Initial experience with bosentan therapy in patients considered ineligible for heart transplantation because of severe pulmonary hypertension

Heart Transplantation in a 14-Year-Old Boy in the Presence of Severe Out-of-Proportion Pulmonary Hypertension due to Restrictive Left Heart Disease: A Case Report

A 14-year-old boy after balloon valvuloplasty of severe aortic valve stenosis in the neonatal period was referred for heart-lung transplantation because of high grade pulmonary hypertension and left heart dysfunction due to endocardial fibroelastosis with severe mitral insufficiency. After heart catheterization, hemodynamic parameters were invasively monitored: a course of levosimendan and initiation of diuretics led to a decrease of pulmonary capillary wedge pressure (from maximum 35 to 24 mmHg). Instead of an expected decrease, mean pulmonary artery pressures (mPAP) increased up to 80 mmHg with increasing transpulmonary pressure gradient (TPG) up to 55 mmHg. Oral bosentan and intravenous epoprostenol then led to a ~50% decrease of mPAP (TPG between 16 and 22 mmHg). The boy was listed solely for heart transplantation which was successfully accomplished 1 month later.

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.

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.

Current pathophysiological concepts and management of pulmonary hypertension

Pulmonary hypertension (PH), increasingly recognized as a major health burden, remains underdiagnosed due mainly to the unspecific symptoms. Pulmonary arterial hypertension (PAH) has been extensively investigated. Pathophysiological knowledge derives mostly from experimental models. Paradoxically, common non-PAH PH forms remain largely unexplored. Drugs targeting lung vascular tonus became available during the last two decades, notwithstanding the disease progresses in many patients. The aim of this review is to summarize recent advances in epidemiology, pathophysiology and management with particular focus on associated myocardial and systemic compromise and experimental therapeutic possibilities. PAH, currently viewed as a panvasculopathy, is due to a crosstalk between endothelial and smooth muscle cells, inflammatory activation and altered subcellular pathways. Cardiac cachexia and right ventricular compromise are fundamental determinants of PH prognosis. Combined vasodilator therapy is already mainstay for refractory cases, but drugs directed at these new pathophysiological pathways may constitute a significant advance.

[Heart failure and heart transplant]

The mission of the Heart Failure and Transplantation Section of the Spanish Society of Cardiology is to study, to promote interest in, and to disseminate information about all aspects of myocardial dysfunction and heart transplantation. Heart failure is a highly prevalent condition that consumes a substantial proportion of healthcare resources. Consequently, there is considerable interest in the disorder. Numerous lines of clinical and preclinical research are actively being pursued and new ways of increasing knowledge about the disease are constantly being explored. The aim of this article was to describe the most recent developments concerning heart failure and its treatment. Firstly, the latest publications on chronic heart failure are analyzed. Then, there is a review of the most recent studies on resynchronization therapy and of clinical trials on acute heart failure. Thirdly, new developments in right heart dysfunction and pulmonary hypertension, and the findings of the Spanish Pulmonary Hypertension Registry are discussed. Finally, the latest information on ventricular assist devices and heart transplantation is presented. In addition, the most important data obtained from official transplantation registries (i.e. the Spanish Heart Transplantation Registry and the Spanish Post-Heart Transplantation Tumor Registry) are reviewed.

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.

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.

Bosentan

IMPORTANCE TO THE FIELD

Pulmonary arterial hypertension (PAH) is a morbid condition with high mortality if left untreated. Bosentan is an effective treatment option for group 1 pulmonary arterial hypertension. Bosentan improves exercise tolerance and functional class and delays the time to clinical worsening in these patients. Investigation is ongoing to determine its efficacy in other groups of pulmonary hypertension.

AREAS COVERED IN THIS REVIEW

This review provides a background on endothelin activity in PAH, as a rationale for the use of bosentan in this disease. It also presents evidence from key clinical trials of bosentan and discusses future directions in the study of bosentan to help the clinician better understand the role of bosentan in PAH management.

WHAT THE READER WILL GAIN

i) An understanding of the rationale for using endothelin receptor antagonists in treating PAH; ii) an understanding of the clinical evidence to support bosentan for the treatment of PAH; and iii) an understanding of how to use bosentan optimally in the treatment of PAH.

TAKE HOME MESSAGE

Bosentan is an effective and safe treatment for patients with PAH. Patients with suspected PAH should be evaluated carefully as the use of bosentan in non-group 1 pulmonary hypertension is still being investigated. Patients on bosentan should be monitored with monthly liver transaminase testing. Coadministration with other drugs should be reviewed carefully as drug-drug interactions may be important.

Pulmonary hypertension in heart failure

BACKGROUND

Pulmonary hypertension occurs in 60% to 80% of patients with heart failure and is associated with high morbidity and mortality.

METHODS AND RESULTS

Pulmonary artery pressure correlates with increased left ventricular end-diastolic pressure. Therefore, pulmonary hypertension is a common feature of heart failure with preserved as well as reduced systolic function. Pulmonary hypertension is partially reversible with normalization of cardiac filling pressures. Pulmonary vasculature remodeling and vasoconstriction create a second component, which does not reverse immediately, but has been shown to improve with vasoactive drugs and especially with left ventricular assist devices.

CONCLUSION

Many drugs used for idiopathic pulmonary arterial hypertension are being considered as treatment options for heart failure-related pulmonary hypertension. This is of particular significance in the heart transplant population. Randomized clinical trials with interventions targeting heart failure patients with elevated pulmonary artery pressure would be justified.

Initial Experience with Sildenafil, Bosentan, and Nitric Oxide for Pediatric Cardiomyopathy Patients with Elevated Pulmonary Vascular Resistance before and after Orthotopic Heart Transplantation

Background. Although pulmonary hypertension complicating dilated cardiomyopathy has been shown to be a significant risk factor for graft failure after heart transplantation, the upper limits of pulmonary vascular resistance (PVR) that would contraindicate pediatric heart transplantation are not known. Methods. A retrospective review of all pediatric orthotopic heart transplant (OHT) performed at our institution from 2002 to 2007 was performed. Seven patients with PVR > 6 Wood's units (WU) prior to transplant were compared pre- and postoperatively with 20 matched controls with PVR < 6 WU. All pulmonary vasodilator therapies used are described as well as outcomes during the first year posttransplant. Results. The mean PVR prior to transplantation in the 7 study cases was 11.0 ± 4.6 (range 6–22) WU, compared to mean PVR of 3.07 ± 0.9 WU (0.56–4.5) in the controls (P = .27 × 10⁻⁶). All patients with elevated PVR were treated pre-OHT with either Sildenafil or Bosentan. Post-OHT, case patients received a combination of sildenafil, iloprost, and inhaled nitric oxide. All 7 case patients survived one year post-OHT, and there was no statistical difference between cases and controls for hospital stay, rejection/readmissions, or graft right ventricular failure. Mean PVR in the cases at one and three months post-OHT was not significantly different between the two groups. Only one of the cases required prolonged treatment with iloprost after OHT. Conclusions. A PVR above 6 WU should not be an absolute contraindication to heart transplantation in children.

Current treatment options for early management in acute decompensated heart failure

Acute decompensated heart failure (ADHF) is a common syndrome that precedes over 100,000 hospitalizations in Canada per year (with length of stay in excess of six to eight days), making this the most costly disorder for patients older than 65 years of age. Over 85% of ADHF patients present with shortness of breath and exhibit evidence of volume overload. These findings may be variable in elderly patients, which complicates diagnosis. In fact, even in experienced centres, diagnostic accuracy is less than 80%. Despite advances in the treatment of chronic heart failure, meaningful improvements in outcomes associated with ADHF are very few. The basic assessment and treatments have not changed (early parenteral diuretics, electrocardiographic and oxygen saturation monitoring, supplemental oxygen administration). The introduction of measurement of natriuretic peptides in those in whom the diagnosis is uncertain may reduced the error rate by over 50%. The use of vasodilator therapy in the absence of cardiogenic shock can lead to earlier amelioration of symptoms, especially in those who do not respond to initial diuretics. Repeated monitoring of vital signs, body weight, electrolytes and creatinine levels is essential to minimize the risk of side effects of treatments. Noninvasive ventilation may reduce the need for endotracheal intubation in patients with severe ADHF and hypoxia at rest. Once the initial phase of heart failure treatment is completed, then the clinician should begin to focus on maximization of chronic heart failure therapy and discharge planning.

Indications for Heart Transplantation in Pediatric Heart Disease

Background— Since the initial utilization of heart transplantation as therapy for end-stage pediatric heart disease, improvements have occurred in outcomes with heart transplantation and surgical therapies for congenital heart disease along with the application of medical therapies to pediatric heart failure that have improved outcomes in adults. These events justify a reevaluation of the indications for heart transplantation in congenital heart disease and other causes of pediatric heart failure.

Methods and Results— A working group was commissioned to review accumulated experience with pediatric heart transplantation and its use in patients with unrepaired and/or previously repaired or palliated congenital heart disease (children and adults), in patients with pediatric cardiomyopathies, and in pediatric patients with prior heart transplantation. Evidence-based guidelines for the indications for heart transplantation or retransplantation for these conditions were developed.

Conclusions— This evaluation has led to the development and refinement of indications for heart transplantation for patients with congenital heart disease and pediatric cardiomyopathies in addition to indications for pediatric heart retransplantation.