Effect of the oral endothelin antagonist bosentan on the clinical, exercise, and haemodynamic status of patients with pulmonary arterial hypertension related to congenital heart disease

No Placebo Effect beyond Regression to the Mean on the Six Minute Walk Test in Pulmonary Arterial Hypertension Trials

In drug studies, patients are often included when the disease activity is high. This will make any treatment appear to lessen disease activity, although the improvement is biased by selection. This effect is known as regression towards the mean (RTM). We aimed at investigating drug trials in Pulmonary Arterial Hypertension (PAH) using the 6-minute walking distance test (6MWD) as a primary outcome for the phenomenon of RTM. An existing registry of 43 open label studies and 23 randomized controlled trials conducted between 1990 and 2009 was used as the data source. Data analysis was carried out for 18 randomized controlled trials (RCTs) and 24 open label studies out of this registry. Data were analyzed for verum and placebo arms of the RCTs separately, as well as for the open label arms. In the verum arms, the overall effect given as 33.2 m (95% CI: 25.7; 40.6]); 6MWD was slightly lower than the effect in the observational studies, with 44.6 m (95% CI: [25.4; 63.8]). After studying and interpreting the data, we found that regression towards the mean plays only a minor role in PAH studies. In particular, placebo effects in the RCTs were negligibly small, with a mean 6MWD of -2.5 m (95% CI: [-9.8; 4.7]) in the placebo arm. Therefore, our analysis indicates that results of non-randomized observational studies can be regarded as valid tools for gaining valid clinical effects in patients with PAH.

Targeted Therapies in Patients with Pulmonary Arterial Hypertension Due to Congenital Heart Disease

Pulmonary arterial hypertension (PAH) is a devastating cardiovascular disease leading to right heart failure and death if untreated. Medical therapies for PAH have evolved substantially over the last decades and are associated with improvements in functional class, quality of life, and survival. PAH-targeted therapies now consist of multiple inhaled, oral, subcutaneous, and intravenous therapies targeting the phosphodiesterase, guanylate cyclase, endothelin and prostacyclin pathways. Patients with congenital heart disease (CHD) are at high risk of developing PAH and growing evidence exists that PAH-targeted therapy can be beneficial in PAH-CHD. However, the PAH-CHD patient population is challenging to treat due to the heterogeneity and complexity of their cardiac lesions and associated comorbidities. Furthermore, most high-quality randomized placebo-controlled trials investigating the effects of PAH-targeted therapies only included a minority of PAH-CHD patients. Few randomized, controlled trials have investigated the effects of PAH-targeted therapy in pre-specified PAH-CHD populations. Consequently, the results of these clinical trials cannot be extrapolated broadly to the PAH-CHD population. This review summarizes the data from high-quality clinical PAH treatment trials with a specific focus on the PAH-CHD population.

Evidence base for specific pulmonary vasodilators in adults with congenital heart disease

After reviewing the current definitions and classification of pulmonary hypertension (PH) associated with congenital heart disease (CHD), based on an analysis of 59 clinical trials (of which 14 are randomized controlled trials) drugs registered in the Russian Federation, the evidence base for PH therapy in adults with CHD is provided. The presence of a randomized controlled trial of bosentan BREATHE-5 and uncontrolled trials of other drugs became the basis for a higher class and level of evidence of bosentan (IB) compared to other drugs (IIaC) for Eisenmenger syndrome in the current European (ERS/ESC 2015) and updated Russian (2020) guidelines. According to the updated European (ESC 2020) guidelines for congenital heart disease in adults, in Eisenmenger patients with reduced exercise capacity (6MWT distance 450 m), a treatment strategy with initial endothelin receptor antagonist monotherapy should be considered followed by combination therapy if patients fail to improve (IIaB), in low- and intermediate-risk patients with repaired simple lesions and pre-capillary PH, initial oral combination therapy or sequential combination therapy is recommended and high-risk patients should be treated with initial combination therapy including parenteral prostanoids (IA) and endothelin receptor antagonists and phosphodiesterase 5 inhibitors may be considered in selected patients with elevated pulmonary pressure/resistance in the absence of elevated ventricular end diastolic pressure (IIbC). Only three (bosentan, macitentan and selexipag) out of seven specific pulmonary vasodilators registered in the Russian Federation have indications for pulmonary arterial hypertension associated with congenital heart disease and Eisenmenger syndrome or pulmonary arterial hypertension associated with corrected simple congenital heart disease in the instructions for use.

Preventing disease progression in Eisenmenger syndrome

Introduction: Eisenmenger syndrome describes a condition in which a congenital heart defect has caused severe pulmonary vascular disease, resulting in reversed (right-left) or bidirectional shunting and chronic cyanosis.Areas covered: In this paper, the progression of congenital heart defects to Eisenmenger syndrome, including early screening, diagnosis and operability are covered. The mechanisms of disease progression in Eisenmenger syndrome and management strategies to combat this, including the role of pulmonary arterial hypertension therapies, are also discussed.Expert opinion/commentary: Patients with congenital heart disease (CHD) are at increased risk of developing pulmonary arterial hypertension with Eisenmenger syndrome being its extreme manifestation. All CHD patients should be regularly assessed for pulmonary hypertension. Once Eisenmenger syndrome develops, shunt closure should be avoided. The clinical manifestations of Eisenmenger syndrome are driven by the systemic effects of the pulmonary hypertension, congenital defect and long-standing cyanosis. Expert care is essential for avoiding pitfalls and preventing disease progression in this severe chronic condition, which is associated with significant morbidity and mortality. Pulmonary arterial hypertension therapies have been used alongside supportive care to improve the quality of life, exercise tolerance and the outcome of these patients, although the optimal timing for their introduction and escalation remains uncertain.

Evolving Paradigms in the Treatment of Atrial Septal Defects With Pulmonary Arterial Hypertension

Atrial septal defects are one of the most frequently diagnosed congenital heart defects in adulthood. The presence of concurrent moderate or severe pulmonary arterial hypertension without Eisenmenger syndrome at the time of diagnosis can make for a challenging clinical scenario. There is continually evolving literature to determine the ideal approach to this subset of patients. Here we aim to review the clinical presentation, history, medical therapy, and closure options for atrial septal defects-pulmonary arterial hypertension with predominant left-to-right shunting, in the absence of Eisenmenger syndrome.

The Effect of Endothelin Receptor Antagonists in Patients with Eisenmenger Syndrome: A Systematic Review

INTRODUCTION

The efficacy of endothelin receptor antagonists (ERAs) in the management of Eisenmenger syndrome (ES) remains controversial. The aim of this study is to systemically review the safety and effects of ERAs in improving the quality of life and basic cardiac functions of these patients.

METHODS

Twelve databases were searched, including PubMed, Web of Science, Scopus, Virtual Health Library, World Health Organization (WHO) Global Health Library, Google Scholar, POPLINE, Systems for Information of Grey Literature in Europe, New York Academy of Medicine, ClinicalTrials.gov, metaRegister of Controlled Trials and the WHO International Clinical Trials Registry Platform, through August 2016. We included randomized clinical trials addressing the effect of ERAs on cardiac functions in patients with ES. The quality of studies was assessed using the Cochrane Collaboration tool.

RESULTS

We included two trials represented by four papers, of which three papers reported the efficacy of bosentan against placebo and one paper reported the results of a combination of bosentan and sildenafil versus placebo and bosentan. One trial showed a significant effect of bosentan treatment over placebo on indexed pulmonary vascular resistance and mean pulmonary artery pressure, but a non-significant increase in 6-min walk distance and a non-significant effect on systemic pulse oximetry. The other trial reported the safe but non-significant effect of combination therapy of bosentan and sildenafil compared with bosentan and placebo.

CONCLUSIONS

This study demonstrated safety and improved hemodynamic effects of bosentan in ES, with a controversial effect on exercise capacity. Further randomized controlled trials with longer follow-up duration are needed to confirm these results.

The efficiency of endothelin receptor antagonist bosentan for pulmonary arterial hypertension associated with congenital heart disease: A systematic review and meta-analysis

BACKGROUND

Oral bosentan has been widely applied in pulmonary arterial hypertension associated with congenital heart disease (PAH-CHD). A systemic review and meta-analysis was conducted for a therapeutic evaluation of oral bosentan in both adult and pediatric patients with PAH-CHD. The acute responses and a long-term effect were respectively assessed in a comparison with baseline characteristics, and the improvement of exercise tolerance was analyzed.

METHODS

PubMed, Medline, Embase, and Cochrane Central Register of clinical controlled trails or observational studies have been searched for a recording of bosentan effects on the PAH-CHD participants. For mortality and rate of adverse events (AEs), it was described in detail. Randomized-effects model or fixed-effects model was used to calculate different effective values with a sensitivity analysis.

RESULTS

Seventeen studies were pooled in this review, and 3 studies enrolled the pediatric patients. Among all studies, 456 patients were diagnosed with PAH-CHD, and 91.7% were treated with oral bosentan. With a term less than 6 months of bosentan therapy, there existed a significant improvement in 6-minute walk distance (6MWD) and the World Health Organization functional class (WHO-FC), but no such differences in Borg dyspnea index scores (BDIs) and the resting oxygen saturation (SpO2). Although with a prolonged treatment, not only 6MWD and FC, but also the resting SpO2 and heart rate were changed for a better exercise capability. Additionally, compared with the basic cardiopulmonary hemodynamics, it showed a statistically significant difference in mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance index (PVRi). Although a limitation of pooled studies with comparative outcomes of different terms, outcomes presented a lower WHO-FC which contributes to a success in a prolonged treatment.

CONCLUSIONS

Bosentan in PAH-CHD is well established and still requires clinical trials for an identification of its efficiency on CHD patients for an optimized period lessening a serious complication and the common AEs.

How to Treat a Patient with Thromboangiitis Obliterans: A Systematic Review

To date, there is still no treatment protocol for patients with thromboangiitis obliterans (TAO) who are also afflicted with critical limb ischemia (CLI). Smoking cessation on its own cannot be considered a treatment for the purposes of salvaging a limb of a TAO patient with CLI. The aim of this review was to evaluate different studies of various treatment protocols for avoiding amputation in TAO patients. A systematic search for relevant studies dating from 1990 to the end of 2016 was performed on the PubMed, SCOPUS, and Science Direct databases. Only 24 studies fulfilled the inclusion criteria, of which only one was a randomized controlled trial (RCT). The remaining studies were quasi-experimental with various treatments and follow-up durations. Therefore, meta-analysis was not performed. Judging from the major amputation rates after the suggested treatments were performed, no treatment was particularly effective. This review demonstrated that more standard RCTs are needed to resolve this treatment issue involved in TAO. In addition, because health insurance coverage for TAO patients differs by country, regional cost-benefit and cost-efficacy studies of the suggested treatments for TAO are highly recommended.

Advanced therapies for the management of adults with pulmonary arterial hypertension due to congenital heart disease: a systematic review

Pulmonary arterial hypertension (PAH) secondary to congenital heart disease (CHD) is the third most common cause of PAH, and it is becoming increasingly common as improvements in the management of CHD have led to increased life expectancy for these patients. The medical management of PAH due to CHD (PAH-CHD) is largely the same as what has been used for the treatment of idiopathic PAH, though the body of literature supporting this management decision is very small. There are currently few studies available which specifically focus on the treatment of PAH-CHD. The purpose of this literature review is to compare the results of those studies that assessed the response to medical therapy among adults with PAH-CHD; studies were excluded if they focused on paediatric patients, did not include an assessment of 6 min walking distance or specifically assessed combination therapies. This review found that riociguat, bosentan, epoprostenol and sildenafil were all capable of improving functional capacity and haemodynamic parameters in patients with PAH-CHD, but whether this corresponds to an increase in mortality remains to be seen. Limitations of this review include the small sample size and variable duration of the included studies, which makes drawing direct comparisons between studies and the study drugs difficult. The lack of large, randomised double-blind clinical trials comparing different drugs head to head highlights an area that is ripe for ongoing medical research, the results of which may help shape future treatment algorithms tailored specifically for adults with PAH-CHD.

Advanced Therapy in Eisenmenger Syndrome: A Systematic Review

Treatment options for patients with the Eisenmenger syndrome have until recently been scarce, but new knowledge in the field of pulmonary arterial hypertension has expanded the therapeutic possibilities for these patients. Advanced therapy with pulmonary vasodilators has become part of the standard treatment, offering long-term benefits on exercise capacity, clinical symptoms, and possibly survival. However, there are currently only few studies to guide the use of advanced therapies in this population, and important questions such as indications for initiation or escalation of advanced therapy and valid effect parameters and treatment goals remain unanswered. This review covers the pharmacology, therapeutic options, risk stratification, and treatment strategy of pulmonary arterial hypertension-specific drugs in patients with Eisenmenger syndrome.

Pharmacokinetics of drugs for pediatric pulmonary hypertension

BACKGROUND

Over the past few years, several drugs, each with a different mechanism, have been developed for the treatment of pulmonary hypertension (PH) and are now prescribed in the clinical setting. While the optimal doses of these drugs in adults have been determined, the optimal dose in children, however, is unclear. The aim of this study was therefore, to measure blood drug levels and analyze the pharmacokinetics of two such drugs in children.

METHODS

From April 2010 to May 2015, we prospectively enrolled 23 children with PH for treatment with bosentan and/or tadalafil. Twenty children were treated with bosentan and 19 received tadalafil. Sixteen children were given both drugs. Blood samples were collected after 2 weeks of treatment, and blood drug levels measured using high-performance liquid chromatography.

RESULTS

For both drugs, the peak plasma concentration was lower and the half-life was shorter than the known values in adults. The blood trough level of bosentan significantly correlated with its dose, but no such correlation was seen for tadalafil. For both drugs, no correlation was observed between age and blood drug levels.

CONCLUSIONS

Oral dosing with bosentan and tadalafil in children may not achieve therapeutic blood concentration. Thus, the optimal dosing must be established individually while monitoring blood drug level.

Perioperative pharmacological management of pulmonary hypertensive crisis during congenital heart surgery

Pulmonary hypertensive crisis is an important cause of morbidity and mortality in patients with pulmonary arterial hypertension secondary to congenital heart disease (PAH-CHD) who require cardiac surgery. At present, prevention and management of perioperative pulmonary hypertensive crisis is aimed at optimizing cardiopulmonary interactions by targeting prostacyclin, endothelin, and nitric oxide signaling pathways within the pulmonary circulation with various pharmacological agents. This review is aimed at familiarizing the practitioner with the current pharmacological treatment for dealing with perioperative pulmonary hypertensive crisis in PAH-CHD patients. Given the life-threatening complications associated with pulmonary hypertensive crisis, proper perioperative planning can help anticipate cardiopulmonary complications and optimize surgical outcomes in this patient population.

Assessment of operability of patients with pulmonary arterial hypertension associated with congenital heart disease

Pulmonary arterial hypertension (PAH) is a common complication of congenital heart disease, and is now predominantly among patients with uncorrected left-to-right shunts. A growing population is characterized by persistent or recurrent PAH after surgical or interventional correction of left-to-right shunts; the latter having a worse prognosis than other forms of PAH associated with congenital heart disease. New treatments for PAH have been shown to be effective in improving PAH exercise capacity and hemodynamics, raising the hope for making previously inoperable congenital heart defects operable and shifting the framework for the assessment of operability. This review focuses on current methods for assessing operability in PAH associated with congenital heart disease, and the possibility of "treat-and-repair" vs. "repair-and-treat" strategies for patients with inoperable or borderline PAH.

Impact of pulmonary vascular resistances in heart transplantation for congenital heart disease

Congenital heart disease is one of the major diagnoses in pediatric heart transplantation recipients of all age groups. Assessment of pulmonary vascular resistance in these patients prior to transplantation is crucial to determine their candidacy, however, it is frequently inaccurate because of their abnormal anatomy and physiology. This problem places them at significant risk for pulmonary hypertension and right ventricular failure post transplantation. The pathophysiology of pulmonary vascular disease in children with congenital heart disease depends on their pulmonary blood flow patterns, systemic ventricle function, as well as semilunar valves and atrioventricular valves structure and function. In our review we analyze the pathophysiology of pulmonary vascular disease in children with congenital heart disease and end-stage heart failure, and outline the state of the art pre-transplantation medical and surgical management to achieve reverse remodeling of the pulmonary vasculature by using pulmonary vasodilators and mechanical circulatory support.

Congenital heart disease and pulmonary hypertension

Many patients with congenital heart disease and systemic-to-pulmonary shunts develop pulmonary arterial hypertension (PAH), particularly if the cardiac defect is left unrepaired. A persistent increase in pulmonary blood flow may lead to obstructive arteriopathy and increased pulmonary vascular resistance, a condition that can lead to reversal of shunt and cyanosis (Eisenmenger syndrome). Cardiac catheterization is crucial to confirm diagnosis and facilitate treatment. Bosentan is the only medication to date to be compared with placebo in a randomized controlled trial specifically targeting congenital heart disease-associated PAH. Lung transplantation with repair of the cardiac defect or combined heart-lung transplantation is reserved for recalcitrant cases.

Changes in exercise capacity and cardiac performance in a series of patients with Eisenmenger's syndrome transitioned from selective to dual endothelin receptor antagonist

BACKGROUND

Differences in clinical effects between selective and dual endothelin (ET) receptor antagonists (ERA) in patients with pulmonary arterial hypertension (PAH) are currently unknown. We aimed to assess prospectively how transition from selective (sitaxsentan) to dual (bosentan) ERA affected exercise capacity and cardiocirculatory performance in patients with Eisenmenger's syndrome.

METHODS

A series of seven stable patients with Eisenmenger's syndrome aged 40.0 (30.0-56.0) years old treated with sitaxsentan were assessed before and three months after transition to bosentan. Six minute walk test and magnetic resonance to assess LV and RV mass, volume and ejection fraction, and pulmonary flow, and laboratory tests were performed.

RESULTS

We observed an increase in LV mass [96.5 (66.0-116.0) vs. 123.0 (93.0-146.0)g; p=0.03], LV ejection fraction [55.0 (44.0-63.0) vs. 65.0 (58.0-70.0)%; p=0.02)], and pulmonary flow [64 (53.0-71.0) vs. 69.0 (55.0-84.0)ml/beat; p=0.046]. This was accompanied by an increase of oxygen saturation, elongation of 6MWD [435.0 (378.0-482.3) vs. 474 (405.0-534.7); p=0.02], decrease of NTproBNP level and increase of ET-1 level.

CONCLUSIONS

Three month follow-up of stable patients with Eisenmenger's syndrome transitioned from sitaxsentan to bosentan revealed improvement of exercise capacity despite significant elevation of ET-1 level. Concurrent increase of LV ejection fraction and pulmonary flow might have contributed to these favourable effects.

Adult congenital heart disease and pulmonary arterial hypertension: the Texas Adult Congenital Heart Program experience

Congenital heart disease (CHD) is a common structural defect of the heart or major blood vessels. Patients with adult congenital heart disease (ACHD) have medical needs that are distinct from those of pediatric patients with CHD, and the transition into adult health care is important for management of the patient with ACHD. A large proportion of patients with CHD develop diseases and complications associated with the long-term stress of intracardiac shunts. Pulmonary arterial hypertension (PAH) is a significant complication of some CHD lesions. The treatment of these patients remains challenging due to their combined heart and lung disease, and multidisciplinary care is ofen necessitated for a variety of secondary conditions. A number of treatment options are available for the management of PAH associated with CHD, including prostanoids, phosphodiesterase type-5 inhibitors, and endothelin receptor antagonists. This article discusses the diagnosis and management of such ACHD patients with PAH.

Clinical efficacy of phosphodiesterase-5 inhibitor tadalafil in Eisenmenger syndrome--a randomized, placebo-controlled, double-blind crossover study

OBJECTIVES

In a randomized double-blind crossover trial, we compared the efficacy of phosphodiesterase-5 (PDE-5) inhibitor tadalafil with placebo in patients of Eisenmenger Syndrome (ES). The primary end point was the change in 6-minute walk test distance (6 MWD). Secondary end points were the effect of the drug on systemic oxygen saturation (SO(2) ), pulmonary vascular resistance (PVR), systemic vascular resistance (SVR), effective pulmonary blood flow (EPBF), and World Health Organization (WHO) functional class.

BACKGROUND

ES is a disorder with limited treatment options. Uncontrolled studies have shown PDE-5 inhibitors to be beneficial in patients of ES.

METHODS

Twenty-eight symptomatic adult patients of ES with weight ≥30 kg in WHO class II and III were enrolled. Patients were given 40 mg of tadalafil or matching placebo for 6 weeks followed by crossover to the other drug after a washout period of 2 weeks. Assessment of WHO class, exercise capacity by 6 MWD, and various hemodynamic parameters by cardiac catheterization was done at baseline, after 6 weeks and at the end of the study.

RESULTS

All patients completed the study. There was significant increase in 6 MWD following drug administration compared with baseline (404.18 ± 69.54 m vs. 357.75 ± 73.25 m, P < .001). Compared with placebo, tadalafil produced significant decrease in PVR (-7.32 ± 1.58, P < .001), resulting in significant increase in EPBF (0.12 ± 0.05, P= .03), SO(2) % (1.72 ± 0.58, P= .007), and WHO functional class (1.96 ± 0.18 vs. 2.14 ± 0.44, P= .025), with no significant change in SVR (P= NS).

CONCLUSION

In this first short-term placebo-controlled trial of tadalafil in patients of ES, the drug was well tolerated and significantly improved exercise capacity, functional class, SO(2) , and pulmonary hemodynamics.

The Adult Patient with Eisenmenger Syndrome: A Medical Update after Dana Point Part II: Medical Treatment - Study Results

Eisenmenger syndrome is the most severe form of pulmonary arterial hypertension and arises on the basis of congenital heart disease with a systemic-to-pulmonary shunt. Due to the chronic slow progressive hypoxemia with central cyanosis, adult patients with the Eisenmenger syndrome suffer from a complex and multisystemic disorder including coagulation disorders (bleeding complications and paradoxical embolisms), renal dysfunction, hypertrophic osteoarthropathy, heart failure, reduced quality of life and premature death.

For a long time, therapy has been limited to symptomatic options or lung or combined heart-lung transplantation. As new selective pulmonary vasodilators have become available and proven to be beneficial in various forms of pulmonary arterial hypertension, this targeted medical treatment has been expected to show promising effects with a delay of deterioration also in Eisenmenger patients. Unfortunately, data in Eisenmenger patients suffer from small patient numbers and a lack of randomized controlled studies.

To optimize the quality of life and the outcome, referral of Eisenmenger patients to spezialized centers is required. In such centers, specific interdisciplinary management strategies of physicians specialized on congenital heart diseases and PAH should be warranted.

This medical update emphasizes the current diagnostic and therapeutic options for Eisenmenger patients with particularly focussing on the medical treatment and corresponding study results.

Bosentan in pulmonary arterial hypertension: a comparison between congenital heart disease and chronic pulmonary embolism

Background. In patients with pulmonary hypertension, it is unknown whether the treatment effect of bosentan is dependent on the duration of pulmonary vessel changes. Therefore, we studied the response to bosentan in patients with life-long pulmonary vessel changes (pulmonary arterial hypertension (PAH) due to congenital heart disease (CHD)) and in patients with subacutely induced pulmonary vessel changes (chronic thromboembolic pulmonary hypertension (CTEPH)).Methods. In this open-label study, 18 patients with PAH due to CHD and 16 patients with CTEPH were treated with bosentan for at least one year. All patients were evaluated at baseline and during follow-up by means of the six-minute walk distance (6-MWD) and laboratory tests.Results. Improvement of 6-MWD was comparable in patients with PAH due to CHD (444+/-112 m to 471+/-100 m, p=0.02), and in CTEPH (376+/-152 m to 423+/-141 m, p=0.03) after three months of treatment. After this improvement, 6-MWD stabilised in both groups.Conclusion. Although duration of pulmonary vessel changes is strikingly different in patients with PAH due to CHD and CTEPH, the effect of one year of bosentan treatment was comparable. The main treatment effect appears to be disease stabilisation and decreasing the rate of deterioration. (Neth Heart J 2009;17:334-8.).

Do patients with complete transposition of the great arteries and severe pulmonary hypertension benefit from an arterial switch operation?

BACKGROUND

Whether an arterial switch operation benefits patients with transposition of the great arteries and severe pulmonary hypertension (PH) remains controversial. Therefore, we evaluated the relationship between preoperative PH and early and midterm clinical outcomes after an arterial switch procedure.

METHODS

In this retrospective study, 101 consecutive patients with transposition of the great arteries underwent an arterial switch operation between February 2004 and October 2007. Seventy had a ventricular septal defect as well; patients with intact ventricular septum and complicated concomitant abnormities were excluded. Preoperative medical records were reviewed and mean follow-up was 22.4±15.2 months. After sternotomy, we directly measured pulmonary artery pressure before and after instituting extracorporeal circulation. Patients were divided into three groups according to mean pulmonary artery pressure (mPAP): control group (mPAP<25 mm Hg, n=23), moderate PH group (mPAP 25 to 50 mm Hg, n=37), and severe PH group (mPAP≥50 mm Hg, n=10). Early and midterm results were compared among groups.

RESULTS

Postoperatively, pulmonary artery pressure of both the moderate and severe PH groups decreased significantly. There were no significant differences in occurrence of postoperative complications or in-hospital mortality in the three groups (control group, 8.7%; moderate PH group, 8.1%; severe PH group, 10%; p=0.98). However, midterm mortality differed significantly (control group, 4.3%; moderate PH group, 2.7%; severe PH group, 40%; p<0.01).

CONCLUSIONS

Patients with transposition of the great arteries and mPAP less than 50 mm Hg can achieve satisfying results after an arterial switch operation. However, even though the operation can decrease pulmonary artery pressure, patients with preoperative mPAP greater than 50 mm Hg still suffer from high midterm mortality.

Pulmonary arterial hypertension in adults with congenital heart disease

Pulmonary arterial hypertension (PAH) is a common problem in adult patients with congenital heart disease. We review available data on aetiology, clinical presentation, prognosis and management of PAH in this setting. In addition, we discuss general management strategies and emerging disease-targeting therapies.

Adult patients with pulmonary arterial hypertension due to congenital heart disease: a review on advanced medical treatment with bosentan

Pulmonary arterial hypertension (PAH) is a progressive disease with poor survival outcome. PAH is classified by the 2009 updated clinical classification of pulmonary hypertension and a major subgroup is PAH due to congenital heart disease (CHD) with systemic-to-pulmonary shunt. CHD-PAH is a result of systemic-to-pulmonary shunting and chronic increased flow that ultimately results in adaptations of pulmonary vasculature and endothelial dysfunction. The advanced stage is called Eisenmenger syndrome which forms a small percentage (1%) of all CHD patients. Therapies targeted on PAH symptoms are called primary therapy for PAH, but most CHD-PAH patients progress to advanced therapy which is directed at the PAH itself. In CHD-PAH, advanced therapies are extensively investigated for all three major pathways: endothelin-1 receptor antagonists such as bosentan, prostanoids such as epoprostenol and phosphodiesterase 5 inhibitors such as sildenafil. Endpoints in most trials were catheterization hemodynamics, World Health Organization functional class, six-minute walking distance and patient-focused outcomes, based on quality of life questionnaires and Borg dyspnea index. The BREATHE-5 and EARLY study were two important randomized controlled trials showing efficacy of bosentan at short follow-up. Moreover in patients with Eisenmenger syndrome, one recent survival retrospective study with majority of patients on bosentan showed strong survival benefit over conservative therapy. A diversity of prospective cohort and retrospective studies were performed but all with limited data, due to small numbers and heterogeneity of underlying CHD diagnoses. Further larger studies are needed to determine optimal treatment for adults with CHD-PAH. This review focuses on bosentan in CHD-PAH. In particular, we discuss outcome of various clinical trials and compare efficacy and safety of bosentan to other advanced therapies.

Exercise testing and prescription in patients with congenital heart disease

The present paper provides a review of the literature regarding exercise testing, exercise capacity, and the role of exercise training in patients with congenital heart disease (CHD). Different measures of exercise capacity are discussed, including both simple and more advanced exercise parameters. Different groups of patients, including shunt lesions, pulmonary valvar stenosis, patients after completion of Fontan circulation, and patients with pulmonary arterial hypertension are discussed separately in more detail. It has been underscored that an active lifestyle, taking exercise limitations and potential risks of exercise into account is of utmost importance. Increased exercise capacity in these patients is furthermore correlated with an improvement of objective and subjective quality of life.

Endothelin receptor antagonists are an effective long term treatment option in pulmonary arterial hypertension associated with congenital heart disease with or without trisomy 21

INTRODUCTION

Traditionally, treatment options for patients with pulmonary arterial hypertension associated with congenital heart disease (PAH-CHD) are limited. Bosentan has been shown to improve pulmonary haemodynamics and exercise tolerance short term but long term clinical studies are lacking.

AIM

To report long term efficacy and safety data with endothelin receptor antagonists (ERA) in patients with PAH associated CHD.

METHODS

Prospective, open label, uncontrolled, single centre study of 53 patients (33 females, 17 Trisomy 21, mean age 34 ± 12 years) prescribed ERA (48 bosentan, 5 sitaxentan) from 2003 to August 2009. Outcome measurements of oxygen saturation (SaO2), WHO functional class, 6-minute walk test distance (6MWD) and adverse events were analysed.

RESULTS

Mean duration of therapy was 15 ± 13 months in 53 patients with CHD. Four patients failed ERA, seven died (five progressive RHF) and one delisted from transplantation. No abnormal liver transaminases occurred on bosentan, with one case on sitaxentan. After 3, 6, 12, 18 and 24 months of treatment a significant improvement was seen in WHO functional class (mean 3.15 vs 2.8 vs 2.5 vs 2.5 vs 2.4 vs 2.4; p<0.01) and 6MWD (344 ± 18 vs 392 ± 17 vs 411 ± 17 vs 420 ± 17 vs 442 ± 18 vs 417 ± 23: p<0.0005, p<0.01) compared with baseline. The Trisomy 21 and PAH-CHD showed a significant improvement in 6MWD at 6 and 12 months (263 ± 24 vs 348 ± 29 vs 360 ± 32, p<0.01, p<0.05) respectively. No changes in SaO2, BNP, RV or LV function were demonstrated during follow-up.

CONCLUSION

This large single centre study demonstrates that endothelin receptor antagonism is an effective and safe treatment in PAH associated CHD with or without Trisomy 21. The improvements in exercise tolerance are similar to reported benefits in other forms of PAH.

Canadian Cardiovascular Society 2009 Consensus Conference on the management of adults with congenital heart disease: complex congenital cardiac lesions

With advances in pediatric cardiology and cardiac surgery, the population of adults with congenital heart disease (CHD) has increased. In the current era, there are more adults with CHD than children. This population has many unique issues and needs. They have distinctive forms of heart failure and their cardiac disease can be associated with pulmonary hypertension, thromboemboli, complex arrhythmias and sudden death. Medical aspects that need to be considered relate to the long-term and multisystemic effects of single ventricle physiology, cyanosis, systemic right ventricles, complex intracardiac baffles and failing subpulmonary right ventricles. Since the 2001 Canadian Cardiovascular Society Consensus Conference report on the management of adults with CHD, there have been significant advances in the field of adult CHD. Therefore, new clinical guidelines have been written by Canadian adult CHD physicians in collaboration with an international panel of experts in the field. Part III of the guidelines includes recommendations for the care of patients with complete transposition of the great arteries, congenitally corrected transposition of the great arteries, Fontan operations and single ventricles, Eisenmenger's syndrome, and cyanotic heart disease. Topics addressed include genetics, clinical outcomes, recommended diagnostic workup, surgical and interventional options, treatment of arrhythmias, assessment of pregnancy risk and follow-up requirements. The complete document consists of four manuscripts, which are published online in the present issue of The Canadian Journal of Cardiology. The complete document and references can also be found at www.ccs.ca or www.cachnet.org.

The role of calcium channel blockers, steroids, anticoagulation, antiplatelet drugs, and endothelin receptor antagonists

The rationale for the drug therapy of pulmonary artery hypertension is to reduce mortality and morbidity caused by failure of right ventricular adaptation to an elevated pulmonary vascular resistance. We review the evidence for the use of calcium-channel blockers, steroids, anticoagulation, antiplatelet drugs, and endothelin receptor antagonists in the management of pulmonary artery hypertension. The drugs we discuss are more suited to long-term outpatient therapy. These drugs have not found a routine place in intensive care management, and calcium-channel blockers are contraindicated in patients with right-heart failure. The efficacy of many agents has been extrapolated from data acquired in adult patients and applied to children. All of us involved in the care of young patients with pulmonary artery hypertension should advocate for both the inclusion of younger patients in clinical trials and the design of distinctly pediatric trials with pharmaceutical and drug administration agencies. It is only with data derived from pediatric inclusive studies that we shall be able to recommend therapy with strong evidence. However, it is important to point out that the use of newer agents for the treatment of chronic pulmonary artery hypertension (prostacyclin, endothelin receptor antagonists, nitric oxide, and sildenafil) have not been shown to improve survival unequivocally and have relied on surrogates, such as exercise capacity. There are no long-term studies of survival benefit. Recent studies have included data on time to clinical worsening, which may be a more predictive surrogate of survival.

Late-onset pulmonary arterial hypertension after a successful atrial or arterial switch procedure for transposition of the great arteries

Common complications after surgery for transposition of the great arteries (TGA) include systemic ventricular dysfunction and arrhythmia after atrial baffle repair (AB) and outflow tract stenosis or regurgitation after the arterial switch (AS). Severe pulmonary hypertension (PHT) is a rarely reported problem after AB and AS. In this study we sought to evaluate the frequency of late onset severe PHT following surgical repair for TGA. We report 3 cases, 2 after AB and 1 after AS, describe the frequency of this complication and treatment response, by comparing the response to pulmonary vasodilators in this group of patients to that of idiopathic or connective tissue disease (CTD) related PHT. We currently follow 85 patients >or=17 years of age with repaired TGA; 77 after AB and 8 after AS. 3.5% of our adult congenital heart disease patients with TGA have developed late severe PHT. None of these patients demonstrated clinical improvement with Bosentan at 6 months, however 2 of 3 were stabilised with the addition of Sildenafil to initial therapy. The third patient died 4 months after the diagnosis of severe PHT, whilst waiting for heart-lung transplantation, despite Bosentan, Sildenafil and inotropic support. By contrast, of 37 patients with idiopathic or CTD related PHT commenced on Bosentan as initial therapy, 32 (86.5%) demonstrated a clinical response at 6 months; the other patients had Sildenafil as added therapy after 6 months. Our data suggest that patients with TGA and late onset PHT are less likely to achieve a clinical response on pulmonary vasodilator monotherapy (P = 0.006). Whilst more investigation is needed, our experience suggests an aggressive clinical course, often requiring combination PHT treatment.

Endothelin receptor antagonist therapy in congenital heart disease with shunt-associated pulmonary arterial hypertension: a qualitative systematic review

BACKGROUND

Congenital heart disease (CHD) with systemic-topulmonary shunting is associated with pulmonary arterial hypertension (PAH). There are similar clinical and pathophysiological features between CHD with shunt-associated PAH and idiopathic PAH. Endothelin-receptor antagonists (ERAs) are oral medications that improve pulmonary hemodynamics, symptoms and functional capacity in many PAH patients. However, the role of ERAs in CHD with shunt-associated PAH is unclear.

METHODS

MEDLINE, EMBASE and the Cumulative Index of Nursing and Allied Health Literature (CINAHL) databases were searched for articles published from 1966 through September 2006, as well as bibliographies of all retrieved papers. All published English-language studies of adult CHD patients with shunt-associated PAH treated with ERAs were reviewed for clinical, functional and hemodynamic outcomes.

RESULTS

Ten studies of 174 adult CHD subjects with shunt-associated PAH were identified. Other than one placebo-controlled, randomized clinical trial, all studies were open-label, uncontrolled observational trials. Subjects were treated with the ERA bosentan for a mean (+/- SD) of 9+/-7 months. Nine studies reported improved World Health Organization (WHO) modification of the New York Heart Association functional class, with 95 of 164 subjects (58%) improving by at least one functional class. The 6 min walk distance improved in all eight studies in which it was assessed. Bosentan was generally well tolerated; 2.3% of subjects withdrew because of elevated liver enzymes. Two patients with WHO functional class IV PAH died during bosentan therapy.

CONCLUSION

Treatment of CHD patients with shunt-associated PAH with the ERA bosentan is associated with an improvement in functional class and objectively measured exercise capacity. The consistency of the uncontrolled data and the positive results of a single randomized clinical trial suggest a role for ERA therapy in CHD patients with shunt-associated PAH. Caution is suggested when considering bosentan therapy for CHD patients with WHO functional class IV PAH.

Regression toward the mean--a detection method for unknown population mean based on Mee and Chua's algorithm

Background

Regression to the mean (RTM) occurs in situations of repeated measurements when extreme values are followed by measurements in the same subjects that are closer to the mean of the basic population. In uncontrolled studies such changes are likely to be interpreted as a real treatment effect.

Methods

Several statistical approaches have been developed to analyse such situations, including the algorithm of Mee and Chua which assumes a known population mean μ. We extend this approach to a situation where μ is unknown and suggest to vary it systematically over a range of reasonable values. Using differential calculus we provide formulas to estimate the range of μ where treatment effects are likely to occur when RTM is present.

Results

We successfully applied our method to three real world examples denoting situations when (a) no treatment effect can be confirmed regardless which μ is true, (b) when a treatment effect must be assumed independent from the true μ and (c) in the appraisal of results of uncontrolled studies.

Conclusion

Our method can be used to separate the wheat from the chaff in situations, when one has to interpret the results of uncontrolled studies. In meta-analysis, health-technology reports or systematic reviews this approach may be helpful to clarify the evidence given from uncontrolled observational studies.

Endothelin receptor antagonists improve exercise tolerance and oxygen saturations in patients with Eisenmenger syndrome and congenital heart defects

Patients with Eisenmenger syndrome experience substantial morbidity and decreased survival rates. In advanced cases, lung transplantation with cardiac repair or heart-lung transplantation is often the only option. The efficacy of endothelin receptor antagonists in Eisenmenger syndrome, which has similar pathophysiology to idiopathic pulmonary hypertension, remains unknown.We retrospectively studied adults with congenital heart disease and Eisenmenger syndrome who were treated with endothelin receptor antagonists. Analysis included chart reviews of clinical evaluations, oxygen saturation levels, functional class, 6-minute walk distances, and pulmonary artery pressures. In the 24 patients studied, Eisenmenger syndrome was caused by ventricular septal defect (6 patients), atrial septal defect (5), atrioventricular canal defect (3), complex congenital heart disease (9), and patent ductus arteriosus (1).Eisenmenger syndrome was treated with bosentan (21 patients) and sitaxsentan (3 patients). On average, therapy lasted 19 +/- 12 months. Subsequently, mean 6-minute walk distances improved from 226 +/- 159 m to 351 +/- 113 m (P = 0.004), and World Health Organization functional class improved > or =1 grade (P < 0.0001). Oxygen saturations increased on therapy from 80.5% to 87% (P < 0.0001). Pulmonary arterial systolic pressures decreased from 97 +/- 21 mmHg to 78 +/- 27 mmHg, and mean pressures from 59 +/- 16 mmHg to 47 +/- 17 mmHg (both P < 0.0001). Neither major complications from therapy nor changes in pulmonary capillary wedge pressure occurred.Endothelin receptor antagonists may play an important role in improving 6-minute walk distance, oxygen saturation, pulmonary artery pressures, and symptoms in adults who have congenital heart defects and Eisenmenger syndrome.

Long-term safety, tolerability and efficacy of bosentan in adults with pulmonary arterial hypertension associated with congenital heart disease

OBJECTIVE

To examine long-term safety and efficacy of bosentan--an oral dual endothelin receptor antagonist--in patients with pulmonary hypertension associated with congenital heart disease or Eisenmenger's syndrome.

DESIGN

Retrospective study.

SETTING

Tertiary cardiology referral centre.

PATIENTS

All adult patients with pulmonary arterial hypertension associated with congenital heart disease treated with bosentan at the Royal Brompton Adult Congenital Heart Centre were included.

MAIN OUTCOME MEASURES

Oxygen saturation, functional (WHO) class, 6-minute walk test distance and liver enzymes were analysed.

RESULTS

Eighteen patients (14 female) with pulmonary arterial hypertension associated with congenital heart disease (15 patients with Eisenmenger's syndrome) with a mean (SD) age of 41 (9) years (range 23-69) were included. Median follow-up was 29 months (range 1-39). One patient died during follow-up. Patients tolerated bosentan well and no significant rise in liver transaminases was seen. Arterial oxygen saturation remained stable throughout follow-up. Mean (SD) functional class (p = 0.001) and the 6-minute walk test distance improved compared with baseline (284 (144) vs 363 (124) m, 380 (91) m and 408 (114) m at baseline, 0-6 months, 6-12 months and 1-2 years of treatment, respectively; p<0.05 for each).

CONCLUSIONS

Bosentan appears to be safe and well tolerated in adults with pulmonary arterial hypertension associated with congenital heart disease or Eisenmenger's syndrome during mid- to long-term follow-up. In addition, functional class and the 6-minute walk test distance improved and this effect was maintained for up to 2 years of bosentan treatment.

Treatment of patients with Eisenmenger's syndrome with Bosentan

We treated prospectively 14 patients with Eisenmenger's syndrome, with a mean age of 10 years, ranging from 3 to 18 years. Treatment continued for 12 months, and demonstrated a lasting symptomatic improvement, but no improvement in terms of mean saturation of oxygen over 24 hours. Exercise capacity, as judged by peak uptake of oxygen, worsened in the six patients able to perform a treadmill test. The symptomatic benefit from dual blockage of endothelin receptors in these patients may be due to mechanisms other than selective pulmonary vasodilatation alone.

Pharmacologic treatment for pulmonary arterial hypertension

PURPOSE OF REVIEW

Pulmonary arterial hypertension (PAH) has been a disease with limited treatment options and poor prognosis. This article reviews the recent advances that took place in the medical management of PAH.

RECENT FINDINGS

Sildenafil is a type 5 cGMP-specific phosphodiesterase inhibitor originally developed to treat erectile dysfunction. Multiple uncontrolled and randomized controlled trials have proven that it is useful in the treatment of PAH and it was approved by the US Food and Drug Administration. The switch from continuous intravenous infusion of epoprostenol to subcutaneous infusion of treprostinil has been proven feasible and safe. Bosentan has been shown effective as a monotherapy and it also improves survival in patients with functional classes III and IV. In smaller clinical trials bosentan has improved symptoms in different forms of PAH. Combinations of drugs of different classes such as prostanoids, endothelin receptor blockers and sildenafil are tested, and such a strategy improves both symptoms and survival. Animal models and anecdotal clinical experience suggest the possibility of using imatinib mesylate in PAH.

SUMMARY

With the approval of sildenafil, treatment options for this difficult disease have improved significantly. Combinations of drugs of different groups are promising and need further exploration.

An open-label, multicentre pilot study of bosentan in pulmonary arterial hypertension related to congenital heart disease

BACKGROUND

Bosentan has been shown to be a safe and efficacious treatment for idiopathic pulmonary arterial hypertension (PAH) and PAH associated with connective tissue disease. However, there are limited studies examining the benefits of bosentan in PAH associated with congenital heart disease (CHD).

OBJECTIVE

The aim of the present pilot study was to explore the safety and efficacy of bosentan in patients with PAH associated with CHD.

PATIENTS AND METHODS

In the present study, 11 patients with PAH associated with CHD were enrolled to receive bosentan for a minimum of 16 weeks (62.5 mg twice a day for four weeks; thereafter 125 mg twice a day). Safety was assessed by monitoring adverse events, oxygen saturation, systemic blood pressure, pulse, complete blood count and liver function tests. Efficacy was assessed by the World Health Organization functional class, 6 min walk test (6-MWT), modified Borg dyspnea index, echocardiography and the 36-item short form health survey.

RESULTS

Ten patients completed the 16-week treatment period (one patient withdrew). Bosentan was not associated with a deterioration in resting oxygen saturation (83.0+/-4.6% at week 16 versus 81.9+/-6.1% at baseline; P = 0.402), or a deterioration in post-6-MWT oxygen saturation (70.1+/-10.9% at week 16 versus 68.7+/-15.1% at baseline; P = 0.747). Two patients experienced three serious adverse events. The distance walked in 6 min improved significantly by 28 m (P = 0.005) at week 16 compared with baseline, and the modified Borg dyspnea index also improved at week 16 compared with baseline (P = 0.050). The World Health Organization functional class improved from class III to class II for five of 10 patients (50%). Patients' self-rated quality of life (36-item short form health survey) demonstrated a nonsignificant improvement in each of the eight domains. Obtaining reliable echocardiographic measurements was difficult. Most echocardiographic parameters were only measurable on few patients, and none were measured on all patients, questioning the usefulness of echocardiography as a measuring tool for patients with complex CHD.

CONCLUSION

Bosentan was not associated with worsening of resting oxygen saturation or exercise systemic oxygen saturation, suggesting its potential as a safe treatment option for patients with PAH associated with CHD. Improved 6-MWT and the modified Borg dyspnea index also suggested the possibility of bosentan as an efficacious treatment option for these patients. The results of the present study provide evidence for the need and feasibility of a large randomized, placebo-controlled clinical trial.

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.

Long term effects of bosentan treatment in adult patients with pulmonary arterial hypertension related to congenital heart disease (Eisenmenger physiology): safety, tolerability, clinical, and haemodynamic effect

BACKGROUND

Oral bosentan is an established treatment for pulmonary arterial hypertension (PAH).

OBJECTIVE

To evaluate safety, tolerability, and clinical and haemodynamic effects of bosentan in patients with PAH related to congenital heart disease (CHD).

PATIENTS

22 patients with CHD related PAH (8 men, 14 women, mean (SD) age 38 (10) years) were treated with oral bosentan (62.5 mg x 2/day for the first 4 weeks and then 125 mg x 2/day).

MAIN OUTCOME MEASURES

Clinical status, liver enzymes, World Health Organisation (WHO) functional class, resting oxygen saturations and 6-min walk test (6MWT) were assessed at baseline and at 1, 3, 6, and 12 months. Haemodynamic evaluation with cardiac catheterisation was performed at baseline and at 12 month follow-up.

RESULTS

12 patients had ventricular septal defect, 5 atrioventricular canal, 4 single ventricle, and 1 atrial septal defect. All patients tolerated bosentan well. No major side effects were seen. After a year of treatment, an improvement was seen in WHO functional class (2.5 (0.7) v 3.1 (0.7); p<0.05), oxygen saturation at rest (87 (6%) v 81 (9); p<0.001), heart rate at rest (81 (10) v 87 (14) bpm; p<0.05), distance travelled in the 6MWT (394 (73) v 320 (108) m; p<0.001), oxygen saturation at the end of the 6MWT (71 (14) v 63 (17%); p<0.05), Borg index (5.3 (1.8) v 6.5 (1.3); p<0.001), pulmonary vascular resistances index (14 (9) v 22 (12) WU m(2); p<0.001), systemic vascular resistances index (23 (11) v 27 (10) WU.m(2); p<0.01), pulmonary vascular resistances index/systemic vascular resistances index (0.6 (0.5) v 0.9 (0.6); p<0.05); pulmonary (4.0 (1.3) v 2.8 (0.9) l/min/m2; p<0.001) and systemic cardiac output (4.2 (1.4) v 3.4 (1.1) l/min/m2; p<0.05).

CONCLUSIONS

Bosentan was safe and well tolerated in adults with CHD related PAH during 12 months of treatment. Clinical status, exercise tolerance, and pulmonary haemodynamics improved considerably.

Long-term oral bosentan treatment in patients with pulmonary arterial hypertension related to congenital heart disease: a 2-year study

OBJECTIVE

To evaluate the long-term clinical and exercise effect of chronic oral administration of the non-selective endothelin receptor antagonist bosentan in patients with pulmonary arterial hypertension (PAH) related to congenital heart disease (CHD).

DESIGN

Extension of a preceding prospective non-randomised open clinical study on bosentan treatment in PAH related to CHD.

SETTING

A tertiary referral centre for cardiology.

PATIENTS

19 of the original 21 patients of mean (standard deviation (SD)) age 22 (3) years (13 with Eisenmenger syndrome) in World Health Organization (WHO) class II-IV and having a mean (SD) oxygen saturation of 87 (2) %.

INTERVENTION

Patients received bosentan treatment for 2.4 (0.1) years and underwent clinical and exercise evaluation at baseline, 16 weeks and 2 years of treatment, with haemodynamic assessment at baseline and 16 weeks.

RESULTS

All patients remained stable with sustained subjective clinical and WHO class improvement (p<0.01) at 16 weeks and 2 years of treatment without significant side effects or changes in oxygen saturation. After the initial 16-week improvement (p<0.05) in peak oxygen consumption and exercise duration at treadmill test, and walking distance and Borg dyspnoea index at 6-min walk test, all exercise parameters appeared to return to their baseline values at 2 years of follow-up.

CONCLUSIONS

Long-term bosentan treatment in patients with PAH related to CHD is safe and induces clinical stability and improvement, but the objective exercise values appear to slowly return to baseline. Larger studies on long-term endothelin receptor antagonism including quality of life assessment are needed to evaluate the therapeutic role of bosentan in this population.

Bosentan in Eisenmenger syndrome and chronic thromboembolic pulmonary hypertension

BACKGROUND

Bosentan, a dual endothelin receptor antagonist, has been used for symptomatic improvement of patients with idiopathic pulmonary arterial hypertension (PAH) and specific types of secondary (e.g. scleroderma and human immunodeficiency virus infection) PAH, but its efficacy in patients with congenital heart disease and chronic thromboembolic pulmonary hypertension is still under evaluation. In this study two patients are presented, one with common atrioventricular canal and pulmonary hypertension and the other with recurrent pulmonary thromboembolism; both improved significantly after bosentan administration.

MATERIALS AND METHODS

The first patient was a 38-year-old female with trisomy 21, common atrioventricular canal and pulmonary hypertension (Eisenmenger syndrome). The second patient was a 57-year-old male, who was on anticoagulant therapy owing to an episode of pulmonary embolism that had been diagnosed 3 years earlier. Recurrent pulmonary thromboembolism was considered the most probable diagnosis. Chest spiral computed tomography examination excluded pulmonary endarterectomy as a therapeutic approach. At admission, the two patients were on New York Heart Association class IV, diagnosed by progressive rest dyspnea. Bosentan was administered to patients 1 and 2 for 6 and 9 months, respectively (62.5 mg b.i.d. for 4 weeks, then 125 mg b.i.d.).

RESULTS

Bosentan therapy resulted in significant clinical improvement in both patients. No hepatic dysfunction nor any other side-effect was observed.

CONCLUSIONS

Bosentan could be an effective therapy for pulmonary hypertension owing to congenital heart disease and chronic thromboembolic disease.

Bosentan Therapy in Patients With Eisenmenger Syndrome

Background— Eisenmenger syndrome is characterized by the development of pulmonary arterial hypertension with consequent intracardiac right-to-left shunt and hypoxemia in patients with preexisting congenital heart disease. Because Eisenmenger syndrome is associated with increased endothelin expression, patients may benefit from endothelin receptor antagonism. Theoretically, interventions that have some effect on the systemic vascular bed could worsen the shunt and increase hypoxemia.

Methods and Results— The Bosentan Randomized Trial of Endothelin Antagonist Therapy-5 (BREATHE-5) was a 16-week, multicenter, randomized, double-blind, placebo-controlled study evaluating the effect of bosentan, a dual endothelin receptor antagonist, on systemic pulse oximetry (primary safety end point) and pulmonary vascular resistance (primary efficacy end point) in patients with World Health Organization functional class III Eisenmenger syndrome. Hemodynamics were assessed by right- and left-heart catheterization. Secondary end points included exercise capacity assessed by 6-minute walk distance, additional hemodynamic parameters, functional capacity, and safety. Fifty-four patients were randomized 2:1 to bosentan (n=37) or placebo (n=17) for 16 weeks. The placebo-corrected effect on systemic pulse oximetry was 1.0% (95% confidence interval, −0.7 to 2.8), demonstrating that bosentan did not worsen oxygen saturation. Compared with placebo, bosentan reduced pulmonary vascular resistance index (−472.0 dyne · s · cm −5 ; P =0.0383). The mean pulmonary arterial pressure decreased (−5.5 mm Hg; P =0.0363), and the exercise capacity increased (53.1 m; P =0.0079). Four patients discontinued as a result of adverse events, 2 (5%) in the bosentan group and 2 (12%) in the placebo group.

Conclusions— In this first placebo-controlled trial in patients with Eisenmenger syndrome, bosentan was well tolerated and improved exercise capacity and hemodynamics without compromising peripheral oxygen saturation.