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Elizabeth Ashley Hardin,1 Kelly M Chin2 1Department of Internal Medicine, Division of Cardiology, 2Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA Abstract: Pulmonary arterial hypertension is characterized by abnormalities in the small pulmonary arteries including increased vasoconstriction, vascular remodeling, proliferation of smooth muscle cells, and in situ thrombosis. Selexipag, a novel, oral prostacyclin receptor agonist, has been shown to improve hemodynamics in a phase II clinical trial and reduce clinical worsening in a large phase III clinical trial involving patients with pulmonary arterial hypertension. In this paper, we describe the prostacyclin signaling pathway, currently available oral prostanoid medications, and the development and clinical use of selexipag. Keywords: selexipag, pulmonary arterial hypertension, prostacyclin

Background: This study evaluated long-term outcomes in patients with pulmonary arterial hypertension (PAH) undergoing treatment with ambrisentan monotherapy, a selective oral endothelin-1 receptor antagonist.Methods and Results: Patients who participated in the Ambrisentan in Pulmonary Arterial Hypertension: A Phase 3, Randomized, Double-Blind, Placebo-Controlled Multicenter Efficacy Study (ARIES-1) clinical trial and extension phase at our institution were included. Cardiac catheterization, 6-minute walk distance (6MWD), and cardiac magnetic resonance (MRI) data were retrospectively reviewed. Twelve patients with PAH (11 idiopathic, 1 fenfluramine) had follow-up from 3 to 5.5 years from the initiation of ARIES-1. Patients received ambrisentan therapy throughout the study period and were on ambrisentan monotherapy for the first 2 years. At year 1, improvements in median mean pulmonary arterial pressure (PA), cardiac output, and pulmonary vascular resistance (PVR) were seen (P = .02, P = .03, P < .01), and the improvement in PVR persisted at 2 years. 6MWD also improved significantly between baseline (350 m) and 1 and 2 years (397 m, P < .01 and 393 m, P = .01). Cardiac MRI results were more varied, with an increase in RV ejection fraction from 29% at baseline to 46% at 2 years (P = .02), but other MRI variables did not improve.Conclusions: Ambrisentan monotherapy led to improvements in catheterization, 6MWD, and RV ejection fraction, and shows promise as a long-term treatment for pulmonary arterial hypertension. [ABSTRACT FROM AUTHOR]

Rationale: Heterozygous mutations in the coding regions of the telomerase genes, TERT and TERC, have been found in familial and sporadic cases of idiopathic interstitial pneumonia. All affected patients with mutations have short telomeres.Objectives: To test whether telomere shortening is a frequent mechanism underlying pulmonary fibrosis, we have characterized telomere lengths in subjects with familial or sporadic disease who do not have coding mutations in TERT or TERC.Methods: Using a modified Southern blot assay, the telomerase restriction fragment length method, and a quantitative polymerase chain reaction assay we have measured telomere lengths of genomic DNA isolated from circulating leukocytes from normal control subjects and subjects with pulmonary fibrosis.Measurements and Main Results: All affected patients with telomerase mutations, including case subjects heterozygous for newly reported mutations in TERT, have short telomere lengths. A significantly higher proportion of probands with familial pulmonary fibrosis (24%) and sporadic case subjects (23%) in which no coding mutation in TERT or TERC was found had telomere lengths less than the 10th percentile when compared with control subjects (P = 2.6 x 10(-8)). Pulmonary fibrosis affectation status was significantly associated with telomerase restriction fragment lengths, even after controlling for age, sex, and ethnicity (P = 6.1 x 10(-11)). Overall, 25% of sporadic cases and 37% of familial cases of pulmonary fibrosis had telomere lengths less than the 10th percentile.Conclusions: A significant fraction of individuals with pulmonary fibrosis have short telomere lengths that cannot be explained by coding mutations in telomerase. Telomere shortening of circulating leukocytes may be a marker for an increased predisposition toward the development of this age-associated disease. [ABSTRACT FROM AUTHOR]

BACKGROUND: IV epoprostenol is a highly effective therapy for pulmonary arterial hypertension (PAH). However, monitoring the efficacy and adjusting the dose of epoprostenol often requires serial invasive hemodynamic measurements. This study investigated whether superior vena cava (SVC) oxygen saturation measured from the indwelling catheter and brain natriuretic peptide (BNP) level would predict right heart catheterization markers associated with lower survival rates (right atrial pressure [RAP], > 10 mm Hg; pulmonary artery [PA] oxygen saturation, < 62%) in epoprostenol-treated patients with PAH. METHODS: Twenty-seven epoprostenol-treated PAH patients had a BNP level and SVC oxygen saturation measured from their indwelling central venous catheters. The results were compared with cardiac catheterization results. RESULTS: SVC oxygen saturation and BNP level both showed significant correlation with hemodynamic variables. BNP level correlated best with RAP (r = 0.66; p < 0.001), while SVC oxygen saturation correlated most closely with PA oxygen saturation (r = 0.91; p < 0.001). All patients with a BNP level of >or= 117 pg/mL had an elevated RAP (specificity, 100% [defined as a RAP of > 10 mm Hg]), but sensitivity was only 65%. An SVC oxygen saturation of < 64% showed a sensitivity of 89% and a specificity of 78% in predicting a PA oxygen saturation of < 62%. CONCLUSIONS: SVC oxygen saturation and BNP level predict hemodynamics associated with lower survival rates and may be useful as 'noninvasive' markers of prognosis in epoprostenol-treated PAH patients. BNP levels have a lower sensitivity relative to specificity, and a normal BNP level did not exclude a high RAP or low PA oxygen saturation. [ABSTRACT FROM AUTHOR]