Role of cardiopulmonary exercise testing in clinical stratification in heart failure. A position paper from the Committee on Exercise Physiology and Training of the Heart Failure Association of the European Society of Cardiology

Exercise testing in patients with tricuspid regurgitation undergoing transcatheter tricuspid valve intervention

BACKGROUND

Transcatheter tricuspid valve intervention (TTVI) has shown promising results with persistent reduction of tricuspid regurgitation (TR) and improvements in functional class and quality of life (QOL).

OBJECTIVES

To analyze the impact of TTVI on maximal and submaximal exercise capacity (SEC).

METHODS

Constant work-rate exercise-time (CWRET) testing reflects SEC, which is more likely to be relevant for daily life activities and provides more differentiated physiological insight into the nature of exercise intolerance. Thus, 30 patients undergoing TTVI (21 direct annuloplasty and 9 edge-to-edge repair) received cardiopulmonary exercise testing (CPET) and CWRET (at 75% of maximum work rate in the initial CPET) before and 3 months after TTVI.

RESULTS

Patients' age was 80.5 [74.8-82.3] years and 53.3% were female. TR reduction ≥ 2 grades was achieved in 93.3% (TR grade ≤ moderate in 83.3%). Echocardiography revealed improved right ventricular (RV) characteristics with decreased RV basal diameter (47.0 mm [43.0-54.3] vs. 41.5 mm [36.8-48.0]; p < 0.001) and decreased inferior caval vein diameter. CWRET testing showed a significantly improved SEC (246.5 s [153.8-416.8] vs. 338.5 s [238.8-611.8] p = 0.001). Maximum oxygen uptake showed a positive trend without statistically significant differences (9.9 ml/min/kg [8.6-12.4] vs. 11.7 ml/min/kg [9.7-13.3]; p = 0.31). In contrast to the six-minute-walking distance (6MWD), SEC correlated moderately with effective regurgitation orifice area reduction (r = 0.385; p = 0.036), increased cardiac output (r = 0.378; p = 0.039), and improved QOL (r = 387; p = 0.035).

CONCLUSION

Improvements in exercise capacity after TTVI mainly occur in the submaximal rather than in the maximal exercise range and correlate with hemodynamic effects and QOL. This may have a methodological impact on assessment of exercise capacity in these patients.

International Society for Heart and Lung Transplantation Guidelines for the Evaluation and Care of Cardiac Transplant Candidates-2024

The "International Society for Heart and Lung Transplantation Guidelines for the Evaluation and Care of Cardiac Transplant Candidates-2024" updates and replaces the "Listing Criteria for Heart Transplantation: International Society for Heart and Lung Transplantation Guidelines for the Care of Cardiac Transplant Candidates-2006" and the "2016 International Society for Heart Lung Transplantation Listing Criteria for Heart Transplantation: A 10-year Update." The document aims to provide tools to help integrate the numerous variables involved in evaluating patients for transplantation, emphasizing updating the collaborative treatment while waiting for a transplant. There have been significant practice-changing developments in the care of heart transplant recipients since the publication of the International Society for Heart and Lung Transplantation (ISHLT) guidelines in 2006 and the 10-year update in 2016. The changes pertain to 3 aspects of heart transplantation: (1) patient selection criteria, (2) care of selected patient populations, and (3) durable mechanical support. To address these issues, 3 task forces were assembled. Each task force was cochaired by a pediatric heart transplant physician with the specific mandate to highlight issues unique to the pediatric heart transplant population and ensure their adequate representation. This guideline was harmonized with other ISHLT guidelines published through November 2023. The 2024 ISHLT guidelines for the evaluation and care of cardiac transplant candidates provide recommendations based on contemporary scientific evidence and patient management flow diagrams. The American College of Cardiology and American Heart Association modular knowledge chunk format has been implemented, allowing guideline information to be grouped into discrete packages (or modules) of information on a disease-specific topic or management issue. Aiming to improve the quality of care for heart transplant candidates, the recommendations present an evidence-based approach.

The role of exercise training and dietary sodium restriction in heart failure rehabilitation: A systematic review

Heart failure (HF) rehabilitation seeks to enhance the entire well-being and quality of life of those with HF by focusing on both physical and mental health. Non-pharmacological measures, particularly exercise training, and dietary salt reduction, are essential components of heart failure rehabilitation. This study examines the impact of these components on the recovery of patients with heart failure. By conducting a comprehensive analysis of research articles published from 2010 to 2024, we examined seven relevant studies collected from sources that include PubMed and Cochrane reviews. Our findings indicate that engaging in physical activity leads to favorable modifications in the heart, including improved heart contractility, vasodilation, and cardiac output. These alterations enhance the delivery of oxygen to the peripheral tissues and reduce symptoms of heart failure, such as fatigue and difficulty breathing. Nevertheless, decreasing the consumption of salt in one's diet to less than 1500 mg per day did not have a substantial impact on the frequency of hospitalizations, visits to the emergency room, or overall mortality when compared to conventional treatment. The combination of sodium restriction and exercise training can have synergistic effects due to their complementary modes of action. Exercise improves cardiovascular health and skeletal muscle metabolism, while sodium restriction increases fluid balance and activates neurohormonal pathways. Therefore, the simultaneous usage of both applications may result in more significant enhancements in HF symptoms and clinical outcomes compared to using each program alone.

Left ventricular global longitudinal strain and cardiorespiratory fitness in patients with heart failure: Systematic review and meta-analysis

BACKGROUND

There is no definition for strain deformation values in relation to cardiorespiratory fitness (CRF) in different heart failure (HF) phenotypes.

AIM

To identify the relationship between echocardiographic systolic function measurements and CRF in HF patients.

METHODS

Systematic review and meta-analysis following the PRISMA recommendations. Studies reporting echocardiographic assessments of left ventricular global longitudinal strain (LVGLS), left ventricular ejection fraction (LVEF), and direct measurement of peak oxygen uptake (VO2peak) in HF patients with reduced or preserved LVEF (HFrEF, HFpEF) were included. The patients were divided into Weber classes according to VO2peak.

RESULTS

A total of 25 studies involving of 2,136 patients (70.5% with HFpEF) were included. Mean LVEF and LVGLS were similar in HFpEF patients in Weber Class A/B and Class C/D. In HFrEF patients, a non-significant difference was found in LVEF between Weber Class A/B (30.2% [95%CI: 29.6 to 30.9%]) and Class C/D (25.2% [95%CI: 20.5 to 29.9%]). In HFrEF patients, mean LVGLS was significantly lower in Class C/D compared to Class A/B (6.5% [95%CI: 6.0 to 7.1%] and 10.3% [95%CI: 9.0 to 11.5%], respectively). The correlation between VO2peak and LVGLS (r2 = 0.245) was nearly twofold stronger than that between VO2peak and LVEF (r2 = 0.137).

CONCLUSIONS

Low LVGLS values were associated with low CRF in HFrEF patients. Although a weak correlation was found between systolic function at rest and CRF, the correlation between VO2peak and LVGLS was nearly twofold stronger than that with LVEF, indicating that LVGLS may be a better predictor of CRF in patients with HFrEF.

The Usefulness of Cardiopulmonary Exercise Testing to Detect Functional Improvement after Transcatheter Valve Procedures: What Do We Know So Far?

Transcatheter valve procedures have become a cornerstone in the management of patients with valvular heart disease and high surgical risk, especially for aortic stenosis and mitral and tricuspid regurgitation. Cardiopulmonary exercise testing (CPET) is generally considered the gold standard for objectively quantifying functional capacity, providing a comprehensive evaluation of the human body's performance, particularly in patients with heart failure (HF). Its accurate assessment is valuable for exploring the pathogenetic mechanisms implicated in HF-related functional impairment. It is also useful for objectively staging the clinical severity and the prognosis of the disease. The improvement in functional capacity after transcatheter valve procedures may be clinically relevant and may provide prognostic information, even in this setting. However, it remains to be fully determined as data on the topic are limited. This review aims to summarize the available evidence on the usefulness of CPET to assess functional improvement in patients undergoing transcatheter valve procedures.

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

OBJECTIVE

To 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).

DESIGN

Secondary analysis of data from the HIIT or MISS UK trial.

SETTING

Six 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).

PARTICIPANTS

382 participants with CAD (N=382) (mean age: 58.8±9.6y; mean body mass index: 29.0±4.3 kg/m2).

MAIN OUTCOME MEASURES

We 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.

RESULTS

Responders 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.

CONCLUSIONS

In 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.

Functional limitation predicts mortality in heart failure with preserved ejection fraction

BACKGROUND

While the prognostic value of six-minute walking test (6MWT) in patients with heart failure (HF) and reduced ejection fraction has been firmly established, there are few or no data correlating the distance walked during 6MWT (6MWD) with mortality in patients with HF with preserved ejection fraction (HFpEF) METHODS: We studied 482 patients with HFpEF who had been admitted to inpatients cardiac rehabilitation. The primary outcome was 3-year all-cause mortality. The association between 6MWD and the primary outcome was assessed using multivariable models. Established risk markers were incorporated into the models.

RESULTS

174 patients died during the 3-year follow-up. Taking the highest tertile of 6MWD (≥360 m) as reference, the adjusted hazard ratio (HR) of the primary outcome was 2.23 (95 % CI 1.31-3.78; p = .003) for the patients in the intermediate tertile (241-359 m) and 4.94 (95 % CI 2.90-8.39; p < .001) for those in the lowest tertile (≤240 m). The annual mortality rate was 25.0 % in the lowest tertile, 10.9 % in the intermediate tertile, and 5.3 % in the highest tertile. When the distance walked was normalized for age, sex, and body mass index and expressed as percent-of-predicted walking distance, the adjusted HR was 1.30 (95 % CI 0.76-2.22; p = .331) for the patients in the intermediate tertile (58.2 % to 77.6 %) and 3.52 (95 % CI 2.12-5.85; p < .001) for those in the lowest tertile (≤58.1 %).

CONCLUSIONS

Our findings suggest that measuring functional capacity by evaluating the distance that a patient can walk over a period of 6 min provides important prognostic information in HFpEF.

Changes in 6-min walk test is an independent predictor of death in chronic heart failure with reduced ejection fraction

AIMS

Functional capacity provides important clinical information in patients with heart failure (HF) and reduced ejection fraction (HFrEF). The 6-min walk test (6MWT) is a simple and inexpensive tool for assessing functional capacity and risk. Although change in 6MWT is frequently used as a surrogate outcome in HF trials, the association with mortality is unclear. We aimed to assess the prognostic importance of changes in 6MWT.

METHODS AND RESULTS

Patients with chronic HFrEF referred to HF outpatient clinics in Norway completed a 6MWT at the first visit (baseline) and at a stable follow-up visit after treatment optimization (follow-up). Absolute and relative changes in 6MWT were analysed in association with mortality risk using Cox regression models and flexible cubic splines. The study included 3636 HFrEF patients aged 67.3 ± 11.6 years, 23% women, with left ventricular ejection fraction 30 ± 7%. At baseline, mean 6MWT was 438 ± 125 m, median N-terminal pro-B-type natriuretic peptide (NT-proBNP) 1574 (732-3093) ng/L, and 27% had New York Heart Association (NYHA) class III/IV. After optimization of guideline-directed medical therapy (median 147 [86-240] days), 6MWT increased by mean 40 ± 74 m, NT-proBNP decreased by median 425 (14-1322) ng/L, and NYHA class improved in 38% of patients. Patients with greater improvements in 6MWT were younger, with greater improvements in NYHA class (r = 0.27, p < 0.001) and larger reductions in NT-proBNP concentrations (r = 0.19, p < 0.001). After mean 845 ± 595 days, 419 (11.5%) patients were dead. Both absolute and relative changes in 6MWT were non-linearly associated with survival, attenuating as 6MWT increased. A 50 m increase in 6MWT was associated with a 17% lower mortality risk (hazard ratio 0.84, 95% confidence interval 0.77-0.90, p < 0.001) in the fully adjusted model, including changes in NYHA class, NT-proBNP concentrations, and other established risk factors. The associations were more pronounced in patients with lower baseline 6MWT and higher age.

CONCLUSION

Improvement in 6MWT in patients with HFrEF is associated with increased survival, independent of changes in NT-proBNP and NYHA class. These findings support 6MWT change as a surrogate outcome in HF trials.

Evaluating current assessment techniques of cardiorespiratory fitness

INTRODUCTION

Considerable and convincing global data from cohorts across the health spectrum (i.e. apparently healthy to known disease) indicate that cardiorespiratory fitness (CRF) is a major predictor of overall and cardiovascular disease (CVD)-survival, seemingly with greater prognostic resolution compared to other traditional CVD risk factors. Therefore, the assessment of CRF in research and clinical settings is of major importance.

AREAS COVERED

In this manuscript, we review the technology of measuring CRF assessed by the 'gold standard,' cardiopulmonary exercise testing (CPET), as well as with various other methods (e.g. estimated metabolic equivalents, 6-minute walk tests, shuttle tests, and non-exercise equations that estimate CRF), all of which provide significant prognostic information for CVD- and all-cause survival. The literature through May 2024 has been cited.

EXPERT OPINION

The promotion of physical activity in efforts to improve levels of CRF is needed throughout the world to improve lifespan and, more importantly, healthspan. The routine assessment of CRF should be considered a vital sign that is routinely assessed in clinical practice.

Effects of sacubitril/valsartan on the functional capacity of real-world patients in Italy: the REAL.IT study on heart failure with reduced ejection fraction

Background

Heart failure (HF) significantly affects the morbidity, mortality, and quality of life of patients. New therapeutic strategies aim to improve the functional capacity and quality of life of patients while controlling HF-related risks. Real-world data on both the functional and cardiopulmonary exercise capacities of patients with HF with reduced ejection fraction upon sacubitril/valsartan use are lacking.

Methods

A multicenter, retrospective, cohort study, called REAL.IT, was performed based on the data collected from the electronic medical records of nine specialized HF centers in Italy. Cardiopulmonary exercise testing was performed at baseline and after 12 months of sacubitril/valsartan therapy, monitoring carbon dioxide production (VCO2) and oxygen consumption (VO2).

Results

The functional capacities of 170 patients were evaluated. The most common comorbidities were hypertension and diabetes (i.e., 53.5 and 32.4%, respectively). At follow-up, both the VO2 peak (from 15.1 ± 3.7 ml/kg/min at baseline to 17.6 ± 4.7 ml/kg/min at follow-up, p < 0.0001) and the predicted % VO2 peak (from 55.5 ± 14.1 to 65.5 ± 16.9, p < 0.0001) significantly increased from baseline. The VO2 at the anaerobic threshold (AT-VO2) increased from 11.5 ± 2.6 to 12.5 ± 3.3 ml/kg/min (p = 0.021), and the rate ratio between the oxygen uptake and the change in work (ΔVO2/Δwork slope) improved from 9.1 ± 1.5 to 9.9 ± 1.6 ml/min/W (p < 0.0001).

Conclusions

Sacubitril/valsartan improves the cardiopulmonary capacity of patients with HFrEF in daily clinical practice in Italy.

Phenotyping cardiopulmonary exercise testing measures in heart failure with reduced ejection fraction: A comparison between Italy and Brazil

BACKGROUND

While patients with heart failure (HF) with reduced left ventricular ejection fraction (HFrEF) constitutes a global health crisis the incidence, prevalence and prognosis of the disease may differ depending on the continent and country.

OBJECTIVE

To profile, analyze and compare cardiopulmonary exercise testing (CPET) data of patients with HFrEF between Italian and Brazilian cohorts.

METHODS

In this observational study, a total of 630 patients with clinical and functional diagnosis of HFrEF (315 patients from Brazil and 315 patients from Italy) performed CPET.

RESULTS

Although Brazilian patients were slightly younger (Brazil 60±10 vs Italy 64±11 p<0.001) with a better peak oxygen consumption (V̇O2), circulatory power and left ventricular ejection fraction (LVEF) (p<0.01), ventilatory inefficiency and oscillation ventilation was higher when compared to the Italian cohort. When stratifying patients with LVEF≤30 % and age≥60 years, Brazilian patients presented worse ventilatory efficiency, and lower peak V̇O2 compared to the Italian cohort.

CONCLUSION

Patients with HFrEF from Brazil exhibited higher ventilatory inefficiency and a greater prevalence of oscillatory ventilation during CPET compared to patients with the same diagnosis from Italy.

Back to the basics: The need for an etiological classification of chronic heart failure

The left ventricular (LV) ejection fraction (LVEF), despite its severe limitations, has had an epicentral role in heart failure (HF) classification, management, and risk stratification for decades. The major argument favoring the LVEF based HF classification has been that it defines groups of patients in which treatment is effective. However, this reasoning has recently collapsed, since medical treatment with neurohormonal inhibitors, has proved beneficial in most HF patients regardless of the LVEF. In addition, there has been compelling evidence, that the LVEF provides poor guidance for device treatment of chronic HF (implantation of cardioverter defibrillator, cardiac resynchronization therapy) since sudden cardiac death may occur and cardiac dyssynchronization may be disastrous in all HF patients. The same holds true for LV assist device implantation, in which the LVEF has been used as a surrogate for LV size. In this review article we update the evidence questioning the use of LVEF-based HF classification and argue that guidance of chronic HF treatment should transition to more contemporary concepts. Specifically, we propose an etiologic chronic HF classification predominantly based on epidemiological data, which will be foundational for further higher resolution phenotyping in the emerging era of precision medicine.

Profile of serum microRNAs in heart failure with reduced and preserved ejection fraction: Correlation with myocardial remodeling

Background and aims

Cardiomyocyte hypertrophy and interstitial fibrosis are key components of myocardial remodeling in Heart Failure (HF) with preserved (HFpEF) or reduced ejection fraction (HFrEF). MicroRNAs (miRNAs) are non-coding, evolutionarily conserved RNA molecules that may offer novel insights into myocardial remodeling. This study aimed to characterize miRNA expression in HFpEF (LVEF ≥  45%) and HFrEF (LVEF < 45%) and its association with myocardial remodeling.

Methods

Prospectively enrolled symptomatic HF patients (HFpEF:n = 36; HFrEF:n = 31) and controls (n = 23) underwent cardiac magnetic resonance imaging with T1-mapping and circulating miRNA expression (OpenArray system).

Results

13 of 188 miRNAs were differentially expressed between HF groups (11 downregulated in HFpEF). Myocardial extracellular volume (ECV) was increased in both HF groups (HFpEF 30 ± 5%; HFrEF 30 ± 3%; controls 26 ± 2%, p < 0.001). miR-128a-3p, linked to cardiac hypertrophy, fibrosis, and dysfunction, correlated positively with ECV in HFpEF (r = 0.60, p = 0.01) and negatively in HFrEF (r = - 0.51, p = 0.04). miR-423-5p overexpression, previously associated HF mortality, was inversely associated with LVEF (r = - 0.29, p = 0.04) and intracellular water lifetime (τ ic) (r = - 0.45, p < 0.05) in both HF groups, and with NT-proBNP in HFpEF (r = - 0.63, p < 0.01).

Conclusions

miRNA expression profiles differed between HF phenotypes. The differential expression and association of miR-128a-3p with ECV may reflect the distinct vascular, interstitial, and cellular etiologies of HF phenotypes.

Hemodynamic parameters at rest predicting exercise capacity in patients supported with left ventricular assist device

Left ventricular assist devices improve prognosis and quality of life, but exercise capacity remains limited in most patients after device implantation. Left ventricular assist device optimization through right heart catheterization reduces device-related complications. However, hemodynamic parameters associated with exercise capacity under optimized conditions. The aim of this study was to elucidate the predictors of exercise capacity from hemodynamic parameters at rest after left ventricular assist device optimization. We retrospectively reviewed 24 patients who underwent a ramp test with right heart catheterization, echocardiography and cardiopulmonary exercise testing more than 6 months after left ventricular assist device implantation. Pump speed was optimized to a lower setting that achieved right atrial pressure < 12 mmHg, pulmonary capillary wedge pressure < 18 mmHg, and cardiac index > 2.2 L/min/m2, then exercise capacity was assessed by cardiopulmonary exercise testing. After left ventricular assist device optimization, the mean right atrial pressure, pulmonary capillary wedge pressure, cardiac index, and peak oxygen consumption were 7 ± 5 mmHg, 10 ± 7 mmHg, 2.7 ± 0.5 L/min/m2, and 13.2 ± 3.0 mL/min/kg, respectively. Pulse pressure, stroke volume, right atrial pressure, mean pulmonary artery pressure, and pulmonary capillary wedge pressure were significantly associated with peak oxygen consumption. Multivariate linear regression analysis of factors predicting peak oxygen consumption revealed that pulse pressure, right atrial pressure, and aortic insufficiency remained independent predictors (β = 0.401, p = 0.007; β = - 0.558, p < 0.001; β = - 0.369, p = 0.010, respectively). Our findings suggests that cardiac reserve, volume status, right ventricular function, and aortic insufficiency predict exercise capacity in patients with a left ventricular assist device.

Novel Strategies in Diagnosing Heart Failure with Preserved Ejection Fraction: A Comprehensive Literature Review

Heart failure (HF) with preserved ejection fraction (HFpEF) is a prevalent global condition affecting approximately 50% of the HF population. With the aging of the worldwide population, its incidence and prevalence are expected to rise even further. Unfortunately, until recently, no effective medications were available to reduce the high mortality and hospitalization rates associated with HFpEF, making it a significant unmet need in cardiovascular medicine. Although HFpEF is commonly defined as HF with normal ejection fraction and elevated left ventricular filling pressure, performing invasive hemodynamic assessments on every individual suspected of having HFpEF is neither feasible nor practical. Consequently, several clinical criteria and diagnostic tools have been proposed to aid in diagnosing HFpEF. Overall, these criteria and tools are designed to assist healthcare professionals in identifying and evaluating patients who may have HFpEF based on a combination of signs, symptoms, biomarkers, and non-invasive imaging findings. By employing these non-invasive diagnostic approaches, clinicians can make informed decisions regarding the best pharmacological and rehabilitation strategies for individuals with suspected HFpEF. This literature review aims to provide an overview of all currently available methods for diagnosing and monitoring this disabling condition.

Incremental prognostic value of functional impairment assessed by 6-min walking test for the prediction of mortality in heart failure

Natriuretic peptides (NP) are recognized as the most powerful predictors of adverse outcomes in heart failure (HF). We hypothesized that a measure of functional limitation, as assessed by 6-min walking test (6MWT), would improve the accuracy of a prognostic model incorporating a NP. This was a multicenter observational retrospective study. We studied the prognostic value of severe functional impairment (SFI), defined as the inability to perform a 6MWT or a distance walked during a 6MWT < 300 m, in 1696 patients with HF admitted to cardiac rehabilitation. The primary outcome was 1-year all-cause mortality. After adjusting for the baseline multivariable risk model-including age, sex, systolic blood pressure, anemia, renal dysfunction, sodium level, and NT-proBNP-or for the MAGGIC score, SFI had an odds ratio of 2.58 (95% CI 1.72-3.88; p < 0.001) and 3.12 (95% CI 2.16-4.52; p < 0.001), respectively. Adding SFI to the baseline risk model or the MAGGIC score yielded a significant improvement in discrimination and risk classification. Our data suggest that a simple, 6MWT-derived measure of SFI is a strong predictor of death and provide incremental prognostic information over well-established risk markers in HF, including NP, and the MAGGIC score.

Prognostic Value of Hemodynamic Gain Index in Patients With Heart Failure With Reduced Ejection Fraction

BACKGROUND

Assessment of functional capacity in patients with heart failure with reduced ejection fraction (HFrEF) is essential for risk stratification, and it traditionally relied on cardiopulmonary exercise testing (CPET)-derived peak oxygen consumption (peak Vo2).

OBJECTIVES

This study sought to investigate the prognostic value of alternative nonmetabolic exercise testing parameters in a contemporary cohort with HFrEF.

METHODS

Medical records of 1,067 consecutive patients with chronic HFrEF who underwent CPET from December 2012 to September 2020 were reviewed for a primary outcome that was a composite of all-cause mortality, left ventricular assist device implantation, and/or heart transplantation. Multivariable Cox regression and log-rank testing were used to determine prognostic values of various exercise testing variables.

RESULTS

The primary outcome was identified in 331 of 954 patients (34.7%) of the HFrEF cohort (median follow-up time, 946 days). After adjustment for demographics, cardiac parameters, and comorbidities, higher hemodynamic gain index (HGI) and peak rate-pressure product (RPP) were associated with greater event-free survival (adjusted HR per doubling: 0.76 and 0.36; 95% CI: 0.67-0.87 and 0.28-0.47; all P < 0.001, respectively). Moreover, HGI (area under the curve [AUC]: 0.69; 95% CI: 0.65-0.72) and peak RPP (AUC: 0.71; 95% CI: 0.68-0.74) were comparable to the standard peak Vo2 (AUC: 0.70; 95% CI: 0.66-0.73; P for comparison = 0.607 and 0.393, respectively) for primary outcome discrimination.

CONCLUSIONS

HGI and peak RPP show good correlation with peak Vo2 in terms of prognostication and outcome discrimination in patients with HFrEF and may serve as suitable alternatives to CPET-derived prognostic variables.

Heart Failure: Recent Advances and Breakthroughs

Heart failure (HF) is a common clinical condition encountered in various healthcare settings with a vast socioeconomic impact. Recent advancements in pharmacotherapy have led to the evolution of novel therapeutic agents with a decrease in hospitalization and mortality rates in HF with reduced left ventricular ejection fraction (HFrEF). Lately, the introduction of artificial intelligence (AI) to construct decision-making models for the early detection of HF has played a vital role in optimizing cardiovascular disease outcomes. In this review, we examine the newer therapies and evidence behind goal-directed medical therapy (GDMT) for managing HF. We also explore the application of AI and machine learning (ML) in HF, including early diagnosis and risk stratification for HFrEF.

Deep learned representations of the resting 12-lead electrocardiogram to predict at peak exercise

AIMS

To leverage deep learning on the resting 12-lead electrocardiogram (ECG) to estimate peak oxygen consumption (V˙O2peak) without cardiopulmonary exercise testing (CPET).

METHODS AND RESULTS

V ˙ O 2 peak estimation models were developed in 1891 individuals undergoing CPET at Massachusetts General Hospital (age 45 ± 19 years, 38% female) and validated in a separate test set (MGH Test, n = 448) and external sample (BWH Test, n = 1076). Three penalized linear models were compared: (i) age, sex, and body mass index ('Basic'), (ii) Basic plus standard ECG measurements ('Basic + ECG Parameters'), and (iii) basic plus 320 deep learning-derived ECG variables instead of ECG measurements ('Deep ECG-V˙O2'). Associations between estimated V˙O2peak and incident disease were assessed using proportional hazards models within 84 718 primary care patients without CPET. Inference ECGs preceded CPET by 7 days (median, interquartile range 27-0 days). Among models, Deep ECG-V˙O2 was most accurate in MGH Test [r = 0.845, 95% confidence interval (CI) 0.817-0.870; mean absolute error (MAE) 5.84, 95% CI 5.39-6.29] and BWH Test (r = 0.552, 95% CI 0.509-0.592, MAE 6.49, 95% CI 6.21-6.67). Deep ECG-V˙O2 also outperformed the Wasserman, Jones, and FRIEND reference equations (P < 0.01 for comparisons of correlation). Performance was higher in BWH Test when individuals with heart failure (HF) were excluded (r = 0.628, 95% CI 0.567-0.682; MAE 5.97, 95% CI 5.57-6.37). Deep ECG-V˙O2 estimated V˙O2peak <14 mL/kg/min was associated with increased risks of incident atrial fibrillation [hazard ratio 1.36 (95% CI 1.21-1.54)], myocardial infarction [1.21 (1.02-1.45)], HF [1.67 (1.49-1.88)], and death [1.84 (1.68-2.03)].

CONCLUSION

Deep learning-enabled analysis of the resting 12-lead ECG can estimate exercise capacity (V˙O2peak) at scale to enable efficient cardiovascular risk stratification.

Effects of prehabilitation resistance training in mild to moderate clinically frail patients awaiting coronary artery bypass graft surgery

Coronary artery disease is one of the main causes of mortality and morbidity among chronic heart diseases worldwide. Patients reported chronic chest pain as the primary symptom of coronary artery disease. Due to its progressive nature, it affects the health status and functional capacity of the patients. The current study was planned to compare the effects of prehabilitation resistance training in mild to moderate clinically frail patients awaiting coronary artery bypass graft (CABG). A randomized controlled trial was conducted on 74 patients awaiting CABG at the Faisalabad Institute of Cardiology, Faisalabad, Pakistan. A Modified Healthy Heart Questionnaire was used for screening of the patients. Interventions applied were resistance training by using cuff weights/dumbbells at light intensity (40%-50%) of a maximum of one repetition (10-15 repetitions for one to three times a day) per major muscle groups of upper and lower limbs of the body on weekly basis. The main outcome measures were the 6-minute walk test (6MWT), the New York Heart Association (NYHA) for heart failure, the clinical frailty score, and the essential frailty toolset. Significant differences between group A (resistance training group) and group B (conventional physical therapy group) patients were observed. The mean ranks for 6MWT in group A and group B were 1.70 and 1.55, respectively. The mean ranks of NYHA in group A and group B were 1.68 and 2.84, respectively. Clinical frailty scores in group A and group B were 2.68 and 2.74, respectively, with the essential frailty toolset in group A and group B were 1.14 and 1.11, respectively. There were significant (p < 0.05) differences within and between groups for prehabilitation resistance training after CABG. The study showed that the resistance training group had improved the clinical frailty score, strength, endurance, and functional capacity in patients who underwent elective CABG.

Low-dose exercise protects the heart against established myocardial infarction via IGF-1-upregulated CTRP9 in male mice

Regular exercise is recommended as an important component of therapy for cardiovascular diseases in clinical practice. However, there are still major challenges in prescribing an optimized exercise regimen to individual patients with established cardiac disease. Here, we tested the effects of different exercise doses on cardiac function in mice with established myocardial infarction (MI). Exercise was introduced to mice with MI after 4 weeks of surgery. Low-dose exercise (15 min/day for 8 weeks) improved mortality and cardiac function by increasing 44.39% of ejection fractions while inhibiting fibrosis by decreasing 37.74% of distant region. Unlike higher doses of exercise, low-dose exercise consecutively upregulated cardiac expression of C1q complement/tumor necrosis factor-associated protein 9 (CTRP9) during exercise (>1.5-fold). Cardiac-specific knockdown of CTRP9 abolished the protective effects of low-dose exercise against established MI, while cardiac-specific overexpression of CTRP9 protected the heart against established MI. Mechanistically, low-dose exercise upregulated the transcription factor nuclear receptor subfamily 2 group F member 2 by increasing circulating insulin-like growth factor 1 (IGF-1), therefore, upregulating cardiac CTRP9 expression. These results suggest that low-dose exercise protects the heart against established MI via IGF-1-upregulated CTRP9 and may contribute to the development of optimized exercise prescriptions for patients with MI.

Prognostic value of cardiopulmonary exercise testing repetition during follow-up of clinically stable patients with severe dilated cardiomyopathy. A preliminary study

BACKGROUND

Cardiopulmonary exercise testing (CPET) is a recognized tool for prognostic stratification in patients with dilated cardiomyopathy (DCM). Given the lack of data currently available, the aim of this study was to test the prognostic value of repeating CPET during the follow-up of patients with DCM.

METHODS

This multicenter, retrospective study, analyzed DCM patients who consecutively performed two echocardiographies and CPETs during clinical stability. The study end-point was a composite of death from all causes, heart transplantation, left ventricular assist device implantation, life-threatening ventricular arrhythmias or hospitalization for heart failure.

RESULTS

216 DCM patients were enrolled (52 years, 78% male, NYHA I-II 82%, LVEF 32%, 94% on ACE inhibitors/ARNI, 95% on beta-blockers). The interval between CPETs was 15 months. During a median follow-up of 38 months from the second CPET, 102 (47%) patients experienced the study end-point. Among them, there was stability of echocardiographic values but a significant worsening of functional capacity. Among the 173 patients (80%) who did not show echocardiographic left ventricular reverse remodeling (LVRR), the 1-year prevalence of the study-end point was higher in patients who worsened vs patients who maintained stable their functional capacity at CPET (38 vs. 15% respectively, p-value: 0.001). These results were consistent also when excluding life-threatening ventricular arrhythmias from the composite end-point.

CONCLUSION

In clinically stable DCM patients with important depression of LVEF, the repetition of combined echocardiography and CPET might be recommended. When LVRR fails, 1-year repetition of CPET could identify higher-risk patients.

End-tidal oxygen partial pressure is a strong prognostic predictive factor in patients with cardiac disease

BACKGROUND

Cardiopulmonary exercise testing (CPET) variables represent central and peripheral factors and combined factors in the pathology of patients with cardiac disease. The difference in end-tidal oxygen partial pressure from resting to anaerobic threshold (ΔPETO2 ) may represent predominantly peripheral factors. This study aimed to verify the prognostic significance of ΔPETO2 for major adverse cardiac and cerebrovascular events (MACCE) in cardiac patients, including comparison with the minute ventilation-carbon dioxide production relationship (VE/VCO2 slope), and peak oxygen uptake (VO2 ).

METHODS

In total, 185 patients with cardiac disease who underwent CPET were consecutively enroled in this retrospective study. The primary endpoint was 3-year MACCE. The ability of ΔPETO2 , VE/VCO2 slope, and peak VO2 to predict MACCE was examined.

RESULTS

Optimal cut-off values for predicting MACCE were 2.0 mmHg for ΔPETO2 (area under the curve [AUC]: 0.829), 29.8 for VE/VCO2 slope (AUC: 0.734), and 19.0 mL/min/kg for peak VO2 (AUC: 0.755). The AUC of ΔPETO2 was higher than those of VE/VCO2 slope and peak VO2 . The MACCE-free survival rate was significantly lower in the ΔPETO2  ≤ 2.0 group versus the ΔPETO2  > 2.0 group (44.4% vs. 91.2%, p < 0.001). ΔPETO2  ≤ 2.0 was an independent predictor of MACCE after adjustment for age and VE/VCO2 slope (hazard ratio [HR], 7.28; p < 0.001) and after adjustment for age and peak VO2 (HR, 6.52; p < 0.001).

CONCLUSION

ΔPETO2 was a strong predictor of MACCE independent of and superior to VE/VCO2 slope and peak VO2 in patients with cardiac disease.

Beyond VO2: the complex cardiopulmonary exercise test

Cardiopulmonary exercise test (CPET) is a valuable diagnostic tool with a specific application in heart failure (HF) thanks to the strong prognostic value of its parameters. The most important value provided by CPET is the peak oxygen uptake (peak VO2), the maximum rate of oxygen consumption attainable during physical exertion. According to the Fick principle, VO2 equals cardiac output (Qc) times the arteriovenous content difference [C(a-v)O2], where Ca is the arterial oxygen and Cv is the mixed venous oxygen content, respectively; therefore, VO2 can be reduced both by impaired O2 delivery (reduced Qc) or extraction (reduced arteriovenous O2 content). However, standard CPET is not capable of discriminating between these different impairments, leading to the need for 'complex' CPET technologies. Among non-invasive methods for Qc measurement during CPET, inert gas rebreathing and thoracic impedance cardiography are the most used techniques, both validated in healthy subjects and patients with HF, at rest and during exercise. On the other hand, the non-invasive assessment of peripheral muscle perfusion is possible with the application of near-infrared spectroscopy, capable of measuring tissue oxygenation. Measuring Qc allows, by having haemoglobin values available, to discriminate how much any VO2 deficit depends on the muscle, anaemia or heart.

Cardiopulmonary Exercise Testing in Patients with Heart Failure: Impact of Gender in Predictive Value for Heart Transplantation Listing

BACKGROUND

Exercise testing is key in the risk stratification of patients with heart failure (HF). There are scarce data on its prognostic power in women. Our aim was to assess the predictive value of the heart transplantation (HTx) thresholds in HF in women and in men.

METHODS

Prospective evaluation of HF patients who underwent cardiopulmonary exercise testing (CPET) from 2009 to 2018 for the composite endpoint of cardiovascular mortality and urgent HTx.

RESULTS

A total of 458 patients underwent CPET, with a composite endpoint frequency of 10.5% in females vs. 16.0% in males in 36-month follow-up. Peak VO2 (pVO2), VE/VCO2 slope and percent of predicted pVO2 were independent discriminators of the composite endpoint, particularly in women. The International Society for Heart Lung Transplantation recommended values of pVO2 ≤ 12 mL/kg/min or ≤14 if the patient is intolerant to β-blockers, VE/VCO2 slope > 35, and percent of predicted pVO2 ≤ 50% showed a higher diagnostic effectiveness in women. Specific pVO2, VE/VCO2 slope and percent of predicted pVO2 cut-offs in each sex group presented a higher prognostic power than the recommended thresholds.

CONCLUSION

Individualized sex-specific thresholds may improve patient selection for HTx. More evidence is needed to address sex differences in HF risk stratification.

Age Differences in Cardiopulmonary Exercise Testing Parameters in Heart Failure with Reduced Ejection Fraction

Background and Objectives: Cardiopulmonary exercise testing (CPET) is a cornerstone of risk stratification in heart failure with reduced ejection fraction (HFrEF). However, there is a paucity of evidence on its predictive power in older patients. The aim of this study was to evaluate the prognostic power of current heart transplantation (HTx) listing criteria in HFrEF stratified according to age groups. Materials and Methods: Consecutive patients with HFrEF undergoing CPET between 2009 and 2018 were followed-up for cardiac death and urgent HTx. Results: CPET was performed in 458 patients with HFrEF. The composite endpoint occurred in 16.8% of patients ≤50 years vs. 14.1% of patients ≥50 years in a 36-month follow-up. Peak VO2 (pVO2), VE/VCO2 slope and percentage of predicted pVO2 were strong independent predictors of outcomes. The International Society for Heart and Lung Transplantation thresholds of pVO2 ≤ 12 mL/kg/min (≤14 if intolerant to β-blockers), VE/VCO2 slope > 35 and percentage of predicted pVO2 ≤ 50% presented a higher overall diagnostic effectiveness in younger patients (≤50 years). Specific thresholds for each age subgroup outperformed the traditional cut-offs. Conclusions: Personalized age-specific thresholds may contribute to an accurate risk stratification in HFrEF. Further studies are needed to address the gap in evidence between younger and older patients.

Breath analysis combined with cardiopulmonary exercise testing and echocardiography for monitoring heart failure patients: the AEOLUS protocol

This paper describes the AEOLUS pilot study which combines breath analysis with cardiopulmonary exercise testing (CPET) and an echocardiographic examination for monitoring heart failure (HF) patients. Ten consecutive patients with a prior clinical diagnosis of HF with reduced left ventricular ejection fraction were prospectively enrolled together with 15 control patients with cardiovascular risk factors, including hypertension, type II diabetes or chronic ischemic heart disease. Breath samples were collected at rest and during CPET coupled with exercise stress echocardiography (CPET-ESE) protocol by means of needle trap micro-extraction and were analyzed through gas-chromatography coupled with mass spectrometry. The protocol also involved using of a selected ion flow tube mass spectrometer for a breath-by-breath isoprene and acetone analysis during exercise. At rest, HF patients showed increased breath levels of acetone and pentane, which are related to altered oxidation of fatty acids and oxidative stress, respectively. A significant positive correlation was observed between acetone and the gold standard biomarker NT-proBNP in plasma (r= 0.646,p< 0.001), both measured at rest. During exercise, some exhaled volatiles (e.g., isoprene) mirrored ventilatory and/or hemodynamic adaptation, whereas others (e.g., sulfide compounds and 3-hydroxy-2-butanone) depended on their origin. At peak effort, acetone levels in HF patients differed significantly from those of the control group, suggesting an altered myocardial and systemic metabolic adaptation to exercise for HF patients. These preliminary data suggest that concomitant acquisition of CPET-ESE and breath analysis is feasible and might provide additional clinical information on the metabolic maladaptation of HF patients to exercise. Such information may refine the identification of patients at higher risk of disease worsening.

Cardiopulmonary Exercise Testing in the Age of New Heart Failure Therapies: Still a Powerful Tool?

BACKGROUND

New therapies with prognostic benefits have been recently introduced in heart failure with reduced ejection fraction (HFrEF) management. The aim of this study was to evaluate the prognostic power of current listing criteria for heart transplantation (HT) in an HFrEF cohort submitted to cardiopulmonary exercise testing (CPET) between 2009 and 2014 (group A) and between 2015 and 2018 (group B).

METHODS

Consecutive patients with HFrEF who underwent CPET were followed-up for cardiac death and urgent HT.

RESULTS

CPET was performed in 487 patients. The composite endpoint occurred in 19.4% of group A vs. 7.4% of group B in a 36-month follow-up. Peak VO2 (pVO2) and VE/VCO2 slope were the strongest independent predictors of mortality. International Society for Heart and Lung Transplantation (ISHLT) thresholds of pVO2 ≤ 12 mL/kg/min (≤14 if intolerant to β-blockers) and VE/VCO2 slope > 35 presented a similar and lower Youden index, respectively, in group B compared to group A, and a lower positive predictive value. pVO2 ≤ 10 mL/kg/min and VE/VCO2 slope > 40 outperformed the traditional cut-offs. An ischemic etiology subanalysis showed similar results.

CONCLUSION

ISHLT thresholds showed a lower overall prognostic effectiveness in a contemporary HFrEF population. Novel parameters may be needed to improve risk stratification.

Exercise Oscillatory Ventilation Improves Heart Failure Prognostic Scores

BACKGROUND

Several heart failure (HF) prognostic risk scores are available to guide the ideal time for listing candidates for a heart transplant (HTx). The detection of exercise oscillatory ventilation (EOV) during cardiopulmonary exercise testing (CPET) is associated with advanced HF and a worse prognosis, and yet it is not accounted for in these risk scores. Therefore, this study aimed to assess whether EOV further adds prognostic value to HF scores.

METHODS

A single-centre retrospective cohort study was undertaken of consecutive HF patients with reduced ejection fraction (HFrEF) who underwent CPET from 1996 to 2018. The Heart Failure Survival Score (HFSS), Seattle Heart Failure Model (SHFM), Meta-analysis Global Group In Chronic Heart Failure (MAGGIC), and Metabolic Exercise Cardiac Kidney Index (MECKI) were calculated. The added value of EOV on top of those scores was assessed using a Cox proportional hazard model. The added discriminative power was also assessed by receiver operating characteristic curve comparison.

RESULTS

A total of 390 HF patients with a median age of 58 (IQR 50-65) years were investigated, of whom 78% were male and 54% had ischaemic heart disease. The median peak oxygen consumption was 15.7 mL/kg/min (IQR 12.8-20.1). Exercise oscillatory ventilation was detected in 153 (39.2%) patients. Over a median follow-up of 2 years, 61 patients died (49 due to a cardiovascular reason) and 54 had a HTx. Exercise oscillatory ventilation independently predicted the composite outcome of all-cause death and HTx. Furthermore, the presence of this ventilatory pattern significantly improved the prognostic performance of both HFSS and MAGGIC scores.

CONCLUSION

Exercise oscillatory ventilation was often found in a cohort of HF patients with reduced LVEF who underwent CPET. It was found that EOV added further prognostic value to contemporary HF scores, suggesting that this easily obtained parameter should be included in future modified HF scores.

Longer-Term Effects of Cardiac Telerehabilitation on Patients With Coronary Artery Disease: Systematic Review and Meta-Analysis

BACKGROUND

Cardiac telerehabilitation offers a flexible and accessible model for patients with coronary artery disease (CAD), effectively transforming the traditional cardiac rehabilitation (CR) approach.

OBJECTIVE

This systematic review and meta-analysis aimed to evaluate the long-term effectiveness of cardiac telerehabilitation.

METHODS

We searched randomized controlled trials (RCTs) in 7 electronic databases: PubMed, Web of Science, EMBASE, the Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, the China National Knowledge Infrastructure, and WANFANG. The primary outcome focused on cardiopulmonary fitness. For secondary outcomes, we examined cardiovascular risk factors (blood pressure, BMI, and serum lipids), psychological scales of depression and anxiety, quality of life (QoL), cardiac telerehabilitation adherence, and adverse events.

RESULTS

In total, 10 RCTs fulfilled the predefined criteria, which were reviewed in our meta-analysis. The results showed that after cardiac telerehabilitation, there was a significant difference in the improvement in long-term peak oxygen uptake compared to center-based CR (mean difference [MD] 1.61, 95% CI 0.38-2.85, P=.01), particularly after 6-month rehabilitation training (MD 1.87, 95% CI 0.34-3.39, P=.02). The pooled effect size of the meta-analysis indicated that there were no significant differences in the reduction in cardiovascular risk factor control. There was also no practical demonstration of anxiety scores or depression scores. However, cardiac telerehabilitation demonstrated an improvement in the long-term QoL of patients (MD 0.92, 95% CI 0.06-1.78, P=.04). In addition, the study reported a high completion rate (80%) for cardiac telerehabilitation interventions. The incidence of adverse events was also low during long-term follow-up.

CONCLUSIONS

Cardiac telerehabilitation proves to be more effective in improving cardiopulmonary fitness and QoL during the long-term follow-up for patients with CAD. Our study highlights monitoring-enabled and patient-centered telerehabilitation programs, which play a vital role in the recovery and development of CAD and in the long-term prognosis of patients.

Prognostic Value of 6-Minute Walk Test in Advanced Heart Failure With Reduced Ejection Fraction

There is limited evidence regarding the prognostic value of the 6-minute walk test for patients with advanced heart failure (HF). Accordingly, we studied 260 patients presenting to inpatient cardiac rehabilitation (CR) with advanced HF. The primary outcome was 3-year all-cause mortality after discharge from CR. The association between 6-minute walk distance (6MWD) and the primary outcome was determined using the multivariable Cox regression analysis. To avoid collinearity, 6MWD at admission (6MWDadm) to CR and 6MWD at discharge (6MWDdisch) from CR were analyzed separately. At multivariable analysis, 4 baseline characteristics (age, ejection fraction, systolic blood pressure, and blood urea nitrogen) were identified as prognostic of the primary outcome (baseline risk model). After adjusting for the baseline risk model, the hazard ratios of 6MWDadm and 6MWDdisch modeled as per 50-m increase for the primary outcome were 0.92 (95% confidence interval [CI] 0.85 to 0.99, p = 0.035) and 0.93 (95% CI 0.88 to 0.99, p = -017), respectively. After adjusting for the Meta-analysis Global Group in Chronic Heart Failure (MAGGIC) score, the corresponding hazard ratios were 0.91 (95% CI 0.84 to 0.98, p = 0.017) and 0.93 (95% CI 0.88 to 0.99, p = 0.016). The addition of either 6MWDadm or 6MWDdisch to the baseline risk model or the MAGGIC score yielded a statistically significant increase in global chi-square and in the net proportion of survivors reclassified downward. In conclusion, our data suggest that the distance covered during a 6-minute walk test predicts survival and provides incremental prognostic information on the top of well-established prognostic factors and the MAGGIC risk score in advanced HF.

Prognostic Role of Metabolic Exercise Testing in Heart Failure

Heart failure is a clinical syndrome with significant heterogeneity in presentation and severity. Serial risk-stratification and prognostication can guide management decisions, particularly in advanced heart failure, when progression toward advanced therapies or end-of-life care is warranted. Each currently utilized prognostic marker carries its own set of challenges in acquisition, reproducibility, accuracy, and significance. Left ventricular ejection fraction is foundational for heart failure syndrome classification after clinical diagnosis and remains the primary parameter for inclusion in most clinical trials; however, it does not consistently correlate with symptoms and functional capacity, which are also independently prognostic in this patient population. Utilizing the left ventricular ejection fraction as the sole basis of prognostication provides an incomplete characterization of this condition and is prone to misguide medical decision-making when used in isolation. In this review article, we survey and exposit the important role of metabolic exercise testing across the heart failure spectrum, as a complementary diagnostic and prognostic modality. Metabolic exercise testing, also known as cardiopulmonary exercise testing, provides a comprehensive evaluation of the multisystem (i.e., neurological, respiratory, circulatory, and musculoskeletal) response to exercise performance. These differential responses can help identify the predominant contributors to exercise intolerance and exercise symptoms. Additionally, the aerobic exercise capacity (i.e., oxygen consumption during exercise) is directly correlated with overall life expectancy and prognosis in many disease states. Specifically in heart failure patients, metabolic exercise testing provides an accurate, objective, and reproducible assessment of the overall circulatory sufficiency and circulatory reserve during physical stress, being able to isolate the concurrent chronotropic and stroke volume responses for a reliable depiction of the circulatory flow rate in real time.

Effects of cardiac rehabilitation on cardiopulmonary test parameters in heart failure: A real world experience

Background

Cardio-Pulmonary Exercise Test (CPET) is the gold standard for evaluation of patients with heart failure (HF); however, its use is limited in everyday practice. We analyzed the use of CPET for HF management in the real world.

Methods

From 2009 to 2022, 341 patients with HF underwent 12-16 weeks of rehabilitation in our Centre. We present data from 203 patients (60%), excluding those unable to perform CPET, those with anaemia and severe pulmonary disease. Before and after rehabilitation, we performed CPET, blood tests and echocardiography, tailoring individual physical training to the results of baseline test. The following variables were considered: peak Respiratory Equivalent Ratio (RER), peakVO₂ (ml/Kg/min), VO₂ at aerobic threshold (VO₂AT,% maximal), VE/VCO₂ slope, P_(ET)CO₂, VO₂ /Work ratio (ΔVO₂/ΔWork).

Results

Rehabilitation improved peak VO₂, pulse O₂, VO₂ AT and ΔVO₂/ΔWork in all patients by about 13% (p < 0.01). Most patients (126, 62%) showed a reduced left ventricular ejection fraction (HFrEF), but rehabilitation was effective also in patients with mildly reduced (HFmrEF: n = 55, 27%) or preserved ejection fraction (HFpEF: n = 22, 11%).

Conclusions

Rehabilitation in patients with heart failure induces a significant recovery of cardiorespiratory performance easily assessed by CPET, that is applicable to the majority of them and should be used routinely in the programming and evaluating of cardiac rehabilitation programs.

Effects of Sacubitril/Valsartan on Exercise Capacity in Patients with Heart Failure with Reduced Ejection Fraction and the Role of Percentage of Delayed Enhancement Measured by Cardiac Magnetic Resonance in Predicting Therapeutic Response: A Multicentre Study

Background: This study aims to evaluate the cardiopulmonary effects of sacubitril/valsartan therapy in patients with heart failure with reduced ejection fraction (HFrEF), investigating a possible correlation with the degree of myocardial fibrosis, as assessed by cardiac magnetic resonance. Methods: A total of 134 outpatients with HFrEF were enrolled. Results: After a mean follow-up of 13.3 ± 6.6 months, an improvement in ejection fraction and a reduction in E/A ratio, inferior vena cava size and N-terminal pro-B-type natriuretic peptide levels were observed. At follow-up, we observed an increase in VO₂ peak of 16% (p<0.0001) and in O₂ pulse of 13% (p=0.0002) as well as an improvement in ventilatory response associated with a 7% reduction in the VE/VCO₂ slope (p=0.0001). An 8% increase in the ΔVO₂/Δ work ratio and an 18% increase in exercise tolerance were also observed. Multivariate logistic regression analysis showed that the main predictors of events during follow-up were VE/VCO₂ slope >34 (OR 3.98; 95% CI [1.59-10.54]; p=0.0028); ventilatory oscillatory pattern (OR 4.65; 95% CI [1.55-16.13]; p=0.0052); and haemoglobin level (OR 0.35; 95% CI [0.21-0.55]; p<0.0001). In patients who had cardiac magnetic resonance, when delayed enhancement >4.6% was detected, a lower response after sacubitril/valsartan therapy was observed as expressed by improvement in ΔVO₂ peak, O₂ pulse, LVEF and N-terminal pro-B-type natriuretic peptide. No significant differences were observed in ΔVO₂/Δ work and VE/VCO₂ slope. Conclusion:Sacubitril/valsartan improves cardiopulmonary functional capacity in HFrEF patients. The presence of myocardial fibrosis on cardiac magnetic resonance is a predictor of response to therapy.

Sacubitril/Valsartan vs. Standard Medical Therapy on Exercise Capacity in HFrEF Patients

Sacubitril/valsartan (Sac/Val) reduces mortality in patients with heart failure with reduced ejection fraction (HFrEF) compared to enalapril. However, its effects on functional capacity remain uncertain; consequently, we sought to compare Sac/Val vs. standard medical therapy, in terms of effects on prognostically significant CPET parameters, in HFrEF patients during a long follow-up period. We conducted a single-center, observational study in an HF clinic; specifically, we retrospectively identified that 12 patients switched to Sac/Val and 13 patients that managed with standard, optimal medical therapy (control group). At each visit, baseline, and follow-up (median time: 16 months; IQ range: 11.5-22), we collected demographic information, medical history, vital signs, cardiopulmonary exercise testing, standard laboratory data, pharmacological treatment information, and echocardiographic parameters. The study's primary end-point was the change from baseline in peak VO2 (adjusted to body weight). We did not observe significant differences between the two study groups at baseline. Similarly, we did not observe any significant differences during the follow-up in mean values of peak VO2 corrected for body weight: Sac/Val baseline: 12.2 ± 4.6 and FU: 12.7 ± 3.3 vs. control group: 13.1 ± 4.2 and 13.0 ± 4.2 mL/kg/min; p = 0.49. No significant treatment differences were observed for changes in VE/VCO2 slope: Sac/Val baseline: 35.4 ± 7.4 and FU: 37.2 ± 13.1 vs. control group: 34.6 ± 9.1 and 34.0 ± 7.3; p = 0.49. In conclusion, after a median follow-up period of 16 months, there was no significant benefit of Sac/Val on peak VO2 and other measures of CPET compared with standard optimal therapy in patients with HFrEF.

The role of the microcirculation and integrative cardiovascular physiology in the pathogenesis of ICU-acquired weakness

Skeletal muscle dysfunction after critical illness, defined as ICU-acquired weakness (ICU-AW), is a complex and multifactorial syndrome that contributes significantly to long-term morbidity and reduced quality of life for ICU survivors and caregivers. Historically, research in this field has focused on pathological changes within the muscle itself, without much consideration for their in vivo physiological environment. Skeletal muscle has the widest range of oxygen metabolism of any organ, and regulation of oxygen supply with tissue demand is a fundamental requirement for locomotion and muscle function. During exercise, this process is exquisitely controlled and coordinated by the cardiovascular, respiratory, and autonomic systems, and also within the skeletal muscle microcirculation and mitochondria as the terminal site of oxygen exchange and utilization. This review highlights the potential contribution of the microcirculation and integrative cardiovascular physiology to the pathogenesis of ICU-AW. An overview of skeletal muscle microvascular structure and function is provided, as well as our understanding of microvascular dysfunction during the acute phase of critical illness; whether microvascular dysfunction persists after ICU discharge is currently not known. Molecular mechanisms that regulate crosstalk between endothelial cells and myocytes are discussed, including the role of the microcirculation in skeletal muscle atrophy, oxidative stress, and satellite cell biology. The concept of integrated control of oxygen delivery and utilization during exercise is introduced, with evidence of physiological dysfunction throughout the oxygen delivery pathway - from mouth to mitochondria - causing reduced exercise capacity in patients with chronic disease (e.g., heart failure, COPD). We suggest that objective and perceived weakness after critical illness represents a physiological failure of oxygen supply-demand matching - both globally throughout the body and locally within skeletal muscle. Lastly, we highlight the value of standardized cardiopulmonary exercise testing protocols for evaluating fitness in ICU survivors, and the application of near-infrared spectroscopy for directly measuring skeletal muscle oxygenation, representing potential advancements in ICU-AW research and rehabilitation.

How Does the Method Used to Measure the VE/VCO2 Slope Affect Its Value? A Cross-Sectional and Retrospective Cohort Study

Cardiopulmonary exercise testing (CPET) was limited to peak oxygen consumption analysis (VO₂peak), and now the ventilation/carbon dioxide production (VE/VCO₂) slope is recognized as having independent prognostic value. Unlike VO₂peak, the VE/VCO₂ slope does not require maximal effort, making it more feasible. There is no consensus on how to measure the VE/VCO₂ slope; therefore, we assessed whether different methods affect its value. This is a retrospective study assessing sociodemographic data, left ventricular ejection fraction, CPET parameters, and indications of patients referred for CPET. The VE/VCO₂ slope was measured to the first ventilatory threshold (VT1-slope), secondary threshold (VT2-slope), and included all test data (full-slope). Of the 697 CPETs analyzed, 308 reached VT2. All VE/VCO₂ slopes increased with age, regardless of test indications. In patients not reaching VT2, the VT1-slope was 32 vs. 36 (p < 0.001) for the full-slope; in those surpassing VT2, the VT1-slope was 29 vs. 33 (p < 0.001) for the VT2-slope and 37 (all p < 0.001) for the full-slope. The mean difference between the submaximal and full-slopes was ±4 units, sufficient to reclassify patients from low to high risk for heart failure or pulmonary hypertension. We conclude that the method used for determining the VE/VCO₂ slope greatly influences the result, the significant variations limiting its prognostic value. The calculation method must be standardized to improve its prognostic value.

Cardiopulmonary exercise testing applied to respiratory medicine: Myths and facts

Cardiopulmonary exercise testing (CPET) remains poorly understood and, consequently, largely underused in respiratory medicine. In addition to a widespread lack of knowledge of integrative physiology, several tenets of CPET interpretation have relevant controversies and limitations which should be appropriately recognized. With the intent to provide a roadmap for the pulmonologist to realistically calibrate their expectations towards CPET, a collection of deeply entrenched beliefs is critically discussed. They include a) the actual role of CPET in uncovering the cause(s) of dyspnoea of unknown origin, b) peak O₂ uptake as the key metric of cardiorespiratory capacity, c) the value of low lactate ("anaerobic") threshold to differentiate cardiocirculatory from respiratory causes of exercise limitation, d) the challenges of interpreting heart rate-based indexes of cardiovascular performance, e) the meaning of peak breathing reserve in dyspnoeic patients, f) the merits and drawbacks of measuring operating lung volumes during exercise, g) how best interpret the metrics of gas exchange inefficiency such as the ventilation-CO₂ output relationship, h) when (and why) measurements of arterial blood gases are required, and i) the advantages of recording submaximal dyspnoea "quantity" and "quality". Based on a conceptual framework that links exertional dyspnoea to "excessive" and/or "restrained" breathing, I outline the approaches to CPET performance and interpretation that proved clinically more helpful in each of these scenarios. CPET to answer clinically relevant questions in pulmonology is a largely uncharted research field: I, therefore, finalize by highlighting some lines of inquiry to improve its diagnostic and prognostic yield.

Heart failure classification based on resting ejection fraction does not display a unique exercise response pattern

BACKGROUND

Heart failure with preserved (HFpEF), mildly reduced (HFmrEF) and reduced (HFrEF) ejection fraction (EF) remains a controversial categorization. Whether these three categories reflect a distinct pattern of exercise limitation in cardiopulmonary exercise testing (CPET) needs to be investigated. We aimed to analyze whether CPET variables differ between all heart failure categories (HF).

METHODS

We analyzed CPET variables of stable HFpEF (n = 123), HFmrEF (n = 31), and HFrEF (n = 153; 74 patients with and 79 patients without left ventricular assist device, LVAD) patients. The association between HF and peak oxygen consumption (VO_2peak) was used as a primary outcome, while the association between HF, oxygen uptake efficiency slope (OUES), and increase of O₂ pulse (ΔO₂ pulse) were analyzed as secondary outcomes.

RESULTS

VO_2peak displayed a consistent decline across all HF categories (19.8 ml ± 6.2/kg/min vs. 17.5 ± 7.9 ml/kg/min vs. 13.7 ± 4.0 ml/kg/min, p < 0.001). OUES only showed differences between HFpEF and HFrEF (1.8 ± 0.6 vs. 1.4 ± 0.5, p < 0.001) as well as HFmrEF and HFrEF (1.9 ± 0.9 vs. 1.4 ± 0.5, p = 0.004). ΔO₂ pulse differed between HFpEF and HFrEF (7.7 ± 3.5 ml/beat/kg*100 vs. 5.5 ± 3.0 ml/beat/kg*100, p < 0.001) as well as HFpEF and HFmrEF (7.7 ± 3.5 ml/beat/kg*100 vs. 6.3 ± 4.1 ml/beat/kg*100, p = 0.049). Outcome variables did not differ between HFrEF with and without LVAD support (VO_2peak: p = 0.364, OUES: p = 0.129, ΔO₂ pulse: p = 0.564).

CONCLUSIONS

HF did not display a distinct CPET profile. Thus, EF-based categorization does not entirely reflect exercise limitations. CPET variables could contribute to better characterize HF phenotypes.

Left atrial dysfunction can independently predict exercise capacity in patients with chronic heart failure who use beta-blockers

BACKGROUND

Beta-blockers are first-line clinical drugs for the treatment of chronic heart failure (CHF). In the guidelines for cardiac rehabilitation, patients with heart failure who do or do not receive beta-blocker therapy have different reference thresholds for maximal oxygen uptake (VO_2max). It has been reported that left atrial (LA) strain can be used to predict VO_2max in patients with heart failure, which can be used to assess exercise capacity. However, most existing studies included patients who did not receive beta-blocker therapy, which could have a heterogeneous influence on the conclusions. For the vast majority of CHF patients receiving beta-blockers, the exact relationship between LA strain parameters and exercise capacity is unclear.

METHODS

This cross-sectional study enrolled 73 patients with CHF who received beta-blockers. All patients underwent a thorough resting echocardiogram and a cardiopulmonary exercise test to obtain VO_2max, which was used to reflect exercise capacity.

RESULTS

LA reservoir strain, LA maximum volume index (LAVI_max), LA minimum volume index (LAVI_min) (P < 0.0001) and LA booster strain (P < 0.01) were all significantly correlated with VO_2max, and LA conduit strain was significantly correlated with VO_2max (P < 0.05) after adjusting for sex, age, and body mass index. LA reservoir strain, LAVI_max, LAVI_min (P < 0.001), and LA booster strain (P < 0.05) were significantly correlated with VO_2max after adjusting for left ventricular ejection fraction, the ratio of transmitral E velocity to tissue Doppler mitral annulus e' velocity (E/e'), and tricuspid annular plane systolic excursion. LA reservoir strain with a cutoff value of 24.9% had a sensitivity of 74% and specificity of 63% for the identification of patients with VO_2max < 16 mL/kg/min.

CONCLUSION

Among CHF patients receiving beta-blocker therapy, resting LA strain is linearly correlated with exercise capacity. LA reservoir strain is a robust independent predictor of reduced exercise capacity among all resting echocardiography parameters.

CLINICAL TRIAL REGISTRATION

This study is a part of the Baduanjin-Eight-Silken-Movement with Self-efficacy Building for Patients with Chronic Heart Failure (BESMILE-HF) trial NCT03180320 (ClinicalTrials.gov, registration date: 08/06/2017).

Prognostic value of cardiopulmonary exercise testing in patients with transthyretin cardiac amyloidosis

The aim of this study is to evaluate the prognostic value of cardiopulmonary testing (CPET) in a cohort of patients with transthyretin cardiac amyloidosis (ATTR-CA). ATTR-CA is associated with a progressive reduction in functional capacity. The prognostic role of CPET parameters and in particular of normalized peak VO2 (%ppVO2) remains to be thoroughly evaluated. In this study, 75 patients with ATTR-CA underwent cardiological evaluation and CPET in a National Referral Center for cardiac amyloidosis (Careggi University Hospital, Florence). Fifty-seven patients (76%) had wild-type ATTR. Median age was 80 (75-83) years, 68 patients (91%) were men. Peak oxygen consumption (14.1 ± 4.1 ml/kg/min) and %ppVO₂ (68.4 ± 18.8%) were blunted. Twenty-seven (36%) patients had an abnormal pressure response to exercise. After a median follow-up of 25 (12-31) months, the composite outcome of death or heart failure hospitalization was registered in 19 (25.3%) patients. At univariate analysis %ppVO₂ was a stronger predictor for the composite outcome than peak VO₂. %ppVO₂ and NT-proBNP remained associated with the composite outcome at multivariate analysis. The optimal predictive threshold for %ppVO₂ was 62% (sensitivity: 71%; specificity: 68%; AUC: 0.77, CI 0.65-0.88). Patients with %ppVO₂ ≤ 62%and NT-proBNP > 3000 pg had a worse prognosis with 1- and 2-year survival of 69 ± 9% and 50 ± 10%, respectively. CPET is a safe and useful prognostic tool in patients with ATTR-CA. CPET may help to identify patients with advanced disease that may benefit from targeted therapy.

Effect of Training on Vascular Function and Repair in Heart Failure With Preserved Ejection Fraction

BACKGROUND

Exercise training improves peak oxygen uptake (V̇O₂peak) in heart failure with preserved ejection fraction (HFpEF). Multiple adaptations have been addressed, but the role of circulating endothelium-repairing cells and vascular function have not been well defined.

OBJECTIVES

The authors investigated effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on vascular function and repair in HFpEF.

METHODS

This study is a subanalysis of the OptimEx-Clin Study randomizing patients with HFpEF (n = 180) to HIIT, MICT, or guideline control. At baseline, 3, and 12 months, the authors measured peripheral arterial tonometry (valid baseline measurement in n = 109), flow-mediated dilation (n = 59), augmentation index (n = 94), and flow cytometry (n = 136) for endothelial progenitor cells and angiogenic T cells. Abnormal values were defined as outside 90% of published sex-specific reference values.

RESULTS

At baseline, abnormal values (%) were observed for augmentation index in 66%, peripheral arterial tonometry in 17%, flow-mediated dilation in 25%, endothelial progenitor cells in 42%, and angiogenic T cells in 18%. These parameters did not change significantly after 3 or 12 months of HIIT or MICT. Results remained unchanged when confining analysis to patients with high adherence to training.

CONCLUSIONS

In patients with HFpEF, high augmentation index was common, but endothelial function and levels of endothelium-repairing cells were normal in most patients. Aerobic exercise training did not change vascular function or cellular endothelial repair. Improved vascular function did not significantly contribute to the V̇O₂peak improvement after different training intensities in HFpEF, contrary to previous studies in heart failure with reduced ejection fraction and coronary artery disease. (Optimizing Exercise Training in Prevention and Treatment of Diastolic Heart Failure [OptimEx-Clin]; NCT02078947).

Sex differences in heart failure patients assessed by combined echocardiographic and cardiopulmonary exercise testing

Background

We aimed to test the differences in peak VO₂ between males and females in patients diagnosed with heart failure (HF), using combined stress echocardiography (SE) and cardiopulmonary exercise testing (CPET).

Methods

Patients who underwent CPET and SE for evaluation of dyspnea or exertional intolerance at our institution, between January 2013 and December 2017, were included and retrospectively assessed. Patients were divided into three groups: HF with preserved ejection fraction (HFpEF), HF with mildly reduced or reduced ejection fraction (HFmrEF/HFrEF), and patients without HF (control). These groups were further stratified by sex.

Results

One hundred seventy-eight patients underwent CPET-SE testing, of which 40% were females. Females diagnosed with HFpEF showed attenuated increases in end diastolic volume index (P = 0.040 for sex × time interaction), significantly elevated E/e' (P < 0.001), significantly decreased left ventricle (LV) end diastolic volume:E/e ratio (P = 0.040 for sex × time interaction), and lesser increases in A-VO₂ difference (P = 0.003 for sex × time interaction), comparing to males with HFpEF. Females diagnosed with HFmrEF/HFrEF showed diminished increases in end diastolic volume index (P = 0.050 for sex × time interaction), mostly after anaerobic threshold was met, comparing to males with HFmrEF/HFrEF. This resulted in reduced increases in peak stroke volume index (P = 0.010 for sex × time interaction) and cardiac output (P = 0.050 for sex × time interaction).

Conclusions

Combined CPET-SE testing allows for individualized non-invasive evaluation of exercise physiology stratified by sex. Female patients with HF have lower exercise capacity compared to men with HF. For females diagnosed with HFpEF, this was due to poorer LV compliance and attenuated peripheral oxygen extraction, while for females diagnosed with HFmrEF/HFrEF, this was due to attenuated increase in peak stroke volume and cardiac output. As past studies have shown differences in clinical outcomes between females and males, this study provides an essential understanding of the differences in exercise physiology in HF patients, which may improve patient selection for targeted therapeutics.

Cardiorespiratory fitness as a vital sign of CVD risk in the COVID-19 era

The severe health consequences of the corona virus disease 2019 (COVID-19) pandemic have been exacerbated by the prevalence of cardiovascular disease (CVD) risk factors, such as physical inactivity, obesity, hypertension, and diabetes. Further, policy decisions during the pandemic augmented unhealthy lifestyle behaviors and health inequalities, likely increasing the global disease burden. Cardiorespiratory fitness (CRF) is a well-established biomarker associated with CVD risk. Emerging data demonstrate that high CRF offers some protection against severe outcomes from COVID-19 infection, highlighting the importance of CRF for population health and the potential for limiting the severity of future pandemics. CRF is best assessed by cardiopulmonary exercise testing (CPET), which will be an important tool for understanding the prolonged pathophysiology of COVID-19, the emergence of long-COVID, and the lasting effects of COVID-19 on CVD risk. Utilization of CRF and CPET within clinical settings should become commonplace because of lessons learned from the COVID-19 pandemic.

The role of cardiopulmonary exercise testing in risk stratification and prognosis of atrial fibrillation: a scoping review of the literature

BACKGROUND

Cardiopulmonary exercise testing (CPET) is a significant tool for evaluating exercise capacity in healthy individuals and in various pulmonary and cardiovascular conditions, quantifying symptoms and predicting outcomes. Atrial fibrillation (AF) poses a significant burden on patients and health systems; a research marathon is ongoing for discovering the pathophysiologic substrate, natural history, prognostic tools and optimal treatment strategies for AF. Among the plethora of variables measured during CPET, there is a series of parameters of interest concerning AF.

METHODS

We conducted a scoping review aiming to identify significant CPET-related parameters linked to AF, as well as indicate the impact of other cardiac disease-related variables. We searched PubMed from its inception to 12 January 2022 for reports underlining the contribution of CPET in the assessment of patients with AF. Only clinical trials, observational studies and systematic reviews were included, while narrative reviews, expert opinions and other forms of manuscripts were excluded.

RESULTS

In our scoping review, we report a group of heterogeneous, thus noteworthy parameters relevant to the potential contribution of CPET in AF. CPET helps phenotype AF populations, evaluates exercise capacity after cardioversion or catheter ablation, and assesses heart rate response to exercise; peak VO₂ and VE/VCO₂, commonly measured indices during CPET, also serve as prognostic tools in patients with AF and heart failure.

CONCLUSIONS

CPET seems to hold a clinically important predictive value for future cardiovascular events both in patients with pre-existing cardiac conditions and in healthy individuals. CPET variables may play a fundamental role in the prediction of future AF-related events.