromboembolic pulmonary hypertension, the treatment of choice is pulmonary endarterectomy. However, drugs intended specifically for the treatment of pulmonary arterial hypertension may be considered in inoperable cases or after suboptimal surgery.

Pulmonary hypertension with left-sided heart disease

Pulmonary hypertension (PH) with left-sided heart disease is defined, according to the latest Venice classification, as a Group 2 PH, which includes left-sided ventricular or atrial disease, and left-sided valvular diseases. These conditions are all associated with increased left ventricular filling pressure. Although PH with left-sided heart disease is a common entity, and long-term follow-up trials have provided firm recognition that development of left-sided PH carries a poor outcome, available data on incidence, pathophysiology, and therapy are sparse. Mitral stenosis was reported as the most frequent cause of PH several decades ago, but PH with left-sided heart disease is now usually caused by systemic hypertension and ischemic heart disease. In patients with these conditions, PH develops as a consequence of impaired left ventricular relaxation and distensibility. Chronic sustained elevation of cardiogenic blood pressure in pulmonary capillaries leads to a cascade of untoward retrograde anatomical and functional effects that represent specific targets for therapeutic intervention. The pathophysiological and clinical importance of the hemodynamic consequences of left-sided heart disease, starting with lung capillary injury and leading to right ventricular overload and failure, are discussed in this Review, focusing on PH as an evolving contributor to heart failure that may be amenable to novel interventions.

Heart failure in the elderly: advances and challenges

The elderly population (age > or =65 years) is increasing, and with it the prevalence of heart failure and associated morbidity, hospitalizations and costs. Despite advances, clinical trial data on heart failure therapy exclusively for elderly patients are lacking. However, trials of therapy for heart failure with left ventricular systolic dysfunction or low ejection fraction in primarily non-elderly patients showed mortality benefit in elderly patients. By contrast, trials for heart failure with normal left ventricular systolic function or preserved ejection fraction have not shown mortality benefit in elderly or non-elderly patients. Heart failure pharmacotherapy in the elderly is challenging; it needs to be individualized and consider aging-specific changes in physiology, drug metabolism, drug pharmacokinetics and tolerance, comorbidities, polypharmacy and drug-drug interactions that can contribute to adverse effects. More research into the biology of aging and clinical trials in elderly patients may lead to the discovery of new therapies for heart failure in the elderly.

Heart failure and pulmonary hypertension

When pulmonary hypertension (PH) and right ventricular dysfunction accompany heart failure, the impact on functional capacity and prognosis are ominous. Newer clinical strategies to preferentially lower pulmonary pressures and pulmonary vascular tone improve functional performance and symptoms of heart failure by targeting the nitric oxide signal transduction pathways, as with PDE5 inhibition. Additional studies are needed to determine if these therapies will impact long-term patient outcomes and elucidate the specific mechanisms whereby these treatments are effective. Furthermore, the recent finding that mutations in BMPR2 cause familial forms of pulmonary arterial hypertension and that BMPR2 expression is decreased in secondary forms of PH strongly implicate BMP signaling in the underlying pathophysiology of PH. Translation of emerging basic science insights in the vascular biology of PH and BMP signaling will provide novel therapeutic strategies for the spectrum of pulmonary hypertensive diseases.

The right heart and pulmonary circulation (III). The pulmonary circulation in heart failure

Pulmonary hypertension due to left heart disease is a pathophysiological and hemodynamic state which is present in a wide range of clinical conditions that affect left heart structures. Although the pulmonary circulation has traditionally received little attention, it is reasonable to say that today it is a fundamental part of cardiological evaluation. In patients with heart failure, the most important clinical factors are the presence of pulmonary hypertension and right ventricular function. These factors are also essential for determining prognosis and must be taken into account when making some of the most important therapeutic decisions. The pathophysiological process starts passively but later transforms into a reactive process. This latter process, in turn, has one component that can be reversed with vasodilators and another component that is fixed, in which the underlying mechanism is congestive vasculopathy (i.e. essentially medial hypertrophy and pulmonary arterial intimal fibrosis). Currently no specific therapy is available for this type of pulmonary hypertension and treatment is the same as for heart failure itself. The drugs that have been shown to be effective in pulmonary arterial hypertension have generally had a neutral effect in clinical trials. Nevertheless, we are involved in the clinical development of a number of groups of pharmacological compounds that will enable us to make progress in the near future.