Peak oxygen uptake reference values for cycle ergometry for the healthy Dutch population: data from the LowLands Fitness Registry

Unlocking insights: Clinical associations from the largest 6-minute walk test collection via the my Heart Counts Cardiovascular Health Study, a fully digital smartphone platform

BACKGROUND

The six-minute walk test (6MWT) is a prognostic sub-maximal exercise test used clinically as a measure of functional capacity. With the emergence of advanced sensors, 6MWTs are being performed remotely via smartphones and other devices. The My Heart Counts Cardiovascular Health Study is a smartphone application that serves as a digital platform for studies of human cardiovascular health, and has been used to perform 30,475 6MWTs on 8922 unique participants.

OBJECTIVE

As our 30,475 6MWTs represent the largest such collection of data available, we sought to identify associations with measured demographic and clinical variables with 6MWT distance at enrollment and separately determine if use of the My Heart Counts smartphone application led to changes in 6MWT distance.

METHODS AND RESULTS

We present the public data release of our 30,475 6MWTs and the launch of a webpage-based data viewer of summary-level statistics, to compare the functional capacity of an individual by their age, gender, height, weight, and disease status (https://mhc-6mwts.streamlit.app). Using multivariable regression, we report associations of demographic and clinical variables with baseline 6MWT distance (N = 3606), validating prior associations with age, male gender, height, and baseline physical activity level with 6MWT distance. We also report associations of 6MWT baseline distance with employment status (+12.4 m ±4.9 m, P = 0.011) and feeling depressed (-3.65 m, ±0.79 m, P < 0.001). We separately found that cardiovascular disease status was significantly associated with decreased 6MWT distance for atrial fibrillation (-24.9 m ±7.8 m, P = 0.0013), peripheral artery disease (-41.7 m ±12.5 m, P < 0.001), and pulmonary arterial hypertension (-76.3 m ±24.8 m, P = 0.0022). Heart failure was associated with decreased 6MWT distance but was not statistically significant (-25.5 m ±14.5 m, P = 0.078). In a subset of participants who conducted repeat 6MWTs separated by at least 1 week but no greater than 3 months (N = 1129), we found that use of the My Heart Counts app was associated with a statistically significant increase in 6MWT distance (+17.5 m ±7.85 m, P < 0.001).

CONCLUSIONS

We validate previously identified associations from clinic-performed 6MWTs, demonstrating the utility of a mobile method in collecting 6MWT data for clinicians and researchers. We also demonstrate that use of the My Heart Counts app is associated with small, but significant increases in 6MWT distance. Given the importance of 6MWTs in assessment of functional capacity, our publicly-available data will serve an important purpose as a health and disease-specific reference for investigators worldwide.

Quality of Life in the Danish Fontan Population is Unchanged Over the Past Decade-A Nationwide Longitudinal Study

Knowledge about health-related quality of life (HRQoL) over time in Fontan patients is sparse. We aimed to describe HRQoL over a ten-year period in a population-based Fontan cohort. Further, we compared HRQoL in Fontan patients with the general population. In 2011, Danish Fontan patients were invited to participate in a nationwide study assessing HRQoL. Depending on age, 152 participants filled out either the Pediatric Quality of Life Inventory or the 36-Item Short Form Health Survey. After a decade, patients from the initial study were invited to participate in a follow-up study. All were given the same questionnaire as in the first study, plus the 12-Item Short Form Health Survey (SF-12) as part of the Danish National Health Survey. HRQoL over time was described, and SF-12 scores were compared with the general population. A total of 109 Fontan patients completed the questionnaires in both studies. The mean patient age was 14.9 ± 6.6 years and 25.6 ± 6.5 years respectively. Despite an increase in complications, HRQoL did not decrease during the study period. Physical HRQoL scores were lower than mental HRQoL scores at both time points. The SF-12 physical component score was significantly lower in Fontan patients than in the general population (median score 52 vs. 56, p < 0.001), while the SF-12 mental component score was comparable (median score 51 vs. 50, p = 0.019). HRQoL remained stable over a ten-year period in a contemporary Danish Fontan cohort. Still, the physical HRQoL remained significantly lower than that of the general population.

Peak Oxygen Consumption Scaled to Body Composition Is Associated With Mortality and Morbidity in People With a Fontan Circulation

BACKGROUND

Peak oxygen consumption (peak V ̇ $$ \dot{\mathrm{V}} $$ O2) is traditionally scaled by body mass, but it is most appropriately scaled by fat-free mass. However, it is unknown whether peak V ̇ $$ \dot{\mathrm{V}} $$ O2 scaled by fat-free mass is associated with mortality and morbidity in people with a Fontan circulation. The aim of this study was to assess the associations between different expressions of peak V ̇ $$ \dot{\mathrm{V}} $$ O2 with mortality and morbidity in people with a Fontan circulation.

METHODS AND RESULTS

Eighty-seven participants (aged 24.1±7.3 years; 53% women) with a Fontan circulation completed a cardiopulmonary exercise test and a dual-energy x-ray absorptiometry scan. Cox proportional hazard regressions models assessed the association (hazard ratio [HR]) between different expressions of peak V ̇ $$ \dot{\mathrm{V}} $$ O2 with a composite outcome of Fontan failure (FF). Participants were followed up for a median of 6.5 years (95% CI, 6.4-6.9). Individuals experiencing FF (n=10/87) had a significantly lower absolute peak V ̇ $$ \dot{\mathrm{V}} $$ O2. In univariable models, peak V ̇ $$ \dot{\mathrm{V}} $$ O2 ratio scaled to body mass was not significantly associated with FF (HR, 0.91; P=0.111). However, peak V ̇ $$ \dot{\mathrm{V}} $$ O2 scaled by fat-free mass (HR, 0.90; P=0.020) or lean mass (HR, 0.90; P=0.017) was significantly and inversely associated with FF. These associations remained significant after adjusting for age, sex, and peak respiratory exchange ratio.

CONCLUSIONS

The association between peak V ̇ $$ \dot{\mathrm{V}} $$ O2 and FF is improved when scaled to measures of body composition. Applied clinically, a 1-unit increase in peak V ̇ $$ \dot{\mathrm{V}} $$ O2 scaled to fat-free mass or lean mass is associated with a ≈10% lower risk of FF.

Prognostic value of cardiopulmonary exercise test in children with congenital heart defects

BACKGROUND

Cardiopulmonary exercise testing (CPET) has an important prognostic value in adults with different congenital heart defects (CHDs) and is a useful tool for risk stratification and clinical decision-making. In this retrospective study, we studied the prognostic value of CPET in paediatric patients with CHD.

METHODS

411 CPET performed by paediatric patients with different CHDs were evaluated in this retrospective study. Medical records were reviewed to determine the presence of cardiac events. Participants were classified using the 2018 AHA/ACC guideline for the management of adults with CHD that combines anatomical complexity and current physiological stage.

RESULTS

411 patients with a median age at test of 12 years, 51 patients with simple CHD, 170 patients with moderate complexity CHD and 190 with high complexity CHD underwent CPET. Overall, CPET parameters were lower than the reference values (%predicted VO2peak=75% and %predicted oxygen uptake efficiency slope (OUES)=79%), showing worst exercise capacity in the most complex types of CHD (Group III: %predicted VO2peak=72% and %predicted OUES=75%). Seventy-one patients presented with cardiac events at a median time from CPET to first event of 28 months. Patients with cardiac events had lower exercise performance as compared with patients without cardiac events as determined by the submaximal variables (%predicted OUES: HR=2.6 (1.5-4.4), p<0.001 and VE/VCO2: HR=2.2 (1.4-3.5), p=0.001).

CONCLUSION

Reduced exercise capacity at young age is related to a higher probability of future cardiovascular events in paediatric patients with CHD. Submaximal exercise variables can be used instead when maximal exercise cannot be achieved.

Socioeconomic Factors Influencing Pediatric Peak Oxygen Consumption Prediction

OBJECTIVE

To determine if socioeconomic status (SES) has a greater effect than standard demographic values on predicted peak oxygen consumption (pVO2).

STUDY DESIGN

We conducted a single-institution, retrospective analysis of maximal cardiopulmonary exercise test (CPET) data from 2010 to 2020 for healthy patients age <19 years with body mass index (BMI) percentile (BMI%) between 5-95. Data were sorted by self-identified race, BMI%, and adjusted gross income (AGI); AGI served as a surrogate for SES. Mean percent predicted pVO2 (pppVO2) was compared between groups. Linear regression was used to adjust for differences.

RESULTS

A total of 541 CPETs met inclusion criteria. Mean pppVO2 was 97% ± 22.6 predicted (P < .01) with 30% below criterion standard for normal (85% predicted). After excluding unknown AGI and race, 418 CPETs remained. Mean pppVO2 was lower for Blacks (n = 36) and Latinx (n = 26) compared with Whites (n = 333, P < .01). Mean pppVO2 declined as AGI decreased (P < .01). The differences in pppVO2 between racial categories remained significant when adjusted for BMI% (Black r = -7.3, P = .035; Latinx r = -15.4, P < .01). These differences both decreased in magnitude and were no longer significant when adjusted for AGI (Black r = -6.0, P = .150; Latinx r = -9.3, P = .06).

CONCLUSIONS

Lower SES correlates with lower measured cardiovascular fitness and may confound data interpretation. When using normative reference ranges in clinical decision making, providers should recognize that social determinants of health may influence predicted fitness. Social inequities should be considered when assessing pediatric cardiovascular fitness.

Guidance and standard operating procedures for functional exercise testing in cystic fibrosis

Regular exercise testing is recommended for all people with cystic fibrosis (PwCF). A range of validated tests, which integrate both strength and aerobic function, are available and increasingly being used. Together, these tests offer the ability for comprehensive exercise evaluation. Extensive research and expert consensus over recent years has enabled the adaptation and standardisation of a range of exercise tests to aid the understanding of the pathophysiology related to exercise limitation in PwCF and has led to the development of novel exercise tests which may be applied to PwCF. This article provides expert, opinion-based clinical practice guidance, along with test instructions, for a selection of commonly used valid tests which have documented clinimetric properties for PwCF. Importantly, this document also highlights previously used tests that are no longer suggested for PwCF and areas where research is mandated. This collaboration, on behalf of the European Cystic Fibrosis Society Exercise Working Group, represents expert consensus by a multidisciplinary panel of physiotherapists, exercise scientists and clinicians and aims to improve global standardisation of functional exercise testing of PwCF. In short, the standardised use of a small selection of tests performed to a high standard is advocated.

Exercise capacity in the Danish Fontan population remains stable after ten years of follow-up - is physical activity the key to success?

BACKGROUND

Most Fontan patients have impaired exercise capacity, and a further decline in exercise capacity over time seems inevitable. However, few longitudinal studies exist, and there is a lack of data from newer eras. We aimed to describe the natural evolution of exercise capacity over a 10-year period in a contemporary, population-based cohort of Danish Fontan patients.

METHODS

The study was a nationwide, prospective study. A cardiopulmonary exercise test (CPET) was used to assess the exercise capacity. All Danish Fontan patients who participated in a national study in 2011 (CPET1), were invited to a follow-up visit in 2021 (CPET2). All patients who completed CPET1 and CPET2 with a respiratory exchange ratio over 1.0 were included. The main outcome was percent predicted VO2peak (%pred VO2peak). At the time of CPET2, patients filled out a questionnaire including questions regarding physical activity.

RESULTS

Seventy-seven patients completed both CPET1 and CPET2, and seventy patients completed the questionnaire. The time interval between the two CPETs was 10.4 ± 0.9 years. The median age was 15 years at CPET1 and 26 years at CPET2. The exercise capacity remained stable with a mean %pred VO2peak of 53.8 ± 11.3 at CPET1 and 55.6 ± 10.9 in CPET2 (p = 0.314). Higher levels of vigorous physical activity were associated with higher %pred VO2peak in CPET2 in a multivariate regression model.

CONCLUSION

The %pred VO2peak remained stable over a ten-year period in this population-based Fontan cohort. Higher levels of self-reported vigorous physical activity were associated with higher %pred VO2peak in the most recent CPET.

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.

Reference Standards for Cardiorespiratory Fitness in Brazil: A POOLED ANALYSIS AND OVERVIEW OF HETEROGENEITY IN NATIONAL AND INTERNATIONAL STUDIES

PURPOSE

This study aimed to propose reference standards for cardiorespiratory fitness (CRF) for Brazil from a pooled analysis and to compare peak oxygen uptake (V˙ o2peak ) in Brazilian, United States (US), and Norwegian samples, exploring possible national and international differences.

METHODS

Reference values for treadmill V˙ o2peak in three different Brazilian regions were assessed from previous publications. We analyzed available samples to assess possible differences, generate weighted average data for Brazil, and compared them with US and Norwegian data.

RESULTS

Brazilian reference values had a lower V˙ o2peak value for the Northeast region and a higher V˙ o2peak value for the Southeast region for all sex and age groups. International comparisons with the Brazilian pooled data (n = 26661) revealed higher values for the Norwegian sample (n = 3810) and lower values for the US sample (n = 16278). The observed heterogeneity in CRF is possibly related to differences in anthropometric (weight, height) and socioeconomic factors, which differed among the samples. Also, Brazilian data showed a curvilinear V˙ o2peak age reduction trend rather than the linear characteristic commonly utilized, and the regression curves were different from those for US and Norwegian data.

CONCLUSION

This study provides new CRF reference standards for Brazil. After pooling data from three Brazilian regions, a comparison revealed notable differences between regions, evidencing a negative gradient from Southern to Northern regions. Similarly, the international comparisons between Brazil, US, and Norway data revealed CRF heterogeneity, with differences in the V˙ o2peak values and in the age relationship patterns. These findings reinforce the importance of using national- or regional-specific V˙ o2peak reference values, ensuring proper CRF evaluation.

Exercise intervention on cardiorespiratory fitness in rheumatoid arthritis patients with high cardiovascular disease risk: a single-arm pilot study

OBJECTIVE

In patients with rheumatoid arthritis (RA) with cardiovascular disease risk, it is unknown whether exercises are safe, improve cardiorespiratory fitness and reduce disease-related symptoms and cardiovascular-disease (CVD) risk factors. We aimed to investigate in RA patients with CVD risk: (1) safety of medium to high-intensity aerobic exercises, (2) potential changes of cardiorespiratory fitness and (3) disease activity and CVD risk factors in response to the exercises.

METHODS

Single-arm pilot-exercise intervention study including 26 consecutive patients (21 women) with > 4% 10-year risk of CVD mortality according to the Dutch Systematic Coronary Risk Evaluation. Aerobic exercises consisted of two supervised-sessions and five home-sessions per week for 12 weeks. Patients were required to exercise at intensities between 65 and 85% of their maximum heart rate. To assess safety, we recorded exercise related adverse events. Before and after the exercises, cardiorespiratory fitness was assessed with a graded maximal oxygen-uptake exercise test, while disease activity was evaluated via the Disease Activity Score-28 (DAS28) using the erythrocyte segmentation rate (ESR). Resting blood pressure, ESR and total cholesterol were assessed as CVD risk factors.

RESULTS

Twenty out of 26 patients performed the 12-week exercises without any adverse events. According to patients, withdrawals were unrelated to the exercises. Exercises increased cardiorespiratory fitness (pre: 15.91 vs. post: 18.15 ml.kg^-1 min^-1, p = 0.003) and decreased DAS28 (pre: 2.86 vs. post: 2.47, p = 0.04). No changes were detected in CVD risk factors.

CONCLUSION

A 12-week exercise intervention seems to be safe and improves cardiorespiratory fitness and disease activity in patients with RA with a high risk for cardiovascular diseases. Key Points 1. Rheumatoid arthritis patients with high cardiovascular disease risk were able to perform a maximum exercise test and a 12-week aerobic-based medium-to-high intensity exercise intervention. 2. The exercise intervention improved cardiorespiratory fitness and disease activity in rheumatoid arthritis patients with high cardiovascular disease risk. 3. Cardiorespiratory fitness levels were still low post-exercise intervention (i.e. 18.15 ml.kg-1min-1 compared to the 20.9 ml.kg-1min-1 baseline mean of the RA patients without CVD risk).

Cardiorespiratory Fitness and Endothelial Function in Aging Healthy Subjects and Patients With Cardiovascular Disease

Background

Individuals with a higher lifelong cardiorespiratory fitness show better vascular health with aging. Studies on fitness-related effects on endothelial function either analyzed samples with a narrow age-range or incompletely assessed endothelial responsiveness. This study aims to assess the impact of cardiorespiratory fitness on the association of brachial-arterial flow-mediated vasodilation (FMD) and low flow-mediated vasoconstriction (L-FMC) with age in healthy adults and patients with cardiovascular diseases.

Methods

FMD, L-FMC and V.O₂peak were prospectively measured in a population-based sample including 360 healthy adults and 99 patients with cardiovascular disease of European descend. Non-linear models were applied to assess V.O₂peak-associated variations in age-related differences of endothelial function independent of classical cardiovascular risk factors.

Results

FMD was negatively associated with age in healthy adults (adjusted R² = 0.27, partial R² = 0.07, p < 0.001) and in cardiovascular patients (adjusted R² = 0.29, partial R² = 0.05, p = 002). L-FMC showed no association with age. In models predicting the change of FMD with higher age, V.O₂peak accounted for 2.8% of variation in FMD (χ²(5) = 5.37, p = 0.372, s = 1.43). Thereby, V.O₂peak-stratified changes of FMD started to fan out at around 30 years of age in women and 50 years of age in men, with 7–12% lower values at old age with V.O₂peak ≤3rd percentile compared to V.O₂peak ≥97th percentile) in both, the healthy sample and in cardiovascular patients.

Conclusion

The statistical effect of cardiorespiratory fitness on the association of FMD with age independent of classical cardiovascular risk factors was small in both, healthy aging adults as well as patients with cardiovascular diseases. Its clinical significance should be assessed further.

Updated Reference Standards for Cardiorespiratory Fitness Measured with Cardiopulmonary Exercise Testing: Data from the Fitness Registry and the Importance of Exercise National Database (FRIEND)

OBJECTIVE

To provide updated reference standards for cardiorespiratory fitness (CRF) for the United States derived from cardiopulmonary exercise (CPX) testing when using a treadmill or cycle ergometer.

PATIENTS AND METHODS

Thirty-four laboratories in the United States contributed data to the Fitness Registry and the Importance of Exercise National Database. Analysis included 22,379 tests (16,278 treadmill and 6101 cycle ergometer) conducted between January 1, 1968, through March 31, 2021, from apparently healthy adults (aged 20 to 89 years). Percentiles of peak oxygen consumption for men and women were determined for each decade from 20 through 89 years of age for treadmill and cycle exercise modes, as well as when defining maximal effort as respiratory exchange ratio (RER) greater than or equal to 1.0 or RER greater than or equal to 1.1.

RESULTS

For both men and women, the 50^th percentile scores for each exercise mode decreased with age and were higher in men across all age groups and higher for treadmill compared with cycle CPX. The average rate of decline per decade over a 6-decade period was 13.5%, 4.0 mLO₂·kg^-1·min^-1 for treadmill CPX and 16.4%, 4.3 mLO₂·kg^-1·min^-1 for cycle CPX. Observationally, the mean peak oxygen consumption was similar whether using an RER criterion of greater than or equal to 1.0 or greater than or equal to 1.1 across the different test modes, ages, and for both sexes. The updated reference standards for treadmill CPX were 1.5 - 4.6 mLO₂·kg^-1·min^-1 lower compared with the previous 2015 standards whereas the updated cycling standards were generally comparable to the original 2017 standards.

CONCLUSION

These updated cardiorespiratory fitness reference standards improve the representativeness of the US population compared with the original standards.

Health-related physical fitness in patients with complaints of hand, wrist, forearm and elbow: an exploratory study

Objectives

Little is known about the physical fitness of patients with complaints of hand, wrist, forearm and/or elbow and its possible determinants. Aims were to assess health-related physical fitness (HRPF) in these patients, to compare HRPF with reference values of healthy persons, and to explore whether HRPF was correlated with symptom severity, upper limb function (ULF) and physical activity (PA).

Methods

Cardiorespiratory fitness, handgrip strength and body composition, self-reported symptom severity, ULF and PA were assessed in adult outpatients with complaints of hand, wrist, forearm and/or elbow diagnosed as CANS.

Results

Measurements were completed in 25 subjects (8 males) aged 46.1±14.5 years, of which 44% had specific CANS and 56% had non-specific CANS.

Peak oxygen consumption (VO₂peak) of men was 2978±983 mL/min and of women was 1978±265 mL/min. Handgrip strength of men was 47.0±11.1 kgf and of women was 32.4±6.3 kgf. Body mass index (BMI) of men was 24.2±2.6 kg/m² and of women was 27.4±6.1 kg/m².

VO₂peak of the study sample was lower than that of healthy adults (−414±510 mL/min, p<0.001). Handgrip strength and BMI were similar to reference values.

VO₂peak was correlated with PA (r=0.58, p=0.004); BMI was correlated with disability (r=0.48, p=0.022). Other correlations between HRPF and symptom severity and ULF were non-significant.

Conclusions

Patients with CANS have lower cardiorespiratory fitness, but similar handgrip strength and body composition, compared with the healthy population. Cardiorespiratory fitness was correlated with PA and BMI was correlated with disability, no other correlations were observed with symptom severity and ULF.

Determinants of exercise limitation in contemporary paediatric Fontan patients with an extra cardiac conduit

BACKGROUND

Although various determinants of exercise limitation in Fontan patients have been studied, most research has been performed in patients who underwent different surgical procedures with differing haemodynamic characteristics. The aim of the current study was to evaluate non-invasively measured cardiovascular parameters and their influence on exercise performance in paediatric Fontan patients with an extracardiac conduit and moderate-good systolic ventricular function.

METHODS

Fontan patients, between 8 and 18 years of age, with moderate to good systolic ventricular function and an extracardiac conduit were included. Exercise performance and cardiovascular assessment, comprising echocardiography, aortic stiffness measurement and ambulatory measurement of cardiac autonomous nervous activity were performed on the same day. Healthy subjects served as controls.

RESULTS

Thirty-six Fontan patients (age 14.0 years) and thirty-five healthy subjects (age 12.8 years) were included. Compared to controls, Fontan patients had reduced diastolic ventricular function and increased arterial stiffness. No differences were found in heart rate (HR) and cardiac parasympathetic nervous activity. In Fontan patients, maximal as well as submaximal exercise capacity was impaired, with the percentage of predicted capacity ranging between 54 and 72%. Chronotropic competence, however, was good with a peak HR of 174 (94% of predicted). Lower maximal and submaximal exercise capacity was correlated with a higher HR at rest, higher pulse wave velocity of the aorta and a lower ratio of early and late diastolic flow velocity.

CONCLUSION

Contemporary paediatric Fontan patients have an impaired exercise capacity with preserved chronotropic competence. Exercise performance correlates with heart rate at rest, diastolic function and aortic stiffness.

Cardiorespiratory fitness and physical activity in people who have rheumatoid arthritis at an increased risk of cardiovascular disease: a cross-sectional study

Lower cardiorespiratory fitness (CRF) and physical activity (PA) associate with higher cardiovascular disease (CVD) risk, but the relationship between CRF and PA in people who have rheumatoid arthritis (RA) at an increased CVD risk (CVD-RA) is not known. The objectives of this study were to determine the levels of CRF and PA in people who have CVD-RA and to investigate the association of CRF with PA in people who have CVD-RA. A total of 24 consecutive patients (19 women) with CVD-RA (> 4% for 10-year risk of fatal CVD development as calculated using the Systematic Coronary Risk Evaluation)-were included in the study. CRF was assessed with a graded maximal exercise test determining maximal oxygen uptake (VO_2max). PA was assessed with an accelerometer to determine the amount of step count, sedentary, light and moderate-to-vigorous physical activity (MVPA) minutes per day. Mean age of patients was 65.3 ± 8.3 years. CRF mean values were 16.3 ± 1.2 ml·kg^-1 min^-1, mean step count per day was 6033 ± 2256, and the mean MVPA time was 16.7 min per day. Significant positive associations were found for CRF with step count (B = 0.001, P = 0.01) and MVPA time (B = 0.15, P = 0.02); a negative association was found for CRF with sedentary time (B =  - 0.02, P = 0.03). CRF is low and is associated with step count, sedentary time and MVPA time in people who have RA at an increased CVD risk.

Cardiodynamic variables measured by impedance cardiography during a 6-minute walk test are reliable predictors of peak oxygen consumption in young healthy adults

Accurate prediction of aerobic capacity is necessary to guide appropriate exercise prescription. It is common to use 6-minute walk distance (6MWD) to predict peak oxygen uptake (VO2peak) in the clinical environment. The aim of this study was to determine whether prediction of VO2peak can be improved by the inclusion of cardiovascular indices derived by impedance cardiography (ICG) during the 6MWT. A total of 62 healthy university students aged 21±1 years completed in separate days, a cardiopulmonary exercise test (CPET) and two 6MWTs (30 min apart), during which heart rate (HR), stroke volume (SV) and cardiac output (CO) were measured by ICG (PhysioFlow® PF07 EnduroTM). The CPET was conducted with the Ergoselect 200 Ergoline and oxygen consumption measured by a MasterScreenTM CPX breath-by-breath metabolic cart. Multiple regression analyses were conducted to generate VO2peak prediction equations using 6MWD with, or without the cardiovascular indices recorded at the end of the best performed 6MWT as predictor variables. The mean peak HR (bpm), SV (ml) and CO (L/min) recorded during 6MWT were 156±18, 95.6±9, 15±2.8 and during CPET were 176±16, 91.3±8, 16.2±2.7, respectively. Analyses revealed the following VO2peak prediction equation: VO2peak = 100.297+(0.019x6MWD)+(-0.598xHR6MWT)+(-1.236xSV6MWT) + (8.671 x CO6MWT). This equation has a squared multiple correlation (R2) of 0.866, standard error of the estimate (SEE) of 2.28 mL/kg/min and SEE:VO2peak (SEE%) of 7.2%. Cross-validation of equation stability using predicted residual sum of squares (PRESS) statistics showed a R2 (Rp2), SEE (SEEp) and SEEp% of 0.842, 2.38 mL/kg/min and 7.6% respectively. The minimal shrinkage of R2 implied regression model stability. Correlation between measured and predicted VO2peak using this equation was strong (r = 0.931, p<0.001). When 6MWD alone was used as the predictor for VO2peak, the generated equation had a lower R2 (0.549), and a higher SEE (4.08 mL/kg/min) and SEE% (12.9%). This is the first study which included cardiac indices during a 6MWT as variables for VO2peak prediction. Our results suggest that inclusion of cardiac indices measured during the 6MWT more accurately predicts VO2peak than using 6MWD data alone.

Exercise capacity in patients with repaired Tetralogy of Fallot aged 6 to 63 years

OBJECTIVES

This study aimed to provide a perspective for the interpretation of exercise capacity (peakVO₂) in patients with repaired Tetralogy of Fallot (patients with rTOF) by describing the course of peakVO₂ from patients aged 6-63 years.

METHODS

A retrospective study was performed between September 2001 and December 2016 in the German Heart Centre Munich, Germany, and in the University Medical Centre Groningen, the Netherlands. A total of 1175 cardiopulmonary exercise tests (CPETs) were collected from 586 patients with rTOF, 46% female. Maximal exertion was verified using a respiratory exchange ratio ≥1.00. PeakVO₂ was modelled using time-dependent multilevel models for repeated measurements (n=889 in 300 patients), and compared with subject-specific reference values calculated by the models of Bongers et al and Mylius et al. RESULTS: The peakVO₂ of patients with rTOF was reduced at all ages. At the age of 6, the peakVO₂ was 614 mL/min (70% of predicted (95% CI 67 to 73)). The reduced increase in peakVO₂ during adolescence resulted in a significant lower maximum peakVO₂ of 1209 mL/min at 25 years (65% predicted, p<0.001). A linear decline after 25 years was observed in patients and references, although patients showed an accelerated decline, with a -0.24% point of predicted (95% CI 0.11 to 0.38) per year without differences between sexes (p=0.263).

CONCLUSIONS

This study provides a context for peakVO₂ across ages in patients with rTOF under contemporary treatment strategies. It showed that the reduction in peakVO₂ originates from childhood and declines over time. Sex differences in patients with rTOF were similar to natural existing sex differences.

A 10-year follow-up of key gas exchange exercise parameters in a general population: results of the Study of Health in Pomerania

Background

Cardiopulmonary exercise testing (CPET) is a frequently used method for the evaluation of the cardiorespiratory system. The prognostic relevance of the measured parameters is commonly known. Longitudinal data on cardiorespiratory fitness in a large sample of well-characterised healthy volunteers are rare in the literature.

Methods

CPET data of 615 healthy individuals who voluntarily took part in the Study of Health in Pomerania (SHIP) at three different measurement times were analysed. The median observation time was 10.5 years. The age range was 25–85 years.

Results

Over the observed timeframe and with increasing age, a decline in maximum power, peak oxygen uptake (V′_O2peak) and oxygen uptake at anaerobic threshold (V′_O2@AT) was detectable. This decline was aggravated with increasing age. For the minute ventilation (V′_E)/carbon dioxide production (V′_CO2) slope, an increase was measured in individuals aged ≥50 years only.

Conclusion

The present study affirms the decrease in aerobic capacity with increasing age in a selected, well-characterised, healthy study sample, which seems to be less pronounced in females.

A 10-year follow-up of the Study of Health in Pomerania affirms the decrease in aerobic capacity with increasing age in a selected, well-characterised, healthy study sample, which seems to be less pronounced in femaleshttps://bit.ly/3pIJmpM

Reference values for maximum oxygen uptake relative to body mass in Dutch/Flemish subjects aged 6-65 years: the LowLands Fitness Registry

Background

The maximum oxygen uptake (VO₂max) during cardiopulmonary exercise testing (CPET) is considered the best measure of cardiorespiratory fitness.

Aim

To provide up-to-date reference values for the VO₂max per kilogram of body mass (VO₂max/kg) obtained by CPET in the Netherlands and Flanders.

Methods

The Lowlands Fitness Registry contains data from health checks among different professions and was used for this study. Data from 4612 apparently healthy subjects, 3671 males and 941 females, who performed maximum effort during cycle ergometry were analysed. Reference values for the VO₂max/kg and corresponding centile curves were created according to the LMS method.

Results

Age had a negative significant effect (p < .001) and males had higher values of VO₂max/kg with an overall difference of 18.0% compared to females.

Formulas for reference values were developed:

Males: VO₂max/kg = − 0.0049 × age² + 0.0884 × age + 48.263 (R² = 0.9859; SEE = 1.4364)

Females: VO₂max/kg = − 0.0021 × age² − 0.1407 × age + 43.066 (R² = 0.9989; SEE = 0.5775).

Cross-validation showed no relevant statistical mean difference between measured and predicted values for males and a small but significant mean difference for females. We found remarkable higher VO₂max/kg values compared to previously published studies.

Conclusions

This is the first study to provide reference values for the VO₂max/kg based on a Dutch/Flemish cohort. Our reference values can be used for a more accurate interpretation of the VO₂max in the West-European population.

Oxygen Uptake Efficiency Slope is Strongly Correlated to VO2peak Long-Term After Arterial Switch Operation

After the arterial switch operation (ASO) for transposition of the great arteries (TGA), many patients have an impaired exercise tolerance. Exercise tolerance is determined with cardiopulmonary exercise testing by peak oxygen uptake (VO_2peak). Unlike VO_2peak, the oxygen uptake efficiency slope (OUES) does not require a maximal effort for interpretation. The value of OUES has not been assessed in a large group of patients after ASO. The purpose of this study was to determine OUES and VO_2peak, evaluate its interrelationship and assess whether exercise tolerance is related to ventricular function after ASO. A cardiopulmonary exercise testing, assessment of physical activity score and transthoracic echocardiography (fractional shortening and left/right ventricular global longitudinal peak strain) were performed to 48 patients after ASO. Median age at follow-up after ASO was 16.0 (IQR 13.0-18.0) years. Shortening fraction was normal (36 ± 6%). Left and right global longitudinal peak strain were reduced: 15.1 ± 2.4% and 19.5 ± 4.5%. This group of patients showed lower values for all cardiopulmonary exercise testing parameters compared to the reference values: mean VO_2peak% 75% (95% CI 72-77) and mean OUES% 82(95% CI 77-87); without significant differences between subtypes of TGA. A strong-to-excellent correlation between the VO_2peak and OUES was found (absolute values: R = 0.90, p < 0.001; normalized values: R = 0.79, p < 0.001). No correlation was found between cardiopulmonary exercise testing results and left ventricle function parameters. In conclusion, OUES and VO_2peak were lower in patients after ASO compared to reference values but are strongly correlated, making OUES a valuable tool to use in this patient group when maximal effort is not achievable.

Normative Peak Cardiopulmonary Exercise Test Responses in Canadian Adults Aged ≥40 Years

BACKGROUND

Up-to-date normative reference sets for cardiopulmonary exercise testing (CPET) are important to aid in the accurate interpretation of CPET in clinical or research settings.

RESEARCH QUESTION

This study aimed to (1) develop and externally validate a contemporary reference set for peak CPET responses in Canadian adults identified with population-based sampling; and (2) evaluate previously recommended reference equations for predicting peak CPET responses.

STUDY DESIGN AND METHODS

Participants were healthy adults who were ≥40 years old from the Canadian Cohort Obstructive Lung Disease who completed an incremental cycle CPET. Prediction models for peak CPET responses were estimated from readily available participant characteristics (age, sex, height, body mass) with the use of quantile regression. External validation was performed with a second convenience sample of healthy adults. Peak CPET parameters that were measured and predicted in the validation cohort were assessed for equivalence (two one-sided tests of equivalence for paired-samples and level of agreement (Bland-Altman analyses). Two one-sided tests of equivalence for paired samples assessed differences between responses in the derivation cohort using previously recommended reference equations.

RESULTS

Normative reference ranges (5th-95th percentiles) for 28 peak CPET parameters and prediction models for 8 peak CPET parameters were based on 173 participants (47% male) who were 64 ± 10 years old. In the validation cohort (n = 84), peak CPET responses that were predicted with the newly generated models were equivalent to the measured values. Peak cardiac parameters predicted by the previously recommended reference equations by Jones and colleagues and Hansen and colleagues were significantly higher.

INTERPRETATION

This study provides reference ranges and prediction models for peak cardiac, ventilatory, operating lung volume, gas exchange, and symptom responses to incremental CPET and presents the most comprehensive reference set to date in Canadian adults who were ≥40 years old to be identified with population-based sampling.

Long-term effects of ivacaftor on nonpulmonary outcomes in individuals with cystic fibrosis, heterozygous for a S1251N mutation

OBJECTIVES

To describe the long-term effects of ivacaftor (Kalydeco®) in individuals with cystic fibrosis (CF) on body mass index (BMI), body composition (BC), pulmonary function (PF), resting energy expenditure (REE), and exercise capacity (EC) after ≥12 months of treatment.

WORKING HYPOTHESIS

BMI, lean and fat mass, PF, and EC will increase and REE will decrease after treatment.

STUDY DESIGN

Observational study.

METHODOLOGY

Seven individuals with CF (mean age 15.4 ± 5.8 years) heterozygous for S1251N mutation, starting with ivacaftor, were included. Paired t tests were performed to assess the effects of ivacaftor. Height and weight were used to calculate BMI and BMI Z-scores. Dual-energy X-ray absorptiometry was used to assess BC. Spirometry and body plethysmography were used to assess PF. Indirect calorimetry was used to measure REE and cardiopulmonary exercise testing (CPET) was used to measure oxygen uptake (VO_2peak ), peak work rate (W_peak ), and other CPET variables.

RESULTS

After a median of 15 (interquartile range: 13-16) months of treatment, BMI increased significantly (P = .03), but not BMI Z-score (P = .23) or BC. Significant improvements were found for several PF variables, especially measures of hyperinflation (P = .02). Absolute VO_2peak (P = .01), VO_2peak related to body weight (P = .00), and oxygen cost of work (P = .01) decreased. Absolute W_peak (P = .59) and W_peak related to body weight (P = .31) remained stable.

CONCLUSIONS

The results showed that long-term treatment of ivacaftor is associated with improvement of BMI and PF, but not of BC and REE. Oxygen uptake reduced after treatment, which may be due to a decrease in work of breathing.

GDF-15 (Growth Differentiation Factor 15) Is Associated With Hospitalization and Mortality in Patients With a Fontan Circulation

Background We investigated serial serum levels of GDF-15 (growth differentiation factor 15) in Fontan patients and their relation to outcome. Methods and Results In this single-center prospective study of consecutive Fontan patients, serial serum GDF-15 measurement and clinical assessment was done at baseline (n=81) and after 2 years (n=51). The association between GDF-15 and the combined end point of all-cause mortality, heart transplant listing, and Fontan-related hospitalization was investigated. Median age at baseline was 21 years (interquartile range: 15-28 years). Median GDF-15 serum levels at baseline were 552 pg/mL (interquartile range: 453-729 pg/mL). GDF-15 serum levels correlated positively with age, age at Fontan initiation, New York Heart Association class, and serum levels of NT-proBNP (N-terminal pro-B-type natriuretic peptide) and ɣGT (γ-glutamyltransferase) and negatively with exercise capacity. During a median follow-up of 4.8 years (interquartile range: 3.3-5.5 years), the combined end point occurred in 30 patients (37%). Multivariate Cox regression showed that patients with the highest baseline GDF-15 (n=20, defined as the upper quartile) had a higher risk of hospitalization or death than the lowest 3 quartiles (hazard ratio [HR], 2.76; 95% CI, 1.27-6.00; P=0.011). After 2 years of follow-up, patients in whom serum level of GDF-15 increased to >70 pg/mL (n=13) had a higher risk of hospitalization or death than the lowest 3 quartiles (HR, 2.69; 95% CI, 1.03-6.99; P=0.043). Conclusions In Fontan patients, elevated serum levels of GDF-15 are associated with worse functional status and predict Fontan-related events. Furthermore, serial measurements showed that an increase in GDF-15 serum level was associated with increased risk for adverse outcome.