The 6-min walk test (6MW) as an efficacy endpoint in pulmonary arterial hypertension clinical trials: Demonstration of a ceiling effect

Cardiac effort and 6-min walk distance correlate with stroke volume measured by cardiac magnetic resonance imaging

Right ventricular (RV) dysfunction in pulmonary arterial hypertension (PAH) is associated with poor outcomes. Cardiac magnetic resonance imaging (cMRI) is the gold standard for volumetric assessment, and few reports have correlated 6-min walk distance (6MWD) and cMRI parameters in PAH. Cardiac Effort, (the number of heart beats used during 6-min walk test)/(6MWD), incorporates physiologic changes into walk distance and has been associated with stroke volume (SV) measured by nuclear imaging and indirect Fick. Here, we aimed to interrogate the relationship of Cardiac Effort and 6MWD with SV measured by the gold standard, cMRI. This was a single-center, observational, prospective study in Group 1 PAH patients. Subjects completed 6-min walk with heart rate monitoring (Cardiac Effort) and cMRI within 24 h. cMRI was correlated to Cardiac Effort and 6MWD using Spearman Correlation Coefficient. Twenty-five participants with a wide range of RV function completed both cMRI and Cardiac Effort. There was a strong correlation between left ventricle SV index and both Cardiac Effort (r = -0.70, p = 0.0001) and 6MWD (r = 0.67, p = 0.0002). Cardiac Effort and 6MWD were statistically separated in patients at prognostically significant thresholds of left ventricle SV index (>31 ml/m2), RV Ejection Fraction (>35%), and SV/End Systolic Volume ( > 0.53). Cardiac Effort and 6MWD are noninvasive ways to gain insight into those with impaired SV. 6MWD may correlate better with SV than previously thought and heart rate monitoring provides physiologic context to the walk distance obtained.

Ralinepag Phase II Open-Label Extension Study in Patients with Pulmonary Arterial Hypertension

INTRODUCTION

Ralinepag is a potent, titratable, orally administered prostacyclin (IP) receptor agonist to treat pulmonary arterial hypertension. A phase II randomized, double-blind, parallel-group, placebo-controlled, 22-week study of immediate-release (IR) ralinepag safety and efficacy met its primary endpoint, significantly reducing pulmonary vascular resistance (PVR) compared with placebo. This phase II open-label extension (OLE) study assessed long-term safety and tolerability of ralinepag.

METHODS

Participants were eligible for the OLE if they completed the parent study or experienced a clinical worsening event while receiving placebo. Those previously receiving IR ralinepag remained on their current dose, and participants formerly administered placebo were titrated to the highest tolerated dose. Participants were transitioned to an extended-release ralinepag formulation toward the end of the OLE. The primary objective evaluated long-term safety and tolerability; secondary endpoints included changes in 6-min walk distance (6MWD), World Health Organization/New York Heart Association functional class, clinical worsening, and hemodynamic measures.

RESULTS

In total, 45/61 participants enrolled in the OLE study, 30 from the IR ralinepag group and 15 from the placebo group. The most common adverse events (AEs) were known prostacyclin-related effects (e.g., headache, 64.4%; diarrhea, 37.8%; jaw pain, 33.3%). There was a notable decline in AEs after reaching and maintaining a stable dose. At month 24 after entering the OLE, 6MWD significantly increased by a mean of 36.3 m (P = 0.004) from OLE baseline, and most participants remained stable in their functional class (84.8%). Post-baseline PVR in 1 or 2 years decreased by a median of 52.2 dyn.s/cm5 and mean pulmonary arterial pressure decreased by a median of 2.0 mmHg (P = 0.05).

CONCLUSION

Ralinepag produced sustained, durable improvements in 6MWD along with durable reductions in PVR and a manageable AE profile. Most participants continuing treatment with ralinepag maintained functional measures throughout the OLE and those switching from placebo to ralinepag often experienced functional improvements.

Triple vasodilator therapy in pulmonary arterial hypertension associated with congenital heart disease

OBJECTIVE

This study assessed the long-term effects of triple therapy with prostanoids on patients with pulmonary arterial hypertension associated with congenital heart disease (PAH-CHD), as there is limited information on the safety and efficacy of this treatment approach.

METHODS

A retrospective cohort study was conducted on patients with PAH-CHD who were actively followed up at our centre. All patients were already receiving dual combination therapy at maximum doses. Clinical characteristics, including functional class (FC), 6-minute walking test distance (6MWTD) and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, were documented before initiating triple therapy and annually for a 2-year follow-up period.

RESULTS

A total of 60 patients were included in the study, with a median age of 41 years and 68% being women. Of these, 32 had Eisenmenger syndrome, 9 had coincidental shunts, 18 had postoperative PAH and 1 had a significant left-to-right shunt. After 1 year of triple combination initiation, a significant improvement in 6MWTD was observed (406 vs 450; p=0.0027), which was maintained at the 2-year follow-up. FC improved in 79% of patients at 1 year and remained stable in 76% at 2 years. NT-proBNP levels decreased significantly by 2 years, with an average reduction of 199 ng/L. Side effects were experienced by 33.3% of patients but were mostly mild and manageable. Subgroup analysis showed greater benefits in patients without Eisenmenger syndrome and those with pre-tricuspid defects.

CONCLUSIONS

Triple therapy with prostanoids is safe and effective for patients with PAH-CHD, improving FC, 6MWTD and NT-proBNP levels over 2 years. The treatment is particularly beneficial for patients with pre-tricuspid defects and non-Eisenmenger PAH-CHD.

Simplified risk stratification based on cardiopulmonary exercise test: A Spanish two-center experience

A simplified 4-strata risk stratification approach based on three variables is widespread in pulmonary arterial hypertension (PAH) at follow-up. This study aimed to assess the impact of replacing the 6-min walk test (6MWT) with the peak 02 uptake evaluated by the cardiopulmonary exercise test (CPET) on risk stratification by this scale. We included 180 prevalent patients with PAH from two reference hospitals in Spain, followed up between 2006 and 2022. Patients were included if all the variables of interest were available within a 3-month period on the Spanish Registry of Pulmonary Arterial Hypertension (REHAP): functional class (FC); NT-proBNP; 6MWT; and CPET. The original 4-strata model (NT-proBNP, 6MWT, FC) identified most patients at low or intermediate-low risk (36.7% and 51.1%, respectively). Notably, the modified scale (NT-proBNP, CPET, FC) improved the identification of patients at intermediate-high risk up to 18.9%, and at high risk up to 1.1% in comparison with the previous 12.2% and 0.0% in the original scale. This new model increased the number of patients correctly classified into higher-risk strata (positive NRI of 0.06), as well as classified more patients without events in lower-risk strata (negative NRI of 0.04). The proposed score showed a slightly superior prognostic capacity compared with the original model (Harrel's C-index 0.717 vs. 0.709). Using O2 uptake instead of distance walked in the 6MWT improves the identification of high-risk patients using the 4-strata scale. This change could have relevant prognostic implications and lead to changes in the specific treatment of PAH.

Change in Right-to-Left Shunt Fraction in Patients with Chronic Thromboembolic Pulmonary Hypertension after Pulmonary Endarterectomy

BACKGROUND

Pulmonary endarterectomy (PEA) is the treatment of choice for patients with chronic thromboembolic pulmonary hypertension (CTEPH) with accessible lesions. Breathing pure oxygen (hyperoxia) during right heart catheterization (RHC) allows for the calculation of the right-to-left shunt fraction (Qs/Qt). In the absence of intracardiac shunt, Qs/Qt can be used as a marker of ventilation-perfusion mismatch in patients with CTEPH. This study involved investigating Qs/Qt after PEA and its relation to other disease-specific outcomes.

STUDY DESIGN AND METHODS

This study is a retrospective study that focuses on patients with operable CTEPH who had Qs/Qt assessment during RHC before and 1 year after PEA. Additionally, 6 min walking distance (6MWD), WHO functional class (WHO-FC), and NT-proBNP were assessed to calculate a four-strata risk score.

RESULTS

Overall, 16 patients (6 females) with a median age of 66 years (quartiles 55; 74) were included. After PEA, an improvement in mean pulmonary artery pressure (38 [32; 41] to 24 [18; 28] mmHg), pulmonary vascular resistance (5.7 [4.0; 6.8] to 2.5 [1.4; 3.8] WU), oxygen saturation (92 [88; 93]% to 94 [93; 95]%), WHO-FC, and risk score was observed (all p < 0.05). No improvement in median Qs/Qt could be detected (13.7 [10.0; 17.5]% to 13.0 [11.2; 15.6]%, p = 0.679). A total of 7 patients with improved Qs/Qt had a significant reduction in risk score compared to those without improved Qs/Qt.

CONCLUSION

PEA did not alter Qs/Qt assessed after 1 year in operable CTEPH despite an improvement in hemodynamics and risk score, potentially indicating a persistent microvasculopathy. In patients whose shunt fraction improved with PEA, the reduced shunt was associated with an improvement in risk score.

Efficacy of a Commercial Physical Activity Monitor in Longitudinal Tracking of Patients With Pulmonary Hypertension: A Pilot Study

BACKGROUND

Patients with pulmonary arterial hypertension have quality-of-life limitations, decreased exercise capacity, and poor prognosis if the condition is left untreated. Standard exercise testing is routinely performed to evaluate patients with pulmonary arterial hypertension but may be limited in its ability to monitor activity levels in daily living.

OBJECTIVE

To evaluate the validity of the commercial Fitbit Charge HR as a tool to assess real-time exercise capacity as compared with standard exercise testing.

METHODS

Ambulatory pediatric and adult patients were enrolled and given a Fitbit with instructions to continuously wear the device during waking hours. Patients underwent a 6-minute walk test, cardiopulmonary exercise test, and a 36-Item Short Form Health Survey on the day of enrollment and follow-up. Twenty-seven ambulatory patients with pulmonary arterial hypertension were enrolled, and 21 had sufficient data for analyses (median age, 25 years [range, 13-59 years]; 14 female participants).

RESULTS

Daily steps measured by the Fitbit had a positive correlation with 6-minute walk distance (r = 0.72, P = .03) and an inverse trend with World Health Organization functional class. On the 36-Item Short Form Health Survey, 77% of patients reported improvement in vitality (P = .055). At follow-up, there was a strong correlation between number of steps recorded by Fitbit and role limitations because of physical problems (r = 0.88, P = .02) and weaker correlations with other quality-of-life markers.

CONCLUSION

The findings of this pilot study suggest activity monitors may have potential as a simple and novel method of assessing longitudinal exercise capacity and activity levels in patients with pulmonary hypertension. Further study in larger cohorts of patients is warranted to determine which accelerometer measures correlate best with outcomes.

Associations between symptoms and functional capacity in patients after COVID-19 infection and community controls

BACKGROUND

Post-acute sequelae of COVID-19 (PASC or 'long COVID') reflect ongoing symptoms, but these are non-specific and common in the wider community. Few reports of PASC have been compared with a control group.

AIMS

To compare symptoms and objective impairment of functional capacity in patients with previous COVID-19 infection with uninfected community controls.

METHODS

In this community-based, cross-sectional study of functional capacity, 562 patients from Western Melbourne who had recovered from COVID-19 infections in 2021 and 2022 were compared with controls from the same community and tested for functional capacity pre-COVID-19. Functional impairment (<85% of the predicted response) was assessed using the Duke Activity Status Index (DASI) and 6-min walk distance (6MWD) test. A subgroup underwent cardiopulmonary exercise testing before and after exercise training.

RESULTS

Of 562 respondents (age 54 ± 12 years, 69% women), 389 were symptomatic. Functional impairment (<85% predicted metabolic equivalent of tasks) was documented by DASI in 149 participants (27%), and abnormal 6MWD (<85% predicted) was observed in 14% of the symptomatic participants. Despite fewer risk factors and younger age, patients with COVID-19 had lower functional capacity by 6MWD (P < 0.001) and more depression (P < 0.001) than controls. In a pilot group of seven participants (age 58 ± 12 years, two women, VO2 18.9 ± 5.7 mL/kg/min), repeat testing after exercise training showed a 20% increase in peak workload.

CONCLUSIONS

Although most participants (69%) had symptoms consistent with long COVID, significant subjective functional impairment was documented in 27% and objective functional impairment in 14%. An exercise training programme might be beneficial for appropriately selected patients.

Peak steps: Capacity for activity improves after adding approved therapy in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) patients have low activity. Activity intensity or duration could be a measure of clinical status or improvement. We aimed to determine whether standard or novel actigraphy measures could detect increases in activity after adding therapy. This was a prospective, single-center observational study evaluating activity after adding therapy in Group 1 PAH; we also report a validation cohort. For our study, two different accelerometers were used, a wrist (ActiGraph) and chest (MC10) device. Patients were analyzed in two groups, Treatment Intensification (TI, adding therapy) or Stable. Both groups had baseline monitoring periods of 7 days; the TI group had follow-up at 3 months, while Stables had follow-up within 4 weeks to assess stability. Activity time and steps were reported from both devices' proprietary algorithms. In ActiGraph only, steps in 1-min intervals throughout the day were ranked (not necessarily contiguous). Average values for each week were calculated and compared using nonparametric testing. Thirty patients had paired data (11 Stable and 19 TI). There was no between-group difference at baseline; we did not observe therapy-associated changes on average daily steps or activity time/intensity. The top 5 min of steps (capacity) increased after adding therapy; there was no difference in the stable group. This key finding was validated in a previously reported randomized trial studying a behavioral intervention to increase exercise. Total daily activity metrics are influenced by both disease and non-disease factors, making therapy-associated change difficult to detect. Peak minute steps were a treatment-responsive marker in both a pharmacologic and training intervention.

Heterogeneity of treatment effects by risk in pulmonary arterial hypertension

BACKGROUND

It is currently unknown if disease severity modifies response to therapy in pulmonary arterial hypertension (PAH). We aimed to explore if disease severity, as defined by established risk-prediction algorithms, modified response to therapy in randomised clinical trials in PAH.

METHODS

We performed a meta-analysis using individual participant data from 18 randomised clinical trials of therapy for PAH submitted to the United States Food and Drug Administration to determine if predicted risk of 1-year mortality at randomisation modified the treatment effect on three outcomes: change in 6-min walk distance (6MWD), clinical worsening at 12 weeks and time to clinical worsening.

RESULTS

Of 6561 patients with a baseline US Registry to Evaluate Early and Long-Term PAH Disease Management (REVEAL 2.0) score, we found that individuals with higher baseline risk had higher probabilities of clinical worsening but no difference in change in 6MWD. We detected a significant interaction of REVEAL 2.0 risk and treatment assignment on change in 6MWD. For every 3-point increase in REVEAL 2.0 score, there was a 12.49 m (95% CI 5.86-19.12 m; p=0.001) greater treatment effect in change in 6MWD. We did not detect a significant risk by treatment interaction on clinical worsening with most of the risk-prediction algorithms.

CONCLUSIONS

We found that predicted risk of 1-year mortality in PAH modified treatment effect as measured by 6MWD, but not clinical worsening. Our findings highlight the importance of identifying sources of treatment heterogeneity by predicted risk to tailor studies to patients most likely to have the greatest treatment response.

Time to clinical improvement: an appropriate surrogate endpoint for pulmonary arterial hypertension medication trials

Background

Many retrospective studies suggest that risk improvement may be a suitable efficacy surrogate endpoint for pulmonary arterial hypertension (PAH) medication trials. This prospective multicenter study assessed the efficacy of domestic ambrisentan in Chinese PAH patients and observed risk improvement and time to clinical improvement (TTCI) under ambrisentan treatment.

Methods

Eligible patients with PAH were enrolled for a 24-week treatment with ambrisentan. The primary efficacy endpoint was 6-min walk distance (Δ6MWD). The exploratory endpoints were risk improvement and TTCI, defined as the time from initiation of treatment to the first occurrence of risk improvement.

Results

A total of 83 subjects were enrolled. After ambrisentan treatment, Δ6MWD was significantly increased at week 12 (42.2 m, P < 0.0001) and week 24 (53.4 m, P < 0.0001). Within 24 weeks, risk improvement was observed in 53 (64.6%) subjects (P < 0.0001), which is higher than WHO-FC (30.5%) and TAPSE/PASP (32.9%). Kaplan-Meier analysis of TTCI showed a median improvement time of 131 days and a cumulative improvement rate of 75.1%. Also, TTCI is consistent across different baseline risk status populations (log-rank P = 0.51). The naive group had more risk improvement (P = 0.043) and shorter TTCI (log-rank P = 0.008) than the add-on group, while Δ6MWD did not show significant differences between the two groups.

Conclusions

Domestic ambrisentan significantly improved the exercise capacity and risk status of Chinese PAH patients. TTCI has a relatively high positive event rate within 24-week treatment duration. Compared to Δ6MWD, TTCI is not affected by baseline risk status. Additionally, TTCI could identify better improvements in patients, which Δ6MWD does not detect. TTCI is an appropriate composite surrogate endpoint for PAH medication trials.

Clinical Trial Registration

NCT No. [ClinicalTrials.gov], identifier [NCT05437224].

Minimal Clinically Important Difference of the 6-Minute Walk Distance in Patients Undergoing Lumbar Spinal Canal Stenosis Surgery: 12 Months Follow-Up

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

We evaluated the responsiveness of the 6-minute walk distance (6MWD) and determined the threshold of the minimal clinically important difference (MCID) in patients who underwent lumbar spinal stenosis (LSS) surgery.

SUMMARY OF BACKGROUND DATA

Little evidence exists on the MCID of 6MWD after LSS surgery. The 6MWD is an objective gait assessment that can be measured quickly.

MATERIALS AND METHODS

In total, 126 patients (74 men; average age, 72.2 ± 6.5 yr) were included and assessed preoperatively and at 12 months postoperatively. We used the Oswestry Disability Index (ODI), as an anchor to calculate the MCID for the 6MWD and measured internal and external responsiveness of the 6MWD. The external responsiveness was assessed in 2 ways: (1) One based on the anchoring questionnaire and (2) another based on the scale distribution. The anchor-based approach was evaluated using the Spearman rank correlation coefficient and receiver-operating characteristic curve. The distribution-based approach was evaluated using the minimal detectable change.

RESULTS

The ODI scores and 6MWD for each anchor significantly improved postoperatively. The change in the 6MWD was significantly correlated with change in the ODI (6 mo, r = -0.45; 12 mo, r = -0.49). The receiver-operating characteristic analysis demonstrated good discriminative properties for the 6MWD using the ODI anchor (6 mo, 0.72; 12 mo, 0.78). The cutoff values for 6MWD were 102.3 and 57.5 at 6 and 12 months, respectively. In the distribution-based approach, the minimal detectable change for the 6MWD was 95.7 m.

CONCLUSIONS

We validated both the internal and external responsiveness of the 6MWD using the ODI and estimated the MCID in the 6MWD for patients undergoing LSS surgery. However, there was lower validity for the MCID among those participants with the high walking ability and low disability at baseline.

Efficacy and safety of non-prostanoid prostacyclin receptor agonist for pulmonary hypertension: A meta-analysis

BACKGROUND

Oral non-prostanoid prostacyclin receptor agonists therapies have been recommended for pulmonary arterial hypertension in many countries.

OBJECTIVE

We aimed to evaluate the specific impact of non-prostanoid prostacyclin receptor agonists on pulmonary hypertension and to explore the influence of study characteristics on results.

METHODS

PubMed, Embase, and ClinicalTrials.gov were systematically searched from inception to July 12, 2022. Randomized controlled trials comparing non-prostanoid prostacyclin receptor agonists administration with placebo for treating pulmonary hypertension were included. Two researchers independently selected eligible studies, assessed the bias risk and extracted related data. RevMan5.1 was used for performing the statistical analysis and the assessment of bias risk of the enrolled studies. PROSPERO registered number CRD42022304172.

RESULTS

Seven trials involving 1727 patients were included. Pooled analyses indicated non-prostanoid prostacyclin receptor agonists significantly reduced clinical worsening events (risk ratio [RR], 0.63; 95% confidence interval [CI], 0.54 to 0.74), increased 6-min walk distance (mean difference [MD], 10 m; 95% CI, 3-17 m), decreased pulmonary vascular resistance (MD, -121 dyn s/cm⁵; 95% CI, -172 to -69 dyn s/cm⁵) and increased cardiac index (MD, 0.38 L/min/m²; 95% CI, 0.26-0.50 L/min/m²) compared with the control. No significant differences in all-cause mortality (RR, 0.86; 95% CI, 0.26 to 2.78), NYHA/WHO functional class (RR, 1.16; 95% CI, 0.61 to 2.18), mean pulmonary artery pressure (MD, -0.88 mmHg; 95% CI, -2.20 to 0.44 mmHg), right atrial pressure (MD, 0.66 mmHg; 95% CI, -0.59 to 1.90 mmHg) and total adverse events (RR, 1.05; 95% CI, 0.99 to 1.10) were found between non-prostanoid prostacyclin receptor agonists group and control group.

CONCLUSION

Non-prostanoid prostacyclin receptor agonists treatment exerted benefits on clinical worsening, pulmonary vascular resistance, and cardiac index in pulmonary hypertension patients, without increasing the incidence of total adverse events.

Effect of 5 weeks of oral acetazolamide on patients with pulmonary vascular disease: A randomized, double-blind, cross-over trial

BACKGROUND

The carbonic anhydrase inhibitor acetazolamide stimulates ventilation through metabolic acidosis mediated by renal bicarbonate excretion. In animal models, acetazolamide attenuates acute hypoxia-induced pulmonary hypertension (PH), but its efficacy in treating patients with PH due to pulmonary vascular disease (PVD) is unknown.

METHODS

28 PVD patients (15 pulmonary arterial hypertension, 13 distal chronic thromboembolic PH), 13 women, mean±SD age 61.6±15.0 years stable on PVD medications, were randomised in a double-blind crossover protocol to 5 weeks acetazolamide (250mg b.i.d) or placebo separated by a ≥2 week washout period. Primary endpoint was the change in 6-minute walk distance (6MWD) at 5 weeks. Additional endpoints included safety, tolerability, WHO functional class, quality of life, arterial blood gases, and hemodynamics (by echocardiography).

RESULTS

Acetazolamide had no effect on 6MWD compared to placebo (treatment effect: mean change [95%CI] -18 [-40 to 4]m, p=0.102) but increased arterial blood oxygenation through hyperventilation induced by metabolic acidosis. Other measures including pulmonary hemodynamics were unchanged. No severe adverse effects occurred, side effects that occurred significantly more frequently with acetazolamide vs. placebo were change in taste (22/0%), paraesthesia (37/4%) and mild dyspnea (26/4%).

CONCLUSIONS

In patients with PVD, acetazolamide did not change 6MWD compared to placebo despite improved blood oxygenation. Some patients reported a tolerable increase in dyspnoea during acetazolamide treatment, related to hyperventilation, induced by the mild drug-induced metabolic acidosis. Our findings do not support the use of acetazolamide to improve exercise in patients with PVD at this dosing.

CLINICALTRIALS

GOV IDENTIFIER

NCT02755298.

Cardiac Effort to Compare Clinic and Remote 6-Minute Walk Testing in Pulmonary Arterial Hypertension

BACKGROUND

The SARS-CoV-2 pandemic has limited objective physiologic assessments. A standardized remote alternative is not currently available. "Cardiac effort" (CE), that is, the total number of heart beats divided by the 6-min walk test (6MWT) distance (beats/m), has improved reproducibility in the 6MWT and correlated with right ventricular function in pulmonary arterial hypertension.

RESEARCH QUESTION

Can a chest-based accelerometer estimate 6MWT distance remotely? Is remote cardiac effort more reproducible than 6MWT distance when compared with clinic assessment?

STUDY DESIGN AND METHODS

This was a single-center, prospective observational study, with institutional review board approval, completed between October 2020 and April 2021. Group 1 subjects with pulmonary arterial hypertension, receiving stable therapy for > 90 days, completed four to six total 6MWTs during a 2-week period to assess reproducibility. The first and last 6MWTs were performed in the clinic; two to four remote 6MWTs were completed at each participant's discretion. Masks were not worn. BioStamp nPoint sensors (MC10) were worn on the chest to measure heart rate and accelerometry. Two blinded readers counted laps, using accelerometry data obtained on the clinic or user-defined course. Averages of clinic variables and remote variables were used for Wilcoxon matched-pairs signed rank tests, Bland-Altman plots, or Spearman correlation coefficients.

RESULTS

Estimated 6MWT distance, using the MC10, correlated strongly with directly measured 6MWT distance (r = 0.99; P < .0001; in 20 subjects). Remote 6MWT distances were shorter than clinic 6MWT distances: 405 m (330-464 m) vs 389 m (312-430 m) (P = .002). There was no difference between in-clinic and remote CE: 1.75 beats/m (1.48-2.20 beats/m) vs 1.86 beats/m (1.57-2.14 beats/m) (P = .14).

INTERPRETATION

Remote 6MWT was feasible on a user-defined course; 6MWT distance was shorter than clinic distance. CE calculated by chest heart rate and accelerometer-estimated distance provides a reproducible remote assessment of exercise tolerance, comparable to the clinic-measured value.

Telehealth: A winning weapon to face the COVID-19 outbreak for patients with pulmonary arterial hypertension

Background

COVID-19 pandemic severely affected national health systems, altering the modality and the type of care of patients with acute and chronic diseases. To minimize the risk of exposure to SARS-CoV2 for patients and health professionals, face-to-face visits were cancelled or postponed and the use of telemedicine was strongly encouraged. This reorganization involved especially patients with rare diseases needing periodic comprehensive assessment, such as pulmonary arterial hypertension (PAH).

Main body

The paper reports a proposal of strategy adopted for patients followed at our PAH center in Rome, where patients management was diversified based on clinical risk according to the European Society of Cardiology/European Respiratory Society PH guidelines-derived score and the REVEAL 2.0 score. A close monitoring and support of these patients were made possible by policy changes reducing barriers to telehealth access and promoting the use of telemedicine. Synchronous/asynchronous modalities and remote monitoring were used to collect and transfer medical data in order to guide physicians in therapeutic-decision making. Conversely, the use of implantable monitors providing hemodynamic information and echocardiography-mobile devices wirelessly connecting was limited by the poor experience existing in this setting. Large surveys and clinical trials are welcome to test the potential benefit of the optimal balance between traditional PAH management and telemedicine opportunities.

Conclusion

Italy was found unprepared to manage the dramatic effects caused by COVID-19 on healthcare systems. In this emergency situation telemedicine represented a promising tool especially in rare diseases as PAH, but was limited by its scattered availability and legal and ethical issues. Cohesive partnership of health care providers with regional public health officials is needed to prioritize PAH patients for telemedicine by dedicated tools.

Prediction of peak oxygen uptake from 6-minute walk test in pulmonary hypertension

Maximal oxygen uptake (V′_O2max), assessed by cardiopulmonary exercise testing (CPET), is an important parameter for risk assessment in patients with pulmonary hypertension (PH). However, CPET may not be available for all PH patients. Thus, we aimed to test previously published predictive models of V′_O2max from the 6-min walk distance (6MWD) for their accuracy and to create a new model.

We tested four models (two by Ross et al. (2010), one by Miyamoto et al. (2000) and one by Zapico et al. (2019)). To derive a new model, data were split into a training and testing dataset (70:30) and step-wise linear regression was performed. To compare the different models, the standard error of the estimate (SEE) was calculated and the models graphically compared by Bland–Altman plots. Sensitivity and specificity for correct prediction into low-risk classification (V′_O2max >15 mL/min/kg) was calculated for all models.

A total of 276 observations were included in the analysis (194/82 training/testing dataset); 6MWD and V′_O2max were significantly correlated (r=0.65, p<0.001). Linear regression showed significant correlation of 6MWD, weight and heart rate response (HRR) with V′_O2max and the best fitting prediction equation was: V′_O2max = 1.83 + 0.031 × 6MWD (m) – 0.023 × weight (kg) – 0.015 × HRR (bpm). SEEs for the different models were 3.03, 3.22, 4.36 and 3.08 mL/min/kg for the Ross et al., Miyamoto et al., Zapico et al. models and the new model, respectively. Predicted mean V′_O2max was 16.5 mL/min/kg (versus observed 16.1 mL/min/kg).

6MWD and V′_O2max reveal good correlation in all models. However, the accuracy of all models is inadequate for clinical use. Thus, CPET and 6MWD both remain valuable risk assessment tools in the management of PH.

Although maximal oxygen uptake and the 6-min walk distance show good correlation in pulmonary hypertension, all predictive models are of inadequate accuracy for clinical use and cardiopulmonary exercise testing remains an irreplaceable toolhttps://bit.ly/33HBQFk

Testing of a Self-administered 6-Minute Walk Test Using Technology: Usability, Reliability and Validity Study

BACKGROUND

The need to attend a medically supervised hospital- or clinic-based appointment is a well-recognized barrier to exercise participation. The development of reliable and accurate home-based functional tests has the potential to decrease the burden on the health care system while enabling support, information, and assessment.

OBJECTIVE

This study aims to explore the usability (ie, acceptability, satisfaction, accuracy, and practicality) of the EasyMeasure app to self-administer the 6-minute walk test (6MWT) in young, healthy adults and determine parallel form reliability and construct validity of conducting a self-administered 6MWT using technology.

METHODS

We used a usability study design. English-speaking, undergraduate university students who had access to an iPhone or iPad device running iOS 10 or later and self-reported ability to walk for 6 minutes were recruited for this study. Consenting participants were randomized to either a standard 6MWT group (ie, supervised without the use of the app) or a technology 6MWT group (ie, unsupervised with the app to mimic independent implementation of the test). All participants performed a maximal treadmill test. Participants in the 6MWT group completed the Unified Theory of Acceptance and Use of Technology (UTAUT) questionnaire and a satisfaction questionnaire after completing the assessment. Parallel form reliability of the 6MWT using technology was analyzed by comparing participant self-administered scores and assessor scores using Pearson correlation coefficients across and between trials. Construct validity was assessed by comparing participant 6MWT scores (both standard and using technology) with maximum treadmill test variables (peak oxygen uptake and ventilatory threshold [VT]).

RESULTS

In total, 20 university students consented to participate in the study. All but 2 participants (8/10, 80%) in the technology 6MWT group had deviations that prevented them from accurately conducting the 6MWT using the app, and none of the participants were able to successfully score the 6MWT. However, a significantly strong correlation was found (r=.834; P=.003) when comparing participants' scores for the 6MWT using technology with the assessors' scores. No significant correlations were found between maximal treadmill test peak oxygen uptake scores and 6MWT prediction equations using standard 6MWT scores (equation 1: r=0.119; P=.78; equation 2: r=0.095; P=.82; equation 3: r=0.119; P=.78); however, standard 6MWT scores were significantly correlated with VT values (r=0.810; P=.02). The calculated submaximal treadmill scores and assessor 6MWT scores using technology also demonstrated a significant correlation (r=0.661; P=.04).

CONCLUSIONS

This study demonstrated significant usability concerns regarding the accuracy of a self-administered 6MWT using the EasyMeasure app. However, the strong and significant correlation between the 6MWT and VT values demonstrates the potential of the 6MWT to measure functional capacity for community-based exercise screening and patient monitoring.

Factors associated with lack of improvement in submaximal exercise capacity of patients with heart failure

AIMS

Improvement in exercise capacity is the primary goal of physical activity programmes for patients with heart failure (HF). Although activity programmes are effective for some patients, others do not benefit. Identifying factors related to a lack of improvement in submaximal exercise capacity may help us interpret findings and design new interventions. The aim of this study is to identify factors contributing to a lack of improvement in submaximal exercise capacity 3 months after physical activity advice or an exergame intervention in patients with HF. Additionally, we aimed to assess differences in lack of improvement in submaximal exercise capacity of patients whose baseline exercise capacity predicted a worse compared with better prognosis of HF.

METHODS AND RESULTS

This secondary analysis of the HF-Wii study analysed baseline and 3 month data of the 6 min walk test (6MWT) from 480 patients (mean age 67 years, 72% male). Data were analysed separately in patients with a pre-defined 6 min walking distance at baseline of <300 m (n = 79) and ≥300 m (n = 401). Among patients with a baseline 6MWT of ≥300 m, 18% had deteriorated submaximal exercise capacity. In the multiple logistic regression analysis, lower baseline levels of self-reported physical activity [odds ratio (OR) = 0.77, 95% confidence interval (CI) = 0.60-0.97], lower baseline levels of cognitive function (OR = 0.87, 95%CI = 0.79-0.96) were significantly associated with lack of improvement in exercise capacity at 3 months. Not randomized to exergaming (OR = 0.63, 95%CI = 0.37-1.09) was likely (P = 0.097) to be associated with lack of improvement in exercise capacity at 3 months. Among the 79 patients with baseline 6MWT of <300 m, 41% (n = 32) did not improve 6MWT distance at 3 months. Independent predictors for the lack of improvement for 6MWT were New York Heart Association class III/IV (OR = 4.68, 95%CI = 1.08-20.35), higher levels of serum creatinine (OR = 1.02, 95%CI = 1.003-1.03), lower cognitive function (OR = 0.86, 95%CI = 0.75-0.99), and fewer anxiety symptoms (OR = 0.84, 95%CI = 0.72-0.98).

CONCLUSIONS

Lower self-reported physical activity and cognitive impairment predict lack of improvement in submaximal exercise capacity in HF patients. Patients who have a worse prognosis (score <300 m at the 6MWT) are often frail and gain less in exercise capacity. These patients may need a more comprehensive approach to have an effect on exercise capacity, including an individually tailored exercise programme with aerobic exercise (if tolerated) and strength exercises.

Physical Activity and Its Association with Traditional Outcome Measures in Pulmonary Arterial Hypertension

Rationale Limitation of physical activity is a common presenting complaint for patients with pulmonary arterial hypertension (PAH). Physical activity is thought to be determined by cardiopulmonary function, yet there are limited data that investigate this relationship. Objective We aimed to study the relationship between right ventricular function and daily activity and its impact on health-related quality of life (HRQoL) in PAH. Methods Baseline data for 55 patients enrolled in PHANTOM, an ongoing multicenter randomized controlled trial of anastrozole in PAH were used. Post-menopausal women and men were eligible and underwent six-minute walk testing, echocardiography and completed HRQoL questionnaires. Each patient wore an accelerometer for 7-days. Multivariable linear regression models were used to study the association between tricuspid annular plane systolic excursion (TAPSE) and vector magnitude counts, and between daily activity and HRQoL. Principal component analysis and K-means clustering were used to identify activity-based phenotypes. K-nearest neighbors' classification was applied to an independent cross-sectional cohort from the University of Pennsylvania. Results The mean age of patients in PHANTOM was 61 years. 67% were women with idiopathic PAH as the most common etiology. A 0.4 cm increase in TAPSE was associated with an increase in daily vector magnitude counts (ß:34000, 95%CI:900-67000, p=0.004) after adjustment for age, sex, body mass index, etiology of PAH and wear time. A 1-standard deviation increase in vector magnitude counts was associated with higher six-minute walk distance (ß: 56.1 meters, 95%CI:28.6-83.7, p<0.001) and lower emPHasis-10 scores (ß:-3.3, 95%CI:0.3-6.4, p=0.03). Three activity phenotypes, low, medium, and high, were identified. The most active phenotype had greater six-minute walk distances (p=0.001) and lower emPHasis-10 scores (p=0.009) after adjustment for age, sex, body mass index, WHO functional class and parenteral prostacyclin use. Phenotypes of physical activity were reproduced in the second cohort and were independently associated with six-minute walk distance. Conclusion Better right ventricular systolic function was associated with increased levels of activity in PAH. Increased daily activity was associated with greater six-minute walk distance and better HRQoL. Distinct activity-based phenotypes may be helpful in risk stratification of PAH patients or provide novel endpoints for clinical trials.

Maximal Exercise Testing Using the Incremental Shuttle Walking Test Can Be Used to Risk-Stratify Patients with Pulmonary Arterial Hypertension

Rationale: Exercise capacity predicts mortality in pulmonary arterial hypertension (PAH), but limited data exist on the routine use of maximal exercise testing.

Objectives: This study evaluates a simple-to-perform maximal test (the incremental shuttle walking test) and its use in risk stratification in PAH.

Methods: Consecutive patients with pulmonary hypertension were identified from the ASPIRE (Assessing the Spectrum of Pulmonary hypertension Identified at a REferral centre) registry (2001–2018). Thresholds for levels of risk were identified at baseline and tested at follow-up, and their incorporation into current risk stratification approaches was assessed.

Results: Of 4,524 treatment-naive patients with pulmonary hypertension who underwent maximal exercise testing, 1,847 patients had PAH. A stepwise reduction in 1-year mortality was seen between levels 1 (≤30 m; 32% mortality) and 7 (340–420 m; 1% mortality) with no mortality for levels 8–12 (≥430 m) in idiopathic and connective tissue disease–related PAH. Thresholds derived at baseline of ≤180 m (>10%; high risk), 190–330 m (5–10%; intermediate risk), and ≥340 m (<5%; low risk of 1-yr mortality) were applied at follow-up and also accurately identified levels of risk. Thresholds were incorporated into the REVEAL (Registry to Evaluate Early and Long-Term Pulmonary Arterial Hypertension Disease Management) 2.0 risk score calculator and French low-risk approach to risk stratification, and distinct categories of risk remained.

Conclusions: We have demonstrated that maximal exercise testing in PAH stratifies mortality risk at baseline and follow-up. This study highlights the potential value of the incremental shuttle walking test as an alternative to the 6-minute walking test, combining some of the advantages of maximal exercise testing and maintaining the simplicity of a simple-to-perform field test.

The effects of high-intensity interval training, Nordic walking and moderate-to-vigorous intensity continuous training on functional capacity, depression and quality of life in patients with coronary artery disease enrolled in cardiac rehabilitation: A randomized controlled trial (CRX study)

BACKGROUND

Coronary artery disease (CAD) patients undergoing revascularization procedures often experience ongoing, diminished functional capacity, high rates of depression and markedly low quality of life (QoL). In CAD patients, studies have demonstrated that high-intensity interval training (HIIT) is superior to traditional moderate-to-vigorous intensity continuous training (MICT) for improving functional capacity, whereas no differences between Nordic walking (NW) and MICT have been observed. Mental health is equally as important as physical health, yet few studies have examined the impact of HIIT and NW on depression and QoL. The purpose of this randomized controlled trial (RCT) was to compare the effects of 12 weeks of HIIT, NW and MICT on functional capacity in CAD patients. The effects on depression severity, brain-derived neurotrophic factor (BDNF) and QoL were also examined.

METHODS

CAD patients who underwent coronary revascularization procedures were randomly assigned to: (1) HIIT (4 × 4-min of high-intensity work periods at 85%-95% peak heart rate [HR]), (2) NW (resting HR [RHR] + 20-40 bpm), or (3) MICT (RHR + 20-40 bpm) twice weekly for 12 weeks. Functional capacity (six-min walk test [6MWT]), depression (Beck Depression Inventory-II [BDI-II]), BDNF (from a blood sample), and general (Short-Form 36 [SF-36]) and disease-specific (HeartQoL) QoL were measured at baseline and follow-up. Linear mixed-effects models for repeated measures were used to test the effects of time, group and time × group interactions.

RESULTS

N = 135 CAD patients (aged 61 ± 7 years; male: 85%) participated. A significant time × group interaction (p = 0.042) showed greater increases in 6MWT distance (m) for NW (77.2 ± 60.9) than HIIT (51.4 ± 47.8) and MICT (48.3 ± 47.3). BDI-II significantly improved (HIIT: -1.4 ± 3.7, NW: -1.6 ± 4.0, MICT: -2.3 ± 6.0 points, main effect of time: p < 0.001) whereas BDNF concentrations did not change (HIIT: -2.5 ± 9.6, NW: -0.4 ± 7.7, MICT: -1.2 ± 6.4 ng/mL, main effect of time: p > 0.05). Significant improvements in SF-36 and HeartQoL values were observed (main effects of time: p < 0.05). HIIT, NW and MICT participants attended 17.7 ± 7.5, 18.3 ± 8.0 and 16.1 ± 7.3 of the 24 exercise sessions, respectively (p = 0.387).

CONCLUSIONS

All exercise programmes (HIIT, NW, MICT) were well attended, safe and beneficial in improving physical and mental health for CAD patients. NW was, however, statistically and clinically superior in increasing functional capacity, a predictor of future cardiovascular events.

Exercise intolerance in pulmonary arterial hypertension: insight into central and peripheral pathophysiological mechanisms

Exercise intolerance is a cardinal symptom of pulmonary arterial hypertension (PAH) and strongly impacts patients' quality of life (QoL). Although central cardiopulmonary impairments limit peak oxygen consumption (V' O2peak ) in patients with PAH, several peripheral abnormalities have been described over the recent decade as key determinants in exercise intolerance, including impaired skeletal muscle (SKM) morphology, convective O2 transport, capillarity and metabolism indicating that peripheral abnormalities play a greater role in limiting exercise capacity than previously thought. More recently, cerebrovascular alterations potentially contributing to exercise intolerance in patients with PAH were also documented. Currently, only cardiopulmonary rehabilitation has been shown to efficiently improve the peripheral components of exercise intolerance in patients with PAH. However, more extensive studies are needed to identify targeted interventions that would ultimately improve patients' exercise tolerance and QoL. The present review offers a broad and comprehensive analysis of the present literature about the complex mechanisms and their interactions limiting exercise in patients and suggests several gaps in knowledge that need to be addressed in the future for a better understanding of exercise intolerance in patients with PAH.

Standardized exercise training is feasible, safe, and effective in pulmonary arterial and chronic thromboembolic pulmonary hypertension: results from a large European multicentre randomized controlled trial

AIMS

This prospective, randomized, controlled, multicentre study aimed to evaluate efficacy and safety of exercise training in patients with pulmonary arterial (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS AND RESULTS

For the first time a specialized PAH/CTEPH rehabilitation programme was implemented in 11 centres across 10 European countries. Out of 129 enrolled patients, 116 patients (58 vs. 58 randomized into a training or usual care control group) on disease-targeted medication completed the study [85 female; mean age 53.6 ± 12.5 years; mean pulmonary arterial pressure 46.6 ± 15.1 mmHg; World Health Organization (WHO) functional class II 53%, III 46%; PAH n = 98; CTEPH n = 18]. Patients of the training group performed a standardized in-hospital rehabilitation with mean duration of 25 days [95% confidence interval (CI) 17-33 days], which was continued at home. The primary endpoint, change of 6-min walking distance, significantly improved by 34.1 ± 8.3 m in the training compared with the control group (95% CI, 18-51 m; P < 0.0001). Exercise training was feasible, safe, and well-tolerated. Secondary endpoints showed improvements in quality of life (short-form health survey 36 mental health 7.3 ± 2.5, P = 0.004), WHO-functional class (training vs. control: improvement 9:1, worsening 4:3; χ2P = 0.027) and peak oxygen consumption (0.9 ± 0.5 mL/min/kg, P = 0.048) compared with the control group.

CONCLUSION

This is the first multicentre and so far the largest randomized, controlled study on feasibility, safety, and efficacy of exercise training as add-on to medical therapy in PAH and CTEPH. Within this study, a standardized specialized training programme with in-hospital start was successfully established in 10 European countries.

A systematic review of exercise testing in patients with intermittent claudication: A focus on test standardisation and reporting quality in randomised controlled trials of exercise interventions

A systematic review was conducted to identify the range of terminology used in studies to describe maximum walking distance and the exercise testing protocols, and testing modalities used to measure it in patients with intermittent claudication. A secondary aim was to assess the implementation and reporting of the exercise testing protocols. CINAHL, Medline, EMBASE and Cochrane CENTRAL databases were searched. Randomised controlled trials whereby patients with intermittent claudication were randomised to an exercise intervention were included. The terminology used to describe maximal walking distance was recorded, as was the modality and protocol used to measure it. The implementation and reporting quality was also assessed using pre-specified criteria. Sixty-four trials were included in this review. Maximal walking distance was reported using fourteen different terminologies. Twenty-two different treadmill protocols and three different corridor tests were employed to assess maximal walking distance. No single trial satisfied all the implementation and reporting criteria for an exercise testing protocol. Evidence shows that between-study interpretation is difficult given the heterogenous nature of the exercise testing protocols, test endpoints and terminology used to describe maximal walking distance. This is further compounded by poor test reporting and implementation across studies. Comprehensive guidelines need to be provided to enable a standardised approach to exercise testing in patients with intermittent claudication.

Heart rate monitoring improves clinical assessment during 6-min walk

Right ventricular (RV) function is a predictor of outcomes in pulmonary arterial hypertension (PAH). The 6-min walk test (6MWT) is likely an indirect measure of RV function during exercise, but changes in absolute walk distance can also be influenced by factors like effort and musculoskeletal disease. Paired 6MWT with continuous electrocardiogram monitoring was performed in stable PAH patients, patients adding PAH therapies, and healthy controls. Heart rate expenditure (HRE) was calculated (integrating pulse during 6MWT) and then divided by walk distance (HRE/d). We also evaluated changes in peak heart rate, time above age-adjusted maximum predicted heart rate, and heart rate at 6 min. HRE/d was compared to invasive hemodynamic measures in patients who had right heart catheterization performed within seven days, WHO functional class assessment, and Emphasis 10 questionnaire. We measured two 6MWT in 15 stable PAH patients, 13 treatment intensification patients, and 8 healthy controls. HRE/d was reproducible in the stable PAH group (median difference, -0.79%), while it decreased (median difference, 23%, p = 0.0001) after adding vasodilator therapy. In 11 patients with right heart catheterization, HRE/d correlated strongly with stroke volume, r = -0.72, p = 0.01. Peak heart rate decreased after adding vasodilator therapy. HRE/d also correlated with WHO functional class and Emphasis 10 score. Continuous heart rate monitoring during 6MWT provides valuable physiologic data accounting for effort. HRE/d appears to enhance test reproducibility in stable patients while detecting change after adding therapy as compared to walk distance alone.

Short-Term Exercise Progression of Cardiovascular Patients throughout Cardiac Rehabilitation: An Observational Study

Cardiac rehabilitation (CR) is a highly recommended secondary prevention measure for patients with diagnosed cardiovascular disease. Unfortunately, participation rates are low due to enrollment and adherence issues. As such, new CR delivery strategies are of interest, as to improve overall CR delivery. The goal of the study was to obtain a better understanding of the short-term progression of functional capacity throughout multidisciplinary CR, measured as the change in walking distance between baseline six-minute walking test (6MWT) and four consecutive follow-up tests. One-hundred-and-twenty-nine patients diagnosed with cardiovascular disease participated in the study, of which 89 patients who completed the whole study protocol were included in the statistical analysis. A one-way repeated measures ANOVA was conducted to determine whether there was a significant change in mean 6MWT distance (6MWD) throughout CR. A three-way-mixed ANOVA was performed to determine the influence of categorical variables on the progression in 6MWD between groups. Significant differences in mean 6MWD between consecutive measurements were observed. Two subgroups were identified based on the change in distance between baseline and end-of-study. Patients who increased most showed a linear progression. In the other group progression leveled off halfway through rehabilitation. Moreover, the improvement during the initial phase of CR seemed to be indicative for overall progression. The current study adds to the understanding of the short-term progression in exercise capacity of patients diagnosed with cardiovascular disease throughout a CR program. The results are not only of interest for CR in general, but could be particularly relevant in the setting of home-based CR.

Overspeed Stimulus Provided by Assisted Jumping Encourages Rapid Increases in Strength and Power Performance of Older Adults

Following a 4-week control period, 24 older men and women (55-91 years) attended a 4-week progressive jumping program to determine whether assisted jumping could be safely and effectively implemented as a novel stimulus in healthy older adults. Bodyweight countermovement jump performance, isometric and isokinetic strength, postural stability, and exercise enjoyment were assessed before the control period, before the training intervention, and after the training intervention. Following the 4-week intervention, eccentric quadriceps strength increased by 19 N·m (95% confidence interval [2, 36], p = .013), bodyweight countermovement jump height increased by 1.7 cm (95% CI [0.5, 2.9], p < .001), postural sway improved by 2.1 mm/s (95% CI [0.3, 4.0], p = .026), and the participants' perceived exercise enjoyment improved (p = .026). Therefore, using assisted jumping to induce an overspeed training stimulus in a jump training program resulted in similar performance improvements as in previous studies in older populations but with less training volume and a shorter training duration.

Fick principle and exercise pulmonary hemodynamic determinants of the six-minute walk distance in pulmonary hypertension

The six-minute walk test is widely used to assess the severity and prognosis of pulmonary hypertension. However, the pathophysiology underlying a compromised six-minute walk distance is incompletely characterized. The purpose of this study is to evaluate the Fick principle and pulmonary hemodynamic determinants of the six-minute walk distance in patients with suspected pulmonary hypertension. Twenty-nine patients were retrospectively studied and underwent a right heart catheterization for the evaluation of suspected pulmonary hypertension. With the pulmonary artery catheter in place, patients were moved to a treadmill and completed a six-minute walk test. Fick cardiac output and indices of right heart afterload were calculated using continuous measurements of pulmonary vascular pressures, gas exchange, and mixed venous blood samples. Fifteen subjects who walked ≤ 348 m were compared to 14 subjects who walked > 348 m. Systemic oxygen delivery was impaired in six-minute walk distance ≤ 348 m compared to six-minute walk distance > 348 m (15.2 ± 6.2 vs. 23.2 ± 6.8 mL/kg/min, p < 0.01). Impaired oxygen delivery was due to a depressed cardiac index and decreased cardiac reserve demonstrated by the change in the stroke volume index (3.0 ± 14 vs. 17 ± 15 mL/min/m², p = 0.02). The six-minute walk distance positively correlated with oxygen delivery (r = 0.501, p = 0.006) and inversely correlated with oxygen extraction (r = 0.369, p = 0.049). A decreased six-minute walk distance was associated with an increased total pulmonary resistance (r = 0.502, p = 0.006) and pulmonary vascular resistance (r = 0.530, p = 0.003). In patients with suspected pulmonary hypertension, a decreased six-minute walk distance is due to compromised oxygen delivery, decreased cardiac reserve, and increased right ventricular afterload.

Emerging role of cardiovascular magnetic resonance imaging in the management of pulmonary hypertension

Pulmonary hypertension (PH) is a clinical condition characterised by elevation of pulmonary arterial pressure (PAP) above normal range due to various aetiologies. While cardiac right-heart catheterisation (RHC) remains the gold standard and mandatory for establishing the diagnosis of PH, noninvasive imaging of the heart plays a central role in the diagnosis and management of all forms of PH. Although Doppler echocardiography (ECHO) can measure a range of haemodynamic and anatomical variables, it has limited utility for visualisation of the pulmonary artery and, oftentimes, the right ventricle. Cardiovascular magnetic resonance (CMR) provides comprehensive information about the anatomical and functional aspects of the pulmonary artery and right ventricle that are of prognostic significance for assessment of long-term outcomes in disease progression. CMR is suited for serial follow-up of patients with PH due to its noninvasive nature, high sensitivity to changes in anatomical and functional parameters, and high reproducibility. In recent years, there has been growing interest in the use of CMR derived parameters as surrogate endpoints for early-phase PH clinical trials. This review will discuss the role of CMR in the diagnosis and management of PH, including current applications and future developments, in comparison to other existing major imaging modalities.

Physiological rationale of commonly used clinical exercise tests

In order to measure cardiopulmonary performance for clinical and investigation purposes we need standardized tests which allow the comparison with standard values, between people, or individuals with themselves over time. The quest for the ideal exercise test has led to the development of several formats, the so called laboratory and field tests. Incremental exercise tests allow measurement of maximal exercise capacity and a host of submaximal variables of great interest. The physiological rationale of the tests and of the detection of interesting submaximal variables can be explained from the oxygen uptake and carbon dioxide output kinetic response to constant power exercise. When the muscles have to produce very high energy, the exercise is physiologically limited to relatively short duration. The minimum power at which an exercise can no longer be sustained for long periods of time is called critical power. Above critical power the time-power function shows a hyperbolic shape. This shape provides the rationale for understanding the properties, limitations and responsiveness to interventions of endurance tests such as constant power test on a cycle-ergometer or treadmill, endurance shuttle walk test and six-minute walk test.

Six-minute walk distance in healthy young adults

BACKGROUND

The 6-min walk test (6MWT) is a commonly used clinical assessment of exercise capacity in patients with cardiopulmonary or neuromuscular disease, but normal values are lacking for young adults, who are frequent subjects of testing.

METHODS

In a two-center study, 272 young adults, ages 18-50, underwent American Thoracic Society protocolized 6-min walk testing, and 56 underwent repeat testing. A linear regression model was developed based on anthropomorphic data. This model was compared to existing prediction equations.

RESULTS

Median 6MWD for the cohort was 637 m (IQR 584-686 m) and was not significantly impacted by age. This is in contrast to existing equations extrapolated from older subjects that predict increasing 6MWD in younger subjects. We found weak correlation of 6MWD with height, weight, BMI, and resting heart rate. Heart rate at completion correlated most strongly with 6MWD (rho 0.53 p < 0.0001). Repeat 6MWD was surprisingly variable, with a median difference between tests of 32.5 ± 31.9 m. Established reference equations performed poorly in this population, largely because age has much less effect on 6MWD in this group than in older adults.

CONCLUSIONS

Established reference equations should be reconfigured to include data from young adults, as age has minimal effect on 6MWD in this population. Heart rate response may be a valuable measure of effort in normal subjects. Six-minute walk distance, as with pulmonary function and exercise testing, should have predictive equations across the spectrum of age to allow for accurate assessment of exercise limitation.

Longitudinal assessment of exercise capacity and quality of life outcome measures in cystic fibrosis: A year-long prospective pilot study

BACKGROUND

Multiple outcomes measures including exercise capacity and quality of life are necessary to get complete and accurate picture of cystic fibrosis (CF) progression. In this pilot study, we investigated these measures in CF longitudinally for a year to determine (a) minimal clinically important difference (MCID) for 6-minute walk distance (6MWD) and CF Health-Related Quality of Life Questionnaire (CFQ-R) domains and (b) how 6MWD, CFQ-R, and spirometry change during times of exacerbation and baseline health and their relationship among each other.

METHODS

Subjects with moderate and severe CF (baseline FEV₁ less than 70% predicted) at Akron Children's Hospital CF centre were followed for a full year longitudinally. All three tests (6MWT, CFQ-R, and spirometry) were done during each outpatient visit and weekly during inpatient admission. MCID was estimated for these parameters using distribution-based methods. Finally, data were examined visually using longitudinal graphs for each subject.

RESULTS

Twelve CF subjects (eight [67%] males and age range 13-46 years) were followed for a full year resulting in at least four encounters per subject. 6MWD (m) and CFQ-R respiratory had an MCID of 33 m and 7.3, respectively. MCIDs for FEV₁ (percentage predicted) and CFQ-R physical were 7.1 and 11.4, respectively. The longitudinal evaluation of multiple outcome measures during periods of disease exacerbation and baseline health showed that these parameters did not appear to change in accordance with each other.

CONCLUSION

In this pilot study, MCIDs for 6MWD and CFQ-R domains were calculated for the first time to facilitate their use as additional outcome measures in CF. The disparity among multiple outcome measures highlights that these measures together may provide a more complete picture in CF than any single measure alone.

Efficacy and safety of statin therapy in pulmonary hypertension: a systematic review and meta-analysis

Background

Pulmonary hypertension (PH) is a multi-causal disease and no satisfactory therapeutic strategies for it. Statins have been suggested as potential drugs in PH, whose effects in different clinic types of PH have not been conclusive. In this study, we included randomized controlled clinical trials (RCTs) evaluating the efficacy and safety of statins therapy in PH.

Methods

We searched databases including Medline, Embase, Cochrane, PubMed and Web of science, with time up to January 1, 2019. With 95% confidence interval (CI), weighted mean difference (WMD) or standardized mean difference (SMD) was pooled and calculated in a random or fixed effect model according to I2 statistic.

Results

A total of nine RCTs with 657 patients were included. Four types of statins (atorvastatin, pravastatin, rosuvastatin and simvastatin) were used at different doses (10-80 mg daily) for up to 6 months. In the pooled-data analysis, compared with placebo, there were significant improvements in pulmonary arterial pressure (PAP), in addition to low-density lipoprotein (LDL) in patients treated with statins, but not in 6-minute walking distance (6MWD), cardiac index (CDI). No more adverse events and all-cause mortality were revealed. Subgroup analysis indicated that statins could decrease PAP in the subtype of PH due to chronic obstructive pulmonary disease (COPD), but not pulmonary arterial hypertension (PAH).

Conclusions

This study indicates that statins can efficiently and safely reduce PAP in PH, especially in the subtype due to COPD. Further RCTs are needed to focus on the efficacy and safety of statin therapy in different subtypes of PH.

Counting Steps: A New Way to Monitor Patients with Pulmonary Arterial Hypertension

RATIONALE

Activity levels in patients with pulmonary arterial hypertension (PAH) have correlated with surrogate markers of disease severity. It is not known whether physical activity measures are useful in monitoring patients with PAH.

OBJECTIVES

This pilot study aimed to evaluate whether change in physical activity measured by an accelerometer correlates with changes in six-minute walk distance (6MWD), echocardiographic parameters, NT-proBNP, or health-related quality-of-life measures (HRQOL).

METHODS

The study design was a prospective, observational study in subjects with prevalent PAH. Subjects wore a wrist-worn accelerometer (Fitbit Charge HR®) between two outpatient visits. Daily step count and activity levels were recorded, and the change over time was correlated with changes in 6MWD, echocardiographic parameters, HRQOL, and NT-proBNP.

MEASUREMENTS AND MAIN RESULTS

30 subjects were enrolled, of which 20 patients had adequate accelerometer data to be analyzed over the study duration. The mean duration of follow-up was 136.4 ( ± 47.3) days. The change in daily step count correlated with a change in 6MWD (r 0.43, p 0.05). Changes in duration spent in moderately active (r 0.52, p 0.02), lightly active (r 0.48, p 0.05), and sedentary activity levels (r - 0.54, p 0.02) correlated with a change in HRQOL. Changes in activity levels did not correlate with echocardiographic measures or NT-pro BNP.

CONCLUSIONS

Changes in daily step count and time spent at fairly active, lightly active, and sedentary activity levels correlate with changes in 6MWD, and HRQOL in subjects with PAH suggesting that accelerometry may be a useful monitoring tool.

The incremental shuttle walk test predicts mortality in non-group 1 pulmonary hypertension: results from the ASPIRE Registry

Pulmonary hypertension (PH) is classified into five groups based on disease etiology but there is only limited information on the prognostic value of exercise testing in non-group 1 PH. In group 1 PH, the incremental shuttle walking test (ISWT) distance has been shown to correlate with pulmonary hemodynamics and predict survival without a ceiling effect. This study assessed the ISWT in non-group 1 PH. Data were retrieved from the ASPIRE Registry (Assessing the Spectrum of Pulmonary hypertension Identified at a REferral centre) for consecutive patients diagnosed with PH. Patients were required to have been systematically assessed as group 2-5 PH and to have a baseline ISWT within three months of cardiac catheterization. Patients were stratified according to incremental shuttle walk test distance (ISWD) and ISWT distance percent predicted (ISWD%pred). A total of 479 patients with non-group 1 PH were identified. ISWD and ISWD%pred correlated significantly with symptoms and hemodynamic severity. ISWD and ISWD%pred predicted survival with no ceiling effect. The test was prognostic in groups 2, 3, and 4. ISWD and ISWD%pred and change in ISWD and ISWD%pred at one year were all significant predictors of outcome. In patients with non-group 1 PH the ISWT is a simple non-invasive test that is easy to perform, is predictive of survival at baseline and follow-up, reflects change, and can be used in the assessment of PH of any etiology.

The added value of cardiopulmonary exercise testing in the follow-up of pulmonary arterial hypertension

BACKGROUND

The added value of cardiopulmonary exercise testing (CPET) in the follow-up of patients with stable pulmonary arterial hypertension (PAH) remains undefined.

METHODS

Idiopathic, heritable, and drug-induced PAH patients free from clinical worsening (CW) after 1 year of treatment were enrolled in derivation (n = 80) and validation (n = 80) cohorts at an interval of 6 years and followed for 3 years. Prognostic models were constructed and validated in low-risk patients in World Health Organization (WHO) Functional Class I or II with cardiac index (CI) ≥2.5 liters/min/m² and right atrial pressure (RAP) <8 mm Hg. Discrimination and calibration were assessed.

RESULTS

Forty-one derivation cohort patients had CW (51.2%) during 722 ± 349 days. Changes (∆) in WHO classification and CI and absolute value of RAP were independent predictors of CW. With addition of CPET variables, peak oxygen uptake (VO₂ peak) and ∆CI independently improved the power of the prognostic model. Receiver operating characteristic (ROC)-derived cut-off values for ∆CI and VO₂ peak were 0.40 liter/min/m² and 15.7 ml/kg/min (≥60% predicted value), respectively. Twenty-nine validation cohort patients had CW (36.2%) during 710 ± 282 days. Different combinations of cut-off values of VO₂ peak and ∆CI defined 4 groups. The event-free survival rates at 1, 2, and 3 years were 100%, 100%, and 100%, respectively, for the high ∆CI with high VO₂ peak combination; 100%, 88%, and 71% for low ∆CI/high VO₂ peak; 80%, 54%, and 40% for high ∆CI/low VO₂ peak; and 72%, 54%, and 33% for low ∆CI/low VO₂ peak.

CONCLUSIONS

The combinations of baseline VO₂ peak and change in CI during follow-up is important in prognostication of low-risk patients with idiopathic, heritable, and drug-induced PAH.

Dichotomous Locomotor Recoveries Are Predicted by Acute Changes in Segmental Blood Flow after Thoracic Spinal Contusion Injuries in Pigs

Neuroimaging facilitates the translation of animal pre-clinical research to human application. The large porcine spinal cord is useful for testing invasive interventions. Ideally, the safety and efficacy of a delayed intervention is tested in pigs that have recovered sufficiently after spinal cord injury (SCI) to allow either deterioration or improvement of function to be detected. We set out to create moderate severity T9 injuries in Yucatan minipigs by conducting a bridging study adapting methods previously developed in infant piglets. The injury severity was varied according to two pneumatic impactor parameters: the piston compression depth into tissue or the velocity. To stratify locomotor recovery, a 10-point scale used in prior piglet studies was redefined through longitudinal observations of spontaneous recovery. Using hindlimb body weight support to discriminate injury severity, we found that end-point recovery was strongly bimodal to either non-weight-bearing plegia with reciprocating leg movements (<5/10) or recovery of weight bearing that improved toward a ceiling effect (≥ 8/10). No intermediate recovery animals were observed at 2 months post-injury. The ability of intra-operative ultrasound and acute magnetic resonance imaging (MRI) to provide immediate predictive feedback regarding tissue and vascular changes following SCI was assessed. There was an inverse association between locomotor outcome and early gray matter hemorrhage on MRI and ultrasound. Epicenter blood flow following contusion predicted recovery or non-recovery of weight-bearing. The depth of the dorsal cerebrospinal fluid space, which varied between animals, influenced injury severity and confounded the results in this fixed-stroke paradigm.

Effects and moderators of exercise on muscle strength, muscle function and aerobic fitness in patients with cancer: a meta-analysis of individual patient data

Objective

To optimally target exercise interventions for patients with cancer, it is important to identify which patients benefit from which interventions.

Design

We conducted an individual patient data meta-analysis to investigate demographic, clinical, intervention-related and exercise-related moderators of exercise intervention effects on physical fitness in patients with cancer.

Data sources

We identified relevant studies via systematic searches in electronic databases (PubMed, Embase, PsycINFO and CINAHL).

Eligibility criteria

We analysed data from 28 randomised controlled trials investigating the effects of exercise on upper body muscle strength (UBMS) and lower body muscle strength (LBMS), lower body muscle function (LBMF) and aerobic fitness in adult patients with cancer.

Results

Exercise significantly improved UBMS (β=0.20, 95% Confidence Interval (CI) 0.14 to 0.26), LBMS (β=0.29, 95% CI 0.23 to 0.35), LBMF (β=0.16, 95% CI 0.08 to 0.24) and aerobic fitness (β=0.28, 95% CI 0.23 to 0.34), with larger effects for supervised interventions. Exercise effects on UBMS were larger during treatment, when supervised interventions included ≥3 sessions per week, when resistance exercises were included and when session duration was >60 min. Exercise effects on LBMS were larger for patients who were living alone, for supervised interventions including resistance exercise and when session duration was >60 min. Exercise effects on aerobic fitness were larger for younger patients and when supervised interventions included aerobic exercise.

Conclusion

Exercise interventions during and following cancer treatment had small effects on UBMS, LBMS, LBMF and aerobic fitness. Demographic, intervention-related and exercise-related characteristics including age, marital status, intervention timing, delivery mode and frequency and type and time of exercise sessions moderated the exercise effect on UBMS, LBMS and aerobic fitness.

The effect of interactive digital interventions on physical activity in people with inflammatory arthritis: a systematic review

The aim of this systematic review was to evaluate the evidence from randomised controlled trials (RCTs) evaluating the effectiveness of interactive digital interventions (IDIs) for physical activity (PA) and health related quality of life (HRQoL) in people with Inflammatory Arthritis [rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA) axial Spondyloarthritis (AS) and psoriatic arthritis (PsA)]. Seven electronic databases identified published and unpublished studies. Two reviewers conducted independent data extraction and quality assessment using the Cochrane risk of bias tool (RoB). The primary outcome was change in objective PA after the intervention; secondary outcomes included self-reported PA and HRQoL after the intervention and objective or self-reported PA at least 1 year later. Five manuscripts, reporting four RCTs (three high and one low RoB) representing 492 (459 RA, 33 JIA) participants were included. No trials studying PsA or AS met the inclusion criteria. Interventions ranged from 6 to 52 weeks and included 3-18 Behaviour Change Techniques. Due to heterogeneity of outcomes, a narrative synthesis was conducted. No trials reported any significant between group differences in objective PA at end of intervention. Only one low RoB trial found a significant between group difference in self-reported vigorous [MD Δ 0.9 days (95% CI 0.3, 1.5); p = 0.004], but not moderate, PA in people with RA but not JIA. There were no between group differences in any other secondary outcomes. There is very limited evidence for the effectiveness of IDIs on PA and HRQoL in RA and JIA and no evidence for their effectiveness in PsA or AS.

Transition from Ambrisentan to Bosentan in Pulmonary Arterial Hypertension: A Single-Center Prospective Study

Background and objective: Two endothelin receptor antagonists (ETRAs), bosentan and ambrisentan, are approved for patients with pulmonary arterial hypertension (PAH). However, there is little information about the transition strategy between these two ETRAs. We aimed to evaluate the safety and efficacy from ambrisentan to bosentan. Methods: Twenty PAH patients were enrolled into the single-center, open-labelled prospective study. Echocardiogram, WHO functional class (WHO-FC), 6-minute walking distance (6MWD), right heart catheterization, and hemotology were collected. After receiving oral 5 mg ambrisentan daily initially for one year, the patients were divided into two arms: eight patients switched to bosentan, while the remaining 12 patients continued ambrisentan. Characteristics at baseline, 1-and 2-year follow-up points were compared.

RESULTS

There were no significant differences in echocardiogram, WHO-FC, hemodynamics, demographics and liver function at baseline, 1-and 2-year points in both arms. 6MWD in bosentan group was significantly shorter at baseline. But there were no significant differences of 6MWD at 1- and 2-year points.

CONCLUSIONS

It is safe for stable PAH patients to transition from ambrisentan to bosentan without hemodynamic or hematologic deterioration.

Modeling of pharmacokinetics, efficacy, and hemodynamic effects of macitentan in patients with pulmonary arterial hypertension

BACKGROUND

Macitentan is the first endothelin receptor antagonist with demonstrated efficacy on morbidity and mortality in pulmonary arterial hypertension (PAH) in the pivotal study SERAPHIN.

METHODS

The pharmacokinetics (PK) of macitentan and its active metabolite, ACT-132577, were characterized in a population model. Efficacy and hemodynamics (pharmacodynamics, PD) were related to PK based on PK/PD modeling.

RESULTS

Sex, age, and body weight influenced the PK to a statistically significant extent. Model-based simulations showed that these variables are clinically not relevant. Concomitant use of PAH medication (PDE-5 inhibitors) did not influence macitentan trough concentration to a relevant extent. Efficacy and hemodynamics showed clear differences from placebo for macitentan concentrations on 3 and 10 mg with consistent superior effects for 10 mg. After 6 months, PAH patients showed model-predicted 6-min walk distance (6-MWD) improvements of 1.0 m on placebo compared to 29.8 and 34.1 m on 3 and 10 mg of macitentan, respectively. Higher macitentan concentrations were associated with reductions in pulmonary vascular resistance (PVR), mean right atrial and pulmonary arterial pressure, and total pulmonary resistance (TPR) and increases in cardiac index (CI) and mixed venous oxygen saturation. Statistical significance was determined for PVR, TPR, and CI but not for 6-MWD. In addition, PVR showed more pronounced differences between active treatment and placebo than 6-MWD.

CONCLUSIONS

Modeling identified statistically significant inter-patient differences; simulations to assess the magnitude of the effects permitted clinical judgment. The same approach will allow for extrapolation to children. Hemodynamic markers might be better markers of treatment effects than 6-MWD.

TRIAL REGISTRATION

The SERAPHIN study and its open-label extension are registered with ClinicalTrials.gov with identifiers NCT00660179 (https://www.clinicaltrials.gov/ct2/show/NCT00660179) and NCT00667823 (https://clinicaltrials.gov/ct2/show/NCT00667823) and with EudraCT with identifiers 2007-002440-14 (https://www.clinicaltrialsregister.eu/ctr-search/search?query=2007-002440-14) and 2007-003694-27 (https://www.clinicaltrialsregister.eu/ctr-search/search?query=2007-003694-27).

Physical Functioning and Symptoms of Chronic Fatigue in Sarcoidosis Patients

Scientific reports underscore the importance of measuring the health-related quality of life in sarcoidosis patients. The present study seeks to define how sarcoidosis patients' quality of life, daily physical activity, and physical performance are related to each other. Seventeen patients (mean age 46.8 ± 8.8 years) suffering from sarcoidosis completed the following questionnaires: the fatigue assessment scale (FAS), the quality of life scale (SF-36 questionnaire), and the Borg dyspnea scale. Physical activity (PA) was assessed using accelerometry. Respiratory function, consisting of forced expiratory volume in one second (FEV1), forced vital capacity (FVC), forced expiratory volume in one second as a percentage of vital capacity (FEV1/%FVC), and diffusing capacity of the lungs for carbon monoxide (DLCO), were assessed. In addition, performance in 6-min walk test (MWT), aerobic capacity assessed from maximal oxygen uptake (VO2max), and the metabolic equivalent of task (MET) were evaluated. We found that daily PA (4566 ± 2378 steps/day) and VO2max (21.8 ± 5.9 ml/kg/min) were lower in sarcoidosis patients than the known predicted values in healthy age-matched individuals. There were significant inverse associations between the FAS score and 6MWT (r = -0.62; p < 0.01), and between SF-36 score and 6MWT (r = -0.55; p < 0.03). In contrast, SF-36 scores associated with fatigue and dyspnea scores (r = 0.72; p < 0.001 and r = 0.85; p < 0.001). These findings imply that sarcoidosis patients are less active compared with healthy subjects. The FAS and SF-36 scales seem to be effective tools for assessing the severity of fatigue in sarcoidosis patients.

A prescribed walking regimen plus arginine supplementation improves function and quality of life for patients with pulmonary arterial hypertension: a pilot study

Current evidence suggests that exercise training is beneficial in pulmonary arterial hypertension (PAH). Unfortunately, the standard supervised, hospital-based programs limit patient accessibility to this important intervention. Our proof-of-concept study aimed to provide insight into the usefulness of a prescribed walking regimen along with arginine supplementation to improve outcomes for patients with PAH. Twelve PAH patients (all women) in New York Heart Association (NYHA) functional class (FC) II (n = 7) or III (n = 5) and in stable condition for ≥ 3 months were enrolled. Patients performed home- and fitness-center- based walking at 65-75% heart rate (HR) reserve for 45 min, six sessions/week for 12 weeks. Concomitant L-arginine supplementation (6000 mg/day) was provided to maximize beneficial endothelial training adaptations. Cardiopulmonary exercise testing, 6-min walk testing (6MWT), echocardiography, laboratory studies, and quality of life (QoL) survey (SF-36) were performed at baseline and 12 weeks. Eleven patients completed the study (72 session adherence rate = 96 ± 3%). Objective improvement was demonstrated by the 6MWT distance (increased by 40 ± 13 m, P = 0.01), VO₂max (increased by 2 ± 0.7 mL/kg/min, P = 0.02), time-to-VO₂max (increased by 2.5 ± 0.6 min, P = 0.001), VO₂ at anaerobic threshold (increased by 1.3 ± 0.5 mL/kg/min, P = 0.04), HR recovery (reduced by 68 ± 23% in slope, P = 0.01), and SF-36 subscales of Physical Functioning and Energy/Fatigue (increased by 70 ± 34% and 74 ± 34%, respectively, P < 0.05). No adverse events occurred, and right ventricular function and brain natriuretic peptide levels remained stable, suggesting safety of the intervention. This proof-of-concept study indicates that a simple walking regimen with arginine supplementation is a safe and efficacious intervention for clinically stable PAH patients, with gains in objective function and QoL measures. Further investigation in a randomized controlled trial is warranted.

Effect of a 6-month pedometer-based walking intervention on functional capacity in patients with chronic heart failure with reduced (HFrEF) and with preserved (HFpEF) ejection fraction: study protocol for two multicenter randomized controlled trials

Background

Regular physical activity is recommended for patients with chronic heart failure to improve their functional capacity, and walking is a popular, effective, and safe form of physical activity. Pedometers have shown potential to increase the amount of walking across a range of chronic diseases, but it is unknown whether a pedometer-based intervention improves functional capacity and neurohumoral modulation in heart failure patients.

Methods

Two multicenter randomized controlled trials will be conducted in parallel: one in patients with chronic heart failure with reduced ejection fraction (HFrEF), the other in patients with chronic heart failure with preserved ejection fraction (HFpEF). Each trial will consist of a 6-month intervention with an assessment at baseline, at 3 months, at the end of the intervention, and 6 months after completing the intervention. Each trial will aim to include a total of 200 physically inactive participants with chronic heart failure who will be randomly assigned to intervention or control arms. The 6-month intervention will consist of an individualized pedometer-based walking program with weekly step goals, behavioral face-to-face sessions with a physician, and regular telephone calls with a research nurse. The intervention will be based on effective behavioral principles (goal setting, self-monitoring, personalized feedback). The primary outcome is the change in 6-min walk distance at the end of the 6-month intervention. Secondary outcomes include changes in serum biomarkers levels, pulmonary congestion assessed by ultrasound, average daily step count measured by accelerometry, anthropometric measures, symptoms of depression, health-related quality of life, self-efficacy, and MAGGIC risk score.

Discussion

To our knowledge, these are the first studies to evaluate a pedometer-based walking intervention in patients with chronic heart failure with either reduced or preserved ejection fraction. The studies will contribute to a better understanding of physical activity promotion in heart failure patients to inform future physical activity recommendations and heart failure guidelines.

Trial registration The trials are registered in ClinicalTrials.gov, identifiers: NCT03041610, registered 29 January 2017 (HFrEF), NCT03041376, registered 1 February 2017 (HFpEF)

Combination therapy in pulmonary arterial hypertension: recent accomplishments and future challenges

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by a progressive increase in pulmonary vascular resistance, ultimately leading to right heart failure and death. Throughout the past 20 years, numerous specific pharmacologic agents, including phosphodiesterase-5 inhibitors, endothelin receptor antagonists, prostaglandins, and more recently, soluble guanylate cyclase stimulators and selective IP prostacyclin receptor agonist, have emerged for the treatment of PAH. Early clinical trials were typically of short-term duration, comparing the effects of PAH-targeted therapies versus placebo and using exercise tolerance as the primary endpoint in most trials. A meta-analysis of these trials documented a reduction in short-term mortality of ∼40% with monotherapy. More recently, we have witnessed a progressive shift in PAH study designs using longer event-driven trials comparing the effects of upfront and sequential combination therapy on clinical worsening that is perceived as a more clinically relevant outcome measure. Recent meta-analyses also documented that combination therapy significantly reduced the risk of clinical worsening by ∼35% compared with monotherapy alone.

In this review article, we will discuss the evolution of treatments and clinical trial design in the field of PAH over the past decades with a special focus on combination therapy and its current role in the management of PAH. We will also detail unresolved questions regarding the future of PAH patients’ care and the challenges of future clinical trials.