Bosentan for Treatment of Inoperable Chronic Thromboembolic Pulmonary Hypertension

Guidelines on the Diagnosis and Treatment of Pulmonary Hypertension: Summary of Recommendations

Pulmonary hypertension is a hemodynamic disorder defined by abnormally high pulmonary artery pressure that can occur in numerous diseases and clinical situations. The causes of pulmonary hypertension are classified into 5 major groups: arterial, due to left heart disease, due to lung disease and/or hypoxemia, chronic thromboembolic, with unclear and/or multifactorial mechanisms. This is a brief summary of the Guidelines on the Diagnostic and Treatment of Pulmonary Hypertension of the Spanish Society of Pulmonology and Thoracic Surgery. These guidelines describe the current recommendations for the diagnosis and treatment of the different pulmonary hypertension groups.

Riociguat in patients with chronic thromboembolic pulmonary hypertension: results from an early access study

Background

Following positive results from the Phase III CHEST-1 study in patients with inoperable or persistent/recurrent chronic thromboembolic pulmonary hypertension (CTEPH), the Phase IIIb CTEPH early access study (EAS) was designed to assess the safety and tolerability of riociguat in real-world clinical practice, as well as to provide patients with early access to riociguat before launch. Riociguat is approved for the treatment of inoperable and persistent/recurrent CTEPH.

Methods

We performed an open-label, uncontrolled, single-arm, early access study in which 300 adult patients with inoperable or persistent/recurrent CTEPH received riociguat adjusted from 1 mg three times daily (tid) to a maximum of 2.5 mg tid. Patients switching from unsatisfactory prior pulmonary arterial hypertension (PAH)-targeted therapy (n = 84) underwent a washout period of at least 3 days before initiating riociguat. The primary aim was to assess the safety and tolerability of riociguat, with World Health Organization functional class and 6-min walking distance (6MWD) as exploratory efficacy endpoints.

Results

In total, 262 patients (87%) completed study treatment and entered the safety follow-up (median treatment duration 47 weeks). Adverse events were reported in 273 patients (91%). The most frequently reported serious adverse events were syncope (6%), right ventricular failure (3%), and pneumonia (2%). There were five deaths, none of which was considered related to study medication. The safety and tolerability of riociguat was similar in patients switched from other PAH-targeted therapies and those who were treatment naïve. In patients with data available, mean ± standard deviation 6MWD had increased by 33 ± 42 m at Week 12 with no clinically relevant differences between the switched and treatment-naïve subgroups.

Conclusions

Riociguat was well tolerated in patients with CTEPH who were treatment naïve, and in those who were switched from other PAH-targeted therapies. No new safety signals were observed.

Trial registration

ClinicalTrials.org NCT01784562. Registered February 4, 2013.

Electronic supplementary material

The online version of this article (10.1186/s12890-017-0563-7) contains supplementary material, which is available to authorized users.

The changing landscape of chronic thromboembolic pulmonary hypertension management

For patients with chronic thromboembolic pulmonary hypertension (CTEPH), the current standard of care involves surgical removal of fibro-thrombotic obstructions by pulmonary endarterectomy. While this approach has excellent outcomes, significant proportions of patients are not eligible for surgery or suffer from persistent/recurrent pulmonary hypertension after the procedure. The availability of balloon pulmonary angioplasty and the approval of the first medical therapy for use in CTEPH have significantly improved the outlook for patients ineligible for pulmonary endarterectomy. In this comprehensive review, we discuss the latest developments in the rapidly evolving field of CTEPH. These include improvements in imaging modalities and advances in surgical and interventional techniques, which have broadened the range of patients who may benefit from such procedures. The efficacy and safety of targeted medical therapies in CTEPH patients are also discussed, particularly the encouraging data from the recent MERIT-1 trial, which demonstrated the beneficial impact of using macitentan to treat patients with inoperable CTEPH, including those on background therapy. As the treatment options for CTEPH improve, hybrid management involving more than one intervention in the same patient may become a viable option in the near future.

Management of CTEPH is evolving rapidly, leading to improved patient outcomeshttp://ow.ly/rHrt30gUQWX

N-terminal pro-B-type natriuretic peptide for monitoring after balloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension

BACKGROUND

Balloon pulmonary angioplasty (BPA) is an emerging interventional treatment option for chronic thromboembolic pulmonary hypertension (CTEPH). The non-invasive monitoring of CTEPH patients is a clinical challenge. In this study we examined changes in N-terminal pro-B-type natriuretic peptide (NT-proBNP) in patients undergoing BPA for inoperable CTEPH and related them to peri-procedural success.

METHODS

In this study we analyzed a total of 51 consecutive patients who underwent BPA treatment and completed a 6-month follow-up (6-MFU) between March 2014 and March 2017. Serum samples for NT-proBNP measurement were collected before every BPA and at 6-MFU.

RESULTS

The 51 patients underwent 265 interventions involving angioplasty of a total of 410 vessels. The 6-month survival rate was 96.1%. The baseline (BL) mean pulmonary artery pressure (PAP) was 39.5 ± 12.1 mm Hg, pulmonary vascular resistance (PVR) was 515.8 ± 219.2 dynes/s/cm⁵ and the median NT-proBNP level was 820 (153 to 1,871.5) ng/liter. At BL, World Health Organization functional class (FC) was ≥III in 96.1% of the patients, whereas, at 6-MFU, 11.8% were in WHO FC ≥III. At 6-MFU, mean PAP (32.6 ± 12.6 mm Hg; p < 0.001), PVR (396.9 ± 182.6 dynes/s/cm⁵; p < 0.001) and NT-proBNP (159.3 [84.4 to 464.3] ng/liter; p < 0.001) levels were reduced. The decrease in NT-proBNP levels correlated with the decrease in mean PAP (r_rs = 0.43, p = 0.002) and PVR (r_rs = 0.50, p = 0.001). A reduction in the NT-proBNP level of 46% indicated a decrease in mean PAP of ≥25% (area under the curve [AUC] = 0.71) and a reduction of 61% indicated a decrease in PVR of ≥35% (AUC 0.77).

CONCLUSIONS

Our results demonstrate that NT-proBNP levels decrease after BPA, providing valuable evidence of procedural success. NT-proBNP measurement allows identification of patients who are BPA non-responders and may thus be a valuable adjunct in therapy monitoring.

Medical Management of Pulmonary Hypertension with Unclear and/or Multifactorial Mechanisms (Group 5): Is There a Role for Pulmonary Arterial Hypertension Medications?

PURPOSE OF REVIEW

The purpose of this review was to outline the mechanisms and to review recent literature on pulmonary arterial hypertension (PAH) medications in group 5 pulmonary hypertension (PH).

RECENT FINDINGS

The first steps in management are to understand the mechanisms and hemodynamic profile and to exclude chronic thromboembolic disease. Recent studies in the past 5 years have found that PAH medications may improve hemodynamics in patients with pre-capillary pulmonary hypertension due to sarcoidosis, pulmonary Langerhans cell histiocytosis, lymphangioleiomyomatosis, and myeloproliferative disorders with dasatinib-induced PH. Improvements in exercise capacity are uncommon, and no survival benefit has been demonstrated. There is a risk of pulmonary edema in patients with pulmonary venous involvement or fibrosing mediastinitis when treated with PAH therapies. There is limited evidence supporting the use of PAH medications in group 5 patients, and they may be harmful in certain cases. In most patients with group 5 PH, treatment should be directed to the underlying disease with PAH therapies reserved for patients with severe pre-capillary PH.

Macitentan for the treatment of inoperable chronic thromboembolic pulmonary hypertension (MERIT-1): results from the multicentre, phase 2, randomised, double-blind, placebo-controlled study

BACKGROUND

Macitentan is beneficial for long-term treatment of pulmonary arterial hypertension. The microvasculopathy of chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension are similar.

METHODS

The phase 2, double-blind, randomised, placebo-controlled MERIT-1 trial assessed macitentan in 80 patients with CTEPH adjudicated as inoperable. Patients identified as WHO functional class II-IV with a pulmonary vascular resistance (PVR) of at least 400 dyn·s/cm5 and a walk distance of 150-450 m in 6 min were randomly assigned (1:1), via an interactive voice/web response system, to receive oral macitentan (10 mg once a day) or placebo. Treatment with phosphodiesterase type-5 inhibitors and oral or inhaled prostanoids was permitted for WHO functional class III/IV patients. The primary endpoint was resting PVR at week 16, expressed as percentage of PVR measured at baseline. Analyses were done in all patients who were randomly assigned to treatment; safety analyses were done in all patients who received at least one dose of the study drug. This study is registered with ClinicalTrials.gov, number NCT02021292.

FINDINGS

Between April 3, 2014, and March 17, 2016, we screened 186 patients for eligibility at 48 hospitals across 20 countries. Of these, 80 patients in 36 hospitals were randomly assigned to treatment (40 patients to macitentan, 40 patients to placebo). At week 16, geometric mean PVR decreased to 73·0% of baseline in the macitentan group and to 87·2% in the placebo group (geometric means ratio 0·84, 95% CI 0·70-0·99, p=0·041). The most common adverse events in the macitentan group were peripheral oedema (9 [23%] of 40 patients) and decreased haemoglobin (6 [15%]).

INTERPRETATION

In MERIT-1, macitentan significantly improved PVR in patients with inoperable CTEPH and was well tolerated.

FUNDING

Actelion Pharmaceuticals Ltd.

Consequences of Venous Thromboembolism, Including Chronic Thromboembolic Pulmonary Hypertension

Venous thromboembolism includes both deep vein thrombosis and pulmonary embolism. They pose a significant risk for morbidity and mortality. In an appropriate clinical setting, invasive interventions, including administration of thrombolytics, anticoagulation, and placement of vena cava filter, are warranted. Bleeding, postthrombotic syndrome, recurrence, and filter-associated complications are few of the complications of this disease. More recently, chronic thromboembolic pulmonary hypertension has gained clinical interest in patients with pulmonary embolism and has warranted close follow-up.

Treatment of Chronic Thromboembolic Pulmonary Hypertension: The Role of Medical Therapy and Balloon Pulmonary Angioplasty

Chronic thromboembolic pulmonary hypertension (CTEPH) is a potentially curable disease when treated with pulmonary thromboendarterectomy (PTE). However, even at experienced surgical centers, nearly one-third of patients with CTEPH will be deemed inoperable for reasons including distal disease, comorbidities, or out-of-proportion pulmonary hypertension. It is in these patients with inoperable CTEPH that pulmonary hypertension (PH)-targeted medical therapy and balloon pulmonary angioplasty have potential therapeutic value. Previous unblinded cohort trials have assessed PH-targeted medical therapy in various subpopulations of CTEPH patients using epoprostenol, treprostinil, sildenafil, bosentan, and iloprost, each demonstrating measurable pulmonary hemodynamic effects. However, riociguat, a soluble guanylate cyclase stimulator, is the first FDA-approved therapy for inoperable CTEPH to demonstrate both an improvement in functional capabilities (6-minute walk time) as well as significant gains in secondary pulmonary hemodynamic end points in a large placebo-controlled trial. Balloon pulmonary angioplasty is an interventional procedure using telescoping catheters placed in the pulmonary arteries, through which wires and balloons are used to mechanically disrupt chronic clot material and relieve pulmonary vascular obstruction. Contemporary case series from multiple centers worldwide have demonstrated pulmonary hemodynamic improvement with this approach. As a result of these advances, patients with inoperable CTEPH who had few options as recently as 5 years ago now have alternatives with emerging evidence of therapeutic efficacy.

The anticoagulant effects of warfarin and the bleeding risk associated with its use in patients with chronic thromboembolic pulmonary hypertension at a specialist center in Japan: a retrospective cohort study

Patients with chronic thromboembolic pulmonary hypertension (CTEPH) require lifelong anticoagulation therapy. However, the bleeding risk and recurrence of venous thromboembolism (VTE) in CTEPH patients who are administered warfarin have not been adequately evaluated. The purpose of this study was to evaluate the risk of clinically relevant bleeding, recurrent VTE, and clinical worsening in patients with CTEPH who were administered warfarin.

The clinical records of 72 patients with CTEPH who regularly visited our institution and were administered warfarin were retrospectively reviewed between 1 January 2011 and 31 December 2015. We investigated the incidence of clinically relevant bleeding events, recurrent VTE, and hospitalization for the deterioration of pulmonary hypertension or right heart failure (RHF) during the observation period.

The mean observation period for the 72 patients was 3.60 ± 1.60 person-years. Clinically relevant bleeding, RHF, and recurrent VTE occurred in 21 (29.2%), eight (11.1%), and three (4.2%) of 72 patients, respectively, and the incidence rates for these events were 8.1%/person-year, 3.1%/person-year, and 1.2%/person-year, respectively. The incidence rates for the major and non-major bleeding events were 5.0%/person-year and 3.9%/person-year, respectively. The incidence of clinically relevant bleeding events was 20.8%/person-year during medical treatment with a soluble guanylate cyclase stimulator. One of 35 patients (2.9%) during the post-pulmonary endarterectomy period experienced hemoptysis during observation period (> 6 months after pulmonary endarterectomy). No bleeding events occurred during the post-balloon pulmonary angioplasty period.

In conclusion, warfarin effectively prevents VTE recurrence in CTEPH patients, but its effects may be associated with a considerable bleeding risk.

Balloon pulmonary angioplasty for inoperable patients with chronic thromboembolic pulmonary hypertension: the initial German experience

Balloon pulmonary angioplasty (BPA) is an emerging treatment for patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH).We report on a prospective series of 56 consecutive patients who underwent 266 BPA interventions (median, five per patient) at two German institutions. All patients underwent a comprehensive diagnostic work-up including right heart catheterisation at baseline and 24 weeks after their last intervention.BPA resulted in improvements in WHO functional class, 6 min walk distance (mean change, +33 m), right ventricular function and haemodynamics, including a decline in mean pulmonary artery pressure by 18% and in pulmonary vascular resistance by 26%. Procedure-related adverse events occurred in 9.4% of the interventions. The most common complications were related to pulmonary vascular injury and consecutive pulmonary bleeding. Most of these events were asymptomatic and self-limiting, but one patient died from pulmonary bleeding, resulting in a mortality rate of 1.8%.BPA resulted in haemodynamic and clinical improvements but was also associated with a considerable number of complications, including one fatal pulmonary bleeding. As the effects of BPA on survival are unknown, randomised controlled outcome trials comparing BPA with approved medical therapies in patients with inoperable CTEPH are required to allow for appropriate risk-benefit assessments.

A Review of Clinical Trial Endpoints of Patients with Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension and How They Relate to Patient Outcomes in the United States

Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are subgroups of pulmonary hypertension and are considered rare diseases. Understanding how endpoints of clinical trials (and patient registry studies) of patients with PAH and CTEPH are associated with patient outcomes is important in order to address the concerns of patients, health care providers, decision makers, and payers. The purpose of this review was to examine how endpoints used in clinical trials and patient registry studies are associated with outcomes of patients with PAH and CTEPH. A PubMed literature search was conducted to retrieve published studies, including randomized phase III clinical trials and observational studies, from years 2000 to May 2015 that evaluated the associations between change in 6-minute walking distance (6MWD), 6MWD thresholds, change in World Health Organization functional class (WHO-FC), and time to clinical worsening with outcomes of patients with PAH and CTEPH. Based on this review of published literature, a reduction in 6MWD as a criterion for PAH worsening, a deterioration in WHO-FC, and delay in the time to clinical worsening are clinically meaningful trial endpoints and are associated with outcomes of patients with PAH and CTEPH. Utilization and standardization of these endpoints will be useful for comparing interventions of clinical trials and therapies. Hospitalizations are frequent among patients with PAH and CTEPH, and total health care costs are high. From a U.S. payer perspective, clinical worsening is an important composite endpoint in that it includes hospitalization, which can be transformed into a preventative cost value associated with efficacious treatment of patients with PAH and CTEPH. In view of the greater number of medications available to treat PAH, the introduction of the first approved therapy to treat CTEPH, and the increasing use of combination pharmacotherapy, reliable prognostic markers of treatment responsiveness are important to help guide appropriate management. As new clinical trials and observational studies are conducted, it will be important to maintain universal endpoints so that health care providers, decision makers, and payers can better understand the value of targeted pharmacotherapies and combination therapies for the treatment of patients with PAH and CTEPH.

DISCLOSURES

Sponsorship for this review and article processing charges were funded by Bayer HealthCare Pharmaceuticals. Divers and Platt are employees of Bayer HealthCare Pharmaceuticals. Wang is an employee of Bayer HealthCare Pharmaceuticals and owns stock in the company. Lin and Lingohr-Smith are employees of Novosys Health, which received research funds from Bayer HealthCare Pharmaceuticals in connection with conducting this review and developing this manuscript. Mathai is a consultant to Bayer HealthCare Pharmaceuticals and also reports consulting fees from Actelion and Gilead. Study concept and design were contributed by Divers, Platt, Lin, and Mathai. Lin and Lingohr-Smith collected the data, and data interpretation was performed by Divers, Platt, Wang, and Matthai. The manuscript was written primarily by Lingohr-Smith, with assistance from the other authors, and revised by Divers, Platt, Wang, and Mathai.

ANMCO Position Paper: long-term follow-up of patients with pulmonary thromboembolism

Venous thromboembolism (VTE), including pulmonary embolism and deep venous thrombosis, is the third most common cause of cardiovascular death. The management of the acute phase of VTE has already been described in several guidelines. However, the management of the follow-up (FU) of these patients has been poorly defined. This consensus document, created by the Italian cardiologists, wants to clarify this issue using the currently available evidence in VTE. Clinical and instrumental data acquired during the acute phase of the disease are the cornerstone for planning the FU. Acquired or congenital thrombophilic disorders could be identified in apparently unprovoked VTE during the FU. In other cases, an occult cancer could be discovered after a VTE. The main targets of the post-acute management are to prevent recurrence of VTE and to identify the patients who can develop a chronic thromboembolic pulmonary hypertension. Knowledge of pathophysiology and therapeutic approaches is fundamental to decide the most appropriate long-term treatment. Moreover, prognostic stratification during the FU should be constantly updated on the basis of the new evidence acquired. Currently, the cornerstone of VTE treatment is represented by both the oral and the parenteral anticoagulation. Novel oral anticoagulants should be an interesting alternative in the long-term treatment.

Riociguat: a soluble guanylate cyclase stimulator for the treatment of pulmonary hypertension

Despite advances in treatments and improved survival, patients with pulmonary hypertension still experience poor exercise and functional capacity, which has a significant detrimental impact on their quality of life. The nitric oxide (NO)–soluble guanylate cyclase (sGC)–cyclic guanosine 3′,5′-monophosphate (cGMP) pathway has been shown to play an important role in cardiovascular physiology, especially in vasodilation and pulmonary vascular tone. The oral sGC stimulator riociguat has a dual mode of action on the NO–sGC–cGMP pathway: direct stimulation of sGC independent of NO and indirect simulation via sensitization of sGC to endogenous NO. Riociguat is now licensed in >50 countries worldwide, including in Europe, the USA, Canada, and Japan. Approval for the treatment of pulmonary arterial hypertension (PAH) was based on Phase III data from the PATENT studies, in which riociguat significantly improved exercise capacity, pulmonary vascular resistance, a range of secondary end points, and hemodynamic parameters in patients with symptomatic PAH. In the Phase III CHEST studies, riociguat consistently improved exercise capacity in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH) or persistent/recurrent CTEPH after pulmonary endarterectomy and is now the only drug to be approved for this indication. Riociguat was well tolerated in long-term studies of PAH and CTEPH. This review describes the role of the NO–sGC–cGMP pathway in the pathophysiology of pulmonary hypertension, and reviews the clinical efficacy and safety of riociguat in patients with PAH and inoperable or persistent/recurrent CTEPH. Based on its demonstrated efficacy and established safety profile, riociguat is a promising treatment option for patients with PAH and CTEPH.

Haemodynamic effects of riociguat in inoperable/recurrent chronic thromboembolic pulmonary hypertension

OBJECTIVE

We compared the haemodynamic effects of riociguat in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH) or persistent/recurrent CTEPH after pulmonary endarterectomy in the Chronic Thromboembolic Pulmonary Hypertension Soluble Guanylate Cyclase-Stimulator Trial 1 study.

METHODS

Patients with inoperable or persistent/recurrent CTEPH (n=261; mean± SD age 59±14 years; 66% women) were randomised to riociguat (up to 2.5 mg three times daily) or placebo. Haemodynamic parameters were assessed at baseline and week 16.

RESULTS

Riociguat decreased pulmonary vascular resistance (PVR) in inoperable (n=189; least-squares mean difference: -285 dyn s/cm5 (95% CI -357 to -213); p<0.0001) and persistent/recurrent (n=72; -131 dyn s/cm5 (95% CI -214 to -48); p=0.0025) patients. Cardiac index improved in inoperable patients by a least-squares mean difference of +0.6 L/min/m2 (95% CI 0.4 to 0.7; p<0.0001), while in persistent/recurrent patients the change was +0.2 L/min/m2 (95% CI -0.1 to 0.5; p=0.17). Mean pulmonary artery pressure decreased in inoperable and persistent/recurrent patients(-4.7 mm Hg (95% CI -6.9 to -2.6; p<0.0001 and -4.8 mm Hg (-8.2 to -1.5; p=0.0055), respectively). For all patients, changes in 6 min walk distance correlated with changes in PVR (r=-0.29 (95% CI -0.41 to -0.17); p<0.0001) and cardiac index (r=0.23 (95% CI 0.10 to 0.35); p=0.0004).

CONCLUSIONS

Riociguat improved haemodynamics in patients with inoperable CTEPH or persistent/recurrent CTEPH.

TRIAL REGISTRATION NUMBER

NCT00855465.

Medical management of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) results from incomplete resolution of acute pulmonary emboli, organised into fibrotic material that obstructs large pulmonary arteries, and distal small-vessel arteriopathy. Pulmonary endarterectomy (PEA) is the treatment of choice for eligible patients with CTEPH; in expert centres, PEA has low in-hospital mortality rates and excellent long-term survival. Supportive medical therapy consists of lifelong anticoagulation plus diuretics and oxygen, as needed.

An important recent advance in medical therapy for CTEPH is the arrival of medical therapies for patients with inoperable disease or persistent/recurrent pulmonary hypertension after PEA. The soluble guanylate cyclase stimulator riociguat is licensed for the treatment of CTEPH in patients with inoperable disease or with recurrent/persistent pulmonary hypertension after PEA. Clinical trials of this agent have shown improvements in patients' haemodynamics and exercise capacity. Phosphodiesterase-5 inhibitors, endothelin receptor antagonists and prostanoids have been used in the treatment of CTEPH, but evidence of benefit is limited. Challenges in the future development of medical therapy for CTEPH include better understanding of the underlying pathology, end-points to monitor the condition's progress, and the optimisation of pulmonary arterial hypertension therapies in relation to diverse patient characteristics and emerging options such as balloon pulmonary angioplasty.

[Pulmonary hypertension : What is new in therapy?]

Pulmonary hypertension (PH) comprises a group of pulmonary vascular diseases that are characterized by progressive exertional dyspnea and right heart insufficiency ultimately resulting in right heart decompensation. The classification is into five clinical subgroups that form the absolutely essential basis for decisions on the indications for different pharmacological and non-pharmacological forms of treatment. The guidelines were updated in 2015 and in addition to the hitherto existing pharmacological treatment options of phosphodiesterase type 5 inhibitors, endothelin receptor antagonists and prostacyclins, the soluble guanylate cyclase stimulator riociguat has now been incorporated for treatment of certain forms of PH. This article provides an overview of the new treatment recommendations in the current guidelines, e. g. for PH patients who are in intensive care units due to surgical interventions or progressive right heart insufficiency.

[Clinical guidelines for the diagnosis and treatment of chronic thromboembolic pulmonary hypertension (Part 2)]

The paper gives current approaches to treating chronic thromboembolic pulmonary hypertension (CTEPH) from the document «Federal Guidelines for the Diagnosis and Treatment of CTEPH» approved at the Third Russian Congress on Pulmonary Hypertension on December 11, 2015. The guidelines had been elaborated to optimize the treatment of patients with CTEPH on the basis of an analysis of the data of the present-day registries and multicenter randomized clinical trials, national and international guidelines and consensus documents, and documents published in recent years. CTEPH is a unique form of pulmonary hypertension since it is potentially curable by surgical treatment. The paper presents indications for and contraindications to pulmonary thromboendartectomy; preparation for surgery; operating room facilities; the specific features of postoperative management and possible complications; and long-term RESULTS: In terms of therapy, in addition to non-pharmacological measures, the authors discuss maintenance and specific treatment options for CTEPH, balloon pulmonary angioplasty, and lung/heart-lung transplantation. In conclusion they propose a management algorithm in patients with CTEPH and requirements for its problem to the center of experts.

Medical Therapy Versus Balloon Angioplasty for CTEPH: A Systematic Review and Meta-Analysis

BACKGROUND

A significant number of chronic thromboembolic pulmonary hypertension (CTEPH) patients will have an inoperable disease. Medical therapy and balloon pulmonary angioplasty (BPA) have provided alternate therapeutic options for patients with inoperable CTEPH, although there are a limited number of published studies examining the outcomes. Thus, our study aims to evaluate and compare the efficacy of medical therapy and BPA in patients with inoperable CTEPH.

METHODS

An electronic search of six databases was performed and the search results were screened against established criteria for inclusion into this study. Data was extracted and meta-analytical techniques were used to analyse the data.

RESULTS

Pooled data from RCTs revealed that medical therapy, compared with a placebo, was associated with a significant improvement of at least one functional class (p=0.038). With regards to pulmonary haemodynamics, medical therapy also resulted in a significant reduction in both mean pulmonary arterial pressure (mPAP) (p=0.002) and pulmonary vascular resistance (PVR) (p<0.001). From the included observational studies, the 6-minute walk distance (6MWD) significantly increased following medical therapy by an average of 22.8% (p<0.001). The pooled improvement in 6MWD was found to be significantly higher in the BPA group when compared to medical therapy for CTEPH (p=0.001). Pooled data from available observational studies of medical therapy or BPA all demonstrated significant improvements in mPAP and PVR for pre versus post intervention comparisons. The improvement in mPAP (p=0.002) and PVR (p=0.002) were significantly greater for BPA intervention when compared to medical therapy.

CONCLUSIONS

High-quality evidence supports the use of targeted medical therapy in improving haemodynamics in patients with inoperable CTEPH. There is only moderate-quality evidence from observational studies supporting the efficacy of BPA in improving both haemodynamics and exercise capacity. Further RCTs and prospective observational studies comparing medical therapy and BPA in patients with inoperable CTEPH are required.

[Balloon pulmonary angioplasty: An additional treatment option to improve the status of patients with chronic thromboembolic pulmonary hypertension]

In chronic thromboembolic pulmonary hypertension (CTEPH), stenoses or obstructions of the pulmonary arteries due to organized thrombi can cause an elevation in pulmonary artery resistance, which in turn can result in pulmonary hypertension and progressive right heart failure. CTEPH can be cured surgically by pulmonary endarterectomy (PEA); however, patients deemed unsuitable for PEA due to distal lesion, advanced age, or comorbidities have a poor prognosis and limited treatment options. Recently, an alternative interventional strategy of balloon pulmonary angioplasty (BPA) reduces pulmonary artery hypertension in patients with CTEPH. Risk/benefit inbalance appear to be safe in experimented center. BPA can treat the lesions from lobar to subsegmental pulmonary arteries, improving functional and hemodynamic status for inoperable patients. This review highlights this recent progress.

Comparative efficacy and acceptability of endothelin receptor antagonists for pulmonary arterial hypertension: A network meta-analysis

BACKGROUND

Endothelin receptor antagonists (ERAs) such as ambrisentan, sitaxsentan, bosentan and macitentan are primary drug therapies for pulmonary arterial hypertension (PAH) patients. However, the optimal drugs for PAH remained controversial due to heterogeneous nature of randomized control trials (RCTs).

METHODS

Apart from traditional meta-analysis, network meta-analysis (NMA) was performed in this study for multiple comparisons among PAH therapies. The 6 minute walking distance (6MWD) and clinical worsening were efficacy outcomes whereas serious adverse effects (SAE) and all-cause discontinuation were acceptability outcomes. The weighted mean difference (WMD) and odds ratio (OR) along with their 95% confidence interval (95% CI) or 95% credible interval (95% CrI) were used to evaluate the positive and negative effects of these therapies on PAH patients.

RESULTS

By synthesizing direct evidence from 10 studies with a total number of 2172 patients, we discovered that all of the four PAH therapies significantly increased the average 6MWD in comparison to the placebo (P-value<0.05). Moreover, bosentan and ambrisentan both showed significant association with a decrease in the risk of clinical worsening compared to placebo. Regarding of all-cause discontinuation, ambrisentan is the only therapy which was significantly associated with a risk decrease compared to placebo. However, there was no sufficient evidence suggesting significant difference in any efficacy or acceptability outcomes between any two of the PAH therapies (P-value>0.05).

CONCLUSION

Ambrisentan could be considered as the most appropriate therapy among the four ERAs for PAH patients. Bosentan also behaved well, but it is not as safe as ambrisentan.

Association of oral endothelin receptor antagonists with risks of cardiovascular events and mortality: meta-analysis of randomized controlled trials

BACKGROUND

Endothelin receptor antagonists (ERAs) are widely used in a variety of disorders, including pulmonary artery hypertension, systemic sclerosis, diabetic and kidney diseases, and several tumors. However, reported adverse events, especially increased risks of cardiovascular disease (CVD) morbidity and mortality, have cast doubt on their potential clinical application. Therefore, we conducted this meta-analysis to confirm whether ERAs increased CVD risk and mortality.

METHODS

We systematically searched PubMed (1966-2015), EMBASE (1974-2015), ClinicalTrials.gov, and the Cochrane Controlled Clinical Trials Register Database for randomized controlled trials published between Jan 1, 1990 and Mar 18, 2015. Inclusion criteria included a study duration of more than 3 weeks, the use of a randomized control group receiving an oral ERA or placebo, and the availability of outcome data for cardiovascular events and all-cause death.

RESULTS

A total of 33 trials met the inclusion criteria. There were 8098 cases in the ERA group and 5074 cases in the placebo group. Compared with the control group, the risk ratio (RR) for all-cause death in the ERA group was 0.983 [95% confidence interval (CI), 0.883 to 1.094, P = 0.754]. The summary RR for cardiovascular events was 1.651 in the ERA group (95% CI, 1.164 to 2.34, P = 0.005). The pooled results showed that ERAs treatment could lead to more edema, anemia, and abnormal transaminase levels. Also, there was an increased proportion of discontinued therapy in the ERA treatment because of side effects (RR = 1.322, 95% CI, 1.036 to 1.686, P = 0.025). There were no significant differences in the experienced episodes of headache and dyspnea between the active therapy and control groups.

CONCLUSIONS

ERAs therapy is not significantly associated with increased all-cause death, but there are more cardiovascular events and edema or fluid retention, anemia, and liver enzymes disorder. Large clinical randomized controlled studies are needed to further confirm the safety of the clinical application of ERAs.

Reliable and developmentally appropriate study end points are needed to achieve drug development for treatment of pediatric pulmonary arterial hypertension

OBJECTIVE

To identify suitable end points and surrogates for pediatric pulmonary arterial hypertension (PAH) as the lack of developmentally appropriate end point and clinical trials contribute to the unmet medical need.

STUDY DESIGN

Reviewed the efficacy end points and surrogates for all trials (1995 to 2013) that were submitted to the Food and Drug Administration (FDA) to support the approval of PAH therapy and conducted literature search.

RESULTS

An increase in the 6 min walking distance (6MWD) was used as a primary end point in 8/9 adult PAH trials. This end point is not suitable for infants and young children because of performance limitations and lack of control data. One adult PAH trial used time to the first morbidity or mortality event as a primary end point, which could potentially be used in pediatric PAH trials. In the sildenafil pediatric PAH trial, the change in pulmonary vascular resistance index or mean pulmonary artery pressure was used as a surrogate for the 6MWD to assess exercise capacity. However, two deaths and three severe adverse events during the catheterizations made this an unacceptably high-risk surrogate. The INOmax persistent pulmonary hypertension of the newborn trial used a reduction in initiation of extracorporeal membrane oxygenation treatment as a primary end point, which is not feasible for other pediatric PAH trials. A Literature review revealed none of the existing noninvasive markers are fully validated as surrogates to assess PAH efficacy and long-term safety.

CONCLUSIONS

For pediatric PAH trials, clinical end points are acceptable, and novel validated surrogates would be helpful. FDA seeks collaboration with academia, industry and parents to develop other suitable and possibly more efficient efficacy end points to facilitate pediatric PAH drug development.

An Update on the Management of Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare but life-threatening form of pulmonary artery hypertension that is defined as a mean arterial pulmonary pressure greater than 25mmHg that persists for more than 6 months following anticoagulation therapy in the setting of pulmonary emboli. CTEPH is categorized by the World Health Organization as group IV pulmonary hypertension and is thought to be due to unresolved thromboemboli in the pulmonary artery circulation. Among the 5 classes of pulmonary hypertension, CTEPH is unique in that it is potentially curable with the use of pulmonary thromboendarterectomy surgery. Despite an increasing array of medical and surgical treatment options for patients with CTEPH over the past 2 decades, patients commonly present with advanced disease and carry a poor prognosis, thus, the need for early diagnosis and appropriate referral to an expert center. This review article first highlights the epidemiology, pathophysiology, and clinical presentation of CTEPH. The article then provides diagnostic and therapeutic algorithms for the management of the patient with suspected CTEPH.

Clinical Adverse Effects of Endothelin Receptor Antagonists: Insights From the Meta-Analysis of 4894 Patients From 24 Randomized Double-Blind Placebo-Controlled Clinical Trials

BACKGROUND

Evidence of the clinical safety of endothelin receptor antagonists (ERAs) is limited and derived mainly from individual trials; therefore, we conducted a meta-analysis.

METHODS AND RESULTS

After systematic searches of the Medline, Embase, and Cochrane Library databases and the ClinicalTrials.gov website, randomized controlled trials with patients receiving ERAs (bosentan, macitentan, or ambrisentan) in at least 1 treatment group were included. All reported adverse events of ERAs were evaluated. Summary relative risks and 95% CIs were calculated using random- or fixed-effects models according to between-study heterogeneity. In total, 24 randomized trials including 4894 patients met the inclusion criteria. Meta-analysis showed that the incidence of abnormal liver function (7.91% versus 2.84%; risk ratio [RR] 2.38, 95% CI 1.36-4.18), peripheral edema (14.36% versus 9.68%; RR 1.44, 95% CI 1.20-1.74), and anemia (6.23% versus 2.44%; RR 2.69, 95% CI 1.78-4.07) was significantly higher in the ERA group compared with placebo. In comparisons of individual ERAs with placebo, bosentan (RR 3.78, 95% CI 2.42-5.91) but not macitentan (RR 1.17, 95% CI 0.42-3.31) significantly increased the risk of abnormal liver function, whereas ambrisentan (RR 0.06, 95% CI 0.01-0.45) significantly decreased that risk. Bosentan (RR 1.47, 95% CI 1.06-2.03) and ambrisentan (RR 2.02, 95% CI 1.40-2.91) but not macitentan (RR 1.08, 95% CI 0.81-1.46) significantly increased the risk of peripheral edema. Bosentan (RR 3.09, 95% CI 1.52-6.30) and macitentan (RR 2.63, 95% CI 1.54-4.47) but not ambrisentan (RR 1.30, 95% CI 0.20-8.48) significantly increased the risk of anemia. ERAs were not found to increase other reported adverse events compared with placebo.

CONCLUSIONS

The present meta-analysis showed that the main adverse effects of treatment with ERAs were hepatic transaminitis (bosentan), peripheral edema (bosentan and ambrisentan), and anemia (bosentan and macitentan).

Pulmonary endarterectomy in the elderly: safety, efficacy and risk factors

AIMS

Pulmonary endarterectomy (PEA) is the treatment of choice for patients with chronic thromboembolic pulmonary hypertension, but there are few data in the literature about the results of this procedure in the elderly. In this study, we aimed to assess whether this type of surgery is effective and well tolerated for the elderly.

METHODS

A total of 264 consecutive patients who underwent PEA between January 2008 and December 2012 were reviewed. PEA was performed under cardiopulmonary bypass and hypothermic ventricular fibrillation, with the aorta left unclamped. The population was dichotomized according to age into the following two groups: below 70 years (n = 176, younger patients) and at least 70-year-olds (n = 88, elderly patients). Regression models were used to identify predictors of hospital mortality and postoperative adverse events, and their interaction with age was tested.

RESULTS

Hospital mortality was slightly, but not significantly higher in elderly patients (9.1 vs. 5.1%; P = 0.22). Effect modification by history of smoking and preoperative O2 therapy was present. The cumulative survival at 1, 2, and 4 years was 93, 92, and 91% among younger patients; and 88, 86, and 86% among older patients (P = 0.19). Clinical and hemodynamic improvement was similar in the two groups.

CONCLUSION

Despite a slightly higher short-term mortality, PEA is feasible and well tolerated for the vast majority of the elderly patients. Clinical and hemodynamic improvements are outstanding, with satisfactory long-term survival rates.

Severe Pulmonary Arteriopathy Is Associated with Persistent Hypoxemia after Pulmonary Endarterectomy in Chronic Thromboembolic Pulmonary Hypertension

BACKGROUND

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by occlusion of pulmonary arteries by organized chronic thrombi. Persistent hypoxemia and residual pulmonary hypertension (PH) following successful pulmonary endarterectomy (PEA) are clinically important problems; however, the underlying mechanisms remain unclear. We have previously reported that residual PH is closely related to severe pulmonary vascular remodeling and hypothesize that this arteriopathy might also be involved in impaired gas exchange. The purpose of this study was to evaluate the association between hypoxemia and pulmonary arteriopathy after PEA.

METHODS AND RESULTS

Between December 2011 and November 2014, 23 CTEPH patients underwent PEA and lung biopsy. The extent of pulmonary arteriopathy was quantified pathologically in lung biopsy specimens. We then analyzed the relationship between the severity of pulmonary arteriopathy and gas exchange after PEA. We observed that the severity of pulmonary arteriopathy was negatively correlated with postoperative and follow-up PaO2 (postoperative PaO2: r = -0.73, p = 0.0004; follow-up PaO2: r = -0.66, p = 0.001), but not with preoperative PaO2 (r = -0.373, p = 0.08). Multivariate analysis revealed that the obstruction ratio and patient age were determinants of PaO2 one month after PEA (R2 = 0.651, p = 0.00009). Furthermore, the obstruction ratio and improvement of pulmonary vascular resistance were determinants of PaO2 at follow-up (R2 = 0.545, p = 0.0002). Severe pulmonary arteriopathy might increase the alveolar-arterial oxygen difference and impair diffusion capacity, resulting in hypoxemia following PEA.

CONCLUSION

The severity of pulmonary arteriopathy was closely associated with postoperative and follow-up hypoxemia.

Endothelin ETA receptors predominate in chronic thromboembolic pulmonary hypertension

AIMS

Endothelin-1 levels are raised in chronic thromboembolic pulmonary hypertension. Our aim in this study was to identify the presence of endothelin receptors in patients with CTEPH by analysing tissue removed at pulmonary endarterectomy.

MAIN METHODS

Pulmonary endarterectomy tissue cross-sections were analysed using autoradiography with [(125)I]-ET-1 using ligands selective for ETA or ETB to determine sub-type distribution. The precise cellular localisation of ETA and ETB receptors was determined using selective antisera to both sub-types and compared with haematoxylin and eosin, Elastic Van Gieson and smooth muscle actin labelled sections.

KEY FINDINGS

Two patterns of ET-1 binding were found. In sections with frequent recanalised channels, ET-1 bound to the smooth muscle cells surrounding the channels. In sections where there was less organised thrombus with no obvious re-canalisation, minimal ET-1 binding was observed. Some contractile type smooth muscle cells not associated with recanalised channels and diffusely spread throughout the PEA material were associated with ET receptor antibody binding on immunohistochemistry. There was a greater expression of the ETA receptor type in the specimens.

SIGNIFICANCE

The presence of ET-1 receptors in the chronic thrombus in proximal CTEPH suggests ET-1 could act not only on the distal vasculopathy in the unobstructed vessels but may also stimulate smooth muscle cell proliferation within chronic clot. The abundance of ET receptors within the tissue provides evidence that the ET pathway is involved in the pathology of chronic thrombus reorganisation leading to CTEPH providing a rationale for the repurposing of ET receptor antagonists in the treatment of this condition.

Guanylate cyclase stimulators for pulmonary hypertension

BACKGROUND

Pulmonary hypertension is a condition of complex aetiology that culminates in right heart failure and early death. Soluble guanylate cyclase (sGC) stimulators are a promising class of agents that have recently gained approval for use.

OBJECTIVES

To evaluate the efficacy of sGC stimulators in pulmonary hypertension.

SEARCH METHODS

We searched CENTRAL (Cochrane Central Register of Controlled Trials), MEDLINE, EMBASE and the reference lists of articles. Searches are current as of 12 February 2016.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) involving participants with pulmonary hypertension of all ages, severities and durations of treatment.

DATA COLLECTION AND ANALYSIS

AW, MS and RW independently selected studies, assessed evidence quality and extracted data. This process was overseen by RT and SG. All included studies were sponsored by the drug manufacturer.

MAIN RESULTS

Five trials involving 962 participants are included in this review. All trials were of relatively short duration (< 16 weeks). Due to the heterogenous aetiology of pulmonary hypertension in participants, results are best considered according to each pulmonary hypertension subtype.Pooled analysis shows a mean difference (MD) increase in six-minute walking distance (6MWD) of 30.13 metres (95% CI 5.29 to 54.96; participants = 659; studies = 3). On subgroup analysis, for pulmonary arterial hypertension (PAH) there was no effect noted (6MWD; MD 11.91 metres, 95% CI -44.92 to 68.75; participants = 398; studies = 2), and in chronic thromboembolic pulmonary hypertension (CTEPH) sGC stimulators improved 6MWD by an MD of 45 metres (95% CI 23.87 to 66.13; participants = 261; studies = 1). Data for left heart disease-associated PH was not available for pooling. Importantly, when participants receiving phosphodiesterase inhibitors were excluded, sGC stimulators increased 6MWD by a MD of 36 metres in PAH. The second primary outcome, mortality, showed no change on pooled analysis against placebo (Peto odds ratio (OR) 0.57, 95% CI 0.18 to 1.80).Pooled secondary outcomes include an increase in World Health Organization (WHO) functional class (OR 1.53, 95% CI 0.87 to 2.72; participants = 858; studies = 4), no effect on clinical worsening (OR 0.45, 95% CI 0.17 to 1.14; participants = 842; studies = 3), and a reduction in mean pulmonary artery pressure (MD -2.77 mmHg, 95% CI -4.96 to -0.58; participants = 744; studies = 5). There was no significant difference in serious adverse events on pooled analysis (OR 1.12, 95% CI 0.66 to 1.90; participants = 818; studies = 5) or when analysed at PAH (MD -3.50, 95% CI -5.54 to -1.46; participants = 344; studies = 1), left heart disease associated subgroups (OR 1.56, 95% CI 0.78 to 3.13; participants = 159; studies = 2) or CTEPH subgroups (OR 1.29, 95% CI 0.65 to 2.56; participants = 261; studies = 1).It is important to consider the results for PAH in the context of a person who is not also receiving a phosphodiesterase-V inhibitor, a contra-indication to sGC stimulator use. It should also be noted that CTEPH results are applicable to inoperable or recurrent CTEPH only.Evidence was rated according to the GRADE scoring system. One outcome was considered high quality, two were moderate, and eight were of low or very low quality, meaning that for many of the outcomes the true effect could differ substantially from our estimate. There were only minor concerns regarding the risk of bias in these trials, all being RCTs largely following the original protocol. Most trials employed an intention-to-treat analysis.

AUTHORS' CONCLUSIONS

sGC stimulators improve pulmonary artery pressures in people with PAH (who are treatment naive or receiving a prostanoid or endothelin antagonist) or those with recurrent or inoperable CTEPH. In these settings this can be achieved without notable complication. However, sGC stimulators should not be taken by people also receiving phosphodiestase-V inhibitors or nitrates due to the risks of hypotension, and there is currently no evidence supporting their use in pulmonary hypertension associated with left heart disease. There is no evidence supporting their use in children. These conclusions are based on data with limitations, including unavailable data from two of the trials.

Group 5 Pulmonary Hypertension: The Orphan's Orphan Disease

Pulmonary hypertension is a complex disorder with multiple etiologies; the World Health Organization classification system divides pulmonary hypertension patients into 5 groups based on the underlying cause and mechanism. Group 5 pulmonary hypertension is a heterogeneous group of diseases that encompasses pulmonary hypertension secondary to multifactorial mechanisms. For many of the diseases, the true incidence, etiology, and treatment remain uncertain. This article reviews the epidemiology, pathogenesis, and management of many of the group 5 pulmonary hypertension disease states.

Exercise physiological responses to drug treatments in chronic thromboembolic pulmonary hypertension

We tested the hypothesis that patients with chronic thromboembolic pulmonary hypertension (CTEPH) that was deemed to be inoperable were more likely to respond to drugs for treating pulmonary arterial hypertension (PAH) by using cardiopulmonary exercise (CPX) testing than those with CTEPH that was deemed to be operable. We analyzed CPX testing data of all patients with CTEPH who were treated with PAH drugs and had undergone CPX testing before and after treatment at a single pulmonary hypertension center between February 2009 and March 2013. Suitability for pulmonary endarterectomy (PEA) was decided by experts in PEA who were associated with a treatment center. The group with inoperable CTEPH included 16 patients, the operable group included 26 patients. There were no differences in demographics and baseline hemodynamic data between the groups. Unlike patients in the operable group, after drug treatment patients with inoperable CTEPH had a significantly higher peak V̇o2 (P < 0.001), work load (P = 0.002), and oxygen pulse (P < 0.001). In terms of gas exchange, there was an overall net trend toward improved V̇e/V̇co2 in the group with inoperable CTEPH, with an increased PaCO2 (P = 0.01), suggesting reduced hyperventilation. No changes were observed in patients with operable CTEPH. In conclusion, treatment with PAH drug therapy reveals important pathophysiological differences between inoperable and operable CTEPH, with significant pulmonary vascular and cardiac responses in inoperable disease. Drug effects on exercise function observed in inoperable CTEPH cannot be translated to all forms of CTEPH.

The Endothelium-Dependent Nitric Oxide-cGMP Pathway

Nitric oxide (NO)-cyclic 3'-5' guanosine monophosphate (cGMP) signaling plays a critical role on smooth muscle tone, platelet activity, cardiac contractility, renal function and fluid balance, and cell growth. Studies of the 1990s established endothelium dysfunction as one of the major causes of cardiovascular diseases. Therapeutic strategies that benefit NO bioavailability have been applied in clinical medicine extensively. Basic and clinical studies of cGMP regulation through activation of soluble guanylyl cyclase (sGC) or inhibition of cyclic nucleotide phosphodiesterase type 5 (PDE5) have resulted in effective therapies for pulmonary hypertension, erectile dysfunction, and more recently benign prostatic hyperplasia. This section reviews (1) how endothelial dysfunction and NO deficiency lead to cardiovascular diseases, (2) how soluble cGMP regulation leads to beneficial effects on disorders of the circulation system, and (3) the epigenetic regulation of NO-sGC pathway components in the cardiovascular system. In conclusion, the discovery of the NO-cGMP pathway revolutionized the comprehension of pathophysiological mechanisms involved in cardiovascular and other diseases. However, considering the expression "from bench to bedside" the therapeutic alternatives targeting NO-cGMP did not immediately follow the marked biochemical and pathophysiological revolution. Some therapeutic options have been effective and released on the market for pulmonary hypertension and erectile dysfunction such as inhaled NO, PDE5 inhibitors, and recently sGC stimulators. The therapeutic armamentarium for many other disorders is expected in the near future. There are currently numerous active basic and clinical research programs in universities and industries attempting to develop novel therapies for many diseases and medical applications.

Treatment of patients with chronic thrombo embolic pulmonary hypertension: focus on riociguat

Chronic thromboembolic pulmonary hypertension (CTEPH) is a disease of the pulmonary vascular bed that is characterized by elevations in the mean pulmonary artery pressure in the setting of perfusion defects on ventilation–perfusion scan, and subsequently confirmed by pulmonary angiography. CTEPH, or World Health Organization (WHO) group 4 pulmonary hypertension, is a result of unresolved thromboembolic obstruction in the pulmonary arteries. Pulmonary endarterectomy (PEA) is the treatment of choice for CTEPH as it is a potentially curative therapy. However, up to one-third of patients are not candidates for the surgery, either due to distal and inaccessible nature of the lesions or comorbid conditions. Due to remodeling that occurs in nonobstructed pulmonary vessels, a portion of patients who have undergone PEA have residual CTEPH after the procedure, attributable to high shear stress prior to PEA. This phenomenon has led to the understanding of a so-called “two-compartment model” of CTEPH, opening the door to pharmacologic treatment strategies. In 2013, riociguat, a soluble guanylate cyclase stimulator, was approved in the US and Europe for the treatment of inoperable or persistent/recurrent CTEPH. This article reviews the current management of CTEPH with a focus on riociguat.

Effects of bosentan on peripheral endothelial function in patients with pulmonary arterial hypertension or chronic thromboembolic pulmonary hypertension

Endothelin receptor antagonists (ERAs) have been shown to improve the prognosis of patients with pulmonary arterial hypertension (PAH). However, the effect of the oral dual ERA bosentan on peripheral endothelial dysfunction (PED), as assessed by flow-mediated vasodilation (FMD), in patients with pulmonary hypertension is not well characterized. We investigated the effect of bosentan on PED in patients with PAH or inoperable chronic thromboembolic pulmonary hypertension (CTEPH). A total of 18 patients with PAH and 8 with CTEPH were treated with bosentan. All patients underwent FMD assessment before and after 3 months of bosentan treatment. Whereas FMD increased from 6.01% ± 2.42% at baseline to 8.07% ± 3.18% after 3 months (P < 0.0001) in patients with PAH, those with CTEPH showed no change in FMD after bosentan therapy. In addition, FMD at baseline showed no correlation with pulmonary vascular resistance (r = 0.09) or plasma brain natriuretic peptide levels (r = -0.23) in patients with PAH. Bosentan treatment ameliorated PED in patients with PAH but not in those with inoperable CTEPH. In addition, FMD did not correlate with PAH severity.

Riociguat for pulmonary hypertension

Riociguat is newly approved by the FDA for treatment of patients with groups 1 or 4 pulmonary hypertension. Although several vasodilators are on the market for the treatment of pulmonary hypertension group 1, none have been shown to be invariably effective in the treatment of chronic thromboembolic pulmonary hypertension.

Riociguat for the treatment of pulmonary hypertension: Chinese subgroup analyses and comparison

OBJECTIVE

PATENT-1 and CHEST-1 were pivotal, international phase III trials assessing riociguat for pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Here we compare Chinese patients from these studies with the overall populations, and report the clinical effect and safety of riociguat in Chinese patients with PAH and CTEPH.

METHODS

PATENT-1 was a 12-week, randomised, double-blind, placebo-controlled trial of riociguat (maximum 2.5 mg three times daily or 1.5 mg three times daily (exploratory) in patients with PAH. CHEST-1 was a 16-week, randomised, double-blind, placebo-controlled trial of riociguat (maximum 2.5 mg three times daily) in patients with inoperable CTEPH or persistent/recurrent pulmonary hypertension after pulmonary endarterectomy. The primary endpoint in each study was change from baseline to study end in 6 min walking distance (6MWD). Secondary endpoints included pulmonary vascular resistance (PVR), N-terminal prohormone of brain natriuretic peptide, WHO functional class (FC), and time to clinical worsening.

RESULTS

Chinese patients in PATENT-1 (n=77) and CHEST-1 (n=32) were younger and had better baseline 6MWD and WHO FC versus the overall population. Riociguat increased 6MWD versus placebo in Chinese patients in PATENT-1 and CHEST-1, with a greater increase observed in CHEST-1 (least-squares mean differences +46 m and +102 m in PATENT-1 and CHEST-1, respectively). Riociguat also improved several secondary endpoints in both studies, and was well tolerated.

CONCLUSIONS

Chinese patients displayed differences in baseline characteristics versus the overall populations in PATENT-1 and CHEST-1. Riociguat improved 6MWD, PVR, WHO FC, and other clinical outcomes in Chinese patients with PAH or CTEPH.

TRIAL REGISTRATION NUMBER

PATENT-1: NCT00810693, Results; CHEST-1 NCT00855465, Results.