Oxygen Uptake Efficiency Slope Research Articles

Usefulness of oxygen uptake efficiency slope in a 6min walk test in chronic heart failure.

Frailty is an obstacle to performing cardiopulmonary exercise test (CPET) in patients with chronic heart failure (CHF). We evaluated the usefulness of oxygen uptake efficiency slope (OUES) using a 6min walk test (6MWT) with portable gas analysis compared with CPET-derived parameters in patients with CHF. Patients with CHF who underwent both the 6MWT with portable gas analysis and CPET between December 2016 and May 2020 were retrospectively investigated. The 6MWT-derived and echocardiographic parameters were compared with the OUES and peak oxygen consumption (VO2) from the CPET. Forty patients were analysed; 50% were male with a mean age of 55.45±14.70years. Twenty-six patients (65%) had New York Heart Association Functional Classification II or III dyspnoea. Twenty-five patients (62.5%) had heart failure (HF) with preserved ejection fraction (EF) (left ventricular EF>50%), and nine patients (22.5%) had HF with reduced EF (EF<40%). During the 6MWT, the peak VO2 was 14.97±3.80mL/kg/min, which was only 74% of the peak VO2 in the CPET, 20.18±5.64mL/kg/min. The OUES in the 6MWT was lower than that in the CPET (1528.87±579.01 in the 6MWT vs. 1638.69±601.31 in the CPET). The 6min walk distance (6MWD) and OUES in the 6MWT were positively correlated with the OUES in the CPET (6MWD, r=0.434, P=0.005; OUES, r=0.729, P<0.001). The OUES in the 6MWT showed the strongest correlation with the OUES in the CPET. When we divided patients into two groups according to peak VO2 in the CPET, the correlation between OUES values of the 6MWT and that of the CPET was consistently confirmed (peak VO2≥20mL/kg/min group, r=0.661, P=0.001; peak VO2<20mL/kg/min group, r=0.526, P=0.021). In addition, the 6MWD, OUES, and peak VO2 in the 6MWT were associated with peak VO2 in the CPET (6MWD, r=0.627, P<0.001; OUES, r=0.452, P=0.003; and peak VO2, r=0.492, P=0.001). In frail patients with CHF who have difficulty performing maximal exercises, the OUES through the 6MWT may be applied instead of the OUES and peak VO2 from the CPET.

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

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

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

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. 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. 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. 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.

Effects of Exercise Training Response on Quality of Life and Cardiovascular Risk Factor Profiles in People With Coronary Artery Disease: Insights From the HIIT or MISS UK Trial

ObjectiveTo compare the characteristics of responders and nonresponders to 8 weeks of exercise training to determine differences in key cardiovascular disease outcomes in people with coronary artery disease (CAD). DesignSecondary analysis of data from the HIIT or MISS UK trial. SettingSix outpatient National Health Service cardiac rehabilitation (CR) centers in the UK. In people with CAD attending CR, the HIIT or MISS UK trial reported that short-term, low-volume, high-intensity interval training (HIIT) was more effective than moderate-intensity steady state (MISS) exercise training for improving peak oxygen uptake (V̇o2peak). Participants382 participants with CAD (N=382) (mean age: 58.8±9.6y; mean body mass index: 29.0±4.3 kg/m2). Main Outcome MeasuresWe identified responders and nonresponders based on a meaningful change in V̇o2peak, using 2 established methods. Key clinical, quality of life (QoL), and cardiopulmonary exercise test (CPET)–derived outcomes were compared between groups. ResultsResponders were more likely to be younger (P<.05), and demonstrate greater improvement in CPET-related outcomes, for example, oxygen uptake efficiency slope, ventilatory efficiency, and peak power output (all comparisons, P<.001). Responders were more likely to observe improvements in QoL (EQ-5D-5L; mean Δ 13.6 vs mean Δ 9.4; P=.045), and high-density lipoprotein cholesterol (HDL-c) (mean Δ 0.09 mmol/L vs mean Δ 0.04 mmol/L; P=.004), compared to nonresponders. ConclusionsIn people with CAD attending CR, responders to exercise training were more likely to be younger and demonstrate greater improvements in health-related QoL and HDL-c.

Cardiopulmonary Exercise Testing after Surgical Repair of Tetralogy of Fallot-Does Modality Matter?

Despite a successful repair of tetralogy of Fallot (rToF) in childhood, residual lesions are common and can contribute to impaired exercise capacity. Although both cycle ergometer and treadmill protocols are often used interchangeably these approaches have not been directly compared. In this study we examined cardiopulmonary exercise test (CPET) measurements in rToF. Inclusion criteria were clinically stable rToF patients able to perform a cardiac magnetic resonance imaging (CMR) and two CPET studies, one on the treadmill (incremental Bruce protocol) and one on the cycle ergometer (ramped protocol), within 12 months. Demographic, surgical and clinical data; functional class; QRS duration; CMR measures; CPET data and international physical activity questionnaire (IPAQ) scores of patients were collected. Fifty-seven patients were enrolled (53% male, 20.5 ± 7.8 years at CPET). CMR measurements included a right ventricle (RV) end-diastolic volume index of 119 ± 22 mL/m2, a RV ejection fraction (EF) of 55 ± 6% and a left ventricular (LV) EF of 56 ± 5%. Peak oxygen consumption (VO2)/Kg (25.5 ± 5.5 vs. 31.7 ± 6.9; p < 0.0001), VO2 at anaerobic threshold (AT) (15.3 ± 3.9 vs. 22.0 ± 4.5; p < 0.0001), peak O2 pulse (10.6 ± 3.0 vs. 12.1± 3.4; p = 0.0061) and oxygen uptake efficiency slope (OUES) (1932.2 ± 623.6 vs. 2292.0 ± 639.4; p < 0.001) were significantly lower on the cycle ergometer compared with the treadmill, differently from ventilatory efficiency (VE/VCO2) max which was significantly higher on the cycle ergometer (32.2 ± 4.5 vs. 30.4 ± 5.4; p < 0.001). Only the VE/VCO2 slope at the respiratory compensation point (RCP) was similar between the two methodologies (p = 0.150). The majority of CPET measurements differed according to the modality of testing, with the exception being the VE/VCO2 slope at RCP. Our data suggest that CPET parameters should be interpreted according to test type; however, these findings should be validated in larger populations and in a variety of institutions.

Mechanisms underlying exercise intolerance in long COVID: An accumulation of multisystem dysfunction.

The pathogenesis of exercise intolerance and persistent fatigue which can follow an infection with the SARS-CoV-2 virus ("long COVID") is not fully understood. Cases were recruited from a long COVID clinic (N = 32; 44 ± 12 years; 10 (31%) men), and age-/sex-matched healthy controls (HC) (N = 19; 40 ± 13 years; 6 (32%) men) from University College London staff and students. We assessed exercise performance, lung and cardiac function, vascular health, skeletal muscle oxidative capacity, and autonomic nervous system (ANS) function. Key outcome measures for each physiological system were compared between groups using potential outcome means (95% confidence intervals) adjusted for potential confounders. Long COVID participant outcomes were compared to normative values. When compared to HC, cases exhibited reduced oxygen uptake efficiency slope (1847 (1679, 2016) vs. 2176 (1978, 2373) mL/min, p = 0.002) and anaerobic threshold (13.2 (12.2, 14.3) vs. 15.6 (14.4, 17.2) mL/kg/min, p < 0.001), and lower oxidative capacity, measured using near infrared spectroscopy (τ: 38.7 (31.9, 45.6) vs. 24.6 (19.1, 30.1) s, p = 0.001). In cases, ANS measures fell below normal limits in 39%. Long COVID is associated with reduced measures of exercise performance and skeletal muscle oxidative capacity in the absence of evidence of microvascular dysfunction, suggesting mitochondrial pathology. There was evidence of attendant ANS dysregulation in a significant proportion. These multisystem factors might contribute to impaired exercise tolerance in long COVID sufferers.

Below or all the way to the peak? Oxygen uptake efficiency slope as the index of cardiorespiratory response to exercise-the NOODLE study.

Background: The ratio of oxygen uptake (VO2) to minute ventilation (VE) is described as the oxygen uptake efficiency slope (OUES). OUES has been suggested as a valuable submaximal cardiorespiratory index; however, its characteristics in endurance athletes remain unknown. In this study, we a) investigated OUES between different time intervals, b) assessed their prediction power for VO2peak, and c) derived new prediction equations for OUES tailored for well-trained individuals. Materials and Methods: A total of 77 male (age = 21.4 ± 4.8yrs; BMI = 22.1 ± 1.6kg·m-2; peak oxygen uptake = 4.40 ± 0.64L·min-1) and 63 female individuals (age = 23.4 ± 4.3yrs; BMI = 23.1 ± 1.6kg·m-2; peak oxygen uptake = 3.21 ± 0.48L·min-1) underwent the cycling cardiopulmonary exercise test. OUES was measured at 75%, 90%, and 100% of exercise duration. Prediction power and new models were derived with the multiple linear regression method. Results: In male subjects, OUES [mL·min-1/L·min-1] from 75% = 4.53 ± 0.90, from 90% = 4.52 ± 0.91, and from 100% = 4.41 ± 0.87. In female subjects, OUES [mL·min-1/L·min-1] from 75% = 3.50 ± 0.65, from 90% = 3.49 ± 0.62, and from 100% = 3.41 ± 0.58. OUES did not differ between time intervals in male (p = 0.65) and female individuals (p = 0.69). OUES strongly predicts peak VO2 independently from the measuring interval (β = 0.71-0.80; R 2 = 0.50-0.63). The prediction model designed for elite athletes was OUES [mL·min-1/L·min-1] = -1.54 + 2.99; BSA [m2]-0.0014; (age [in years]; sex [1 = male, 2 = female]) (R 2 = 0.36). Conclusion: OUES enables an accurate prediction of peak cardiorespiratory fitness in elite endurance athletes. OUES is a feasible alternative to maximal exercise testing. A new prediction equation should be used for highly trained individuals. Physicians should understand OUES physiology to properly assess the cardiorespiratory response to exercise in athletic cohorts.

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.

ALTERAÇÕES DA VE/VCO2 E OUES DURANTE EXERCÍCIO PROGRESSIVO EM PACIENTES COM INSUFICIÊNCIA CARDÍACA

Introduction: Heart failure originates from several etiologies resulting in cardiorespiratory impairment during physical effort. Objective: To compare the behavior of cardiorespiratory variables, slope of oxygen uptake efficiency slope and the relationship between pulmonary ventilation and carbon dioxide production between individuals with heart failure and healthy individuals. Methods: 61 male individuals (61.2 ± 7.8 years) were evaluated, who were separated into two groups: Group CI - Patients with Cardiac Insufficiency (n = 40) and Group C - Control (n = 21). The volunteers performed assessments of the following parameters: age, height, body mass and body mass index. The ergospirometry test was also performed, consisting of performing a graded exercise testing on a treadmill with direct analysis of the respiratory gases: VE/VCO2, VO2peak, PetCO2, OUES and the hemodynamic variables: maximum heart rate, recovery heart rate after the 1st minute and the echocardiogram. The Kolmorovsminoff test for normality was performed, the data were expressed as mean and standard error and the inferential analysis performed with the Anova and Post-Hoc Tests of Scheffé, considering p≤0.05. Results: The anthropometric, hemodynamic and respiratory variables results for the CI and C groups, respectively, were: age =61,0±8,2 vs. 61,5±7,4 years (p&gt;0,05), height= 1,72±5,8 vs. 1,72±6,8m (p&gt;0,05), body mass = 77,3±9,9 vs. 78,3±9,0kg (p&gt;0,05), IMC = 26,5±3,0 vs. 26,2±2,8 kg/m2 (p&gt;0,05), ejection fraction = 31,2±4,1 vs. 64,7±3,9mL (p&lt;0,001), maximum cardio frequency = 128,6±22,9 vs. 143,6±15,5bpm (p&lt;0,02), recovery heart rate after the 1st minute = -17,4±5,4 vs. -25,0±4,9bpm (p&lt;0,05), VE/VCO2slope = 38,8±5,6 vs. 28,2±3,9L/min (p&lt;0,003), VO2peak = 20,0±4,0 vs. 36,7±5,5ml/kg/min (p&lt;0,05), PetCO2 = 29,5±3,0 vs. 31,7±2,4mmHg (p&lt;0,05) and OUES = 1,81±0,4 vs. 2,3±0,3 (p&lt;0,05). Conclusion: Patients with heart failure showed high values of VE/VCO2 and low values of OUES, which limits functional capacity and leads to the early onset of metabolic acidosis. Level of Evidence I; High-Quality Prospective Study.

Periodized Aerobic Training between Thresholds Improves Submaximal Cardiorespiratory Parameters in Octogenarians.

The worldwide aging population is expanding, with more individuals living into their 80s. Physiological functions decline gradually with age, compounded by sedentary lifestyles. Incorporating physical activity into daily routine is crucial for maintaining independence. This study aimed to assess a periodized high-intensity aerobic training program (PEZO-BT) in octogenarians, focusing on submaximal ergospirometry effects. A total of 48 non-frail octogenarian subjects (12 females, 36 males) were randomized into control and intervention groups. All subjects underwent submaximal cardiopulmonary exercise testing with gas analysis at baseline, stopping after the respiratory compensation point (RCP). Our intervention group completed a 14-week PEZO-BT aerobic training program. The outcomes were oxygen consumption at first ventilatory threshold (VO2AT), ventilatory efficiency slope (VE/VCO2), oxygen uptake efficiency slope (OUES), cardiorespiratory optimal point (COP), oxygen pulse change (ΔVO2/HR) from anaerobic threshold (AT) to respiratory compensation point (RCP), and power output at anaerobic threshold (POAT). Mixed ANOVA examined time and treatment effects. If significance emerged, post hoc t-tests were used to compare significances between groups. The homogeneity of variance was assessed using Levene's test. Chi-square tests compared ergospirometry criteria and ventilatory performance within groups. The mean differences at post intervention were significant in VO2AT (p < 0.001), VE/VCO2 (p < 0.001), ΔVO2/HR (p < 0.05), and POAT (p < 0.001), while OUES and COP were not significant (p > 0.05). However, clinical effects were observed in the entire intervention group. Training improved exercise capacity and workload. Overall, this periodic aerobic and high-intensity interval training (HIIT) program yielded significant improvements in cardiorespiratory fitness (CRF) in previously untrained octogenarians with and without comorbidities. The findings suggest implications for promoting long-term healthy aging.

Abstract 13452: Clinical Usefulness of Oxygen Uptake Efficiency Slope for Evaluation Functional Capacity of Heart Failure With Preserved Ejection Fraction

1. Backgrand: The diagnostic criteria for HFpEF have been established; however, the evaluation criteria for functional capacity, such as LVEF in HFrEF, have not been clearly delineated. Furthermore, exercise intolerance is a prominent manifestation in patients with HFpEF.Considering these factors, the objective of this study was to analyze the results of cardiopulmonary exercise testing (CPET) in the HFpEF patient cohort and utilize them for the assessment of functional capacity. 2. Methods: Exercise echocardiographic data were retrospectively analyzed in a cohort of 83 patients who underwent exercise echocardiography between September 2021 and October 2022. Among them, 64 patients also underwent cardiopulmonary exercise testing (CPET). The diagnostic criteria for HFpEF were determined based on the ASE/EACVI algorithm, as outlined below. 3. Result: Notably, only in the case of the oxygen uptake efficiency slope (OUES), the patient group with diastolic dysfunction displayed a statistically significant result that was significantly lower than that of the group with normal diastolic function. Based on these findings, when the ROC curve was generated using OUES as the negative predictive value, the AUC was 0.708, indicating a fair result. 4. Conclusions: The decrease in OUES was found to be statistically significant in HFpEF patients. As a result, it is anticipated that OUES can serve as a measure for evaluating functional capacity in HFpEF patients, in addition to serving as an objective indicator of improved cardiopulmonary exercise capacity when treating HFpEF patients.

Abstract 13995: Remote, Smart Device Based Cardiac Rehabilitation After Myocardial Infarction - Smart Rehab Study

Introduction: After myocardial infarction (MI), increasing functional capacity is an important goal of cardiac rehabilitation, that improves prognosis. However, standard cardiac rehabilitation is not accessible to many patients. Telemedicine programs are emerging as promising alternatives to in-person programs, but evidence confirming its benefits is lacking. Hypothesis: Smart device based remote cardiac rehabilitation can improve functional capacity assessed by VO2peak after MI. Methods: Patients were offered participation at the time of hospitalization for MI. One month after MI, patients underwent a cardiopulmonary exercise test, 6-minute walking test (6MWT) and were randomized 1:1. In the intervention group, patients received a smart watch to track the recommended number of steps, that was derived from the 6MWT. Adherence to the recommendations was telemonitored by a study nurse, with an over the phone motivation talk if compliance was unsatisfactory. In the control group, patients were recommended 150 minutes/week of moderate intensity exercise. Exercise stress tests were repeated after 3 months. Results: In total, 59 patients (mean age 51.5±10.4 years, 10.2% women, 67.8% STEMI, 96.6% PCI, mean discharge EF 48±10%) were included in the study. At baseline, there was no difference in clinical characteristics and functional capacity between the intervention (n=29) and control (n=30) groups. After 3 months of the intervention, VO2peak improved in the intervention arm with between group difference of 1.56 ml/kg/min (95%CI 0.06-3.05, p=0.041), with no difference in 6-minute walking distance (p=0.11). The effect of intervention differed by baseline functional capacity (p for interaction &lt;0.01). Among patients with VO2peak at baseline ≤95% predicted, the between-group VO2peak difference after 3 months was 2.46 ml/kg/min (95% CI 0.78-4.13, p=0.005), and also oxygen uptake efficiency slope (between group difference 235, 95% CI 43-428, p=0.02) and 6-minute walking distance improved (between group difference 60m, 95% CI 1.5-119, p=0.045). Conclusions: Smart device based remote cardiac rehabilitation improves functional capacity after myocardial infarction, particularly in those with decreased functional capacity. NCT03926312

Abstract 12910: Exercise Hemodynamics Unmasks Stage C Heart Failure With Preserved Ejection Fraction and Impaired Peripheral Oxygen Extraction in Stage A/B Patients in a Safety-Net Center

Introduction: There is a gap in research evaluating hemodynamics and impaired peripheral oxygen extraction in Stage A/B HFpEF in diverse groups. We sought to characterize the prevalence of impaired cardiac/peripheral profiles in Stage A/B HFpEF at Boston Medical Center. Hypothesis: We hypothesize both abnormal cardiac and peripheral profiles will be unmasked in exercising Stage A/B HFpEF patients. Methods: Invasive cardiopulmonary exercise testing (iCPET) was performed in 30 individuals with Stage A/B HFpEF. Significant valvular or pulmonary disease were excluded. Criteria for an impaired cardiac profile, with reclassification to Stage C, included exercise PCWP ≥ 25 mmHg or ΔPCWP/ΔCO slope &gt; 2 mmHg/L/min. An impaired peripheral profile was defined as O 2 extraction ratio (peak arterio-venous oxygen saturation difference)/ (1.34*rest hemoglobin*rest arterial O 2 saturation) &lt; 50%. With an approved IRB, the analysis was conducted in R. Results: Cohort clinical data shown in Table with 47% non-white and 57% female patients. Exercise unmasked Stage C HFpEF in 23 (77%) of cases; 17% had an impaired peripheral profile (O 2 extraction ratio 43 ± 7) and 10% (3 out of 30 patients) had concomitant impaired cardiac and peripheral profiles. Both cardiac and peripheral metrics correlated to metabolic parameters: peak oxygen consumption correlated to PCWP (rho -0.52, p&lt;0.004) and extraction ratio correlated to oxygen-uptake efficiency slope (rho 0.40, p=0.029). Conclusions: In our diverse cohort, a significant proportion of Stage A/B patients reclassified to Stage C HFpEF via invasive exercise testing; abnormal peripheral profiles were also noted. Impaired cardiac and peripheral profile metrics were related to metabolic parameters. Broader implementation of iCPET in early disease stages and attention to both cardiac and peripheral profiles in diverse populations will guide further HFpEF research in novel mechanisms and therapeutics.

Establishment and effectiveness evaluation of pre-test probability model of coronary heart disease combined with cardiopulmonary exercise test indexes

To establish a pre-test probability model of coronary heart disease (CHD) combined with cardiopulmonary exercise test (CPET) indexes and to compare the clinical effectiveness with Duke clinical score (DCS) and updated Diamond-Forrester model (UDFM), thus further explore the predictive value. 342 cases were used to establish the prediction model equation and another 80 cases were used to verify the effectiveness. The patients were divided into CHD group (n = 157) and non-CHD group (n = 185) according to coronary artery stenosis degree >50% or not. Combining DCS and UDFM as reference models with CPET indexes, a multivariate logistic regression model was established. The area under the ROC curve of the three models were calculated to compare the predictive effectiveness. There were significant differences in gender, chest pain type, myocardial infarction history, hypertension history, smoking, pathological Q wave and ST-T change between two groups (P < 0.01), as well as age, LVEF, heart rate at anaerobic domain, peak oxygen uptake in kilograms of body weight, percentage of peak oxygen uptake to the predicted value, the oxygen uptake efficiency slope and carbon dioxide ventilation equivalent slope (P < 0.05). Multivariate analysis showed gender, age, chest pain type, myocardial infarction history, hypertension history, smoking, pathological Q wave, ST-T change, and peak oxygen pulse were independent risk factors of CHD. The pre-test probability model of CHD combined with CPET indexes has good distinguish and calibrate ability, its prediction accuracy is slightly better than DCS and UDFM, which still needs to be verified externally in more samples.

Reference Values of Cardiopulmonary Exercise Test Parameters in the Contemporary Paediatric Population

BackgroundThe evaluation of health status by cardiopulmonary exercise test (CPET) has shown increasing interest in the paediatric population. Our group recently established reference Z-score values for paediatric cycle ergometer VO2max, applicable to normal and extreme weights, from a cohort of 1141 healthy children. There are currently no validated reference values for the other CPET parameters in the paediatric population. This study aimed to establish, from the same cohort, reference Z-score values for the main paediatric cycle ergometer CPET parameters, apart from VO2max.ResultsIn this cross-sectional study, 909 healthy children aged 5–18 years old underwent a CPET. Linear, quadratic, and polynomial mathematical regression equations were applied to identify the best CPET parameters Z-scores, according to anthropometric parameters (sex, age, height, weight, and BMI). This study provided Z-scores for maximal CPET parameters (heart rate, respiratory exchange ratio, workload, and oxygen pulse), submaximal CPET parameters (ventilatory anaerobic threshold, VE/VCO2 slope, and oxygen uptake efficiency slope), and maximum ventilatory CPET parameters (tidal volume, respiratory rate, breathing reserve, and ventilatory equivalent for CO2 and O2).ConclusionsThis study defined paediatric reference Z-score values for the main cycle ergometer CPET parameters, in addition to the existing reference values for VO2max, applicable to children of normal and extreme weights. Providing Z-scores for CPET parameters in the paediatric population should be useful in the follow-up of children with various chronic diseases. Thus, new paediatric research fields are opening up, such as prognostic studies and clinical trials using cardiopulmonary fitness outcomes.Trial registration NCT04876209—Registered 6 May 2021—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04876209.

Translational and Rotational Postural Aberrations Are Related to Pulmonary Functions and Skill-Related Physical Fitness Components in Collegiate Athletes.

This study assessed the relationship between body posture displacements, cardiopulmonary exercise testing (CPET), and skill-related physical fitness tests. One hundred male (60%) and female collegiate athletes (22.2 ± 4 yrs) with normal body mass indexes (BMI up to 24.9) were assessed via the PostureScreen Mobile® app to quantify postural displacements such as head, thorax, and pelvis rotations and translations. CPET and physical performance tests, including the agility t-test, vertical jump test, stork static balance test (SSBT), and dynamic Y-balance test (YBT), were performed. Spearman correlation (r) and p-values are reported. The postural parameters were found to have moderate-to-high associations with the CPET and agility test, moderate correlations with the vertical jump test and SSBT (head and pelvic postures only), and weak correlations with the YBT. As the postural parameters were more asymmetric, both the CPET and performance skills scores were worse. For example: (1) a medium positive correlation was found between cranio-vertebral angle (CVA) and the vertical jump test (r = 0.54; p-value < 0.001) and SSBT (r = 0.57; p-value < 0.001), while a strong negative correlation was found between CVA and the agility test (r = -0.86; p-value < 0.001). (2) A strong positive correlation was found between CVA and oxygen uptake efficiency slope, load watts VO2 at VT, VO2/kg, and load watts at the respiratory compensation point (RCP) (r = 0.65 and r = 0.71; p < 0.001). Conversely, a significant negative correlation was found between CVA and VE/VO2 at VT (r = -0.61; p < 0.001). Postural rotations and translations of the head, thorax, and pelvis were statistically correlated with the physical performance skills and CPET in the young collegiate athletes. There were moderate-to-high associations with cardiopulmonary functions and the agility tests, moderate correlations with the vertical jump test, and weak correlations with the YBT. Postural alignment may be important for optimal physical performance and optimal cardiopulmonary function. Further research is necessary to elucidate the reasons for these correlations found in our sample of young and healthy athletes.

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.

Predictors of cardiopulmonary exercise testing in COPD patients according to the Weber classification

BackgroundWeber classification stratifies cardiac patients based on peak oxygen consumption (V̇O2), the gold-standard measure of exercise capacity. ObjectiveTo determine if Weber classification is a useful tool to discriminate clinical phenotypes in COPD patients and to evaluate if disease severity and other clinical measures can predict V̇O2peak. MethodsThree hundred and six COPD patients underwent cardiopulmonary exercise testing (CPX) and were divided according to Weber class: 1) Weber A (n = 34); 2) Weber B (n = 88); 3) Weber C (n = 138); and 4) Weber D (n = 46). ResultsWeber class D patients demonstrated a reduced V̇O2 peak, heart rate (HR), minute ventilation (V̇E), oxygen (O2) pulse, circulatory power (CP), oxygen uptake efficiency slope (OUES), oxygen saturation (SpO2%), delta (Δ)HR and ΔSpO2 when compared to Weber A and B (p<0.05). Moreover, Dyspnea and the V̇E/carbon dioxide production (V̇CO2) slope were higher in Weber D compared with Weber C and A (p<0.001). Hierarchical regression analysis demonstrated significant predictors of V̇O2peak (R2= 0.131; Adj R 2 = 1.25), including HR (β=0.5757; t = 5.7; P<0.001) and forced expiratory volume in one second (FEV1) (β=0.119; t = 2.16; P<0.03). Among the Weber C + D groups, predictors of V̇O2peak (R = 0.78; R2= 0.60; Adj R2 =0.59), dyspnea (β=0.076; t = 1.111; P<0.27) and maximal voluntary ventilation (MVV) (β=0.75; t = 1.14; P<0.00). ConclusionWeber classification may be a useful tool to stratify cardiorespiratory fitness in COPD patients. Other clinical measures may be useful in predicting peak V̇O2 in mild-to-severe COPD, moreover different phenotypes may be important tool to improve physical capacity of chronic disease patients.

Cardiorespiratory fitness is an important marker of cognitive performance in older Latin Americans

AbstractBackgroundOur previous research with older non‐Hispanic whites demonstrated that with increasing cardiorespiratory fitness (CRF) there was a concomitant linear increase in processing speed (PS) performance. PS has also been found in a number of reports as a potential precursor to memory decline associated with Alzheimer’s disease and cognitive aging. The purpose of this study was to examine whether the same cognitive benefits imbued by CRF generalize within a healthy Latino aging community living in Costa Rica (CR).Method415 community dwelling older adults (315 CR and 100 non‐Hispanic whites living in the United States) with a mean age of 71 (SD = 5.29) years old were recruited from the Epidemiology and Development of Alzheimer’s Disease (EDAD), a large international study of Latino cognitive aging. Participants completed neuropsychological testing and a graded treadmill exercise stress test. We compared the relationship between Oxygen Uptake Efficiency Slope (OUES) and a composite measure of PS (Digit Symbol, Block Design, and Stroop Color Naming). Confirmatory factor analysis was conducted.ResultCRF (OUES) significantly predicted PS within the CR (B = 0.50; p &lt; .001) group and non‐Hispanic white (B = 0.25; p &lt; .05) group after controlling for age and sex. The relationship between CRF and the PS factor showed a non‐significant misfit when the relationship was constrained to be equal on both groups (χ² (1) = 0.39, p = 0.53), hence the relationship is equivalent between groups.ConclusionIn a healthy sample of older individuals living in CR we found the same score profile and interrelationships that were identified among non‐Hispanic whites living in the United States. CRF and PS are clinically meaningful therapeutic targets for dementia prevention among older Latin Americans.

Oxygen uptake efficiency slope measured by cardiopulmonary exercise testing: applicability analysis of the available prediction equations in a Brazilian healthy sample

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). Background Oxygen uptake efficiency slope (OUES) measured by cardiopulmonary exercise testing (CPET) is a measure derived from submaximal oxygen uptake values and has prognostic significance in heart failure patients. Measured values are compared to reference standards for an adequate individual assessment. However, current reference values prediction equations have applicability limitations due to differences in ergometer and sample characteristics (age range and nationatilies), which may impact external validation, as international heterogeneities in peak oxygen uptake values have already been demonstrated by Milani et al. and Peterman et al. Purpose To analyze the applicability of the available prediction equations for OUES in a healthy Brazilian sample from the Midwest region. Methods Cross-sectional study of subjects assessed by treadmill CPET in the Brazilian Midwest region between January/2011 to March/2020. The inclusion criteria were CPET performed on a treadmill in healthy subjects aged 20 years or older, and with respiratory exchange ratio ≥ 1.0. The exclusion criteria were any history of cardiovascular or pulmonary disease, presence of cardiovascular risk factors (such as hypertension, diabetes mellitus, current smoking, and obesity) and abnormalities on CPET. The following available prediction equations were used for comparisons with the measured OUES: 1) Buys et al. from Belgium/Netherlands; 2) Hollemberg et al. from United States; 3) Sun et al. from United States; 4) Brazilian prediction equations calculated in our same sample using sex, age and anthropometric variables. Statistical comparisons between measured and predicted OUES were performed using Spearman correlation test and Bland-Altman agreement analysis. Results During the study period, 7,843 CPETs were performed and included for eligibility. After applying the inclusion and exclusion criteria, 3,544 assessments of healthy individuals were included (1,574 women; 1,970 men; age 20 to 80 years). All correlations between measured and predicted values were significant, with rho ranging from 0.325 to 0.396 in females and from 0.391 to 0.450 in males (Figure 1). The mean errors by the Bland-Altman agreement analysis were heterogeneous between the OUES predition equations, with better results in our Brazilian equation. Greater bias were observed in the equation by Sun et al. for both sexes, in the equation from Buys et al. for females and in the equation by Hollemberg et al. for males (Figure 2). Conclusions The applicability analysis of the international prediction equations for OUES revealed great heterogeneity, limiting the external validation of the available equations, and highlighting the importance of using country-specific reference values for OUES to ensure a correct individual evaluation.