Meta-analysis of randomized controlled trials of bosentan for treatment of pulmonary arterial hypertension

BACKGROUND/AIMS

We assessed the efficacy and safety of bosentan in patients with pulmonary arterial hypertension (PAH).

METHODS

We surveyed randomized controlled trials (RCTs) of the efficacy and safety of bosentan in patients with PAH using MEDLINE, EMBASE, the Cochrane Controlled Trials Register, and manual searches. Meta-analysis of RCTs was performed to determine treatment efficacy and safety outcomes. Results are presented as odds ratios (ORs) or weighted mean differences (WMDs).

RESULTS

Meta-analysis of seven RCTs including a total of 410 patients and 296 controls revealed that the 6-minute work distance was significantly higher in the bosentan group than in the placebo group (WMD, 46.19; 95% confidence interval [CI], 21.20 to 71.19; p = 2.9 × 10(-5)). Compared with the placebo, bosentan significantly reduced the mean pulmonary arterial pressure in patients with PAH (WMD, -6.026; 95% CI, -8.785 to -3.268, p = 1.8 × 10(-6)). The bosentan therapy group worsened less clinically than the placebo group (OR, 0.252; 95% CI, 0.140 to 0.454; p = 4.6 × 10(-7)). The incidence of serious adverse events did not differ between the bosentan and placebo groups (OR, 0.948; 95% CI, 0.556 to 1.614; p = 0.843). However, the results of the abnormal liver function test (LFT) were significantly higher in the bosentan group than in the placebo group (OR, 2.312; 95% CI, 1.020 to 5.241; p = 0.045).

CONCLUSIONS

This meta-analysis shows that bosentan can treat PAH effectively. However, bosentan increased the incidence of abnormal LFT results compared with the placebo.

Endothelial injury in a transforming growth factor β-dependent mouse model of scleroderma induces pulmonary arterial hypertension

OBJECTIVE

To delineate the constitutive pulmonary vascular phenotype of the TβRIIΔk-fib mouse model of scleroderma, and to selectively induce pulmonary endothelial cell injury using vascular endothelial growth factor (VEGF) inhibition to develop a model with features characteristic of pulmonary arterial hypertension (PAH).

METHODS

The TβRIIΔk-fib mouse strain expresses a kinase-deficient transforming growth factor β (TGFβ) receptor type II driven by a fibroblast-specific promoter, leading to ligand-dependent up-regulation of TGFβ signaling, and replicates key fibrotic features of scleroderma. Structural, biochemical, and functional assessments of pulmonary vessels, including in vivo hemodynamic studies, were performed before and following VEGF inhibition, which induced pulmonary endothelial cell apoptosis. These assessments included biochemical analysis of the TGFβ and VEGF signaling axes in tissue sections and explanted smooth muscle cells.

RESULTS

In the TβRIIΔk-fib mouse strain, a constitutive pulmonary vasculopathy with medial thickening, a perivascular proliferating chronic inflammatory cell infiltrate, and mildly elevated pulmonary artery pressure resembled the well-described chronic hypoxia model of pulmonary hypertension. Following administration of SU5416, the pulmonary vascular phenotype was more florid, with pulmonary arteriolar luminal obliteration by apoptosis-resistant proliferating endothelial cells. These changes resulted in right ventricular hypertrophy, confirming hemodynamically significant PAH. Altered expression of TGFβ and VEGF ligand and receptor was consistent with a scleroderma phenotype.

CONCLUSION

In this study, we replicated key features of systemic sclerosis-related PAH in a mouse model. Our results suggest that pulmonary endothelial cell injury in a genetically susceptible mouse strain triggers this complication and support the underlying role of functional interplay between TGFβ and VEGF, which provides insight into the pathogenesis of this disease.

Deletion of the sequence encoding the tail domain of the bone morphogenetic protein type 2 receptor reveals a bone morphogenetic protein 7-specific gain of function

The bone morphogenetic protein (BMP) type II receptor (BMPR2) has a long cytoplasmic tail domain whose function is incompletely elucidated. Mutations in the tail domain of BMPR2 are found in familial cases of pulmonary arterial hypertension. To investigate the role of the tail domain of BMPR2 in BMP signaling, we generated a mouse carrying a Bmpr2 allele encoding a non-sense mediated decay-resistant mutant receptor lacking the tail domain of Bmpr2. We found that homozygous mutant mice died during gastrulation, whereas heterozygous mice grew normally without developing pulmonary arterial hypertension. Using pulmonary artery smooth muscle cells (PaSMC) from heterozygous mice, we determined that the mutant receptor was expressed and retained its ability to transduce BMP signaling. Heterozygous PaSMCs exhibited a BMP7‑specific gain of function, which was transduced via the mutant receptor. Using siRNA knockdown and cells from conditional knockout mice to selectively deplete BMP receptors, we observed that the tail domain of Bmpr2 inhibits Alk2‑mediated BMP7 signaling. These findings suggest that the tail domain of Bmpr2 is essential for normal embryogenesis and inhibits Alk2‑mediated BMP7 signaling in PaSMCs.

Nuclear factor κ-B is activated in the pulmonary vessels of patients with end-stage idiopathic pulmonary arterial hypertension

OBJECTIVES

To assess activation of the inflammatory transcription factor NF-kappa B (NF-κB) in human idiopathic pulmonary arterial hypertension (PAH).

BACKGROUND

Idiopathic PAH is a severe progressive disease characterized by pulmonary vascular remodeling and excessive proliferation of vascular cells. Increasing evidence indicates that inflammation is important in disease pathophysiology.

METHODS

NF-κB-p65 and CD68, CD20 and CD45 were measured by immunohistochemistry and confocal microscopy on lung specimens from patients with idiopathic PAH (n = 12) and controls undergoing lung surgery (n = 14). Clinical data were recorded for all patients including invasive pulmonary hemodynamics for the PAH patients. Immunohistochemical images were analyzed by blinded observers to include standard pulmonary vascular morphometry; absolute macrophage counts/mm(2) and p65-positivity (p65+) using composite images and image-analysis software; and cytoplasmic:nuclear p65+ of individual pulmonary arterial endothelial and smooth muscle cells (PASMC) in 10-20 pulmonary arteries or arterioles per subject. The expression of ET-1 and CCL5 (RANTES) in whole lung was determined by RT-qPCR.

RESULTS

Macrophage numbers were increased in idiopathic PAH versus controls (49.0±4.5 vs. 7.95±1.9 macrophages/100 mm(2), p<0.0001): these macrophages demonstrated more nuclear p65+ than in macrophages from controls (16.9±2.49 vs. 3.5±1.25%, p<0.001). An increase in p65+ was also seen in perivascular lymphocytes in patients with PAH. Furthermore, NF-κB activation was increased in pulmonary arterial endothelial cells (62.3±2.9 vs. 14.4±3.8, p<0.0001) and PASMC (22.6±2.3 vs. 11.2±2.0, p<0.001) in patients with PAH versus controls, with similar findings in arterioles. Gene expression of both ET-1 mRNA ((0.213±0.069 vs. 1.06±0.23, p<0.01) and CCL5 (RANTES) (0.16±0.045 vs. 0.26±0.039, p<0.05) was increased in whole lung homogenates from patients with PAH.

CONCLUSIONS

NF-κB is activated in pulmonary macrophages, lymphocytes, endothelial and PASMC in patients with end-stage idiopathic PAH. Future research should determine whether NF-κB activation is a driver or bystander of pulmonary vascular inflammation and if the former, its potential role as a therapeutic target.

Exhaled nitric oxide measurement to monitor pulmonary hypertension in a pneumonectomy-monocrotaline rat model

The use of fractional exhaled nitric oxide (FeNO) has been suggested as a quantitative marker for pulmonary arterial hypertension (PAH) in humans. To further characterize FeNO in PAH we investigated this marker in a rodent model. Since there is no standardized technique for FeNO measurement in animals, we intended to reduce measuring errors and confounders of an existing published method by mathematical modification and tested its applicability in an NO-regulating therapy concept of PAH. Thirty-three male Sprague-Dawley rats underwent unilateral pneumonectomy and monocrotaline (MCT) injection and were observed for 49 days. A telemetric catheter was introduced into the left pulmonary artery to continuously record mean pulmonary arterial pressure (mPAP), and FeNO was assessed. After 35 days, animals were randomized to receive either oral l-arginine (300 mg/kg) in combination with tetrahydrobiopterin (20 mg/kg) therapy (n = 12) or vehicle (n = 11) daily over a period of 14 days. mPAP at baseline was 17.19 ± 9.62 mmHg, which increased to 53.1 ± 10.63 mmHg 28 days after monocrotaline exposure (P < 0.001). Using the modified technique, we found an inverse correlation between exhaled NO and pulmonary pressures before (r = -0.366, P = 0.043) and after MCT (r = -0.363, P = 0.038) as well as after therapy administration (r = -0.657, P = 0.02). Our modified technique proved robust in a rodent model, since valid and reproducible data were gained and showed an inverse correlation between exhaled NO and mPAP, whereas the existing method did not.

Circulating ghrelin was negatively correlated with pulmonary arterial pressure in atrial septal defect patients

BACKGROUND

Ghrelin was found to attenuate the magnitude of pulmonary arterial hypertension and pulmonary vascular remodeling in rats. The objective of this study was to explore the fasting plasma ghrelin level and the relationships between ghrelin and pulmonary arterial pressure (PAP) in atrial septal defect (ASD) patients with pulmonary arterial hypertension (PAH).

METHODS

Fasting plasma ghrelin, obestatin, and insulin levels were measured by enzyme linked immunosorbent assay (ELISA) method in ASD patients with or without PAH according to the manufacturer's instructions. Insulin resistance was calculated by the homeostasis model of assessment for insulin resistance (HOMA-IR) approach, calculated as fasting insulin (microunits/ml)× fasting blood glucose (mmol/L)/22.5. Comparisons between the parameters of patients with PAH and those of patients with normal PAP were performed with an unpaired Student's t test. The relationships between ghrelin and various clinical parameters were examined by bivariate correlations and multiple regression analysis.

RESULTS

We found that the fasting plasma ghrelin level and the ratio of ghrelin to obestatin were significantly lower in the PAH group compared with the control group ((582.4±12.8) pg/ml vs. (1045.2±95.5) pg/ml, P < 0.05 and 30.5±4.9 vs. 70.0±9.7, P < 0.01). The fasting plasma obestatin level was higher in the PAH group compared with the control group, but the difference between them was not significant ((23.2±3.1) pg/ml vs. (16.3±1.6) pg/ml, P > 0.05). In a multiple regression model analysis, only mean PAP was an independent predictor of ghrelin and the ratio of ghrelin to obestatin (standardized coefficient = -0.737, P < 0.001 and standardized coefficient = -0.588, P = 0.006, respectively).

CONCLUSION

Ghrelin is negatively correlated with mean PAP and this suggests that circulating ghrelin might predict the severity of pulmonary hypertension in ASD patients with PAH.

[Pulmonary vascular remodeling in congenital cardiovascular abnormalities: an eternal topic]

Pulmonary arterial hypertension (PAH) is one of the most severe complications of congenital heart defects with left to right shunt. Pulmonary vascular remodeling (PVR) is extremely essential in PAH. Therefore, prevention and reversion of PVR is one of the most important factors for improving quality of life for children suffering from PAH. In this article we reviewed the emerging research views on PVR from the disciplines of oncology and anti-tumor pharmacy. Two main sections were included. On the one hand, we introduced the "ATM signal turning point hypothesis" from the DNA damage response (DDR) mechanism research in oncology. The hypothesis suggests that the tumor-like proliferation of vascular smooth muscle cells might be the pathological basis of obstructive PAH. On the other hand, a new lung-targeted drug delivery system based on the fact that low concentration of anti-tumor drugs can inhibit angiogenesis without cellular toxicity was introduced. These new research directions could extend current practice in PVR therapy.

Pulmonary blood volume indexed to lung volume is reduced in newly diagnosed systemic sclerosis compared to normals--a prospective clinical cardiovascular magnetic resonance study addressing pulmonary vascular changes

BACKGROUND

Pulmonary involvement, manifested as pulmonary arterial hypertension or pulmonary fibrosis, is the most common cause of death in systemic sclerosis (SSc). We aimed to explore the feasibility of detecting early pulmonary involvement in SSc using recently developed non-invasive quantitative measures of pulmonary physiology using cardiovascular magnetic resonance (CMR).

METHODS

Twenty-seven SSc patients (9 men, 57 ± 13 years) and 10 healthy controls (3 men, 54 ± 9 years) underwent CMR to determine the pulmonary blood volume (PBV) and the PBV variation (PBVV) throughout the cardiac cycle. Patients underwent Doppler echocardiography, high-resolution computed tomography (HRCT), and pulmonary function testing by spirometry. Comparisons were performed using the unpaired t-test and linear regression analysis was performed with Pearson's correlation coefficient (r).

RESULTS

Compared to healthy controls, the PBV indexed to lung volume (PBVI) was lower in patients (16 ± 4 vs 20 ± 5%, p < 0.05). There was no difference in PBV (466 ± 87 vs 471 ± 122 mL, p = 0.91) or PBVV/stroke volume (45 ± 10 vs 40 ± 6%, p = 0.09). There were no significant correlations between PBVI and pulmonary artery pressure estimated by Doppler (p = 0.08) the lung's diffusion capacity for carbon monoxide (DLCO) (p = 0.09), vital capacity (p = 0.45), or pulmonary fibrosis by HRCT (p = 0.74).

CONCLUSIONS

This study is the first to measure the PBV in humans using CMR. Compared to healthy controls, newly diagnosed SSc patients have a reduced amount of blood in the pulmonary vasculature (PBVI) but unchanged pulmonary vascular distensibility (PBVV/stroke volume). PBVI is unrelated to DLCO, pulmonary artery pressure, vital capacity, and the presence of pulmonary fibrosis. PBVI may be a novel parameter reflecting vascular lung involvement in early-stage SSc, and these findings may be consistent with pathophysiological changes of the pulmonary vasculature.

Wall shear stress measured by phase contrast cardiovascular magnetic resonance in children and adolescents with pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is a devastating disease with significant morbidity and mortality. At the macroscopic level, disease progression is observed as a complex interplay between mean pulmonary artery pressure, pulmonary vascular resistance, pulmonary vascular stiffness, arterial size, and flow. Wall shear stress (WSS) is known to mediate or be dependent on a number of these factors. Given that WSS is known to promote architectural vessel remodeling, it is imperative that the changes of this factor be quantified in the presence of PAH.

METHODS

In this study, we analyzed phase contrast imaging of the right pulmonary artery derived from cardiovascular magnetic resonance to quantify the local, temporal and circumferentially averaged WSS of a PAH population and a pediatric control population. In addition, information about flow and relative area change were derived.

RESULTS

Although the normotensive and PAH shear waveform exhibited a WSS profile which is uniform in magnitude and direction along the vessel circumference at systole, time-averaged WSS (2.2 ± 1.6 vs. 6.6 ± 3.4 dynes/cm(2), P = 0.018) and systolic WSS (8.2 ± 5.0 v. 20.0 ± 9.1 dynes/cm(2), P = 0.018) was significantly depressed in the PAH population as compared to the controls. BSA-indexed PA diameter was significantly larger in the PAH population (1.5 ± 0.4 vs. 0.7 ± 0.1 cm/m(2), P = 0.003).

CONCLUSIONS

In the presence of preserved flow rates through a large PAH pulmonary artery, WSS is significantly decreased. This may have implications for proximal pulmonary artery remodeling and cellular function in the progression of PAH.

Prognostic relevance of changes in exercise test variables in pulmonary arterial hypertension

INTRODUCTION

Exercise variables determined in patients with pulmonary arterial hypertension (PAH) at the time of diagnosis, predict survival. It is unknown whether upon treatment, subsequent changes in these exercise variables reflect improvements in survival. The aim of this study was to determine changes in exercise variables in PAH patients and to relate these changes to survival.

METHODS

Baseline cardiopulmonary exercise test (CPET) variables and six-minute-walk-distance (6MWD) were available from 65 idiopathic PAH patients (50 females; mean age 45±2yrs). The same variables were determined after treatment (13months) in a sub group of 43 patients. To estimate the association between changes in exercise variables and changes in cardiac function, right-ventricle ejection fraction (RVEF) was measured by cardiac MRI at baseline and after treatment in 34 patients. Mean follow-up time after the second CPET was 53 (range: 4-111) months. Kaplan-Meier analysis was used to relate survival to baseline and treatment-associated changes in exercise variables.

RESULTS

Survivors showed a significantly greater change in maximal oxygen uptake than non-survivors and this change in aerobic capacity was significantly related to changes in RVEF. From baseline until the end of the study period, two patients underwent a lung transplantation and 19 patients died. Survival analysis showed that baseline 6MWD (p<0.0001), maximal heart rate (p<0.0001) and the slope relating ventilation with carbon dioxide production (p≤0.05) were significant predictors of survival, whereas baseline oxygen uptake and oxygen pulse held no predictive value. Treatment associated changes in 6MWD (p<0.01), maximal heart rate (p<0.05), oxygen uptake (p<0.001) and oxygen pulse predicted survival (p<0.05), whereas changes in the slope relating ventilation with carbon dioxide production did not.

CONCLUSION

Exercise variables with prognostic significance when determined at baseline, retain their prognostic relevance after treatment. However, when changes in exercise variables upon treatment are considered, a different set of variables provides prognostic information.

[Pregnancy outcomes of 103 women with pulmonary arterial hypertension]

OBJECTIVE

To evaluate the pregnancy outcome of women with pulmonary arterial hypertension (PAH).

METHODS

The medical records of 103 pregnant women with PAH admitted to Beijing Anzhen Hospital from January 2007 to March 2011 were studied retrospectively.

RESULTS

(1) Degree of PAH and cardiac function. Among the 103 PAH, 92 cases were patients with congenital heart disease and 13 cases were with rheumatic heart disease. They were divided by color doppler ultrasound into mild PAH group (34 cases), moderate PAH group (22 cases) and severe PAH group (47 cases). Per heart function classification, 21 cases (20.4%, 21/103) were class I, 44 cases (42.7%, 44/103) were class II, 27 cases (26.2%, 27/103) were class III and 11 cases (10.7%, 11/103) were class IV. More patients were class III and IV cardiac function in the severe PAH group than in the mild and moderate PAH groups, with statistically significant difference (P < 0.05). (2) Delivery mode. There were 44 term delivery and 23 preterm birth in the 103 PAH patients.Sixty-three cases (94%, 63/67) received cesarean section and 4 cases had vaginal delivery. There were 36 iatrogenic abortion (35.0%, 36/103). The iatrogenic abortion rate in the severe PAH group was significantly higher than those in the mild and moderate PAH groups (P < 0.05).(3) Perinatal outcomes. The full-term delivery rates in the mild and moderate PAH groups [80% (20/25) and 14/17] were significantly higher than the severe PAH group (40%, 10/25), respectively (P < 0.05). And the premature birth rate of the severe PAH group(60%, 15/25) was significantly higher than the mild and moderate PAH group [20% (5/25) and 3/17, P < 0.05]. There were 4 neonatal asphyxia. The birth weight of mild, moderate and severe PAH groups were (3071 ± 443), (2910 ± 619) and (2381 ± 589) g, respectively. The birth weight in the severe PAH group was significantly lower than the mild and moderate PAH groups (P < 0.05). (4) Mortality. Nine cases maternal death happened, with a mortality of 8.7% (9/103). All of them were severe pulmonary hypertension patients.

CONCLUSIONS

PAH is a serious complication during pregnancy.Women with mild PAH and normal cardiac function could continue pregnancy to full-term.Women with moderate PAH might continue pregnancy to 32 weeks under intensive care, cesarean delivery is preferable. Pregnant women with severe PAH should terminate pregnancy because of the high mortality.

Effectiveness of spironolactone plus ambrisentan for treatment of pulmonary arterial hypertension (from the [ARIES] study 1 and 2 trials)

In translational models of pulmonary arterial hypertension (PAH), spironolactone improves cardiopulmonary hemodynamics by attenuating the adverse effects of hyperaldosteronism on endothelin type-B receptor function in pulmonary endothelial cells. This observation suggests that coupling spironolactone with inhibition of endothelin type-A receptor-mediated pulmonary vasoconstriction may be a useful treatment strategy for patients with PAH. We examined clinical data from patients randomized to placebo or the selective endothelin type-A receptor antagonist ambrisentan (10 mg/day) and in whom spironolactone use was reported during ARIES-1 and -2, which were randomized, double-blind, placebo-controlled trials assessing the effect of ambrisentan for 12 weeks on clinical outcome in PAH. From patients randomized to placebo (n = 132) or ambrisentan (n = 67), we identified concurrent spironolactone use in 21 (15.9%) and 10 (14.9%) patients, respectively. Compared with patients treated with ambrisentan alone (n = 57), therapy with ambrisentan + spironolactone improved change in 6-minute walk distance by 94% at week 12 (mean ± SE, +38.2 ± 8.1 vs +74.2 ± 27.4 m, p = 0.11), improved plasma B-type natriuretic peptide concentration by 1.7-fold (p = 0.08), and resulted in a 90% relative increase in the number of patients improving ≥1 World Health Organization functional class (p = 0.08). Progressive illness, PAH-associated hospitalizations, or death occurred as an end point for 5.3% of ambrisentan-treated patients; however, no patient treated with ambrisentan + spironolactone reached any of these end points. In conclusion, these pilot data suggest that coupling spironolactone and endothelin type-A receptor antagonism may be clinically beneficial in PAH. Prospective clinical trials are required to further characterize our findings.

Echocardiographic estimation of pulmonary arterial systolic pressure in acute heart failure. Prognostic implications

BACKGROUND

Prognostic implications of echocardiographic assessment of pulmonary hypertension (PH) in non-selected patients hospitalized for acute heart failure (AHF) are not clearly defined. The aim of this study was to evaluate the association between echocardiography-derived PH in AHF and 1-year all-cause mortality.

METHODS

We prospectively included 1210 consecutive patients admitted for AHF. Patients with significant heart valve disease were excluded. Pulmonary arterial systolic pressure (PASP) was estimated using transthoracic echocardiography during hospitalization (mean time after admission 96±24h). Patients were categorized as follows: non-measurable, normal PASP (PASP≤35mmHg), mild (PASP 36-45mmHg), moderate (PASP 46-60mmHg) and severe PH (PASP >60mmHg). The independent association between PASP and 1-year mortality was assessed with Cox regression analysis.

RESULTS

At 1-year follow-up, 232 (19.2%) deaths were registered. PASP was measured in 502 (41.6%) patients with a median of 46 [38-55] mmHg. The distribution of population was: 708 (58.5%), 76 (6.3%), 147 (12.1%), 190 (15.7%) and 89 (7.4%) for non-measurable, normal PASP, mild, moderate and severe PH, respectively. One-year mortality was lower for patients with normal PASP (1.32 per 10 person-years), intermediate for patients with non-measurable, mild and moderate PH (2.48, 2.46 and 2.62 per 10 persons-year, respectively) and higher for those with severe PH (4.89 per 10 person-years). After multivariate adjustment, only patients with PASP >60mmHg displayed significant adjusted increase in the risk of 1-year all-cause mortality, compared to patients with normal PASP (HR=2.56; CI 95%: 1.05-6.22, p=0.038).

CONCLUSIONS

In AHF, severe pulmonary hypertension derived by echocardiography is an independent predictor of 1-year-mortality.

[Pregnancy in pulmonary arterial hypertension patients]

Pulmonary arterial hypertension (PAH) is a disorder defined by elevated mean pulmonary arterial pressure. PAH can be idiopathic or associated with a variety of medical conditions such as scleroderma, congenital heart disease, left heart failure, lung disease or chronic pulmonary thromboembolism. This progressive disease can cause severe right heart failure and death. Normal physiologic changes that occur during pregnancy may produce fatal consequences in PAH patients. Current guidelines recommend that pregnancy be avoided or terminated early in women with PAH. During the past decade, new advanced therapies for PAH have emerged gathering reports of successful pregnancies in patients with pulmonary hypertension. Substantial risk still exists and current recommendations have not changed. Nevertheless, in selected cases, if a patient insists on continuing the pregnancy, being fully aware of the risks involved, an intensive treatment approach should be implemented in experienced centers. This is necessary in order to control pulmonary hypertension during pregnancy and reduce the risk so as to improve outcomes. This review will focus on the pathophysiology of PAH in pregnancy and appropriate management during pregnancy, delivery and the post-partum period.

Macitentan and morbidity and mortality in pulmonary arterial hypertension

BACKGROUND

Current therapies for pulmonary arterial hypertension have been adopted on the basis of short-term trials with exercise capacity as the primary end point. We assessed the efficacy of macitentan, a new dual endothelin-receptor antagonist, using a primary end point of morbidity and mortality in a long-term trial.

METHODS

We randomly assigned patients with symptomatic pulmonary arterial hypertension to receive placebo once daily, macitentan at a once-daily dose of 3 mg, or macitentan at a once-daily dose of 10 mg. Stable use of oral or inhaled therapy for pulmonary arterial hypertension, other than endothelin-receptor antagonists, was allowed at study entry. The primary end point was the time from the initiation of treatment to the first occurrence of a composite end point of death, atrial septostomy, lung transplantation, initiation of treatment with intravenous or subcutaneous prostanoids, or worsening of pulmonary arterial hypertension.

RESULTS

A total of 250 patients were randomly assigned to placebo, 250 to the 3-mg macitentan dose, and 242 to the 10-mg macitentan dose. The primary end point occurred in 46.4%, 38.0%, and 31.4% of the patients in these groups, respectively. The hazard ratio for the 3-mg macitentan dose as compared with placebo was 0.70 (97.5% confidence interval [CI], 0.52 to 0.96; P=0.01), and the hazard ratio for the 10-mg macitentan dose as compared with placebo was 0.55 (97.5% CI, 0.39 to 0.76; P<0.001). Worsening of pulmonary arterial hypertension was the most frequent primary end-point event. The effect of macitentan on this end point was observed regardless of whether the patient was receiving therapy for pulmonary arterial hypertension at baseline. Adverse events more frequently associated with macitentan than with placebo were headache, nasopharyngitis, and anemia.

CONCLUSIONS

Macitentan significantly reduced morbidity and mortality among patients with pulmonary arterial hypertension in this event-driven study. (Funded by Actelion Pharmaceuticals; SERAPHIN ClinicalTrials.gov number, NCT00660179.).

Pulmonary arterial hypertension: use of delayed contrast-enhanced cardiovascular magnetic resonance in risk assessment

Background

Pulmonary arterial hypertension is a severe and progressive disease. Its early diagnosis is the greatest clinical challenge.

Objective

To evaluate the presence and extension of the delayed myocardial contrast-enhanced cardiovascular magnetic resonance, as well as to verify if the percentage of the myocardial fibrosis mass is a severity predictor.

Methods

Cross-sectional study with 30 patients with pulmonary arterial hypertension of groups I and IV, subjected to clinical, functional and hemodynamic evaluation, and to cardiac magnetic resonance.

Results

The mean age of patients was 52 years old, with female predominance (77%). Among the patients, 53% had right ventricular failure at diagnosis, and 90% were in functional class II/III. The mean of the 6-minute walk test was 395m. In hemodynamic study with right catheterism, the mean average pulmonary arterial pressure was 53.3mmHg, of the cardiac index of 2.1L/ min.m², and median right atrial pressure was 13.5 mmHg. Delayed myocardial contrast enhanced cardiovascular magnetic resonance was found in 28 patients. The mean fibrosis mass was 9.9 g and the median percentage of fibrosis mass was 6.17%. The presence of functional class IV, right ventricular failure at diagnosis, 6-minute walk test < 300 meters and right atrial pressure ≥ 15 mmHg, with cardiac index < 2.0 L/ min.m², there was a relevant association with the increased percentage of myocardial fibrosis.

Conclusion

The percentage of the myocardial fibrosis mass indicates a non-invasive marker with promising perspectives in identifying patients with high risk factors for pulmonary hypertension.

Echocardiographic parameters in patients with pulmonary arterial hypertension: correlations with right ventricular ejection fraction derived from cardiac magnetic resonance and hemodynamics

BACKGROUND

Echocardiography is the most convenient method used to evaluate right ventricular function, and several echocardiographic parameters were studied in previous studies. But the value of these parameters to assess the right ventricular function in patients with pulmonary arterial hypertension (PAH) has not been well defined.

METHODS

Patients with PAH were observed prospectively. Right heart catheterization, echocardiography and cardiac magnetic resonance (CMR) were performed within 1 week interval. The correlations between echocardiographic parameters and right ventricular ejection fraction (RVEF) derived from CMR as well as hemodynamics were analyzed.

RESULTS

Thirty patients were enrolled including 24 with idiopathic PAH, 5 with PAH associated with connective tissue diseases and 1 with hereditary PAH. All echocardiographic parameters except right ventricular myocardial performance index (RVMPI) correlated significantly with RVEF (tricuspid annual plane systolic excursion [TAPSE], r = 0.440, P = 0.015; tricuspid annular systolic excursion velocity [S'], r = 0.444, P = 0.016; isovolumic acceleration [IVA], r = 0.600, P = 0.001; right ventricular fraction area change [RVFAC], r = 0.416, P = 0.022; ratio of right ventricular transverse diameter to left ventricular transverse diameter [RVETD/LVETD], r = -0.649, P<0.001; RVMPI, r = -0.027, P = 0.888). After adjusted for mean right atrial pressure, mean pulmonary arterial pressure and pulmonary vascular resistance (PVR), only IVA and RVETD/LVETD could independently predict RVEF. Four echocardiographic parameters displayed significant correlations with PVR (TAPSE, r = -0.615, P<0.001; S', r = -0.557, P = 0.002; RVFAC, r = -0.454, P = 0.012; RVETD/LVETD, r = 0.543, P = 0.002).

CONCLUSIONS

The echocardiographic parameters IVA and RVETD/LVETD can reflect RVEF independently regardless of hemodynamics in patients with PAH. In addition, TAPSE, S', RVFAC and RVETD/LVETD can also reflect PVR in PAH patients.

Tadalafil for benign prostatic hyperplasia

Tadalafil is a phosphodiesterase type-5 (PDE5) inhibitor licensed for the treatment of erectile dysfunction (ED) in adult males (Cialis-Lilly) and for the management of pulmonary arterial hypertension (Adcirca-Lilly).(1) The 5mg tablet was licensed in November 2012 for the treatment of the signs and symptoms of benign prostatic hyperplasia (BPH) in adult males (Cialis 5mg-Lilly).(2) In this article, we consider the evidence for tadalafil and how its use fits with current management strategies for BPH.

Heme oxygenase-1 and inflammation in experimental right ventricular failure on prolonged overcirculation-induced pulmonary hypertension

Heme oxygenase (HO)-1 is a stress response enzyme which presents with cardiovascular protective and anti-inflammatory properties. Six-month chronic overcirculation-induced pulmonary arterial hypertension (PAH) in piglets has been previously reported as a model of right ventricular (RV) failure related to the RV activation of apoptotic and inflammatory processes. We hypothesized that altered HO-1 signalling could be involved in both pulmonary vascular and RV changes. Fifteen growing piglets were assigned to a sham operation (n = 8) or to an anastomosis of the left innominate artery to the pulmonary arterial trunk (n = 7). Six months later, hemodynamics was evaluated after closure of the shunt. After euthanasia of the animals, pulmonary and myocardial tissue was sampled for pathobiological evaluation. Prolonged shunting was associated with a tendency to decreased pulmonary gene and protein expressions of HO-1, while pulmonary gene expressions of interleukin (IL)-33, IL-19, intercellular adhesion molecule (ICAM)-1 and -2 were increased. Pulmonary expressions of constitutive HO-2 and pro-inflammatory tumor necrosis factor (TNF)-α remained unchanged. Pulmonary vascular resistance (evaluated by pressure/flow plots) was inversely correlated to pulmonary HO-1 protein and IL-19 gene expressions, and correlated to pulmonary ICAM-1 gene expression. Pulmonary arteriolar medial thickness and PVR were inversely correlated to pulmonary IL-19 expression. RV expression of HO-1 was decreased, while RV gene expressions TNF-α and ICAM-2 were increased. There was a correlation between RV ratio of end-systolic to pulmonary arterial elastances and RV HO-1 expression. These results suggest that downregulation of HO-1 is associated to PAH and RV failure.

A novel channelopathy in pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension is a devastating disease with high mortality. Familial cases of pulmonary arterial hypertension are usually characterized by autosomal dominant transmission with reduced penetrance, and some familial cases have unknown genetic causes.

METHODS

We studied a family in which multiple members had pulmonary arterial hypertension without identifiable mutations in any of the genes known to be associated with the disease, including BMPR2, ALK1, ENG, SMAD9, and CAV1. Three family members were studied with whole-exome sequencing. Additional patients with familial or idiopathic pulmonary arterial hypertension were screened for the mutations in the gene that was identified on whole-exome sequencing. All variants were expressed in COS-7 cells, and channel function was studied by means of patch-clamp analysis.

RESULTS

We identified a novel heterozygous missense variant c.608 G→A (G203D) in KCNK3 (the gene encoding potassium channel subfamily K, member 3) as a disease-causing candidate gene in the family. Five additional heterozygous missense variants in KCNK3 were independently identified in 92 unrelated patients with familial pulmonary arterial hypertension and 230 patients with idiopathic pulmonary arterial hypertension. We used in silico bioinformatic tools to predict that all six novel variants would be damaging. Electrophysiological studies of the channel indicated that all these missense mutations resulted in loss of function, and the reduction in the potassium-channel current was remedied by the application of the phospholipase inhibitor ONO-RS-082.

CONCLUSIONS

Our study identified the association of a novel gene, KCNK3, with familial and idiopathic pulmonary arterial hypertension. Mutations in this gene produced reduced potassium-channel current, which was successfully remedied by pharmacologic manipulation. (Funded by the National Institutes of Health.)

An oversized allograft is associated with improved survival after lung transplantation for idiopathic pulmonary arterial hypertension

BACKGROUND

Idiopathic pulmonary arterial hypertension (IPAH) is associated with high short-term mortality after bilateral lung transplantation (BLT). Previous studies have suggested that oversized allografts are associated with improved outcomes and that this association was strongest within the first year after transplant. We hypothesized that oversizing the allograft is associated with improved survival after BLT for IPAH.

METHODS

All adults in the United Network of Organ Sharing lung transplant registry who underwent first-time BLT for IPAH between October 1989 and April 2010 were studied. Lung size mismatch was assessed by calculating the predicted total lung capacity (pTLC) ratio of the donor to the recipient. The cohort was divided evenly into "undersized" (pTLC ratio less than the median pTLC ratio) and "oversized" (pTLC ratio exceeding the median pTLC ratio). Risk of death after BLT was analyzed using Kaplan-Meier survival and Cox proportional hazards models.

RESULTS

The mean pTLC ratio was 0.93 ± 0.10 in the 302 undersized patients compared with 1.24 ± 0.14 in the 302 oversized patients. Cohorts had comparable baseline characteristics. Median survival was 831 days longer in the oversized cohort (2,166 vs. 1,335 days, p = 0.006). In a multivariate model controlling for sex mismatch, recipient factors, acuity, donor factors, and transplant factors, oversizing was associated with decreased hazard for death at 5 years (hazard ratio, 0.73; 95% CI 0.56-0.96, p = 0.02).

CONCLUSION

Oversizing the allograft is associated with improved survival after BLT for IPAH. In the setting of donor organ shortages and waiting list mortality, it is not practical to intentionally oversize the allograft. However, the pTLC ratio could provide further refinement in the peri-transplant risk assessment.