Category Archives: Abstracts

Exercise oscillatory ventilation: the past, present, and future

G. Cunha, A. Apostolo, F. De Martino, E. Salvioni, I. Matavelli and P. Agostoni

Eur J Prev Cardiol 2023 Vol. 30 Issue Suppl 2 Pages ii22-ii27

Exercise oscillatory ventilation (EOV) is a fascinating event that can be appreciated in the cardiopulmonary exercise test and is characterized by a cyclic fluctuation of minute ventilation, tidal volume, oxygen uptake, carbon dioxide production, and end-tidal pressure for oxygen and carbon dioxide. Its mechanisms stem from a dysregulation of the normal control feedback of ventilation involving one or more of its components, namely, chemoreflex delay, chemoreflex gain, plant delay, and plant gain. In this review, we intend to breakdown therapeutic targets according to pathophysiology and revise the prognostic value of exercise oscillatory ventilation in the setting of heart failure and other diagnoses.

Two is better than one: the double diffusion technique in classifying heart failure

Zavorsky, G;  Agostoni, P;

ERJ Open Res 2024 Vol. 10 Issue 1

BACKGROUND: Heart failure (HF) is a chronic condition in which the heart does not pump enough blood to meet the body’s demands. Diffusing capacity of the lung for nitric oxide (D(LNO)) and carbon monoxide (D(LCO)) may be used to classify patients with HF, as D(LNO) and D(LCO) are lung function measurements that reflect pulmonary gas exchange. Our objectives were to determine 1) if D(LNO) added to D(LCO) testing predicts HF better than D(LCO) alone and 2) whether the binary classification of HF is better when D(LNO) z-scores are combined with D(LCO) z-scores than using D(LCO) z-scores alone.
METHODS: This was a retrospective secondary data analysis in 140 New York Heart Association Class II HF patients (ejection fraction <40%) and 50 patients without HF. z-scores for D(LNO), D(LCO) and D(LNO)+D(LCO) were created from reference equations from three articles. The model with the lowest Bayesian Information Criterion was the best predictive model. Binary HF classification was evaluated with the Matthews Correlation Coefficient (MCC). RESULTS: The top two of 12 models were combined z-score models. The highest MCC (0.51) was from combined z-score models. At most, only 32% of the variance in the odds of having HF was explained by combined z-scores.
CONCLUSIONS: Combined z-scores explained 32% of the variation in the likelihood of an individual having HF, which was higher than models using D(LNO) or D(LCO) z-scores alone. Combined z-score models had a moderate ability to classify patients with HF. We recommend using the NO-CO double diffusion technique to assess gas exchange impairment in those suspected of HF.

What about chronotropic incompetence in heart failure with mildly reduced ejection fraction? Clinical and prognostic implications from the Metabolic Exercise combined with Cardiac and Kidney Indexes score dataset

D. Magri, G. Gallo, M. Piepoli, E. Salvioni, M. Mapelli, C. Vignati, et al.

Eur J Prev Cardiol 2024 Vol. 31 Issue 2 Pages 263-271

AIMS: Chronotropic incompetence (CI) is a strong predictor of outcome in heart failure with reduced ejection fraction, however no data on its clinical and prognostic impacts in heart failure with mildly reduced ejection fraction (HFmrEF) are available. Therefore, the study aims to investigate, in a large multicentre HFmrEF cohort, the prevalence of CI as well as its relationship with exercise capacity and its prognostic role over the cardiopulmonary exercise testing (CPET) parameters.
METHODS AND RESULTS: Within the Metabolic Exercise combined with Cardiac and Kidney Indexes (MECKI) database, we analysed data of 864 HFmrEF out of 1164 stable outpatients who performed a maximal CPET at the cycle ergometer and who had no significant rhythm disorders or comorbidities. The primary study endpoint was cardiovascular (CV) death. All-cause death was also explored. Chronotropic incompetence prevalence differed depending on the method (peak heart rate, pHR% vs. pHR reserve, pHRR%) and the cut-off adopted (pHR% from </=75% to </=60% and pHRR% </= 65% to </=50%), ranging from 11% to 62%. A total of 84 (9.7%) CV deaths were collected, with 39 (4.5%) occurring within 5 years. At multivariate analysis, both pHR% [hazard ratio 0.97 (0.95-0.99), P < 0.05] and pHRR% [hazard ratio 0.977 (0.961-0.993), P < 0.01] were associated with the primary endpoint. A pHR% </= 75% and a pHRR% </= 50% represented the most accurate cut-off values in predicting the outcome.
CONCLUSION: The study suggests an association between blunted exercise-HR response, functional capacity, and CV death risk among patients with HFmrEF. Whether the CI presence might be adopted in daily HFmrEF management needs to be addressed in larger prospective studies.
Chronotropic incompetence is an easy-to-obtain additive parameter for cardiovascular death risk stratification in heart failure with mildly reduced ejection fraction (HFmrEF). Peak heart rate and peak heart rate reserve are associated with exercise capacity in HFmrEF. Peak heart rate and peak heart rate reserve are associated with cardiovascular death in HFmrEF.

Using Machine Learning-Based Algorithms to Identify and Quantify Exercise Limitations in Clinical Practice: Are We There Yet?

Med Sci Sports Exercise 2024 Feb 1;56(2):159-169

Introduction: Well-trained staff is needed to interpret cardiopulmonary exercise tests (CPET). We aimed to examine the accuracy of machine learning-based algorithms to classify exercise limitations and their severity in clinical practice compared with expert consensus using patients presenting at a pulmonary clinic.

Methods: This study included 200 historical CPET data sets (48.5% female) of patients older than 40 yr referred for CPET because of unexplained dyspnea, preoperative examination, and evaluation of therapy progress. Data sets were independently rated by experts according to the severity of pulmonary-vascular, mechanical-ventilatory, cardiocirculatory, and muscular limitations using a visual analog scale. Decision trees and random forests analyses were calculated.

Results: Mean deviations between experts in the respective limitation categories ranged from 1.0 to 1.1 points (SD, 1.2) before consensus. Random forests identified parameters of particular importance for detecting specific constraints. Central parameters were nadir ventilatory efficiency for CO 2 , ventilatory efficiency slope for CO 2 (pulmonary-vascular limitations); breathing reserve, forced expiratory volume in 1 s, and forced vital capacity (mechanical-ventilatory limitations); and peak oxygen uptake, O 2 uptake/work rate slope, and % change of the latter (cardiocirculatory limitations). Thresholds differentiating between different limitation severities were reported. The accuracy of the most accurate decision tree of each category was comparable to expert ratings. Finally, a combined decision tree was created quantifying combined system limitations within one patient.

Conclusions: Machine learning-based algorithms may be a viable option to facilitate the interpretation of CPET and identify exercise limitations. Our findings may further support clinical decision making and aid the development of standardized rating instruments.

Accelerometer Metrics: Healthy Adult Reference Values, Associations with Cardiorespiratory Fitness, and Clinical Implications

Med Sci Sports Exercise 2024 Feb 1;56(2):170-180.

Purpose: Accelerometer-assessed physical activity (PA) can be summarized using cut-point-free or population-specific cut-point-based outcomes. We aimed to 1) examine the interrelationship between cut-point-free (intensity gradient (IG) and average acceleration (AvAcc)) and cut-point-based accelerometer metrics, 2) compare the association between cardiorespiratory fitness (CRF) and cut-point-free metrics to that with cut-point-based metrics in healthy adults aged 20 to 89 yr and patients with heart failure, and 3) provide age-, sex-, and CRF-related reference values for healthy adults.

Methods: In the COmPLETE study, 463 healthy adults and 67 patients with heart failure wore GENEActiv accelerometers on their nondominant wrist and underwent cardiopulmonary exercise testing. Cut-point-free (IG: distribution of intensity of activity across the day; AvAcc: proxy of volume of activity) and traditional (moderate-to-vigorous and vigorous activity) metrics were generated. The “interpretablePA” R-package was developed to translate findings into clinical practice.

Results: IG and AvAcc yield complementary information on PA with both IG ( P = 0.009) and AvAcc ( P < 0.001) independently associated with CRF in healthy individuals (adjusted R2 = 73.9%). Only IG was independently associated with CRF in patients with heart failure ( P = 0.043, adjusted R2 = 38.4%). The best cut-point-free and cut-point-based model had similar predictive value for CRF in both cohorts. We produced age- and sex-specific reference values and percentile curves for IG, AvAcc, moderate-to-vigorous PA, and vigorous PA for healthy adults.

Conclusions: IG and AvAcc are strongly associated with CRF and thus indirectly with the risk of noncommunicable diseases and mortality, in healthy adults and patients with heart failure. However, unlike cut-point-based metrics, IG and AvAcc are comparable across populations. Our reference values provide a healthy age- and sex-specific comparison that may enhance the translation and utility of cut-point-free metrics in clinical practice.


A verification phase adds little value to the determination of maximum oxygen uptake in well-trained adults

Eur J Appl Physiol 2024 Jan 18

Purpose: The objective was to investigate if performing a sub-peak or supra-peak verification phase following a ramp test provides additional value for determining ‘true’ maximum oxygen uptake ([Formula: see text]O2).

Methods: 17 and 14 well-trained males and females, respectively, performed two ramp tests each followed by a verification phase. While the ramp tests were identical, the verification phase differed in power output, wherein the power output was either 95% or 105% of the peak power output from the ramp test. The recovery phase before the verification phase lasted until capillary blood lactate concentration was ≤ 4 mmol·L-1. If a [Formula: see text]O2 plateau occurred during ramp test, the following verification phase was considered to provide no added value. If no [Formula: see text]O2 plateau occurred and the highest [Formula: see text]O2 ([Formula: see text]O2peak) during verification phase was < 97%, between 97 and 103%, or > 103% of [Formula: see text]O2peak achieved during the ramp test, no value, potential value, and certain value were attributed to the verification phase, respectively.

Results: Mean (standard deviation) [Formula: see text]O2peak during both ramp tests was 64.5 (6.0) mL·kg-1·min-1 for males and 54.8 (6.2) mL·kg-1·min-1 for females. For the 95% verification phase, 20 tests showed either a [Formula: see text]O2 plateau during ramp test or a verification [Formula: see text]O2peak < 97%, indicating no value, 11 showed potential value, and 0 certain value. For the 105% verification phase, the values were 26, 5, and 0 tests, respectively.

Conclusion: In well-trained adults, a sub-peak verification phase might add little value in determining ‘true’ maximum [Formula: see text]O2, while a supra-peak verification phase adds no value.

Autonomic dysfunction and exercise intolerance in post-COVID-19 – An as yet underestimated organ system?

Schwendinger, F; University Basel | Departement for Sport, Exercise and Health (DSBG), Switzerland
Looser, V; Gerber, M; Schmidt-Trucksass;

Int J Clin Health Psychol. 2024 Jan-Mar; 24(1):100429

Individuals recovering from COVID-19 often present with persistent symptoms, particularly exercise intolerance and low cardiorespiratory fitness. Put simply, the Wasserman gear system describes the interdependence of heart, lungs, and musculature as determinants of cardiorespiratory fitness. Based on this system, recent findings indicate a contribution of peripheral, cardiovascular, and lung diffusion limitations to persistent symptoms of exercise intolerance and low cardiorespiratory fitness. The autonomic nervous system as an organ system involved in the pathophysiology of exercise intolerance and low cardiorespiratory fitness, has received only little attention as of yet. Hence, our article discusses contribution of the autonomic nervous system through four potential pathways, namely alterations in (1) cerebral hemodynamics, (2) afferent and efferent signaling, (3) central hypersensitivity, and (4) appraisal and engagement in physical activity. These pathways are summarized in a psycho-pathophysiological model. Consequently, this article encourages a shift in perspective by examining the state of the pulmonary and cardiovascular system, the periphery, and auxiliary, the autonomic nervous system as potential underlying mechanisms for exercise intolerance and low cardiorespiratory fitness in patients with post-COVID-19.


Preoperative aerobic fitness and perioperative outcomes in patients undergoing cystectomy before and after implementation of a national lockdown.

Tetlow N; Department of Anaesthesia and Peri-operative Medicine, University College London Hospitals
Dewar A; Arina P; Tan M; Sridhar AN; Kelly JD; Arulkumaran N; Stephens RCM; London, UK.; Martin DS; Moonesinghe SR; Whittle J;

BJA open [BJA Open] 2024 Jan 17; Vol. 9, pp. 100255.
Date of Electronic Publication: 2024 Jan 17 (Print Publication: 2024).

Background: Lower fitness is a predictor of adverse outcomes after radical cystectomy. Lockdown measures during the COVID-19 pandemic affected daily physical activity. We hypothesised that lockdown during the pandemic was associated with a reduction in preoperative aerobic fitness and an increase in postoperative complications in patients undergoing radical cystectomy.
Methods: We reviewed routine preoperative cardiopulmonary exercise testing (CPET) data collected prior to the pandemic (September 2018 to March 2020) and after lockdown (March 2020 to July 2021) in patients undergoing radical cystectomy. Differences in CPET variables, Postoperative Morbidity Survey (POMS) data, and length of hospital stay were compared.
Results: We identified 267 patients (85 pre-lockdown and 83 during lockdown) who underwent CPET and radical cystectomy. Patients undergoing radical cystectomy throughout lockdown had lower ventilatory anaerobic threshold (9.0 [7.9-10.9] vs 10.3 [9.1-12.3] ml kg -1 min -1 ; P =0.0002), peak oxygen uptake (15.5 [12.9-19.1] vs 17.5 [14.4-21.0] ml kg -1 min -1 ; P =0.015), and higher ventilatory equivalents for carbon dioxide (34.7 [31.4-38.5] vs 33.4 [30.5-36.5]; P =0.030) compared with pre-lockdown. Changes were more pronounced in males and those aged >65 yr. Patients undergoing radical cystectomy throughout lockdown had a higher proportion of day 5 POMS-defined morbidity (89% vs 75%, odds ratio [OR] 2.698, 95% confidence interval [CI] 1.143-6.653; P =0.019), specifically related to pulmonary complications (30% vs 13%, OR 2.900, 95% CI 1.368-6.194; P =0.007) and pain (27% vs 9%, OR 3.471, 95% CI 1.427-7.960; P =0.004), compared with pre-lockdown on univariate analysis.
Conclusions: Lockdown measures in response to the COVID-19 pandemic were associated with a reduction in fitness and an increase in postoperative morbidity among patients undergoing radical cystectomy.

Reduced exercise capacity for muscle mass in adolescents living with obesity.

Colapelle J; Experimental Medicine, McGill University Experimental Medicine, Montréal, Quebec, Canada.
St-Pierre J; Erdstein J; Lands LC;

Pediatric pulmonology [Pediatr Pulmonol] 2024 Jan 31.
Date of Electronic Publication: 2024 Jan 31.

Background: Adolescents living with obesity (AlwO) can have limited exercise capacity. Exercise capacity can be predicted by a 2-factor model comprising lung function and leg muscle function, but no study has looked at cycling leg muscle function and its contribution to cycling exercise capacity in AlwO.
Methods: Twenty-two nonobese adolescents and 22 AlwO (BMI > 95 percentile) were studied. Anthropometry, body composition (dual-energy X-ray absorptiometry), spirometry, 30-s isokinetic work capacity, and maximal exercise (cycle ergometry) were measured.
Results: AlwO had greater total body mass, lean body mass, and lean leg mass (LLM). Lung function trended higher in AlwO. Leg 30-s work did not differ in absolute terms or per allometrically scaled LLM. Peak oxygen consumption did not differ between the groups in absolute terms or as percent predicted values (79.59 ± 14.6 vs. 82.3 ± 11.2% predicted control versus ALwO) but was lower in AlwO when expressed per kg body mass, kg lean body mass, scaled lean body mass, and LLM. Peak oxygen consumption related to both lung function and 30-s work, with no observed group effect. 30-s leg work related to the scaled LLM, with a small group effect. There was some correlation between leg work and time spent in moderate to vigorous physical activity in AlwO (r s  = 0.39, p = .07).
Conclusion: AlwO have larger LLM and preserved exercise capacity, when expressed as percentage of predicted, but not per allometrically scaled LLM. Increasing time spent in moderate to vigorous activity may benefit AlwO.

Effect of ubiquinol on electrophysiology during high-altitude acclimatization and de-acclimatization: A substudy of the Shigatse CARdiorespiratory fitness (SCARF) randomized clinical trial.

Liu Z; The Second Affiliated Hospital, Army Medical University (Third Military Medical University), Chongqing, PR China.
Yang J; Yang B; Sun M; Ye X; Yu S; Tan H; Hu M; Lv H; Wu B; Gao X; Huang L

International journal of cardiology [Int J Cardiol] 2024 Feb 01, pp. 131817.
Date of Electronic Publication: 2024 Feb 01.

Background: High-altitude exposure changes the electrical conduction of the heart. However, reports on electrocardiogram (ECG) characteristics and potent prophylactic agents during high-altitude acclimatization and de-acclimatization are inadequate. This study aimed to investigate the effects of ubiquinol on electrophysiology after high-altitude hypoxia and reoxygenation.
Methods: The study was a prospective, randomized, double-blind, placebo-controlled trial. Forty-one participants were randomly divided into two groups receiving ubiquinol 200 mg daily or placebo orally 14 days before flying to high altitude (3900 m) until the end of the study. Cardiopulmonary exercise testing was performed at baseline (300 m), on the third day after reaching high altitude, and on the seventh day after returning to baseline.
Results: Acute high-altitude exposure prolonged resting ventricular repolarization, represented by increased corrected QT interval (455.9 ± 23.4 vs. 427.1 ± 19.1 ms, P < 0.001) and corrected T peak -T end interval (155.5 ± 27.4 vs. 125.3 ± 21.1 ms, P < 0.001), which recovered after returning to low altitude. Ubiquinol supplementation shortened the hypoxia-induced extended T peak -T end interval (-7.7 ms, [95% confidence interval (CI), -13.8 to -1.6], P = 0.014), T peak -T end /QT interval (-0.014 [95% CI, -0.027 to -0.002], P = 0.028), and reserved maximal heart rate (11.9 bpm [95% CI, 3.2 to 20.6], P = 0.013) during exercise at high altitude. Furthermore, the decreased resting amplitude of the ST-segment in the V3 lead was correlated with decreased peak oxygen pulse (R = 0.713, P < 0.001) and maximum oxygen consumption (R = 0.595, P < 0.001).
Conclusions: Our results illustrated the electrophysiology changes during high-altitude acclimatization and de-acclimatization. Similarly, ubiquinol supplementation shortened the prolonged T peak -T end interval and reserved maximal heart rate during exercise at high altitude.