French experience of balloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension

Exercise hyperventilation and pulmonary gas exchange in chronic thromboembolic pulmonary hypertension: Effects of balloon pulmonary angioplasty

BACKGROUND

Excessive ventilation (V̇E) and abnormal gas exchange during exercise are features of chronic thromboembolic pulmonary hypertension (CTEPH). In selected CTEPH patients, balloon pulmonary angioplasty (BPA) improves symptoms and exercise capacity. How BPA affects exercise hyperventilation and gas exchange is poorly understood.

METHODS

In this longitudinal observational study, symptom-limited cardiopulmonary exercise tests and carbon monoxide lung diffusion (DLCO) were performed before and after BPA (interval, mean (SD): 3.1 (2.4) months) in 36 CTEPH patients without significant cardiac and/or pulmonary comorbidities.

RESULTS

Peak work rate improved by 20% after BPA whilst V̇E at peak did not change despite improved ventilatory efficiency (lower V̇E with respect to CO₂ output [V̇CO₂]). At the highest identical work rate pre- and post-BPA (75 (30) watts), V̇E and alveolar-arterial oxygen gradient (P(Ai-a)O₂) decreased by 17% and 19% after BPA, respectively. The physiological dead space fraction of tidal volume (VD/VT), calculated from measurements of arterial and mixed expired CO₂, decreased by 20%. In the meantime, DLCO did not change. The best correlates of P(Ai-a)O₂ measured at peak exercise were physiological VD/VT before BPA and DLCO after BPA.

CONCLUSIONS

Ventilatory efficiency, physiological VD/VT, and pulmonary gas exchange improved after BPA. The fact that DLCO did not change suggests that the pulmonary capillary blood volume and probably the true alveolar dead space were unaffected by BPA. The correlation between DLCO measured before BPA and P(Ai-a)O₂ measured after BPA suggests that DLCO may provide an easily accessible marker to predict the response to BPA in terms of pulmonary gas exchange.

Characteristics and in-hospital outcomes of patients undergoing balloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension: a time-trend analysis from the Japanese nationwide registry

BACKGROUND

Balloon pulmonary angioplasty (BPA), a novel technique initially introduced as a treatment for inoperable chronic thromboembolic pulmonary hypertension, is now increasingly being performed in a broader spectrum of patients. Here, we performed a time-trend analysis of the characteristics and in-hospital outcomes of patients who underwent BPA in Japan, using data extracted from nationwide procedure-based registration system.

METHODS

The Japanese Structural Heart Disease (J-SHD) registry was established and sponsored by the Japanese Association of Cardiovascular Intervention and Therapeutics and aims to provide basic statistics on the performance of structural interventions in Japan. J-SHD registers cases from approximately 200 institutions, representing more than 90% of SHD intervention-performing hospitals in the nation. We analysed the registered BPA data elements from January 2015 to December 2018. Successful BPA was defined as a session in which a physician successfully treated all targeted lesions.

RESULTS

There were a total of 2512 BPA sessions; the number of institutions and registered sessions increased from 30 to 50 sites and from 479 to 852 sessions during the study period, respectively. The average age of the patients was 66±13 years, and 72.1% were women. In-hospital death was observed in 0.2%, and the total complications rate was 5.3%. The preoperative and postoperative mean pulmonary artery pressure were 32±11 mm Hg and 30±10 mm Hg, respectively.

CONCLUSION

The number of BPA sessions increased during the study period, with an acceptable in-hospital complication rate.

Balloon pulmonary angioplasty protocol in a Portuguese pulmonary hypertension expert center

INTRODUCTION

Balloon pulmonary angioplasty (BPA) has emerged as a promising therapeutic option for patients with chronic thromboembolic pulmonary hypertension (CTEPH) who are not eligible for pulmonary thromboendarterectomy (PEA) or who have recurrent or persistent pulmonary hypertension after surgery. There is no standardized technique for BPA and, its complexity and high risk of severe complications, requires skills and appropriate training and should be reserved for expert CTEPH centers, as a complementary intervention to medical and surgical therapy.

OBJECTIVE

The purpose of this document is to describe the BPA protocol used at a high-volume center nationwide, validated by its results.

METHODS

The present protocol includes technical details, definition of outcomes and complications, as well as patient full diagnostic work-up and treatment algorithm, before and after BPA.

RESULTS

The technical, hemodynamic, and clinical results of the application of this protocol will be subject of a later publication where they will be described in detail. In conclusion, we present a percutaneous intervention protocol in the treatment of pulmonary hypertension in the context of chronic pulmonary thromboembolism, validated by its clinical, hemodynamic, and technical results.

Evaluation and management of patients with chronic thromboembolic pulmonary hypertension - consensus statement from the ISHLT

ISHLT members have recognized the importance of a consensus statement on the evaluation and management of patients with chronic thromboembolic pulmonary hypertension. The creation of this document required multiple steps, including the engagement of the ISHLT councils, approval by the Standards and Guidelines Committee, identification and selection of experts in the field, and the development of 6 working groups. Each working group provided a separate section based on an extensive literature search. These sections were then coalesced into a single document that was circulated to all members of the working groups. Key points were summarized at the end of each section. Due to the limited number of comparative trials in this field, the document was written as a literature review with expert opinion rather than based on level of evidence.

Rescue balloon pulmonary angioplasty for life-threatening acute pulmonary embolism on chronic thromboembolic pulmonary hypertension patients

We report the cases of two patients with life-threatening acute pulmonary embolism (PE) on chronic thromboembolic pulmonary hypertension (CTEPH) who were treated with rescue balloon pulmonary angioplasty (BPA). These cases highlight the effect of rescue BPA on acute PE on CTEPH, which requires veno-arterial extracorporeal membrane oxygenation.

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Chronic thromboembolic pulmonary hypertension (CTEPH) is a fatal disease, which may deteriorate rapidly and require mechanical support.

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Rescue ballon pulmonary angioplasty (BPA) may be effective for diatal-type CTEPH patients requiring mechanical support.

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Rescue BPA should be consdered as an option in the absence of treatment for critical CTEPH patients.

Balloon pulmonary angioplasty protocol in a Portuguese pulmonary hypertension expert center

INTRODUCTION

Balloon pulmonary angioplasty (BPA) has emerged as a promising therapeutic option for patients with chronic thromboembolic pulmonary hypertension (CTEPH) who are not eligible for pulmonary thromboendarterectomy (PEA) or who have recurrent or persistent pulmonary hypertension after surgery. There is no standardized technique for BPA and, its complexity and high risk of severe complications, requires skills and appropriate training and should be reserved for expert CTEPH centers, as a complementary intervention to medical and surgical therapy.

OBJECTIVE

The purpose of this document is to describe the BPA protocol used at a high-volume center nationwide, validated by its results.

METHODS

The present protocol includes technical details, definition of outcomes and complications, as well as patient full diagnostic work-up and treatment algorithm, before and after BPA.

RESULTS

The technical, hemodynamic, and clinical results of the application of this protocol will be subject of a later publication where they will be described in detail. In conclusion, we present a percutaneous intervention protocol in the treatment of pulmonary hypertension in the context of chronic pulmonary thromboembolism, validated by its clinical, hemodynamic, and technical results.

Efficacy and Safety of Percutaneous Pulmonary Artery Subtotal Occlusion and Chronic Total Occlusion Intervention in Chronic Thromboembolic Pulmonary Hypertension

[Figure: see text].

What's new in pulmonary hypertension clinical research: lessons from the best abstracts at the 2020 American Thoracic Society International Conference

In this conference paper, we review the 2020 American Thoracic Society International Conference session titled, "What's New in Pulmonary Hypertension Clinical Research: Lessons from the Best Abstracts". This virtual mini-symposium took place on 21 October 2020, in lieu of the annual in-person ATS International Conference which was cancelled due to the COVID-19 pandemic. Seven clinical research abstracts were selected for presentation in the session, which encompassed five major themes: (1) standardizing diagnosis and management of pulmonary hypertension, (2) improving risk assessment in pulmonary arterial hypertension, (3) evaluating biomarkers of disease activity, (4) understanding metabolic dysregulation across the spectrum of pulmonary hypertension, and (5) advancing knowledge in chronic thromboembolic pulmonary hypertension. Focusing on these five thematic contexts, we review the current state of knowledge, summarize presented research abstracts, appraise their significance and limitations, and then discuss relevant future directions in pulmonary hypertension clinical research.

Balloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension: advances in patient and lesion selection

PURPOSE OF REVIEW

Balloon pulmonary angioplasty (BPA) has been performed worldwide for patients who are ineligible for pulmonary endarterectomy (PEA). However, the technical details of BPA have not been standardized, and no international consensus regarding patient and lesion selection for BPA has been reached. Evidence for the combination of BPA with PEA or medical therapy is also lacking. This review highlights recent progress in BPA in terms of patient and lesion selection and the current procedural approach for BPA, including combination treatment.

RECENT FINDINGS

The indications for BPA have expanded with recent reports describing the improved safety and efficacy of BPA. Because lesions are generally present in all segmental and subsegmental pulmonary arteries, it is recommended to treat all the lesions to achieve desirable hemodynamic improvement. Selective pulmonary angiography is the gold standard for lesion selection in modern BPA aimed at total revascularization. Despite the lack of randomized controlled studies, combination treatment with BPA may be well tolerated and effective.

SUMMARY

BPA, alone or in combination with PEA or medical therapy, may be a treatment option for patients who are not candidates for monotreatment of PEA. However, further investigation is required to standardize patient and lesion selection for BPA.

Safety and efficacy of balloon pulmonary angioplasty in a Portuguese pulmonary hypertension expert center

INTRODUCTION

Balloon pulmonary angioplasty (BPA) is an alternative therapy in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH) or residual/recurrent pulmonary hypertension (PH) after surgery. The aim of this study was to assess the short-term efficacy and safety of a BPA program.

METHODS

This prospective single-center study included all BPA sessions performed in CTEPH patients between 2017 and 2019. Clinical assessment including WHO functional class, plasma biomarkers, 6-min walk test (6MWT) and right heart catheterization was performed at baseline and six months after the last BPA session.

RESULTS

A total of 57 BPA sessions were performed in 11 CTEPH patients (64% with inoperable disease, 82% under pulmonary vasodilator therapy). Nine patients completed both the BPA program and a minimum six-month follow-up period. There were significant improvements in WHO functional class (p=0.004) and 6MWT (mean increase of 42 m; p=0.050) and a trend for significant hemodynamic improvement: 25% decrease in mean pulmonary artery pressure (mPAP) (p=0.082) and 42% decrease in pulmonary vascular resistance (PVR) (p=0.056). In the group of patients with severely impaired hemodynamics (three patients with mPAP >40mmHg), the reduction was significant: 51% in mPAP (p=0.013) and 67% in PVR (p=0.050). Prostacyclin analogs and long-term oxygen therapy were withdrawn in all patients. Minor complications were recorded in 25% of patients. There were no major complications or deaths.

CONCLUSIONS

A BPA strategy on top of pulmonary vasodilator therapy further improves symptoms, exercise capacity and hemodynamics with an acceptable risk-benefit ratio in patients with inoperable CTEPH or residual/recurrent PH after surgery.

ERS statement on chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare complication of acute pulmonary embolism, either symptomatic or not. The occlusion of proximal pulmonary arteries by fibrotic intravascular material, in combination with a secondary microvasculopathy of vessels <500 µm, leads to increased pulmonary vascular resistance and progressive right heart failure. The mechanism responsible for the transformation of red clots into fibrotic material remnants has not yet been elucidated. In patients with pulmonary hypertension, the diagnosis is suspected when a ventilation/perfusion lung scan shows mismatched perfusion defects, and confirmed by right heart catheterisation and vascular imaging. Today, in addition to lifelong anticoagulation, treatment modalities include surgery, angioplasty and medical treatment according to the localisation and characteristics of the lesions.This statement outlines a review of the literature and current practice concerning diagnosis and management of CTEPH. It covers the definitions, diagnosis, epidemiology, follow-up after acute pulmonary embolism, pathophysiology, treatment by pulmonary endarterectomy, balloon pulmonary angioplasty, drugs and their combination, rehabilitation and new lines of research in CTEPH.It represents the first collaboration of the European Respiratory Society, the International CTEPH Association and the European Reference Network-Lung in the pulmonary hypertension domain. The statement summarises current knowledge, but does not make formal recommendations for clinical practice.

Balloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a form of pulmonary hypertension (PH) caused by thromboembolic disease with the secondary remodeling of the pulmonary vessels. The primary treatment of CTEPH is pulmonary thromboendarterectomy (PTE). However, some patients are not candidates for PTE because of surgically inaccessible thrombi or high operative risk and can be candidates for balloon pulmonary angioplasty (BPA), an emerging, lower risk treatment. This review discusses the patient selection, the technique, and comprehensive review of reported outcomes following BPA. BPA techniques have improved over the years, and so has its safety profile. Recent data show that after several sessions of BPA, patients who were not eligible for PTE had improvement in their hemodynamic profile, functional capacity, and 6-minute walk distance. Studies have shown that compared to riociguat, BPA has shown significant improvement in the functional capacity and hemodynamic measurements. Reperfusion pulmonary edema is a common complication after PTE and BPA, which may be due to vessel injury rather than pulmonary extravasation. Rates of complications have decreased especially after the use of optical coherence tomography, which helps in proper sizing of the balloons. Patients with CTEPH who are ineligible for PTE should be evaluated for BPA. In addition to medical therapy, BPA has shown promising clinical and hemodynamic outcomes in patients with CTEPH.

Advances in balloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension

Balloon pulmonary angioplasty (BPA) is an emerging treatment option for patients with chronic thromboembolic pulmonary hypertension (CTEPH) who have inoperable, segmental/subsegmental disease, or residual disease after pulmonary endarterectomy. In the past decade, advances in the techniques for BPA have led to better clinical outcomes with improvements in hemodynamics, pulmonary perfusion, exercise tolerance, functional capacity, and quality of life. We present the experience with BPA at our university, the largest CTEPH center in the world, followed by reviewing the published data regarding the efficacy and safety of BPA in patients with CTEPH. There is increasing evidence to support that the initial hemodynamic improvement is sustained for ≥3 years after the procedure. Although infrequent, complications observed with BPA are associated with pulmonary vascular injury or rarely reperfusion pulmonary edema. As the technique for percutaneous pulmonary artery revascularization has improved, the procedural risk and complications have continued to decrease. This promising technique continues to develop, and future research is required to demonstrate the long-term benefits of BPA, standardize the technique, and define a uniform institutional infrastructure for providing BPA as a part of the treatment of CTEPH.

Treatment Strategy Options in Inoperable Chronic Thromboembolic Pulmonary Hypertension Patients

This review presents an analysis of recent publications on the principles of diagnosis and management of patients with chronic thromboembolic pulmonary hypertension (CTEPH). The authors emphasize the importance of patient's operability assessment regarding the possibility of performing pulmonary thrombendarterectomy - a radical treatment option due to complete post-thrombotic material removal from the branches of the pulmonary artery. In the case of an inoperable type of CTEPH, such a method of transcatheter treatment as step-by-step balloon angioplasty of the pulmonary artery (BPA) is proposed. The article clearly outlines the principles of selection, patient training and techniques for BPA. The authors demonstrated their own patented method of the peripheral vascular bed visualization in the case of recanalization of chronic occlusions, which increases the safety of this intervention. Particular attention is paid to hybrid approaches using a soluble guanylate cyclase stimulator, riociguate in combination with BPA for high risk CTEPH patients. The review presents the data of the post hoc analysis of the CHEST-1 study and the data of real clinical practice of the use of riociguat in combination with the endovascular method of treatment on the example of the leading expert groups in Europe, who demonstrated in their studies the positive effect of riociguat on the hemodynamic parameters and the frequency of perioperative complications.

Mid-term follow-up of balloon pulmonary angioplasty for inoperable chronic thromboembolic pulmonary hypertension: An experience in Latin America

OBJECTIVES

To describe the characteristics of patients who undergo balloon pulmonary angioplasty (BPA) for inoperable chronic thromboembolic pulmonary hypertension (CTEPH) and report the mid-term outcomes.

BACKGROUND

BPA has been recently introduced in Latin America. Mid-term results have not been published.

METHODS

Prospective Chilean Registry of inoperable CTEPH patients who underwent BPA. Clinical variables were analyzed at baseline, after each procedure and at follow-up. Hemodynamic variables were recorded before and after the last BPA.

RESULTS

Between August 2016 and September 2019, 22 patients (17 women), 59 ± 12.7 years, underwent 81 BPA and were followed for as long as 33.1 months (mean 17.3 ± 7.5). Mean pulmonary artery pressure decreased by 17.4% (51.1 ± 12 vs. 42.2 ± 13 mmHg, p = .001), pulmonary vascular resistance by 23.9% (766.7 ± 351 vs. 583 ± 346 dynes/s/cm^-5 , p = .001), cardiac index increased by 8% (2.3 ± 0.54 vs. 2.5 ± 0.54 L/min/m² , p = .012), N-terminal pro-B-type natriuretic peptide decreased by 73.8% (1,685 ± 1,045 vs. 441.8 ± 276 pg/dl, p = .006), and 6-min walk distance improved by 135 m (316.7 ± 94 vs. 451.1 ± 113 m, p = .001). One patient (4.5%) developed lung reperfusion injury and four patients (18.2%) had minor bleeding (hemoptysis), after the procedure. There was no mortality associated with BPA.

CONCLUSIONS

Our results confirm that BPA for inoperable CTEPH is a relatively safe procedure that improves clinical and hemodynamic parameters in the mid-term. This therapy should be considered as an alternative, mainly in places where access to PAH therapy or surgery is restricted.

Continual Improvement in Pressure Gradient at the Lesion After Balloon Pulmonary Angioplasty for Chronic Thromboembolic Pulmonary Hypertension

BACKGROUND

Lung injury is a serious complication of balloon pulmonary angioplasty (BPA) for chronic thromboembolic pulmonary hypertension (CTEPH). Selecting a smaller balloon might minimize the occurrence of lung injury; however, it could also increase the risk of restenosis.

METHODS

We analyzed the first target lesions in the initial BPA procedure in 34 consecutive patients with CTEPH. We measured proximal pressure with a guiding catheter and distal pressure with a pressure wire. We retrospectively investigated pressure gradients at the lesions before and immediately after the initial dilation with a smaller balloon and before the second procedure.

RESULTS

The proximal pressure decreased, and the distal pressure increased immediately after the initial balloon dilation. The pressure gradient at the lesion diminished significantly by the second procedure (from 26.4 ± 10.7 to 18.2 ± 9.9 mm Hg, P < 0.001) without serious complications. The residual pressure gradient had further diminished (to 9.8 ± 6.5 mm Hg, P = 0.02) until the second procedure. The reduction in pressure gradient at the lesion from immediately after the initial balloon dilation to the second procedure was positively correlated with both the baseline mean pulmonary arterial pressure (r² = 0.23, P = 0.004) and residual pressure gradient immediately after the initial balloon dilation (r² = 0.58, P < 0.001).

CONCLUSIONS

The residual pressure gradient at the lesion diminished continually after dilation with a smaller balloon. This strategy could decrease pulmonary arterial pressure safely. It would be reasonable to dilate the lesions sequentially in 2 procedures.

Assessment of oxygenation after balloon pulmonary angioplasty for patients with inoperable chronic thromboembolic pulmonary hypertension

BACKGROUND

The efficacy of balloon pulmonary angioplasty (BPA) in patients with inoperable chronic thromboembolic pulmonary hypertension would be promising. However, some patients showed residual dyspnea or symptoms, despite normalized hemodynamics. We aimed to clarify the clinical impact of oxygenation parameters on BPA outcome.

METHOD

Ninety-nine consecutive patients who underwent BPA from September 2011 to December 2019 were enrolled. We evaluated hemodynamics with right heart catheterization, arterial blood gas examination, New York Heart Association functional class (NYHA-FC), respiratory function tests, nocturnal oximetry, and exercise capacity (6-min walk test and cardiopulmonary exercise testing) at baseline and after BPA.

RESULT

Nearly normal hemodynamics was achieved after BPA (mean pulmonary artery pressure (PAP): 37.5 ± 10.0 to 20.6 ± 4.9 mmHg, p < 0.01). Oxygenation slightly improved (partial pressure of arterial oxygen; 61.5 ± 12.3 to 67.7 ± 12.7 mmHg, p < 0.01). Exertional desaturation remained unchanged (-8.1 ± 4.8 to -7.8 ± 5.1, p = 0.59), and this was associated with residual symptom (NYHA-FC ≥ 2) after BPA (OR 0.591, 95% CI 0.416-0.840, p = 0.003) in multivariate regression analyses. Lower vital capacity (r² = 0.03, p = 0.01), higher mean PAP (r² = 0.08, p = 0.02), and higher minute ventilation/carbon dioxide production (VE/VCO₂) slope (r² = 0.18, p < 0.01), the marker of ventilatory inefficiency, were correlated with exertional desaturation after BPA in multivariate linear analyses.

CONCLUSION

Although hemodynamics nearly normalized, oxygenation did not. Moreover, exertional desaturation remained unchanged. This might cause residual symptom after BPA. Residual pulmonary hypertension suggesting incurable arteriopathy, and higher VE/VCO₂ slope suggesting ventilation-perfusion mismatch might be related to exertional desaturation. Domiciliary oxygen therapy should be continued, if necessary.

Balloon Pulmonary Angioplasty: State of the Art

Balloon pulmonary angioplasty (BPA) is a novel technique for the treatment of chronic thromboembolic pulmonary hypertension. While cardiologists need no introduction to the concept of balloon angioplasty, BPA has its own particular challenges. This article aims to provide the reader with an overview of BPA, starting with an introduction to chronic thromboembolic disease (CTED), the standard management of chronic thromboembolic pulmonary hypertension (CTEPH), technical challenges faced when performing BPA and the evidence base supporting its use. The second part of the article will focus on the future of BPA, in particular the areas where research is required to establish an evidence base to justify the role of BPA in CTEPH and CTED treatment.

Balloon Pulmonary Angioplasty in Technically Operable and Technically Inoperable Chronic Thromboembolic Pulmonary Hypertension

Background: In this study, we aimed to assess the efficacy and safety of balloon pulmonary angioplasty (BPA) in patients with technically inoperable distal-type chronic thromboembolic pulmonary hypertension (d-CTEPH) and technically operable proximal-type disease (p-CTEPH) by analyzing the results of BPA treatment in two collaborating CTEPH referral centers. Methods and results: We assessed hemodynamic results, functional efficacy, complication and survival rate after BPA treatment in 70 CTEPH patients (median age 64 years; (interquartile range (IQR): 52–73 years)), of whom 16 (median age 73 years; (QR 62–82 years)) were in the p-CTEPH subgroup. Altogether, 377 BPA procedures were performed, resulting in significant (p < 0.001) improvement in mean pulmonary artery pressure (mPAP 48.6 ± 10 vs. 31.3 ± 8.6 mmHg), pulmonary vascular resistance (694 ± 296 vs. 333 ± 162 dynes*s*cm⁻⁵), six-minute walk test (365 ± 142 vs. 433 ± 120 metres) and N-terminal pro B-type natriuretic peptide (1307 (510–3294) vs. 206 (83–531) pg/mL). The rate of improvement did not differ between the sub-groups. Lung injury episodes and severe hemoptysis were similarly infrequent in d-CTEPH and p-CTEPH (6.4% vs. 5%; p = 0.55 and 1.0% vs. 2.5; p = 0.24, respectively). There was no significant difference between the sub-groups regarding survival (p = 0.53 by log-rank test). Conclusion: BPA may be beneficial in patients with p-CTEPH who cannot undergo pulmonary endarterectomy (PEA). Larger long-term studies are needed to better define the efficacy, safety, and optimal BPA procedural standards in this population.

Chronic Thromboembolic Pulmonary Hypertension: JACC Focus Seminar

Chronic thromboembolic pulmonary hypertension (CTEPH) is the result of pulmonary arterial obstruction by organized thrombotic material stemming from incompletely resolved acute pulmonary embolism. The exact incidence of CTEPH is unknown but appears to approximate 2.3% among survivors of acute pulmonary embolism. Although ventilation/perfusion scintigraphy has been supplanted by computed tomographic pulmonary angiography in the diagnostic approach to acute pulmonary embolism, it has a major role in the evaluation of patients with suspected CTEPH, the presence of mismatched segmental defects being consistent with the diagnosis. Diagnostic confirmation of CTEPH is provided by digital subtraction pulmonary angiography, preferably performed at a center familiar with the procedure and its interpretation. Operability assessment is then undertaken to determine if the patient is a candidate for potentially curative pulmonary endarterectomy surgery. When pulmonary endarterectomy is not an option, pulmonary arterial hypertension-targeted pharmacotherapy and balloon pulmonary angioplasty represent potential therapeutic alternatives.

Interventional and pharmacological management of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is caused by obstruction of the pulmonary vasculature, leading to increased pulmonary vascular resistance and ultimately right ventricular failure, the leading cause of death in non-operated patients. This article reviews the current management of CTEPH. The standard of care in CTEPH is pulmonary endarterectomy (PEA). However, up to 40% of patients with CTEPH are ineligible for PEA, and up to 51% develop persistent/recurrent PH after PEA. Riociguat is currently the only medical therapy licensed for treatment of inoperable or persistent/recurrent CTEPH after PEA based on the results of the Phase III CHEST-1 study. Studies of balloon pulmonary angioplasty (BPA) have shown benefits in patients with inoperable or persistent/recurrent CTEPH after PEA; however, data are lacking from large, prospective, controlled studies. Studies of macitentan in patients with inoperable CTEPH and treprostinil in patients with inoperable or persistent/recurrent CTEPH showed positive results. Combination therapy is under evaluation in CTEPH, and long-term data are not available. In the future, CTEPH may be managed by PEA, medical therapy or BPA - alone or in combination, according to individual patient needs. Patients should be referred to experienced centers capable of assessing and delivering all options.

Pulmonary angioplasty: A step further in the continuously changing landscape of chronic thromboembolic pulmonary hypertension management

Chronic thromboembolic pulmonary hypertension (CTEPH) is a potentially fatal and frequently undiagnosed form of pulmonary hypertension (PH), classified within group 4 by the World Health Organization (WHO). It is a type of precapillary PH, which uncommonly develops as a peculiar sequel of acute pulmonary embolism due to the partial resolution of the mechanically obstructing thrombus with a coexisting inflammatory response from pulmonary vessels. CTEPH is one of the potentially treatable forms of PH whose current standard of care is surgical pulmonary endarterectomy. Medical therapy with few drugs in non-operable disease is approved and has shown improvement in patients' hemodynamic condition and functional ability. Recently, balloon pulmonary angioplasty (BPA) has shown promising results as a treatment option for technically inoperable patients, those with unacceptable risk-to-benefit ratio and in a case of residual PH after endarterectomy. Lack of meticulous CTEPH screening programs in post-pulmonary embolism patients leading to underdiagnosis of this condition, complex operability assessment, and diversity in BPA techniques among different institutions are still the issues that need to be addressed. In this paper, we review the recent achievements in the management of non-operable CTEPH, their outcome and safety, based on available data.

Imaging of pulmonary hypertension in adults: a position paper from the Fleischner Society

Pulmonary hypertension (PH) is defined by a mean pulmonary artery pressure greater than 20 mmHg and classified into five different groups sharing similar pathophysiologic mechanisms, haemodynamic characteristics, and therapeutic management. Radiologists play a key role in the multidisciplinary assessment and management of PH. A working group was formed from within the Fleischner Society based on expertise in the imaging and/or management of patients with PH, as well as experience with methodologies of systematic reviews. The working group identified key questions focusing on the utility of CT, MRI, and nuclear medicine in the evaluation of PH: a) Is noninvasive imaging capable of identifying PH? b) What is the role of imaging in establishing the cause of PH? c) How does imaging determine the severity and complications of PH? d) How should imaging be used to assess chronic thromboembolic PH before treatment? e) Should imaging be performed after treatment of PH? This systematic review and position paper highlights the key role of imaging in the recognition, work-up, treatment planning, and follow-up of PH.

Imaging of Pulmonary Hypertension in Adults: A Position Paper from the Fleischner Society

Pulmonary hypertension (PH) is defined by a mean pulmonary artery pressure greater than 20 mm Hg and classified into five different groups sharing similar pathophysiologic mechanisms, hemodynamic characteristics, and therapeutic management. Radiologists play a key role in the multidisciplinary assessment and management of PH. A working group was formed from within the Fleischner Society based on expertise in the imaging and/or management of patients with PH, as well as experience with methodologies of systematic reviews. The working group identified key questions focusing on the utility of CT, MRI, and nuclear medicine in the evaluation of PH: (a) Is noninvasive imaging capable of identifying PH? (b) What is the role of imaging in establishing the cause of PH? (c) How does imaging determine the severity and complications of PH? (d) How should imaging be used to assess chronic thromboembolic PH before treatment? (e) Should imaging be performed after treatment of PH? This systematic review and position paper highlights the key role of imaging in the recognition, work-up, treatment planning, and follow-up of PH. This article is a simultaneous joint publication in Radiology and European Respiratory Journal. The articles are identical except for stylistic changes in keeping with each journal's style. Either version may be used in citing this article. © 2021 RSNA and the European Respiratory Society. Online supplemental material is available for this article.

Chronic Thromboembolic Pulmonary Hypertension: the Bedside

PURPOSE OF REVIEW

Chronic thromboembolic pulmonary hypertension (CTEPH), included in group 4 PH, is an uncommon complication of acute pulmonary embolism (PE), in which emboli in the pulmonary vasculature do not resolve but rather form into an organized scar-like obstruction which can result in right ventricular (RV) failure. Here we provide an overview of current diagnosis and management of CTEPH.

RECENT FINDINGS

CTEPH management is complex with treatments that range from surgery, percutaneous interventions, to medical therapies. Current CTEPH medical therapies have largely been repurposed from pulmonary arterial hypertension (PAH). The diagnosis of CTEPH can be challenging, requiring a multimodality approach to differentiate from disease mimics. While these treatments improve symptoms, they may not reverse the underlying pathology of CTEPH.

Balloon Pulmonary Angioplasty in Patients with Chronic Thromboembolic Pulmonary Hypertension: Impact on Clinical and Hemodynamic Parameters, Quality of Life and Risk Profile

Balloon pulmonary angioplasty (BPA) is a novel treatment option for patients with chronic thromboembolic pulmonary hypertension (CTEPH) who are not eligible for pulmonary endarterectomy (PEA) or suffer from persistent pulmonary hypertension after PEA. The aim of this study was to evaluate the real-life efficacy and safety of BPA in a consecutive group of patients who were diagnosed and treated in the national referral center for CTEPH in the Czech Republic. Here we report data from 160 BPA procedures performed in 64 patients. Efficacy analysis was performed in the subgroup of 25 patients who completed BPA series. Significant improvements were observed in New York Heart Association functional class (4% to 79% in I/II, p < 0.001), 6 min walking test distance (+54.3 m, p < 0.001), risk profile (15.8% to 68.5% with presence of 2/3 low risk criteria, p < 0.001), pulmonary artery mean pressure (−18%, p < 0.001), pulmonary vascular resistance (−32%, p < 0.001), stroke volume (+17%, p = 0.011) and quality of life (+37% in assessment of overall health status by a patient, p < 0.001). We observed 1 fatal periprocedural complication (1.6% of all 64 patients) and 19 BPA-related non-fatal complications (11.9% of all 160 interventions) that predominantly included hemoptysis (10.0% of all sessions). Overall survival at 12 months was 94.6%.

The role of balloon pulmonary angioplasty and pulmonary endarterectomy: Is chronic thromboembolic pulmonary hypertension still a life-threatening disease?

BACKGROUND

The management of non-operable chronic thromboembolic pulmonary hypertension (CTEPH) has evolved with the availability of balloon pulmonary angioplasty (BPA) and pulmonary vasodilators. We launched the BPA program in 2011. The aim was to analyze the survival and treatment efficacy of our CTEPH treatment program in the modern management era.

METHODS AND RESULTS

We retrospectively reviewed data from 143 consecutive CTEPH patients diagnosed from January 2011 (i.e. after the availability of BPA) to December 2019. Of forty-one patients who underwent pulmonary endarterectomy (PEA), 25 underwent additional BPA (Combination group) and the others were treated with only PEA (PEA group). Ninety patients underwent BPA (BPA group). The remaining 12 patients did not undergo any interventional treatments. The 1- and 5-year survival rates of operated patients (n = 41) were 97.4% and 90.0%, compared to 96.9% and 86.9% in not-operated patients (n = 102), respectively (p = 0.579). There was no mortality in the Combination group. Mean pulmonary artery pressure after treatments in the PEA only, Combination, and BPA only groups was 20.5 ± 6.7, 17.9 ± 4.9, and 20.7 ± 4.6 mmHg, respectively (p = 0.067, one-way ANOVA). Percent decrease of pulmonary vascular resistance in each treatment groups was -73.7 ± 11.3%, -74.3 ± 11.8%, and - 54.9 ± 22.5%, respectively (p < 0.01, one-way ANOVA).

CONCLUSION

There was no significant difference in long-term survival between operated and not-operated CTEPH. Moreover, the Combination approach might have the potential to introduce notable improvements in the prognosis of CTEPH. BPA and PEA appear to be mutually complementary therapies in the modern management era.

How should a physician approach the pharmacological management of chronic thromboembolic pulmonary hypertension?

INTRODUCTION

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by the presence of organized thromboembolic material and proliferative fibrous intima occluding varying degrees of the pulmonary arteries, and is also accompanied by small vessel vasculopathy in occluded and non-occluded pulmonary vasculature. The similarity in hemodynamics and pathophysiology between CTEPH and group 1 pulmonary arterial hypertension provides the rationale for clinical use of pulmonary arterial hypertension (PAH)-specific therapy.

AREAS COVERED

The authors present the current knowledge concerning the updated therapeutic strategies in CTEPH, and try to illustrate the established and uncertain role of PAH-specific therapy and anticoagulation therapy. The real-world observational registries and landmark randomized controlled trials of PAH-specific drugs in CTEPH are emphasized in the manuscript.

EXPERT OPINION

Despite surgical and interventional therapies, which could provide effective and potential curable treatments, medical therapies are still the substantial and irreplaceable option for patients with CTEPH. More and more PAH-specific drugs have demonstrated favorable efficacy and safety profiles in patients with CTEPH. Additionally, anticoagulation therapy is also a substantial medical treatment in all CTEPH patients without contradiction. However, the benefit-to-risk balance in life-long anticoagulation and whether more individualized anticoagulation strategies are needed warrants further investigation.

Chronic thromboembolic pulmonary hypertension in Spain: a decade of change

INTRODUCTION AND OBJECTIVES

Chronic thromboembolic pulmonary hypertension (CTEPH) treatment has evolved in the last decade. However, there is scarce information on the long-term impact of this progress in a real-life population at a national level. This study was designed to analyze the characteristics of CTEPH patients in Spain over the last decade.

METHODS

We prospectively collected epidemiological, clinical, and prognostic data from CTEPH patients consecutively included in the Spanish REHAP registry from January 1, 2007, to December 31, 2018. We evaluated differences over time, establishing 2013 as the reference date for analysis. Propensity scores for interventional treatment were calculated using a multivariable logistic regression model.

RESULTS

A total of 1019 patients were included; 659 (64.4%) were evaluated at a national CTEPH center. Overall, 350 patients (34.3%) were selected for surgery and 97 (9.6%) for percutaneous treatment. Patients diagnosed between 2007 and 2012 died more frequently than those diagnosed from 2013 onward (HR, 1.83; 95%CI, 1.07-3.15; P=.027). Within the subgroup of patients adjusted by propensity score, baseline pulmonary vascular resistance and the 6-minute walk test distance also determined the outcome (HR, 1.24; 95%CI, 1.15-1.33; P=.011; and HR, 0.93; 95%CI, 0.90-0.97; P=.001, respectively). High survival rates were found in patients who underwent an invasive procedure (pulmonary endarterectomy or balloon pulmonary angioplasty).

CONCLUSIONS

CTEPH diagnosis and prognosis have consistently improved in the last decade. Baseline disease severity determines the risk profile. Patients who undergo pulmonary endarterectomy or balloon pulmonary angioplasty have better outcomes.

Evolving spectrum of treatment for CTEPH

PURPOSE OF REVIEW

The present review provides an update on treatment of chronic thromboembolic pulmonary hypertension (CTEPH), a rare form of pulmonary hypertension characterized by precapillary pulmonary hemodynamic parameters with chronic thrombotic occlusion of the pulmonary vasculature.

RECENT FINDINGS

Pulmonary thromboendarectomy (PTE) remains the recommended treatment for patients with surgically accessible disease. Recent data suggest that patients preoperatively bridged with medical therapy may have improved outcomes but further research is needed. Riociguat improves hemodynamics, right ventricular function, quality of life, and functional capacity and is the drug of choice for patients with inoperable/persistent disease. Recently published data suggest that endothelin receptor blockers and treprostinil may also have a role in medical management of this patient population. A growing body of evidence indicates that in experienced centers balloon pulmonary angioplasty (BPA) may be a well tolerated and effective adjunct to pharmacological treatment for patients with inoperable disease affecting subsegmental vasculature.

SUMMARY

Untreated CTEPH carries significant morbidity and mortality. Recent publications provide a wealth of data on safety and efficacy of BPA for inoperable subsegmental disease, but its precise fit in the treatment algorithm, both pharmacological and procedural, requires further investigation. PTE remains the procedure of choice for surgically accessible disease.

Balloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension: State of the art

Chronic thromboembolic pulmonary hypertension (CTEPH) is a complex chronic disease in which pulmonary artery stenosis or obstruction caused by organized thrombus can lead to increased pulmonary artery pressure and pulmonary vascular resistance, ultimately triggering progressive right heart failure and death. Currently, its exact mechanism is not fully understood. Pulmonary endarterectomy (PEA) has immediate effects with low perioperative mortality and satisfactory prognosis in experienced expert centers for CTEPH patients with proximal lesions. Nevertheless, 37% of patients are deemed unsuitable for PEA surgery due to comorbidities and other factors, and nearly half of the operated patients have residual or recurrent pulmonary hypertension. Riociguat is the only approved drug for CTEPH, although its effect is limited. Balloon pulmonary angioplasty (BPA) is a promising alternative treatment for patients with CTEPH. After more than 30 years of development and refinements, emerging evidence has confirmed its role in patients with inoperable CTEPH or residual/recurrent pulmonary hypertension, with acceptable complications and comparable long-term prognosis to PEA. This review summarizes the pathophysiology of CTEPH, BPA history and development, therapeutic principles, indications and contraindications, interventional procedures, imaging modalities, efficacy and prognosis, complications and management, bridging and hybrid therapies, ongoing clinical trials and future prospects.

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.

Speckle tracking for predicting outcomes of balloon pulmonary angioplasty in patients with chronic thromboembolic pulmonary hypertension

BACKGROUND

Right ventricular (RV) function is a prognostic marker of chronic thromboembolic pulmonary hypertension (CTEPH). We used two-dimensional (2D) speckle-tracking echocardiography (STE) to evaluate the therapeutic effects of balloon pulmonary angioplasty (BPA) in CTEPH patients.

METHODS

A total of 46 CTEPH patients who underwent 2D STE before and after BPA were enrolled in this retrospective study. The following RV functional parameters were measured: tricuspid annular plane systolic excursion (TAPSE), right ventricular fractional area change (RVFAC), RV index of myocardial performance (RIMP), and free wall longitudinal strain (RVFWLS). Satisfactory BPA was defined as mean pulmonary arterial pressure (mPAP) <25 mm Hg or improvement in mPAP > 10 mm Hg after BPA. Patients were divided into two groups according to mPAP values: group I had satisfactory BPA outcomes; group Ⅱ had unsatisfactory BPA outcomes. The area under the curve (AUC) of the receiver operating characteristic (ROC) curve was used to determine the optimal cutoff values and the ability of RVFWLS to predict successful BPA outcomes.

RESULTS

After BPA, SPAP measured by echocardiography (SPAP_echo ) and RIMP decreased, but TAPSE, RVFAC, and RVFWLS increased. Before BPA, group Ⅰ had significantly better RV function than group Ⅱ. Multifactor logistic regression analysis identified RVFWLS as an independent factor associated with satisfactory BPA outcomes. The optimal cutoff value for RVFWLS in predicting satisfactory BPA outcomes was -12.2%.

CONCLUSIONS

Balloon pulmonary angioplasty improves RV function in CTEPH patients. RVFWLS is a valuable noninvasive tool with which to assess the treatment effects of BPA. CTEPH patients with lower RVFWLS may have limited benefit from BPA.

Chronic thromboembolic pulmonary hypertension - still evolving

Chronic thromboembolic pulmonary hypertension (CTEPH) is one of the leading causes of severe pulmonary hypertension (PH). The disease is still underdiagnosed, and the true prevalence is unknown. CTEPH is characterized by intraluminal non-resolving thrombus organization and fibrous stenosis, or complete obliteration of pulmonary arteries, promoted by progressive remodeling of the pulmonary vasculature. One consequence of this is an increase in pulmonary vascular resistance and pressure, resulting in PH and progressive right heart failure, leading to death if left untreated.

Endovascular disobliteration by pulmonary endarterectomy (PEA) is the preferred treatment for CTEPH patients. PEA surgery is the only technique that can potentially cure CTEPH disease, especially in patients with fresh or organized thrombi of the proximal branches of pulmonary arteries. However, not all patients are eligible for PEA surgery. Recent research has provided evidence suggesting balloon pulmonary angioplasty (BPA) and targeted medical therapy as additional promising available treatments options for inoperable CTEPH and recurrent/persistent PH after PEA surgery.

Studies on BPA have shown it to improve pulmonary hemodynamics, symptoms, exercise capacity and RV function in inoperable CTEPH. Subsequently, BPA has developed into an essential component of the modern era of CTEPH treatment. Large randomized controlled trials have demonstrated varying significant improvements with targeted medical therapy in technically inoperable CTEPH patients. Thus, treatment of CTEPH requires a comprehensive multidisciplinary assessment, including an experienced PEA surgeon, PH specialist, BPA interventionist and CTEPH-trained radiologist at expert centers. In this comprehensive review, we address the latest developments in the fast-evolving field of CTEPH. These include advancements in imaging modalities and developments in operative and interventional techniques, which have widened the range of patients who may benefit from these procedures. The efficacy and safety of targeted medical therapies in CTEPH patients are also discussed. As the treatment options for CTEPH improve, hybrid management involving multiple treatments in the same patient may become a viable option in the near future.

Surgical and Percutaneous Interventions for Chronic Thromboembolic Pulmonary Hypertension

The treatment of chronic thromboembolic pulmonary hypertension has expanded considerably. The ability to endarterectomize chronic thromboembolic material, the availability of pulmonary hypertension medical therapy to treat inoperable chronic thromboembolic pulmonary hypertension and/or residual pulmonary hypertension, and the rebirth of pulmonary balloon angioplasty have changed the management landscape. Patient selection requires a multidisciplinary evaluation at an experienced center. What is inoperable chronic thromboembolic pulmonary hypertension to one group may be operable chronic thromboembolic pulmonary hypertension to another. The ultimate challenge then becomes which intervention provides the optimal long-term outcome for any individual patient.

[Management of right ventricular failure in pulmonary vascular diseases]

Right ventricular failure (RVF) is a common cause of admission to the intensive care unit and its presence is a major prognostic factor in acute pulmonary embolism (PE) and chronic pulmonary hypertension (PH). RVF results from an incapacity of the RV to adapt to an increase in afterload so it can become critical in acute PE and chronic PH. The presence of RVF in cases of acute PE with haemodynamic instability is an indication for thrombolytic therapy. RVF represents the most common cause of death in chronic PH. Factors triggering RV failure in PH, such as infection, PE, arrhythmias, or unplanned withdrawal of pulmonary arterial hypertension (PAH)-targeted therapy, have to be considered and treated if identified. However, RVF may also represent progression to end-stage disease. The management of RVF in patients with PH requires expertise and consists of optimization of fluid balance (with diuretics), cardiac output (with inotropic support such as dobutamine), perfusion pressure (with norepinephrine), and reduction of RV afterload with PAH-targeted therapies. Extracorporeal life support, lung transplantation or heart-lung transplantation should be considered in cases of refractory RVF in eligible patients.

Safety and efficacy of balloon pulmonary angioplasty in chronic thromboembolic pulmonary hypertension in the Netherlands

Background

Balloon pulmonary angioplasty (BPA) is an emerging treatment in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and chronic thromboembolic disease (CTED). We describe the first safety and efficacy results of BPA in the Netherlands.

Methods

We selected all consecutive patients with inoperable CTEPH and CTED accepted for BPA treatment who had a six-month follow-up in the St. Antonius Hospital in Nieuwegein and the Amsterdam University Medical Center (UMC) in Amsterdam. Functional class (FC), N‑terminal pro-brain natriuretic peptide (NT-proBNP), 6‑minute walking test distance (6MWD) and right-sided heart catheterisation were performed at baseline and six months after last BPA. Complications for each BPA procedure were noted.

Results

A hundred and seventy-two BPA procedures were performed in 38 patients (61% female, mean age 65 ± 15 years). Significant improvements six months after BPA treatment were observed for functional class (63% FC I/II to 90% FC I/II, p = 0.014), mean pulmonary artery pressure (−8.9 mm Hg, p = 0.0001), pulmonary vascular resistance (−2.8 Woods Units (WU), p = 0.0001), right atrial pressure (−2.0 mm Hg, p = 0.006), stroke volume index (+5.7 ml/m², p = 0.009) and 6MWD (+48m, p = 0.007). Non-severe complications occurred in 20 (12%) procedures.

Conclusions

BPA performed in a CTEPH expert centre is an effective and safe treatment in patients with inoperable CTEPH.

Treprostinil for the treatment of chronic thromboembolic pulmonary hypertension

Introduction: Parenteral treprostinil for patients with pulmonary arterial hypertension has resulted in improvement of exercise capacity, functional class, hemodynamics, and survival. Recently, a first randomized trial performed in patients with chronic thromboembolic pulmonary hypertension confirmed the efficacy of subcutaneous treprostinil in this subset of pulmonary hypertension. Areas covered: Treprostinil sodium is a prostacyclin analog produced synthetically. Drug characteristics include potent systemic and pulmonary vasodilatory effects. Local side-effects of subcutaneous treprostinil have been an obstacle for its use. However, in contrast to other prostacyclins, treprostinil has favorable features. We performed a literature survey by searching PubMed for clinical trials published in any language, investigating medicinal treatments for CTEPH. We used the search terms 'inoperable', and 'chronic thromboembolic pulmonary hypertension' with 'randomized clinical trial', and have put treprostinil for CTEPH in the contest of published literature. Expert opinion: Drugs approved for PAH have recently shown excellent efficacy in patients with non-operable CTEPH. Rather than head-to-head comparisons of drugs, combination treatments are to be expected in the near future. Furthermore, drugs will have to be tested alongside with pulmonary endarterectomy (PEA), and alongside balloon pulmonary angioplasty, a promising percutaneous mechanical treatment for CTEPH that is not suited for PEA.