Oxygen uptake efficiency slope: an index of exercise performance and cardiopulmonary reserve requiring only submaximal exercise

Association of Sarcopenia and Oxygen Uptake Efficiency Slope in Male Patients With Heart Failure

PURPOSE

Sarcopenia, the loss of muscle mass and function, is a common comorbidity in patients with heart failure (HF). The skeletal muscle modulates the respiratory response during exercise. However, whether ventilatory behavior is affected by sarcopenia is still unknown.

METHODS

We enrolled 169 male patients with HF. Muscle strength was measured by a handgrip dynamometer. Body composition was measured with dual-energy X-ray absorptiometry. Sarcopenia was defined by handgrip strength <27 kg and appendicular lean mass divided by height squared (ALM/height2) <7.0 kg/m2. Oxygen uptake efficiency slope (OUES), ventilation (VE), oxygen uptake (VO2), and carbon dioxide output (VCO2) were measured by a cardiopulmonary exercise test.

RESULTS

Sarcopenia was identified in 29 patients (17%). At the first ventilatory threshold, VE/VO2 (36.9 ± 5.9 vs 32.7 ± 6.5; P = .003) and VE/VCO2 (39.8 ± 7.2 vs 35.3 ± 6.9; P = .004) were higher in patients with sarcopenia compared to those without sarcopenia. At the exercise peak, compared to patients with sarcopenia, sarcopenic patients had lower OUES (1186 ± 295 vs 1634 ± 564; P < .001), relative VO2 (16.2 ± 5.0 vs 19.5 ± 6.5 mL/kg/min; P = .011), and VE (47.3 ± 10.1 vs 63.0 ± 18.2 L/min; P < .001), while VE/VCO2 (42.9 ± 8.9 vs 38.7 ± 8.4; P = .025) was increased. OUES was positively correlated with ALM/height2 (r = 0.36; P < .0001) and handgrip strength (r = 0.31; P < .001). Hemoglobin (OR = 1.149; 95% CI, 0.842-1.570; P = .038), ALM/height2 (OR = 2.166; 95% CI, 1.338-3.504; P = .002), and VO2peak (OR = 1.377; 95% CI, 1.218-1.557; P < .001) were independently associated with OUES adjusted by cofounders.

CONCLUSIONS

Our results suggest that sarcopenia is related to impaired ventilatory response during exercise in patients with HF.

Association between psoas major muscle mass and CPET performance and long-term survival following major colorectal surgery: A retrospective cohort study

OBJECTIVES

To evaluate whether computed tomography (CT)-derived psoas major muscle measurements could predict preoperative cardiopulmonary exercise testing (CPET) performance and long-term mortality in patients undergoing major colorectal surgery and to compare predictive performance of psoas muscle measurements using 2D approach and 3D approach.

METHODS

A retrospective cohort study compliant with STROCSS standards was conducted. Consecutive patients undergoing major colorectal surgery between January 2011 and January 2017 following CPET as part of their preoperative assessment were included. Regression analyses were modelled to investigate association between the CT-derived psoas major muscle mass variables [total psoas muscle area (TPMA), total psoas muscle volume (TPMV) and psoas muscle index (PMI)] and CPET performance and mortality (1-year and 5-year). Discriminative performances of the variables were evaluated using Receiver Operating Characteristic (ROC) curve analysis.

RESULTS

A total of 457 eligible patients were included. The median TPMA and TPMV were 21 ​cm2 (IQR: 15-27) and 274 ​cm3 (IQR: 201-362), respectively. The median PMI measured via 2D and 3D approaches were 7 ​cm2/m2 (IQR: 6-9) and 99 ​cm3/m2 (IQR: 76-120), respectively. The risks of 1-year and 5-year mortality were 7.4% and 27.1%, respectively. Regression analyses showed TPMA, TPMV, and PMI can predict preoperative CPET performance and long-term mortality. However, ROC curve analyses showed no significant difference in predictive performance amongst TPMA, TPMV, and PMI.

CONCLUSION

Radiologically-measured psoas muscle mass variables may predict preoperative CPET performance and may be helpful with informing more objective selection of patients for preoperative CPET and prehabilitation.

Predischarge oxygen uptake efficiency slope has short and long-term value in the prognosis of patients after acute myocardial infarction

BACKGROUND

Patients who survive an acute myocardial infarction (AMI) have a higher risk of having a major cardiovascular event (MACE). Cardiopulmonary exercise testing (CPET) could develop prognostic stratification and prescribing exercise prescription. Patients after AMI frequently terminate CPET early with submaximal testing results. We aimed to look at the characteristics of patients' predischarge CPET variables after AMI intervention and find potential CPET variables with prognostic value.

METHODS

Between July 2012 and August 2017, we recruited patients who survived first AMI after primary percutaneous coronary intervention and received predischarge CPET retrospectively in a tertiary medical center of Taiwan. Patients were followed-up on a MACE or administrative censoring occurred (up to 5 years). To identify significant predictors of a MACE, a Cox regression model was used.

RESULTS

One hundred thirteen patients (103 men and 10 women) were studied, with an average age of 58.32 ± 12.49. MACE over 3 months, 2-years, and 5-years was 17.70%, 53.10%, and 62.83%, respectively. The oxygen uptake efficiency slope during the whole during of CPET (OUES 100) divided by body surface area (OUES 100/BSA) was found to be a significant event predictor for MACE at 3-month, 2- and 5-years. Cox regression analysis revealed that those with OUES 100/BSA <0.722 ( p = 0.004), OUES 100/BSA <0.859 ( p = 0.002), and OUES 100/BSA <0.829 ( p = 0.002) had a 7.14-fold, 3.47-fold, and 2.72-fold increased risk of 3-month, 2-year, and 5-year MACE, respectively.

CONCLUSION

It is critical to identify a submaximal predictor during CPET for patients who survive AMI. Our findings suggested that OUES could be a significant prognostic indicator in patients after first AMI in both the short and long term.

Prevalence and impact of sarcopenia in individuals with heart failure with reduced ejection fraction (the SARC-HF study): A prospective observational study protocol

Sarcopenia, a clinical syndrome primarily associated with reduced muscle mass in the elderly, has a negative impact on quality of life and survival. It can occur secondarily to other diseases such as heart failure (HF), a complex clinical syndrome with high morbidity and mortality. The simultaneous occurrence of these two conditions can worsen the prognosis of their carriers, especially in the most severe cases of HF, as in patients with reduced left ventricular ejection fraction (LVEF). However, due to the heterogeneous diagnostic criteria for sarcopenia, estimates of its prevalence present a wide variation, leading to new criteria having been recently proposed for its diagnosis, emphasizing muscle strength and function rather than skeletal muscle mass. The primary objective of this study is to evaluate the prevalence of sarcopenia and/or dynapenia in individuals with HF with reduced LVEF according to the most recent criteria, and compare the gene and protein expression of those patients with and without sarcopenia. The secondary objectives are to evaluate the association of sarcopenia and/or dynapenia with the risk of clinical events and death, quality of life, cardiorespiratory capacity, ventilatory efficiency, and respiratory muscle strength. The participants will answer questionnaires to evaluate sarcopenia and quality of life, and will undergo the following tests: handgrip strength, gait speed, dual-energy X-ray absorptiometry, respiratory muscle strength, cardiopulmonary exercise, as well as genomic and proteomic analysis, and dosage of N-terminal pro-B-type natriuretic peptide and growth differentiation factor-15. An association between sarcopenia and/or dynapenia with unfavorable clinical evolution is expected to be found, in addition to reduced quality of life, cardiorespiratory capacity, ventilatory efficiency, and respiratory muscle strength.

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.

Submaximal cardiopulmonary exercise testing to assess preoperative aerobic capacity in patients with knee osteoarthritis scheduled for total knee arthroplasty: a feasibility study

OBJECTIVE

To investigate the feasibility of submaximal cardiopulmonary exercise testing (CPET) in patients with knee osteoarthritis (OA) scheduled for primary total knee arthroplasty (TKA) surgery. Secondly, to assess their preoperative aerobic capacity.

METHODS

In this observational, single-center study, participants performed a submaximal CPET 3-6 weeks before surgery. To examine their experiences, participants completed a questionnaire and one week later they were contacted by telephone. CPET was deemed feasible when five feasibility criteria were met. Aerobic capacity was evaluated by determining the oxygen uptake (VO2) at the ventilatory anaerobic threshold (VAT) and oxygen uptake efficiency slope (OUES). OUES values were compared with two sets of normative values.

RESULTS

All feasibility criteria were met as 14 representative participants were recruited (recruitment rate: 60.9%), and all participants were able to perform the test and reached the VAT. No adverse events occurred, and all participants were positive toward submaximal CPET. The median VO2 at the VAT was 12.8 mL/kg/min (IQR 11.3-13.6). The median OUES/kg was 23.1 (IQR 20.2-28.9), 106.4% and 109.4% of predicted.

CONCLUSION

Submaximal CPET using cycle ergometry seems feasible in patients with knee OA scheduled for TKA surgery to evaluate preoperative aerobic capacity.

The oxygen uptake efficiency slope in adults with CHD: group validity

The maximal oxygen uptake (V02 max) is a well-validated measure of cardiorespiratory function that is calculated during a maximal cardiopulmonary exercise test. V02 max enables physicians to objectively assess cardiopulmonary function to aid in decision-making for patients with CHD. A significant proportion of these patients however are unable to achieve a maximal exercise test, and as such, there is a need for reliable submaximal predictors of cardiorespiratory reserve.The oxygen uptake efficiency slope represents a measure of how effectively oxygen is extracted from the lungs and taken into the body and can be calculated from a submaximal exercise test. Its reliability as a predictor of cardiorespiratory reserve has been validated in various patient populations, but there is limited evidence for its validity in adult patients with CHD.Retrospective analysis of cardiopulmonary exercise test data in 238 consecutive patients with CHD who completed a maximal cardiopulmonary exercise test at our tertiary cardiology centre demonstrated a strong correlation between peak V02 and the oxygen uptake efficiency slope (0.936). A strong correlation with peak V02 was also demonstrated when oxygen uptake efficiency slope was calculated at ventilatory anaerobic threshold (OUESVAT), 75% (OUES75), and 90% (OUES90) of the test (0.833, 0.905, 0.927 respectively).In adult patients with CHD who are unable to complete a maximal cardiopulmonary exercise test, the oxygen uptake efficiency slope is a reliable indicator of cardiopulmonary fitness which correlates strongly with peak V02 at or beyond the ventilatory anaerobic threshold. Further research is required to validate the findings in patients with less common anatomies and to assess the relationship between the oxygen uptake efficiency slope and mortality.

Open Field Exercise Testing in Pediatric Congenital Heart Disease Patients: A Subsumption of Cardiovascular Parameters

Heart failure is a common phenomenon in congenital heart disease patients. Cardiopulmonary exercise testing is used for a reliable assessment of heart failure but is still challenging, especially for young children. Implementing mobile cardiopulmonary exercise testing (CPET) can close that diagnostic gap. While average values for healthy children have already been published, this study aims to describe typical ranges of cardiovascular performance parameters of young children with congenital heart disease performing an 8-min running cardiopulmonary exercise test. Children aged 4-8 years with common congenital heart defects after corrective surgery (Tetralogy of Fallot; transposition of the great arteries and univentricular hearts after palliation) were included. The outdoor running protocol consisted of slow walking, slow jogging, fast jogging, and maximum speed running. Each exercise was performed for 2 min, except the last, in which children were instructed to keep up maximal speed as long as possible. A total of 78 children (45 male/33 female, mean age 6,24) with congenital heart disease participated in the study, of which 97% completed the CPET successfully. A detailed description of participating patients, including data on cardiac function and subjective fitness levels, is given to help physicians use this method to classify their patients. This study presents a typical range for cardiovascular performance parameters in a population of 4-8-year-old children with congenital heart disease tested in a newly developed outdoor running protocol for CPET.

Regular Practice of Physical Activity Improves Cholesterol Transfers to High-Density Lipoprotein (HDL) and Other HDL Metabolic Parameters in Older Adults

The effects of regular physical activity on two important anti-atherosclerosis functions of high-density lipoprotein (HDL), namely its capacity to receive both forms of cholesterol and its anti-oxidant function, were investigated in this study comparing older adults with young individuals. One-hundred and eight healthy adult individuals were enrolled and separated into the following groups: active older (60-80 yrs, n = 24); inactive older (60-79 yrs, n = 21); active young (20-34 yrs, n = 39); and inactive young (20-35 yrs, n = 24). All performed cardiopulmonary tests. Blood samples were collected in order to assess the following measures: lipid profile, HDL anti-oxidant capacity, paraoxonase-1 activity, HDL subfractions, and lipid transfer to HDL. Comparing active older and active young groups with inactive older and inactive young groups, respectively, the active groups presented higher HDL-C levels (p < 0.01 for both comparisons), unesterified cholesterol transfer (p < 0.01, p < 0.05), and intermediate and larger HDL subfractions (p < 0.001, p < 0.01) than the respective inactive groups. In addition, the active young group showed higher esterified cholesterol transfer than the inactive young group (p < 0.05). As expected, the two active groups had higher VO2peak than the inactive groups; VO2peak was higher in the two younger than in the two older groups (p < 0.05). No differences in unesterified and esterified cholesterol transfers and HDL subfractions were found between active young and active older groups. HDL anti-oxidant capacity and paraoxonase-1 activity were equal in all four study groups. Our data highlight and strengthen the benefits of regular practice of physical activity on an important HDL function, the capacity of HDL to receive cholesterol, despite the age-dependent decrease in VO2peak.

Oxygen Uptake Efficiency Slope and Prognosis in Heart Failure With Reduced Ejection Fraction

The prognostic utility of the oxygen uptake efficiency slope (OUES) in heart failure with reduced ejection fraction is uncertain. In this post hoc analysis of the HF-ACTION (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training) trial (n = 2,074), we tested for associations of OUES and peak oxygen uptake (VO2) with heart failure hospitalization or cardiovascular death in multivariable Cox regression models, adjusting for minute ventilation/carbon dioxide production (VE/VCO2) slope and other important confounders. Harrell's C-statistics assessed the discriminatory performance of OUES and peak VO2. Lower OUES was associated with increased risk of the outcome (quartile 1 vs 4: hazard ratio 2.1 [1.5 to 2.9, p <0.001]). Peak VO2 had greater discrimination than OUES in comparable models (e.g., C-statistic = 0.73 vs 0.70, p <0.001, respectively). In the subgroup with respiratory exchange ratio <1 (n = 358), peak VO2 was associated with the outcome (p <0.001) but OUES was not (p = 0.96). In conclusion, whereas OUES was associated with clinical outcomes independently of VE/VCO2 slope, its prognostic utility was inferior to that of peak VO2, even when measured at submaximal effort.

Prognostic Role of Metabolic Exercise Testing in Heart Failure

Heart failure is a clinical syndrome with significant heterogeneity in presentation and severity. Serial risk-stratification and prognostication can guide management decisions, particularly in advanced heart failure, when progression toward advanced therapies or end-of-life care is warranted. Each currently utilized prognostic marker carries its own set of challenges in acquisition, reproducibility, accuracy, and significance. Left ventricular ejection fraction is foundational for heart failure syndrome classification after clinical diagnosis and remains the primary parameter for inclusion in most clinical trials; however, it does not consistently correlate with symptoms and functional capacity, which are also independently prognostic in this patient population. Utilizing the left ventricular ejection fraction as the sole basis of prognostication provides an incomplete characterization of this condition and is prone to misguide medical decision-making when used in isolation. In this review article, we survey and exposit the important role of metabolic exercise testing across the heart failure spectrum, as a complementary diagnostic and prognostic modality. Metabolic exercise testing, also known as cardiopulmonary exercise testing, provides a comprehensive evaluation of the multisystem (i.e., neurological, respiratory, circulatory, and musculoskeletal) response to exercise performance. These differential responses can help identify the predominant contributors to exercise intolerance and exercise symptoms. Additionally, the aerobic exercise capacity (i.e., oxygen consumption during exercise) is directly correlated with overall life expectancy and prognosis in many disease states. Specifically in heart failure patients, metabolic exercise testing provides an accurate, objective, and reproducible assessment of the overall circulatory sufficiency and circulatory reserve during physical stress, being able to isolate the concurrent chronotropic and stroke volume responses for a reliable depiction of the circulatory flow rate in real time.

A Systematic Approach for the Interpretation of Cardiopulmonary Exercise Testing in Children with Focus on Cardiovascular Diseases

Cardiopulmonary exercise testing (CPET) is the clinical standard for children with congenital heart disease (CHD), heart failure (HF) being assessed for transplantation candidacy, and subjects with unexplained dyspnea on exertion. Heart, lung, skeletal muscle, peripheral vasculature, and cellular metabolism impairment frequently lead to circulatory, ventilatory, and gas exchange abnormalities during exercise. An integrated analysis of the multi-system response to exercise can be beneficial for differential diagnosis of exercise intolerance. The CPET combines standard graded cardiovascular stress testing with simultaneous ventilatory respired gas analysis. This review addresses the interpretation and clinical significance of CPET results with specific reference to cardiovascular diseases. The diagnostic values of commonly obtained CPET variables are discussed using an easy-to-use algorithm for physicians and trained nonphysician personnel in clinical practice.

Oxygen uptake efficiency slope in community-dwelling ambulant stroke survivors during walking and stair climbing: a cross-sectional study

BACKGROUND

Oxygen uptake efficiency slope during submaximal tests has been proposed as a more appropriate measure of aerobic capacity after suffering a stroke, since some individuals cannot tolerate maximal exercise testing. However, it has not yet been investigated whether the oxygen uptake efficiency slope is able to differentiate between healthy individuals and those who have suffered a stroke.

OBJECTIVES

To compare the oxygen uptake efficiency slope during walking and stair climbing between stroke survivors and age- and sex-matched healthy controls.

METHODS

This is a cross-sectional study in which 18 individuals who had suffered a stroke (stroke survivors) and 18 healthy controls matched for sex and age were included. Oxygen consumption and minute ventilation were collected breath-by-breath during walking (6-min Walk Test) and stair climbing. The oxygen uptake efficiency slope was estimated by the slope of the line obtained through linear regression.

RESULTS

The stroke survivors had a lower oxygen uptake efficiency slope during the 6-min Walk Test than the healthy controls (MD 498, 95% CI 122 to 873, p = .01). The between-group difference for the Stair Test was smaller and not statistically significant (MD 349, 95%CI -73 to 772, p = .10).

CONCLUSIONS

Stroke survivors had lower oxygen uptake efficiency slope during the performance of the 6-min Walk Test when compared to sex- and age-matched healthy controls. This suggests that stroke survivors have worse cardiopulmonary capacity.

Heart failure classification based on resting ejection fraction does not display a unique exercise response pattern

BACKGROUND

Heart failure with preserved (HFpEF), mildly reduced (HFmrEF) and reduced (HFrEF) ejection fraction (EF) remains a controversial categorization. Whether these three categories reflect a distinct pattern of exercise limitation in cardiopulmonary exercise testing (CPET) needs to be investigated. We aimed to analyze whether CPET variables differ between all heart failure categories (HF).

METHODS

We analyzed CPET variables of stable HFpEF (n = 123), HFmrEF (n = 31), and HFrEF (n = 153; 74 patients with and 79 patients without left ventricular assist device, LVAD) patients. The association between HF and peak oxygen consumption (VO_2peak) was used as a primary outcome, while the association between HF, oxygen uptake efficiency slope (OUES), and increase of O₂ pulse (ΔO₂ pulse) were analyzed as secondary outcomes.

RESULTS

VO_2peak displayed a consistent decline across all HF categories (19.8 ml ± 6.2/kg/min vs. 17.5 ± 7.9 ml/kg/min vs. 13.7 ± 4.0 ml/kg/min, p < 0.001). OUES only showed differences between HFpEF and HFrEF (1.8 ± 0.6 vs. 1.4 ± 0.5, p < 0.001) as well as HFmrEF and HFrEF (1.9 ± 0.9 vs. 1.4 ± 0.5, p = 0.004). ΔO₂ pulse differed between HFpEF and HFrEF (7.7 ± 3.5 ml/beat/kg*100 vs. 5.5 ± 3.0 ml/beat/kg*100, p < 0.001) as well as HFpEF and HFmrEF (7.7 ± 3.5 ml/beat/kg*100 vs. 6.3 ± 4.1 ml/beat/kg*100, p = 0.049). Outcome variables did not differ between HFrEF with and without LVAD support (VO_2peak: p = 0.364, OUES: p = 0.129, ΔO₂ pulse: p = 0.564).

CONCLUSIONS

HF did not display a distinct CPET profile. Thus, EF-based categorization does not entirely reflect exercise limitations. CPET variables could contribute to better characterize HF phenotypes.

Overshoot of the Respiratory Exchange Ratio during Recovery from Maximal Exercise Testing in Young Patients with Congenital Heart Disease

Introduction: The overshoot of the respiratory exchange ratio (RER) after exercise is reduced in patients with heart failure. Aim: The present study aimed to investigate the presence of this phenomenon in young patients with congenital heart disease (CHD), who generally present reduced cardiorespiratory fitness. Methods: In this retrospective study, patients with CHD underwent a maximal cardiopulmonary exercise testing (CPET) assessing the RER recovery parameters: the RER at peak exercise, the maximum RER value reached during recovery, the magnitude of the RER overshoot and the linear slope of the RER increase after the end of the exercise. Results: In total, 117 patients were included in this study. Of these, there were 24 healthy age-matched control subjects and 93 young patients with CHD (transposition of great arteries, Fontan procedure, aortic coarctation and tetralogy of Fallot). All patients presented a RER overshoot during recovery. Patients with CHD showed reduced aerobic capacity and cardiorespiratory efficiency during exercise, as well as a lower RER overshoot when compared to controls. RER magnitude was higher in the controls and patients with aortic coarctation when compared to those with transposition of great arteries, previous Fontan procedure, and tetralogy of Fallot. The RER magnitude was found to be correlated with the most relevant cardiorespiratory fitness and efficiency indices. Conclusions: The present study proposes new recovery indices for functional evaluation in patients with CHD. Thus, the RER recovery overshoots analysis should be part of routine CPET evaluation to further improve prognostic risk stratifications in patients with CHD.

Oxygen Uptake Efficiency Slope in South American Healthy Adults: COMPREHENSIVE REFERENCE VALUES AND INTERNATIONAL COMPARISONS

PURPOSE

The purpose of this study is to provide comprehensive reference values for oxygen uptake efficiency slope (OUES) in healthy adults. International heterogeneity was also explored through published databases.

METHODS

A cross-sectional study was conducted with treadmill cardiopulmonary exercise testing (CPX) from a Brazilian healthy adult sample, in which absolute OUES and values normalized by weight and body surface area (BSA) were calculated. Data were stratified by sex and age group. Prediction equations were calculated using age and anthropometric variables. International data were pooled and differences were explored using factorial analysis of variance or the t test, as appropriate. The OUES age-related patterns were calculated using regression analysis.

RESULTS

A total of 3544 CPX were included (1970 males and 1574 females) and the age ranged from 20-80 yr. Males had higher values than females for OUES, OUES/kg, and OUES/BSA. Lower values were found with aging and the data followed a quadratic regression curve. Reference value tables and predictive equations were provided for absolute and normalized OUES in both sexes. International comparisons of absolute OUES values among Brazilian, European, and Japanese data revealed substantial heterogeneity. The OUES/BSA measure minimized the discrepancies between Brazilian and European data.

CONCLUSIONS

Our study provided comprehensive OUES reference values in a large healthy adult sample from South America with a wide age range and included absolute and normalized values. Differences observed between Brazilian and European data were reduced in the BSA-normalized OUES.

Cardiopulmonary exercise testing for heart failure: pathophysiology and predictive markers

Despite the numerous recent advancements in therapy, heart failure (HF) remains a principle cause of both morbidity and mortality. HF with preserved ejection fraction (HFpEF), a condition that shares the prevalence and adverse outcomes of HF with reduced ejection fraction, remains poorly recognised in its initial manifestations. Cardiopulmonary exercise testing (CPET), defined as a progressive work exercise test that includes non-invasive continuous measurement of cardiovascular and respiratory parameters, provides a reliable mode to evaluate for early features and for the assessment of prognostic features of both forms of HF. While CPET measurements are standard of care for advanced HF and transplant programmes, they merit a broader clinical application in the early diagnosis and assessment of patients with HFpEF. In this review, we provide an overview of the pathophysiology of exercise intolerance in HF and discuss key findings in CPETs used to evaluate both severity of impairment and the prognostic implications.

Energy Expenditure, Body Composition, and Skeletal Muscle Oxidative Capacity in Patients with Myotonic Dystrophy Type 1

BACKGROUND

Myotonic dystrophy type 1 (DM1) patients are at risk for metabolic abnormalities and commonly experience overweight and obesity. Possibly, weight issues result from lowered resting energy expenditure (EE) and impaired muscle oxidative metabolism.

OBJECTIVES

This study aims to assess EE, body composition, and muscle oxidative capacity in patients with DM1 compared to age-, sex- and BMI-matched controls.

METHODS

A prospective case control study was conducted including 15 DM1 patients and 15 matched controls. Participants underwent state-of-the-art methodologies including 24 h whole room calorimetry, doubly labeled water and accelerometer analysis under 15-days of free-living conditions, muscle biopsy, full body magnetic resonance imaging (MRI), dual-energy x-ray absorptiometry (DEXA), computed tomography (CT) upper leg, and cardiopulmonary exercise testing.

RESULTS

Fat ratio determined by full body MRI was significantly higher in DM1 patients (56 [49-62] %) compared to healthy controls (44 [37-52] % ; p = 0.027). Resting EE did not differ between groups (1948 [1742-2146] vs (2001 [1853-2425>] kcal/24 h, respectively; p = 0.466). In contrast, total EE was 23% lower in DM1 patients (2162 [1794-2494] vs 2814 [2424-3310] kcal/24 h; p = 0.027). Also, DM1 patients had 63% less steps (3090 [2263-5063] vs 8283 [6855-11485] steps/24 h; p = 0.003) and a significantly lower VO2 peak (22 [17-24] vs 33 [26-39] mL/min/kg; p = 0.003) compared to the healthy controls. Muscle biopsy citrate synthase activity did not differ between groups (15.4 [13.3-20.0] vs 20.1 [16.6-25.8] μM/g/min, respectively; p = 0.449).

CONCLUSIONS

Resting EE does not differ between DM1 patients and healthy, matched controls when assessed under standardized circumstances. However, under free living conditions, total EE is substantially reduced in DM1 patients due to a lower physical activity level. The sedentary lifestyle of DM1 patients seems responsible for the undesirable changes in body composition and aerobic capacity.

Cardiac Structure and Cardiorespiratory Fitness in Young Male Japanese Rugby Athletes

Limited data are available on athlete's heart for rugby athletes. This study aimed to investigate cardiac structure and its relationship with cardiorespiratory fitness in young Japanese rugby athletes. A prospective cross-sectional study using echocardiography and cardiopulmonary exercise testing (CPET) was conducted on 114 male collegiate rugby players. There was a higher prevalence of increased left ventricular (LV), atrial, and aortic dimensions in the young athletes than that in previously published reports, whereas the wall thickness was within the normal range. Anthropometry and CPET analyses indicated that the forwards and backs presented muscular and endurance phenotypes, respectively. Indexed LV and aortic dimensions were significantly larger in the backs than in the forwards, and the dimensions significantly correlated with oxygen uptake measured by CPET. On the four-tiered classification for LV hypertrophy, abnormal LV geometry was found in 16% of the athletes. Notably, the resting systolic blood pressure was significantly higher in athletes with concentric abnormal geometry than in the other geometry groups, regardless of their field positions. Japanese young athletes may exhibit unique phenotypes of cardiac remodeling in association with their fitness characteristics. The four-tiered LV geometry classification potentially offers information regarding the subclinical cardiovascular risks of young athletes.

Retroperitoneal Compared to Transperitoneal Approach for Open Abdominal Aortic Aneurysm Repair Is Associated with Reduced Systemic Inflammation and Postoperative Morbidity

BACKGROUND

 In the United Kingdom, the most common surgical approach for repair of open abdominal aortic aneurysms (AAAs) is transperitoneal (TP). However, retroperitoneal (RP) approach is favored in those with more complex vascular anatomy often requiring a cross-clamp on the aorta superior to the renal arteries. This study compared these approaches in patients matched on all major demographic, comorbid, anatomic, and physiological variables.

METHODS

 Fifty-seven patients (TP: n = 24; RP: n = 33) unsuitable for endovascular aneurysm repair underwent preoperative cardiopulmonary exercise testing prior to open AAA repair. The surgical approach undertaken was dictated by individual surgeon preference. Postoperative mortality, complications, and length of hospital stay (LoS) were recorded. Patients were further stratified according to infrarenal (IR) or suprarenal/supraceliac (SR/SC) surgical clamping. Systemic inflammation (C-reactive protein) and renal function (serum creatinine and estimated glomerular filtration rate) were recorded.

RESULTS

 Twenty-three (96%) of TP patients only required an IR clamp compared with 12 (36%) in the RP group. Postoperative systemic inflammation was lower in RP patients (p = 0.002 vs. TP) and fewer reported pulmonary/gastrointestinal complications whereas renal impairment was more marked in those receiving SR/SC clamps (p < 0.001 vs. IR clamp). RP patients were defined by lower LoS (p = 0.001), while mid-/long-term mortality was low/comparable with TP, resulting in considerable cost savings.

CONCLUSION

 Despite the demands of more complicated vascular anatomy, the clinical and economic benefits highlighted by these findings justify the more routine adoption of the RP approach for complex AAA repair.

Open field stress testing: finally an optimal method in young children? Reference values for mobile cardiopulmonary exercise testing in healthy children aged 4-8 years

INTRODUCTION

Cardiopulmonary exercise testing represents the diagnostic tool for determining cardiopulmonary function. Especially in small children, exercise testing is extremely challenging. To address this problem, field testing has been implemented using small mobile devices. This study aims at using this protocol for developing normal values for cardiopulmonary exercise testing in very young children.

MATERIAL AND METHODS

Healthy children aged 4-8 years were recruited. All children were tested according to an outdoor protocol, in which they were instructed to walk, then run slowly, then a little harder and at last run at full speed. Each step lasted for 2 minutes, except the last step, in which the children were instructed to maintain as long as possible.

RESULTS

A total of 104 children (64 female/35 male, mean age 6.6 years) performed outdoor cardiopulmonary exercise testing using a mobile device. Almost all tests were completed successfully (95%). Despite a predominance of female study subjects, anthropometric values did not differ between boys and girls. V̇O₂peak/kg, respiratory exchange ratio, VT1, heart rate at VT1, and time of exercise were also comparable between sexes. Generally, a tendency of higher maximal oxygen uptake could be observed in older children.

CONCLUSION

Open field mobile cardiopulmonary exercise testing represents a novel approach in very young children. In this study, we were able to determine normal values of maximal oxygen uptake and OUES/kg for 4-8-year-old children. The method is easy to achieve and safe.

Adaptive Posture-Balance Cardiac Rehabilitation Exercise Significantly Improved Physical Tolerance in Patients with Cardiovascular Diseases

Cardiac rehabilitation (CR) requires more professional exercise modalities to improve the efficiency of treatment. Adaptive posture-balance cardiac rehabilitation exercise (APBCRE) is an emerging, balance-based therapy from clinical experience, but lacks evidence of validity. Our study aimed to observe and assess the rehabilitation effect of APBCRE on patients with cardiovascular diseases (CVDs). All participants received one-month APBCRE therapy evenly three times per week and two assessments before and after APBCRE. Each assessment included cardiopulmonary exercise testing (CPET), resting metabolic rate (RMR) detection, and three questionnaires about general health. The differences between two assessments were analyzed to evaluate the therapeutic effects of APBCRE. A total of 93 participants (80.65% male, 53.03 ± 12.02 years) were included in the analysis. After one-month APBCRE, oxygen uptake (VO2, 11.16 ± 2.91 to 12.85 ± 3.17 mL/min/kg, p < 0.01) at anaerobic threshold (AT), ventilation (VE, 28.87 ± 7.26 to 32.42 ± 8.50 mL/min/kg, p < 0.01) at AT, respiratory exchange ratio (RER, 0.93 ± 0.06 to 0.95 ± 0.05, p < 0.01) at AT and oxygen uptake efficiency slope (OUES, 1426.75 ± 346.30 to 1547.19 ± 403.49, p < 0.01) significantly improved in CVD patients. The ≤55-year group had more positive improvements (VO2 at AT, 23% vs. 16%; OUES, 13% vs. 6%) compared with the >55-year group. Quality of life was also increased after APBCRE (47.78 ± 16.74 to 59.27 ± 17.77, p < 0.001). This study proved that APBCRE was a potentially available exercise rehabilitation modality for patients with CVDs, which performed significant increases in physical tolerance and quality of life, especially for ≤55-year patients.

Cardiopulmonary exercise testing and efficacy of percutaneous coronary intervention: a substudy of the ORBITA trial

AIMS

Oxygen-pulse morphology and gas exchange analysis measured during cardiopulmonary exercise testing (CPET) has been associated with myocardial ischaemia. The aim of this analysis was to examine the relationship between CPET parameters, myocardial ischaemia and anginal symptoms in patients with chronic coronary syndrome and to determine the ability of these parameters to predict the placebo-controlled response to percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Patients with severe single-vessel coronary artery disease (CAD) were randomized 1:1 to PCI or placebo in the ORBITA trial. Subjects underwent pre-randomization treadmill CPET, dobutamine stress echocardiography (DSE) and symptom assessment. These assessments were repeated at the end of a 6-week blinded follow-up period.A total of 195 patients with CPET data were randomized (102 PCI, 93 placebo). Patients in whom an oxygen-pulse plateau was observed during CPET had higher (more ischaemic) DSE score [+0.82 segments; 95% confidence interval (CI): 0.40 to 1.25, P = 0.0068] and lower fractional flow reserve (-0.07; 95% CI: -0.12 to -0.02, P = 0.011) compared with those without. At lower (more abnormal) oxygen-pulse slopes, there was a larger improvement of the placebo-controlled effect of PCI on DSE score [oxygen-pulse plateau presence (Pinteraction = 0.026) and oxygen-pulse gradient (Pinteraction = 0.023)] and Seattle angina physical-limitation score [oxygen-pulse plateau presence (Pinteraction = 0.037)]. Impaired peak VO2, VE/VCO2 slope, peak oxygen-pulse, and oxygen uptake efficacy slope was significantly associated with higher symptom burden but did not relate to severity of ischaemia or predict response to PCI.

CONCLUSION

Although selected CPET parameters relate to severity of angina symptoms and quality of life, only an oxygen-pulse plateau detects the severity of myocardial ischaemia and predicts the placebo-controlled efficacy of PCI in patients with single-vessel CAD.

Physiologic responses to exercise in survivors of critical illness: an exploratory pilot study

Background

ICU survivors suffer from impaired physical function and reduced exercise capacity, yet the underlying mechanisms are poorly understood. The goal of this exploratory pilot study was to investigate potential mechanisms of exercise limitation using cardiopulmonary exercise testing (CPET) and 6-min walk testing (6MWT).

Methods

We enrolled adults aged 18 years or older who were treated for respiratory failure or shock in medical, surgical, or trauma ICUs at Vanderbilt University Medical Center (Nashville, TN, United States). We excluded patients with pre-existing cardiac dysfunction, a contraindication to CPET, or the need for supplemental oxygen at rest. We performed CPET and 6MWT 6 months after ICU discharge. We measured standard CPET parameters in addition to two measures of oxygen utilization during exercise (VO₂-work rate slope and VO₂ recovery half-time).

Results

We recruited 14 participants. Low exercise capacity (i.e., VO_2Peak < 80% predicted) was present in 11 out of 14 (79%) with a median VO_2Peak of 12.6 ml/kg/min [9.6–15.1] and 6MWT distance of 294 m [240–433]. In addition to low VO_2Peak, CPET findings in survivors included low oxygen uptake efficiency slope, low oxygen pulse, elevated chronotropic index, low VO₂-work rate slope, and prolonged VO₂ recovery half-time, indicating impaired oxygen utilization with a hyperdynamic heart rate and ventilatory response, a pattern seen in non-critically ill patients with mitochondrial myopathies. Worse VO₂-work rate slope and VO₂ recovery half-time were strongly correlated with worse VO_2Peak and 6MWT distance, suggesting that exercise capacity was potentially limited by impaired muscle oxygen utilization.

Conclusions

These exploratory data suggest ICU survivors may suffer from impaired muscular oxygen metabolism due to mitochondrial dysfunction that impairs exercise capacity long-term. These findings should be further characterized in future studies that include direct assessments of muscle mitochondrial function in ICU survivors.

Cardiopulmonary exercise test: A 20-year (2002-2021) bibliometric analysis

Background

The clinical application value of cardiopulmonary exercise test (CPET) has increasingly attracted attention, and related research has been increasing yearly. However, there is no summary analysis of the existing CPET literature. This is the first bibliometric analysis of publications in the CPET.

Methods

CPET-related articles published between 2002 and 2021 were retrieved from the Web of Science Core Collection database. The search was limited to Articles and Reviews in English. CiteSpace software was used to conduct collaborative network analysis of countries/regions, institutions, authors, the co-occurrence of subject categories and keywords, and co-citation analysis of authors, journals, and references.

Results

A total of 4,426 publications were identified. During the study period, the number of published articles increased yearly. Developed countries from the Americas and Europe led the field. The University of Milan was the most prolific institution, with Ross Arena and Wasserman K being the most prolific and co-cited authors in the field, respectively. Cardiovascular System &amp; Cardiology and Respiratory System were the main areas involved. Moreover, heart failure, oxygen uptake, and prognostic value were the central themes.

Conclusions

CPET had attracted widespread attention, and the number of publications will increase substantially according to the current growth trends. In the future, CPET is expected to be further adopted in large-scale clinical studies as a means of assessing the functional ability of patients to verify the efficacy of related interventions. High-quality evidence-based medical CPET-related indicators is expected to be used in clinical diseases risk prediction.

Breast cancer survivors with preserved or rescued cardiorespiratory fitness have similar cardiac, pulmonary and muscle function compared to controls

Breast cancer survivors (BCS) have a high prevalence of cardiovascular disease and low cardiorespiratory fitness (CRF). CRF is an important predictor of survival in BCS. However, the physiological factors that contribute to low CRF in BCS have not been completely elucidated. To assess differences in physiological factors (cardiac, pulmonary, muscle function) related to CRF between BCS and controls. Twenty-three BCS and 23 age-body mass index (BMI) matched controls underwent a peak cycling exercise test to determine CRF, with physiological factors measured at resting and at peak exercise. Cardiac hemodynamics (stroke volume [SV], SVindex, heart rate [HR], cardiac output [Formula: see text], and [Formula: see text]index) were evaluated using ultrasonography. Pulmonary function was evaluated using the oxygen uptake efficiency slope (OUES), ventilation to carbon dioxide production slope [Formula: see text] and breathing reserve at peak exercise (BR). Muscle oxygenation variables (oxygenated [HbO₂] deoxygenated [HHb] and total hemoglobin [Hb], and tissue oxygenation index [TSI]) were measured with near-infrared spectroscopy (NIRS). Both groups had similar CRF and similarly increased all hemodynamic variables (HR, SV, SVindex, [Formula: see text] and [Formula: see text]index) at peak exercise compared to resting (p < 0.001). BCS had higher overall HR and lower SVindex (group effect, p < 0.05). BCS had similar OUES, [Formula: see text] and BR compared to the controls. Both groups decreased TSI, and increased Hb and HHb similarly at peak exercise compared to resting (p < 0.001). Our data suggest BCS do not exhibit differences in cardiac, pulmonary, or muscle function at peak exercise compared to controls, when both groups have similar CRF and physical activity.

'Fit for surgery': The relationship between cardiorespiratory fitness and postoperative outcomes

New Findings

What is the topic of this review?

The relationships and physiological mechanisms underlying the clinical benefits of cardiorespiratory fitness (CRF) in patients undergoing major intra‐abdominal surgery.

What advances does it highlight?

Elevated CRF reduces postoperative morbidity/mortality, thus highlighting the importance of CRF as an independent risk factor. The vascular protection afforded by exercise prehabilitation can further improve surgical risk stratification and postoperative outcomes.

Abstract

Surgery accounts for 7.7% of all deaths globally and the number of procedures is increasing annually. A patient's ‘fitness for surgery’ describes the ability to tolerate a physiological insult, fundamental to risk assessment and care planning. We have evolved as obligate aerobes that rely on oxygen (O₂). Systemic O₂ consumption can be measured via cardiopulmonary exercise testing (CPET) providing objective metrics of cardiorespiratory fitness (CRF). Impaired CRF is an independent risk factor for mortality and morbidity. The perioperative period is associated with increased O₂ demand, which if not met leads to O₂ deficit, the magnitude and duration of which dictates organ failure and ultimately death. CRF is by far the greatest modifiable risk factor, and optimal exercise interventions are currently under investigation in patient prehabilitation programmes. However, current practice demonstrates potential for up to 60% of patients, who undergo preoperative CPET, to have their fitness incorrectly stratified. To optimise this work we must improve the detection of CRF and reduce potential for interpretive error that may misinform risk classification and subsequent patient care, better quantify risk by expressing the power of CRF to predict mortality and morbidity compared to traditional cardiovascular risk factors, and improve patient interventions with the capacity to further enhance vascular adaptation. Thus, a better understanding of CRF, used to determine fitness for surgery, will enable both clinicians and exercise physiologists to further refine patient care and management to improve survival.

Abnormal exercise adaptation after varying severities of COVID-19: A controlled cross-sectional analysis of 392 survivors

The multisystem impairment promoted by COVID-19 may be associated with a reduction in exercise capacity. Cardiopulmonary abnormalities can change across the acute disease severity spectrum. We aimed to verify exercise physiology differences between COVID-19 survivors and SARS-CoV-2-naïve controls and how illness severity influences exercise limitation. A single-center cross-sectional analysis of prospectively collected data from COVID-19 survivors who underwent cardiopulmonary exercise testing (CPET) in their recovery phase (x =50[36;72] days). Patients with COVID-19 were stratified according to severity as mild [M-Cov (outpatient)] vs severe/critical [SC-Cov(inpatients)] and were compared with SARS-CoV-2-naïve controls (N-Cov). Collected information included demographics, anthropometrics, previous physical exercise, comorbidities, lung function test and CPET parameters. A multivariate logistic regression analysis was performed to identify low aerobic capacity (LAC) predictors post COVID-19. Of the 702 included patients, 310 (44.2%), 305 (43.4%) and 87 (12.4%) were N-Cov, M-Cov and SC-Cov, respectively. LAC was identified in 115 (37.1%), 102 (33.4%), and 66 (75.9%) of N-CoV, M-CoV and SC-CoV, respectively (p < 0.001). SC-Cov were older, heavier with higher body fat, more sedentary lifestyle, more hypertension and diabetes, lower forced vital capacity, higher prevalence of early anaerobiosis, ventilatory inefficiency and exercise-induced hypoxia than N-Cov. M-Cov had lower weight, fat mass, and coronary disease prevalence and did not demonstrate more CEPT abnormalities than N-Cov. After adjustment for covariates, SC-Cov was an independent predictor of LAC (OR = 2.7; 95% CI, 1.3-5.6). Almost two months after disease onset, SC-CoV presented several exercise abnormalities of oxygen uptake, ventilatory adaptation and gas exchange, including a high prevalence of LAC.

An Individualized Exercise Intervention for People with Multiple Myeloma—Study Protocol of a Randomized Waitlist-Controlled Trial

People with multiple myeloma (MM) are second only to people with lung cancer for the poorest reported health-related quality of life (HRQoL) of all cancer types. Whether exercise can improve HRQoL in MM, where bone pain and lesions are common, requires investigation. This trial aims to evaluate the efficacy of an exercise intervention compared with control on HRQoL in people with MM. Following baseline testing, people with MM (n = 60) will be randomized to an exercise (EX) or waitlist control (WT) group. EX will complete 12-weeks of supervised (24 sessions) and unsupervised (12 sessions) individualized, modular multimodal exercise training. From weeks 12–52, EX continue unsupervised training thrice weekly, with one optional supervised group-based session weekly from weeks 12–24. The WT will be asked to maintain their current activity levels for the first 12-weeks, before completing the same protocol as EX for the following 52 weeks. Primary (patient-reported HRQoL) and secondary (bone health and pain, fatigue, cardiorespiratory fitness, muscle strength, body composition, disease response, and blood biomarkers) outcomes will be assessed at baseline, 12-, 24- and 52-weeks. Adverse events, attendance, and adherence will be recorded and cost-effectiveness analysis performed. The findings will inform whether exercise should be included as part of standard myeloma care to improve the health of this unique population.

Five-year changes in objectively measured cardiorespiratory fitness, physical activity, and sedentary time in mid-to-late adulthood

This study examined 5-year changes in cardiorespiratory fitness, physical activity, and sedentary time in mid-to-late aged adults. Fifty-seven participants completed baseline and follow-up treadmill exercise tests and physical activity monitoring. We observed a 14% decline in fitness (p < 0.001), 12% decrease in physical activity (p = 0.010), and non-significant increase in sedentary time (p = 0.196). Age was negatively associated with 5-year change in physical activity (r = -0.31; p = 0.02) and this decline was strongest among APOE ε4 carriers (g = -0.75). Novelty: Cardiorespiratory fitness and physical activity significantly declined from mid-to-late adulthood, these findings were most pronounced among older adults and those with genetic risk for Alzheimer's disease.

Cardiopulmonary exercise test in patients with refractory angina: functional and ischemic evaluation

OBJECTIVES

Refractory angina (RA) is a chronic condition clinically characterized by low effort tolerance; therefore, physical stress testing is not usually requested for these patients. Cardiopulmonary exercise testing (CPET) is considered a gold standard examination for functional capacity evaluation, even in submaximal tests, and it has gained great prominence in detecting ischemia. The authors aimed to determine cardiorespiratory capacity by using the oxygen consumption efficiency slope (OUES) in patients with refractory angina. The authors also studied the O₂ pulse response by CPET and the association of ischemic changes with contractile modifications by exercise stress echocardiography (ESE).

METHODS

Thirty-one patients of both sexes, aged 45 to 75 years, with symptomatic (Canadian Cardiovascular Society class II to IV) angina who underwent CPET on a treadmill and exercise stress echocardiography on a lower limb cycle ergometer were studied. ClinicalTrials.gov: NCT03218891.

RESULTS

The patients had low cardiorespiratory capacity (OUES of 1.74 ± 0.4 L/min; 63.9±14.7% of predicted), and 77% of patients had a flattening or drop in O₂ pulse response. There was a direct association between Heart Rate (HR) at the onset of myocardial ischemia detected by ESE and HR at the onset of flattening or drop in oxygen pulse response detected by CPET (R = 0.48; p = 0.019).

CONCLUSION

Patients with refractory angina demonstrate low cardiorespiratory capacity. CPET shows good sensitivity for detecting abnormal cardiovascular response in these patients with a significant relationship between flattening O₂ pulse response during CEPT and contractile alterations detected by exercise stress echocardiography.

Exercise capacity after total cavopulmonary anastomosis: a longitudinal paediatric and adult study

AIMS

Fontan palliation is a surgical strategy for patients with complex congenital heart disease, in whom biventricular circulation cannot be achieved. Long-term survival is negatively affected by the absence of sub-pulmonary ventricle and increased systemic venous pressure. Exercise capacity is a known predictor of overall survival and quality of life in congenital heart defects. We aim to track individual trends of peak oxygen uptake (V̇O₂ peak) after total cavopulmonary connection (TCPC), identify predictors of deterioration, and derive a disease-specific reference V̇O₂ peak dataset.

METHODS AND RESULTS

A retrospective study of serial cardiopulmonary exercise testing (CPET) data, gathered from all patients who underwent TCPC in the Czech Republic between 1992 and 2016. Of 354 consecutive patients with TCPC, 288 (81.4%) patients underwent one or more CPETs yielding 786 unique V̇O₂ peak values used as a reference dataset. Longitudinal data were available in 206 (58.2%) patients, who underwent a median (inter-quartile range) of 3.0 (2.0-5.0) CPETs over a mean (standard deviation) of 8.9 (5.5) years. The decline of exercise capacity with age was linear and not faster than in healthy peers (P = 0.47), but relative values of V̇O₂ peak in TCPC patients were 12.6 mL/min/kg lower. Single ventricular morphology and pulmonary artery size had no significant influence on the exercise capacity dynamics. V̇O₂ peak decline correlated negatively with the trend of body mass index z-score (P = 0.006) and was faster in women than men (P = 0.008).

CONCLUSIONS

Total cavopulmonary connection patients have significantly reduced exercise capacity. The age-related decline paralleled the healthy population and correlated negatively with the body mass index trend. The presented V̇O₂ peak reference dataset may help the clinicians to grade the severity of exercise capacity impairment in individual TCPC patients.

Serial Cardiopulmonary Exercise Testing in Patients after Extracardiac Conduit Total Cavopulmonary Connection for Single-Ventricle Hearts: An Observational Study

OBJECTIVE

To analyze the aerobic fitness and evolution of exercise tolerance in patients with single-ventricle physiology after total cavopulmonary connection (TCPC) with an extracardiac conduit (ECC).

STUDY DESIGN

This retrospective cohort study included patients with previous ECC-TCPC who underwent cardiopulmonary exercise testing (CPET) between September 2010 and September 2019. Patients who completed at least 2 tests (≥6 months apart) with adequate levels of effort were recruited for the serial CPET evaluation.

RESULTS

We identified 70 patients (50% male) with a mean age of 6.45 ± 5.14 years at ECC-TCPC and 15.67 ± 5.03 years at the initial CPET. The peak oxygen consumption (peak VO₂) to predicted value (peak PD) was 55.90 ± 16.81%. Twenty of the 70 identified patients (50% male) were recruited for serial analysis. The average number of CPETs was 2.6 per patient. The average duration from the first CPET to the last CPET was 3.64 years. The peak VO₂ and PD increased slowly, with mean rates of 38.77 ± 129.01 mL/min and 1.66 ± 6.40%, respectively, during the study period.

CONCLUSIONS

Although the patients had lower exercise tolerance after ECC-TCPC compared with their normal peers, exercise tolerance appears to have been preserved over the adolescent period in those who underwent serial testing after ECC-TCPC.

The validation of oxygen uptake efficiency slope in patients with stroke

To evaluate the real aerobic capacity is difficult due to impaired limbs function in stroke patients. Oxygen uptake efficiency slope (OUES) could represent the aerobic capacity in submaximal exercise test. Hence, we designed this observational study to investigate the application of the OUES for evaluating aerobic capacity in these patients.Thirty-seven stroke patients were classified into 2 groups according to their Brunnstrom stage of affected lower limbs. Patients underwent cardiopulmonary exercise testing to assess cardiorespiratory fitness. Minute ventilation and oxygen consumption were measured, and OUES was calculated, compared with healthy reference values, and correlated with the peak oxygen consumption. The predictive validity of submaximal OUES was derived.Study participants' OUES (median 566.2 [IQR, 470.0-711.6]) was 60% of healthy reference values and correlated positively with the peak oxygen consumption (r = 0.835) (P < .01). The predictive validity of oxygen uptake efficiency slope at 50% of maximal exercise duration (OUES50) and oxygen uptake efficiency slope at 75% of maximal exercise duration (OUES75) for oxygen uptake efficiency slope at 100% of maximal exercise duration (OUES100) was 0.877 and 0.973, respectively (P < .01). The OUES50, OUES75, and OUES100 groups were not significantly different; agreement of submaximal and maximal OUES values was strong.OUES is a valuable submaximal index for evaluating cardiorespiratory fitness in stroke patients. Moderate-to-high concurrent validity of this parameter with peak oxygen consumption and the high predictive validity of OUES50 and OUES75 for OUES100 suggest maximal exercise testing in stroke patients who cannot reach maximal exercise is unnecessary.

Dynamic physiological responses in obese and non-obese adults submitted to cardiopulmonary exercise test

PURPOSE

Obese individuals have reduced performance in cardiopulmonary exercise testing (CPET), mainly considering peak values of variables such as oxygen uptake ([Formula: see text]), carbon dioxide production ([Formula: see text]), tidal volume (Vt), minute ventilation ([Formula: see text]) and heart rate (HR). The CPET interpretation and prognostic value can be improved through submaximal ratios analysis of key variables like [Formula: see text], [Formula: see text], [Formula: see text] [Formula: see text] and oxygen uptake efficiency slope (OUES). The obesity influence on these responses has not yet been investigated. Our purpose was to evaluate the influence of adulthood obesity on maximal and submaximal physiological responses during CPET, emphasizing the analysis of submaximal dynamic variables.

METHODS

We analyzed 1,594 CPETs of adults (755 obese participants, Body Mass Index ≥ 30 kg/m2) and compared the obtained variables among non-obese (normal weight and overweight) and obese groups (obesity classes I, II and III) through multivariate covariance analyses.

RESULT

Obesity influenced the majority of evaluated maximal and submaximal responses with worsened CPET performance. Cardiovascular, metabolic and gas exchange variables were the most influenced by obesity. Other maximal and submaximal responses were altered only in morbidly obese. Only a few cardiovascular and ventilatory variables presented inconsistent results. Additionally, Vtmax, [Formula: see text], Vt/Inspiratory Capacity, Vt/Forced Vital Capacity, Lowest [Formula: see text], [Formula: see text], and the y-intercepts of [Formula: see text] did not significantly differ regardless of obesity.

CONCLUSION

Obesity expressively influences the majority of CPET variables. However, the prognostic values of the main ventilatory efficiency responses remain unchanged. These dynamic responses are not dependent on maximum effort and may be useful in detecting incipient ventilatory disorder. Our results present great practical applicability in identifying exercise limitation, regardless of overweight and obesity.

Responders and non-responders to aerobic exercise training: beyond the evaluation of V˙O2max

The evaluation of the maximal oxygen uptake ( V ˙ O 2 max ) following exercise training is the classical assessment of training effectiveness. Research has lacked in investigating whether individuals that do not respond to the training intervention ( V ˙ O 2 max ), also do not improve in other health-related parameters. We aimed to investigate the cardiovascular and metabolic adaptations (i.e., performance, body composition, blood pressure, vascular function, fasting blood markers, and resting cardiac function and morphology) to exercise training among participants who showed different levels of V ˙ O 2 max responsiveness. Healthy sedentary participants engaged in a 6-week exercise training program, three times a week. Our results showed that responders had a greater increase in peak power output, second lactate threshold, and microvascular responsiveness, whereas non-responders had a greater increase in cycling efficiency. No statistical differences were observed in body composition, blood pressure, fasting blood parameters, and resting cardiac adaptations. In conclusion, our study showed, for the first time, that in addition to the differences in the V ˙ O 2 max , a greater increase in microvascular responsiveness in responders compared to non-responders was observed. Additionally, responders and non-responders did not show differences in the adaptations on metabolic parameters. There is an increasing need for personalized training prescription, depending on the target clinical outcome.

Two-minute exercise testing is sufficient to estimate maximal cardiorespiratory fitness in people with epilepsy

We aimed to examine the agreement between submaximal cardiopulmonary exercise testing (CPET) measures and peak oxygen consumption (VO_2peak) in adults with epilepsy. Data from a randomized controlled trial with adults with epilepsy (N = 21) were analyzed. VO_2peak was assessed using indirect calorimetry during a treadmill graded maximal CPET. Oxygen uptake efficiency slope (OUES) was calculated from the relationship between oxygen uptake and minute ventilation during the entire test (OUES_peak) and the first 2 (OUES_2min), 3 (OUES_3min), and 4 (OUES_4min) minutes of the CPET. The strength of the association between measures was tested by Pearson correlation. Linear regression models were used to predict VO_2peak based on OUES from the different testing durations. Agreement between measured and predicted maximal values was tested using intraclass correlation coefficient (ICC) and Bland-Altman plots. OUES_2min, OUES_3min, and OUES_4min were highly associated with absolute (r = 0.84, r = 0.76, r = 0.75, respectively) and relative (r = 0.84, r = 0.78, r = 0.78, respectively) VO_2peak. Agreement (ICC = 0.83) between CPET-measured and OUES-predicted VO_2peak values was stronger with OUES_2min than the other time-based OUES markers. Bland-Altman plot showed satisfactory agreement between predicted and measured CPET measures with the narrowest limits of agreement observed with the OUES_2min. No potential bias was identified between these two measurements (p = 0.33). Changes in absolute (r = 0.77) and relative (r = 0.88) VO₂peak were highly associated with the change in OUES_2min. OUES_2min can be used as a surrogate for maximal cardiorespiratory fitness in adults with epilepsy. Studies with larger samples size are encouraged to confirm our findings in a more heterogeneous population.

Oxygen uptake efficiency slope: A submaximal test evaluation tool that provides cardiopulmonary reserve data in individuals with Parkinson's disease

BACKGROUND

Oxygen uptake efficiency slope (OUES) is a method for investigating cardiorespiratory fitness and is proposed as an alternative to overcome the limitations of traditional measures such as peak oxygen consumption (VO_2peak) for patients who do not achieve a maximum response, such as in Parkinson's disease (PD).

OBJECTIVE

To assess the performance of individuals with PD during the six-minute walk test (6MWT) using the OUES.

METHODS

This is an observational cross-sectional study including 12 individuals with PD and 12 healthy controls. Participants performed the 6MWT along with an analysis of exhaled gas kinetics. The OUES was determined from the last 16 s of the walk test. Multiple linear regression analyses were computed to explore associations between the independent (OUES) and the dependent variables (VO_2peak) controlled by group.

RESULTS

The OUES was associated to VO_2peak on the 6MWT (β=0.24, p<0.01) in individuals with PD. The PD group had low performance on the 6MWT with a shorter distance walked (mean difference: -113.1 m; 95% CI: -203.2, -59.1) and worse cardiopulmonary condition with lower OUES values (mean difference: -0.52 [l/minO₂]/[l/minVE]; 95% CI: -0.83, -0.21) found in this same group.

CONCLUSIONS

Our results suggest that OUES is related to VO_2peak during the 6MWT, and therefore it could be used as a submaximal test evaluation tool which provides cardiopulmonary reserve data in individuals with PD.

Oxygen Supply System Management in an Overweight Adult after 12 Months in Antarctica-Study Case

The aim of the study was to try to determine the functional state of the respiratory system, i.e., selected parameters and indicators of physiological systems responsible for the supply of oxygen at all stages of its delivery in people as their body weight increases from normal weight to overweight. The studies include an analysis of test results of functional respiratory system state (FSD) indicators of a 30-year-old and 170-cm tall man. Measurements of FSD were conducted two times: the first time before an expedition to Antarctica at 70 kg (normal body weight); the next measurements were taken a year later, after coming back from the expedition, at 82 kg (overweight). When analyzing the functional respiratory system state in terms of the effect of overweight it was found that the maintenance of the oxygen homeostasis in those conditions occurred at the level of a compensated hypoxic state. That is why the decision to engage in physical activity can be made only if we are sure that significant destructive additive effects of both types of hypoxic influences (from excessive body weight and from the physical activity) are not overlapping.

Individual cardiovascular responsiveness to work-matched exercise within the moderate- and severe-intensity domains

Purpose

We investigated the cardiovascular individual response to 6 weeks (3×/week) of work-matched within the severe-intensity domain (high-intensity interval training, HIIT) or moderate-intensity domain (moderate-intensity continuous training, MICT). In addition, we analyzed the cardiovascular factors at baseline underlying the response variability.

Methods

42 healthy sedentary participants were randomly assigned to HIIT or MICT. We applied the region of practical equivalence-method for identifying the levels of responders to the maximal oxygen uptake (V̇O_2max) response. For investigating the influence of cardiovascular markers, we trained a Bayesian machine learning model on cardiovascular markers.

Results

Despite that HIIT and MICT induced significant increases in V̇O_2max, HIIT had greater improvements than MICT (p < 0.001). Greater variability was observed in MICT, with approximately 50% classified as “non-responder” and “undecided”. 20 “responders”, one “undecided” and no “non-responders” were observed in HIIT. The variability in the ∆V̇O_2max was associated with initial cardiorespiratory fitness, arterial stiffness, and left-ventricular (LV) mass and LV end-diastolic diameter in HIIT; whereas, microvascular responsiveness and right-ventricular (RV) excursion velocity showed a significant association in MICT.

Conclusion

Our findings highlight the critical influence of exercise-intensity domains and biological variability on the individual V̇O_2max response. The incidence of “non-responders” in MICT was one third of the group; whereas, no “non-responders” were observed in HIIT. The incidence of “responders” was 11 out of 21 participants in MICT, and 20 out of 21 participants in HIIT. The response in HIIT showed associations with baseline fitness, arterial stiffness, and LV-morphology; whereas, it was associated with RV systolic function in MICT.

Maximal oxygen consumption and oxygen uptake efficiency in adolescent males

BACKGROUND/OBJECTIVE

Measures of oxygen uptake efficiency (OUE) have been used to evaluate cardiorespiratory fitness (CRF) in adolescents unable to perform maximal exercise. The oxygen uptake efficiency slope (OUES) and oxygen uptake efficiency plateau (OUEP) have been proposed as surrogates for maximal oxygen consumption (V̇O2max). We assessed the validity of the OUES and OUEP as predictors of V̇O2max in healthy male adolescents.

METHODS

Sixty-three healthy male adolescents aged 15.40 ± 0.34 years underwent an incremental treadmill test to determine V̇O2max, OUES and OUEP. OUE throughout the test was assessed by dividing each V̇O2 value by the corresponding minute ventilation (V̇E) value. OUEP was determined as the 90 s average highest consecutive values for OUE. OUES was determined using data up to the ventilatory threshold (VT) by calculating the slope of the linear relation between V̇O2 and the logarithm of V̇E.

RESULTS

Limits of agreement for V̇O2max predicted by OUES (±13.3 mL kg-1.min-1) and OUEP (±16.7 mL kg-1.min-1) relative to V̇O2max were wide and a magnitude bias was found for OUES and OUEP as predictors of V̇O2max (p < 0.001).

CONCLUSION

The OUES and OUEP do not accurately predict V̇O2max in male adolescents and should not replace V̇O2max when assessing CRF in this population.

Determinants of maximal oxygen uptake in patients with heart failure

Aims

Maximum oxygen uptake (VO_2max) is an essential parameter to assess functional capacity of patients with heart failure (HF). We aimed to identify clinical factors that determine its value, as they have not been well characterized yet.

Methods

We conducted a retrospective, observational, single‐centre study of 362 consecutive patients with HF who underwent cardiopulmonary exercise testing (CPET) as part of standard clinical assessment since 2009–2019. CPET was performed on treadmill, according to Bruce's protocol (n = 360) or Naughton's protocol (n = 2). We performed multivariable linear regression analyses in order to identify independent clinical predictors associated with peak VO_2max.

Results

Mean age of study patients was 57.3 ± 10.9 years, mean left ventricular ejection fraction was 32.8 ± 14.2%, and mean VO_2max was 19.8 ± 5.2 mL/kg/min. Eighty‐nine (24.6%) patients were women, and 114 (31.5%) had ischaemic heart disease. Multivariable linear regression analysis identified six independent clinical predictors of VO_2max, including NYHA class (B coefficient = −2.585; P < 0.001), age (B coefficient per 1 year = −0.104; P < 0.001), tricuspid annulus plane systolic excursion (B coefficient per 1 mm = +0.209; P < 0.001), body mass index (B coefficient per 1 kg/m² = −0.172; P = 0.002), haemoglobin (B coefficient per 1 g/dL = +0.418; P = 0.007) and NT‐proBNP (B coefficient per 1000 pg/mL = −0.142; P = 0.019).

Conclusions

The severity of HF (NYHA class, NT‐proBNP) as well as age, body composition and haemoglobin levels influence significantly exercise capacity. In patients with HF, the right ventricular systolic function is of greater importance for the physical capacity than the left ventricular systolic function.

A novel exercise testing algorithm to diagnose mitochondrial myopathy

INTRODUCTION

Oxygen uptake efficiency slope (OUES) is a noninvasive cardiopulmonary exercise testing (CPET) measurement based on oxygen uptake (V˙O₂ ) and minute ventilation (V˙E) and is a marker of the efficiency of oxygen utilization by the body. However, it has not been studied in mitochondrial disorders. We explored noninvasive CPET parameters, including OUES, as a way to reliably diagnose mitochondrial myopathy.

METHODS

We performed cycle ergometer maximal exercise testing on definite and suspected mitochondrial myopathy subjects (MM-D and MM-S) and their age- and sex-matched controls. OUES was corrected for body surface area (OUES/BSA) to eliminate the effect of body size.

RESULTS

A total of 40 participants, including 20 MM-D (n = 13; 6 males; aged 14-64 years) and 7 MM-S (5 males, aged 11-30 years) subjects and 20 controls, completed the study. MM-D subjects showed lower aerobic fitness than controls. OUES/BSA was lower in MM-D subjects, suggesting inefficient oxygen utilization. Area under the curve (AUC) and 95% confidence interval (CI) for OUES/BSA (AUC, 0.91; 95% CI, 0.80-1.00), peak V˙O₂ percent predicted (AUC, 0.95; 95% CI, 0.86-1.00), and V˙O₂ /work slope (AUC, 0.94; 95% CI, 0.85-1.00) showed excellent ability to diagnose mitochondrial myopathy in MM-D subjects. We applied a diagnostic approach based on the parameters just noted to MM-S subjects and their controls and were able to support or disprove the diagnosis of mitochondrial myopathy.

DISCUSSION

We proposed and applied an approach based on the aformentioned three CPET parameters to diagnose mitochondrial myopathy reliably and found it to be clinically useful.

Predictive Value of Cardiopulmonary Exercise Testing Parameters in Ambulatory Advanced Heart Failure

OBJECTIVES

This study sought to determine cardiopulmonary exercise (CPX) predictors of the combined outcome of durable mechanical circulatory support (MCS), transplantation, or death at 1 year among patients with ambulatory advanced heart failure (HF).

BACKGROUND

Optimal CPX predictors of outcomes in contemporary ambulatory advanced HF patients are unclear.

METHODS

REVIVAL (Registry Evaluation of Vital Information for ventricular assist devices [VADs] in Ambulatory Life) enrolled 400 systolic HF patients, INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) profiles 4-7. CPX was performed by 273 subjects 2 ± 1 months after study enrollment. Discriminative power of maximal (peak oxygen consumption [peak VO₂]; VO₂ pulse, circulatory power [CP]; peak systolic blood pressure • peak VO₂], peak end-tidal pressure CO₂ [PEtCO₂], and peak Borg scale score) and submaximal CPX parameters (ventilatory efficiency [VE/VCO₂ slope]; VO₂ at anaerobic threshold [VO₂AT]; and oxygen uptake efficiency slope [OUES]) to predict the composite outcome were assessed by univariate and multivariate Cox regression and Harrell's concordance statistic.

RESULTS

At 1 year, there were 39 events (6 transplants, 15 deaths, 18 MCS implantations). Peak VO₂, VO₂AT, OUES, peak PEtCO₂, and CP were higher in the no-event group (all p < 0.001), whereas VE/VCO₂ slope was lower (p < 0.0001); respiratory exchange ratio was not different. CP (hazard ratio [HR]: 0.89; p = 0.001), VE/VCO₂ slope (HR: 1.05; p = 0.001), and peak Borg scale score (HR: 1.20; p = 0.005) were significant predictors on multivariate analysis (model C-statistic: 0.80).

CONCLUSIONS

Among patients with ambulatory advanced HF, the strongest maximal and submaximal CPX predictor of MCS implantation, transplantation, or death at 1 year were CP and VE/VCO_2, respectively. The patient-reported measure of exercise effort (Borg scale score) contributed substantially to the prediction of outcomes, a surprising and novel finding that warrants further investigation. (Registry Evaluation of Vital Information for VADs in Ambulatory Life [REVIVAL]; NCT01369407).

Impact of peak respiratory exchange ratio on the prognostic power of symptoms-limited exercise testing using Bruce protocol in patients with Fontan physiology

OBJECTIVES

We evaluated the impact of peak respiratory exchange ratio on the prognostic values of cardiopulmonary exercise variables during symptoms-limited incremental exercise tests in patients with Fontan physiology.

METHODS

Retrospective single-centre chart review study of Fontan patients who underwent exercise testing using the Bruce protocol between 2014 and 2018 and follow-up.

RESULTS

A total of 34 patients (age > 18 years) had a Borg score of ≥7 on the Borg 10-point scale, but only 50% of patients achieved a peak respiratory exchange ratio of ≥ 1.10 (maximal test). Peak oxygen consumption, percent-predicted peak oxygen consumption, and peak oxygen consumption at the ventilatory threshold was reduced significantly in patients with a peak respiratory exchange ratio of < 1.10. Peak oxygen consumption and percent-predicted peak oxygen consumption was positively correlated with peak respiratory exchange ratio values (r = 0.356, p = 0.039). After a median follow-up of 21 months, cardiac-related events occurred in 16 (47%) patients, with no proportional differences in patients due to their respiratory exchange ratio (odds ratio, 0.62; 95% CI: 0.18-2.58; p = 0.492). Multivariate Cox proportional hazard analysis showed percent-predicted peak oxygen consumption, peak heart rate, and the oxygen uptake efficient slope were highly related to the occurrence of events in patients only with a peak respiratory exchange ratio of ≥ 1.10.

CONCLUSIONS

The value of peak cardiopulmonary exercise variables is limited for the determination of prognosis and assessment of interventions in Fontan patients with sub-maximal effort. Our findings deserve further research and clinical application.