Maximal cardiac output determines 6 minutes walking distance in pulmonary hypertension

SPECTRA Phase 2b Study: Impact of Sotatercept on Exercise Tolerance and Right Ventricular Function in Pulmonary Arterial Hypertension

BACKGROUND

This study aims to assess the impact of sotatercept on exercise tolerance, exercise capacity, and right ventricular function in pulmonary arterial hypertension.

METHODS

SPECTRA (Sotatercept Phase 2 Exploratory Clinical Trial in PAH) was a phase 2a, single-arm, open-label, multicenter exploratory study that evaluated the effects of sotatercept by invasive cardiopulmonary exercise testing in participants with pulmonary arterial hypertension and World Health Organization functional class III on combination background therapy. The primary end point was the change in peak oxygen uptake from baseline to week 24. Cardiac magnetic resonance imaging was performed to assess right ventricular function.

RESULTS

Among the 21 participants completing 24 weeks of treatment, there was a significant improvement from baseline in peak oxygen uptake, with a mean change of 102.74 mL/min ([95% CIs, 27.72-177.76]; P=0.0097). Sotatercept demonstrated improvements in secondary end points, including resting and peak exercise hemodynamics, and 6-minute walk distance versus baseline measures. Cardiac magnetic resonance imaging showed improvements from baseline at week 24 in right ventricular function.

CONCLUSIONS

The clinical efficacy and safety of sotatercept demonstrated in the SPECTRA study emphasize the potential of this therapy as a new treatment option for patients with pulmonary arterial hypertension. Improvements in right ventricular structure and function underscore the potential for sotatercept as a disease-modifying agent with reverse-remodeling capabilities.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03738150.

Therapeutic Effects of Intradialytic Exercise on Life Quality of Patients with End-Stage Renal Disease: Study Protocol for a Randomized Control Trial

Background: Exercise training has positive effects on physical functions and could reduce a sedentary lifestyle for hemodialysis (HD) patients. Given that low-level physical activity increases morbidity and mortality, here, we aimed to determine the effects of an intradialytic exercise program delivered at different frequencies on HD patients in Taiwan. Methods: This study is a prospective, randomized control trial. An intradialytic exercise program will be arranged for patients after receiving their informed consent. Patients will be segregated at random into three groups as follows: (a) three times/week of intradialytic exercise training plus standard care maintenance of HD, (b) two times/week of intradialytic exercise training plus standard care maintenance of HD, or (c) standard care maintenance of HD. Subjects will be followed for 24 weeks. At three time points, 0, 12, and 24 weeks, the primary outcome, the Short-Form 36 score, will be measured. Additional secondary outcomes to be measured are the Beck depression inventory, 6 min walking test, sit-to-stand test, and anthropometric measures such as the body mass index, thigh circumference, and the proportion of fat in the body composition. Conclusions: There is emerging evidence in support of intradialytic exercise improving health-related quality of life for patients on HD. However, the difference in the therapeutic effects between three times per week and twice per week has never been determined. With this study, we anticipate to fill the knowledge gap in the exercise prescription among HD patients.

Oates K, J. Fletcher A, P. Sylvester K. The association of six-minute walk work and other clinical measures to cardiopulmonary exercise test parameters in pulmonary vascular disease

INTRODUCTION

In pulmonary vascular disease exercise, abnormalities can include reduced exercise capacity, reduced oxygen pulse and elevated VE/VCO2. The association of clinical measures such as six-minute walk work, haemodynamics, lung function and echocardiogram to peak VO2, O2 pulse and VE/VCO2 has not been fully investigated in pulmonary vascular disease.

AIMS

To determine the relationship of six-minute walk work and other clinical measures to peak VO2, peak O2 pulse and VE/VCO2. Additionally, to investigate the ability to predict peak VO2 from six-minute walk work and other clinical parameters.

METHODS

Clinical data was retrospectively analysed from 63 chronic thromboembolic pulmonary hypertension (CTEPH) and 54 chronic thromboembolic disease (CTED) patients. Six-minute walk test measures, haemodynamics, lung function and echocardiographic measures were correlated with peak VO2, peak O2 pulse and VE/VCO2. Predictive equations were developed to predict peak V̇O2 in both CTEPH and CTED cohorts and subsequently validated.

RESULTS

A number of clinical parameters correlated to peak VO2, peak O2 pulse and VE/VCO2. Six-minute walk work and transfer factor for carbon monoxide demonstrated the strongest correlation to peak VO2 and peak O2 pulse. The validation of the predictive equations showed a variable level of agreement between measured peak VO2 and calculated peak VO2 from the predictive equations.

CONCLUSION

Six-minute walk work and additionally a number of clinical test parameters were associated to peak VO2, peak O2 pulse and VE/VCO2. Six-minute walk work and transfer factor for carbon monoxide were particularly highly correlated to peak VO2 and similarly to peak oxygen pulse. The validation of the predictive equations showed a variable level of agreement and therefore may have limited clinical applicability.

A more effective alternative to the 6-minute walk test for the assessment of functional capacity in patients with pulmonary hypertension

BACKGROUND

The prognosis of Pulmonary Hypertension (PH) is directly correlated with the functional capacity (FC). The most common FC test is the 6-Minute Walk Test (6MWT), however, there is evidence to suggest that the 6MWT does not reflect the real FC in PH patients.

OBJECTIVE

To compare physiological responses among three field walk tests and cardiopulmonary exercise testing (CPET) in patients with pulmonary hypertension (PH), and to determine the determinants of distance walked in the field walk tests.

DESIGN

Cross sectional.

SETTING

Outpatient clinic.

PARTICIPANTS

26 volunteers (49.8 ± 14.6 years), WHO functional class II-III and a mean pulmonary artery pressure of 45 mmHg.

INTERVENTIONS

Patients underwent three field walk test: 6MWT, incremental shuttle walk test (ISWT), and endurance shuttle walk test (ESWT) and CPET on different, nonconsecutive days.

MAIN OUTCOME MEASURES

Heart rate and perception of effort at the peak of exercise.

RESULTS

The ISWT achieved maximum levels of effort without significant difference in any physiologic response compared to CPET. The physiological responses during ISWT were significantly higher than 6MWT and ESWT responses.

CONCLUSIONS

The ISWT produced the greatest physiologic response of the field tests safely for which reason it appears to be the most effective test to assess FC of PH patients.

Cor pulmonale: the role of traditional and advanced echocardiography in the acute and chronic settings

Cor pulmonale is the condition in which the right ventricle undergoes morphological and/or functional changes due to diseases that affect the lungs, the pulmonary circulation, or the breathing process. Depending on the speed of onset of the pathological condition and subsequent effects on the right ventricle, it is possible to distinguish the acute cor pulmonale from the chronic type of disease. Echocardiography plays a central role in the diagnostic and therapeutic work-up of these patients, because of its non-invasive nature and wide accessibility, providing its greatest usefulness in the acute setting. It also represents a valuable tool for tracking right ventricular function in patients with cor pulmonale, assessing its stability, deterioration, or improvement during follow-up. In fact, not only it provides parameters with prognostic value, but also it can be used to assess the efficacy of treatment. This review attempts to provide the current standards of an echocardiographic evaluation in both acute and chronic cor pulmonale, focusing also on the findings present in the most common pathologies causing this condition.

Modulation of left ventricular diastolic filling during exercise in persons with cervical motor incomplete spinal cord injury

PURPOSE

To characterize left ventricular diastolic function during an exertional challenge in adults with incomplete cervical spinal cord Injury (icSCI).

METHODS

In this cross-sectional study, a two-group convenience sample was used to compare left ventricular LV diastolic performance during a 5-10 W·min-1 incremental arm ergometer exercise protocol, using bioimpedance cardiography. Subjects were eight males with cervical incomplete spinal cord injury (icSCI; C5-C7: age 39 ± 14 years) versus eight able-bodied males (CON: age 38 ± 13 years). Left ventricular (LV) diastolic indices included end-diastolic volume (EDV) and early diastolic filling ratio (EDFR). LV ejection time (LVET), inotropic index (dZ/dT2) and stroke volume (SV) were compared between the groups at peak exercise, and maximum workload for the icSCI group (isomax).

RESULTS

EDV (at peak exercise:131.4 ± 7.3 vs 188.78 ± 9.4, p < 0.001; at isomax: 131.4 ± 7.3 vs 169 ± 23, p = 0.0009) and EDFR (at peak exercise 73 ± 14% vs 119 ± 11%, p = 0.006; at isomax 94 ± 10; p = 0.009) were significantly reduced in icSCI compared to CON, respectively. Significant differences in LVET (icSCI: 273 ± 48 vs CON: 305 ± 68; p = 0.1) and dZ/dT2 (icSCI: 0.64 ± 0.11 vs CON: 0.85 ± 0.31; p = 0.1) were not observed at isomax, despite a significant decrease in SV in the subjects with icSCI (77.1 ± 6.05 mL vs 105.8 ± 9.2 mL, p < 0.00) CONCLUSION: Left ventricular filling was impaired in the subjects with icSCI as evidenced at both peak exercise and isomax. It is likely that restrictions on the skeletal muscle pump mechanized the impairment but increased left ventricular wall stiffness could not be excluded as a mediator.

Guideline implementation and early risk assessment in pulmonary arterial hypertension associated with congenital heart disease: A retrospective cohort study

INTRODUCTION

Current guidelines emphasize that accurate risk stratification is important for patients with pulmonary arterial hypertension (PAH), however, few suggestions have been specified for PAH associated with congenital heart disease (PAH-CHD).

OBJECTIVES

The aim of this study was to propose an accurate and simple system based on current guidelines for risk stratification in PAH-CHD patients during 12-month follow-up.

METHODS

We reviewed 288 Chinese PAH-CHD patients between January 2014 and December 2016 in this retrospective cohort study. The low-risk criteria according to 2015 European Society of Cardiology guidelines and the adverse events (AEs) during follow-up were collected. The association between low-risk criteria and AEs was assessed with Cox regression, and a simplified risk stratification system was proposed.

RESULTS

There were 105 PAH-CHD patients included in the final analysis. Twenty-nine patients had AEs defined as death, initiation of new or combined medication treatment, or re-hospitalisation because of the PAH worsening. Among the low-risk criteria, WHO/NYHA functional class, 6-minute walking distance (6MWD), NT-proBNP and SvO₂ were significantly different between AE and AE-free groups. However, 6MWD (HR = 0.08, 95% CI: 0.03-0.19, P < 0.001) and NT-proBNP (HR = 0.35, 95% CI: 0.16-0.78, P = 0.01) were the only independent predictors of AEs in multivariable model. When taking them into a simplified system for risk stratification, the number of low-risk criteria at diagnosis discriminated the risk of AEs (P < 0.001).

CONCLUSIONS

Among the low-risk criteria proposed by current guidelines, 6MWD and NT-proBNP predicted AEs independently for PAH-CHD patients. Simplified risk stratification system by taking these two parameters numerically provides accurate prognostic information in PAH-CHD patients.

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.

Right Ventricular Functional Reserve in Early-Stage Idiopathic Pulmonary Fibrosis: An Exercise Two-Dimensional Speckle Tracking Doppler Echocardiography Study

BACKGROUND

The most important determinant of long-term survival in patients with idiopathic pulmonary fibrosis is the right ventricular (RV) adaptation to the increased pulmonary vascular resistance. Our aim was to explore RV contractile reserve during stress echocardiography in early-stage IPF.

METHODS

Fifty early-stage patients with IPF and 50 healthy control patients underwent rest and stress echocardiography, including RV two-dimensional speckle tracking echocardiography. At peak exertion, blood gas analysis and spirometry were also assessed.

RESULTS

At rest, RV diameters were mildly increased in IPF; however, although RV conventional systolic function indexes were similar between the IPF and control groups, RV global longitudinal strain and RV lateral wall longitudinal strain (LWLS) were significantly reduced in the IPF cohort. During physical exercise, patients with IPF showed a reduced exercise tolerance with lower maximal workload (P < .01), level of oxygen saturation (P < .001), and peak heart rate (P < .01). Systolic and diastolic BP values were similar in both groups. Systolic pulmonary artery pressure (PAPs) increase (ΔPAPs) during exertion was higher in IPF vs healthy subjects (P < .0001); RV LWLS increase (ΔRV LWLS) during exercise was lower in patients with IPF vs control patients (P < .00001). By multivariable analysis, RV LWLS at rest and ΔRV LWLS were directly related to peak exertion capacity, PAPs, and blood oxygen saturation level (Spo₂; P < .0001). Δ RV LWLS was directly related to diffusion lung carbon monoxide (P < .0001).

CONCLUSIONS

RV myocardial dysfunction is already present at rest in early-stage IPF and worsens during exertion as detected by two-dimensional speckle-tracking echocardiography. The RV altered contractile reserve appears to be related to reduced exercise tolerability and impaired pulmonary hemodynamic.

Incremental Shuttle Walking Test Distance Is Reduced in Patients With Pulmonary Hypertension in World Health Organisation Functional Class I

Background: There is increasing interest in screening for and diagnosing pulmonary hypertension earlier in the course of disease. However, there is limited data on cardiopulmonary abnormalities in patients with pulmonary hypertension newly diagnosed in World Health Organization Function Class (WHO FC) I. Methods: Data were retrieved from the ASPIRE registry (Assessing the Spectrum of Pulmonary hypertension Identified at a REferral center) for consecutive treatment naïve patients diagnosed with pulmonary hypertension by cardiac catheterization between 2001 and 2010 who underwent incremental shuttle walk exercise testing. Results: Eight hundred and ninety-five patients were diagnosed with Group 1-5 pulmonary hypertension. Despite the absence of symptoms, patients in WHO FC I (n = 9) had a significant reduction in exercise capacity (Incremental shuttle walk distance percent predicted (ISWD%pred) 65 ± 13%, Z score -1.77 ± 1.05), and modest pulmonary hypertension with a median (interquartile range) pulmonary artery pressure 31(20) mmHg and pulmonary vascular resistance 2.1(8.2) Wood Units, despite a normal diffusion of carbon monoxide adjusted for age and sex (DLco)%pred 99 ± 40%. Compared to patients in WHO FC I, patients in WHO FC II (n = 162) had a lower ISWD%pred 43 ± 22 and lower DLco%pred 65 ± 21%. Conclusion: Our results demonstrate that patients with newly diagnosed pulmonary hypertension with no or minimal symptomatic limitation have a significant reduction of exercise capacity.

Cardiopulmonary factors affecting 6-min walk distance in patients with idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies involve skeletal muscles and can be associated with interstitial lung disease and/or heart dysfunction, which may reduce exercise capacity. We aimed to clarify cardiopulmonary factors affecting the 6-min walk distance in patients who were able to walk without leg pain or fatigue. Twenty-three patients with inactive adult idiopathic inflammatory myopathies, and 18 age- and gender-matched healthy controls were evaluated for hemodynamic responses using noninvasive impedance cardiography during the 6-min walk test. The patients were also examined by the pulmonary function test for forced vital capacity and diffusing capacity for carbon monoxide (DLCO), and by echocardiography for left ventricular ejection fraction and right ventricular systolic pressure. Interstitial lung disease was diagnosed in 19 patients using high-resolution computed tomography. There was no difference in 6-min walk distance or cardiac output after walking between the patients and healthy controls. However, stroke volume during the 6-min walk test was significantly lower in the patients than in healthy controls, suggesting malfunction in the heart. Moreover, the increased heart rate matched the cardiac output. Spearman’s correlation analysis demonstrated a correlation between 6-min walk distance and stroke volume, cardiac output after walking and DLCO, but not left ventricular ejection fraction or right ventricular systolic pressure, as this study lacked the patients with pulmonary hypertension. In conclusion, impaired DLCO due to interstitial lung disease was suggested to be a fundamental parameter affecting exercise capacity, in addition to heart involvement, in patients with idiopathic inflammatory myopathies.

Association between six-minute walk distance and long-term outcomes in patients with pulmonary arterial hypertension: Data from the randomized SERAPHIN trial

BACKGROUND

Patients with pulmonary arterial hypertension who achieve a six-minute walk distance of 380-440 m may have improved prognosis. Using the randomized controlled trial of macitentan in pulmonary arterial hypertension (SERAPHIN), the association between six-minute walk distance and long-term outcomes was explored.

METHODS

Patients with six-minute walk distance data at Month 6 were dichotomized as above or below the median six-minute walk distance (400 m) and assessed for future risk of pulmonary arterial hypertension-related death or hospitalization and all-cause death. Additionally, six-minute walk distance values at baseline, Month 6 and the change from baseline to Month 6 were categorized by quartiles. All associations were analyzed by the Kaplan-Meier method using a log-rank test and Cox regression models.

RESULTS

Patients with a six-minute walk distance >400 m vs. ≤400 m at Month 6 have a reduced risk of pulmonary arterial hypertension-related death or hospitalization (hazard ratio 0.48; 95% confidence interval 0.33-0.69). The risk was also lower for patients with higher quartiles of six-minute walk distance at baseline or Month 6 (baseline: hazard ratio [Q4 (>430 m) vs. Q1 (≤300 m)] 0.23; 95% confidence interval 0.15-0.36; Month 6: hazard ratio [Q4 (>455 m) vs. Q1 (≤348 m)] 0.33; 95% confidence interval 0.19-0.55). In contrast, six-minute walk distance changes at Month 6 were not associated with the risk of pulmonary arterial hypertension-related death or hospitalization (p = 0.477). These findings were consistent when adjusted for known confounders. Similar results were observed for the risk of all-cause death up to end of study.

CONCLUSIONS

Patients with pulmonary arterial hypertension walking >400 m had better long-term prognosis. Although changes in six-minute walk distance were not associated with long-term outcomes, assessing absolute six-minute walk distance values remains important in the clinical management of patients with pulmonary arterial hypertension.

Echocardiographic Predictors for Worsening of Six-Minute Walk Distances in Patients With Systemic Sclerosis (Scleroderma)

Change in 6-minute walk distance (6MWD) has been used as a clinical marker in pulmonary hypertension. Determinants and worsening of 6MWD remain a matter of debate because nonpulmonary factors have an impact on the 6MWD. We hypothesized that future reduction of 6MWD in patients with systemic sclerosis (SSc) was more closely associated with cardiac dysfunction. We prospectively performed standard clinical and echocardiographic evaluations in SSc patients with the 6-minute walk test at enrollment. Features associated with the 6MWD were sought in a multiple linear regression analysis and compared using standardized β. Worsening of the 6MWD was defined as a 15% reduction and served as the primary outcome. Eighty-one patients were included. In the multivariate analysis, baseline 6MWD was related to SSc severity score (β = -0.250, p = 0.024), left atrial volume index (β = -0.222, p = 0.046), right ventricular fractional area change (β = 0.252, p = 0.025), and the ratio of mean pulmonary artery pressure and cardiac output (β = -0.31, p = 0.002). During follow-up, 20 patients reached the primary outcome. In sequential Cox models, a model based on right ventricular fractional area change at baseline (chi-square 4.8) was improved by left atrial volume index (chi-square 10.3, p = 0.007). In conclusion, determinants and worsening of 6MWD are explained by cardiac factors. When using the 6MWD as a clinical marker in pulmonary hypertension patients, their left ventricular diastolic function and right ventricular systolic function should be taken into consideration.

Incremental shuttle walk test distance and autonomic dysfunction predict survival in pulmonary arterial hypertension

BACKGROUND

To ensure effective monitoring of pulmonary arterial hypertension (PAH), a simple, reliable assessment of exercise capacity applicable over a range of disease severity is needed. The aim of this study was to assess the ability of the incremental shuttle walk test (ISWT) to correlate with disease severity, measure sensitivity to change, and predict survival in PAH.

METHODS

We enrolled 418 treatment-naïve patients with PAH with baseline ISWT within 3 months of cardiac catheterization. Clinical validity and prognostic value of ISWT distance were assessed at baseline and 1 year.

RESULTS

ISWT distance was found to correlate at baseline with World Health Organization functional class, Borg score, and hemodynamics without a ceiling effect (all p < 0.001). Walking distance at baseline and after treatment predicted survival; the area under the receiver operating characteristic curve for ability of ISWT distance to predict mortality was 0.655 (95% confidence interval 0.553-0.757; p = 0.004) at baseline and 0.737 (95% confidence interval 0.643-0.827; p < 0.001) at 1 year after initiation of treatment. Change in ISWT distance also predicted survival (p = 0.04). Heart rate (HR) and systolic blood pressure (SBP) parameters reflecting autonomic response to exercise (highest HR, change in HR, HR recovery at 1 minute >18 beats/min, highest SBP, change in SBP, and 3-minute SBP ratio) were significant predictors of survival (all p < 0.05).

CONCLUSIONS

In patients with PAH, the ISWT is simple to perform, allows assessment of maximal exercise capacity, is sensitive to treatment effect, predicts outcome, and has no ceiling effect. Also, measures of autonomic function made post-exercise predict survival in PAH.

Management of pulmonary hypertension due to heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a major cause of HF-related morbidity and mortality, with no medical therapy proven to modify the underlying disease process and result in improvements in survival. With long-standing pulmonary venous congestion, a majority of HFpEF patients develop pulmonary hypertension (PH). Elevated pulmonary pressures have been shown to be a major determinant of mortality in this population. Given the paucity of available disease-modifying therapies for HFpEF, there has been a considerable interest in evaluating new therapeutic options specifically targeting PH in this patient population.

Cardiac hemodynamic response to the 6-minute walk test in young adults and the elderly

BACKGROUND

Exercise capacity is evaluated using the 6-minute walk test in various diseases. Variety in the distances walked was also shown in healthy subjects. Moreover, age-related influences on cardiac hemodynamic response to the 6-minute walk test have not been clarified. The purpose of this study was thus to investigate the hemodynamic response to the 6-minute walk test and to detect factors related to the distance walked in healthy subjects.

METHODS

Thirteen young adults (age 20.5 ± 0.7 years, BMI 22.0 ± 4.3) and 26 elderly individuals (age 60.2 ± 6.1 years, BMI 21.7 ± 2.2) were enrolled to measure real-time hemodynamic responses using non-invasive impedance cardiography during the 6-minute walk test.

RESULTS

Stroke volume was higher in the young than in the elderly and reached a plateau within 30 s of starting to walk in all subjects. An increase in heart rate took more than 1 min in the elderly, while it took less than 30 s in the young, which resulted in slower increases in cardiac output and cardiac index in the elderly. There was no difference in the distance in the 6-minute walk test between the young and the elderly. The distance walked was correlated with heart rate, cardiac output, and cardiac index, but not with stroke volume, at the end of the 6-minute walk test.

CONCLUSIONS

The distance walked appeared to depend on increased cardiac output based on heart rate, but did not appear to be limited by stroke volume, in healthy subjects.