The minimal important difference in the 6-minute walk test for patients with pulmonary arterial hypertension

Exercise intolerance in pulmonary hypertension: mechanism, evaluation and clinical implications

INTRODUCTION

Exercise intolerance in pulmonary hypertension (PH) is a major factor affecting activities of daily living and quality of life. Evaluation strategies (i.e., non-invasive and invasive tests) are integral to providing a comprehensive assessment of clinical and functional status. Despite a growing body of literature on the clinical consequences of PH, there are limited studies discussing the contribution of various physiological systems to exercise intolerance in this patient population.

AREAS COVERED

This review, through a search of various databases, describes the physiological basis for exercise intolerance across the various PH etiologies, highlights the various exercise evaluation methods and discusses the rationale for exercise training amongst those diagnosed with PH. Expert commentary: With the growing importance of evaluating exercise capacity in PH (class 1, Level C recommendation), understanding why exercise performance is altered in PH is crucial. Thus, the further study is required for better quality evidence in this area.

Rare pulmonary diseases and orphan drugs: where do we stand and where are we going to?

Rare diseases are a major problem for the patients who suffer from them, for their families and for selected specialists involved in their management. In addition, they cause economic, social and public health problems that should be acknowledged and discussed by the medical and scientific community. Because of the rarity of these illnesses, the experience of most physicians is usually limited to a few cases. Nevertheless, the essential steps in the diagnosis and management of a patient who is suspected to have, for example, an interstitial lung disease or pulmonary hypertension, should be common knowledge, as these diseases are uncommon, but not, in fact, exceedingly rare [1–3]. Furthermore, rare presentations of frequent lung diseases (e.g. rare thoracic cancers, severe asthma, and emphysema with α₁-antitrypsin deficiency) and the most typical rare pulmonary diseases can share similar aspects, both in research and in their clinical management [4].

Updates on rare pulmonary diseases from the 6th International Meeting on Pulmonary Rare Diseases and Orphan Drugshttp://ow.ly/PYUCC

Severity of pulmonary hypertension and obesity are not associated with worse functional outcomes after pulmonary thromboendarterectomy

Predictors of functional outcomes in patients with chronic thromboembolic pulmonary hypertension (CTEPH) undergoing pulmonary thromboendarterectomy (PTE) are important to identify preoperatively. We hypothesized that baseline severity of pulmonary hypertension and obesity would not be associated with 6-month functional outcomes after PTE. Clinical and hemodynamic data were collected on consecutive patients undergoing PTE from 2008 to 2014. Patients were stratified according to baseline pulmonary vascular resistance (PVR) and body mass index (BMI). Six-minute walk distance (6MWD), New York Heart Association functional class (FC), and echocardiography were assessed in each group at baseline and 6 months after PTE. Regression analyses were performed to evaluate for associations between functional outcomes and baseline PVR and BMI. Forty-two patients underwent PTE and had 6-month follow up data. In comparisons of patients with high and low baseline PVR, the baseline characteristics, distribution of disease, 6MWD, and FC were similar. Postoperative hemodynamics for both groups were similar. At 6 months, both groups achieved improvements in FC, and there were no between-group differences in the change in 6MWD or FC. In comparisons of obese and nonobese patients, perioperative and FC improvement were similar; however, obese patients achieved a greater improvement in 6MWD than nonobese patients (P = 0.04). In conclusion, our data suggest that baseline severity of CTEPH and obesity were not associated with worse functional outcome. Further studies are needed to confirm these results, as these findings could have implications for patient selection for PTE.

Riociguat for the treatment of pulmonary hypertension: Chinese subgroup analyses and comparison

OBJECTIVE

PATENT-1 and CHEST-1 were pivotal, international phase III trials assessing riociguat for pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Here we compare Chinese patients from these studies with the overall populations, and report the clinical effect and safety of riociguat in Chinese patients with PAH and CTEPH.

METHODS

PATENT-1 was a 12-week, randomised, double-blind, placebo-controlled trial of riociguat (maximum 2.5 mg three times daily or 1.5 mg three times daily (exploratory) in patients with PAH. CHEST-1 was a 16-week, randomised, double-blind, placebo-controlled trial of riociguat (maximum 2.5 mg three times daily) in patients with inoperable CTEPH or persistent/recurrent pulmonary hypertension after pulmonary endarterectomy. The primary endpoint in each study was change from baseline to study end in 6 min walking distance (6MWD). Secondary endpoints included pulmonary vascular resistance (PVR), N-terminal prohormone of brain natriuretic peptide, WHO functional class (FC), and time to clinical worsening.

RESULTS

Chinese patients in PATENT-1 (n=77) and CHEST-1 (n=32) were younger and had better baseline 6MWD and WHO FC versus the overall population. Riociguat increased 6MWD versus placebo in Chinese patients in PATENT-1 and CHEST-1, with a greater increase observed in CHEST-1 (least-squares mean differences +46 m and +102 m in PATENT-1 and CHEST-1, respectively). Riociguat also improved several secondary endpoints in both studies, and was well tolerated.

CONCLUSIONS

Chinese patients displayed differences in baseline characteristics versus the overall populations in PATENT-1 and CHEST-1. Riociguat improved 6MWD, PVR, WHO FC, and other clinical outcomes in Chinese patients with PAH or CTEPH.

TRIAL REGISTRATION NUMBER

PATENT-1: NCT00810693, Results; CHEST-1 NCT00855465, Results.

Ambrisentan and Tadalafil Up-front Combination Therapy in Scleroderma-associated Pulmonary Arterial Hypertension

BACKGROUND

Scleroderma-associated pulmonary arterial hypertension (SSc-PAH) is a rare disease characterized by a very dismal response to therapy and poor survival. We assessed the effects of up-front combination PAH therapy in patients with SSc-PAH.

METHODS

In this prospective, multicenter, open-label trial, 24 treatment-naive patients with SSc-PAH received ambrisentan 10 mg and tadalafil 40 mg daily for 36 weeks. Functional, hemodynamic, and imaging (cardiac magnetic resonance imaging and echocardiography) assessments at baseline and 36 weeks included changes in right ventricular (RV) mass and pulmonary vascular resistance as co-primary endpoints and stroke volume/pulmonary pulse pressure ratio, tricuspid annular plane systolic excursion, 6-minute walk distance, and N-terminal pro-brain natriuretic peptide as secondary endpoints.

RESULTS

At 36 weeks, we found that treatment had resulted in significant reductions in median (interquartile range [IQR]) RV mass (28.0 g [IQR, 20.6-32.9] vs. 32.5 g [IQR, 23.2-41.4]; P < 0.05) and median pulmonary vascular resistance (3.1 Wood units [IQR, 2.0-5.7] vs. 6.9 Wood units [IQR, 4.0-12.9]; P < 0.0001) and in improvements in median stroke volume/pulmonary pulse pressure ratio (2.6 ml/mm Hg [IQR, 1.8-3.5] vs. 1.4 ml/mm Hg [IQR 8.9-2.4]; P < 0.0001) and mean ( ± SD) tricuspid annular plane systolic excursion (2.2 ± 0.12 cm vs. 1.65 ± 0.11 cm; P < 0.0001), 6-minute walk distance (395 ± 99 m vs. 343 ± 131 m; P = 0.001), and serum N-terminal pro-brain natriuretic peptide (647 ± 1,127 pg/ml vs. 1,578 ± 2,647 pg/ml; P < 0.05).

CONCLUSIONS

Up-front combination therapy with ambrisentan and tadalafil significantly improved hemodynamics, RV structure and function, and functional status in treatment-naive patients with SSc-PAH and may represent a very effective therapy for this patient population. In addition, we identified novel hemodynamic and imaging biomarkers that could have potential value in future clinical trials. Clinical trial registered with www.clinicaltrials.gov (NCT01042158).

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.

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

BACKGROUND

Pulmonary arterial hypertension is a chronic disease associated with poor long-term outcomes. Identifying predictors of long-term outcome in pulmonary arterial hypertension is important to assess disease severity and guide treatment. We investigate associations between efficacy parameters and long-term outcomes in patients with pulmonary arterial hypertension receiving riociguat in the PATENT-2 study. We also present safety and efficacy data from the final data cutoff of PATENT-2, where most patients had received at least 2 years of riociguat treatment.

METHODS

Eligible patients from the PATENT-1 study entered the PATENT-2 open-label extension, which will continue until all patients transition to the commercial drug. All patients received riociguat individually adjusted to a maximum dose of 2·5 mg three times a day. The primary endpoint was safety and tolerability, assessed with recording adverse events, serious adverse events, discontinuations, and deaths; exploratory assessments included 6-min walking distance (6MWD), WHO functional class, N-terminal prohormone of brain natriuretic peptide (NT-proBNP)concentrations, Borg dyspnoea score, health-related quality of life (EQ-5D score), survival, and clinical worsening-free survival. Association between efficacy parameters and long-term outcomes was assessed using Kaplan-Meier analyses and a Cox proportional-hazards regression model. PATENT-2 is registered at ClinicalTrials.gov, number NCT00863681.

FINDINGS

396 patients entered PATENT-2, of whom 197 patients were receiving riociguat monotherapy and 199 were receiving riociguat in combination with endothelin receptor antagonists or prostanoids, or both. A significant association was noted between 6MWD, NT-proBNP concentration, and WHO functional class and overall survival at baseline (p=0·0006, 0·0225, and 0·0191, respectively), and at follow-up (p=0·021, 0·0056, and 0·0048, respectively). Riociguat was well tolerated in PATENT-2. Serious adverse events were recorded in 238 (60%) of the total population, and 45 (11%) patients discontinued treatment because of an adverse event. Improvements in 6MWD, WHO functional class, and NT-proBNP concentrations were maintained after 2 years of treatment.

INTERPRETATION

These results support the long-term use of riociguat in patients with pulmonary arterial hypertension, and emphasise the prognostic value of 6MWD, WHO functional class, and NT-proBNP concentrations.

FUNDING

Bayer Pharma AG.

Endothelin-1 Pathway Polymorphisms and Outcomes in Pulmonary Arterial Hypertension

RATIONALE

Pulmonary arterial hypertension (PAH) is a progressive fatal disease. Variable response and tolerability to PAH therapeutics suggests that genetic differences may influence outcomes. The endothelin pathway is central to pulmonary vascular function, and several polymorphisms and/or mutations in the genes coding for endothelin (ET)-1 and its receptors correlate with the clinical manifestations of other diseases.

OBJECTIVES

To examine the interaction of ET-1 pathway polymorphisms and treatment responses of patients with PAH treated with ET receptor antagonists (ERAs).

METHODS

A total of 1,198 patients with PAH were prospectively enrolled from 45 U.S. and Canadian pulmonary hypertension centers or retrospectively from global sites participating in the STRIDE (Sitaxsentan To Relieve Impaired Exercise) trials. Comprehensive objective measures including a 6-minute-walk test, Borg dyspnea score, functional class, and laboratory studies were completed at baseline, before the initiation of ERAs, and repeated serially. Single-nucleotide polymorphisms from ET-1 pathway candidate genes were selected from a completed genome-wide association study performed on the study cohort.

MEASUREMENTS AND MAIN RESULTS

Patient efficacy outcomes were analyzed for a relationship between ET-1 pathway polymorphisms and clinical efficacy using predefined, composite positive and negative outcome measures in 715 European descent samples. A single-nucleotide polymorphism (rs11157866) in the G-protein alpha and gamma subunits gene was significantly associated, accounting for multiple testing, with a combined improvement in functional class and 6-minute-walk distance at 12 and 18 months and marginally significant at 24 months.

CONCLUSIONS

ET-1 pathway associated polymorphisms may influence the clinical efficacy of ERA therapy for PAH. Further prospective studies are needed.

Riociguat: a novel new drug for treatment of pulmonary hypertension

Riociguat is the first approved medication from the novel class of soluble guanylate cyclase (sGC) stimulators and the only agent approved for treating both chronic thromboembolic hypertension (CTEPH) and pulmonary arterial hypertension (PAH). The novel mechanism of riociguat lies in its ability to restore the homeostatic and therapeutic effects of nitric oxide that are diminished as a result of phenotypic alterations associated with pulmonary hypertension (PH). Improvements in 6-minute walk distance (6MWD) in patients with PAH during the phase 3 PATENT-1 trial were comparable to other oral agents approved for the treatment of PAH. Improvements in 6MWD in patients with CTEPH during the phase 3 CHEST-1 trial were greater than those previously observed with other oral PAH-directed therapies. Hypotension is the dose-limiting adverse effect of riociguat and dose titration is performed gradually according to systolic blood pressure. Riociguat was tolerated at maximal doses by most patients during PATENT-1 and CHEST-1 and was well tolerated during long-term extension studies. Key factors to consider with riociguat are a patient's systolic blood pressure, drug interactions mediated by CYP1A1, CYP3A4, and P-glycoprotein, cost, and teratogenicity requiring enrollment in a Risk Evaluation and Mitigation Strategy program. Recently published guidelines recommend riociguat monotherapy as an option for treatment-naïve patients with World Health Organization Functional Class (WHO FC) II or III symptoms or as add-on therapy for patients with persistent WHO FC III or IV symptoms being treated with an ERA or inhaled prostanoid. Postmarketing experience and ongoing clinical investigations will further define the safety and role of riociguat in patients with PAH and other types of PH.

Effects of Exercise Training on Exercise Capacity in Pulmonary Arterial Hypertension: A Systematic Review of Clinical Trials

BACKGROUND

Pulmonary arterial hypertension (PAH) causes profound functional limitations and poor quality of life. Yet, there is only a limited literature available on the role of exercise training. This paper systematically reviews the effects of exercise training on exercise capacity in PAH.

METHODS

A systematic search of databases (PubMed, CINAHL, CENTRAL, Web of Science and PEDRo) was undertaken for English language articles published between 1(st) January 1980 and 31(st) March 2015. Quality rating for all articles was done using the Downs and Black scoring system.

RESULTS

Fifteen articles of good (n=4), moderate (n=6) and poor (n=5) quality were included in the review. Exercise interventions included aerobic, resistance, inspiratory muscle training or a combination, for 6-18 weeks. Improvements were seen in exercise capacity (six minute walk distance (6MWD) and peak VO2) by 17-96m and 1.1-2.1ml/Kg/min, functional class by one class and quality of life, with minimal adverse events.

CONCLUSIONS

There is evidence to recommend the use of exercise training as an adjunct to medical treatment in PAH. More clinical trials and research are required to assess the effects of different types of exercise programs in patients with PAH, while focussing on strong exercise endpoints to quantify the improvements seen with exercise training.

The minimal important difference of the epistaxis severity score in hereditary hemorrhagic telangiectasia

OBJECTIVES/HYPOTHESIS

Hereditary hemorrhagic telangiectasia (HHT) is a disease of abnormal angiogenesis, causing epistaxis in over 96% of patients. The Epistaxis Severity Score (ESS) was developed as a standardized measurement of nasal symptoms among HHT patients. The minimal important difference (MID) of a disease index estimates the smallest change that a patient and clinician would identify as important. This study aims to establish the MID of the ESS in a diverse population of HHT patients.

STUDY DESIGN

Retrospective cross-sectional study in patients with a diagnosis of HHT using Curacao criteria or genetic testing.

METHODS

The ESS questionnaire and Medical Outcomes Study 36-Item Short Form (SF-36) were administered to participants recruited through the HHT Foundation Web site. Demographics and relevant medical histories were collected from all participants. An anchor-based method using a change of 5 in the Physical Component Summary (PCS) of the SF-36 and a distributional method were used to estimate the MID.

RESULTS

A total of 604 subjects were recruited between April and August 2008. All participants reported epistaxis. An increasing ESS in the study cohort showed a significant negative correlation to the PCS (r = -0.43, P < 0.001). The MID was determined to be 0.41 via the anchor-based approach and 1.01 via the distribution-based approach, giving a mean MID of 0.71.

CONCLUSION

Using both the anchor-based and distribution-based approaches, the estimated MID for the ESS in HHT is 0.71. Further implications include key metrics to help guide treatment responses in clinical care and essential information to calculate power and sample size for future clinical trials.

LEVEL OF EVIDENCE

4. Laryngoscope, 126:1029-1032, 2016.

Use of outcome measures in pulmonary hypertension clinical trials

OBJECTIVES

To evaluate the use of surrogate measures in pulmonary hypertension (PH) clinical trials and how it relates to clinical practice.

BACKGROUND

Studies of pulmonary arterial hypertension (PAH) employ a variety of surrogate measures in addition to clinical events because of a small patient population, participant burden, and costs. The use of these measures in PH drug trials is poorly defined.

METHODS

We searched PubMed/MEDLINE/Embase for randomized or prospective cohort PAH clinical treatment trials from 1985 to 2013. Extracted data included intervention, trial duration, study design, patient characteristics, and primary and secondary outcome measures. To compare with clinical practice, we assessed the use of surrogate measures in a clinical sample of patients on PH medications at Duke University Medical Center between 2003 and 2014.

RESULTS

Between 1985 and 2013, 126 PAH trials were identified and analyzed. Surrogate measures served as primary endpoints in 119 trials (94.0%). Inclusion of invasive hemodynamics decreased over time (78.6%, 75.0%, 52.2%; P for trend = .02), while functional testing (7.1%, 60.0%, 81.5%; P for trend < .0001) and functional status or quality of life (0%, 47.6%, 62.8%; P for trend < .0001) increased in PAH trials over the same time periods. Echocardiography data were reported as a primary or secondary outcome in 32 trials (25.4%) with increased use from 1985-1994 to 1995-2004 (7.1% vs 35.0%, P = .04), but the trend did not continue to 2005-2013 (25.0%). In comparison, among 450 patients on PAH therapies at our institution between 2003 and 2013, clinical assessments regularly incorporated serial echocardiography and 6-minute walk distance tests (92% and 95% of patients, respectively) and repeat measurement of invasive hemodynamics (46% of patients).

CONCLUSIONS

The majority of PAH trials have utilized surrogate measures as primary endpoints. The use of these surrogate endpoints has evolved significantly over time with increasing use of patient-centered endpoints and decreasing or stable use of imaging and invasive measures. In contrast, imaging and invasive measures are commonly used in contemporary clinical practice. Further research is needed to validate and standardize currently used measures.

Pulmonary arterial hypertension: a review in pharmacotherapy

Pulmonary arterial hypertension (PAH) is a progressive disease that remains incurable. The past 2 decades have witnessed many advances in PAH-directed therapies. More recently, 3 new oral agents have become available in the United States within the past 2 years. Treprostinil is now available in extended-release oral tablets. Macitentan is the third endothelin receptor antagonist approved for use, demonstrating benefits on morbidity and mortality among patients with PAH in an event-driven study. Riociguat is the first soluble guanylate cyclase stimulator that has been approved for use in the United States. This article reviews the clinical efficacy and safety of these 3 agents and the roles they play in the management of PAH. Additionally, we review the limitations of using surrogate markers such as change in 6-minute walk distance to assess disease progression.

Riociguat for pulmonary arterial hypertension associated with congenital heart disease

Objective

The Pulmonary Arterial hyperTENsion sGC-stimulator Trial-1 (PATENT-1) was a randomised, double-blind, placebo-controlled phase III trial evaluating riociguat in patients with pulmonary arterial hypertension (PAH). PATENT-2 was an open-label long-term extension to PATENT-1. Here, we explore the efficacy and safety of riociguat in the subgroup of patients with persistent/recurrent PAH after correction of congenital heart disease (PAH-CHD) from the PATENT studies.

Methods

In PATENT-1, patients received riociguat (maximum 2.5 or 1.5 mg three times daily) or placebo for 12 weeks; efficacy assessments included change from baseline to study end in 6-min walking distance (6MWD; primary), pulmonary vascular resistance (PVR), N-terminal of the prohormone of brain natriuretic peptide (NT-proBNP), WHO functional class (WHO FC) and time to clinical worsening. In PATENT-2, eligible patients from PATENT-1 received long-term riociguat (maximum 2.5 mg three times daily); the primary assessment was safety and tolerability. All PAH-CHD patients had a corrected cardiac defect.

Results

In PATENT-1, riociguat increased mean±SD 6MWD from baseline to week 12 by 39±60 m in patients with PAH-CHD versus 0±42 m for placebo. Riociguat also improved several secondary variables versus placebo, including PVR (−250±410 vs −66±632 dyn·s/cm⁵), NT-proBNP (−164±317 vs −46±697 pg/mL) and WHO FC (21%/79%/0% vs 8%/83%/8% improved/stabilised/worsened). One patient experienced clinical worsening (riociguat 1.5 mg group). Riociguat was well tolerated. In PATENT-2, riociguat showed sustained efficacy and tolerability in patients with PAH-CHD at 2 years.

Conclusions

Riociguat was well tolerated in patients with PAH-CHD and improved clinical outcomes including 6MWD, PVR, WHO FC and NT-proBNP.

Trial registration number

The clinical trials numbers are NCT00810693 for PATENT-1 and NCT00863681 for PATENT-2.

Elosulfase Alfa: a review of its use in patients with mucopolysaccharidosis type IVA (Morquio A syndrome)

Elosulfase alfa (Vimizim(®)) is a recombinant form of the human lysosomal enzyme N-acetylgalactosamine-6-sulfatase (GALNS) that is lacking in patients with mucopolysaccharidosis type IVA (MPS IVA; Morquio A syndrome). It is the first, and currently only, disease-specific treatment option for this very rare, progressively degenerative, autosomal-recessive lysosomal storage disorder. Enzyme replacement therapy with elosulfase alfa aims to restore GALNS activity, thereby preventing the accumulation of keratan sulfate (KS) and chondroitin-6-sulfate in lysosomal compartments of cells that results in the clinical manifestations of MPS IVA. In clinical trials in children and adults with MPS IVA, intravenous elosulfase alfa 2 mg/kg/week provided significant and sustained improvements in urinary levels of KS (a pharmacodynamic biomarker for the disease). In the key placebo-controlled, 24-week, phase 3 trial in patients with MPS IVA aged ≥5 years, elosulfase alfa 2 mg/kg/week significantly improved endurance [least squares mean placebo-adjusted change from baseline in 6-min walk test distance 22.5 m (95 % CI 4.0-40.9)]. Infusion-associated reactions, the primary tolerability issue associated with elosulfase alfa, are generally mild to moderate in severity, self-limiting, and manageable. In the absence of a cure, GALNS enzyme replacement therapy with elosulfase alfa is an important achievement in the treatment of MPS IVA.

Monitoring and Diagnostic Approaches for Pulmonary Arterial Hypertension in Patients with Systemic Sclerosis

Pulmonary arterial hypertension (PAH) is one of the leading causes of death in patients with systemic sclerosis (SSc). Given the high prevalence and poor survival of SSc-PAH, and that aggressive management of mild disease may be associated with better outcomes, screening is critical. Right heart catheterization (RHC) is the gold standard for the definitive diagnosis of PAH, and should be performed in those patients in whom this diagnosis is suspected. Once a diagnosis of PAH is confirmed by RHC, treatment with PAH-specific therapies should be initiated as soon as possible.

Right ventricular wave reflection relate to clinical measures in pulmonary arterial hypertension

OBJECTIVES

When a forward running pressure wave from the right ventricle reaches the narrow vessels in the pulmonary circulation, it is reflected as a backward running wave. We aimed to relate changes in right ventricular waveform reflection (RVWR) to changes in clinical variables in pulmonary arterial hypertension (PAH) patients.

DESIGN

Twenty-one PAH patients with RV waveform recordings from two sequential catheterisations at least 6 months apart were included. Six-minute walked distance (6MWD) and brain natriuretic peptide (BNP) level were also available. RVWR was defined as 'the pressure from the inflection point on the upstroke RV pressure wave to RV peak pressure'. Direction of change in RVWR, 6MWD and BNP was classified as (+) if increased and (-) if decreased. Spearman correlations were used to analyse the relation between changes. Pearson's correlation coefficient was used to analyse relation between RVWR and pulmonary vascular resistance (PVR).

RESULTS

The correlation between change in RVWR and 6MWD was - 0.67 (p < 0.01) and between RVWR and BNP was - 0.53 (p < 0.05). Actual RVWR and PVR correlated both at first (0.56, p < 0.001) and at second right heart catheterisation (0.45, p < 0.001).

CONCLUSION

RVWR might have clinical implications indicating a change in clinical status and disease progression in patients with PAH.

Early decline in six-minute walk distance from the time of diagnosis predicts clinical worsening in pulmonary arterial hypertension

BACKGROUND

The six-minute walk distance (6MWD) is commonly used to assess pulmonary arterial hypertension (PAH). However, the role of 6MWD in predicting outcomes in PAH is controversial. Clinical worsening is being increasingly considered as a clinically meaningful end point in PAH.

OBJECTIVES

We aimed to investigate whether early longitudinal changes in 6MWD (Δ6MWD) in meters and percent predicted (%pred) from the time of diagnosis predict clinical worsening of PAH.

METHODS

One hundred patients with group I PAH were retrospectively assessed. 6MWD was calculated using American (%pred US) or Canadian (%pred CAN) reference equations. Δ6MWD at 6 months were recorded. Clinical worsening was defined as either: development of right heart failure, hospital admission for PAH, referral for lung transplantation or initiation of prostanoids after oral therapy failed. Optimal 6-month differences in 6MWD to detect worsening were defined with receiver operating characteristics (ROC) analysis.

RESULTS

Progressors, i.e. patients with clinical worsening, and nonprogressors showed significant differences in Δ6MWD. The most clinically significant declines in 6MWD at 6 months were ≥35 m, ≥8%pred US and ≥6%pred CAN. ROC and Cox proportional hazard analyses showed equivalent results for 6MWD %pred and meters. Six-month declines in 6MWD predicted worsening with a high specificity (94%) but a low sensitivity (33%).

CONCLUSIONS

Early declines in 6MWD (within the first 6 months) predict future clinical worsening of PAH with high specificity. Δ6MWD may still be part of a comprehensive assessment of a patient's clinical status. However, given the poor sensitivity, a decline in 6MWD should be used with other clinical tools to make an appropriate assessment of the progression of PAH.

Sex differences in response to tadalafil in pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is a progressive disease with high rates of morbidity and mortality. Current therapies improve symptoms, functional capacity, and, in select cases, survival. Little is known about patient factors that may predict the likelihood of patient-important, clinically relevant responses to therapy such as the 6-min walk distance (6MWD) and health-related quality of life (HRQoL).

METHODS

Data from the randomized clinical trial of tadalafil in PAH were used. Adjusted logistic regression models were created to examine the relationship between baseline characteristics and odds of achieving the minimal important difference (MID) in three parameters, defined as either a > 33-m increase in 6MWD, a > 5-unit increase in physical component summary score of the Medical Outcomes Study Short Form-36 (SF-36), or a > 5-unit increase in mental component summary score of the SF-36.

RESULTS

The study included 405 subjects. Younger age, male sex, lower baseline 6MWD, and disease etiology were associated with greater odds of achieving the MID for the 6-min walk test. Active treatment, younger age, and male sex were associated with greater odds of achieving the MID for the physical component summary score. Male sex was associated with greater odds of achieving the MID for the mental component summary score.

CONCLUSIONS

Age, sex, baseline functional capacity, and disease etiology are variably associated with the likelihood of achieving clinically relevant responses in patient-important outcomes to PAH-specific therapy such as 6MWD and HRQoL. The increased likelihood of response in men compared with women is a novel finding and may reflect pathophysiologic differences between sexes.

Six-minute walk test in pulmonary arterial hypertension

Exercise intolerance is the main characteristic of pulmonary arterial hypertension (PAH). The six-minute walk test (6MWT) and cardiopulmonary exercise test are widely used in assessing exercise capacity of PAH patients. Six-minute walk distance (6MWD) has been specified as the main clinical outcome in PAH and has been used as the primary end-point in many studies conducted for new PAH treatments. Using 6MWD as the end-point in clinical studies has many advantages. 6MWT is an inexpensive, easily applicable, and repeatable standardized test that is well-tolerated by PAH patients. Moreover, it is a valid measure of symptomatic improvement. It is correlated with variables of maximal cardiopulmonary exercise test as a measure of submaximal exercise capacity and disease severity markers such as functional class and pulmonary hemodynamics. It is widely used in clinical practice together with other invasive and non-invasive disease markers in assessing disease progression and response to treatment. In addition, it has prognostic importance and is a good prognostic marker. On the other hand, there are limitations to the use of 6MWD as the primary end-point in PAH treatment. It has decreased sensitivity in individuals with less severe disease and high 6MWD at baseline and decreased adequacy in assessing the effects of treatment in patients who are still under PAH treatment. Despite the limitations, 6MWD plays a key role in the evaluation and management of PAH patients.

Use of responder threshold criteria to evaluate the response to treatment in the phase III CHEST-1 study

BACKGROUND

In the Chronic Thromboembolic Pulmonary Hypertension Soluble Guanylate Cyclase - Stimulator Trial 1 (CHEST-1) study, riociguat improved 6-minute walking distance (6MWD) vs placebo in patients with inoperable chronic thromboembolic pulmonary hypertension or persistent/recurrent pulmonary hypertension after pulmonary endarterectomy. In this study, the proportion of patients who achieved responder thresholds that correlate with improved outcome in patients with pulmonary arterial hypertension was determined at baseline and at the end of CHEST-1.

METHODS

Patients received placebo or riociguat individually adjusted up to 2.5 mg 3 times a day for 16 weeks. Response criteria were defined as follows: 6MWD increase ≥40 m, 6MWD ≥380 m, cardiac index ≥2.5 liters/min/m(2), pulmonary vascular resistance <500 dyn∙sec∙cm(-5), mixed venous oxygen saturation ≥65%, World Health Organization functional class I/II, N-terminal pro-brain natriuretic peptide <1,800 pg/ml, and right atrial pressure <8 mm Hg.

RESULTS

Riociguat increased the proportion of patients with 6MWD ≥380 m, World Health Organization functional class I/II, and pulmonary vascular resistance <500 dyn∙sec∙cm(-5) from 37%, 34%, and 25% at baseline to 58%, 57%, and 50% at Week 16, whereas there was little change in placebo-treated patients (6MWD ≥380 m, 43% vs 44%; World Health Organization functional class I/II, 29% vs 38%; pulmonary vascular resistance <500 dyn∙sec∙cm(-5), 27% vs 26%). Similar changes were observed for thresholds for cardiac index, mixed venous oxygen saturation, N-terminal pro-brain natriuretic peptide, and right atrial pressure.

CONCLUSIONS

In this exploratory analysis, riociguat increased the proportion of patients with inoperable chronic thromboembolic pulmonary hypertension or persistent/recurrent pulmonary hypertension after pulmonary endarterectomy achieving criteria defining a positive response to therapy.

Use of clinically relevant responder threshold criteria to evaluate the response to treatment in the phase III PATENT-1 study

BACKGROUND

In PATENT-1, riociguat significantly improved 6-minute walking distance (6MWD) and a range of secondary end-points in patients with pulmonary arterial hypertension (PAH). We investigated whether riociguat increased the proportion of patients achieving clinically relevant responder thresholds compared with placebo during PATENT-1.

METHODS

In PATENT-1, a randomized, double-blind study, treatment-naïve patients or patients on background PAH-targeted therapy with symptomatic PAH received 12 weeks of treatment with placebo, riociguat up to 2.5 mg 3 times daily, or riociguat up to 1.5 mg 3 times daily. Increases in 6MWD ≥40 m, 6MWD ≥380 m, cardiac index ≥2.5 liter/min/m(2), mixed venous oxygen saturation ≥65%, World Health Organization functional class I/II, N-terminal pro-brain natriuretic peptide <1,800 pg/ml, and right atrial pressure <8 mm Hg were chosen as threshold criteria of a positive response.

RESULTS

Riociguat increased the proportion of treatment-naïve patients and patients on background PAH-targeted therapy with 6MWD ≥380 m at Week 12 (+21% and +15%, respectively), whereas there was a small reduction in 6MWD in placebo-treated patients for both sub-groups. Riociguat also increased the proportion of treatment-naïve patients and patients on background PAH-targeted therapy achieving World Health Organization functional class I/II (+12% and +19%, respectively) and cardiac index ≥2.5 liter/min/m(2) (+30% and +33%, respectively) at Week 12, whereas there was little change in the respective placebo groups.

CONCLUSIONS

Compared with placebo, riociguat increased the proportion of treatment-naïve patients and patients on background PAH-targeted therapy who fulfilled criteria defining a positive response to therapy.

Physicians' and patients' expectations of therapies for pulmonary arterial hypertension: where do they meet?

In recent years, many new, effective therapies for pulmonary arterial hypertension (PAH) have become available and are widely used, yet the long-term prognosis for patients with PAH remains poor. In the absence of a cure, physicians' expectations of PAH-specific therapies are to: 1) improve patients' symptoms and functional capacity; 2) slow disease progression; and 3) improve survival. However, patients with PAH may prioritise other more tangible needs, such as improvements in their ability to carry out their daily tasks and increase their quality of life. Patients with PAH have also called out for social and emotional support from their physicians, caregivers, families and patient associations. Therefore, it is necessary that clinical trials of PAH-specific treatments include end-points that are meaningful to both patients and physicians, and that a multidisciplinary approach to the management of patients with PAH takes into consideration the broader aspects of patients' and caregivers' needs and wishes beyond simple physiological measurements.

An official systematic review of the European Respiratory Society/American Thoracic Society: measurement properties of field walking tests in chronic respiratory disease

This systematic review examined the measurement properties of the 6-min walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT) in adults with chronic respiratory disease.

Studies that report the evaluation or use of the 6MWT, ISWT or ESWT were included. We searched electronic databases for studies published between January 2000 and September 2013.

The 6-min walking distance (6MWD) is a reliable measure (intra-class correlation coefficients ranged from 0.82 to 0.99 in seven studies). There is a learning effect, with greater distance walked on the second test (pooled mean improvement of 26 m in 13 studies). Reliability was similar for ISWT and ESWT, with a learning effect also evident for ISWT (pooled mean improvement of 20 m in six studies). The 6MWD correlates more strongly with peak work capacity (r=0.59–0.93) and physical activity (r=0.40–0.85) than with respiratory function (r=0.10–0.59). Methodological factors affecting 6MWD include track length, encouragement, supplemental oxygen and walking aids. Supplemental oxygen also affects ISWT and ESWT performance. Responsiveness was moderate to high for all tests, with greater responsiveness to interventions that included exercise training.

The findings of this review demonstrate that the 6MWT, ISWT and ESWT are robust tests of functional exercise capacity in adults with chronic respiratory disease.

Outcome of pulmonary endarterectomy in symptomatic chronic thromboembolic disease

Chronic thromboembolic disease is characterised by persistent pulmonary thromboembolic occlusions without pulmonary hypertension. Early surgical treatment with pulmonary endarterectomy may improve symptoms and prevent disease progression. We sought to assess the outcome of pulmonary endarterectomy in symptomatic patients with chronic thromboembolic disease.

Patients with symptomatic chronic thromboembolic disease and a mean pulmonary artery pressure <25 mmHg at baseline with right heart catheterisation and treated with pulmonary endarterectomy between January 2000 and July 2013 were identified. Patients were reassessed at 6 months and at 1 year following surgery.

A total of 42 patients underwent surgery and the median length of stay in hospital was 11 days. There was no in-hospital mortality but complications occurred in 40% of patients. At 1 year, following surgery, 95% of the patients remained alive. There was a significant symptomatic improvement with 95% of patients in the New York Heart Association functional classes I or II at 6 months. There was a significant improvement in quality of life assessed by the Cambridge pulmonary hypertension outcome review questionnaire.

In this carefully selected cohort of chronic thromboembolic disease patients, pulmonary endarterectomy resulted in significant improvement in symptoms and quality of life. Appropriate patient selection is paramount given the known surgical morbidity and mortality, and surgery should only be performed in expert centres.

Home-based pulmonary rehabilitation in patients with inoperable or residual chronic thromboembolic pulmonary hypertension: a preliminary study

BACKGROUND

Management of chronic thromboembolic pulmonary hypertension (CTEPH) has recently improved because of advances in pulmonary endarterectomy (PEA), balloon pulmonary angioplasty (BPA), and disease-targeted medications. However, patients with inoperable CTEPH or persistent pulmonary hypertension (PH) after these interventions continue to exhibit impaired exercise capacity and limited quality of life (QOL).

METHODS

Eight patients with inoperable or residual CTEPH (mean age, 64±12 years; WHO functional class II/III, 6/2; mean pulmonary artery pressure, 47±13 mmHg) in stable condition and receiving disease-targeted medications participated in a 12-week home-based pulmonary rehabilitation program (muscle strength training, respiratory exercises, and walking) with supervised hospital sessions from March 2012 to January 2014. Efficacy parameters were prospectively evaluated at baseline and at completion of the 12-week program.

RESULTS

After completion of the pulmonary rehabilitation program, the 6-minute walking distance (6MWD) (33.3±25.1 m), St. George׳s Respiratory Questionnaire activity score, quadriceps force, and 7-day physical activity level were significantly improved compared with baseline. All subjects completed the rehabilitation program. Although one patient experienced presyncope during the in-hospital exercise sessions, no other severe adverse events or complications of pulmonary rehabilitation were observed.

CONCLUSIONS

These findings suggest that home-based pulmonary rehabilitation with closely supervised sessions may safely improve exercise capacity, leg muscle strength, general activity in daily life and health-related QOL in CTEPH patients.

Pulmonary arterial hypertension: the clinical syndrome

Pulmonary arterial hypertension is a progressive disorder in which endothelial dysfunction and vascular remodeling obstruct small pulmonary arteries, resulting in increased pulmonary vascular resistance and pulmonary pressures. This leads to reduced cardiac output, right heart failure, and ultimately death. In this review, we attempt to answer some important questions commonly asked by patients diagnosed with pulmonary arterial hypertension pertaining to the disease, and aim to provide an explanation in terms of classification, diagnosis, pathophysiology, genetic causes, demographics, and prognostic factors. Furthermore, important molecular pathways that are central to the pathogenesis of pulmonary arterial hypertension are reviewed, including nitric oxide, prostacyclin, endothelin-1, reactive oxygen species, and endothelial and smooth muscle proliferation.

Identification of treatment goals in paediatric pulmonary arterial hypertension

To be able to design goal-oriented treatment strategies in paediatric pulmonary arterial hypertension (PAH), we aimed to identify treatment goals by investigating the prognostic value of treatment-induced changes in noninvasive predictors of transplant-free survival.

66 consecutive, treatment-naïve paediatric PAH patients in the Dutch National Network for Paediatric Pulmonary Hypertension who started taking PAH-targeted drugs between January 2000 and April 2013 underwent prospective, standardised follow-up. Clinical, biochemical and echocardiographic measures were longitudinally collected at treatment initiation and follow-up, and their respective predictive values for transplant-free survival were assessed. Furthermore, the predictive values of treatment-induced changes were assessed.

From the identified set of baseline predictors, the variables World Health Organization functional class (WHO-FC), N-terminal pro-brain natriuretic peptide (NT-proBNP) and tricuspid annular plane systolic excursion (TAPSE) were identified as follow-up predictors in which treatment-induced changes were associated with survival. Patients in whom these variables improved after treatment showed better survival (p<0.002).

Therefore, WHO-FC, NT-proBNP and TAPSE are not only predictors of transplant-free survival in paediatric PAH but can also be used as treatment goals, as treatment-induced improvements in these variables are associated with improved survival. The identification of these variables allows for the introduction of goal-oriented treatment strategies in paediatric PAH.

Minimal important difference in field walking tests in non-cystic fibrosis bronchiectasis following exercise training

BACKGROUND

The 6-min walk distance (6MWD) and incremental shuttle walk distance (ISWD) are clinically meaningful measures of exercise capacity in people with non-cystic fibrosis (CF) bronchiectasis, but the change in walking distance which constitutes clinical benefit is undefined. This study aimed to determine the minimal important difference for the 6MWD and ISWD in non-CF bronchiectasis.

METHODS

Thirty-seven participants with mean FEV1 70% predicted completed both field walking tests before and after an 8-week exercise program. The minimal important difference was calculated using a distribution-based and anchor-based method, with the global rating of change scale used.

RESULTS

The mean change in 6MWD in participants who reported themselves to be unchanged was 10 m, compared to 36 m (small change) and 45 m (substantial change) (p = 0.01). For the ISWD, the mean change in participants who reported themselves to be unchanged was 33 m, compared to 54 m (small change) and 73 m (substantial change) (p = 0.04). The anchor-based method defined the minimal important difference for 6MWD as 24.5 m (AUC 0.76, 95% CI 0.61-0.91) and for ISWD as 35 m (AUC 0.88, 95% CI 0.73-0.99), based on participant's global rating of change. The distribution-based method indicated a value of 22.3 m for the 6MWD and 37 m for the ISWD. There was excellent agreement between the two methods for the 6MWD (kappa = 0.91) and the ISWD (kappa = 0.92).

CONCLUSIONS

Small changes in 6MWD and ISWD may represent clinically important benefits in people with non-CF bronchiectasis. These data are likely to assist in the interpretation of change in exercise capacity following intervention.

Comparative effectiveness and safety of drug therapy for pulmonary arterial hypertension: a systematic review and meta-analysis

BACKGROUND

Current treatments for pulmonary arterial hypertension (PAH) have been shown to improve dyspnea, 6-min walk distance (6MWD), and pulmonary hemodynamics, but few studies were designed to compare treatment regimens or assess the impact of treatment on mortality.

METHODS

We conducted a systematic review to evaluate the comparative effectiveness and safety of monotherapy or combination therapy for PAH using endothelin receptor antagonists, phosphodiesterase inhibitors, or prostanoids. We searched English-language publications of comparative studies that reported intermediate or long-term outcomes associated with drug therapy for PAH. Two investigators abstracted data and rated study quality and applicability.

RESULTS

We identified 28 randomized controlled trials involving 3,613 patients. We found no studies that randomized treatment-naive patients to monotherapy vs combination therapy. There was insufficient statistical power to detect a mortality difference associated with treatment. All drug classes demonstrated increases in 6MWD when compared with placebo, and combination therapy showed improved 6MWD compared with monotherapy. For hospitalization, the OR was lower in patients taking endothelin receptor antagonists or phosphodiesterase-5 inhibitors compared with placebo (OR, 0.34 and 0.48, respectively).

CONCLUSIONS

Although no studies were powered to detect a mortality reduction, monotherapy was associated with improved 6MWD and reduced hospitalization rates. Our findings also suggest an improvement in 6MWD when a second drug is added to monotherapy.

A retrospective study on the effects of pulmonary rehabilitation in patients with pulmonary hypertension

A retrospective analysis of 23 patients was undertaken to evaluate the outcome of pulmonary rehabilitation (PR) in patients with pulmonary hypertension (PH) over a preceding 6-year time frame. Chart review and data analyses were undertaken evaluating pulmonary arterial hypertension pharmacotherapy versus the same therapy with the addition of PR. Analysis included 23 patients who had a mean pulmonary artery pressure of 36.6 while on therapy and who had initial six-minute walk tests (6MWTs) ranging between 54 and 396 meters. Outcomes included 6MWTs and Saint George’s Respiratory Questionnaire. There was no improvement in 6MWT postpharmacotherapy. Patients with low 6MWT <250 meters had substantial gains in 6MWT postrehabilitation (average of 86 meters). As well, those with initial 6MWT >250 meters had a significant improvement of 52.55 meters, documenting the utility of PR in patients with PH. PH patients are increasingly seen in PR clinics as they share many characteristics present in chronic respiratory disease states. There is increasing literature supporting the utility of PR in this population. We have found that patients with 6MWTs as low as <250 meters are also candidates for PR and can demonstrate substantial benefits as measured using the 6MWTs.

Endpoints in PAH clinical trials in the era of combination therapy: how do we decide whether something is working without going bankrupt?

There has been substantial progress in the treatment of pulmonary arterial hypertension using specific disease-targeted therapies. As the number of agents available grows, and as new treatment strategies emerge, it is essential that the endpoints we use to assess efficacy are sufficiently meaningful and sensitive enough to detect changes that are often subtle. Although the six-minute walk has been the traditional primary endpoint in clinical trials, there is now a move towards more patient-centred composite endpoints such as time to clinical worsening. These endpoints need to be more clearly defined and universally applied so as to make direct comparison between new drugs and new combinations possible.

Hemodynamic ranges during daily activities and exercise testing in patients with pulmonary arterial hypertension

BACKGROUND

In patients with pulmonary arterial hypertension (PAH) the relationship between hemodynamic impairment experienced during daily activity and that during exercise testing is not known.

METHODS AND RESULTS

Ten PAH patients received an implantable hemodynamic monitor that continuously recorded and stored right ventricular systolic (RVSP) and mean pulmonary arterial (MPAP) pressures. Before starting a new PAH treatment (baseline) and after 12 weeks on treatment, a 6-minute walk test (6MWT) and a maximal walk test (MAXWT) were performed. Exercise pressure range was measured as the difference between rest before exercise and maximal pressure during 6MWT or MAXWT. Ambulatory range (AMB) was measured as the difference between the lowest (4th percentile) and highest (96th percentile) values recorded over 24 hours. One week of AMBs were averaged for each patient before each exercise test. Mean age was 54 ±18 years, 9 were female, and all were in World Health Organization functional class III. At baseline, RVSP and MPAP increased, respectively, 136 ± 49% and 164 ± 49% during AMB, 63 ± 26% and 79 ± 30% during MAXWT, and 59 ± 32% and 69 ± 33% during 6MWT. There was no difference in pressure change at 12 weeks.

CONCLUSIONS

Changes in RV and PA pressures during exercise tests were relatively small compared with the range seen during ambulatory conditions.

Six-minute walk distance target in elderly patients with idiopathic pulmonary arterial hypertension - consideration of predicted values

BACKGROUND

The number of elderly patients diagnosed with idiopathic pulmonary arterial hypertension (IPAH) is increasing. A 6-min walk distance (6MWD) > 380 m on therapy is associated with improved survival in IPAH. As exercise capacity is naturally decreasing with age, treatment goals for elderly patients might be different from those established for younger patients.

METHODS

Consecutive adult patients diagnosed with IPAH between 1/2005 and 7/2012 were retrospectively included. We analysed the prognostic value of 6MWD targets (in metres and % predicted) with respect to age at diagnosis.

RESULTS

The mean (± SD) 6MWD in 23 patients aged > 65 years at diagnosis compared with 22 younger patients was significantly lower at baseline (262 ± 69 vs. 356 ± 128 m; p = 0.011) and first follow up (310 ± 75 vs. 377 ± 137 m; p = 0.045), while the corresponding % predicted values were similar (62 ± 16% vs. 63 ± 21%; p = 0.854, and 74 ± 16% vs. 68 ± 21%; p = 0.267). The established treatment target of > 380 m 6MWD was met by only 13% of elderly compared with 46% of younger patients (p = 0.016), while the corresponding 6MWD of 78% predicted was exceeded by similar proportions (48% and 46%, respectively; p = 0.873). Survival of patients walking > 380 m or 78% predicted on first follow up was significantly better compared with patients not exceeding the respective threshold (100% vs. 72% and 95% vs. 67% at the end of follow up, respectively; p < 0.05 each).

CONCLUSION

Expression of the 6MWD target as % predicted equalises age-related differences and has similar prognostic power compared with absolute values in patients with IPAH. As elderly patients are less likely to reach the absolute 6MWD threshold, the use of % predicted could be helpful in their individual assessment and adaption of targeted therapy.

Changes in right heart haemodynamics and echocardiographic function in an advanced phenotype of pulmonary hypertension and right heart dysfunction associated with pulmonary fibrosis

BACKGROUND

Pulmonary hypertension (PH)-targeted therapy in the setting of pulmonary fibrosis (PF) is controversial; the main clinical concern is worsening of systemic hypoxaemia. We sought to determine the effects of gentle initiation and chronic administration of parenteral treprostinil on right heart function in patients with PF associated with an advanced PH phenotype.

METHODS

Open-label, prospective analysis of patients with PF-PH referred for lung transplantation (LT). Advanced PH was defined as mean pulmonary artery pressure (mPAP) ≥35 mm Hg. We compared haemodynamics, Doppler echocardiography (DE), oxygenation, dyspnoea and quality of life indices, and 6 min walk distance (6MWD) before and 12 weeks after parenteral treprostinil.

RESULTS

15 patients were recruited in the study. After therapy, there were significant improvements in right heart haemodynamics (right atrial pressure (9.5 ± 3.4 vs 6.0 ± 3.7); mPAP (47 ± 8 vs 38.9 ± 13.4); CI (2.3 ± 0.5 vs 2.7 ± 0.6); pulmonary vascular resistance (698 ± 278 vs 496 ± 229); transpulmonary gradient (34.7 ± 8.7 vs 28.5 ± 10.3); mvO2 (65 ± 7.2 vs 70.9 ± 7.4); and stroke volume index (29.2 ± 6.7 vs 33 ± 7.3)) and DE parameters reflecting right heart function (right ventricular (RV) end diastolic area (36.4 ± 5.2 vs 30.9 ± 8.2 cm(2)), left ventricular eccentricity index (1.7 ± 0.6 vs 1.3 ± 0.5), tricuspid annular planar systolic excursion (1.6 ± 0.5 vs 1.9 ± 0.2 cm)). These changes occurred without significant alteration in systemic oxygenation, heart rate, or mean systemic arterial pressure. In addition, improvements were seen in 6MWD (171 ± 93 vs 230 ± 114), 36-Item Short Form Health Survey Mental Component Summary aggregate (38 ± 11 vs 44.2 ± 10.7), University of California, San Diego Shortness of Breath Questionnaire (87 ± 17.1 vs 73.1 ± 21), and brain natriuretic peptide (558 ± 859 vs 228 ± 340).

CONCLUSIONS

PH-targeted therapy may improve right heart haemodynamics and echocardiographic function without affecting systemic oxygen saturation in an advanced PH phenotype associated with RV dysfunction in the setting of PF.

Treatment goals of pulmonary hypertension

With significant therapeutic advances in the field of pulmonary arterial hypertension, the need to identify clinically relevant treatment goals that correlate with long-term outcome has emerged as 1 of the most critical tasks. Current goals include achieving modified New York Heart Association functional class I or II, 6-min walk distance >380 m, normalization of right ventricular size and function on echocardiograph, a decreasing or normalization of B-type natriuretic peptide (BNP), and hemodynamics with right atrial pressure <8 mm Hg and cardiac index >2.5 mg/kg/min(2). However, to more effectively prognosticate in the current era of complex treatments, it is becoming clear that the "bar" needs to be set higher, with more robust and clearer delineations aimed at parameters that correlate with long-term outcome; namely, exercise capacity and right heart function. Specifically, tests that accurately and noninvasively determine right ventricular function, such as cardiac magnetic resonance imaging and BNP/N-terminal pro-B-type natriuretic peptide, are emerging as promising indicators to serve as baseline predictors and treatment targets. Furthermore, studies focusing on outcomes have shown that no single test can reliably serve as a long-term prognostic marker and that composite treatment goals are more predictive of long-term outcome. It has been proposed that treatment goals be revised to include the following: modified New York Heart Association functional class I or II, 6-min walk distance ≥ 380 to 440 m, cardiopulmonary exercise test-measured peak oxygen consumption >15 ml/min/kg and ventilatory equivalent for carbon dioxide <45 l/min/l/min, BNP level toward "normal," echocardiograph and/or cardiac magnetic resonance imaging demonstrating normal/near-normal right ventricular size and function, and hemodynamics showing normalization of right ventricular function with right atrial pressure <8 mm Hg and cardiac index >2.5 to 3.0 l/min/m(2).

A cross-sectional study of differences in 6-min walk distance in healthy adults residing at high altitude versus sea level

Background

We sought to determine if adult residents living at high altitude have developed sufficient adaptation to a hypoxic environment to match the functional capacity of a similar population at sea level. To test this hypothesis, we compared the 6-min walk test distance (6MWD) in 334 residents living at sea level vs. at high altitude.

Methods

We enrolled 168 healthy adults aged ≥35 years residing at sea level in Lima and 166 individuals residing at 3,825 m above sea level in Puno, Peru. Participants completed a 6-min walk test, answered a sociodemographics and clinical questionnaire, underwent spirometry, and a blood test.

Results

Average age was 54.0 vs. 53.8 years, 48% vs. 43% were male, average height was 155 vs. 158 cm, average blood oxygen saturation was 98% vs. 90%, and average resting heart rate was 67 vs. 72 beats/min in Lima vs. Puno. In multivariable regression, participants in Puno walked 47.6 m less (95% CI -81.7 to -13.6 m; p < 0.01) than those in Lima. Other variables besides age and height that were associated with 6MWD include change in heart rate (4.0 m per beats/min increase above resting heart rate; p < 0.001) and percent body fat (-1.4 m per % increase; p = 0.02).

Conclusions

The 6-min walk test predicted a lowered functional capacity among Andean high altitude vs. sea level natives at their altitude of residence, which could be explained by an incomplete adaptation or a protective mechanism favoring neuro- and cardioprotection over psychomotor activity.

Systemic sclerosis-associated pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is the leading cause of death in systemic sclerosis (SSc) and affects up to 12% of all patients with SSc, with a 50% mortality rate within 3 years of PAH diagnosis. Compared with the idiopathic form of PAH (IPAH), patients with SSc-associated PAH (SSc-PAH) have a threefold increased risk of death and may receive a diagnosis late in the course of disease because of insidious onset and the high prevalence of cardiac, musculoskeletal, and pulmonary parenchymal comorbidities. Treatment with conventional forms of PAH therapy often yield poor results compared with IPAH cohorts; unfortunately, the exact reasons behind this remain poorly understood but likely include variations in the pathologic mechanisms, differences in cardiovascular response to increasing afterload, and inadequate strategies to detect and treat SSc-PAH early in its course. Current methods for screening and longitudinal evaluation of SSc-PAH, such as the 6-min walk test, transthoracic echocardiography, and MRI, each have notable advantages and disadvantages. We provide an up-to-date, focused review of SSc-PAH and how it differs from IPAH, including pathogenesis, appropriate screening for disease onset, and new approaches to treatment and longitudinal assessment of this disease.

Rationale and methodology for a multicentre randomised trial of fibrinolysis for pulmonary embolism that includes quality of life outcomes

BACKGROUND

Submassive pulmonary embolism (PE) has a low mortality rate but can degrade functional capacity.

OBJECTIVE

The present study aims to provide rationale, methodology, and initial findings of a multicentre, randomised trial of fibrinolysis for PE that used a composite end-point, including quality of life measures.

METHODS

This investigator-initiated study was funded by a contract between a corporate partner and the investigator's hospital (the prime site). The investigator was the Food and Drug Administration (FDA) sponsor. The prime site subcontracted, indemnified, and trained consortia members. Consenting, normotensive patients with PE and right ventricular strain (by echocardiography or biomarkers) received low-molecular-weight heparin and random assignment to a single bolus of tenecteplase or placebo in double-blinded fashion. The outcomes were: (i) in-hospital rate of intubation, vasopressor support, and major haemorrhage, or (ii) at 90 days, death, recurrent PE, or composite that defined poor quality of life (echocardiography, 6 min walk test and surveys). The planned sample size was n = 200.

RESULTS

Eight sites enrolled 87 patients over 5 years. The ratio of patients screened for each enrolled was 7.4 to 1, equating to 11 h screening time per patient enrolled. Primary barrier to enrolment was the cost of screening. Two patients died (2.5%, 95%CI [0-8%]), one developed shock, but 18 (22%, 95%CI: [13-30%]) had a poor quality of life.

CONCLUSIONS

An investigator-initiated, FDA-regulated, multicentre trial of fibrinolysis for submassive PE was conducted, but was limited by screening costs and a low mortality rate. Quality of life measurements might represent a more important patient-centred end-point.

The clinical relevance of outcomes used in late-onset Pompe disease: can we do better?

Pompe disease/glycogen storage disease type II, is a rare, lysosomal storage disorder associated with progressive proximal myopathy, causing a gradual loss of muscular function and respiratory insufficiency. Studies of patients with late-onset Pompe disease have used endpoints such as the 6-minute walking test (6MWT) and forced vital capacity (FVC) to assess muscular and respiratory function during disease progression or treatment. However, the relevance of these markers to late-onset Pompe disease and the minimal clinically important difference (MCID) for these endpoints in late-onset Pompe disease have not yet been established. A literature search was carried out to identify studies reporting the MCID (absolute and relative) for the 6MWT and FVC in other diseases. The MCIDs determined in studies of chronic respiratory diseases were used to analyze the results of clinical studies of enzyme replacement therapy in late-onset Pompe disease. In 9 of the 10 late-onset Pompe disease studies reviewed, changes from baseline in the 6MWT were above or within the MCID established in respiratory diseases. Clinical improvement was perceived by patients in 6 of the 10 studies. In 6 of the 9 late-onset Pompe disease studies that reported FVC, the changes from baseline in percentage predicted FVC were above or within the MCID established in respiratory diseases and the difference was perceived as either an improvement or stabilization by patients. However, applying the 6MWT and FVC MCIDs from studies of chronic respiratory diseases to late-onset Pompe disease has several important limitations. Outcome measures in muscular dystrophies include composite measures of muscle function and gait, as well as Rasch-designed and validated tools to assess disease-related quality of life and activities of daily living. Given that the relevance to patients with late-onset Pompe disease of the 6MWT or FVC MCIDs established for chronic respiratory diseases is unclear, these measures should be evaluated specifically in late-onset Pompe disease and alternative outcome measures more specific to neuromuscular disease considered.