Chronic thromboembolic pulmonary disease.

Chronic thromboembolic pulmonary hypertension is a complication of pulmonary embolism and a treatable cause of pulmonary hypertension. The pathology is a unique combination of mechanical obstruction due to failure of clot resolution, and a variable degree of microvascular disease, that both contribute to pulmonary vascular resistance. Accordingly, multiple treatments have been developed to target the disease components. However, accurate diagnosis is often delayed. Evaluation includes high-quality imaging modalities, necessary for disease confirmation and for appropriate treatment planning. All patients with chronic thromboembolic pulmonary disease, and especially those with pulmonary hypertension, should be referred to expert centres for multidisciplinary team decision on treatment. The first decision remains assessment of operability, and the best improvement in symptoms and survival is achieved by the mechanical therapies, pulmonary endarterectomy and balloon pulmonary angioplasty. With the advances in multimodal therapies, excellent outcomes can be achieved with 3-year survival of >90%.

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 71·5% of baseline in the macitentan group and to 87·6% in the placebo group (geometric means ratio 0·81, 95% CI 0·70-0·95, p=0·0098). 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.

Pulmonary endarterectomy in chronic thromboembolic pulmonary hypertension: Relationship between treated branches and outcome.

BACKGROUND: In patients with chronic thromboembolic pulmonary hypertension (CTEPH) undergoing pulmonary endarterectomy (PEA) it is important to minimize residual obstructions, in order to achieve low postoperative pulmonary vascular resistances and better clinical results. The aim of the study was to test the hypothesis that the greater the number of pulmonary artery branches treated at surgery, the better the hemodynamic and clinical outcome after PEA. METHODS: In 564 consecutive CTEPH patients undergoing PEA the count of the number of treated branches was performed directly on the surgical specimens. Post-operative follow-up visits were scheduled at 3 months and 12 months after surgery including right heart catheterization and modified Bruce test. RESULTS: The population was divided into tertiles based on the number of treated branches: Group 1 (from 4 to 30 treated branches, n = 194 patients); Group 2 (from 31 to 43 treated branches, n = 190 patients); Group 3 (from 44 to 100 treated branches, n = 180 patients). At 3 and at 12 months after PEA, after adjustment for confounders, patients in the highest tertile of treated branches had significantly lower values of pulmonary vascular resistance and higher values of pulmonary arterial compliance as compared to the other two groups (p < 0.002). Hospital mortality was 3% in Group 3, 6% in Group 2 and 10% in Group 1 (overall p = 0.035). CONCLUSIONS: In CTEPH patients undergoing PEA, a higher number of treated pulmonary artery branches is associated with a better hemodynamic and a better clinical outcome at 3 months and 12 months after surgery.

A patient-specific image-based approach to estimate pulmonary artery stiffness based on vessel constitutive model.

An accurate non-invasive evaluation of the mechanical properties of the vessel wall is important for a variety of screening protocols and surgical treatments. In this work, we focused on a section of the Pulmonary Artery (PA), and developed a patient-specific approach to estimate its stiffness in terms of the Young's modulus along the circumferential direction (E). First, we developed a patient-specific semi-automatic approach to estimate its expected value and standard deviation. To this end, pressure-length curves were derived from magnetic resonance images acquired during the cardiac cycle and information on vessel pressure obtained by catheterization. Then, the estimates of E were derived through a maximum likelihood estimation approach based on a vessel constitutive law. In particular, we analyzed the entire PA boundary and an arc free from surrounding organs. Second, we applied the approach to the study of pulmonary endarterectomy (PEA) for the treatment of chronic thromboembolic pulmonary hypertension (CTEPH). We observed a decrease in the circumferential E after PEA for the whole boundary, while no clear trend was observed for the free arc. The low standard deviations associated with the estimates showed high accuracy when considering the entire boundary, while greater variability was observed for the free arc, which was however limited. Finally, reliable hysteretic behavior was obtained from the reconstructed pressure-length curves.

Chronic thromboembolic pulmonary hypertension risk score evaluation and validation (CTEPH SOLUTION): proposal of a study protocol aimed to realize a validated risk score for early diagnosis.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) is the most serious long-term complication of acute pulmonary embolism (PE) though it is the only potentially reversible form of pulmonary hypertension (PH). Its incidence is mainly limited to the first 2 years following the embolic event, however it is often underdiagnosed or misdiagnosed. METHODS: This is a multicenter observational cross-sectional and prospective study. Patients with a prior diagnosis of PE will be enrolled and undergo baseline evaluation for prevalent PH detection through a clinical examination and an echocardiogram as first screening exam. All cases of intermediate-high echocardiographic probability of PH will be confirmed by right heart catheterization and then identified as CTEPH through appropriate imaging and functional examinations in order to exclude other causes of PH. A CTEPH Risk Score will be created using retrospective data from this prevalent cohort of patients and will be then validated on an incident cohort of patients with acute PE. RESULTS: One thousand retrospective and 218 prospective patients are expected to be enrolled and the study is expected to be completed by the end of 2021. Up to now 841 patients (620 retrospective and 221 prospective) have been enrolled. CONCLUSIONS: This study is the first large prospective study for the prediction of CTEPH development in patients with PE. It aims to create a comprehensive scoring tool that includes echocardiographic data which may allow early detection of CTEPH and the application of targeted follow-up screening programs in patients with PE.

Current strategies for managing chronic thromboembolic pulmonary hypertension: results of the worldwide prospective CTEPH Registry.

BACKGROUND: Pulmonary endarterectomy (PEA), pulmonary arterial hypertension (PAH) therapy and balloon pulmonary angioplasty (BPA) are currently accepted therapies for chronic thromboembolic pulmonary hypertension (CTEPH). This international CTEPH Registry identifies clinical characteristics of patients, diagnostic algorithms and treatment decisions in a global context. METHODS: 1010 newly diagnosed consecutive patients were included in the registry between February 2015 and September 2016. Diagnosis was confirmed by right heart catheterisation, ventilation-perfusion lung scan, computerised pulmonary angiography and/or invasive pulmonary angiography after at least 3 months on anticoagulation. RESULTS: Overall, 649 patients (64.3%) were considered for PEA, 193 (19.1%) for BPA, 20 (2.0%) for both PEA and BPA, and 148 (14.7%) for PAH therapy only. Reasons for PEA inoperability were technical inaccessibility (n=235), comorbidities (n=63) and patient refusal (n=44). In Europe and America and other countries (AAO), 72% of patients were deemed suitable for PEA, whereas in Japan, 70% of patients were offered BPA as first choice. Sex was evenly balanced, except in Japan where 75% of patients were female. A history of acute pulmonary embolism was reported for 65.6% of patients. At least one PAH therapy was initiated in 35.8% of patients (26.2% of PEA candidates, 54.5% of BPA candidates and 54.1% of those not eligible for either PEA or BPA). At the time of analysis, 39 patients (3.9%) had died of pulmonary hypertension-related causes (3.5% after PEA and 1.8% after BPA). CONCLUSIONS: The registry revealed noticeable differences in patient characteristics (rates of pulmonary embolism and sex) and therapeutic approaches in Japan compared with Europe and AAO.

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 endarterectomy in the octogenarian population: safety and outcomes.

AIMS: Aim of the study was to verify the feasibility, safety and efficacy of pulmonary endarterectomy (PEA) in octogenarian patients with chronic thromboembolic pulmonary hypertension. METHODS: We retrospectively analyzed 635 chronic thromboembolic pulmonary hypertension patients who underwent PEA at our center and were followed-up for at least 1 year. The end-points of the study were in-hospital mortality, hemodynamic results at 1 year and long-term survival. RESULTS: In-hospital mortality was 4, 10 and 17%, respectively, for 259 patients under the age of 60 years, 352 aged between 60 and 79 years and 24 octogenarians (P = 0.006 octogenarians vs. <60 years). At multivariable analysis, age and pulmonary vascular resistances were independent risk factors for mortality (P = 0.021 and P < 0.001, respectively). At 1 year, the improvement in cardiac index was lower and the distance walked in 6 min was poorer for octogenarians than for the other two groups (both P = 0.001). Survival after hospital discharge was similar over a median follow-up period of 59 months (P = 0.113). Although in-hospital mortality and long-term survival are similar in octogenarians as compared with patients aged between 60 and 79, the improvement in cardiac index and in functional capacity at 1 year are lower in this very elderly population. CONCLUSION: Age over 80 years should not be a contraindication to PEA surgery in selected patients operated on in referral centers.

Acute massive pulmonary embolism during patient repositioning following excision of a thymic carcinoma in a patient affected by cryoglobulinemia.

Acute pulmonary embolism (APE) is a well-described complication following surgical procedures. The incidence of such a complication can be related to the presence of a peculiar patient's condition. Cryoglobulinemia, which consists in the presence of one or more immunoglobulins in the serum that precipitate at temperatures below 37°C and redissolve on warming, seems to increase the risk of thrombotic events. Treatment options of APE, according to clinical severity, include systemic thrombolysis, surgical embolectomy, and systemic anticoagulation. Thrombolysis is considered the first-line treatment, whereas surgery is reserved in case of extremely-compromised hemodynamic conditions related to massive central embolism, and in case of contraindication to thrombolysis. Here, we report a case of acute massive pulmonary embolism occurring at the end of a surgical procedure for a thymic carcinoma resection, in a patient with cryoglobulinemia, which required an emergent surgical pulmonary embolectomy.

Persistent exercise limitation after successful pulmonary endoarterectomy: frequency and determinants.

BACKGROUND: After successful pulmonary endoarterectomy (PEA), patients may still suffer from exercise limitation, despite normal pulmonary vascular resistance. We sought to assess the proportion of these patients after the extension of PEA to frail patients, and the determinants of exercise limitation. METHODS: Out of 553 patients treated with PEA from 2008 to 2016 at our institution, a cohort of 261 patients was followed up at 12 months. They underwent clinical, haemodynamic, echocardiographic, respiratory function tests and treadmill exercise testing. A reduced exercise capacity was defined as Bruce test distance < 400 m. RESULTS: Eighty patients did not had exercise testing because of inability to walk on treadmill and/or ECG abnormalities Exercise limitation 12 months after PEA was present in 74/181 patients (41, 95%CI 34 to 48%). The presence of COPD was more than double in patients with exercise limitation than in the others. Patients with persistent exercise limitation had significantly higher mPAP, PVR, HR and significantly lower RVEF, PCa, CI, VC, TLC, FEV1, FEV1/VC, DLCO, HbSaO2 than patients without. The multivariable model shows that PCa at rest and TAPSE are important predictors of exercise capacity. Age, COPD, respiratory function parameters and unilateral surgery were also retained. CONCLUSIONS: After successful PEA, most of the patients recovered good exercise tolerance. However, about 40% continues to suffer from limitation to a moderate intensity exercise. Besides parameters of right ventricular function, useful information are provided by respiratory function parameters and COPD diagnosis. This could be useful to better address the appropriate therapeutic approach.

Surgical Treatment for Pulmonary Embolization of a Right Atrial Myxoma.

We report the case of a woman with pulmonary embolism due to a cardiac mass. Echocardiography, computed tomography scan, and cardiac magnetic resonance raised the suspicion of right atrial myxoma and confirmed the presence of pulmonary embolism. The patient was sent to the University of Pavia School of Medicine, where the atrial myxoma was excised, and, using interrupted periods of circulatory arrest, extraction of the myxoma emboli from the pulmonary arteries was performed. No adjuvant chemotherapy was required as surgical treatment is an effective therapy in cases of pulmonary embolism of a benign neoplastic mass.

Chronic thromboembolic pulmonary hypertension: Reversal of pulmonary hypertension but not sleep disordered breathing following pulmonary endarterectomy.

BACKGROUND: It has been hypothesized that pre-capillary pulmonary hypertension (PH) may trigger sleep disordered breathing (SDB). In patients with chronic thromboembolic PH (CTEPH), pulmonary endarterectomy (PEA) is potentially effective to improve PH. We assessed the pre- and post-operative prevalence of SDB in CTEPH patients submitted to PEA and the relationship between SDB and clinical, pulmonary and hemodynamic factors. METHODS: Unattended cardiorespiratory recording was performed the night before and one month after elective PEA in 50 patients. RESULTS: Before the intervention SDB prevalence (obstructive or central AHI ≥ 5/h) was 64%: 18 patients (66% female) had No-SDB, 22 (68% female) had dominant obstructive (dOSA), and 10 (20% female) had dominant central sleep apnea (dCSA). There were no differences in risk factors and the need for supplemental oxygen. Mean right atrial (mRAP) and pulmonary artery pressures (mPAP) showed a more compromised profile from No-SDB to dOSA and dCSA (mRAP: 5.5 ±â€¯3.9 vs 7.0 ±â€¯4.5 vs 9.7 ±â€¯4.3 mm Hg (p = 0.054), mPAP: 39 ±â€¯12 vs 48 ±â€¯11 vs 51 ±â€¯16 mm Hg (p = 0.0.47)). By contrast, cardiac index did not differ. At post-intervention, the prevalence of SDB was 68%: 16 patients had No-SDB, while 30 had dOSA and 4 dCSA, with no relationship with the relief from PH. Interestingly, 5 patients with previous CSA moved to the OSA group and 2 normalized. CONCLUSIONS: Prevalence of SDB is high in patients with CTEPH even after resolution of PH. Our data support the hypothesis that pre-capillary PH may trigger CSA but not OSA, and suggest that OSA may play a role in the development of CTEPH.

Neuropsychological outcomes after pulmonary endarterectomy using moderate hypothermia and periodic circulatory arrest.

BACKGROUND: In this prospective, single-center, observational study, we investigated the association between repeated short periods of circulatory arrest with moderate hypothermia during pulmonary endarterectomy (PEA) in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and different neuropsychological dimensions. METHODS: We examined 70 patients with CTEPH, >18 to 80 years of age, who had been treated with PEA. Neuropsychological testing was performed. RESULTS: Learning ability and delayed memory remained well within the normal range for patients' age. We found a statistically significant post-surgical improvement in motor speed, which was accompanied by a better quality of life and reduced symptoms of depression and anxiety. CONCLUSION: PEA with repeated short periods of circulatory arrest in CTEPH did not result in any neuropsychological complications and may even lead to post-surgical psychological improvements.

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.

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.

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.

Predictors of long-term outcomes in patients treated with riociguat for chronic thromboembolic pulmonary hypertension: data from the CHEST-2 open-label, randomised, long-term extension trial.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare, debilitating, and life-threatening disease. We investigated associations between markers of disease severity and long-term outcomes in patients with inoperable CTEPH or persistent or recurrent pulmonary hypertension after pulmonary endarterectomy (PEA) who were receiving the soluble guanylate cyclase stimulator riociguat. We also present safety and efficacy from the final data cutoff of CHEST-2, where most patients had received riociguat for at least 2 years. METHODS: Eligible patients from the CHEST-1 study entered the CHEST-2 open-label extension study, in which all patients received riociguat individually adjusted to a maximum dose of 2·5 mg three times per day. The primary endpoint was safety and tolerability. We did exploratory assessments of associations between markers of disease severity (6-min walking distance [6MWD], N-terminal prohormone of brain natriuretic peptide [NT-proBNP] concentration, and WHO functional class) at baseline and follow-up with overall survival and clinical worsening-free survival. We used Kaplan-Meier and Cox proportional hazards analyses. CHEST-2 is registered at ClinicalTrials.gov, number NCT00910429. FINDINGS: 237 patients entered CHEST-2. At 2 years, overall survival was 93% (95% CI 89-96) and clinical worsening-free survival was 82% (77-87). A significant association with overall survival was seen for 6MWD and NT-proBNP concentration at baseline (p=0·0199 and p=0·0183, respectively) and at follow-up (p=0·0385 and p=0·0068, respectively). Change from baseline in 6MWD was also significantly associated with survival (p=0·0047). WHO functional class at baseline and follow-up showed no significant association with overall survival but was associated with clinical worsening-free survival. Riociguat was well tolerated by most patients and no new safety signals were identified. Serious adverse events were seen in 129 (54%) of 237 patients, and 14 (6%) discontinued riociguat therapy because of adverse events. INTERPRETATION: Riociguat may be used long term in patients with CTEPH. 6MWD and NT-proBNP concentration are good prognostic markers. FUNDING: Bayer Pharma AG.

Operability assessment in CTEPH: Lessons from the CHEST-1 study.

Pulmonary endarterectomy is the gold standard treatment for chronic thromboembolic pulmonary hypertension and is potentially curative, although some patients are unsuitable for pulmonary endarterectomy and require alternative management. Lack of standardized assessment of pulmonary endarterectomy eligibility risks suboptimal treatment in some patients. We discuss the implications for future clinical trials and practice of a unique operability assessment in patients who have chronic thromboembolic pulmonary hypertension and were initially screened for inclusion in the CHEST-1 (Chronic Thromboembolic Pulmonary Hypertension Soluble Guanylate Cyclase Stimulator Trial-1) study. The CHEST-1 study evaluated riociguat for the treatment of inoperable chronic thromboembolic pulmonary hypertension (CTEPH) or persistent/recurrent pulmonary hypertension after pulmonary endarterectomy. Screened patients who were initially considered "inoperable" underwent central independent adjudication by a committee of experienced surgeons, or local adjudication in collaboration with an experienced surgeon. Operability decisions were based on accessibility of thrombi and the association between pulmonary vascular resistance (PVR) and the extent of obstruction, using pulmonary angiography/computed tomography with ventilation/perfusion scintigraphy as the minimum diagnostic tests. Of 446 patients screened for CHEST-1, a total of 188 and 124 underwent central and local adjudication, respectively, after being initially considered to be "inoperable." After a second assessment by an experienced surgeon, 69 of these 312 "inoperable" patients were deemed operable. Rigorous measures in CHEST-1 guaranteed that only technically inoperable patients, or patients who had persistent/recurrent pulmonary hypertension, were enrolled, thus ensuring that only patients for whom surgery was not an option were enrolled. This study design sets new standards for future clinical trials and practice in CTEPH, helping to ensure that patients who have CTEPH receive optimal treatment.