Microvascular Disease in Chronic Thromboembolic Pulmonary Hypertension: Hemodynamic Phenotyping and Histomorphometric Assessment.

BACKGROUND: Pulmonary endarterectomy (PEA) is the gold standard treatment for patients with operable chronic thromboembolic pulmonary hypertension. However, persistent pulmonary hypertension (PH) after PEA remains a major determinant of poor prognosis. A concomitant small-vessel arteriopathy in addition to major pulmonary artery obstruction has been suggested to play an important role in the development of persistent PH and survival after PEA. One of the greatest unmet needs in the current preoperative evaluation is to assess the presence and severity of small-vessel arteriopathy. Using the pulmonary artery occlusion technique, we sought to assess the presence and degree of small-vessel disease in patients with chronic thromboembolic pulmonary hypertension undergoing PEA to predict postoperative outcome before surgery. METHODS: Based on pulmonary artery occlusion waveforms yielding an estimate of the effective capillary pressure, we partitioned pulmonary vascular resistance in larger arterial (upstream resistance [Rup]) and small arterial plus venous components (downstream resistance) in 90 patients before PEA. For validation, lung wedge biopsies were taken from nonobstructed and obstructed lung territories during PEA in 49 cases. Biopsy sites were chosen according to the pulmonary angiogram still frames that were mounted in the operating room. All vessels per specimen were measured in each patient. Percent media (%MT; arteries) and intima thickness (%IT; arteries, veins, and indeterminate vessels) were calculated relative to external vessel diameter. RESULTS: Decreased Rup was an independent predictor of persistent PH (odds ratio per 10%, 0.40 [95% CI, 0.23-0.69]; P=0.001) and survival (hazard ratio per 10%, 0.03 [95% CI, 0.00-0.33]; p=0.004). Arterial %MT and %IT of nonobstructed lung territories and venous %IT of obstructed lung territories were significantly increased in patients with persistent PH and nonsurvivors. Rup correlated inversely with %MT (r=-0.72, P<0.001) and %IT (r=-0.62, P<0.001) of arteries from nonobstructed lung territories and with %IT (r=-0.44, P=0.024) of veins from obstructed lung territories. Receiver operating characteristic analysis disclosed that Rup <66% predicted persistent PH after PEA, whereas Rup <60% identified patients with poor prognosis after PEA. CONCLUSIONS: Pulmonary artery occlusion waveform analysis with estimation of Rup seems to be a valuable technique for assessing the degree of small-vessel disease and postoperative outcome after PEA in chronic thromboembolic pulmonary hypertension.

Surgical specimens, haemodynamics and long-term outcomes after pulmonary endarterectomy.

BACKGROUND: Chronic thromboembolic pulmonary hypertension is surgically curable by pulmonary endarterectomy (PEA). It is unclear whether PEA impacts primarily steady state right ventricular afterload (ie, pulmonary vascular resistance (PVR)) or pulsatile right ventricular afterload (ie, pulmonary arterial compliance (C(PA))). Our objectives were to (1) quantify PEA specimens and measure the impact of PEA on PVR and C(PA) in a structure/function study and (2) analyse the effects of haemodynamic changes on long-term survival/freedom of lung transplantation in an outcome study. METHODS: Thrombi were laid out, weighed, photographed and measured. PVR, C(PA) and resistance times compliance (RC-time) were assessed at baseline, within 4 days after PEA ('immediately postoperative') and 1 year after PEA, in 110 consecutive patients who were followed for 34.5 (11.9; 78.3) months. RESULTS: Lengths and numbers of PEA specimen tails were inversely correlated with immediate postoperative PVR (p<0.0001, r=-0.566; p<0.0001, r=-0.580). PVR and C(PA) normalised immediately postoperatively while RC-time remained unchanged. Immediate postoperative PVR was the only predictor of long-term survival/freedom of lung transplantation (p<0.0001). Patients with immediate postoperative PVR<590 dynes.s.cm(-5) had better long-term outcomes than patients with PVR≥590 dynes.s.cm(-5) (p<0.0001, respectively). CONCLUSIONS: PEA immediately decreased PVR and increased C(PA) under a constant RC-time. However, immediate postoperative PVR was the only predictor of long-term survival/freedom of lung transplantation. Our study confirms the importance of a complete, bilateral surgical endarterectomy. Low PVR measured immediately postoperative predicts excellent long-term outcome.

Asymmetric Dimethylarginine and NT-proBNP Levels Provide Synergistic Information in Pulmonary Arterial Hypertension.

BACKGROUND: Plasma asymmetric dimethylarginine (ADMA) is elevated in pulmonary arterial hypertension (PAH) and is associated with unfavorable outcomes. OBJECTIVES: The aim of this study was to assess changes in ADMA plasma levels for monitoring disease progression and outcomes during PAH-specific therapy. METHODS: ADMA was measured at baseline and after at least 6 months of follow-up using enzyme-linked immunosorbent assay and high-performance liquid chromatography. Changes in ADMA were analyzed in relation to changes in established PAH markers, including hemodynamic status, N-terminal pro-brain natriuretic peptide (NT-proBNP) and risk assessment scores. Impact on survival was assessed using Kaplan-Meier curves and Cox proportional hazards models. RESULTS: Between 2008 and 2019, ADMA samples were collected prospectively from 215 patients with PAH. Change in ADMA plasma level was a predictor of disease progression and survival. ΔADMA (median -0.03 µmol/L; 95% CI: -0.145 to 0.0135) was correlated with change in mean pulmonary arterial pressure (P < 0.005; rS = 0.287) but was not significantly correlated with ΔNT-proBNP (P = 0.056; rS = 0.135). Patients with decreased ADMA plasma levels at follow-up had better 3-year and 5-year survival rates (88% and 80%, respectively, vs 72% and 53% in those without decreases in ADMA) (P < 0.005; pulmonary hypertension-related mortality or lung transplantation). Patients with decreases in both ADMA and NT-proBNP had better survival rates compared with patients in whom only 1 parameter improved (P < 0.005). ΔADMA was a significant predictor of survival in Cox regression analysis and also when corrected for ΔNT-proBNP (HRs: 1.27 and 1.35, respectively; P < 0.005). CONCLUSIONS: ADMA and NT-proBNP provide synergistic prognostic information for patients with PAH. ADMA could be used as an objective and distinct biomarker for monitoring treatment response in PAH.

Efficacy and safety of the Aria pulmonary endovascular device in pulmonary hypertension.

AIMS: A common feature of various forms of pulmonary hypertension (PH) is progressive decline of pulmonary arterial compliance (CPA), which correlates with reduced survival. In this acute study, we evaluated feasibility, safety and haemodynamic performance of the Aria pulmonary endovascular device in patients with PH associated with left heart disease (PH-LHD) and chronic lung disease (PH-CLD). METHODS AND RESULTS: Eight patients with PH-LHD and 10 patients with PH-CLD were included in this study. The device was placed in the main pulmonary artery via the right femoral vein and was connected by a catheter to a gas-filled reservoir outside the body. During systole, gas shifts from the balloon to the reservoir, leading to deflation of the balloon. In diastole, the gas returns from the reservoir to the balloon, leading to balloon inflation and enhancing diastolic blood flow to the distal pulmonary capillary bed. Haemodynamics were assessed at baseline, and again with device off, device on and device off. The primary safety endpoint was the incidence of serious adverse events through 30 days after the procedure. No complications or investigational device-related serious adverse events occurred. Device activation in PH-LHD and PH-CLD patients decreased pulmonary arterial pulse pressure by 5.6 ± 4.2 mmHg (-12%; p = 0.003) and 4.2 ± 2.2 mmHg (-11%; p < 0.001), increased CPA by 0.4 ± 0.2 ml/mmHg (+23%; p = 0.004) and 0.4 ± 0.3 ml/mmHg (+25%; p = 0.001), and increased right ventricular-to-pulmonary vascular (RV-PV) coupling by 0.24 ± 0.18 (+40%; p = 0.012) and 0.11 ± 0.07 (+21%; p = 0.001), respectively. CONCLUSIONS: Temporary implantation of the Aria endovascular device was feasible and safe. Device activation resulted in acute improvement of CPA and RV-PV coupling.

Recognition, diagnosis, and operability assessment of chronic thromboembolic pulmonary hypertension (CTEPH): A global cross-sectional scientific survey (CLARITY).

Early recognition and diagnosis of chronic thromboembolic pulmonary hypertension (CTEPH) is crucial for improving prognosis and reducing the disease burden. Established clinical practice guidelines describe interventions for the diagnosis and evaluation of CTEPH, yet limited insight remains into clinical practice variation and barriers to care. The CTEPH global cross-sectional scientific survey (CLARITY) was developed to gather insights into the current diagnosis, treatment, and management of CTEPH and to identify unmet medical needs. This paper focuses on the recognition and diagnosis of CTEPH and the referral and evaluation of these patients. The survey was offered to hospital-based medical specialists through Scientific Societies and other medical organizations, from September 2021 to May 2022. Response data from 353 physicians showed that self-reported awareness of CTEPH increased over the past 10 years among 96% of respondents. Clinical practices in acute pulmonary embolism (PE) follow-up and CTEPH diagnosis differed among respondents. While 50% of respondents working in a nonexpert center reported to refer patients to an expert pulmonary hypertension/CTEPH center when CTEPH is suspected, 51% of these physicians did not report referral of patients with a confirmed diagnosis for further evaluation. Up to 50% of respondents involved in the evaluation of referred patients have concluded a different operability status than that indicated by the referring center. This study indicates that early diagnosis and timely treatment of CTEPH is challenged by suboptimal acute PE follow-up and patient referral practices. Nonadherence to guideline recommendations may be impacted by various barriers to care, which were shown to vary by geographical region.

Treatment and management of chronic thromboembolic pulmonary hypertension (CTEPH): A global cross-sectional scientific survey (CLARITY).

Advances in the treatment of chronic thromboembolic pulmonary hypertension (CTEPH) over the past decade changed the disease landscape, yet global insight on clinical practices remains limited. The CTEPH global cross-sectional scientific survey (CLARITY) aimed to gather information on the current diagnosis, treatment, and management of CTEPH and to identify unmet medical needs. This paper focuses on the treatment and management of CTEPH patients. The survey was circulated to hospital-based medical specialists through Scientific Societies and other medical organizations from September 2021 to May 2022. The majority of the 212 respondents involved in the treatment of CTEPH were from centers performing up to 50 pulmonary endarterectomy (PEA) and/or balloon pulmonary angioplasty (BPA) procedures per year. Variation was observed in the reported proportion of patients deemed eligible for PEA/BPA, as well as those that underwent the procedures, including multimodal treatment and subsequent follow-up practices. Prescription of pulmonary arterial hypertension-specific therapy was reported for a variable proportion of patients in the preoperative setting and in most nonoperable patients. Reported use of vitamin K antagonists and direct oral anticoagulants was similar (86% vs. 82%) but driven by different factors. This study presents heterogeneity in treatment approaches for CTEPH, which may be attributed to center-specific experience and region-specific barriers to care, highlighting the need for new clinical and cohort studies, comprehensive clinical guidelines, and continued education.

Left Ventricular Filling Pressure in Chronic Thromboembolic Pulmonary Hypertension.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by obstruction of major pulmonary arteries with organized thrombi. Clinical risk factors for pulmonary hypertension due to left heart disease including metabolic syndrome, left-sided valvular heart disease, and ischemic heart disease are common in CTEPH patients. OBJECTIVES: The authors sought to investigate prevalence and prognostic implications of elevated left ventricular filling pressures (LVFP) in CTEPH. METHODS: A total of 593 consecutive CTEPH patients undergoing a first diagnostic right and left heart catheterization were included in this study. Mean pulmonary arterial wedge pressure (mPAWP) and left ventricular end-diastolic pressure (LVEDP) were utilized for assessment of LVFP. Two cutoffs were applied to identify patients with elevated LVFP: 1) for the primary analysis mPAWP and/or LVEDP >15 mm Hg, as recommended by the current pulmonary hypertension guidelines; and 2) for the secondary analysis mPAWP and/or LVEDP >11 mm Hg, representing the upper limit of normal. Clinical and echocardiographic features, and long-term mortality were assessed. RESULTS: LVFP was >15 mm Hg in 63 (10.6%) and >11 mm Hg in 222 patients (37.4%). Univariable logistic regression analysis identified age, systemic hypertension, diabetes, atrial fibrillation, calcific aortic valve stenosis, mitral regurgitation, and left atrial volume as significant predictors of elevated LVFP. Atrial fibrillation, calcific aortic valve stenosis, mitral regurgitation, and left atrial volume remained independent determinants of LVFP in adjusted analysis. At follow-up, higher LVFPs were measured in patients who had meanwhile undergone pulmonary endarterectomy (P = 0.002). LVFP >15 mm Hg (P = 0.021) and >11 mm Hg (P = 0.006) were both associated with worse long-term survival. CONCLUSIONS: Elevated LVFP is common, appears to be due to comorbid left heart disease, and predicts prognosis in CTEPH.

Longitudinal analysis of chest Q-SPECT/CT in patients with severe COVID-19.

INTRODUCTION: Patients with COVID-19 have an increased risk for microvascular lung thrombosis. In order to evaluate the type and prevalence of perfusion defects, we performed a longitudinal analysis of combined perfusion single-photon emission and low-dose computed tomography (Q-SPECT/CT scan) in patients with COVID-19 pneumonia. METHODS: Consecutive patients with severe COVID-19 (B.1.1.7 variant SARS-CoV-2) and respiratory insufficiency underwent chest Q-SPECT/CT during hospitalization, and 3 months after discharge. At follow-up (FU), Q-SPECT/CT were analyzed and compared with pulmonary function tests (PFT), blood analysis (CRP, D-dimers, ferritin), modified Medical Research Council (mMRC) dyspnea scale, and high-resolution CT scans (HRCT). Patients with one or more segmental perfusion defects outside the area of inflammation (PDOI) were treated with anticoagulation until FU. RESULTS: At baseline, PDOI were found in 50 of 105 patients (47.6 %). At FU, Q-SPECT/CT scans had improved significantly (p < 0.001) and PDOI were recorded in 14 of 77 (18.2 %) patients. There was a significant correlation between mMRC score and the number of segmental perfusion defects (r = 0.511, p < 0.001), and a weaker correlation with DLCO (r = -0.333, p = 0.002) and KCO (r = -0.373, p = 0.001) at FU. Neither corticosteroid therapy nor HRCT results showed an influence on Q-SPECT/CT changes (p = 0.94, p = 0.74). CRP, D-Dimers and ferritin improved but did not show any association with the FU Q-SPECT/CT results (p = 0.08). CONCLUSION: Segmental mismatched perfusion defects are common in severe COVID-19 and are correlated with the degree of dyspnea. Longitudinal analyses of Q-SPECT/CT scans in severe COVID-19 may help understand possible mechanisms of long COVID and prolonged dyspnea.

EGR1 Is Implicated in Right Ventricular Cardiac Remodeling Associated with Pulmonary Hypertension.

BACKGROUND: Pulmonary hypertension (PH) is a vasoconstrictive disease characterized by elevated mean pulmonary arterial pressure (mPAP) at rest. Idiopathic pulmonary arterial hypertension (iPAH) and chronic thromboembolic pulmonary hypertension (CTEPH) represent two distinct subtypes of PH. Persisting PH leads to right ventricular (RV) hypertrophy, heart failure, and death. RV performance predicts survival and surgical interventions re-establishing physiological mPAP reverse cardiac remodeling. Nonetheless, a considerable number of PH patients are deemed inoperable. The underlying mechanism(s) governing cardiac regeneration, however, remain largely elusive. METHODS: In a longitudinal approach, we profiled the transcriptional landscapes of hypertrophic RVs and recovered hearts 3 months after surgery of iPAH and CTEPH patients. RESULTS: Genes associated with cellular responses to inflammatory stimuli and metal ions were downregulated, and cardiac muscle tissue development was induced in iPAH after recovery. In CTEPH patients, genes related to muscle cell development were decreased, and genes governing cardiac conduction were upregulated in RVs following regeneration. Intriguingly, early growth response 1 (EGR1), a profibrotic regulator, was identified as a major transcription factor of hypertrophic RVs in iPAH and CTEPH. A histological assessment confirmed our biocomputational results, and suggested a pivotal role for EGR1 in RV vasculopathy. CONCLUSION: Our findings improved our understanding of the molecular events driving reverse cardiac remodeling following surgery. EGR1 might represent a promising candidate for targeted therapy of PH patients not eligible for surgical treatment.

The Roles of S100A4 and the EGF/EGFR Signaling Axis in Pulmonary Hypertension with Right Ventricular Hypertrophy.

Pulmonary hypertension (PH) is characterized by increased pulmonary arterial pressure caused by the accumulation of mesenchymal-like cells in the pulmonary vasculature. PH can lead to right ventricular hypertrophy (RVH) and, ultimately, heart failure and death. In PH etiology, endothelial-to-mesenchymal transition (EndMT) has emerged as a critical process governing the conversion of endothelial cells into mesenchymal cells, and S100A4, EGF, and EGFR are implicated in EndMT. However, a potential role of S100A4, EGF, and EGFR in PH has to date not been elucidated. We therefore quantified S100A4, EGF, and EGFR in patients suffering from chronic thromboembolic pulmonary hypertension (CTEPH) and idiopathic pulmonary arterial hypertension (iPAH). To determine specificity for unilateral heart disease, the EndMT biomarker signature was further compared between PH patients presenting with RVH and patients suffering from aortic valve stenosis (AVS) with left ventricular hypertrophy. Reduced S100A4 concentrations were found in CTEPH and iPAH patients with RVH. Systemic EGF was increased in CTEPH but not in iPAH, while AVS patients displayed slightly diminished EGF levels. EGFR was downregulated in all patient groups when compared to healthy controls. Longitudinal data analysis revealed no effect of surgical therapies on EndMT markers. Pulmonary thrombo-endarterectomized samples were devoid of S100A4, while S100A4 tissue expression positively correlated with higher grades of Heath-Edwards histopathological lesions of iPAH-derived lung tissue. Histologically, EGFR was not detectable in CTEPH lungs or in iPAH lesions. Together, our data suggest an intricate role for S100A4 and EGF/EGFR in PH with right heart pathology.

Chronic Thromboembolic Disease and Chronic Thromboembolic Pulmonary Hypertension.

Chronic thromboembolic pulmonary hypertension (CTEPH) and chronic thromboembolic pulmonary vascular disease (CTED) are rare manifestations of venous thromboembolism. Presumably, CTEPH and CTED are variants of the same pathophysiological mechanism. CTEPH and CTED can be near-cured by pulmonary endarterectomy, balloon pulmonary angioplasty, and medical treatment with Riociguat or subcutaneous treprostinil, which are the approved drugs.

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

[Figure: see text].

Pulmonary vascular reactivity and prognosis in patients with chronic thromboembolic pulmonary hypertension: a pilot study.

BACKGROUND: Surgical pulmonary endarterectomy is the preferred treatment for chronic thromboembolic pulmonary hypertension. Persistent pulmonary hypertension after pulmonary endarterectomy has been recognized as a major determinant of poor outcome. We tested whether acute vasoreactivity identifies chronic thromboembolic pulmonary hypertension patients prone to develop persistent/recurrent pulmonary hypertension after pulmonary endarterectomy and whether the degree of acute vasoreactivity affects survival or freedom from lung transplantation. METHODS AND RESULTS: Right-sided heart catheterization at baseline and after inhalation of 40 ppm nitric oxide for 20 minutes was performed in 103 patients (56.3+/-15.3 years old, 53 women). Reductions in mean pulmonary arterial pressure (DeltamPAP; -8.8+/-12.6%; P<0.0001) and pulmonary vascular resistance (-16.1+/-18.1%; P<0.0001) and an increase in mixed venous saturation during inhaled nitric oxide (9.1+/-11.6%; P<0.0001) were observed. Sixty-two patients underwent pulmonary endarterectomy after a median of 49 days (25th and 75th percentiles: 24 and 123 days). Operated patients were followed up for a median of 70.9 months (25th and 75th percentiles: 14 and 97 months). Change in mPAP during inhaled NO was identified as a predictor of persistent/recurrent pulmonary hypertension after pulmonary endarterectomy. Patients experiencing a reduction in mPAP >10.4% with nitric oxide inhalation had a better postoperative outcome. A significant correlation was found between DeltamPAP and immediate postoperative pulmonary vascular resistance (r=0.5, P<0.0001). CONCLUSIONS: A total of 80 (77.7%) of 103 patients demonstrated acute pulmonary vascular reactivity of some degree. A decrease in mPAP >10.4% under inhaled nitric oxide is a predictor of long-term survival and freedom from lung transplantation in adult patients with chronic thromboembolic pulmonary hypertension who are undergoing pulmonary endarterectomy.

Subcutaneous treprostinil for the treatment of severe non-operable chronic thromboembolic pulmonary hypertension (CTREPH): a double-blind, phase 3, randomised controlled trial.

BACKGROUND: Treprostinil, a prostacyclin analogue, is effective for the treatment of pulmonary arterial hypertension. However, information is scarce regarding treprostinil for treatment of chronic thromboembolic pulmonary hypertension (CTEPH). The aim of this study was to examine the efficacy and safety of subcutaneous treprostinil in this setting. METHODS: In this 24-week, randomised, double-blind controlled trial, we enrolled patients with CTEPH, classified as non-operable, or with persistent or recurrent pulmonary hypertension after pulmonary endarterectomy, in six European expert centres in Austria, Czech Republic, Germany, and Poland. Patients in WHO functional class III or IV with a 6-min walk distance of 150-400 m were randomly assigned at a 1:1 allocation ratio to continuous high-dose subcutaneous treprostinil (target dose around 30 ng/kg per min at week 12) or low-dose subcutaneous treprostinil (target dose around 3 ng/kg per min at week 12). The primary endpoint was the change from baseline in 6-min walk distance at week 24. All patients who received at least one dose of the study drug were included in the intention-to-treat efficacy and safety analyses based on assessment of adverse events. The trial was registered at ClinicalTrialsRegister.eu EudraCT number 2008-006441-10 and ClinicalTrials.gov, number NCT01416636. FINDINGS: From March 9, 2009, to June 9, 2016, 105 patients were enrolled with 53 (50%) patients randomly assigned to high-dose and 52 (50%) patients to low-dose subcutaneous treprostinil. At week 24, marginal mean 6-min walk distance improved by 44·98 m (95% CI 27·52 to 62·45) in the high-dose group, and by 4·29 m (95% CI -13·34 to 21·92) in the low-dose group (treatment effect 40·69 m, 95% CI 15·86 to 65·53, p=0·0016). 12 serious adverse events were reported in ten (19%) of 52 patients from the low-dose group and 16 serious adverse events were reported in nine (17%) of 53 patients from the high-dose group. The most common treatment-related adverse events in both groups were infusion site pain and other infusion site reactions. INTERPRETATION: Treatment with subcutaneous treprostinil was safe, and improved exercise capacity in patients with severe CTEPH. Subcutaneous treprostinil provides a parenteral treatment option for patients of WHO functional class III or IV and those who do not tolerate other therapies or need combination treatment. FUNDING: SciPharm Sàrl.

Predictors of outcome in chronic thromboembolic pulmonary hypertension.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by intraluminal thrombus organization and fibrous obliteration of pulmonary arteries. Recently, associated medical conditions such as splenectomy, ventriculoatrial shunt for the treatment of hydrocephalus, permanent central intravenous lines, inflammatory bowel disease, and osteomyelitis were found to be associated with the development of CTEPH. The study aim was to define the impact of these novel risk factors on survival. METHODS AND RESULTS: Between January 1992 and December 2006, 181 patients diagnosed with CTEPH were tracked with the use of our center's customized computer database. A Cox regression model was used to examine relations between survival and associated medical conditions, age, sex, hemodynamic parameters, modified New York Heart Association functional class at diagnosis, CTEPH type, pulmonary endarterectomy, and anti-cardiolipin antibodies/lupus anticoagulant. During a median observation time of 22.1 (range, 0.03 to 152) months, the clinical end point of cardiovascular death or lung transplantation occurred in 48 cases (27%). Pulmonary endarterectomy (hazard ratio, 0.14; 95% CI, 0.05 to 0.41; P=0.0003), associated medical conditions (hazard ratio, 3.17; 95% CI, 1.70 to 5.92; P=0.0003), and pulmonary vascular resistance (hazard ratio, 1.02; 95% CI, 1.00 to 1.04; P=0.04) were predictors of survival. Thirty-day postoperative mortality (24% versus 9%) and the incidence of postoperative pulmonary hypertension (92% versus 20%) were substantially higher in patients with associated medical conditions. CONCLUSIONS: CTEPH-predisposing medical conditions, such as splenectomy, permanent central intravenous lines, and certain inflammatory disorders, predict poor survival in CTEPH.

A clinical comparison of slow- and rapid-escalation treprostinil dosing regimens in patients with pulmonary hypertension.

BACKGROUND AND OBJECTIVE: Subcutaneous treprostinil is an effective treatment for pulmonary arterial hypertension (PAH). A previous pivotal study indicated that infusion site pain was dose dependent and resulted in suboptimal dose escalation by week 12 and a reduced clinical benefit. We hypothesized that a rapid-escalation treprostinil dosing regimen would be as safe and effective as a slow-escalation dosing regimen. METHODS: Twenty-three patients received treprostinil to treat PH of various aetiologies and were randomized into two groups. Group 1 (11 patients: seven females and four males, aged 51.7 +/- 15.4 years) received a slow-escalation regimen, and group 2 (12 patients: ten females and two males, aged 51.3 +/- 16.7 years) were exposed to rapid dose escalation. The dose escalation, exercise capacity (a 6-minute walk test [6WT] or a shuttle walk test [SWT]), WHO classification, blood pressure, heart rate, respiration rate, baseline haemodynamics and adverse events were followed up for 12 weeks. RESULTS: Baseline haemodynamics did not differ significantly between the treatment groups. At follow-up, the treprostinil dose reached 12.9 +/- 2.7 ng/kg/min in group 1 and 20.3 +/- 5.8 ng/kg/min in group 2 (p < 0.01). The patients' WHO classification improved significantly (p < 0.05), with no difference between the groups. Improvement of exercise capacity was greater in group 2 (6WT and SWT, p < 0.05). Infusion site pain occurred in 81.8% of group 1 and in 58.3% of group 2 (p < 0.05) patients. Other adverse events and changes in the heart rate, respiration rate and blood pressure were similar in both groups. CONCLUSION: The rapid-dosing regimen is as safe and effective as the slow-escalation regimen and may be associated with even better clinical outcomes. Infusion site pain is not dose dependent.

The role of treprostinil in the management of pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a severely disabling disorder characterized by sustained elevations of pulmonary vascular resistance, ultimately leading to right-heart failure and death. Intravenous epoprostenol has been widely used in patients with PAH, leading to long-term clinical benefits and improved survival. Epoprostenol has to be delivered through a permanently implanted intravenous catheter, with the potential of life-threatening complications. Thus, treprostinil, a stable prostacyclin analog suitable for subcutaneous administration, has been developed. Treprostinil is chemically stable at room temperature, has a long half-life (2-4 hours), and has similar pharmacologic properties with comparable hemodynamic effects as epoprostenol.A large, double-blind, placebo-controlled, multicenter, 12-week study confirmed the efficacy of subcutaneous treprostinil, by improving exercise capacity, Borg Dypnea Score (BDS), New York Heart Association (NYHA) class, and clinical signs and symptoms in patients with PAH. Subsequently, multiple observational studies reported the long-term effects of subcutaneous treprostinil. The long-term survival of patients treated with subcutaneous treprostinil was similar to that reported with intravenous epoprostenol. Pain at the infusion site has been a major drawback of subcutaneous treprostinil, hampering dose titration and leading to an 8-10% discontinuation rate. In addition, studies have examined the efficacy of intravenous treprostinil in the treatment of patients with PAH. An open-label study demonstrated that intravenous treprostinil improved exercise capacity, BDS, NYHA functional class, and hemodynamics at week 12 compared with baseline. Transitioning from intravenous epoprostenol to intravenous treprostinil is safe and effective. The dose of intravenous treprostinil has to be adjusted to approximately twice the dose of intravenous epoprostenol. Most patients have reported less severe adverse effects with intravenous treprostinil compared with intravenous epoprostenol. The assessment of the long-term efficacy and safety of continuous intravenous treprostinil requires further studies.

Asymmetric dimethylarginine is increased in chronic thromboembolic pulmonary hypertension.

RATIONALE: Asymmetric dimethylarginine (ADMA), a potent endogenous nitric oxide synthase (NOS) inhibitor, is increased in idiopathic pulmonary arterial hypertension and associated with unfavorable outcome. OBJECTIVES: Chronic thromboembolic pulmonary hypertension (CTEPH), although principally amenable to surgical removal of major pulmonary arterial obstructions by pulmonary endarterectomy, may show a small-vessel pulmonary arteriopathy similar to idiopathic pulmonary arterial hypertension. We hypothesized that ADMA plasma levels are increased in patients with CTEPH. METHODS: We measured ADMA by high-performance liquid chromatography at the time of diagnosis in 135 patients with CTEPH. Inoperability in 66 patients was based on an imbalance between severity of pulmonary hypertension and morphologic lesions. MEASUREMENTS AND MAIN RESULTS: ADMA plasma levels were significantly elevated in patients, compared with 40 matched control subjects (0.62 [0.51-0.73] vs. 0.51 [0.45-0.6] micromol/L, P = 0.0002). At baseline, ADMA plasma concentrations correlated with mixed venous saturation (r = -0.25, P = 0.005), right atrial pressure (r = 0.35, P < 0.0001), and cardiac index (r = -0.21, P = 0.01). Patients who underwent surgery demonstrated lower ADMA levels at baseline than inoperable patients (0.60 [0.5-0.68] vs. 0.63 [0.53-0.85] micromol/L, P = 0.02), with a further decrease 12 +/- 1 months after pulmonary endarterectomy (P = 0.02). Endothelial NOS expression in endothelial cells was low in patients with elevated ADMA plasma levels. Survival of patients with ADMA plasma levels >/= 0.64 micromol/L was worse than in patients with ADMA plasma levels < 0.64 micromol/L. CONCLUSIONS: ADMA plasma levels correlate with the severity of pulmonary vascular disease and predict outcome in patients with CTEPH. Measurement of ADMA plasma levels may be useful for estimating the degree of small-vessel arteriopathy in CTEPH.

Treprostinil for pulmonary hypertension.

Treprostinil is a stable, long-acting prostacyclin analogue which can be administered as a continuous subcutaneous infusion using a portable miniature delivery system. Subcutaneous treprostinil has been shown in a large multicenter randomized controlled trial to improve exercise capacity, clinical state, functional class, pulmonary hemodynamics, and quality of life in patients with pulmonary arterial hypertension, an uncommon disease of poor prognosis. Side effects include facial flush, headache, jaw pain, abdominal cramping, and diarrhea, all typical of prostacyclin, and manageable by symptom-directed dose adjustments, and infusion site pain which may make further treatment impossible in 7%-10% of the patients. Long-term survival in pulmonary arterial hypertension patients treated with subcutaneous treprostinil is similar to that reported with intravenous epoprostenol. There are uncontrolled data suggesting efficacy of subcutaneous treprostinil in chronic thromboembolic pulmonary hypertension. Treprostinil can also be administered intravenously, although increased doses, up to 2-3 times those given subcutaneously, appear to be needed to obtain the same efficacy. Preliminary results of a randomized controlled trial of inhaled treprostinil on top of bosentan and sildenafil therapies have shown significance on the primary endpoint, which was exercise capacity as assessed by the distance walked in 6 minutes. Trials of oral formulations of treprostinil have been initiated.