Design and validation of an interpretative strategy for cardiopulmonary exercise tests

Quantification of breathing irregularity for the diagnosis of dysfunctional breathing using proportional tidal volume variation: a cross-sectional, retrospective real-world study

OBJECTIVES

To develop a statistical approach that provides a quantitative index measuring the magnitude of the irregularity of the breathing response to exercise for the diagnosis of dysfunctional breathing.

DESIGN

Cross-sectional, retrospective, real-world study.

SETTING

Single-centre study.

PARTICIPANTS

A population of 209 patients investigated with cardiopulmonary exercise testing in our institution for unexplained or disproportionate exertional dyspnoea between January and July 2022.

PRIMARY AND SECONDARY OUTCOME MEASURES

A novel statistical approach providing a quantitative index-proportional tidal volume variation (PTVV)-was developed to measure the magnitude of the irregularity of the breathing response to exercise.

RESULTS

PTVV provided a reliable statistical readout for the objective assessment of DB with a prediction accuracy of 78% (95% CI: 72 to 83%). The prevalence of DB in the investigated population was high with more than half of the patients affected by moderate-to-severe DB.

CONCLUSIONS

PTVV can easily be implemented in the clinical routine. Our study suggests a possible further simplification for the diagnosis of DB with two objective criteria including PTVV and one single criterion for hyperventilation.

Efficacy of Dialectical Comprehensive Treatment of Traditional Chinese Medicine in Patients with Chronic Stable Heart Failure: A Randomized Controlled Trial

The treatment of chronic stable heart failure (CSHF) with integrated traditional Chinese and Western medicine has been of wide concern. We mainly discuss the clinical efficacy of TCM decoction combined with acupuncture and moxibustion (A&M) in CSHF treatment on the basis of syndrome differentiation and treatment (SDT). The control group was given conventional cardiac rehabilitation (CCR), and the treatment group was given TCM decoction combined with A&M treatment based on SDT on the basis of conventional cardiac rehabilitation. The clinical efficacy and cardiopulmonary exercise testing (CPET) indicators were evaluated. Left ventricular ejection fraction (LVEF), NT-proBNP, myocardial ischemia threshold (MIT), and 6-minute walking distance (6MWD) were measured by ultrasound, ELISA, electrocardiogram, and 6MWD test. After treatment, the clinical efficacy, LVEF, and 6MWD of the treatment group were better than in the control group. The NT-proBNP plasma level and MIT in the treatment group were lower than in the control group. The treatment group had enhanced AT, VO2 Peak, VO2 Peak/HR, and Peak power and decreased resting systolic pressure and peak systolic pressure, and the difference was statistically significant. Dialectical comprehensive treatment of TCM could effectively improve cardiac function and clinical treatment effect, which was worthy of clinical application.

Estimating VO2peak in 18–90 Year-Old Adults: Development and Validation of the FitMáx©-Questionnaire

Purpose

Cardiorespiratory fitness (CRF) plays an essential role in health outcomes and quality of life. However, it is often not assessed nor estimated. Objective CRF assessment is costly, labour intensive and not widely available. Patient-reported outcome measures estimate CRF more cost-efficiently, but current questionnaires lack accuracy. The aim of this study is to develop a new self-reported questionnaire to estimate CRF.

Materials and Methods

The FitMáx©-questionnaire, consisting of only three questions assessing walking, stair climbing, and cycling capacity, was compared with the commonly used Duke Activity Status Index (DASI) and Veterans Specific Activity Questionnaire (VSAQ). These questionnaires were compared to peak oxygen uptake (VO_2peak) as measured with cardiopulmonary exercise testing. This study included 759 cardiac, pulmonary and oncologic patients and healthy persons aged 18‒90.

Results

FitMáx© strongly correlated (r = 0.94 (0.92‒0.95) SEE = 4.14 mL∙kg⁻¹∙min⁻¹) with measured VO_2peak. Bias between predicted and measured VO_2peak was −0.24 (−9.23‒8.75; 95% limits of agreement) mL·kg⁻¹·min⁻¹. The FitMáx© scored superiorly on correlation and SEE compared with the DASI and VSAQ, r = 0.75 (0.68‒0.80) SEE = 4.62 mL∙kg⁻¹∙min⁻¹ and r = 0.87 (0.83‒0.90) SEE = 6.75 mL∙kg⁻¹∙min⁻¹, respectively.

Conclusion

FitMáx© is a valid and accessible questionnaire to estimate CRF expressed as VO_2peak in clinical practice and shows substantial improvement compared to currently used questionnaires.

Exercise capacity-impairment after COVID-19 pneumonia is mainly caused by deconditioning

Not pulmonary factors, but physical deconditioning is the main limiting factor of exercise capacity in patients after severe COVID-19 pneumonitis. This underscores the importance of an early rehabilitative intervention in these patients.https://bit.ly/2XVvr6C

A Machine Learning Approach to the Interpretation of Cardiopulmonary Exercise Tests: Development and Validation

Objective

At present, there is no consensus on the best strategy for interpreting the cardiopulmonary exercise test's (CPET) results. This study is aimed at assessing the potential of using computer-aided algorithms to evaluate CPET data for identifying chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD).

Methods

Data from 234 CPET files from the Pulmonary Institute, at Sheba Medical Center, and the Givat-Washington College, both in Israel, were selected for this study. The selected CPET files included patients with confirmed primary CHF (n = 73), COPD (n = 75), and healthy subjects (n = 86). Of the 234 CPETs, 150 (50 in each group) tests were used for the support vector machine (SVM) learning stage, and the remaining 84 tests were used for the model validation. The performance of the SVM interpretive module was assessed by comparing its interpretation output with the conventional clinical diagnosis using distribution analysis.

Results

The disease classification results show that the overall predictive power of the proposed interpretive model ranged from 96% to 100%, indicating very high predictive power. Furthermore, the sensitivity, specificity, and overall precision of the proposed interpretive module were 99%, 99%, and 99%, respectively.

Conclusions

The proposed new computer-aided CPET interpretive module was found to be highly sensitive and specific in classifying patients with CHF or COPD, or healthy. Comparable modules may well be applied to additional and larger populations (pathologies and exercise limitations), thereby making this tool powerful and clinically applicable.

Increased physiological dead space at exercise is a marker of mild pulmonary or cardiovascular disease in dyspneic subjects

Background: The characteristics of cardiopulmonary exercise testing (CPET)-derived parameters for the differential diagnosis of exertional dyspnea are not well known.

Objectives: We hypothesized that increased physiological dead space ventilation (VD/Vt) is a marker for mild pulmonary or cardiovascular disease in patients with exertional dyspnea.

Design: We used receiver operating characteristic analysis to determine the performance of individual CPET parameters for identifying subjects with either mild pulmonary or cardiovascular disease, among 77 subjects with mild-to-moderate exertional dyspnea (modified Medical Research Council scale 1–2).

Results: In comparison with subjects without disease, subjects with pulmonary disease (n = 31) had higher VE/V′CO₂ slope, higher VD/Vt, and lower ventilatory reserve. Subjects with cardiovascular disease (n = 14) had lower heart rate and cardiovascular double product and higher VD/Vt at peak exercise. At a threshold of 28%, the sensitivity and specificity of VD/Vt at peak exercise for identifying pulmonary or cardiovascular disease were 89% (95% CI: 64–98%) and 72% (95% CI: 46–89%), respectively.

Conclusions: Increased physiological VD/Vt at exercise is a sensitive and specific marker of mild pulmonary or cardiovascular disease in dyspneic subjects.

B-type natriuretic peptide and C-terminal-pro-endothelin-1 for the prediction of severely impaired peak oxygen consumption

OBJECTIVE

To assess the utility of B-type natriuretic peptide (BNP) and C-terminal-pro-endothelin-1 (CT-proET-1) to predict a severely impaired peak oxygen consumption (peak VO(2), < 14 mL kg(-1) min(-1)) in patients referred for cardiopulmonary exercise testing.

DESIGN

Cross-sectional study.

SETTING

Tertiary care center.

METHODS

Peak VO(2), BNP and CT-proET-1 were assessed in 141 consecutive patients referred for cardiopulmonary exercise testing.

RESULTS

B-type natriuretic peptide [median (interquartile range) 48 (38-319) vs. 33 (15-86) pg mL(-1); P = 0.002] and CT-proET-1 [87 (76-95) vs. 60 (52-74) pmol L(-1); P < 0.001] were higher in patients with a peak VO(2) < 14 mL kg(-1) min(-1) (n = 30) than in those with a peak VO(2) > or = 14 mL kg(-1) min(-1) (n = 111). CT-pro-ET-1 had a higher area under the receiver-operator-characteristics curve (AUC) to predict a peak VO(2) < 14 mL kg(-1) min(-1) than BNP (0.79 vs. 0.68; P = 0.04). The optimal BNP cut-off of 37.2 pg mL(-1) had a sensitivity of 80% and a specificity of 56%. The optimal CT-proET-1 cut-off of 74.4 pmol L(-1) had a sensitivity of 80% and specificity of 76%. A five-item score composed of body mass index, diabetes, forced expiratory volume within the first second, alveolo-arterial oxygen pressure difference, and BNP had an AUC of 0.88 to predict a peak VO(2) < 14 mL kg(-1) min(-1). Adding CT-proET-1 to the score resulted in an AUC of 0.92.

CONCLUSIONS

C-terminal-pro-endothelin-1 is superior to BNP for the prediction of a peak VO(2) < 14 mL kg(-1) min(-1) in patients referred for CPET. A score incorporating body mass index, diabetes status, spirometry, blood gases, BNP and CT-proET-1 improves the prediction of a peak VO(2) < 14 mL kg(-1) min(-1) based on single biomarkers.

B-type natriuretic peptides for the evaluation of exercise intolerance

BACKGROUND

Cardiopulmonary exercise testing is the method of choice for the differentiation of exercise intolerance. This study sought to assess the utility of B-type natriuretic peptide (BNP) and N-terminal-pro-B-type natriuretic peptide (NT-proBNP) for the identification of a cardiocirculatory exercise limitation.

METHODS

In 162 patients undergoing cardiopulmonary exercise testing, rest and peak exercise BNP and NT-proBNP levels were measured. In 94 patients fulfilling criteria for appropriate effort and sufficient diagnostic certainty, the accuracy of BNP and NT-proBNP for the prediction of a cardiocirculatory limitation, as assessed based on clinical and exercise testing data, was determined.

RESULTS

A cardiocirculatory limitation was identified in 27 (29%) patients. Median (interquartile range) resting BNP [162 (45-415) vs 39 (19-94) vs 24 (15-46) pg/mL; P <.001] and NT-proBNP [506 (129-1167) vs 77 (35-237) vs 34 (19-77) pg/mL; P <.001] were higher in patients with cardiocirculatory as compared with those with pulmonary limitation (n=28) and those without cardiocirculatory or pulmonary limitation (n=39). The area under the receiver operator characteristics curve for BNP and NT-proBNP to identify a cardiocirculatory limitation was 0.79 and 0.84, respectively (P=.15 for comparison of the curves). Sensitivity and specificity of the optimal BNP cutoff of 85 pg/mL were 63% and 84%, respectively. Sensitivity and specificity of the optimal NT-proBNP cutoff of 223 pg/mL were 74% and 85%, respectively. Peak exercise biomarkers were not more accurate than resting levels.

CONCLUSIONS

Among patients referred for cardiopulmonary exercise testing for evaluation of unexplained exercise intolerance, BNP and NT-proBNP were similarly useful to identify those with a cardiocirculatory limitation.