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OBJECTIVE: To identify the association between cardiopulmonary exercise testing (CPET) and outcomes of radical cystectomy (RC), as RC is historically associated with high rates of short- and long-term morbidity and mortality. METHODS: This quantitative systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. An electronic literature search was conducted to identify all relevant studies evaluating the relationship between CPET parameters and RC outcomes. The primary outcome was short-term mortality. Secondary outcomes included hospital length of stay (LOS) and rate of serious adverse events as defined by the Clavien-Dindo classification. RESULTS: The search identified six studies for inclusion. A total of 546 patients underwent CPET prior to RC. There were significantly more deaths following RC observed in patients with poorer cardiopulmonary function (risk ratio RR 5.80, 95% confidence interval 4.96-6.78). There was no significant association between CPET parameters and adverse events or hospital LOS. CONCLUSIONS: The present systematic review and meta-analysis identified a greater risk of 90-day mortality in patients with poorer cardiorespiratory function, as measured by CPET. However, there remains a paucity of robust clinical data and further high-quality studies are required to verify these results.

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Background: Supramaximal constant work rate tests (CWR) elicit intense hyperventilation, thus potentially up-shifting ventilation (⩒E)-to-carbon dioxide (CO2) responses when compared to graded exercise tests (GXT) in athletes. We predicted higher ventilatory efficiency on supramaximal CWR using a new method, challenging the classic orthodox interpretation of an increased ⩒E-⩒CO2 as ventilatory inefficiency. This misinterpretation could make difficult to differentiate between physiological hyperventilation from heart disease conditions in athletes. Methods: On different days, a GXT and a CWR at 110% of the maximal velocity achieved in the GXT were performed. Twenty-seven athletes completed the two tests and were compared for usual (linear regression) and log-transformed new variables for ventilatory efficiency through paired t-Student statistics. Results: The ⩒E-⩒CO2 slope (31.4 ± 4.9 vs. 26.2 ± 3.4, p < .001), ⩒E-⩒CO2 intercept (7.2 ± 7.5 vs. 2.8 ± 4.2, p < .007), ⩒E/⩒CO2 nadir (33.0 ± 3.6 vs. 25.4 ± 2.2, p < .001), ⩒CO2-log⩒E slope (10.8 ± 2.9 vs. 6.9 ± 2.2 L*logL-1, p < .001), and η⩒E (36.0 ± 12 vs. 22.8 ± 8.1%, p < .001) values were all significantly higher in the CWR compared to the GXT. We registered a bi-modal nadir response for ⩒E/⩒CO2 on CWR for 22 out of 27 subjects for the first time. A weak association was observed between ⩒E/⩒CO2 nadir (coefficient of determination ~ 27%) and time to exhaustion. Conclusions: The new method allows us to improve the quantification and interpretation of ventilatory efficiency in athletes, avoiding misinterpretation due to the up-shifting elicited by the usual ⩒E-⩒CO2 slope and ⩒E/⩒CO2 nadir indices, which may be confounded with ventilatory inefficiency. This study suggests that ventilatory changes underpin better ventilatory efficiency during CWR.

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Objective: The main objective of this study was to compare lactate thresholds and aerobic capacity from a graded-intensity exercise test (GXT) for near-infrared spectroscopy measurements in healthy, untrained individuals and highly trained athletes. Methods: This study included 29 untrained students (13 females) and 27 highly trained speed skaters (13 females). A maximal effort GXT was performed on a cycloergometer. The lactate-based aerobic and anaerobic thresholds, and the corresponding thresholds for muscle oxygen saturation (SmO2), were determined. Results: The power values determined for all thresholds were significantly higher in female and male speed skaters compared to male and female college students. SmO2 at anaerobic thresholds was significantly lower in female speed skaters than in female students. Both female and male skaters showed greater changes in SmO2 after the GXT compared to students. The recovery did not significantly differ between groups within gender. There was a significant positive correlation in females between the rate of muscle reoxygenation and VO2max power (r = 0.610). In speed skaters, the rate of muscle reoxygenation was not significantly higher than students and correlated positively with VO2max (r = 0.449). Conclusions: The SmO2 at the exercise thresholds, during and after maximal exercise, depends on the training status of the individual. The participants with a higher physical fitness level showed greater decreases in ΔSmO2 at the AT level, as well as after maximal exercise. SmO2 corresponding to the well-established exercise thresholds may be applied to guide training prescription. The rate of muscle reoxygenation after a GXT was also dependent on the aerobic capacity of the participants.

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Highly trained aerobic athletes progressively use most of their breathing reserve with increased exercise intensity during whole-body exercise. Additionally, females typically present proportionally smaller lungs than males. Therefore, sex, exercise intensity, and breathing reserve use likely influence the volume and time in which respiratory parameters vary between consecutive breaths during whole-body exercise. However, breath-by-breath variability has been scarcely investigated during exercise. Accordingly, we sought to investigate breath-by-breath pulmonary ventilation (V̇E), tidal volume (VT), and respiratory frequency (fR) variability during a maximal treadmill incremental exercise test in 17 females and 18 males highly trained professional endurance runners. The breath-by-breath variability was analyzed by root mean square of successive differences (RMSSD) within 1-minute windows. Females had lower absolute and percent predicted forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) than males, as well as lower height-adjusted absolute FVC than males. V̇E and VT reserve use were similar between the sexes at peak exercise. While RMSSDV̇E and RMSSDfR did not change over exercise (P > 0.05), RMSSDVT progressively decreased (P < 0.001). RMSSDVT was negatively correlated with VT reserve use only in males. Females showed lower RMSSDV̇E than males during the entire exercise test (P < 0.001). At iso-V̇E reserve use, between-sex differences in RMSSDV̇E persisted (P = 0.003). Our findings indicate that exercise intensity decreases VT variability in professional runners, which is linked to VT reserve use in males but not females. Additionally, the female sex lowers V̇E variability regardless of exercise intensity and V̇E reserve use.

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To investigate the potential contribution of chest wall muscle area (CWMA) to the ventilatory efficiency and exercise capacity in patients with Systemic Sclerosis (SSc) without interstitial lung disease (ILD). Forty-four consecutive SSc patients [F = 37, median age 53.5 years (IQR 43.5-58)] were examined using chest high-resolution computed tomography (HRCT), pulmonary function tests and cardiopulmonary exercise testing (CPET). The CWMA was evaluated at the level of the ninth thoracic vertebra on CT images by two independent evaluators blinded to the patient information. CPET parameters analyzed were maximum oxygen uptake (VO2 max) and VO2 at anaerobic threshold (VO2@AT); minute ventilation (VE); maximum tidal volume (VT). A statistically significant positive correlation was found between CWMA and maximum workload (r = 0.470, p < 0.01), VO2 max ml/min (r = 0.380, p < 0.01), VO2@AT (r = 0.343, p < 0.05), VE (r = 0.308, p < 0.05), VT (r = 0.410, p < 0.01) and VO2/heart rate (r = 0.399, p < 0.01). In multiple regression analysis, VO2 max (ml/min) was significantly associated with CWMA [ß coefficient = 5.226 (95% CI 2.824, 7.628); p < 0.001], diffusing capacity for carbon monoxide (DLco) [ß coefficient = 6.749 (95% CI 1.460, 12.039); p < 0.05] and body mass index (BMI) [ß coefficient = 41.481 (95% CI 8.802, 74.161); p < 0.05]. In multiple regression analysis, maximum workload was significantly associated with CWMA [ß coefficient = 0.490 (95% CI 0.289, 0.691); p < 0.001], DLco [ß coefficient = 0.645 (95% CI 0.202, 1.088); p < 0.01] and BMI [ß coefficient = 3.747 (95% CI 1.013, 6.842); p < 0.01]. In SSc-patients without ILD, CWMA represents an important variable in exercise capacity and can be evaluated by the mediastinal window available in the HRCT images required for lung disease staging.

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Standard cardiopulmonary exercise testing (CPET) produces a rich dataset but its current analysis is often limited to a few derived variables such as maximal or peak oxygen uptake (V̇O2). We tested whether breath-by-breath CPET data could be used to determine sample entropy (SampEn) in 81 healthy children and adolescents (age 7-18 years old, equal sex distribution). To overcome challenges of the relatively small time-series CPET data size and its nonstationarity, we developed a Python algorithm for short-duration physiological signals. Comparing pre- and post-ventilatory threshold (VT1) CPET phases, we found: (1) SampEn decreased by 9.46% for V̇O2 and 5.01% for V̇CO2 (p < 0.05), in the younger, early-pubertal participants; and (2) HR SampEn fell substantially by 70.8% in the younger and 77.5% in the older participants (p < 0.001). Across all ages, females exhibited greater HR SampEn than males during both pre- and post VT1 CPET phases by 14.10% and 23.79%, respectively, p < 0.01. In females, late-pubertal had 17.6% lower HR SampEn compared to early-pubertal participants (p < 0.05). Breath-by-breath gas exchange and HR data from CPET are amenable to SampEn analysis that leads to novel insight into physiological responses to work intensity, and sex and maturational effects.

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Background: Male and female patients with hypertrophic cardiomyopathy (HCM) differ in physiologic characteristics and hemodynamics. Little is known about gender-related differences in left atrial (LA) strain and exercise capacity. The aim of this study was to assess the gender-related differences in the relationship between exercise capacity and cardiac function including LA function in patients with HCM. Methods: Five hundred and thirty-two patients with HCM undergoing exercise stress echocardiography and cardiopulmonary exercise testing (CPET) were prospectively recruited between October 2015 and April 2019 as part of a cohort study in a quaternary referral center. To reduce potential confounding factors, propensity score (PS) matching was performed in 420 patients. LA strain mechanics were evaluated using speckle-tracking echocardiography. Results: The majority of patients were male, comprising 58% of the total. Female HCM patients were older (54±14 vs. 50±15 years, P=0.002). After PS matching, percent-predicted peak VO2 was similar between the genders (67.5%±20.7% vs. 65.8%±21.8%, P=0.41), even though female HCM patients had lower peak VO2 (17.7±5.9 vs. 24.1±8.3 mL/kg/min, P<0.001). Left ventricular (LV) diastolic function was worse for female HCM patients. This is shown by worse E/e' ratio (15.0±5.9 vs. 12.9±6.4, P<0.001) and larger LA volume in respect to LV (0.88±0.35 vs. 0.74±0.31, P<0.001), compared with male HCM patients. The gender-related differences in LA reservoir strain were more evident for patients aged 60 years and older (27.5%±8.8% vs. 30.9%±9.1%, P=0.03). LA reservoir strain was found to have a significant association with exercise capacity in both male and female HCM patients (for females, ß=0.27, P=0.001; for males, ß=0.27, P<0.001), independent of LV diastolic dysfunction and stroke volume. Conclusions: Gender-related differences in LA reservoir strain were increasingly evident for older HCM patients aged 60 years and older. LA reservoir strain was an independent determinant of percent-predicted peak VO2 in male and female patients, underpinning the importance of LA function in determining exercise capacity in HCM.

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A case report of a severely dyspnoeic kyphoscoliotic patient intended for an elective major thoracic surgery for suspected lung malignancy. With baseline near maximal breathing frequency and shallow breaths and poor lung mechanics, the first encountered anaesthetist considered this patient too high risk for lobectomy. This case illustrated the application of cardiopulmonary exercise testing to provide an objective assessment of the patient's functional capacity, ventilatory efficiency and delineation of modifiable respiratory components that guide the formulation of individualized prehabilitation programme. It also depicted the perioperative role of an off-label use of incentive spirometry in providing visual feedbacks and led to subsequent assessment breathing pattern alternation. Patient underwent the lung resection uneventfully and returned to normal lifestyle on postoperative day 4.

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AIMS: Systemic sclerosis complicated by pulmonary arterial hypertension (SSc-PAH) is a rare condition with poor prognosis. The majority of patients are categorized as intermediate risk of mortality. Cardiovascular magnetic resonance (CMR) is well placed to reproducibly assess right heart size and function, but most patients with SSc-PAH have less overtly abnormal right ventricles than other forms of PAH. The aim of this study was to assess if exercise CMR measures of cardiac size and function could better predict outcome in patients with intermediate risk SSc-PAH compared with resting CMR. METHODS AND RESULTS: Fifty patients with SSc-PAH categorized as intermediate risk underwent CMR-augmented cardiopulmonary exercise testing. Most patients had normal CMR-defined resting measures of right ventricular (RV) size and function. Nine (18%) patients died during a median follow-up period of 2.1 years (range 0.1-4.6). Peak exercise RV indexed end-systolic volume (ESVi) was the only CMR metric to predict prognosis on stepwise Cox regression analysis, with an optimal threshold < 39 mL/m2 to predict favourable outcome. Intermediate-low risk patients with peak RVESVi < 39 mL/m2 had significantly better survival than all other combinations of intermediate-low/-high risk status and peak RVESVi< or ≥39 mL/m2. In our cohort, ventilatory efficiency and resting oxygen consumption (VO2) were predictive of mortality, but not peak VO2, peak cardiac output, or peak tissue oxygen extraction. CONCLUSION: Exercise CMR assessment of RV size and function may help identify SSc-PAH patients with poorer prognosis amongst intermediate risk cohorts, even when resting CMR appears reassuring, and could offer added value to clinical PH risk stratification.

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OBJECTIVE: Construction nomogram was to effectively predict long-term prognosis in patients with non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: The nomogram is developed by a retrospective study of 347 patients with NSCLC who underwent cardiopulmonary exercise testing (CPET) before surgery from May 2019 to February 2022. Cross-validation divided the data into a training cohort and validation cohort. The discrimination and accuracy ability of the nomogram were proofed by concordance index (C-index), calibration curve, receiver operating characteristic (ROC) curve, the area under the curve (AUC), and time-dependent ROC in validation cohort. RESULTS: Age, intraoperative blood loss, VO2 peak, and VE/VCO2 slope were included in the model of nomogram. The model demonstrated good discrimination and accuracy with C-index of 0.770 (95% CI: 0.712-0.822). AUC of 6 (AUC: 0.789, 95% CI: 0.726-0.851) and 12 months (AUC: 0.787, 95% CI: 0.724-0.850) were shown in ROC. Time-independent ROC maintains a good effect within 12 months. CONCLUSION: We developed a nomogram based on CPET. This model has a good ability of discrimination and accuracy. It could help clinicians to make treatment decision in clinical decision.

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BACKGROUND: Invasive cardiopulmonary exercise testing (iCPET) combines traditional cardiopulmonary exercise testing with invasive hemodynamic measurements to assess exercise intolerance, which can be caused by preload insufficiency (PI), characterized by low ventricular filling pressures and reduced cardiac output during exertion. We hypothesize that plasma catecholamine levels at rest and during exercise correlate with hemodynamic parameters in PI. METHODS: We included adult patients who underwent iCPET for exercise intolerance and had plasma catecholamines measured at rest and peak exercise. RESULTS: Among 84 patients, PI was identified in 57 (67.8 %). Compared to patients without PI, those with PI were younger [median (IQR) 37 (28, 46) vs 47 (39,55) years, p = 0.005] and had lower workload at peak exercise [81 (66, 96) vs 95 (83.5, 110.50) Watts, p = 0.006]. Patients with PI had higher heart rates at rest and peak exercise [87 (78, 97) vs 79 (74, 87) bpm, p = 0.04; and 167 (154, 183) vs 156 (136, 168) bpm, p = 0.01, respectively]. In all patients, epinephrine and norepinephrine at peak exercise directly correlated with peak workload (r:0.41, p < 0.001 and r:0.47, p < 0.001, respectively). Resting epinephrine was higher in patients with PI [136 (60, 210) vs 77 (41, 110) pg/mL, p = 0.02]. There was no significant difference in the change in catecholamines from rest to peak exercise between patients with or without PI. CONCLUSION: PI patients exhibited elevated heart rate and epinephrine at rest, indicating increased sympathetic activity. We did not find strong associations between catecholamines and cardiac filling pressures, suggesting that catecholamine levels are predominantly influenced by peak workload.

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INTRODUCTION: Survivors of severe COVID-19 face complex challenges and a high degree of pulmonary sequelae. Therefore, we aim to describe their ongoing health burden. METHODS: In this single-center prospective cohort study, COVID-19 ICU survivors were invited 3 and 6 months after ICU discharge. We examined pulmonary function with pulmonary function tests (PFT) and cardiopulmonary exercise testing (CPET), and we established health-related quality of life (HRQL) and health status (HS) with the EuroQol five-dimension five-level (EQ-5D-5L), the short-form health survey 12 (SF-12), and the modified British Medical Research Council dyspnea scale (mMRC) questionnaires. RESULTS: Out of the 53 individuals screened, 23 participated in this study. Throughout both assessment points, participants maintained PFT results within range, apart from a decline in the transfer factor of the lung for carbon monoxide (TLCO). CPET showed improved fitness but persistent ventilatory deficiencies, indicated by altered dead space ventilation (VD/VT) and elevated arterial-alveoli gradient for oxygen (AaDO2). HRQL and HS remained compromised, with both physical (PCS) and mental component summary (MCS) scores significantly lower than the standardized norm population scores. Also, there was a rise in the prevalence of issues related to mobility, pain/discomfort, and anxiety/depression, and an increase in reported dyspnea. CONCLUSION: These results enhance our comprehension of the complex difficulties faced by COVID-19 ICU survivors. Six months post-discharge, CPET revealed the presence of ventilatory insufficiencies. Additionally, there was a decline in HRQL and HS, notably affected by mental health concerns and an increase in the level of dyspnea.

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BACKGROUND: After COVID-19 infection, 10-20% of patients suffer from varying symptoms lasting more than 12 weeks (Long COVID, LC). Exercise intolerance and fatigue are common in LC. The aim was to measure the maximal exercise capacity of the LC patients with these symptoms and to analyze whether this capacity was related to heart rate (HR) responses at rest and during exercise and recovery, to find out possible sympathetic overactivity, dysautonomia or chronotropic incompetence. METHODS: Cardiopulmonary exercise test was conducted on 101 LC patients, who were admitted to exercise testing. The majority of them (86%) had been treated at home during their acute COVID-19 infection. Peak oxygen uptake (VO2peak), maximal power during the last 4 min of exercise (Wlast4), HRs, and other exercise test variables were compared between those with or without subjective exercise intolerance, fatigue, or both. RESULTS: The measurements were performed in mean 12.7 months (SD 5.75) after COVID-19 infection in patients with exercise intolerance (group EI, 19 patients), fatigue (group F, 31 patients), their combination (group EI + F, 37 patients), or neither (group N, 14 patients). Exercise capacity was, in the mean, normal in all symptom groups and did not significantly differ among them. HRs were higher in group EI + F than in group N at maximum exercise (169/min vs. 158/min, p = 0.034) and 10 min after exercise (104/min vs. 87/min, p = 0.028). Independent of symptoms, 12 patients filled the criteria of dysautonomia associated with slightly decreased Wlast4 (73% vs. 91% of sex, age, height, and weight-based reference values p = 0.017) and 13 filled the criteria of chronotropic incompetence with the lowest Wlast4 (63% vs. 93%, p < 0.001), VO2peak (70% vs. 94%, p < 0.001), the lowest increase of systolic blood pressure (50 mmHg vs. 67 mmHg, p = 0.001), and the greatest prevalence of slight ECG-findings (p = 0.017) compared to patients without these features. The highest prevalence of chronotropic incompetence was seen in the group N (p = 0.022). CONCLUSIONS: This study on LC patients with different symptoms showed that cardiopulmonary exercise capacity was in mean normal, with increased sympathetic activity in most patients. However, we identified subgroups with dysautonomia or chronotropic incompetence with a lowered exercise capacity as measured by Wlast4 or VO2peak. Subjective exercise intolerance and fatigue poorly foresaw the level of exercise capacity. The results could be used to plan the rehabilitation from LC and for selection of the patients suitable for it.

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Quantitating exercise ventilatory and gas exchange dynamics affords insights into physiological control processes and cardiopulmonary dysfunction. We designed a novel waveform, the chirp waveform, to efficiently extract moderate intensity exercise response dynamics. In the chirp waveform, work rate fluctuates sinusoidally with constant amplitude as sinusoidal period decreases progressively from approximately 8.5 to 1.4 minutes over 30 minutes of cycle ergometry. We hypothesized that response dynamics of pulmonary ventilation (V̇E) and gas exchange (V̇O2 and V̇CO2) extracted from chirp waveform are similar to those obtained from step-wise transitions. Thirty-one participants (14 young-healthy, 7 older-healthy, 10 COPD patients) exercised on three occasions. Participants first performed ramp-incremental exercise for gas exchange threshold (GET) determination. In randomized order, the next two visits involved either chirp or step-wise waveforms. Work rate amplitude (20W to ∼95% GET work rate) and exercise duration (30 min) were the same for both waveforms. A first-order linear transfer function with system gain (G) and time constant (τ) characterized response dynamics. Agreement between model parameters extracted from chirp and step-wise waveforms was established using Bland-Altman analysis and Rothery's Concordance Coefficient (RCC). V̇E, V̇O2, and V̇CO2 Gs showed no systematic bias (p>0.178) and moderate-to-good agreement (RCC>0.772, p<0.01) between waveforms. Similarly, no systematic bias (p=0.815) and good agreement (RCC=0.837, p<0.001) was found for τV̇O2. Despite moderate agreement for τV̇CO2 (RCC=0.794, p<0.001) and τV̇E (RCC=0.722, p=0.083), chirp τ was less (-6.9(11.7)s and -12.2(22.5)s, respectively). We conclude that the chirp waveform is a promising method for measuring exercise response dynamics and investigating physiological control mechanisms.

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BACKGROUND: A high minute ventilation/rate of carbon dioxide production (V̇E/V̇co2) slope during exercise is prognostic for cardiovascular death. Recent data indicate that adults with either controlled or untreated primary hypertension, but not those with uncontrolled hypertension, exhibit a higher V̇E/V̇co2 slope during exercise. However, the sample sizes were modest. Therefore, we used the Fitness Registry and the Importance of Exercise National Database to determine whether adults with hypertension, particularly those with controlled or untreated hypertension, exhibit higher V̇E/V̇co2 slopes compared with adults without hypertension. METHODS AND RESULTS: Using the Fitness Registry and the Importance of Exercise National Database, we isolated primary hypertension by excluding those with any disease other than hypertension or taking any medications other than antihypertension medications. We also excluded current smokers and those with obesity. The V̇E/V̇co2 slope was determined during a peak cycling exercise test. All data are presented as median [interquartile range]. We compared groups using linear regression adjusted for age, male/female, and body mass index. The characteristics of the entire sample (n=4109) were age, 42 [18] years; 48% women; body mass index, 26 [4] kg/m2. The V̇E/V̇co2 slope did not differ between adults with hypertension (n=1940; 24.7 [3.7]) compared with those without hypertension (n=2169; 24.9 [3.8]) (hypertension versus no hypertension, P=0.31; overall model: R2=0.07, F4,4104=73.0; P<0.001). Further, the V̇E/V̇co2 slope did not differ between adults with medication-controlled hypertension (n=107; 24.4 [3.0]), untreated hypertension (n=1626; 24.8 [3.9]), uncontrolled hypertension (n=207; 24.8 [3.0]), or those without hypertension (n=2169; 24.9 [3.8]) (hypertension subgroup versus no hypertension, P≥0.06; overall model: R2=0.07, F6,4102=49.6, P<0.001). CONCLUSIONS: Primary hypertension is not associated with V̇E/V̇co2 slope in the Fitness Registry and the Importance of Exercise National Database.

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Background and Objectives: Obstructive sleep apnea (OSA) is common in cardiovascular disease (CVD), although positive airway pressure (PAP) treatment has not been demonstrated to improve the cardiovascular outcome. The objective of this study is to investigate the impact of adherence to PAP therapy on cardiopulmonary exercise testing (CPET) performance in patients with concomitant OSA and CVD. Materials and Methods: This preliminary study involved symptomatic OSA patients requiring PAP treatment who had CVD. All subjects underwent polysomnography, echocardiography, and CPET at baseline. After 6 to 12 months of PAP treatment, CPET performance was re-assessed. The changes in CPET parameters before and after PAP treatment were compared between patients who were adherent to PAP and patients who were not adherent to PAP. Results: A total of 16 OSA patients with an apnea-hypopnea index of 32.0 ± 23.4 were enrolled. Patients were classified into the adherent (n = 9) and non-adherent (n = 7) groups with regard to PAP adherence. After 6 to 12 months of PAP treatment, the PAP-adherent group showed a greater increase in peak VO2 than the PAP-non-adherent group, but the difference between the two groups was not significant (p = 0.581). The decrease in ventilatory equivalent for the carbon dioxide slope (VE/VCO2) was significantly greater in the PAP-adherent group compared to the PAP-non-adherent group (p = 0.030). Conclusions: Adherence to PAP therapy for OSA is associated with an improvement in the VE/VCO2 slope, as an index of the ventilatory response to exercise, in patients with CVD. Screening for sleep apnea in CVD patients may be warranted, and strategies to optimize adherence to PAP in these patients are beneficial. Further evidence is needed to elucidate whether CPET could be routinely used to monitor treatment responses of OSA to PAP therapy in patients with CVD.

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BACKGROUND: Endurance athletes (EA) are an emerging population of focus for cardiovascular health. The oxygen uptake efficiency plateau (OUEP) is the levelling-off period of ratio between oxygen uptake (VO2) and ventilation (VE). In the cohort of EA, we externally validated prediction models for OUEP and derived with internal validation a new equation. METHODS: 140 EA underwent a medical assessment and maximal cycling cardiopulmonary exercise test. Participants were 55% male (N = 77, age = 21.4 ± 4.8 years, BMI = 22.6 ± 1.7 kg·m- 2, peak VO2 = 4.40 ± 0.64 L·min- 1) and 45% female (N = 63, age = 23.4 ± 4.3 years, BMI = 22.1 ± 1.6 kg·m- 2, peak VO2 = 3.21 ± 0.48 L·min- 1). OUEP was defined as the highest 90-second continuous value of the ratio between VO2 and VE. We used the multivariable stepwise linear regression to develop a new prediction equation for OUEP. RESULTS: OUEP was 44.2 ± 4.2 mL·L- 1 and 41.0 ± 4.8 mL·L- 1 for males and females, respectively. In external validation, OUEP was comparable to directly measured and did not differ significantly. The prediction error for males was - 0.42 mL·L- 1 (0.94%, p = 0.39), and for females was + 0.33 mL·L- 1 (0.81%, p = 0.59). The developed new prediction equation was: 61.37-0.12·height (in cm) + 5.08 (for males). The developed model outperformed the previous. However, the equation explained up to 12.9% of the variance (R = 0.377, R2 = 0.129, RMSE = 4.39 mL·L- 1). CONCLUSION: OUEP is a stable and transferable cardiorespiratory index. OUEP is minimally affected by fitness level and demographic factors. The predicted OUEP provided promising but limited accuracy among EA. The derived new model is tailored for EA. OUEP could be used to stratify the cardiorespiratory response to exercise and guide training.

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Background: This study investigated the prognostic value of cardiovascular magnetic resonance (CMR)-derived global coronary flow reserve (G-CFR) in addition to cardiopulmonary exercise testing (CPET) variables in patients with acute myocardial infarction (AMI). Methods and Results: We investigated 127 patients with AMI who underwent primary or urgent percutaneous coronary intervention (PCI) and post-intervention CMR and CPET. The incidence of major cardiac and cerebrovascular events (MACCE), defined as all-cause death, recurrent non-fatal myocardial infarction, re-hospitalization due to congestive heart failure, and stroke, was evaluated (median follow-up, 2.8 years). Patients with MACCE (n=14) had lower ejection fraction (EF) (50 [43-59] vs. 58 [51-63]%; P=0.014), lower G-CFR (1.74 [1.19-2.20] vs. 2.40 [1.61-3.66]; P=0.008), and lower peak oxygen consumption (V̇O2) (15.16±2.64 vs. 17.19±3.70 mL/kg/min; P=0.049) than patients without MACCE. G-CFR<2.33 and peak V̇O2 <15.65 mL/kg/min (cut-off values derived from receiver operating characteristic curve analyses) were significantly associated with the incidence of MACCE (log-rank test, P=0.01). The combination of low G-CFR and low peak V̇O2 improved risk discrimination for MACCE when added to the reference clinical model including age, male sex, post-PCI peak creatine kinase, EF, and left anterior descending artery culprit lesion. Conclusions: G-CFR and peak V̇O2 showed incremental prognostic information compared with the reference model using historically important clinical risk factors, indicating that this approach may help identify high-risk patients who suffer subsequent adverse events.

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Objective: To investigate the ventilatory and circulatory differences between eccentric (ECC) and concentric (CON) cycling exercise at submaximal, low-dose intensity from onset to end-exercise in healthy middle-aged participants. Design: Randomized controlled crossover trial. Setting: The participants underwent 1 ECC and 1 CON test according to stepwise incremental exercise protocols at identical, submaximal intensities. Breath-by-breath analyses of ventilatory gas exchange and echocardiography were used to assess cardiopulmonary function during exercise. Participants: 24 healthy middle-aged, untrained participants (14 women, 10 men, 50±14 years) were included. Interventions: 1 ECC and 1 CON test at submaximal intensities. Main Outcome Measure: The main outcome was oxygen uptake (V'O2). Results: The V'O2 increase was reduced by -422 mL/min (-52%, 95% confidence interval: -513 to -292, P<.001) during ECC, as well as the ventilatory drive. Echocardiographic parameters, heart rate (-14%), cardiac output (-21%), stroke volume (-15%), and pulmonary artery pressure by tricuspid regurgitation pressure gradient (TRPG) (-26%) were also significantly reduced during ECC compared with CON at identical intensities. Participants reported significantly less dyspnea and unchanged perceived leg fatigue in ECC. Conclusion: ECC was well tolerated, and significant reductions were observed in V'O2, ventilation, and right ventricular load compared with CON, even at low intensity levels. This study, conducted on healthy middle-aged participants, did not raise concerns that would hinder further investigation of the effects of ECC in patients with severely limited cardiopulmonary disease, and it calls for further research on this topic.