Efficacy and safety of bosentan for pulmonary arterial hypertension in adults with congenital heart disease

Comprehensive assessments of pulmonary circulation in children with pulmonary hypertension associated with congenital heart disease

Pulmonary hypertension associated with congenital heart disease (CHD-PH) encompasses different conditions confounded by the left-to-right shunt, left heart obstruction, ventricular dysfunction, hypoxia due to airway obstruction, dysplasia/hypoplasia of the pulmonary vasculature, pulmonary vascular obstructive disease, and genetic variations of vasoactive mediators. Pulmonary input impedance consists of the pulmonary vascular resistance (Rp) and capacitance (Cp). Rp is calculated as the transpulmonary pressure divided by the pulmonary cardiac output, whereas Cp is calculated as the pulmonary stroke volume divided by the pulmonary arterial pulse pressure. The plots of Rp and Cp demonstrate a unique hyperbolic relationship, namely, the resistor-capacitor coupling curve, which represents the pulmonary vascular condition. The product of Rp and Cp is the exponential pressure decay, which refers to the time constant. Alterations in Cp are more considerable in CHD patients at an early stage of developing pulmonary hypertension or with excessive pulmonary blood flow due to a left-to-right shunt. The importance of Cp has gained attention because recent reports have shown that low Cp potentially reflects poor prognosis in patients with CHD-PH and idiopathic pulmonary hypertension. It is also known that Cp levels decrease in specific populations, such as preterm infants and trisomy 21. Therefore, both Rp and Cp should be individually evaluated in the management of children with CHD-PH who have different disease conditions.

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.

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.

Gender-related differences in pulmonary arterial hypertension targeted drugs administration

During the last 15 years, a real "paradigm-shift" occurred, due to the development of PAH-targeted drugs, leading to crucial improvements in symptoms, exercise capacity, hemodynamics and outcome of PAH patients. In order to describe differences regarding epidemiology and therapy in PAH according to gender, we performed a review of the available literature in "PubMed" and "Web of Science" databases. In order to find relevant articles, we combined each of the following the keywords "pulmonary arterial hypertension", "gender", "sex", "men", "woman", "male", "female", "phosphodiesterase inhibitors", "endothelin receptor antagonists", "prostanoids". While there is a substantial agreement among epidemiological studies in reporting an increased prevalence of pulmonary arterial hypertension (PAH) among women, male PAH patients are affected by a higher impairment of the right ventricular function and consequently experience poorer outcomes. With regards to PAH-targeted drug administration, endothelin receptor antagonists (ERAs) and prostacyclin analogues (PC) show better treatment results in female PAH patients, while phosphodiesterase-5 inhibitors (PD5-I) seem to exert a more beneficial effect on male patients. However, to date no clear consensus could be formed by the available literature, which is constituted mainly by retrospective studies. Females with PAH are more prone to develop PAH, while males experience poorer outcomes. Females PAH might benefit more from ERAs and PC, while males seem to have more beneficial effects from PD5-I administration. However, more research is warranted in order to assess the most effective treatment for PAH patients according to gender.

Effect of dual pulmonary vasodilator therapy in pulmonary arterial hypertension associated with congenital heart disease: a retrospective analysis

BACKGROUND

Patients with pulmonary arterial hypertension (PAH) are managed according to evidence-based treatment guidelines.

METHODS AND RESULTS

In this single-centre retrospective analysis, we examined outcomes of patients with PAH caused by congenital heart disease (PAH-CHD) with respect to exercise capacity and survival of adults treated with either bosentan or sildenafil monotherapy or bosentan-sildenafil dual therapy between January 2007 and January 2014. Of the 82 patients analysed, 29 had Down syndrome; 54 (65.8%) received bosentan monotherapy, 16 (19.5%) sildenafil monotherapy and 12 (14.6%) dual therapy. Mean treatment duration was 2.5 years for all patients and 4.1 years for 38 patients treated for ≥2 years. Pooled patient and treatment data showed initial improvement followed by stabilisation in mean 6 min walk distance (6MWD). For Down and non-Down patients, mean 6MWD increased and then stabilised on bosentan monotherapy. Mean 6MWD of patients on dual therapy at the time of analysis was 246.3 m before PAH-specific therapy initiation, 211.9 m immediately prior to addition of a second therapy and 214.4 m at last visit while on dual therapy. 1, 2 and 3-year survival rates for all patients from time of treatment initiation were 96%, 87% and 80%, respectively.

CONCLUSIONS

For the majority of patients, monotherapy with a PAH-specific medication provided improved and sustained exercise benefits. For the small percentage of patients who required it, add-on therapy appeared to prevent further deterioration in exercise capacity but did not improve 6MWD.

Riociguat for pulmonary arterial hypertension associated with congenital heart disease

Objective

The Pulmonary Arterial hyperTENsion sGC-stimulator Trial-1 (PATENT-1) was a randomised, double-blind, placebo-controlled phase III trial evaluating riociguat in patients with pulmonary arterial hypertension (PAH). PATENT-2 was an open-label long-term extension to PATENT-1. Here, we explore the efficacy and safety of riociguat in the subgroup of patients with persistent/recurrent PAH after correction of congenital heart disease (PAH-CHD) from the PATENT studies.

Methods

In PATENT-1, patients received riociguat (maximum 2.5 or 1.5 mg three times daily) or placebo for 12 weeks; efficacy assessments included change from baseline to study end in 6-min walking distance (6MWD; primary), pulmonary vascular resistance (PVR), N-terminal of the prohormone of brain natriuretic peptide (NT-proBNP), WHO functional class (WHO FC) and time to clinical worsening. In PATENT-2, eligible patients from PATENT-1 received long-term riociguat (maximum 2.5 mg three times daily); the primary assessment was safety and tolerability. All PAH-CHD patients had a corrected cardiac defect.

Results

In PATENT-1, riociguat increased mean±SD 6MWD from baseline to week 12 by 39±60 m in patients with PAH-CHD versus 0±42 m for placebo. Riociguat also improved several secondary variables versus placebo, including PVR (−250±410 vs −66±632 dyn·s/cm⁵), NT-proBNP (−164±317 vs −46±697 pg/mL) and WHO FC (21%/79%/0% vs 8%/83%/8% improved/stabilised/worsened). One patient experienced clinical worsening (riociguat 1.5 mg group). Riociguat was well tolerated. In PATENT-2, riociguat showed sustained efficacy and tolerability in patients with PAH-CHD at 2 years.

Conclusions

Riociguat was well tolerated in patients with PAH-CHD and improved clinical outcomes including 6MWD, PVR, WHO FC and NT-proBNP.

Trial registration number

The clinical trials numbers are NCT00810693 for PATENT-1 and NCT00863681 for PATENT-2.

Can pulmonary vasodilator therapy expand the operative indications for congenital heart disease?

The operability of congenital heart disease with left to right shunt depends on the severity of the pulmonary vascular disease induced by the increased pulmonary blood flow. Although some recommendations exist regarding operative indications according to pathological, hemodynamic, and epidemiological factors, the evidence underlying these recommendations is not conclusive. Recently, oral pulmonary vasodilator therapy has been reported to improve outcomes in patients with idiopathic pulmonary arterial hypertension, and this therapy also appears to be effective in patients with congenital heart disease and pulmonary arterial hypertension, including those with postoperative pulmonary hypertension and Eisenmenger syndrome. It is expected that the availability of novel pulmonary vasodilator therapy will expand the operative indications in patients with congenital heart disease with left to right shunt, but there is currently insufficient evidence to definitively determine this. A multicenter double-blind study should be conducted to further examine this issue.

Randomized controlled trial using bosentan to enhance the impact of exercise training in subjects with type 2 diabetes mellitus

In type 2 diabetes patients, endothelin (ET) receptor blockade may enhance blood flow responses to exercise training. The combination of exercise training and ET receptor blockade may represent a more potent stimulus than training alone to improve vascular function, physical fitness and glucose homeostasis. We assessed the effect of an 8 week exercise training programme combined with either ET blockade or placebo on vasculature, fitness and glucose homeostasis in people with type 2 diabetes. In a double-blind randomized controlled trial, brachial endothelium-dependent and ‑independent dilatation (using flow-mediated dilatation and glyceryl trinitrate, respectively), glucose homeostasis (using Homeostasis Model Assessment for Insulin Resistance (HOMA-IR)) and physical fitness (maximal cycling test) were assessed in 18 men with type 2 diabetes (60 ± 6 years old). Subjects underwent an 8 week exercise training programme, with half of the subjects receiving ET receptor blockade (bosentan) and the other half a placebo, followed by reassessment of the tests above. Exercise training improved physical fitness to a similar extent in both groups, but we did not detect changes in vascular function in either group. This study suggests that there is no adaptation in brachial and femoral artery endothelial function after 8 weeks of training in type 2 diabetes patients. Endothelin receptor blockade combined with exercise training does not additionally alter conduit artery endothelial function or physical fitness in type 2 diabetes.

Long-term results of treatment with bosentan in adult Eisenmenger's syndrome patients with Down's syndrome related to congenital heart disease

Background

Patients with Down’s syndrome and shunt lesions are at high risk of developing pulmonary arterial hypertension (PAH) earlier than patients without Down’s syndrome. However, data on the efficacy of PAH-specific therapy in patients with Down’s syndrome are limited. The aim of this retrospective analysis was to determine the long-term efficacy of the dual endothelin receptor antagonist, bosentan, in Eisenmenger's syndrome (ES) patients with Down’s syndrome.

Methods

In this observational study adults with Down’s syndrome with a confirmed diagnosis of ES (World Health Organization functional class III) and receiving bosentan therapy and were followed up long term. Clinical evaluation at baseline and follow-up visits included resting transcutaneous arterial oxygen saturation and laboratory assessments. Exercise capacity was evaluated using a 6-minute walk test where transcutaneous arterial oxygen saturation at peak exercise (SpO₂), 6-minute walk distance (6MWD) and Borg dyspnoea index were assessed. A full echocardiographic assessment was conducted at baseline and follow-up visits.

Results

Overall, seven adults (mean age 29.6 ± 11.2 years; 57% male) received bosentan at a starting dose of 62.5 mg twice daily. This was increased to the target dose of 125 mg twice daily 4 weeks later. All patients remained on bosentan until the end of the study. After a mean (± standard deviation) duration of 52.2 ± 3.9 months (range: 46.0–55.5 months), 6MWD had increased from 199.6 ± 69.1 metres to 303.7 ± 99.9 metres (P < 0.05) and SpO₂ at the end of the 6-minute walk test had increased from 61.6 ± 7.6% to 74.7 ± 6.2% (P < 0.05). Echocardiography demonstrated a significant change in acceleration time from 62.9 ± 11.6 m/s to 83.0 ± 9.6 m/s (P = 0.0156), and acceleration time/ejection time ratio from the pulmonary flow from 0.24 ± 0.04 at baseline to 0.30 ± 0.02 (P = 0.0156) at final follow-up.

Conclusions

Long-term treatment with bosentan significantly improved exercise capacity and oxygen saturation following exercise in adult ES patients with Down’s syndrome. These data confirm that the presence of Down’s syndrome does not affect the response to oral bosentan therapy.

Effect of bosentan on exercise capacity and clinical worsening in patients with dual down and eisenmenger syndrome

This single-center, retrospective analysis evaluated long-term bosentan treatment in adult patients (n = 7) with both Down and Eisenmenger syndromes (DS-ES). Laboratory tests, 6-minute walk distance (6MWD), functional class, and Doppler echocardiography were assessed at baseline and during 2 years' follow-up. Improvements or maintenance of 6MWD were observed (68 m improvement from baseline at month 12) after bosentan initiation. 6MWD was maintained up to year 2. Overall, 6 patients experienced a significant improvement in functional class during 2 years' therapy (P = 0.01). There were no significant changes in parameters measured by Doppler echocardiography. None of the patients required either hospitalization or additional pulmonary arterial hypertension (PAH) therapy because of PAH progression. Bosentan treatment was generally well tolerated; no liver function abnormalities or serious adverse drug reactions were noted. In this DS-ES cohort, bosentan seemed to be well tolerated and clinically effective.

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.

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.