Long-term efficacy of bosentan in inoperable chronic thromboembolic pulmonary hypertension

Performance-based outcome measures for assessing physical capacity in patients with pulmonary embolism: A scoping review

INTRODUCTION

Up to 50 % of patients surviving a pulmonary embolism (PE) report persisting shortness of breath, reduced physical capacity and psychological distress. As the PE population is heterogeneous compared to other cardiovascular patient groups, outcome measures for assessing physical capacity traditionally used in cardiac populations may not be reliable for the PE population as a whole. This scoping review aims to 1) map performance-based outcome measures (PBOMs) used for assessing physical capacity in PE research, and 2) to report the psychometric properties of the identified PBOMs in a PE population.

METHODS

The review was conducted according to the Joanna Briggs Institute framework for scoping reviews and reported according to the PRISMA-Extension for Scoping Reviews guideline.

RESULTS

The systematic search of five databases identified 4585 studies, of which 243 studies met the inclusion criteria. Of these, 185 studies focused on a subgroup of patients with chronic thromboembolic pulmonary hypertension. Ten different PBOMs were identified in the included studies. The 6-minute walk test (6MWT) and cardiopulmonary exercise test (CPET) were the most commonly used, followed by the (Modified) Bruce protocol and Incremental Shuttle Walk test. No studies reported psychometric properties of any of the identified PBOMs in a PE population.

CONCLUSIONS

Publication of studies measuring physical capacity within PE populations has increased significantly over the past 5-10 years. Still, not one study was identified, reporting the validity, reliability, or responsiveness for any of the identified PBOMs in a PE population. This should be a priority for future research in the field.

Comparative Efficacy and Safety of Targeted Therapies for Chronic Thromboembolic Pulmonary Hypertension: A Systematic Review and Network Meta-Analysis

Background

There is significant controversy relating to whether chronic thromboembolic pulmonary hypertension (CTEPH) can be treated with pulmonary arterial hypertension- (PAH-) targeted therapies and which therapy is the optimal choice for patients. A large number of randomized controlled trials (RCTs) have compared PAH-targeted therapies with placebo or conventional therapies. In this study, we aimed to compare all of the PAH-targeted medications that are used to treat CTEPH and rank their efficacy by the application of network meta-analysis (NMA).

Methods

We searched PubMed, EMBASE, Web of Science, the Cochrane Central Register, https://clinicaltrials.gov, and who.int/trialsearch/, for relevant RCTs published up to January 2020. In addition to traditional meta-analysis, we also performed NMA in our systematic review, as deployed in a previous protocol (PROSPERO: CRD42020173765).

Results

Our study identified eight eligible RCTs that evaluated seven PAH-targeted therapies in 703 patients with CTEPH. NMA revealed that riociguat was ranked first as the most optimized therapy for ameliorating the 6-minute walk distance with a probability of 80.4%. Bosentan was significantly better than others with regard to reducing brain natriuretic peptide/N-terminal pro-B-type natriuretic peptide with a probability of 84.3%. Sildenafil was identified as the best drug in terms of improving the New York Heart Association/World Health Organization functional class with a probability of 87.3%. Treprostinil and macitentan were more beneficial than other drugs in reducing pulmonary vascular resistance and lowering the incidence of clinical worsening with probabilities of 86.2% and 79.2%, respectively.

Conclusion

Analysis revealed positive advantages for the use of PAH-targeted drugs in patients with CTEPH. Overall, treprostinil and riociguat were superior to all other PAH-targeted medications in most of the outcomes investigated.

Comparison of Balloon Pulmonary Angioplasty and Pulmonary Vasodilators for Inoperable Chronic Thromboembolic Pulmonary Hypertension: A Systematic Review and Meta-Analysis

Treatment options for chronic thromboembolic pulmonary hypertension (CTEPH) that is not amenable to thromboendarterectomy or is recurrent/persistent after thromboendarterectomy (inoperable CTEPH) include pulmonary vasodilators or balloon pulmonary angioplasty (BPA). We compared efficacy and safety outcomes of BPA with or without pulmonary vasodilators to pulmonary vasodilator therapy alone in patients with inoperable CTEPH. Observational and randomized trial data reporting outcomes for >5 patients with inoperable CTEPH were sought. Single-arm random effects meta-analyses were performed. The primary outcome was change in six-minute walk distance (6MWD). Secondary outcomes included safety; World Health Organization functional class (WHO FC); and change in mean pulmonary arterial pressure (mPAP), pulmonary vascular resistance (PVR), and cardiac index. Thirty-four studies with 1604 patients were eligible for analyses. Both treatments resulted in significant improvement in 6MWD (71.0 meters, 95% CI: 47.4–94.5 meters with BPA versus 47.8 meters, 95% CI: 34.5–61.2 meters with pulmonary vasodilators), PVR [−3.1 Wood Units (WU), 95% CI: −4.9 to −1.4 WU versus −1.6 WU, 95% CI: −2.4 to −0.8 WU] and mPAP (−14.8 mmHg, 95% CI: −18.2 to −11.5 mmHg versus −4.9 mmHg, 95% CI: −6.9 to −2.8 mmHg). Cardiac index was similar and most patients were WHO FC II and III after their respective interventions. More complications occurred in the BPA arm. In conclusion, BPA and pulmonary vasodilators both improve 6MWD and hemodynamics in patients with inoperable CTEPH. While BPA may offer greater functional and hemodynamic improvements, this technique carries the accompanying risks of an invasive procedure.

Advances in targeted therapy for chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by unresolved thrombi in the pulmonary arteries and microvasculopathy in nonoccluded areas. If left untreated, progressive pulmonary hypertension will induce right heart failure and, finally, death. Currently, pulmonary endarterectomy (PEA) remains the only method that has the potential to cure CTEPH. Unfortunately, up to 40% of patients are ineligible for this procedure for various reasons. In recent years, refined balloon pulmonary angioplasty (BPA) has become an alternative option for inoperable CTEPH patients, and it may be another curative treatment in the future, particularly in combination with prior PEA. Nevertheless, 23% of patients still suffer from persistent PH after BPA. Given that CTEPH shares many similarities with idiopathic pulmonary arterial hypertension (PAH), targeted drugs developed for PAH are also attractive options for CTEPH, especially for inoperable or persistent/recurrent CTEPH patients. To date, riociguat, macitentan, and subcutaneous treprostinil are the only drugs proven by randomized control trials to be capable of improving the exercise capacity (6-min walking distance) of CTEPH patients. In this review, we summarize the achievements and unresolved problems of PAH-targeted therapy for CTEPH over the last decade.

Pharmacological therapy for patients with chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare but life-threatening disease resulting from unresolved thromboembolic obstructions. Pulmonary endarterectomy (PEA) surgery is the gold-standard treatment as it is potentially curative; however, not all patients are deemed operable and up to one-third have persistent or recurrent CTEPH after the procedure. Pulmonary arterial hypertension (PAH) and CTEPH have similar clinical presentations and histopathological features, so agents shown to be effective in PAH have often been prescribed to patients with CTEPH in the absence of proven therapies. However, clinical evidence for this strategy is not compelling. A number of small uncontrolled trials have investigated endothelin receptor antagonists, prostacyclin analogues and phosphodiesterase type 5 inhibitors in CTEPH with mixed results, and a phase III study of the endothelin receptor antagonist bosentan met only one of its two co-primary end-points. Recently, however, the soluble guanylate cyclase stimulator, riociguat, was approved in the USA and Europe for the treatment of inoperable or persistent/recurrent CTEPH following positive results from the phase III CHEST study (Chronic Thromboembolic Pulmonary Hypertension Soluble Guanylate Cyclase–Stimulator Trial). This article reviews the current evidence for the use of pharmacological therapies in CTEPH.

A review of pharmacological treatment of inoperable or persistent/recurrent CTEPH and the future standard of carehttp://ow.ly/KMUQV

Bosentan inhibits oxidative and nitrosative stress and rescues occlusive pulmonary hypertension

Pulmonary arterial hypertension (PH) is a fatal disease marked by excessive pulmonary vascular cell proliferation. Patients with idiopathic PH express endothelin-1 (ET-1) at high levels in their lungs. As the activation of both types of ET-1 receptor (ETA and ETB) leads to increased generation of superoxide and hydrogen peroxide, this may contribute to the severe oxidative stress found in PH patients. As a number of pathways may induce oxidative stress, the particular role of ET-1 remains unclear. The aim of this study was to determine whether inhibition of ET-1 signaling could reduce pulmonary oxidative stress and attenuate the progression of disease in rats with occlusive-angioproliferative PH induced by a single dose of SU5416 (200 mg/kg) and subsequent exposure to hypoxia for 21 days. Using this regimen, animals developed severe PH as evidenced by a progressive increase in right-ventricle (RV) peak systolic pressure (RVPSP), severe RV hypertrophy, and pulmonary endothelial and smooth muscle cell proliferation, resulting in plexiform vasculopathy. PH rats also had increased oxidative stress, correlating with endothelial nitric oxide synthase uncoupling and NADPH oxidase activation, leading to enhanced protein nitration and increases in markers of vascular remodeling. Treatment with the combined ET receptor antagonist bosentan (250 mg/kg/day; day 10 to 21) prevented further increase in RVPSP and RV hypertrophy, decreased ETA/ETB protein levels, reduced oxidative stress and protein nitration, and resulted in marked attenuation of pulmonary vascular cell proliferation. We conclude that inhibition of ET-1 signaling significantly attenuates the oxidative and nitrosative stress associated with PH and prevents its progression.

Clinical worsening during long-term follow-up in inoperable chronic thromboembolic pulmonary hypertension

BACKGROUND

Pulmonary endarterectomy is the treatment of choice in chronic thromboembolic pulmonary hypertension (CTEPH). Modern pulmonary vasoactive medication (like endothelin receptor antagonists, phosphodiesterase type 5 inhibitors, and prostacyclins) is used in patients with an inoperable disease and improved prognosis. We evaluate mortality and time to clinical worsening (TtCW) in inoperable CTEPH patients during long-term follow-up.

METHODS

All 32 patients with inoperable CTEPH were enrolled between June 2002 and January 2009. TtCW was defined as the combination of death, need for intravenous pulmonary arterial hypertension medication, or 15% decrease in 6-minute walk distance (6-MWD) without improvement in functional class. The Cox proportional hazard regression was used to identify predictors.

RESULTS

During a mean follow-up of 3.4 years (range = 0.2-10.2 years), 11 patients died (34%). The 1- and 3-year survival rates were 87 and 77%, respectively. Baseline functional class, 6-MWD, mean pulmonary artery pressure, and pulmonary vascular resistance were predictors for survival. Clinical worsening occurred in 16 patients (50%). The 1- and 3-year rates of freedom from clinical worsening were 74 and 60%, respectively. The only predictor for clinical worsening was the baseline 6-MWD.

CONCLUSION

Despite the improvement in medical treatment of inoperable CTEPH, the mortality rate is still high, and clinical worsening occurred in a substantial number of patients during a follow-up of more than 3 years.

Long-term efficacy of bosentan in inoperable chronic thromboembolic pulmonary hypertension

Background. Inoperable chronic thromboembolic pulmonary hypertension (CTEPH) is associated with a poor survival.Objectives. To evaluate the long-term response to a dual endothelin receptor antagonist in patients with inoperable CTEPH.Methods. All consecutive 18 patients (mean age 63+/-14 years) treated with bosentan for symptomatic inoperable CTEPH were included. Efficacy was evaluated by the log value of serum levels of N-terminal-pro brain natriuretic peptide (log NTpro BNP), New York Heart Association functional class (NYHA), and the six-minute walk test (6-MWT). All follow-up data (median 31 months) were compared with baseline and divided into: short-term (<12 months), mid-term (between 12 and 24 months), and long-term follow-up (>24 months).Results. At baseline, 15 patients were in NYHA class III and three in NYHA class IV, mean log NT-pro BNP level was 7.2+/-1.4 log pg/ml, and mean 6-MWT distance was 404+/-125 m. During short-term follow-up (n=18), the NYHA class improved (p=0.001), 6-MWT distance increased by 33 m (p=0.03), and log NT-pro BNP decreased to 6.9+/-1.4 log pg/ml (p=0.007). During mid-term follow-up (n=17), the NYHA class improved (p<0.001), the mean 6-MWT distance increased by 41 m (p=0.01), and log NT-pro BNP was 6.9+/-1.4 log pg/ml (p=0.31). During late followup (n=14) the NYHA class was still improved (p=0.03), the 6-MWT distance decreased by 9 m (p=0.73), and log NT-pro BNP was 7.1+/-1.5 log pg/ml (p=0.91). The overall four year survival rate was 88%.

CONCLUSION

Bosentan seems to be effective during long-term treatment in patients with inoperable CTEPH. (Neth Heart J 2009;17:329-33.).