Nagase T; Department of Cardiovascular Surgery, Fukuoka Children’s Hospital, Fukuoka, Japan.
Fujita S; Harada T; Hosoda R; Okamoto K; Oda S; Nakano T;

European journal of cardio-thoracic surgery :
official journal of the European Association for Cardio-thoracic Surgery [Eur J Cardiothorac Surg] 2025 Mar 04; Vol. 67 (3).

Objectives: To examine the outcomes of patients with classical hypoplastic left heart syndrome following extracardiac total cavopulmonary connection.
Methods: We retrospectively analysed 812 cases that underwent extracardiac total cavopulmonary connection at our hospital between 1994 and 2022. With a median follow-up of 10.1 years, we compared the survival rate, Fontan-related events, liver function, postoperative haemodynamics, freedom from reintervention and exercise tolerance in 109 patients with classical hypoplastic left heart syndrome (cH group), 205 patients with heterotaxy (Hx group) and 498 patients with other univentricular conditions (O group).
Results: The survival rates (97.2% at 10 and 20 years for the cH group) and freedom rates from all Fontan-related events (81.2% and 68.1%) were similar across groups. Liver enzyme variables did not significantly differ, and liver cirrhosis was not observed. Postoperative catheter examinations showed similar Fontan pressure, end-diastolic pressure, cardiac index and pulmonary vascular resistance across groups, with a lower pulmonary artery index in the cH group. The rates of freedom from reintervention at 10 and 20 years were lower in the cH group (80.5% and 55.7%). Maximal oxygen consumption during cardiopulmonary exercise testing declined faster in the cH group (-2.5% per year) than in the O group (-0.9% per year), with no difference with the Hx group (-2.4% per year).
Conclusions: The overall survival rate of patients with classical hypoplastic left heart syndrome after Fontan procedure was comparable to that of patients with other univentricular syndromes, showing good haemodynamics and lower mid-term comorbidities. However, lower pulmonary artery index, reduced freedom from reintervention and progressive decline in exercise tolerance are remaining concerns.

Ekström M;  Faculty of Medicine, Lund University, Lund, Sweden.
Li PZ; Lewthwaite H; Bourbeau J; Tan WC; Jensen D;

Chest [Chest] 2025 Mar 11.
Date of Electronic Publication: 2025 Mar 11.

Background: Exertional breathlessness is a cardinal symptom of people with chronic airflow limitation (CAL) and can be evaluated using cardiopulmonary exercise testing (CPET).
Research Question: Does abnormally high exertional breathlessness in relationship to the rate of oxygen uptake (V’O ₂ ) and minute ventilation (V’ _E ) indicate different underlying pathophysiologic mechanisms and clinical characteristics in people with CAL?
Study Design and Methods: Analysis of people ≥ 40 years of age with CAL (FEV ₁ to FVC ratio after bronchodilation less than lower limit of normal) undergoing symptom-limited incremental cycle CPET in the Canadian Cohort Obstructive Lung Disease study. Using published normative references, breathlessness phenotypes at peak exercise were categorized as abnormal (Borg 0-10 scale intensity rating more than upper limit of normal) by V’O ₂ alone, abnormal by both V’O ₂ and V’ _E , or normal by both V’O ₂ and V’ _E . Exercise physiologic responses and clinical characteristics were compared between groups.
Results: We included 325 people (44% women) with CAL (mean (SD) FEV ₁ , 75.4 (17.5)% predicted). Compared with the normal by both V’O ₂ and V’ _E group (n = 237 [73%]), the abnormal by V’O ₂ only group (n = 29 [9%]) showed lower pulmonary diffusing capacity and greater exercise ventilatory inefficiency, whereas the abnormal by both V’O ₂ and V’ _E group (n = 50 [15%]) showed even worse lung function, dynamic critical inspiratory constraints, and exertional breathlessness along with greater symptom burden in daily life, lower physical activity, and worse health status.
Interpretation: Exertional breathlessness phenotyped in relationship to V’O ₂ and V’ _E using normative reference equations enable multivariable analyses of underlying symptom mechanisms and associated clinical characteristics.
Competing Interests: Financial/Nonfinancial Disclosures The authors have reported to CHEST the following: J. B. and W. C. T. report receiving institutional funding for the CanCOLD study from Astra Zeneca Canada, Ltd., Boehringer-Ingelheim Canada, Ltd., GlaxoSmithKline Canada, Ltd., Merck, Novartis Pharma Canada, Inc., as well as Nycomed Canada, Inc. (W. C. T.), Pfizer Canada, Ltd. (W. C. T.), Trudell (J. B.), and Grifolds (J. B.). None declared (M. E., P. Z. L., H. L., D. J.).

O. Inbar, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
O. Inbar, R. Dlin and R. Casaburi

Eur J Appl Physiol 2025 Mar 21

Cardiopulmonary exercise testing (CPET) has emerged as a powerful diagnostic tool, providing comprehensive physiological insights into the integrated function of cardiovascular, respiratory, and metabolic systems. Exploiting physiological interactions, CPET allows in-depth diagnostic insights. CPET performance entrains several complexities. Interpreting CPET data can be challenging, requiring significant physiological expertise. The advent of artificial intelligence (AI) has introduced a transformative approach to CPET interpretation, enhancing accuracy, efficiency, and clinical decision-making. This review article explores the current state of AI applications in CPET, highlighting AI’s potential to replace the traditional stress electrocardiogram (ECG) test as the preferred diagnostic tool in preventive medicine and medical screening. The article discusses the underlying principles of AI, its integration into CPET interpretation, and the associated benefits, including improved diagnostic accuracy, reduced interobserver variability, and expedited decision-making. Additionally, it addresses the challenges and considerations surrounding the implementation of AI in CPET such as data quality, model interpretability, and ethical concerns. The review concludes by emphasizing the significant promise of AI-assisted CPET interpretation in revolutionizing preventive medicine and medical screening settings and enhancing patient care.

Declarations. Conflict of interest: Dr. Omri Inbar is a retired senior lecturer from the Sackler School of Medicine at Tel-Aviv University and is currently the scientific consultant to Medibyt Ltd., external to submitted work. Or Inbar serves as the CEO of Medibyt LTD (Advanced CPET Analysis Platform), which is external to the submitted work. The remaining authors declare no competing interests.

• Stevens JL; Department of Anaesthesia, Royal Sussex County Hospital,  Brighton and Hove, United Kingdom.; and other UK centgres
• McKenna HT; Minnion M; Murray AJ; Feelisch M; Martin DS;

Experimental biology and medicine (Maywood, N.J.) [Exp Biol Med (Maywood)] 2025 Feb 21; Vol. 250, pp. 10254.
Date of Electronic Publication: 2025 Feb 21

Abstract

• More complex surgeries are being performed in increasingly sicker patients, resulting in a greater burden of postoperative morbidity. Delineating the metabolic and bioenergetic changes that occur in response to surgical stress may further our understanding about how humans respond to injury and aid the identification of resilient and frail phenotypes.
  Skeletal muscle biopsies were taken from patients undergoing hepato-pancreatico-biliary surgery at the beginning and end of the procedure to measure mitochondrial respiration and thiol status. Blood samples were taken at the same timepoints to measure markers of inflammation and systemic redox state. A sub-group of patients underwent cardiopulmonary exercise testing prior to surgery, and were assigned to two groups according to their oxygen consumption at anaerobic threshold (≤10 and >10 mL/kg/min) to determine whether redox phenotype was related to cardiorespiratory fitness.
  No change in mitochondrial oxidative phosphorylation capacity was detected. However, a 26.7% increase in LEAK (uncoupled) respiration was seen after surgery (P = 0.03). Free skeletal muscle cysteine also increased 27.0% (P = 0.003), while S-glutathionylation and other sulfur and nitrogen-based metabolite concentrations remained unchanged. The increase in LEAK was 200% greater in fit patients (P = 0.004). Baseline plasma inflammatory markers, including TNF-⍺ and IL-6 were greater in unfit patients, 96.6% (P = 0.04) and 111.0% (P = 0.02) respectively, with a 58.7% lower skeletal muscle nitrite compared to fit patients.
  These data suggest that oxidative phosphorylation is preserved during the acute intraoperative period. Increase in free cysteine may demonstrate the muscle’s response to surgical stress to maintain redox balance. The differences in tissue metabolism between fitness groups suggests underlying metabolic phenotypes of frail and resilient patients. For example, increased LEAK in fitter patients may indicate mitochondrial adaptation to stress. Higher baseline measurements of inflammation and lower tissue nitrite in unfit patients, may reflect a state of frailty and susceptibility to postoperative demise.

• Miao G; China Institute of Sport Science, Beijing, China.;  Shijiazhuang, Hebei, China.
• Yan Q; Zhu H;

Frontiers in physiology [Front Physiol] 2024 Dec 24; Vol. 15, pp. 1437962. Date of Electronic Publication: 2024 Dec 24

• Objective: To explore the feasibility of post-exercise heart rate recovery indicators for predicting maximum oxygen uptake (VO2max) in healthy adults aged 30-60 years.
• Methods: 260 healthy adults who did not perform regular exercise were randomly recruited and divided into a model group (n = 200) and a verification group (n = 60). Measure body fat percentage, weight, height and other indicators, and complete a cardiopulmonary exercise test as required to measure VO2max and heart rate recovery (HRR1, HRR2) in the first and second minutes after exercise. Equations are established through stepwise regression method, and the selected optimal equation is tested for back substitution.
• Results: The optimal equation is: Absolute VO 2 ⁡ max = – 0.528 + 0.039 * weight – 3.463 * body fat rate + 0.042 * HRR 2 – 0.180 * gender male = 1 , female = 2 . Analysis of variance, goodness-of-fit test, VIF test, Shapiro-Wilk test, and Durbin-Watson test indicate that the equation is more reliable; Pearson product-moment correlation analysis, paired t test, and Bland-Altman consistency test indicate that the equation is more valid good.
• Conclusion: The regression equation established through heart rate recovery after exercise can be used to predict VO2max in healthy adults aged 30-60 years.

Badiani, Sveeta; St Bartholomew’s Hospital, Barts Health NHS Trust, London,
van Zalen, Jet; Alborikan, Sahar; Althunayyan, Aeshah; et al

Echo research and practice,2025 Mar 05

• Background: Patients with moderate aortic stenosis (AS) may experience symptoms and adverse outcomes. The aim of this study was to determine whether patients with moderate AS exhibited objective evidence of exercise limitation, compared with age and sex matched controls and if so, to determine which echocardiographic parameters predicted exercise ability.
• Methods: This was a prospective case control study of patients with moderate AS (peak velocity (Vmax) 3.0-3.9 m/s, mean gradient (MG) 20-39mmHg, aortic valve area (AVA)1.1-1.5cm ² ) and left ventricular ejection fraction (LVEF) ≥ 55%. All patients underwent cardiopulmonary stress echocardiography.
• Results: 25 patients with moderate AS (Vmax 3.5 ± 0.2mmHg, mean gradient 28 ± 5mmHg, AVA 1.2 ± 0.1cm ² , LVEF 61 ± 4%) were compared with 25 controls. % predicted oxygen uptake efficiency slope (OUES), % predicted O ₂ pulse and VO ₂ at anaerobic threshold (AT) were significantly lower in patients compared with controls (OUES 79 ± 15 vs. 89 ± 15%, p = 0.013). VO ₂ did not significantly differ between cases and controls.
• Conclusion: Objective measures of exercise capacity including OUES, O ₂ pulse and VO ₂ at AT are significantly lower in patients with moderate AS compared with controls, suggesting that these parameters may be more useful than VO ₂ where patients may be unable to complete a maximal exercise test. Risk stratification using cardiopulmonary exercise echocardiography may help to identify patients with moderate AS who are at increased risk of cardiovascular events and should be considered for more intensive surveillance and intervention.
• Trial Registration: Clinical trial number MRC 0225 IRAS 207395.

Genecand, Léon; Service de Pneumologie,  Hôpitaux Universitaires de Genève, Genève, Switzerland.;
Jaksic, Cyril; Desponds, Roberto; Simian, Gaëtan; et al

Physiological reports,2025 Mar

• he dispersion of the tidal volume and of the breathing frequency have been used to diagnose dysfunctional breathing during cardio-pulmonary exercise testing. No validated methods to objectively describe this dispersion exist. We aimed to validate such a method. We used simulations based on real-life parameters. Moving standard deviation (MSD) and residuals from locally estimated scatterplot smoothing (LOESS) were evaluated. The precision and the bias of each tested method at rest and during exercise simulations, with and without sighs, were measured. For LOESS, a 2nd degree polynomial was used, and different spans were tested (LOESS ₁ , LOESS _0.75 , and LOESS _0.5 ). For MSD, different number of points used for the calculation were tested (MSD ₇ , MSD ₁₁ , MSD ₁₅ , and MSD19). The LOESS method was globally more precise, had less bias, and was less influenced by the trend as compared to MSD in almost all simulations except for extremely low dispersion combined with extreme trends. LOESS _0.75 had intermediate bias and precision between LOESS _0.5 and LOESS ₁ in all simulations. LOESS _0.75 is a method that combines high precision, low bias, and low influenceability of trends. It could be considered as the method of choice to evaluate the dispersion of breathing parameters during cardiopulmonary exercise testing.
• (© 2025 The Author(s). Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Souilla, Luc; Department of Pediatric and Congenital Cardiology, Montpellier University Hospital, France
Werner, Oscar; Huguet, Helena; et al

JAMA Network Open,25/02/2025

• Key Points: Question: What are the levels of cardiopulmonary fitness among children and adolescents with inherited cardiac disease compared with healthy controls and the factors associated with maximum oxygen uptake (V̇o₂ max) in young patients? Findings: This cross-sectional study with 207 participants showed lower levels of cardiopulmonary fitness among youths with inherited cardiac disease. The multivariable model explained 80% of V̇o₂ max, including clinical, functional, sociodemographic, and behavioral parameters. Meaning: This study suggests that assessing cardiopulmonary fitness among children with inherited cardiac disease can be incorporated into the shared decision-making process for sports participation and may help identify eligible patients for early preventive cardiac rehabilitation programs. Importance: Historical restrictions on children with inherited cardiac arrhythmia or cardiomyopathy have been implemented to mitigate the potential risk of sudden death, but these limitations can be detrimental to overall health and cardiopulmonary fitness.
  Objectives: To evaluate cardiopulmonary fitness and physical activity among children with inherited cardiac disease and identify the factors associated with maximum oxygen uptake (V̇o₂ max) in this population.
  Design, Setting, and Participants: This cross-sectional, multicenter, prospective controlled study was conducted in 7 tertiary care expert centers for inherited cardiac disease in France from February 1, 2021, to June 20, 2023, with a 2-week follow-up. Participants included 100 children and adolescents aged 6 to 17 years with inherited cardiac arrhythmia or cardiomyopathy who were compared with 107 sex- and age-matched controls.
  Main Outcomes and Measures: Maximum oxygen uptake was assessed using cardiopulmonary exercise testing, and results were expressed using pediatric reference z score values. The main determinants of V̇o₂ max included clinical (New York Heart Association [NYHA] functional class, treatment, echocardiographic, and electrocardiogram variables), functional (cardiopulmonary exercise test parameters), sociodemographic (sex, schooling, and parents’ education), and behavioral (physical activity and motivation) characteristics. Results: A total of 100 patients (mean [SD] age, 12.7 [3.1] years; 52 boys [52.0%]) and 107 controls (mean [SD] age, 11.7 [3.3] years; 54 boys [50.5%]) were included. The V̇o₂ max was lower in patients than controls, expressed as z scores (mean [SD] score, −1.49 [1.48] vs −0.16 [0.97]; P <.001) or raw values (mean [SD] value, 32.2 [7.9] vs 40.2 [8.5] mL/kg/min; P <.001). Moderate to vigorous physical activity levels were lower in patients than in controls (mean [SD] level, 42.0 [23.6] vs 48.2 [20.4] min/d; P =.009). The final multivariable model explained 80% of the V̇o₂ max by integrating clinical (lower NYHA functional class, absence of ventricular dilatation, and absence of implantable cardioverter-defibrillator), functional (higher forced vital capacity and ventilatory anaerobic threshold), sociodemographic (male sex, normal progression of schooling, and higher maternal educational level), and behavioral (higher self-reported physical activity and motivation toward physical activity) parameters.
  Conclusions and Relevance: This cross-sectional study suggests that levels of cardiopulmonary fitness and physical activity were lower in children and adolescents with inherited cardiac disease than in healthy controls, even after adjusting for use of β-blockers and using modern pediatric reference models. Assessing cardiopulmonary fitness among children with inherited cardiac disease can contribute to engaging in a shared decision-making process for sports participation and preventive interventions, such as early cardiac rehabilitation programs. This cross-sectional study evaluates cardiopulmonary fitness and physical activity among children with inherited cardiac disease vs controls and identifies the factors associated with maximum oxygen uptake in this population.

Joosen, Renée S; Department of Pediatric Cardiology, University Medical Center Utrecht,  the Netherlands.
Voskuil, Michiel;de Pater, Wieke G;Wijk, Sebastiaan W H van;

International journal of cardiology. Congenital heart disease,2025 Feb 15

• Background: Patients with transposition of the great arteries (TGA) experience reduced exercise capacity after the arterial switch operation (ASO), possibly due to limited stroke volume. This study evaluates the role of stroke volume in reduced exercise capacity in these patients.
• Methods: A retrospective analysis was conducted on TGA patients who underwent a transthoracic echocardiogram (TTE), cardiac magnetic resonance (CMR) and cardiopulmonary exercise test (CPET) within one year between September 2009 and February 2024 at the University Medical Center Utrecht. Excluding those with submaximal CPET results, the remaining patients were divided into <18 and ≥ 18 years old groups. Reduced exercise capacity was defined as a peak oxygen uptake (VO ² peak) with a Z-score < -2. Left and right ventricular (LV and RV) data including volumes, function, strain and RV outflow tract obstructions were collected from TTE and CMR.
• Results: A total of 126 patients (72 % male, mean age 19 ± 8 years) were included. Left ventricular function, RV volumes, function and strain were relatively preserved on CMR. Reduced VO ² peak was seen in 55 % of patients ≥18 years, significantly more than those <18 years (23 %, p < 0.001). Reduced VO ² peak was independently associated with time since ASO, body mass index, peak heat rate (HRpeak), and O ² pulse. VO ² peak showed weak to moderate correlations with time after ASO (R = -0.295,p < 0.001), body mass index (R = -0.468,p < 0.001) and HRpeak (R = 0.270,p = 0.002) and a strong correlation with O ² pulse (R = 0.621,p < 0.001).
• Conclusion: Exercise capacity in TGA patients after ASO might be limited by an impaired ability to increase stroke volume.
• Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: J.M.P.J. Breur reports financial support was provided by Netherlands Heart Foundation. J.M.P.J. Breur reports financial support was provided by Stichting Hartekind. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Bomma, Meghana; Department of Physiology and Aging, University of Florida, Gainesville, FL, USA.
Lott, Donovan;Forbes, Sean;Shih, Renata; et al

Journal of neuromuscular diseases,2025 Mar 04

• Background: Cardiopulmonary exercise testing (CPET) is the gold-standard for quantification of peak oxygen uptake (VO ₂ ) and cardiorespiratory and muscle responses to exercise. Its application to Duchenne muscular dystrophy (DMD) has been scarce due to the notion that muscle weakness inherent to disease restricts the cardiorespiratory system from reaching maximal capacity.
• Objective: To investigate the utility of CPET in DMD by 1) establishing whether patients can perform maximal-effort exercise for valid VO ₂ peak assessment; 2) quantifying VO ₂ peak repeatability; 3) characterizing muscle and cardiorespiratory responses; 4) comparing VO ₂ peak to 6-min walk distance (6MWD).
• Methods: Twenty-seven DMD and eight healthy boys (6 years and older) underwent CPET using an incremental work-rate protocol for leg (ambulatory) or arm (non-ambulatory) cycling with measurement of heart rate (HR) and gas-exchange variables from rest to maximal-effort. The oxygen cost of work (ΔVO ₂ /Δwork-rate) was calculated, and peak exercise parameters (VO ₂ , HR, O ₂ pulse, ventilation (VE) and ventilatory threshold (VT)) were considered valid if the respiratory exchange ratio ≥1.01.
• Results: VO ₂ peak was valid (81.5% of patients), repeatable (intraclass correlation coefficient = 0.998) and low in ambulatory and non-ambulatory DMD compared to controls (19.0 ± 6.0; 10.7 ± 2; 35.2 ± 4.5 mL/kg/min respectively). VT was low (30.8 ± 10.7; 19.4 ± 3.0; 61.2 ± 6.9% VO ₂ peak) reflecting significant muscle metabolic impairment. Peak HR in ambulatory-DMD (172 ± 14 bpm) was similar to controls (183 ± 8.3 bpm), but O ₂ pulse was low (3.4 ± 1.0; 6.5 ± 1.1 mL/beat). Peak VE/VO ₂ (ambulatory = 42.1 ± 6.8; non-ambulatory = 42.2 ± 7.8; controls = 34.3 ± 4.6) and ΔVO ₂ /Δwork-rate were elevated (ambulatory = 12.4 ± 4.9; non-ambulatory = 19.0 ± 9.7; controls = 10.1 ± 0.8) revealing ventilatory and mechanical inefficiency. Despite strong correlation between VO ₂ peak and 6MWD, severity of impairment was discordant.
• Conclusion: Valid CPET is feasible in DMD, revealing low VO ₂ peak due to abnormal muscle metabolic and cardiorespiratory responses during dynamic exercise. CPET reveals cardiorespiratory limitations in DMD boys with unremarkable 6MWD, and should be considered an integrative approach in clinical care and assessment of emerging therapeutics.