Cardiopulmonary and metabolic responses during a 2-day CPET in myalgic encephalomyelitis/chronic fatigue syndrome: translating reduced oxygen consumption to impairment status to treatment considerations

BACKGROUND

Post-exertional malaise (PEM), the hallmark symptom of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), represents a constellation of abnormal responses to physical, cognitive, and/or emotional exertion including profound fatigue, cognitive dysfunction, and exertion intolerance, among numerous other maladies. Two sequential cardiopulmonary exercise tests (2-d CPET) provide objective evidence of abnormal responses to exertion in ME/CFS but validated only in studies with small sample sizes. Further, translation of results to impairment status and approaches to symptom reduction are lacking.

METHODS

Participants with ME/CFS (Canadian Criteria; n = 84) and sedentary controls (CTL; n = 71) completed two CPETs on a cycle ergometer separated by 24 h. Two-way repeated measures ANOVA compared CPET measures at rest, ventilatory/anaerobic threshold (VAT), and peak effort between phenotypes and CPETs. Intraclass correlations described stability of CPET measures across tests, and relevant objective CPET data indicated impairment status. A subset of case-control pairs (n = 55) matched for aerobic capacity, age, and sex, were also analyzed.

RESULTS

Unlike CTL, ME/CFS failed to reproduce CPET-1 measures during CPET-2 with significant declines at peak exertion in work, exercise time, V ˙ e, V ˙ O2, V ˙ CO2, V ˙ T, HR, O2pulse, DBP, and RPP. Likewise, CPET-2 declines were observed at VAT for V ˙ e/ V ˙ CO2, PetCO2, O2pulse, work, V ˙ O2 and SBP. Perception of effort (RPE) exceeded maximum effort criteria for ME/CFS and CTL on both CPETs. Results were similar in matched pairs. Intraclass correlations revealed greater stability in CPET variables across test days in CTL compared to ME/CFS owing to CPET-2 declines in ME/CFS. Lastly, CPET-2 data signaled more severe impairment status for ME/CFS compared to CPET-1.

CONCLUSIONS

Presently, this is the largest 2-d CPET study of ME/CFS to substantiate impaired recovery in ME/CFS following an exertional stressor. Abnormal post-exertional CPET responses persisted compared to CTL matched for aerobic capacity, indicating that fitness level does not predispose to exertion intolerance in ME/CFS. Moreover, contributions to exertion intolerance in ME/CFS by disrupted cardiac, pulmonary, and metabolic factors implicates autonomic nervous system dysregulation of blood flow and oxygen delivery for energy metabolism. The observable declines in post-exertional energy metabolism translate notably to a worsening of impairment status. Treatment considerations to address tangible reductions in physiological function are proffered.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, retrospectively registered, ID# NCT04026425, date of registration: 2019-07-17.

Determinants of V̇+O2peak Changes After Aerobic Training in Coronary Heart Disease Patients

This study aimed to highlight the ventilatory and circulatory determinants of changes in ˙VO2peak after exercise-based cardiac rehabilitation (ECR) in patients with coronary heart disease (CHD). Eighty-two CHD patients performed, before and after a 3-month ECR, a cardiopulmonary exercise testing (CPET) on a bike with gas exchanges measurements (˙VO2peak, minute ventilation, i. e., ˙VE), and cardiac output (Q˙c). The arteriovenous difference in O2 (C(a-v¯)O2) and the alveolar capillary gradient in O2 (PAi-aO2) were calculated using Fick's laws. Oxygen uptake efficiency slope (OUES) was calculated. A 5.0% cut off was applied for differentiating non- (NR: ˙VO2<0.0%), low (LR: 0.0≤ ∆˙VO2<5.0%), moderate (MR: 5.0≤∆˙VO2 < 10.0%), and high responders (HR: ∆˙VO2≥10.0%) to ECR. A total of 44% of patients were HR (n=36), 20% MR (n=16), 23% LR (n=19), and 13% NR (n=11). For HR, the ˙VO2peak increase (p<0.01) was associated with increases in ˙VE (+12.8±13.0 L/min, p<0.01), (+1.0±0.9 L/min, p<0.01), and C(a-v¯)O2 (+2.3±2.5 mLO2/100 mL, p<0.01). MR patients were characterized by+6.7±19.7 L/min increase in ˙VE (p=0.04) and+0.7±1.0 L/min of Q˙c (p<0.01). ECR induced decreases in ˙VE (p=0.04) and C(a-v¯)O2 (p<0.01) and a Q˙c increase in LR and NR patients (p<0.01). Peripheral and ventilatory responses more than central adaptations could be responsible for the ˙VO2peak change with ECR in CHD patients.

Comparable Ventilatory Inefficiency at Maximal and Submaximal Performance in COPD vs. CHF subjects: An Innovative Approach

BACKGROUND

Currently, excess ventilation has been grounded under the relationship between minute-ventilation/carbon dioxide output ( V ˙ E - V ˙ CO 2 ). Alternatively, a new approach for ventilatory efficiency ( η E V ˙ ) has been published.

OBJECTIVE

Our main hypothesis is that comparatively low levels of η E V ˙ between chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD) are attainable for a similar level of maximum and submaximal aerobic performance, conversely to long-established methods ( V ˙ E - V ˙ CO 2 slope and intercept).

METHODS

Both groups performed lung function tests, echocardiography, and cardiopulmonary exercise testing. The significance level adopted in the statistical analysis was 5%. Thus, nineteen COPD and nineteen CHF-eligible subjects completed the study. With the aim of contrasting full values of V ˙ E - V ˙ CO 2 and η V ˙ E for the exercise period (100%), correlations were made with smaller fractions, such as 90% and 75% of the maximum values.

RESULTS

The two groups attained matched characteristics for age (62±6 vs. 59±9 yrs, p>.05), sex (10/9 vs. 14/5, p>0.05), BMI (26±4 vs. 27±3 Kg m2, p>0.05), and peak V ˙ O 2 (72±19 vs. 74±20 %pred, p>0.05), respectively. The V ˙ E - V ˙ CO 2 slope and intercept were significantly different for COPD and CHF (27.2±1.4 vs. 33.1±5.7 and 5.3±1.9 vs. 1.7±3.6, p<0.05 for both), but η V ˙ E average values were similar between-groups (10.2±3.4 vs. 10.9±2.3%, p=0.462). The correlations between 100% of the exercise period with 90% and 75% of it were stronger for η V ˙ E (r>0.850 for both).

CONCLUSION

The η V ˙ E is a valuable method for comparison between cardiopulmonary diseases, with so far distinct physiopathological mechanisms, including ventilatory constraints in COPD.

Exercise intolerance in heart failure with preserved ejection fraction: Causes, consequences and the journey towards a cure

Heart failure with preserved ejection fraction (HFpEF) accounts for over 50% of all heart failure cases nationwide and continues to rise in its prevalence. The complex, multi-organ involvement of the HFpEF clinical syndrome requires clinicians and investigators to adopt an integrative approach that considers the contribution of both cardiac and non-cardiac function to HFpEF pathophysiology. Thus, this symposium review outlines the key points from presentations covering the contributions of disease-related changes in cardiac function, arterial stiffness, peripheral vascular function, and oxygen delivery and utilization to exercise tolerance in patients with HFpEF. While many aspects of HFpEF pathophysiology remain poorly understood, there is accumulating evidence for a decline in vascular health in this patient group that may be remediable through pharmacological and lifestyle interventions and could improve outcomes and clinical status in this ever-growing patient population.

Trainability for cardiopulmonary fitness is low in patients with peripheral artery disease

AIMS

In patients with peripheral arterial disease (PAD), exercise therapy is recommended to relieve leg symptoms, as noted in the 2016 AHA/ACC and 2017 ESC/ESVS guidelines. We assessed the trainability for cardiopulmonary fitness (CPF) and quality of life (QOL); three distinct patient types, namely, PAD, heart failure (HF), and stroke, were compared.

METHODS AND RESULTS

This is a multicentre, retrospective analysis of prospectively collected data from three clinical studies. Data collected from 123 patients who completed 36 sessions of supervised aerobic training of moderate intensity were analysed, with 28 PAD, 55 HF, and 40 stroke patients totalling 123. Before and after training, cardiopulmonary exercise testing with non-invasive cardiac output monitoring and QOL evaluation using a 36-Item Short Form Survey (SF-36) were performed. Non-response was defined as a negative change in the post-training value compared with that in the pre-training value. The result showed an improvement in CPF in all three groups. However, cardiorespiratory fitness (CRF) increased by a lesser extent in the PAD group than in the HF and stroke groups; the physical and mental component scores (MCS) of SF-36 exhibited a similar pattern. Non-response rates of peak V˙O2, oxygen uptake efficiency slope, and MCS were higher in the PAD group. In the PAD group, non-responders regarding peak V˙O2 had a higher pulse wave velocity than responders.

CONCLUSION

In patients with PAD following exercise therapy, CRF and QOL improved to a lesser extent on average; their non-response rate was also higher compared with that of HF or stroke patients. Therefore, a higher dose of exercise might be needed to elicit adaptation in PAD patients, especially those with high pulse wave velocity.

Quantifying Improvement in V˙ o2peak and Exercise Thresholds in Cardiovascular Disease Using Reliable Change Indices

PURPOSE

Improving aerobic fitness through exercise training is recommended for the treatment of cardiovascular disease (CVD). However, strong justifications for the criteria of assessing improvement in key parameters of aerobic function including estimated lactate threshold (θ LT ), respiratory compensation point (RCP), and peak oxygen uptake (V˙ o2peak ) at the individual level are not established. We applied reliable change index (RCI) statistics to determine minimal meaningful change (MMC RCI ) cutoffs of θ LT , RCP, and V˙ o2peak for individual patients with CVD.

METHODS

Sixty-six stable patients post-cardiac event performed three exhaustive treadmill-based incremental exercise tests (modified Bruce) ∼1 wk apart (T1-T3). Breath-by-breath gas exchange and ventilatory variables were measured by metabolic cart and used to identify θ LT , RCP, and V˙ o2peak . Using test-retest reliability and mean difference scores to estimate error and test practice/exposure, respectively, MMC RCI values were calculated for V˙ o2 (mL·min -1. kg -1 ) at θ LT , RCP, and V˙ o2peak .

RESULTS

There were no significant between-trial differences in V˙ o2 at θ LT ( P = .78), RCP ( P = .08), or V˙ o2peak ( P = .74) and each variable exhibited excellent test-retest variability (intraclass correlation: 0.97, 0.98, and 0.99; coefficient of variation: 6.5, 5.4, and 4.9% for θ LT , RCP, and V˙ o2peak , respectively). Derived from comparing T1-T2, T1-T3, and T2-T3, the MMC RCI for θ LT were 3.91, 3.56, and 2.64 mL·min -1. kg -1 ; 4.01, 2.80, and 2.79 mL·min -1. kg -1 for RCP; and 3.61, 3.83, and 2.81 mL·min -1. kg -1 for V˙ o2peak . For each variable, MMC RCI scores were lowest for T2-T3 comparisons.

CONCLUSION

These MMC RCI scores may be used to establish cutoff criteria for determining meaningful changes for interventions designed to improve aerobic function in individuals with CVD.

Effects of remote coaching following supervised exercise oncology rehabilitation on physical activity levels, physical fitness, and patient-reported outcomes: a randomised controlled trial

BACKGROUND

Studies have shown that cancer survivors experience difficulties maintaining physical activity levels after participation in a supervised exercise rehabilitation program. This study aimed to assess the effectiveness of a six-month remote coaching intervention, following a supervised exercise oncology rehabilitation program on maintenance of PA levels; and improvement of aerobic capacity, muscle strength and patient-reported outcomes in cancer survivors.

METHODS

Ninety-seven participants from a Dutch University Hospital's exercise rehabilitation program were randomised to the COACH group (n = 46), receiving 6 months of remote coaching after completing the exercise program, or the CONTROL group (n = 50), receiving no additional intervention. Assessment of PA levels; sedentary time; aerobic capacity; muscle strength; fatigue; health-related quality of life (HRQoL); level of anxiety and depression; and return to work (RTW) rates were conducted at baseline (T0) and six months later (T1). Multiple linear regression was used for between-group statistical comparisons of all outcomes measures. Mean differences at T1 were estimated with corresponding 95% confidence intervals (95%CI).

RESULTS

No significant between-group differences were observed for all outcomes at T1. An adjusted mean difference in weekly PA of 45 min (95%CI -50;140) was observed between the COACH group and the CONTROL group, favouring the COACH group, yet lacking statistical or clinical significance.

CONCLUSIONS

Our six-month remote coaching intervention did not notably improve PA levels; sedentary time; aerobic capacity; muscle strength; HRQoL; fatigue; anxiety and depression symptoms and RTW rates after participation in a supervised exercise oncology program. Although the participants who received coaching showed slightly higher levels of PA, these differences were not significant. More research is needed to identify patients in need for follow-up interventions following supervised exercise program and to investigate the effectiveness of remote coaching interventions in these patients.

TRIAL REGISTRATION

Dutch Trial Register NL7729, registered 13 may 2019, https://trialsearch.who.int/Trial2.aspx?TrialID=NL7729 .

Aquatic high-intensity interval training (HIIT) may be similarly effective to land-based HIIT in improving exercise capacity in people with chronic conditions: a systematic review and meta-analysis

Objective

To investigate the effect of aquatic high-intensity interval training (AHIIT) on exercise capacity in people with chronic conditions.

Design

Systematic review and meta-analysis.

Participants

Adults (age ≥18 years) with any chronic conditions (long duration, continuing health problems).

Data sources

The databases Medline, EMBASE, CINAHL, SPORTSDiscus, PEDro and The Cochrane Library were searched from inception to 11 August 2023.

Eligibility criteria

Randomised or non-randomised controlled trials of adults reporting one or more chronic conditions were included, comparing the effect of AHIIT with a non-exercising control group, land-based high-intensity interval training (LBHIIT) or aquatic moderate-intensity continuous training (AMICT).

Results

Eighteen trials with 868 participants with chronic musculoskeletal, respiratory, cardiovascular, metabolic or neurological conditions were included. Adherence to AHIIT was high, ranging from 84% to 100%. There was moderate certainty in evidence according to the Grading of Recommendations Assessment, Development and Evaluation system for a moderate beneficial effect on exercise capacity standardised mean differences (SMD) 0.78 (95% CI 0.48 to 1.08), p<0.00001) of AHIIT compared with a non-exercising control group. There was moderate certainty in evidence for no difference of effects on exercise capacity (SMD 0.28 (95% CI -0.04 to 0.60), p=0.08) of AHIIT compared with LBHIIT. There was moderate certainty in evidence for small effect on exercise capacity (SMD 0.45 (95% CI 0.10 to 0.80), p=0.01) of AHIIT compared with AMICT.

Conclusion

There are beneficial effects of AHIIT on exercise capacity in people with a range of chronic conditions. AHIIT has similar effects on exercise capacity as LBHIIT and may represent an alternative for people unable to perform LBHIIT.

PROSPERO registration number

CRD42022289001.

Cardiopulmonary exercise testing criteria for advanced therapies in patients with heart failure

Many cardiology associations endorse the role of the cardiopulmonary exercise test (CPET) to define the severity of impairment of functional capacity in individuals with heart failure with reduced ejection fraction (HFrEF) and when evaluating the need for advanced therapies for these patients. The focus of the CPET within the cardiology community has been on peak volume of oxygen uptake (VO2). However, several CPET variables are associated with outcomes in individuals with and without chronic disease and can inform clinical decisions in individuals with HFrEF. In this manuscript, we will review the normal cardiopulmonary response to a graded exercise test and review current guideline recommendations relative to CPET in patients with HFrEF.

Relationship of maximum walking speed with peak oxygen uptake and anaerobic threshold in male patients with heart failure

This retrospective observational study aimed to examine the relationships of maximum walking speed (MWS) with peak oxygen uptake (peak VO2) and anaerobic threshold (AT) obtained by cardiopulmonary exercise testing (CPX) in patients with heart failure. The study participants were 104 consecutive men aged ≥ 20 years who had been hospitalized or had undergone outpatient care at our hospital for heart failure between February 2019 and January 2023. MWS was measured in a 5-m section with a 1-m run-up before and after the course. Multivariable analysis was used to examine the association between MWS and peak VO2 and AT by CPX. The Pearson correlation coefficient showed that MWS was positively correlated with percent-predicted peak VO2 and percent-predicted AT (r = 0.463, p < 0.001; and r = 0.485, p < 0.001, respectively). In the multiple linear regression analysis employing percent-predicted peak VO2 and percent-predicted AT as the objective variables, only MWS demonstrated a significant positive correlation (standardized β: 0.471, p < 0.001 and 0.362, p < 0.001, respectively). Multiple logistic regression analyses, using an 80% cutoff in percent-predicted peak VO2 and AT, revealed that only MWS was identified as a significant factor in both cases (odds ratio [OR]: 1.239, 95% confidence interval [CI]: 1.071-1.432, p = 0.004 and OR: 1.469, 95% CI: 1.194-1.807, p < 0.001, respectively). MWS was correlated with peak VO2 and AT in male patients with heart failure. The MWS measurement as a screening test for exercise tolerance may provide a simple means of estimating peak VO2 and AT in heart failure patients.

Monitoring aerobic capacity in cancer survivors using self-reported questionnaires: criterion validity and responsiveness

BACKGROUND

Evaluating the criterion validity and responsiveness of the self-reported FitMáx©-questionnaire, Duke Activity Status Index (DASI) and Veterans Specific Activity Questionnaire (VSAQ) to monitor aerobic capacity in cancer survivors.

METHODS

Cancer survivors participating in a 10-week supervised exercise program were included. The FitMáx©-questionnaire, DASI, VSAQ and a cardiopulmonary exercise test (CPET) were completed before (T₀) and after (T₁) the program. Intraclass correlation coefficients (ICC) were calculated between VO_2peak estimated by the questionnaires (questionnaire-VO_2peak) and VO_2peak measured during CPET (CPET-VO_2peak), at T₀ to examine criterion validity, and between changes in questionnaire-VO_2peak and CPET-VO_2peak (ΔT₀-T₁) to determine responsiveness. Receiver operating characteristic (ROC) analyses were performed to examine the ability of the questionnaires to detect true improvements (≥ 6%) in CPET-VO_2peak.

RESULTS

Seventy participants were included. Outcomes at T₁ were available for 58 participants (83%). Mean CPET-VO_2peak significantly improved at T₁ (Δ1.6 mL·kg^- 1·min^- 1 or 8%). Agreement between questionnaire-VO_2peak and CPET-VO_2peak at T₀ was moderate for the FitMáx©-questionnaire (ICC = 0.69) and VSAQ (ICC = 0.53), and poor for DASI (ICC = 0.36). Poor agreement was found between ΔCPET-VO_2peak and Δquestionnaire-VO_2peak for all questionnaires (ICC 0.43, 0.19 and 0.18 for the FitMáx©-questionnaire, VSAQ and DASI, respectively). ROC analysis showed that the FitMáx©-questionnaire was able to detect improvements in CPET-VO_2peak (area under the curve, AUC = 0.77), when using a cut-off value of 1.0 mL·kg^- 1·min^- 1, while VSAQ (AUC = 0.66) and DASI (AUC = 0.64) could not.

CONCLUSION

The self-reported FitMáx©-questionnaire has sufficient validity to estimate aerobic capacity in cancer survivors at group level. The responsiveness of the FitMáx©-questionnaire for absolute change is limited, but the questionnaire is able to detect whether aerobic capacity improved. The FitMáx©-questionnaire showed substantial better values of validity and responsiveness compared to DASI and VSAQ.

Supervised Exercise Training for Chronic Heart Failure With Preserved Ejection Fraction: A Scientific Statement From the American Heart Association and American College of Cardiology

Heart failure with preserved ejection fraction (HFpEF) is one of the most common forms of heart failure; its prevalence is increasing, and outcomes are worsening. Affected patients often experience severe exertional dyspnea and debilitating fatigue, as well as poor quality of life, frequent hospitalizations, and a high mortality rate. Until recently, most pharmacological intervention trials for HFpEF yielded neutral primary outcomes. In contrast, trials of exercise-based interventions have consistently demonstrated large, significant, clinically meaningful improvements in symptoms, objectively determined exercise capacity, and usually quality of life. This success may be attributed, at least in part, to the pleiotropic effects of exercise, which may favorably affect the full range of abnormalities-peripheral vascular, skeletal muscle, and cardiovascular-that contribute to exercise intolerance in HFpEF. Accordingly, this scientific statement critically examines the currently available literature on the effects of exercise-based therapies for chronic stable HFpEF, potential mechanisms for improvement of exercise capacity and symptoms, and how these data compare with exercise therapy for other cardiovascular conditions. Specifically, data reviewed herein demonstrate a comparable or larger magnitude of improvement in exercise capacity from supervised exercise training in patients with chronic HFpEF compared with those with heart failure with reduced ejection fraction, although Medicare reimbursement is available only for the latter group. Finally, critical gaps in implementation of exercise-based therapies for patients with HFpEF, including exercise setting, training modalities, combinations with other strategies such as diet and medications, long-term adherence, incorporation of innovative and more accessible delivery methods, and management of recently hospitalized patients are highlighted to provide guidance for future research.

Clinician approach to cardiopulmonary exercise testing for exercise prescription in patients at risk of and with cardiovascular disease

Exercise training is highly recommended in current guidelines on primary and secondary prevention of cardiovascular disease (CVD). This is based on the cardiovascular benefits of physical activity and structured exercise, ranging from improving the quality of life to reducing CVD and overall mortality. Therefore, exercise should be treated as a powerful medicine and critical component of the management plan for patients at risk for or diagnosed with CVD. A tailored approach based on the patient's personal and clinical characteristics represents a cornerstone for the benefits of exercise prescription. In this regard, the use of cardiopulmonary exercise testing is well-established for risk stratification, quantification of cardiorespiratory fitness and ventilatory thresholds for a tailored, personalised exercise prescription. The aim of this paper is to provide a practical guidance to clinicians on how to use data from cardiopulmonary exercise testing towards personalised exercise prescriptions for patients at risk of or with CVD.

Effects of exercise-based cardiac rehabilitation delivery modes on exercise capacity and health-related quality of life in heart failure: a systematic review and network meta-analysis

Background

This review aimed to compare the relative effectiveness of different exercise-based cardiac rehabilitation (ExCR) delivery modes (centre-based, home-based, hybrid and technology-enabled ExCR) on key heart failure (HF) outcomes: exercise capacity, health-related quality of life (HRQoL), HF-related hospitalisation and HF-related mortality.

Methods and results

Randomised controlled trials (RCTs) published through 20 June 2021 were identified from six databases, and reference lists of included studies. Risk of bias and certainty of evidence were evaluated using the Cochrane tool and Grading of Recommendations Assessment, Development and Evaluation, respectively. Bayesian network meta-analysis was performed using R. Continuous and binary outcomes are reported as mean differences (MD) and ORs, respectively, with 95% credible intervals (95% CrI). One-hundred and thirty-nine RCTs (n=18 670) were included in the analysis. Network meta-analysis demonstrated improvements in VO₂peak following centre-based (MD (95% CrI)=3.10 (2.56 to 3.65) mL/kg/min), home-based (MD=2.69 (1.67 to 3.70) mL/kg/min) and technology-enabled ExCR (MD=1.76 (0.27 to 3.26) mL/kg/min). Similarly, 6 min walk distance was improved following hybrid (MD=84.78 (31.64 to 138.32) m), centre-based (MD=50.35 (30.15 to 70.56) m) and home-based ExCR (MD=36.77 (12.47 to 61.29) m). Incremental shuttle walk distance did not improve following any ExCR delivery modes. Minnesota living with HF questionnaire improved after centre-based (MD=−10.38 (−14.15 to –6.46)) and home-based ExCR (MD=−8.80 (−13.62 to –4.07)). Kansas City Cardiomyopathy Questionnaire was improved following home-based ExCR (MD=20.61 (4.61 to 36.47)), and Short Form Survey 36 mental component after centre-based ExCR (MD=3.64 (0.30 to 6.14)). HF-related hospitalisation and mortality risks reduced only after centre-based ExCR (OR=0.41 (0.17 to 0.76) and OR=0.42 (0.16 to 0.90), respectively). Mean age of study participants was only associated with changes in VO₂peak.

Conclusion

ExCR programmes have broader benefits for people with HF and since different delivery modes were comparably effective for improving exercise capacity and HRQoL, the selection of delivery modes should be tailored to individuals’ preferences.

Developments in Exercise Capacity Assessment in Heart Failure Clinical Trials and the Rationale for the Design of METEORIC-HF

Heart failure with reduced ejection fraction (HFrEF) is a highly morbid condition for which exercise intolerance is a major manifestation. However, methods to assess exercise capacity in HFrEF vary widely in clinical practice and in trials. We describe advances in exercise capacity assessment in HFrEF and a comparative analysis of how various therapies available for HFrEF impact exercise capacity. Current guideline-directed medical therapy has indirect effects on cardiac performance with minimal impact on measured functional capacity. Omecamtiv mecarbil is a novel selective cardiac myosin activator that directly increases cardiac contractility and in a phase 3 cardiovascular outcomes study significantly reduced the primary composite end point of time to first heart failure event or cardiovascular death in patients with HFrEF. The objective of the METEORIC-HF trial (Multicenter Exercise Tolerance Evaluation of Omecamtiv Mecarbil Related to Increased Contractility in Heart Failure) is to assess the effect of omecamtiv mecarbil versus placebo on multiple components of functional capacity in HFrEF. The primary end point is to test the effect of omecamtiv mecarbil compared with placebo on peak oxygen uptake as measured by cardiopulmonary exercise testing after 20 weeks of treatment. METEORIC-HF will provide state-of-the-art assessment of functional capacity by measuring ventilatory efficiency, circulatory power, ventilatory anaerobic threshold, oxygen uptake recovery kinetics, daily activity, and quality-of-life assessment. Thus, the METEORIC-HF trial will evaluate the potential impact of increased myocardial contractility with omecamtiv mecarbil on multiple important measures of functional capacity in ambulatory patients with symptomatic HFrEF. Registration: URL: https://clinicaltrials.gov; Unique identifier: NCT03759392.

Exercise intensity assessment and prescription in cardiovascular rehabilitation and beyond: why and how: a position statement from the Secondary Prevention and Rehabilitation Section of the European Association of Preventive Cardiology

A proper determination of the exercise intensity is important for the rehabilitation of patients with cardiovascular disease (CVD) since it affects the effectiveness and medical safety of exercise training. In 2013, the European Association of Preventive Cardiology (EAPC), together with the American Association of Cardiovascular and Pulmonary Rehabilitation and the Canadian Association of Cardiac Rehabilitation, published a position statement on aerobic exercise intensity assessment and prescription in cardiovascular rehabilitation (CR). Since this publication, many subsequent papers were published concerning the determination of the exercise intensity in CR, in which some controversies were revealed and some of the commonly applied concepts were further refined. Moreover, how to determine the exercise intensity during resistance training was not covered in this position paper. In light of these new findings, an update on how to determine the exercise intensity for patients with CVD is mandatory, both for aerobic and resistance exercises. In this EAPC position paper, it will be explained in detail which objective and subjective methods for CR exercise intensity determination exist for aerobic and resistance training, together with their (dis)advantages and practical applications.

Association of adherence to a 3 month cardiac rehabilitation with long-term clinical outcomes in heart failure patients

Aims

Although comprehensive cardiac rehabilitation (CCR) is recommended for patients with heart failure (HF), participants often show low adherence. The aim of this study was to evaluate the association of CCR completion and response with long‐term clinical outcomes.

Methods and results

We screened 824 HF patients who participated in a 3 month CCR programme and underwent baseline assessment, including cardiopulmonary exercise testing (CPX). After excluding 52 participants who experienced all‐cause death or HF hospitalization within 180 days, long‐term outcomes were compared between those who attended 3 month follow‐up assessment including CPX (completers) and those who did not (non‐completers). We also compared the prognostic value of the changes in peak oxygen uptake (VO₂) vs. quadriceps muscle strength (QMS) during the 3 month CCR programme. Among the 772 study patients, there were no significant differences in baseline characteristics, including left ventricular ejection fraction, B‐type natriuretic peptide levels, and peak VO₂, between the completers (n = 561) and non‐completers (n = 211), except for a higher age (63.2 ± 14.2 vs. 59.4 ± 16.2 years; P = 0.0015) and proportion of females (27% vs. 17%; P = 0.0030) among the completers. During a median follow‐up of 55.4 months, the completers had lower rates of the composite of all‐cause death or HF hospitalization (34.4% vs. 44.6%; P = 0.0015) and all‐cause death (16.9% vs. 24.6%; P = 0.0037) than the non‐completers. After adjustment for prognostic baseline characteristics, including age and sex, CCR completion was associated with 34% and 44% reductions in the composite outcome and all‐cause death, respectively. Among the completers, peak VO₂ and QMS increased significantly (8.9 ± 15.8% and 10.5 ± 17.9%, respectively) over 3 months. Patients who had an increase in peak VO₂ ≥ 6.3% (median value) during the CCR programme had significantly lower rates of the composite outcome (27.0% vs. 33.8%; P = 0.048) and all‐cause mortality (10.0% vs. 17.4%; P = 0.0069) than those who did not. No statistically significant difference was observed in the composite outcome (30.5% vs. 30.4%; P = 0.76) or all‐cause mortality (13.0% vs. 14.4%; P = 0.39) between those with and without an increase in QMS ≥8.3% (median value).

Conclusions

In HF patients who participated in a 3 month CCR programme, its completion was associated with lower risks of subsequent HF hospitalization and death. Within the group of patients who completed the programme, the improvement in exercise capacity, but not in skeletal muscle strength, over the 3‐month period was associated with better outcomes. These findings highlight the importance of the post‐CCR follow‐up assessment, including CPX, to identify a patient's adherence and response to the CCR programme.

Agreement between heart rate at first ventilatory threshold on treadmill and at 6-min walk test in coronary artery disease patients on β-blockers treatment

The purpose of this study was to verify the accuracy of the agreement between heart rate at the first ventilatory threshold (HR_VT1) and heart rate at the end of the 6-min walk test (HR_6MWT) in coronary artery disease (CAD) patients on β-blockers treatment. This was a cross-sectional study with stable CAD patients, which performed a cardiopulmonary exercise test (CPET) on a treadmill and a 6-min walk test (6MWT) on nonconsecutive days. The accuracy of agreement between HR_VT1 and HR_6MWT was evaluated by Bland–Altman analysis and Lin’s concordance correlation coefficient (r_c), mean absolute percentage error (MAPE), and standard error of estimate (SEE). Seventeen stable CAD patients on β-blockers treatment (male, 64.7%; age, 61±10 years) were included in data analysis. The Bland–Altman analysis revealed a negative bias of −0.41±6.4 bpm (95% limits of agreements, −13 to 12.2 bpm) between HR_VT1 and HR_6MWT. There was acceptable agreement between HR_VT1 and HR_6MWT (r_c=0.84; 95% confidence interval, 0.63 to 0.93; study power analysis=0.79). The MAPE of the HR_6MWT was 5.1% and SEE was 6.6 bpm. The ratio HR_VT1/HR_peak and HR_6MWT/HR_peak from CPET were not significantly different (81%±5% vs. 81%±6%, P=0.85); respectively. There was a high correlation between HR_VT1 and HR_6MWT (r=0.85, P<0.0001). Finally, the results of the present study demonstrate that there was an acceptable agreement between HR_VT1 and HR_6MWT in CAD patients on β-blockers treatment and suggest that HR_6MWT may be useful to prescribe and control aerobic exercise intensity in cardiac rehabilitation programs.

Mechanisms of Exercise Capacity Improvement after Cardiac Rehabilitation Following Myocardial Infarction Assessed with Combined Stress Echocardiography and Cardiopulmonary Exercise Testing

Cardiac rehabilitation (CR) is indicated in all patients after acute myocardial infarction (AMI) to improve prognosis and exercise capacity (EC). Previous studies reported that up to a third of patients did not improve their EC after CR (non-responders). Our aim was to assess the cardiac and peripheral mechanisms of EC improvement after CR using combined exercise echocardiography and cardiopulmonary exercise testing (CPET-SE). The responders included patients with an improved EC assessed as a rise in peak oxygen uptake (VO₂) ≥ 1 mL/kg/min. Peripheral oxygen extraction was calculated as arteriovenous oxygen difference (A-VO₂Diff). Out of 41 patients (67% male, mean age 57.5 ± 10 years) after AMI with left ventricular ejection fraction (LVEF) ≥ 40%, 73% improved their EC. In responders, peak VO₂ improved by 27% from 17.9 ± 5.2 mL/kg/min to 22.7 ± 5.1 mL/kg/min, p < 0.001, while non-responders had a non-significant 5% decrease in peak VO₂. In the responder group, the peak exercise heart rate, early diastolic myocardial velocity at peak exercise, LVEF at rest and at peak exercise, and A-VO₂Diff at peak exercise increased, the minute ventilation to carbon dioxide production slope decreased, but the stroke volume and cardiac index were unchanged after CR. Non-responders had no changes in assessed parameters. EC improvement after CR of patients with preserved LVEF after AMI is associated with an increased heart rate response and better peripheral oxygen extraction during exercise.

Safety of maximal cardiopulmonary exercise testing in individuals with sickle cell disease: a systematic review

OBJECTIVE

We evaluated the safety of maximal cardiopulmonary exercise testing (CPET) in individuals with sickle cell disease (SCD). Maximal CPET using gas exchange analysis is the gold standard for measuring cardiopulmonary fitness in the laboratory, yet its safety in the SCD population is unclear.

DESIGN

Systematic review.

DATA SOURCES

Systematic search of Medline (PubMed), EMBASE, Cochrane, ClinicalTrials.gov and professional society websites for all published studies and abstracts through December 2020.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Two reviewers independently extracted data of interest from studies that assessed safety outcomes of maximal CPET in children and adults with SCD. A modified version of the Newcastle-Ottawa Scale was used to assess for risk of bias in studies included.

RESULTS

In total, 24 studies met inclusion/exclusion criteria. Adverse events were reported separately or as part of study results in 36 (3.8%) of 939 participants with SCD undergoing maximal CPET in studies included. Most adverse events were related to transient ischaemic changes on ECG monitoring or oxygen desaturation during testing, which did not result in arrhythmias or other complications. Only 4 (0.43%) of 939 participants experienced pain events due to maximal CPET.

CONCLUSION

Maximal CPET appears to be a safe testing modality in children and adults with SCD and can be used to better understand the physiological basis of reduced exercise capacity and guide exercise prescription in this population. Some studies did not focus on reporting adverse events related to exercise testing or failed to mention safety monitoring, which contributed to risk of bias.

Cardiopulmonary Exercise Testing Following Open Repair for a Proximal Thoracic Aortic Aneurysm or Dissection

PURPOSE

There are limited data on cardiopulmonary exercise testing (CPX) and cardiorespiratory fitness (CRF), following open repair for a proximal thoracic aortic aneurysm or dissection. The aim was to evaluate serious adverse events, abnormal CPX event rate, CRF (peak oxygen uptake, (Equation is included in full-text article.)O2peak), and blood pressure.

METHODS

Patients were retrospectively identified from cardiac rehabilitation participation or prospectively enrolled in a research study and grouped by phenotype: (1) bicuspid aortic valve/thoracic aortic aneurysm, (2) tricuspid aortic valve/thoracic aortic aneurysm, and (3) acute type A aortic dissection.

RESULTS

Patients (n = 128) completed a CPX a median of 2.9 mo (interquartile range: 1.8, 3.5) following repair. No serious adverse events were reported, although 3 abnormal exercise tests (2% event rate) were observed. Eighty-one percent of CPX studies were considered peak effort (defined as respiratory exchange ratio of ≥1.05). Median measured (Equation is included in full-text article.)O2peak was <36% predicted normative values (19.2 mL·kgmin vs 29.3 mLkgmin, P < .0001); the most marked impairment in (Equation is included in full-text article.)O2peak was observed in the acute type A aortic dissection group (<40% normative values), which was significantly different from other groups (P < .05). Peak exercise systolic and diastolic blood pressures were 160 mm Hg (144, 172) and 70 mm Hg (62, 80), with no differences noted between groups.

CONCLUSIONS

We observed no serious adverse events with an abnormal CPX event rate of only 2% 3 mo following repair for a proximal thoracic aortic aneurysm or dissection. (Equation is included in full-text article.)O2peak was reduced among all patient groups, especially the acute type A aortic dissection group, which may be clinically significant, given the well-established prognostic importance of reduced cardiorespiratory fitness.

Criterion Validity and Responsiveness of the Steep Ramp Test to Evaluate Aerobic Capacity in Survivors of Cancer Participating in a Supervised Exercise Rehabilitation Program

OBJECTIVE

To evaluate the criterion validity and responsiveness of the steep ramp test (SRT) compared with the cardiopulmonary exercise test (CPET) in evaluating aerobic capacity in survivors of cancer participating in a rehabilitation program.

DESIGN

A prospective cohort study in which survivors of cancer performed an SRT and CPET before (T=0) and after (T=1) a 10-week exercise rehabilitation program. Peak work rate achieved during the SRT (SRT-WRpeak) was compared with peak oxygen consumption measured during the CPET (CPET-Vo₂peak), which is the criterion standard for aerobic capacity. Correlation coefficients were calculated between SRT-WRpeak and CPET-Vo₂peak at T=0 to examine criterion validity and between changes in SRT-WRpeak and CPET-Vo₂peak from T=0 to T=1 to determine responsiveness. Receiver operating characteristic analysis was performed to examine the ability of the SRT to detect a true improvement (6%) in CPET-Vo₂peak.

SETTING

University medical center.

PARTICIPANTS

Survivors of cancer (N=106).

INTERVENTIONS

Exercise rehabilitation.

MAIN OUTCOME MEASURES

Correlation coefficients between CPET-Vo₂peak and SRT-WRpeak and between changes in CPET-Vo₂peak and SRT-WRpeak.

RESULTS

An r of 0.86 (N=106) was found for the relation between SRT-WRpeak and CPET-Vo₂peak at T=0. An r of 0.51 was observed for the relation between changes in SRT-WRpeak and CPET-Vo₂peak (n=59). Receiver operating characteristic analysis showed an area under the curve of 0.74 for the SRT to detect a true improvement in CPET-Vo₂peak, with an optimal cutoff value of +0.26 W/kg (sensitivity 70.7%, specificity 66.7%).

CONCLUSIONS

Because SRT-WRpeak and CPET-Vo₂peak were strongly correlated, the SRT seems a valid tool to estimate aerobic capacity in survivors of cancer. The responsiveness to measure changes in aerobic capacity appears moderate. Nevertheless, the SRT seems able to detect improvement in aerobic capacity, with a cutoff value of 0.26 W/kg.

Effectiveness of Home-Based Mobile Guided Cardiac Rehabilitation as Alternative Strategy for Nonparticipation in Clinic-Based Cardiac Rehabilitation Among Elderly Patients in Europe: A Randomized Clinical Trial

Importance

Although nonparticipation in cardiac rehabilitation is known to increase cardiovascular mortality and hospital readmissions, more than half of patients with coronary artery disease in Europe are not participating in cardiac rehabilitation.

Objective

To assess whether a 6-month guided mobile cardiac rehabilitation (MCR) program is an effective therapy for elderly patients who decline participation in cardiac rehabilitation.

Design, Setting, and Participants

Patients were enrolled in this parallel multicenter randomized clinical trial from November 11, 2015, to January 3, 2018, and follow-up was completed on January 17, 2019, in a secondary care system with 6 cardiac institutions across 5 European countries. Researchers assessing primary outcome were masked for group assignment. A total of 4236 patients were identified with a recent diagnosis of acute coronary syndrome, coronary revascularization, or surgical or percutaneous treatment for valvular disease, or documented coronary artery disease, of whom 996 declined to start cardiac rehabilitation. Subsequently, 179 patients who met the inclusion and exclusion criteria consented to participate in the European Study on Effectiveness and Sustainability of Current Cardiac Rehabilitation Programmes in the Elderly trial. Data were analyzed from January 21 to October 11, 2019.

Interventions

Six months of home-based cardiac rehabilitation with telemonitoring and coaching based on motivational interviewing was used to stimulate patients to reach exercise goals. Control patients did not receive any form of cardiac rehabilitation throughout the study period.

Main Outcomes and Measures

The primary outcome parameter was peak oxygen uptake (Vo2peak) after 6 months.

Results

Among 179 patients randomized (145 male [81%]; median age, 72 [range, 65-87] years), 159 (89%) were eligible for primary end point analysis. Follow-up at 1 year was completed for 151 patients (84%). Peak oxygen uptake improved in the MCR group (n = 89) at 6 and 12 months (1.6 [95% CI, 0.9-2.4] mL/kg-1/min-1 and 1.2 [95% CI, 0.4-2.0] mL/kg-1/min-1, respectively), whereas there was no improvement in the control group (n = 90) (+0.2 [95% CI, -0.4 to 0.8] mL/kg-1/min-1 and +0.1 [95% CI, -0.5 to 0.7] mL/kg-1/min-1, respectively). Changes in Vo2peak were greater in the MCR vs control groups at 6 months (+1.2 [95% CI, 0.2 to 2.1] mL/kg-1/min-1) and 12 months (+0.9 [95% CI, 0.05 to 1.8] mL/kg-1/min-1). The incidence of adverse events was low and did not differ between the MCR and control groups.

Conclusions and Relevance

These results suggest that a 6-month home-based MCR program for patients 65 years or older with coronary artery disease or a valvular intervention was safe and beneficial in improving Vo2peak when compared with no cardiac rehabilitation.

Trial Registration

trialregister.nl Identifier: NL5168.

Bicycle spiroergometry: comparison of standardized examination protocols for adolescents: is it necessary to define own standard values for each protocol?

Purpose

To compare performance data of adolescents collected with five different bicycle spiroergometry protocols and to assess the necessity for establishing standard values for each protocol.

Methods

One-hundred-twenty adolescents completed two bicycle spiroergometries within 14 days. One of the two tests was performed based on our institutional weight-adapted protocol (P0). The other test was performed based on one out of four exercise protocols widely used for children and adolescents (P1, 2, 3 or 4) with 30 persons each. The two tests were performed in a random order. Routine parameters of cardiopulmonary exercise tests (CPET) such as VO₂peak, maximum power, O₂ pulse, OUES, VE/VCO₂ slope as well as ventilatory and lactate thresholds were investigated. Agreement between protocols was evaluated by Bland–Altman analysis, coefficients of variation (CV) and intra-class correlation coefficients (ICC).

Results

None of the CPET parameters were significantly different between P0 and P1, 2, 3 or 4. For most of the parameters, low biases between P0 and P1–P4 were found and 95% confidence intervalls were narrow. CV and ICC values largely corresponded to well-defined analytical goals (CV < 10% and ICC > 0.9). Only maximal power (Pmax) showed differences in size and drift of the bias depending on the length of the step duration of the protocols.

Conclusion

Comparability between examination protocols has been shown for CPET parameters independent on step duration. Protocol-dependent standard values do not appear to be necessary. Only Pmax is dependent on the step duration, but in most cases, this has no significant influence on the fitness assessment.

Ventilatory inefficiency during graded exercise in COPD: A pragmatic approach

BACKGROUND/OBJECTIVE

The current approach to measuring ventilatory (in)efficiency (V'_E -V'CO₂ slope, nadir and intercept) presents critical drawbacks in the evaluation of COPD subjects, owing mainly to mechanical ventilatory constraints. Thus, we aimed to compare the current approach with a new method we have developed for ventilatory efficiency calculation.

METHODS

The new procedure was based on measuring the amount of CO₂ cleared by the lungs (V'CO₂ , L/min) plotted against a predefined range of increase in minute ventilation (V'_E ) (ten-fold increase based on semilog scale) during incremental exercise to symptom-limited maximum tolerance. This value was compared to a hypothetical predicted maximum CO₂ output at the predicted maximal voluntary ventilation, defining ventilatory efficiency (ηV'_E , %). The results were used to compare 30 subjects with COPD (II-IV Global Initiative for Chronic Obstructive Lung Disease, GOLD) and 10 non-COPD smokers, to establish the best discriminative physiological variable for disease severity through logistic multinomial regression.

RESULTS

The new approach was more sensitive to progressive deterioration of airway obstruction, resulting in worse ηV'_E as lung function worsens throughout the GOLD panel (ηV'_E (%), p < .001), when compared with V'_E -V'CO₂ slope (p = .715) or V'_E -V'CO₂ nadir (p = .070), besides showing the best model based on the logistic regression approach.

CONCLUSION

Although requiring more complex calculations compared to the current procedure, the new approach is highly sensitive to true ventilatory/gas-exchange deterioration, even throughout more severe pulmonary lung function in COPD subjects.

Effectiveness of an education intervention associated with an exercise program in improving disease-related knowledge and health behaviours among diabetes patients

OBJECTIVE

to assess the effectiveness of an education intervention associated with an exercise program in improving knowledge and health behaviours among diabetes patients.

METHODS

Diabetes and prediabetes patients were exposed to an evidence- and theoretically-based comprehensive education intervention over 24 weeks. Patients completed surveys assessing knowledge, physical activity, food intake, self-efficacy, and health literacy. Functional capacity was measured by oxygen uptake. All outcomes were assessed pre- and post-CR. Satisfaction about the education provided was assessed at post-CR. Paired t-tests, Pearson correlation coefficients, and linear regression models were computed to investigate the effectiveness of this intervention.

RESULTS

84 patients consented to participate, of which 47(56.0%) completed post-CR assessments. There was a significant improvement in patients' overall knowledge pre- to post-CR, as well as in physical activity, food intake, self-efficacy, and health literacy (p < 0.05). Peak VO₂ has clinically significant improved. Results showed a low significant positive correlation was between post-CR knowledge and food intake(r = 0.297;p = 0.04). Linear regression analysis revealed that age(B=-0.051; p = 0.01) was influential in changing post-CR knowledge.

CONCLUSION

The benefits of an education intervention designed for diabetes and prediabetes patients associated with an exercise program have been supported.

PRACTICE IMPLICATIONS

This work shows one effective education strategy taken in place that can be replicated in different settings.

Exercise Capacity and Ventricular Remodeling After Transcatheter Ventricular Septal Defect Closure in Asymptomatic or Minimally Symptomatic Adolescents and Adults

BACKGROUND

Transcatheter ventricular septal defect (VSD) closure is a safe and efficacious alternative to surgery. However, its benefits in asymptomatic or minimally symptomatic patients remain unknown.

METHODS

Sixty patients with VSD aged 12 to 60 years underwent cardiopulmonary exercise test and echocardiography 1 day before transcatheter VSD closure and 6 months after intervention (closure group). Thirty patients who did not receive the intervention underwent the same evaluations over 6 months (observation group).

RESULTS

No significant change in exercise function was observed after VSD closure, except for increased peak oxygen (O₂) pulse (absolute increase: 0.4±1.4 mL/beat). Left ventricular end-diastolic dimension and mitral peak early filling velocity-to-early diastolic annular velocity ratio decreased (absolute decrease: 0.3±0.6 cm and 0.7±1.9, respectively). Despite unchanged overall peak O₂ consumption, 33% of closure group patients exhibited clinically significant improvements in peak O₂ consumption (>10% increase relative to baseline). This was not related to the pulmonary flow-to-systemic flow ratio or baseline exercise capacity. By contrast, all exercise function parameters deteriorated significantly in the observation group. Subgroup analysis revealed that patients with a baseline left ventricular end-diastolic dimension Z score of >2 exhibited a significantly greater improvement in peak O₂ consumption, peak O₂ pulse, and oxygen uptake efficiency slope than did the observation group.

CONCLUSIONS

Compared with conservative management, transcatheter VSD closure prevents deterioration in exercise capacity and promotes left ventricular reverse remodeling in asymptomatic or minimally symptomatic patients. These benefits are most prominent in patients whose left ventricular end-diastolic dimension Z score before intervention is >2, irrespective of baseline peak O₂ consumption and pulmonary flow/systemic flow ratio. Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT03127748.

Does the combination of photobiomodulation therapy (PBMT) and static magnetic fields (sMF) potentiate the effects of aerobic endurance training and decrease the loss of performance during detraining? A randomised, triple-blinded, placebo-controlled trial

Background

Photobiomodulation (PBMT) is a therapy that uses non-ionising forms of light, including low-level lasers and light-emitting diodes (LEDs) that may be capable of modulating cellular activity. Some biological processes may also interact with static magnetic fields (sMF), leading to modulatory effects on cells. Previous studies have verified that the combination of PBMT and sMF (PBMT/sMF) enhances the performance of individuals during aerobic training programs. The detraining period can cause losses in aerobic capacity. However, there is no evidence of the existence of any recourse that can decrease the effects of detraining. We aimed to investigate the effects of PBMT/sMF application during training and detraining to assess the effectiveness of this treatment in reducing the effects of detraining.

Methods

Sixty male volunteers were randomly allocated into four groups— participants who received PBMT/sMF during the training and detraining (PBMT/sMF + PBMT/sMF); participants who received PBMT/sMF during the training and a placebo in the detraining (PBMT/sMF + Placebo); participants who received a placebo during the training and PBMT/sMF in the detraining (Placebo+PBMT/sMF); and participants who received a placebo during the training and detraining (Placebo+Placebo). Participants performed treadmill training over 12 weeks (3 sessions/week), followed by 4 weeks of detraining. PBMT/sMF was applied using a 12-diode emitter (four 905 nm super-pulsed lasers, four 875 nm light-emitting diodes (LEDs), four 640 nm LEDs, and a 35 mT magnetic field) at 17 sites on each lower limb (dosage: 30 J per site). The data were analysed by two-way repeated measures analysis of variance (ANOVA, time vs experimental group) with post-hoc Bonferroni correction.

Results

The percentage of change in time until exhaustion and in maximum oxygen consumption was higher in the PBMT/sMF + PBMT/sMF group than in the Placebo+Placebo group at all time-points (p < 0.05). Moreover, the percentage of decrease in body fat at the 16th week was higher in the PBMT/sMF + PBMT/sMF group than in the Placebo+Placebo group (p < 0.05).

Conclusions

PBMT/sMF can potentiate the effects of aerobic endurance training and decrease performance loss after a 4-week detraining period. Thus, it may prove to be an important tool for both amateur and high-performance athletes as well as people undergoing rehabilitation.

Trial registration

NCT03879226. Trial registered on 18 March 2019.

Effects of photobiomodulation therapy in aerobic endurance training and detraining in humans: Protocol for a randomized placebo-controlled trial

INTRODUCTION

Over the last 10 years, it has been demonstrated that photobiomodulation therapy (PBMT), also known as phototherapy, using low-level laser therapy (LLLT) and/or light-emitting diode therapy (LEDT) has ergogenic effects, improving athletic performance and also accelerating post-exercise recovery. However, many aspects related to these effects and its clinical applicability remain unknown. Therefore, the aim of this project is to evaluate the ergogenic effects of PBMT in detraining after an aerobic endurance training protocol.

METHODS AND ANALYZES

A randomized, triple-blind, placebo-controlled clinical trial will be carried out. Healthy male volunteers will be randomly distributed into 4 experimental groups: PBMT before and after training sessions + PBMT during detraining, PBMT before and after training sessions + placebo during detraining, placebo before and after training sessions + PBMT during detraining, and placebo before and after training sessions + placebo during detraining. The aerobic endurance training sessions will be carried out using motorized treadmills during 12 weeks, and the detraining period will consist in the next 4 weeks after that. It will be analyzed the time until exhaustion, maximal oxygen uptake (VO2max), and fat percentage of volunteers.

DISCUSSION

Despite the increasing body of evidence for the use of PBMT as an ergogenic agent, several aspects remain unknown. The findings of this study will contribute to the advance of knowledge in this field regarding clinical applications.

ETHICS AND DISSEMINATION

This study was approved by the Research Ethics Committee of Nove de Julho University. The results from this study will be further disseminated through scientific publications in international peer-reviewed journals and presentations at national and international scientific meetings.

TRIAL REGISTRATION NUMBER

NCT03879226.

Repeatability and Meaningful Change of CPET Parameters in Healthy Subjects

INTRODUCTION/PURPOSE

Cardiopulmonary exercise testing (CPET) plays an important role in clinical medicine and research. Repeatability of CPET parameters has not been well characterized, but is important to assess variability and determine if there have been meaningful changes in a given CPET parameter.

METHODS

We recruited 45 healthy subjects and performed two symptom-limited CPET within 30 d using a cycle ergometer. Differences in relevant CPET parameters between CPET-1 and CPET-2 were assessed using a paired t-test. Coefficient of variation (CoV) and Bland-Altman plots are reported. Factors that may be associated with variability were analyzed (sex, age, time of day, fitness level). The coefficient of repeatability was calculated for peak oxygen consumption (V˙O2) and V˙O2 at lactate threshold (LT) to establish a 95% threshold for meaningful change.

RESULTS

There were no significant differences between tests in the parameters reported. Specifically, we found overall low CoV in peak V˙O2 (4.9%), V˙O2@LT (10.4%), peak O2 pulse (4.6%), peak minute ventilation (V˙E; 7.4%), V˙E/V˙CO2@LT (4.0%), and V˙E/V˙O2@LT (4.8%). The CoV for peak respiratory exchange ratio@LT was significantly affected by diurnal factors; age, sex, and fitness level did not affect variability. The 95% threshold for meaningful change was 0.540 L·min in peak V˙O2 and 0.520 L·min in V˙O2@LT.

CONCLUSIONS

Repeatability of CPET parameters is generally higher than previously reported. There were no significant differences in variability related to sex, age, and fitness level; diurnal factors had a limited effect. The threshold for meaningful change in peak V˙O2 and for V˙O2@LT should be considered when gauging a response to therapies or training.

Absence of Fitness Improvement Is Associated with Outcomes in Heart Failure Patients

PURPOSE

This study aimed to examine the clinical effect of cardiorespiratory fitness (CRF) and improvements in CRF after cardiac rehabilitation (CR) in heart failure (HF) patients for their risk for all-cause mortality and unplanned hospitalization and to investigate possible factors associated with the absence of improvement in CRF after rehabilitation.

METHODS

We included 155 HF patients receiving CR between October 2009 and January 2015. Patients performed an incremental bicycle test to assess CRF through peak oxygen uptake (V˙O2-peak) before and after CR-based supervised exercise training. Patients were classified as responders or nonresponders on the basis of pre-to-post CR changes in V˙O2-peak (≥6% and <6%, respectively). Cox proportional hazards models evaluated all-cause mortality and unplanned hospitalization during 5 yr of follow-up. Patient characteristics, HF features, and comorbidities were used to predict changes in V˙O2-peak using logistic regression analysis.

RESULTS

Seventy HF patients (45%) were classified as responder. Nonresponders had a significantly higher risk for all-cause mortality or hospitalization (hazard ratio, 2.15; 95% confidence interval (CI), 1.17-3.94) compared with responders. This was even higher in nonresponders with low CRF at baseline (hazard ratio, 4.88; 95% CI, 1.71-13.93). Factors associated with nonresponse to CR were age (odds ratio (OR), 1.07/yr; 95% CI, 1.03-1.11), baseline V˙O2-peak (OR, 1.16 mL·min·kg; 95% CI, 1.06-1.26), and adherence to CR (OR, 0.98/percentage; 95% CI, 0.96-0.998).

CONCLUSIONS

Independent from baseline CRF, the inability to improve V˙O2-peak by CR doubled the risk for death or unplanned hospitalization. The combination of lower baseline CRF and nonresponse was associated with even poorer clinical outcomes. Especially older HF patients with higher baseline V˙O2-peak and lower adherence have a higher probability of becoming a nonresponder.

The cardiopulmonary exercise test grey zone; optimising fitness stratification by application of critical difference

BACKGROUND

Cardiorespiratory fitness can inform patient care, although to what extent natural variation in CRF influences clinical practice remains to be established. We calculated natural variation for cardiopulmonary exercise test (CPET) metrics, which may have implications for fitness stratification.

METHODS

In a two-armed experiment, critical difference comprising analytical imprecision and biological variation was calculated for cardiorespiratory fitness and thus defined the magnitude of change required to claim a clinically meaningful change. This metric was retrospectively applied to 213 patients scheduled for colorectal surgery. These patients underwent CPET and the potential for misclassification of fitness was calculated. We created a model with boundaries inclusive of natural variation [critical difference applied to oxygen uptake at anaerobic threshold (V˙O2-AT): 11 ml O2 kg-1 min-1, peak oxygen uptake (V˙O2 peak): 16 ml O2 kg-1 min-1, and ventilatory equivalent for carbon dioxide at AT (V̇E/V̇CO2-AT): 36].

RESULTS

The critical difference for V˙O2-AT, V˙O2 peak, and V˙E/V˙CO2-AT was 19%, 13%, and 10%, respectively, resulting in false negative and false positive rates of up to 28% and 32% for unfit patients. Our model identified boundaries for unfit and fit patients: AT <9.2 and ≥13.6 ml O2 kg-1 min-1, V˙O2 peak <14.2 and ≥18.3 ml kg-1 min-1, V˙E/V˙CO2-AT ≥40.1 and <32.7, between which an area of indeterminate-fitness was established. With natural variation considered, up to 60% of patients presented with indeterminate-fitness.

CONCLUSIONS

These findings support a reappraisal of current clinical interpretation of cardiorespiratory fitness highlighting the potential for incorrect fitness stratification when natural variation is not accounted for.

Test-Retest Reliability of Maximal and Submaximal Gas Exchange Variables in Patients With Coronary Artery Disease

PURPOSE

Gas exchange variables derived from cardiopulmonary exercise tests (CPETs) need to be reliable for evaluating interventions and clinical decision making. Whereas peak oxygen uptake ((Equation is included in full-text article.)O2) has shown to be a highly reliable parameter in patients with coronary artery disease (CAD), little is known about the reproducibility of these parameters in patients with CAD. Therefore, the purpose of this study was to confirm the reliability of peak (Equation is included in full-text article.)O2 and to investigate the reliability of submaximal CPET variables in patients with CAD.

METHODS

Eighty-five patients with CAD (57.6 ± 8.5 years; 79 males) performed 2 CPETs within 10 days before starting a rehabilitation program. Reliability of peak and submaximal exercise variables was assessed by using intraclass correlation coefficients (ICC), coefficients of variation, Pearson correlation coefficients, paired t tests, and Bland-Altman plots.

RESULTS

Maximal and submaximal exercise parameters showed adequate reliability. Overall, there was a good correlation across both testing occasions (r = 0.63-0.95; P < .05 for all). Peak (Equation is included in full-text article.)O2 (ICC, 0.95; 95% CI, 0.92-0.97) demonstrated excellent reliability. Of the submaximal exercise variables, oxygen uptake efficiency slope (OUES) was as reliable as peak (Equation is included in full-text article.)O2 (ICC, 0.97; 95% CI, 0.95-0.98). The ventilation/carbon dioxide production ((Equation is included in full-text article.)E/(Equation is included in full-text article.)CO2) slope showed very good test-retest reliability (ICC, 0.87; 95% CI, 0.80-0.91) and the (Equation is included in full-text article.)O2/work rate slope showed good reliability (ICC, 0.76; 95% CI, 0.64-0.85).

CONCLUSIONS

Both peak (Equation is included in full-text article.)O2 and OUES show excellent test-retest reliability. Accordingly, in the case of no or unreliable peak (Equation is included in full-text article.)O2 data, we suggest using OUES to evaluate cardiorespiratory fitness in patients with CAD.

Arm Cycling Combined with Passive Leg Cycling Enhances VO2peak in Persons with Spinal Cord Injury Above the Sixth Thoracic Vertebra

Objective: To test whether passive leg cycling (PLC) during arm cycling ergometry (ACE) affects peak oxygen uptake (VO2peak) differently in individuals with spinal cord injury (SCI) at/above the 6th thoracic vertebra (T6) and below T6. Methods: We conducted a cross-sectional study, analyzed by univariate and multivariate regression models. Between- and within-group differences were examined during (a) ACE only, (b) ACE combined with PLC (ACE-PLC), and (c) ACE combined with functional electrical stimulation cycling (FES hybrid). Fifteen SCI subjects were recruited and grouped according to injury level: at/above T6 (SCI-high, n = 8) or below T6 (SCI-low, n = 7). VO2peak tests during ACE only, ACE-PLC, and FES hybrid were performed in random order on separate days. Results: In the SCI-high group, mean (SD) VO2peak was 19% higher during ACE-PLC than during ACE only [21.0 (3.8) vs 17.7 (5.0) mL·kg-1·min-1; p = .002], while VO2peak during FES hybrid cycling was 16% higher than during ACE-PLC [24.4 (4.1) mL·kg-1·min-1; p = .001]. No significant differences among exercise modalities were found for the SCI-low group. Conclusion: Additional training modalities (eg, PLC) during ACE facilitate exercise in SCI-high individuals, but not to the level of the FES hybrid method. Conversely, additional training modalities may not increase training load in SCI-low individuals.

Role of cardiopulmonary exercise testing in clinical stratification in heart failure. A position paper from the Committee on Exercise Physiology and Training of the Heart Failure Association of the European Society of Cardiology

Traditionally, the main indication for cardiopulmonary exercise testing (CPET) in heart failure (HF) was for the selection of candidates to heart transplantation: CPET was mainly performed in middle-aged male patients with HF and reduced left ventricular ejection fraction. Today, CPET is used in broader patients' populations, including women, elderly, patients with co-morbidities, those with preserved ejection fraction, or left ventricular assistance device recipients, i.e. individuals with different responses to incremental exercise and markedly different prognosis. Moreover, the diagnostic and prognostic utility of symptom-limited CPET parameters derived from submaximal tests is more and more considered, since many patients are unable to achieve maximal aerobic power. Repeated tests are also being used for risk stratification and evaluation of intervention, so that these data are now available. Finally, patients, physicians and healthcare decision makers are increasingly considering how treatments might impact morbidity and quality of life rather than focusing more exclusively on hard endpoints (such as mortality) as was often the case in the past. Innovative prognostic flowcharts, with CPET at their core, that help optimize risk stratification and the selection of management options in HF patients, have been developed.

Prioritizing Functional Capacity as a Principal End Point for Therapies Oriented to Older Adults With Cardiovascular Disease: A Scientific Statement for Healthcare Professionals From the American Heart Association

Adults are living longer, and cardiovascular disease is endemic in the growing population of older adults who are surviving into old age. Functional capacity is a key metric in this population, both for the perspective it provides on aggregate health and as a vital goal of care. Whereas cardiorespiratory function has long been applied by cardiologists as a measure of function that depended primarily on cardiac physiology, multiple other factors also contribute, usually with increasing bearing as age advances. Comorbidity, inflammation, mitochondrial metabolism, cognition, balance, and sleep are among the constellation of factors that bear on cardiorespiratory function and that become intricately entwined with cardiovascular health in old age. This statement reviews the essential physiology underlying functional capacity on systemic, organ, and cellular levels, as well as critical clinical skills to measure multiple realms of function (eg, aerobic, strength, balance, and even cognition) that are particularly relevant for older patients. Clinical therapeutic perspectives and patient perspectives are enumerated to clarify challenges and opportunities across the caregiving spectrum, including patients who are hospitalized, those managed in routine office settings, and those in skilled nursing facilities. Overall, this scientific statement provides practical recommendations and vital conceptual insights.

Observed change in peak oxygen consumption after aortic valve replacement and its predictors

Objective

To assess the change in peak oxygen consumption (pVO₂) and determine its outcome predictors after aortic valve replacement (AVR) for aortic stenosis (AS).

Methods

Patients with AS and preserved left ventricular ejection fraction who were referred for single AVR had cardiopulmonary exercise testing prior to and 9 months post-AVR. Predictors of outcome for pVO₂ were determined by multivariate linear and logistic regression analyses. A significant change in pVO₂ was defined as a relative change that was more than twice the coefficient of repeatability by test–retest (>10%).

Results

The pre-AVR characteristics of the 37 study patients included the following: median age (range) 72 (46–83) years, aortic valve area index (AVAI) 0.41 (SD 0.11) cm²/m², mean gradient (MG) 49.1 (SD 15.3) mm Hg and New York Heart Association (NYHA)≥II 27 (73%). Pre-AVR and post-AVR mean pVO₂ was 18.5 and 18.4 mL/kg/m² (87% of the predicted), respectively, but the change from pre-AVR was heterogeneous. The relative change in pVO₂ was positively associated with the preoperative MG (β=0.50, p=0.001) and negatively associated with brain natriuretic peptide > upper level of normal according to age and gender (β=−0.40, p=0.009). A relative increase in pVO₂ exceeding 10% was found in 9 (24%), predicted by lower pre-AVR AVAI (OR 0.18; 95% CI 0.04 to 0.82, p=0.027) and lower peak O₂ pulse (OR 0.94; 95% CI 0.88 to 0.99, p=0.045). Decreases in pVO₂ exceeding 10% were found in 11 (30%) and predicted by lower MG (OR 0.93; 95% CI 0.86 to 0.99, p=0.033).

Conclusions

Change in pVO₂ was heterogeneous. Predictors of favourable and unfavourable outcomes for pVO₂ were identified.

Use of exercise testing in the evaluation of interventional efficacy: an official ERS statement

This document reviews 1) the measurement properties of commonly used exercise tests in patients with chronic respiratory diseases and 2) published studies on their utilty and/or evaluation obtained from MEDLINE and Cochrane Library searches between 1990 and March 2015.

Exercise tests are reliable and consistently responsive to rehabilitative and pharmacological interventions. Thresholds for clinically important changes in performance are available for several tests. In pulmonary arterial hypertension, the 6-min walk test (6MWT), peak oxygen uptake and ventilation/carbon dioxide output indices appear to be the variables most responsive to vasodilators. While bronchodilators do not always show clinically relevant effects in chronic obstructive pulmonary disease, high-intensity constant work-rate (endurance) tests (CWRET) are considerably more responsive than incremental exercise tests and 6MWTs. High-intensity CWRETs need to be standardised to reduce interindividual variability. Additional physiological information and responsiveness can be obtained from isotime measurements, particularly of inspiratory capacity and dyspnoea. Less evidence is available for the endurance shuttle walk test. Although the incremental shuttle walk test and 6MWT are reliable and less expensive than cardiopulmonary exercise testing, two repetitions are needed at baseline. All exercise tests are safe when recommended precautions are followed, with evidence suggesting that no test is safer than others.

Response to Exercise Training and Outcomes in Patients With Heart Failure and Diabetes Mellitus: Insights From the HF-ACTION Trial

BACKGROUND

In HF-ACTION (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training), exercise training improved functional capacity in heart failure with reduced ejection fraction (HFrEF). Previous studies have suggested that diabetes mellitus (DM) may be associated with an attenuated response to exercise. We explored whether DM attenuated the improvement in functional capacity with exercise.

METHODS AND RESULTS

HF-ACTION randomized 2331 patients with HFrEF to medical therapy with or without exercise training over a median follow-up of 2.5 years. We examined the interaction between DM and exercise response measured by change in 6-minute walk distance (6MWD) and peak VO2. We also examined outcomes by DM status. In HF-ACTION, 748 (32%) patients had DM. DM patients had lower functional capacity at baseline and had lower exercise volumes at 3 months. There was a significant interaction between DM status and exercise training for change in peak VO2 (interaction P = .02), but not 6MWD. In the exercise arm, DM patients had a smaller mean increase in peak VO2 than non-DM patients (P = .03). There was no interaction between DM and exercise on clinical outcomes. After risk adjustment, DM was associated with increased all-cause mortality/hospitalization (P = .03).

CONCLUSIONS

In HF-ACTION, DM was associated with lower baseline functional capacity, an attenuated improvement in peak VO2, and increased hospitalizations.

Cardiopulmonary Exercise Testing in Patients with Asymptomatic or Equivocal Symptomatic Aortic Stenosis: Feasibility, Reproducibility, Safety and Information Obtained on Exercise Physiology

OBJECTIVE

The aim of this study was to determine the feasibility, reproducibility, safety and information obtained on exercise physiology from cardiopulmonary exercise testing (CPX) in patients with aortic stenosis.

METHODS

Patients with an aortic valve area (AVA) <1.3 cm2 who were judged asymptomatic or equivocal symptomatic underwent CPX and an inert gas rebreathing test. Only those where comprehensive evaluation of CPX results indicated haemodynamic compromise from aortic stenosis were referred for valve replacement.

RESULTS

The mean patient age was 72 (±9) years; an AVA index <0.6 cm2/m2 and equivocal symptomatic status were found in 90 and 70%, respectively. CPX was feasible in 130 of the 131 patients. The coefficients of repeatability by test-retest were 5.4% (pVO2) and 4.6% (peak O2 pulse). A pVO2 <83% of the expected was predicted by a lower stroke volume at exercise, lower peak heart rate and FEV1, and higher VE/VCO2, but not by AVA index. Equivocal symptomatic status and a low gradient but high valvulo-arterial impedance were associated with a lower pVO2, but not with an inability to increase stroke volume. In total, 18 patients were referred for valve replacement. At 1 year, no cardiovascular deaths had occurred.

CONCLUSIONS

CPX was feasible and reproducible and provided comprehensive data on exercise physiology. A CPX-guided treatment strategy was safe up to 1 year.

Guidelines for the evaluation and treatment of muscle dysfunction in patients with chronic obstructive pulmonary disease

In patients with chronic obstructive pulmonary disease (COPD), skeletal muscle dysfunction is a major comorbidity that negatively impacts their exercise capacity and quality of life. In the current guidelines, the most recent literature on the various aspects of COPD muscle dysfunction has been included. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) scale has been used to make evidence-based recommendations on the different features. Compared to a control population, one third of COPD patients exhibited a 25% decline in quadriceps muscle strength, even at early stages of their disease. Although both respiratory and limb muscles are altered, the latter are usually more severely affected. Numerous factors and biological mechanisms are involved in the etiology of COPD muscle dysfunction. Several tests are proposed in order to diagnose and evaluate the degree of muscle dysfunction of both respiratory and limb muscles (peripheral), as well as to identify the patients' exercise capacity (six-minute walking test and cycloergometry). Currently available therapeutic strategies including the different training modalities and pharmacological and nutritional support are also described.

Physical activity in patients with heart failure: barriers and motivations with special focus on sex differences

BACKGROUND

Adherence to recommendations for physical activity is low in both male and female patients with heart failure (HF). Men are more physically active than women. In order to successfully promote physical activity, it is therefore essential to explore how much and why HF patients are physically active and if this is related to sex. The aim of this study was therefore to evaluate physical activity in HF patients, to describe the factors related to physical activity, and to examine potential barriers and motivations to physical activity with special focus on sex differences.

METHODS

The study had a cross-sectional survey design. HF patients living at home received a questionnaire during May-July 2014, with questions on physical activity (from the Short Form-International Physical Activity Questionnaire), and potential barriers and motivations to physical activity.

RESULTS

A total of 154 HF patients, 27% women, with a mean age of 70±10 were included. In total, 23% of the patients reported a high level of physical activity, 46% a moderate level, and 34% a low level. Higher education, self-efficacy, and motivation were significantly associated with a higher amount of physical activity. Symptoms or severity of the disease were not related to physical activity. All the potential barriers to exercise were reported to be of importance. Psychological motivations were most frequently rated as being the most important motivation (41%) to be physically active. Physical motivations (33%) and social motivations were rated as the least important ones (22%). Women had significantly higher total motivation to be physically active. These differences were found in social, physical, and psychological motivations.

DISCUSSION

One-third of the HF patients had a low level of physical activity in their daily life. Severity of the disease or symptoms were not related, whereas level of education, exercise self-efficacy, and motivation were important factors to take into account when advising a HF patient about physical activity. Women reported higher motivation to be physically active than men, but there was no difference in the reported level of physical activity.

Greater improvement in cardiorespiratory fitness using higher-intensity interval training in the standard cardiac rehabilitation setting

PURPOSE

We tested the hypothesis that higher-intensity interval training (HIIT) could be deployed into a standard cardiac rehabilitation (CR) setting and would result in a greater increase in cardiorespiratory fitness (ie, peak oxygen uptake, (·)VO₂) versus moderate-intensity continuous training (MCT).

METHODS

Thirty-nine patients participating in a standard phase 2 CR program were randomized to HIIT or MCT; 15 patients and 13 patients in the HIIT and MCT groups, respectively, completed CR and baseline and followup cardiopulmonary exercise testing.

RESULTS

No patients in either study group experienced an event that required hospitalization during or within 3 hours after exercise. The changes in resting heart rate and blood pressure at followup testing were similar for both HIIT and MCT. (·)VO₂ at ventilatory-derived anaerobic threshold increased more (P < .05) with HIIT (3.0 ± 2.8 mL·kg⁻¹·min⁻¹) versus MCT (0.7 ± 2.2 mL·kg⁻¹·min⁻¹). During followup testing, submaximal heart rate at the end of stage 2 of the exercise test was significantly lower within both the HIIT and MCT groups, with no difference noted between groups. Peak (·)VO₂ improved more after CR in patients in HIIT versus MCT (3.6 ± 3.1 mL·kg⁻¹·min⁻¹ vs 1.7 ± 1.7 mL·kg⁻¹·min⁻¹; P < .05).

CONCLUSIONS

Among patients with stable coronary heart disease on evidence-based therapy, HIIT was successfully integrated into a standard CR setting and, when compared to MCT, resulted in greater improvement in peak exercise capacity and submaximal endurance.

Effects of respiratory exchange ratio on the prognostic value of peak oxygen consumption and ventilatory efficiency in patients with systolic heart failure

OBJECTIVES

The purpose of this analysis was to evaluate the prognostic characteristics of peak oxygen consumption (Vo2) and the minute ventilation/carbon dioxide (VE/Vco2) slope of different peak respiratory exchange ratios (RERs) obtained from cardiopulmonary exercise testing in patients with heart failure (HF).

BACKGROUND

For patients with HF, peak Vo2 and the VE/Vco2 slope are used for assessing prognosis. Peak Vo2 is assessed in association with peak RER ≥1.10, indicating maximal effort and prognostic sensitivity. Conversely, the VE/Vco2 slope provides effort-independent prognostic discrimination.

METHODS

Patients with HF scheduled to undergo cardiopulmonary exercise testing were enrolled. Patients were subclassified by peak RER (RER <1.00, RER 1.00 to 1.04, RER 1.05 to 1.09, RER ≥1.10) and followed for up to 3 years for major cardiac-related events (death, left ventricular assist device implantation, or cardiac transplantation).

RESULTS

Included were 1,728 patients with HF (75% males; 40% ischemic etiology; age: 55 ± 14 years; left ventricular ejection fraction: 28 ± 10%). Two hundred seventy major events occurred, with no proportional differences across the RER subgroups. Multivariate Cox regression analysis indicated that the VE/Vco2 slope and peak Vo2 remained prognostic within each subgroup; the VE/Vco2 slope remained the strongest predictor. Receiver-operating characteristic analysis demonstrated equitable prognostic cutoffs for the VE/Vco2 slope (range: 34.9 to 35.7; area under the curve [AUC] range: 0.69 to 0.75) and peak Vo2 (range: 13.8 to 14.0 ml·kg(-1)·min(-1); AUC range: 0.68 to 0.75).

CONCLUSIONS

Peak Vo2 provided a sensitive assessment of prognosis in patients with HF in all RER subgroups. The VE/Vco2 slope provided greater prognostic discrimination in all RER subgroups. Clinical consideration may be warranted for patients with low RER, low peak Vo2, and an elevated VE/Vco2 slope.