Heart failure prognosis over time: how the prognostic role of oxygen consumption and ventilatory efficiency during exercise has changed in the last 20 years

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.

(Non)-Exertional Variables of Cardiopulmonary Exercise Testing in Heart Failure with and Without Cardiac Amyloidosis

PURPOSE OF REVIEW

Cardiac amyloidosis (CA) constitutes an important etiology of heart failure with preserved ejection fraction (HFpEF) or heart failure with mildly reduced ejection fraction (HFmrEF). Since patients with CA show early exhaustion, we aimed to investigate whether non-exertional variables of cardiopulmonary exercise testing (CPET) provide additional information in comparison to traditional peak oxygen consumption (VO2peak).

RECENT FINDINGS

We retrospectively investigated CPET variables of patients with HFpEF and HFmrEF with (n = 21) and without (n = 21, HF) CA at comparable age and ejection fraction. Exertional and non-exertional CPET variables as well as laboratory and echocardiographic markers were analyzed. The primary outcome was the difference in CPET variables between groups. The secondary outcome was rehospitalization in patients with CA during a follow-up of 24 months. Correlations between CPET, NTproBNP, and echocardiographic variables were calculated to detect patterns of discrimination between the groups. HF patients with CA were inferior to controls in most exertional and non-exertional CPET variables. Patients with CA were hospitalized more often (p = 0.002), and rehospitalization was associated with VE/VCO2 (p = 0.019), peak oxygen pulse (p = 0.042), the oxygen equivalent at the first ventilatory threshold (p = 0.003), circulatory (p = 0.024), and ventilatory power (p < .001), but not VO2peak (p = 0.127). Higher performance was correlated with lower E/e' and NTproBNP as well as higher resting heart rate and stroke volume in CA. Patients with CA displayed worse non-exertional CPET performance compared to non-CA HF patients, which was associated with rehospitalization. Differences between correlations of resting echocardiography and CPET variables between groups emphasize different properties of exercise physiology despite comparable ejection fraction.

Hemodynamic Response to Exercise Training in Heart Failure With Reduced Ejection Fraction Patients

Background

Supervised exercise training decreases total and cardiac mortality and increases quality of life of heart failure with reduced ejection fraction (HFrEF) patients. However, response to training is variable from one patient to another and factors responsible for a positive response to training remain unclear. The aims of the study were to compare cardiac hemodynamic changes after an exercise training program in responders (R) versus non-responders (NR) HFrEF patients, and to compare different discriminators used to assess response to training.

Methods

Seventy-six HFrEF patients (86% males, 57 ± 12 years) completed an exercise training program for 4 weeks. Patients underwent cardiopulmonary exercise testing (CPET) on a cycle ergometer before and after training. Cardiac hemodynamics were measured by impedance cardiography during CPET. The R and NR groups were classified using the median change in peak oxygen uptake (V̇O2peak).

Results

There were statistically significant differences in V̇O2peak (+35% vs. -1%, P < 0.0001) and in peaks of ventilation (+30% vs. +2%, P < 0.0001), cardiac output (COpeak) (+25% vs. +4%, P < 0.01), systolic blood pressure (+12% vs. +2%, P < 0.05), diastolic blood pressure (+9% vs. +4%, P < 0.05) and heart rate (+8% vs. +1%, P < 0.01) between R and NR after the training program. V̇O2peak was the best discriminator between R and NR (receiver operating characteristic (ROC) area under the curve (AUC) = 0.83, P < 0.0001), followed by COpeak (ROC AUC = 0.77, P < 0.0001).

Conclusion

V̇O2peak is the best discriminator between HFrEF R and NR patients after the training program. Responders showed improvements in peak hemodynamic parameters. These results pave the way for other studies to determine how the individualization of exercise training programs and peak hemodynamic parameters potentially linked to a better positive response status.

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

AIMS

Chronotropic incompetence (CI) is a strong predictor of outcome in heart failure with reduced ejection fraction, however no data on its clinical and prognostic impacts in heart failure with mildly reduced ejection fraction (HFmrEF) are available. Therefore, the study aims to investigate, in a large multicentre HFmrEF cohort, the prevalence of CI as well as its relationship with exercise capacity and its prognostic role over the cardiopulmonary exercise testing (CPET) parameters.

METHODS AND RESULTS

Within the Metabolic Exercise combined with Cardiac and Kidney Indexes (MECKI) database, we analysed data of 864 HFmrEF out of 1164 stable outpatients who performed a maximal CPET at the cycle ergometer and who had no significant rhythm disorders or comorbidities. The primary study endpoint was cardiovascular (CV) death. All-cause death was also explored. Chronotropic incompetence prevalence differed depending on the method (peak heart rate, pHR% vs. pHR reserve, pHRR%) and the cut-off adopted (pHR% from ≤75% to ≤60% and pHRR% ≤ 65% to ≤50%), ranging from 11% to 62%. A total of 84 (9.7%) CV deaths were collected, with 39 (4.5%) occurring within 5 years. At multivariate analysis, both pHR% [hazard ratio 0.97 (0.95-0.99), P < 0.05] and pHRR% [hazard ratio 0.977 (0.961-0.993), P < 0.01] were associated with the primary endpoint. A pHR% ≤ 75% and a pHRR% ≤ 50% represented the most accurate cut-off values in predicting the outcome.

CONCLUSION

The study suggests an association between blunted exercise-HR response, functional capacity, and CV death risk among patients with HFmrEF. Whether the CI presence might be adopted in daily HFmrEF management needs to be addressed in larger prospective studies.

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.

Determinants of exercise performance in heart failure patients with extremely reduced cardiac output and left ventricular assist device

The evaluation of exercise capacity and cardiac output (QC) is fundamental in the management of patients with advanced heart failure (AdHF). QC and peak oxygen uptake (VO2) have a pivotal role in the prognostic stratification and in the definition of therapeutic interventions, including medical therapies and devices, but also specific treatments such as heart transplantation and left ventricular assist device (LVAD) implantation. Due to the intertwined relationship between exercise capacity and daily activities, exercise intolerance dramatically has impact on the quality of life of patients. It is a multifactorial process that includes alterations in central and peripheral haemodynamic regulation, anaemia and iron deficiency, pulmonary congestion, pulmonary hypertension, and peripheral O2 extraction. This paper aims to review the pathophysiological background of exercise limitations in HF patients and to examine the complex physiology of exercise in LVAD recipients, analysing the interactions between the cardiopulmonary system, the musculoskeletal system, the autonomic nervous system, and the pump. We performed a literature review to highlight the current knowledge on this topic and possible interventions that can be implemented to increase exercise capacity in AdHF patients-including administration of levosimendan, rehabilitation, and the intriguing field of LVAD speed changes. The present paper confirms the role of CPET in the follow-up of this peculiar population and the impact of exercise capacity on the quality of life of AdHF patients.

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.

The cardiopulmonary exercise test in the prognostic evaluation of patients with heart failure and cardiomyopathies: the long history of making a one-size-fits-all suit

Cardiopulmonary exercise test (CPET) has become pivotal in the functional evaluation of patients with chronic heart failure (HF), supplying a holistic evaluation both in terms of exercise impairment degree and possible underlying mechanisms. Conversely, there is growing interest in investigating possible multiparametric approaches in order to improve the overall HF risk stratification. In such a context, in 2013, a group of 13 Italian centres skilled in HF management and CPET analysis built the Metabolic Exercise test data combined with Cardiac and Kidney Indexes (MECKI) score, based on the dynamic assessment of HF patients and on some other instrumental and laboratory parameters. Subsequently, the MECKI score, initially developed on a cohort of 2716 HF patients, has been extensively validated as well as challenged with the other multiparametric scores, achieving optimal results. Meanwhile, the MECKI score research group has grown over time, involving up to now a total of 27 centres with an available database accounting for nearly 8000 HF patients. This exciting joint effort from multiple HF Italian centres allowed to investigate different HF research field in order to deepen the mechanisms underlying HF, to improve the ability to identify patients at the highest risk as well as to analyse particular HF categories. Most recently, some of the participants of the MECKI score group started to join the forces in investigating a possible additive role of CPET assessment in the cardiomyopathy setting too. The present study tells the ten-year history of the MECKI score presenting the most important results achieved as well as those projects in the pipeline, this exciting journey being far to be concluded.

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.

International validation of the Metabolic Exercise test data combined with Cardiac and Kidney Indexes (MECKI) score in heart failure

AIMS

Current European heart failure (HF) guidelines suggest the use of risk score: among them, the Metabolic Exercise test data combined with Cardiac and Kidney Indexes (MECKI) score has demonstrated to be one of the most accurate. However, the risk scores are still poorly implemented in clinical practice, also due to the lack of strong evidence regarding their external validation in different populations. Thus, the current study was designed as an external validation test of the MECKI score in an international multicentre setting.

METHODS AND RESULTS

The study cohort consisted of patients diagnosed with HF with reduced ejection fraction (HFrEF) across international centres (not Italian), retrospectively recruited. Collected data included demographics, HF aetiology, laboratory testing, electrocardiogram (ECG), echocardiographic findings, and cardiopulmonary exercise testing (CPET) results as described in the original MECKI score publication. A total of 1042 patients across 8 international centres (7 European and 1 Asian) were included and followed up from 1998 till 2019. Patients were divided according to the calculated MECKI scores into three subgroups: (i) MECKI score <10%, (ii) 10-20%, and (iii) ≥ 20%. Survival analysis comparison among the three MECKI score subgroups showed a worse prognosis in patients with higher MECKI score value: median event-free survival times were 4396 days for MECKI score <10%, 3457 days for 10-20%, and 1022 days for ≥20% (P < 0.0001). Receiver operating characteristic (ROC) curves and area under the ROC curves (AUC) were like those reported in the original internal validation studies.

CONCLUSION

In patients diagnosed with HFrEF, the power of the MECKI score was confirmed in terms of prognosis and risk stratification, supporting its implementation as advised by the HF guidelines.

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.

Reference Values of Cardiopulmonary Exercise Test Parameters in the Contemporary Paediatric Population

BACKGROUND

The evaluation of health status by cardiopulmonary exercise test (CPET) has shown increasing interest in the paediatric population. Our group recently established reference Z-score values for paediatric cycle ergometer VO_2max, applicable to normal and extreme weights, from a cohort of 1141 healthy children. There are currently no validated reference values for the other CPET parameters in the paediatric population. This study aimed to establish, from the same cohort, reference Z-score values for the main paediatric cycle ergometer CPET parameters, apart from VO_2max.

RESULTS

In this cross-sectional study, 909 healthy children aged 5-18 years old underwent a CPET. Linear, quadratic, and polynomial mathematical regression equations were applied to identify the best CPET parameters Z-scores, according to anthropometric parameters (sex, age, height, weight, and BMI). This study provided Z-scores for maximal CPET parameters (heart rate, respiratory exchange ratio, workload, and oxygen pulse), submaximal CPET parameters (ventilatory anaerobic threshold, VE/VCO₂ slope, and oxygen uptake efficiency slope), and maximum ventilatory CPET parameters (tidal volume, respiratory rate, breathing reserve, and ventilatory equivalent for CO₂ and O₂).

CONCLUSIONS

This study defined paediatric reference Z-score values for the main cycle ergometer CPET parameters, in addition to the existing reference values for VO_2max, applicable to children of normal and extreme weights. Providing Z-scores for CPET parameters in the paediatric population should be useful in the follow-up of children with various chronic diseases. Thus, new paediatric research fields are opening up, such as prognostic studies and clinical trials using cardiopulmonary fitness outcomes. Trial registration NCT04876209-Registered 6 May 2021-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04876209 .

Improved Peak Oxygen Uptake Reduces Cardiac Events After 3 Weeks of Inpatient Cardiac Rehabilitation for Chronic Heart Failure Patients

Background: The incidence of heart failure (HF) is increasing, and the mortality from HF remains high in an aging society. Cardiac rehabilitation (CR) programs (CRP) increase oxygen uptake (V̇O₂) and reduce HF rehospitalization and mortality. Therefore, CR is recommended for every HF patient. However, the number of outpatients undergoing CR remains low, with insufficient attendance at CRP sessions. In this study we evaluated the outcomes of 3 weeks of inpatient CRP (3w In-CRP) for HF patients. Methods and Results: This study enrolled 93 HF patients after acute-phase hospitalization between 2019 and 2022. Patients participated in 30 sessions of 3w In-CRP (30 min aerobic exercise twice daily, 5 days/week). Before and after 3w In-CRP, patients underwent a cardiopulmonary exercise test, and cardiovascular (CV) events (mortality, HF rehospitalization, myocardial infarction, and cerebrovascular disease) after discharge were evaluated. After 3w In-CPR, mean (±SD) peak V̇O₂ increased from 11.8±3.2 to 13.7±4.1 mL/min/kg (116.5±22.1%). During the follow-up period (357±292 days after discharge), 20 patients were rehospitalized for HF, 1 had a stroke, and 8 died for any reasons. Proportional hazard and Kaplan-Meier analyses demonstrated that CV events were reduced among patients with a 6.1% improvement in peak V̇O₂ than in patients without any improvement in peak V̇O₂. Conclusions: 3w In-CRP for HF patients improved peak V̇O₂ and reduced CV events in HF patients with a 6.1% improvement in peak V̇O₂.

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.

Influence of exertional oscillatory breathing and its temporal behavior in patients with heart failure and reduced ejection fraction

BACKGROUND

Exertional oscillatory breathing (EOV) represents an emerging prognostic marker in heart failure (HF) patients, however little is known about EOV meaning with respect to its disappearance/persistence during cardiopulmonary exercise test (CPET). The present single-center study evaluated EOV clinical and prognostic impact in a large cohort of reduced ejection fraction HF patients (HFrEF) and, contextually, if a specific EOV temporal behavior might be an addictive risk predictor.

METHODS AND RESULTS

Data from 1.866 HFrEF patients on optimized medical therapy were analysed. The primary cardiovascular (CV) study end-point was cardiovascular death, heart transplantation or LV assistance device (LVAD) implantation at 5-years. For completeness a secondary end-point of total mortality at 5- years was also explored. EOV presence was identified in 251 patients (13%): 142 characterized by EOV early cessation (Group A) and 109 by EOV persistence during the whole CPET (Group B). The entire EOV Group showed worse clinical and functional status than NoEOV Group (n = 1.615) and, within the EOV Group, Group B was characterized by a more severe HF. At CV survival analysis, EOV patients showed a poorer outcome than the NoEOV Group (events 27.1% versus 13.1%, p < 0.001) both unpolished and after matching for main confounders. Instead, no significant differences were found between EOV Group A and B with respect to CV outcome. Conversely the analysis for total mortality failed to be significant.

CONCLUSIONS

Our analysis, albeit retrospective, supports the inclusion of EOV into a CPET-centered clinical and prognostic evaluation of the HFrEF patients. EOV characterizes per se a more advanced HFrEF stage with an unfavorable CV outcome. However, the EOV persistence, albeit suggestive of a more severe HF, does not emerge as a further prognostic marker.

Cardiopulmonary exercise testing and heart failure: a tale born from oxygen uptake

Since 50 years, cardiopulmonary exercise testing (CPET) plays a central role in heart failure (HF) assessment. Oxygen uptake (VO2) is one of the main HF prognostic indicators, then paralleled by ventilation to carbon dioxide (VE/VCO2) relationship slope. Also anaerobic threshold retains a strong prognostic power in severe HF, especially if expressed as a percent of maximal VO2 predicted value. Moving beyond its absolute value, a modern approach is to consider the percentage of predicted value for peak VO2 and VE/VCO2 slope, thus allowing a better comparison between genders, ages, and races. Several VO2 equations have been adopted to predict peak VO2, built considering different populations. A step forward was made possible by the introduction of reliable non-invasive methods able to calculate cardiac output during exercise: the inert gas rebreathing method and the thoracic electrical bioimpedance. These techniques made possible to calculate the artero-venous oxygen content differences (ΔC(a-v)O2), a value related to haemoglobin concentration, pO2, muscle perfusion, and oxygen extraction. The role of haemoglobin, frequently neglected, is however essential being anaemia a frequent HF comorbidity. Finally, peak VO2 is traditionally obtained in a laboratory setting while performing a standardized physical effort. Recently, different wearable ergo-spirometers have been developed to allow an accurate metabolic data collection during different activities that better reproduce HF patients' everyday life. The evaluation of exercise performance is now part of the holistic approach to the HF syndrome, with the inclusion of CPET data into multiparametric prognostic scores, such as the MECKI score.

Correlation between three-dimensional echocardiography and cardiopulmonary fitness in patients with univentricular heart: A cross-sectional multicentre prospective study

BACKGROUND

The prognosis of patients with a functional single ventricle has improved, with better cardiopulmonary fitness, health-related quality of life and survival. Conventional echocardiography remains the first-line technique in single ventricle follow-up. Three-dimensional (3D) echocardiography has shown recent value in congenital cardiology, but its ability to predict functional status in patients with a single ventricle remains unknown.

AIM

To evaluate, in patients with a single ventricle, the association between 3D echocardiography variables and functional status determined by cardiopulmonary fitness.

METHODS

Children and adults with a functional single ventricle were prospectively enrolled in this multicentre study. Cardiopulmonary fitness was assessed by cardiopulmonary exercise test, with measures of maximum oxygen uptake (VO_2max) and ventilatory efficiency (VE/VCO₂ slope). 3D echocardiography was performed with off-line reproducibility analyses, using TomTec Arena™ software. Health-related quality of life was assessed using the SF-36 questionnaire.

RESULTS

A total of 33 patients were screened, and 3D echocardiography analyses were feasible in 22 subjects (mean age 28±9years). 3D echocardiography ejection fraction correlated with percent-predicted VO_2max (r=0.64, P<0.01), VE/VCO₂ slope (r=-0.41, P=0.05), two-dimensional echocardiography ejection fraction (r=0.55, P<0.01) and health-related quality of life physical functioning dimension (r=0.56, P=0.04). 3D echocardiography indexed end-systolic volume correlated with percent-predicted VO_2max (r=-0.45, P=0.03) and VE/VCO₂ slope (r=0.65, P<0.01). 3D echocardiography reproducibility was good.

CONCLUSIONS

Single ventricle ejection fraction and volumes measured by 3D echocardiography correlated with cardiopulmonary fitness, as determined by two main prognostic cardiopulmonary exercise test variables: VO_2max and VE/VCO₂ slope. Despite good reproducibility, 3D echocardiography feasibility remained limited. 3D echocardiography may be of value in single ventricle follow-up, provided that the technique and analysis software are improved.

Impaired aerobic capacity in adolescents and young adults after treatment for cancer or non-malignant haematological disease

PURPOSE

Childhood cancer survivors are at increased risk for cardiovascular disease. Maximal oxygen uptake (VO_2max) is a major determinant of cardiovascular morbidity. The aim of this study was to compare aerobic capacity, measured by cardiopulmonary exercise test (CPET), of adolescents and young adults in remission with that of healthy controls and to identify the predictors of aerobic capacity in this population.

METHOD

This is a controlled cross-sectional study.

RESULTS

A total of 477 subjects (77 in remission and 400 controls), aged from 6 to 25 years, were included, with a mean delay between end of treatment and CPET of 2.9 ± 2.3 years in the remission group. In this group, the mean VO_2max was significantly lower than in controls (37.3 ± 7.6 vs. 43.3 ± 13.1 mL/kg/min, P < 0.01, respectively), without any clinical or echocardiographic evidence of heart failure. The VAT was significantly lower in the remission group (26.9 ± 6.0 mL/kg/min vs. 31.0 ± 9.9 mL/kg/min, P < 0.01, respectively). A lower VO_2max was associated with female sex, older age, higher BMI, radiotherapy, and hematopoietic stem cell transplantation.

CONCLUSION

Impaired aerobic capacity had a higher prevalence in adolescents and young adults in cancer remission. This impairment was primarily related to physical deconditioning and not to heart failure.

TRIAL REGISTRY

NCT04815447.

IMPACT

In childhood cancer survivors, aerobic capacity is five times more impaired than in healthy subjects. This impairment mostly reflects early onset of physical deconditioning. No evidence of heart failure was observed in this population.

The effect of SGLT-2 inhibitors on cardiorespiratory fitness capacity: A systematic review and meta-analysis

Objective: The study aimed to evaluate the effect of sodium-glucose transporter 2 (SGLT-2) inhibitors on various parameters of exercise capacity and provide an evidence-based basis for type 2 diabetes mellitus (T2DM) combined with heart failure (HF) patients or HF patients without T2DM who use SGLT-2 inhibitors to improve cardiorespiratory fitness (CRF). Methods: According to the participant, intervention, comparison, and outcome (PICO) elements, the effects of SGLT-2 inhibitor administration on VO₂ or VO₂peak were researched in this study. Weighted mean difference (WMD) and 95% confidence intervals (CIs) were calculated (random-effects model). Heterogeneity was assessed by the I² test. Results: Six studies were included according to the eligibility criteria: four were RCTs, and two were non-RCTs. Compared with the control group, the merge results of RCTs showed that SGLT-2 inhibitors could significantly increase the VO₂peak (WMD, 2.02 ml kg^-1 min^-1, 95% CI: 0.68-3.37, and p = 0.03; I² = 0% and p = 0.40) and VAT (WMD, 1.57 ml kg^-1 min^-1, 95% CI: 0.06-3.07, and p = 0.04; I² = 0% and p = 0.52) of the obese population, patients with T2DM, and chronic HF patients with or without T2DM. Subgroup analysis showed that SGLT-2 inhibitors improved the VO₂peak in non-HF patients (WMD, 3.57 ml kg^-1 min^-1, 95% CI: 0.87-6.26, and p = 0.009; I² = 4% and p = 0.31) more than in HF patients (WMD, 1.46 ml kg^-1 min^-1, 95% CI: -0.13-3.04, and p = 0.07; I² = 0% and p = 0.81). Moreover, the merge of single-arm studies also indicated that empagliflozin could improve VO₂peak (MD, 1.11 ml kg^-1 min^-1, 95% CI: 0.93-1.30, and p = 0.827, Δ p = 0.000 and I² = 0%) of T2DM patients with chronic HF. Conclusion: Despite the limited number of studies and samples involved, the meta-analysis preliminarily demonstrated that SGLT-2 inhibitors could improve some parameters of exercise capacity (VO₂peak, VAT) in chronic HF patients with or without T2DM and obese individuals, which had a positive effect on promoting cardiopulmonary fitness to help these populations improve their prognosis. Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/#recordDetails], identifier [CRD42020202788].

Usefulness of the predicted percentage ventilatory efficiency for carbon dioxide output during exercise in patients with chronic heart failure

The ventilatory efficiency for carbon dioxide output ([Formula: see text]CO₂) during exercise, as measured by the minute ventilation vs. [Formula: see text]CO₂ slope ([Formula: see text]E vs. [Formula: see text]CO₂ slope), is a powerful prognostic index in patients with chronic heart failure (CHF). This measurement is higher in women than in men, and it increases with age. This study aimed to investigate the usefulness of the predicted value of the percentage [Formula: see text]E vs. [Formula: see text]CO₂ slope (%[Formula: see text]E vs. [Formula: see text]CO₂ slope) as a prognostic index in patients with CHF. A total of 320 patients with CHF and a left ventricular ejection fraction (LVEF) < 45% (male, 85.6%; mean age, 64.6 years) who underwent symptom-limited cardiopulmonary exercise tests using a cycle ergometer were included in the study. The %[Formula: see text]E vs. [Formula: see text]CO₂ was calculated using predictive formulae based on age and sex. Cardiovascular-related death was defined as the primary endpoint. The mean follow-up duration was 7.5 ± 3.3 years. Of 101 patients who died during the study period, 75 experienced cardiovascular-related deaths. The average [Formula: see text]E vs. [Formula: see text]CO₂ slope was 32.8 ± 8.0, and the average %[Formula: see text]E vs. [Formula: see text]CO₂ slope was 119.6 ± 28.2%. The cumulative incidence of cardiovascular-related death after 10 years of follow-up were 44.7% (95% CI 34.4-54.6%) in patients with %[Formula: see text]E vs. [Formula: see text]CO₂ slope > 120 and 15.0% (95% CI 9.4-21.8%) in patients with %[Formula: see text]E vs. [Formula: see text]CO₂ slope ≤ 120. The multivariate Cox regression analysis indicated that a %[Formula: see text]E vs. [Formula: see text]CO₂ slope > 120 was an independent predictor of cardiovascular-related death (adjusted hazard ratio, 3.24; 95% confidence interval 1.65-6.67; p < 0.01). The %[Formula: see text]E vs. [Formula: see text]CO₂ slope can be used for risk stratification in patients with CHF and an LVEF < 45%.

Optimizing exercise testing‐based risk stratification to predict poor prognosis after acute heart failure

AIMS

The timely selection of severe heart failure (HF) patients for cardiac transplantation and advanced HF therapy is challenging. Peak oxygen consumption (VO₂ ) values obtained by the cardiopulmonary exercise testing are used to determine the transplant recipient list. This study reassessed the prognostic predictability of peak VO₂ and compared it with the Heart Failure Survival Score (HFSS) in the modern optimized guideline-directed medical therapy (GDMT) era.

METHODS AND RESULTS

We retrospectively selected 377 acute HF patients discharged from the hospital. The primary outcome was a composite of all-cause mortality, or urgent cardiac transplantation. We divided these patients into the more GDMT (two or more types of GDMT) and less GDMT groups (fewer than two types of GDMT) and compared the performance of their peak VO₂ and HFSS in predicting primary outcomes. The median follow-up period was 3.3 years. The primary outcome occurred in 57 participants. Peak VO₂ outperformed HFSS when predicting 1 year (0.81 vs. 0.61; P = 0.017) and 2 year (0.78 vs. 0.58; P < 0.001) major outcomes. The cutoff peak VO₂ for predicting a 20% risk of a major outcome within 2 years was 10.2 (11.8-7.0) for the total cohort. Multivariate Cox regression analyses showed that peak VO₂ , sodium, previous implantable cardioverter defibrillator (ICD) implantation, and estimated glomerular filtration rate were significant predictors of major outcomes.

CONCLUSIONS

Optimizing the cutoff value of peak VO₂ is required in the current GDMT era for advanced HF therapy. Other clinical factors such as ICD use, hyponatraemia, and chronic kidney disease could also be used to predict poor prognosis. The improvement of resource allocation and patient outcomes could be achieved by careful selection of appropriate patients for advanced HF therapies, such as cardiac transplantation.

The Pre-Discharge Oxygen Uptake Efficiency Slope Predicts One-Year Cardiovascular Events in Acute Decompensated Heart Failure Patients

(1) Background: Heart failure is a complex disease leading to functional disability. Cardiopulmonary exercise testing (CPET) is the gold standard in assessing aerobic capacity and formulating function-based prognostic stratification; however, patients with acute heart failure after medical treatment usually remain with markedly reduced exercise capacity, leading to early termination of CPET with submaximal testing results. The current study aimed to assess the cardiorespiratory fitness and characteristics of CPET variables of patients after acute heart failure treatment and determine potential CPET variables with prognostic value. (2) Methods: We recruited patients during hospitalization after management of acute heart failure, and pre-discharge CPET was performed. All enrolled patients were followed for one year for major adverse cardiovascular events (MACE). (3) Results: 85 patients were enrolled, with average left ventricular ejection fraction of 30.52%, and peak oxygen consumption of 10.85 mL/min/kg at baseline. The one-year MACE was 50%. Oxygen uptake efficiency slope (OUES) was a significant event predictor, with lower one-year MACE in those with OUES ≥ 1.25 (p < 0.001). Cox regression analysis showed a 5.421-fold increased risk of MACE in those with OUES < 1.25 (p = 0.004). (4) Conclusions: The current results suggested OUES is a significant prognostic indicator in patients with acute heart failure. This also emphasized the critical role of CPET in patients with heart failure for prognostic stratification.

Capacidade Preditiva dos Parâmetros do Teste de Esforço Cardiopulmonar em Pacientes com Insuficiência Cardíaca em Terapia de Ressincronização Cardíaca

Fundamento

Há evidências sugerindo que um corte do pico de consumo de oxigênio (pVO₂) de 10ml/kg/min fornece uma estratificação de risco mais precisa em pacientes com Terapia de Ressincronização Cardíaca (TRC).

Objetivo

Comparar o poder prognóstico de vários parâmetros do teste cardiopulmonar de exercício (TCPE) nesta população e avaliar a capacidade discriminativa dos valores de corte de pVO₂ recomendados pelas diretrizes.

Métodos

Avaliação prospectiva de uma série consecutiva de pacientes com insuficiência cardíaca (IC) com fração de ejeção do ventrículo esquerdo ≤40%. O desfecho primário foi um composto de morte cardíaca e transplante cardíaco urgente (TC) nos primeiros 24 meses de acompanhamento, e foi analisado por vários parâmetros do TCPE para a maior área sob a curva (AUC) no grupo TRC. Uma análise de sobrevida foi realizada para avaliar a estratificação de risco fornecida por vários pontos de corte diferentes. Valores de p < 0,05 foram considerados significativos.

Resultados

Um total de 450 pacientes com IC, dos quais 114 possuíam aparelho de TRC. Esses pacientes apresentaram um perfil de risco basal mais alto, mas não houve diferença em relação ao desfecho primário (13,2% vs 11,6%, p = 0,660). A pressão expiratória de dióxido de carbono no limiar anaeróbico (P_ETCO_2AT) teve o maior valor de AUC, que foi significativamente maior do que o de pVO₂ no grupo TRC (0,951 vs 0,778, p = 0,046). O valor de corte de pVO2 atualmente recomendado forneceu uma estratificação de risco precisa nesse cenário (p <0,001), e o valor de corte sugerido de 10 ml/min/kg não melhorou a discriminação de risco em pacientes com dispositivos (p = 0,772).

Conclusão

A P_ETCO_2AT pode superar o poder prognóstico do pVO₂ para eventos adversos em pacientes com TRC. O ponto de corte de pVO₂ recomendado pelas diretrizes atuais pode estratificar precisamente o risco dessa população.

The Impact of Oxygen Pulse and Its Curve Patterns on Male Patients with Heart Failure, Chronic Obstructive Pulmonary Disease, and Healthy Controls-Ejection Fractions, Related Factors and Outcomes

Oxygen pulse (O2P) is a function of stroke volume and cellular oxygen extraction and O2P curve pattern (O2PCP) can provide continuous measurements of O2P. However, measurements of these two components are difficult during incremental maximum exercise. As cardiac function is evaluated using ejection fraction (EF) according to the guidelines and EF can be obtained using first-pass radionuclide ventriculography, the aim of this study was to investigate associations of O2P%predicted and O2PCP with EF in patients with heart failure with reduced or mildly reduced ejection fraction (HFrEF/HFmrEF) and chronic obstructive pulmonary disease (COPD), and also in normal controls. This was a prospective observational cross-sectional study. Correlations of resting left ventricular EF, dynamic right and left ventricular EFs and outcomes with O2P% and O2PCP across the three participant groups were analyzed. A total of 237 male subjects were screened and 90 were enrolled (27 with HFrEF/HFmrEF, 30 with COPD and 33 normal controls). O2P% and the proportions of the three types of O2PCP were similar across the three groups. O2P% reflected dynamic right and left ventricular EFs in the control and HFrEF/HFmrEF groups, but did not reflect resting left ventricular EF in all participants. O2PCP did not reflect resting or dynamic ventricular EFs in any of the subjects. A decrease in O2PCP was significantly related to nonfatal cardiac events in the HFrEF/HFmrEF group (log rank test, p = 0.01), whereas O2P% and O2PCP did not predict severe acute exacerbations of COPD. The findings of this study may clarify the utility of O2P and O2PCP, and may contribute to the currently used interpretation algorithm and the strategy for managing patients, especially those with HFrEF/HFmrEF. (Trial registration number NCT05189301.).

Peak oxygen uptake is a strong prognostic predictor for pulmonary hypertension due to left heart disease

Background

Pulmonary hypertension in left heart disease (PH-LHD), which includes combined post- and precapillary PH (Cpc-PH) and isolated postcapillary PH (Ipc-PH), differs significantly in prognosis. We aimed to assess whether cardiopulmonary exercise testing (CPET) predicts the long-term survival of patients with PH-LHD.

Methods

A single-center observational cohort enrolled 89 patients with PH-LHD who had undergone right heart catherization and CPET (mean pulmonary arterial pressure > 20 mm Hg and pulmonary artery wedge pressure ≥ 15 mm Hg) between 2013 and 2021. A receiver operating characteristic curve was plotted to determine the cutoff value of all-cause death. Survival was estimated using the Kaplan–Meier method and analyzed using the log-rank test. The Cox proportional hazards model was performed to determine the association between CPET and all-cause death.

Results

Seventeen patients died within a mean of 2.2 ± 1.3 years. Compared with survivors, nonsurvivors displayed a significantly worse 6-min walk distance, workload, exercise time and peak oxygen consumption (VO₂)/kg with a trend of a lower oxygen uptake efficiency slope (OUES) adjusted by Bonferroni’s correction. Multivariate Cox regression revealed that the peak VO₂/kg was significantly associated with all-cause death after adjusting for Cpc-PH/Ipc-PH. Compared with Cpc-PH patients with a peak VO₂/kg ≥ 10.7 ml kg⁻¹ min⁻¹, Ipc-PH patients with a peak VO₂/kg < 10.7 ml kg⁻¹ min⁻¹ had a worse survival (P < 0.001).

Conclusions

The peak VO₂/kg is independently associated with all-cause death in patients with PH-LHD. The peak VO₂/kg can also be analyzed together with Cpc-PH/Ipc-PH to better indicate the prognosis of patients with PH-LHD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02574-0.

Real world comparison of spironolactone and eplerenone in patients with heart failure

AIMS

In the absence of previous direct comparative studies, we aimed to evaluate the effectiveness of spironolactone and eplerenone in patients with heart failure and reduced ejection fraction (HFrEF) in a real-world clinical setting.

METHODS

Using Fine-Gray´s competing risk regression, we compared the clinical outcomes of 293 patients with chronic HF and left ventricular ejection fraction <40% treated with eplerenone and 293 propensity-score matched individuals treated with spironolactone. Study subjects were selected from a prospective cohort of 1404 ambulatory patients with HFrEF seen since 2010 to 2019 in a single specialized HF clinic, among which 992 received a mineralocorticoid receptor antagonist at baseline. Median follow-up was 3.95 years.

RESULTS

No statistically significant differences between patients treated with eplerenone versus spironolactone were observed with regard to the risk of the primary composite end-point cardiovascular death or HF hospitalization (HR 0.95; 95% CI 0.73-1.23; p= 0.677). However, eplerenone use was associated to lower cardiovascular mortality (HR 0.55; 95% CI 0.35-0.85; p= 0.008) and lower all-cause mortality (HR 0.67; 95% CI 0.47-0.95; p= 0.027). The incidence of drug suspension due to side effects (HR 0.58, 95% CI 0.40-0.85; p= 0.005) and drug suspension due to any reason (HR 0.70, 95% CI 0.51-0.97; p= 0.033) were lower among patients treated with eplerenone.

CONCLUSIONS

In this observational, real-world, propensity-score matched study of patients with HFrEF, eplerenone was associated to lower cardiovascular mortality and lower all-cause mortality than spironolactone.

Patient selection for heart transplant: balancing risk

PURPOSE OF REVIEW

Heart failure incidence continues to rise despite a relatively static number of available donor hearts. Selecting an appropriate heart transplant candidate requires evaluation of numerous factors to balance patient benefit while maximizing the utility of scarce donor hearts. Recent research has provided new insights into refining recipient risk assessment, providing additional tools to further define and balance risk when considering heart transplantation.

RECENT FINDINGS

Recent publications have developed models to assist in risk stratifying potential heart transplant recipients based on cardiac and noncardiac factors. These studies provide additional tools to assist clinicians in balancing individual risk and benefit of heart transplantation in the context of a limited donor organ supply.

SUMMARY

The primary goal of heart transplantation is to improve survival and maximize quality of life. To meet this goal, a careful assessment of patient-specific risks is essential. The optimal approach to patient selection relies on integrating recent prognostication models with a multifactorial assessment of established clinical characteristics, comorbidities and psychosocial factors.

ACUTE TRANSCRANIAL DIRECT CURRENT STIMULATION (tDCS) IMPROVES VENTILATORY VARIABILITY AND AUTONOMIC MODULATION IN RESISTANT HYPERTENSIVE PATIENTS

Here, we assessed the impact of one session of transcranial direct current stimulation (tDCS) or SHAM (20 min, each) on ventilatory responses to cardiopulmonary exercise test, central and peripheral blood pressure (BP), and autonomic modulation in resistant hypertensive (RHT) patients. RHT subjects (n = 13) were randomly submitted to SHAM and tDCS crossing sessions (1 week of "washout"). Patients and a technician who set the tDCS/Sham room up were both blind. After brain stimulation, patients were submitted to a cardiopulmonary exercise test to evaluate ventilatory and cardiovascular response to exercise. Hemodynamic (Finometer®, Beatscope), and autonomic variables were measured at baseline (before tDCS/Sham) and after incremental exercise. RESULTS: Our study shows that tDCS condition improved heart rate recovery, VO2 peak, and vagal modulation (after cardiopulmonary exercise test); attenuated the ventilatory variability response, central and peripheral blood pressure well as sympathetic modulation (after cardiopulmonary exercise test) in comparison with SHAM. These data suggest that acute tDCS sessions prevented oscillatory ventilation behavior during the cardiopulmonary exercise test and mitigated the increase of systolic blood pressure in RHT patients. After the exercise test, tDCS promotes better vagal reentry and improved autonomic modulation, possibly reducing central blood pressure and aortic augmentation index compared to SHAM. Brazilian Registry of Clinical Trials (ReBEC): https://ensaiosclinicos.gov.br/rg/RBR-8n7c9p.

A Model for the Prediction of Mortality and Hospitalization in Chinese Heart Failure Patients

Background: Although many risk prediction models have been released internationally, the application of these models in the Chinese population still has some limitations.

Aims: The purpose of the study was to establish a heart failure (HF) prognosis model suitable for the Chinese population.

Methods: According to the inclusion criteria, we included patients with chronic heart failure (CHF) who were admitted to the Department of Cardiac Rehabilitation of Tongji Hospital from March 2007 to December 2018, recorded each patient's condition and followed up on the patient's re-admission and death. All data sets were randomly divided into derivation and validation cohorts in a ratio of 7/3. Least absolute shrinkage and selection operator regression and Cox regression were used to screen independent predictors; a nomogram chart scoring model was constructed and validated.

Results: A total of 547 patients were recruited in this cohort, and the median follow-up time was 519 days. The independent predictors screened out by the derivation cohort included age, atrial fibrillation (AF), percutaneous coronary intervention (PCI), diabetes mellitus (DM), peak oxygen uptake (peak VO₂), heart rate at the 8th minute after the cardiopulmonary exercise peaked (HR8min), C-reaction protein(CRP), and uric acid (UA). The C indexes values of the derivation and the validation cohorts were 0.69 and 0.62, respectively, and the calibration curves indicate that the model's predictions were in good agreement with the actual observations.

Conclusions: We have developed and validated a multiple Cox regression model to predict long-term mortality and readmission risk of Chinese patients with CHF.

Registration Number: ChicTR-TRC-00000235.

Predicting mortality for patients with heart failure beyond oxygen consumption: a prognostic risk score

Cardiopulmonary exercise test (CPET) is a crucial tool for the functional evaluation of cardiac patients. We hypothesized that maximal oxygen consumption (V̇o_2max) and ventilatory efficiency-minute ventilation to carbon dioxide production (V̇e/V̇co₂) slope are not the only parameters of CPET able to predict major cardiac events (mortality or cardiac transplantation urgently or elective). We aimed to identify the best CPET predictors of major cardiac events in patients with severe chronic heart failure and to propose an integrated score that could be applied for their prognostic evaluation. We evaluated 140 patients with chronic heart failure who underwent CPET between 2011 and 2019. Major cardiac events were evaluated during follow-up. Univariate and multivariate logistic regression analyses were applied to study the predictive value of different clinical, echocardiographic, and CPET parameters in relation to the major cardiac events. A score was generated, and c-statistic was used for the comparisons. Thirty-nine patients (27.9%) died or underwent cardiac transplantation over a median follow-up of 48 mo. Five parameters (maximal workload, breathing reserve, left ventricular ejection fraction, diastolic dysfunction, and nonidiopathic cardiomyopathy) were used to generate a risk score that had better risk discrimination than the New York Heart Association dyspnea scale, V̇o_2max, V̇e/V̇co₂ slope > 35 alone, and combined V̇o_2max and V̇e/V̇co₂ slope (P = 0.009, 0.004, <0.001, and 0.005, respectively) in predicting major cardiac events. A composite score of CPET and clinical/echocardiographic data is more reliable than the single use of V̇o_2max or combined with V̇e/V̇co₂ slope to predict major cardiac events.NEW & NOTEWORTHY This is a cohort study with a follow-up of maximum of 8 years of patients with chronic heart failure that demonstrates a simple integrated score consisting of CPET (breathing reserve, workload at maximal exercise), echocardiographic (LVEF, diastolic dysfunction), and clinical (etiology of cardiac disease) data. The generated score was a better predictor of major cardiac events (mortality or cardiac transplantation) than Weber classification (V̇o_2max classification) or NYHA functional class as single factors.

A randomized clinical trial on the short-term effects of 12-week sacubitril/valsartan vs. enalapril on peak oxygen consumption in patients with heart failure with reduced ejection fraction: results from the ACTIVITY-HF study

AIMS

ACTIVITY-HF was a randomized, double-blind, active-controlled study, which assessed the short-term effect of sacubitril/valsartan compared with the active comparator enalapril on improving maximal exercise capacity in patients with heart failure with reduced ejection fraction (HFrEF).

METHODS AND RESULTS

A total of 201 ambulatory patients with HFrEF (left ventricular ejection fraction ≤ 40%, New York Heart Association class III) across 34 centres in Germany were randomized (1:1) to receive sacubitril/valsartan 97/103 mg bid (n = 103) or enalapril 10 mg bid (n = 98). The primary endpoint of the study was the change from baseline in peak oxygen consumption (VO₂ ; adjusted to body weight) after 12 weeks, and the key secondary endpoint was change from baseline in peak VO₂ after 6 weeks. The study population was predominantly male (81.1%) with a mean age of 66.9 years and a body mass index of 29.4 kg/m² . Change in peak VO₂ from baseline to Week 12 was similar between sacubitril/valsartan and enalapril groups [least squares mean difference: 0.32 mL/min/kg; 95% confidence interval (CI) -0.21, 0.85; P = 0.2327]. Similarly, no significant differences were observed between the two treatment groups in minute ventilation to carbon dioxide production slope, exercise capacity at first ventilatory threshold or Borg scale at either Week 6 or Week 12. Change in heart rate at first ventilatory threshold was lower in the sacubitril/valsartan group compared with the enalapril group at Week 12 (mean -3.75 bpm; 95% CI -7.03, -0.48; P = 0.0248). The safety of sacubitril/valsartan was comparable to enalapril.

CONCLUSION

In patients with HFrEF, short-term treatment with sacubitril/valsartan for 12 weeks did not result in significant benefits on peak VO₂ when compared with enalapril.

Efficacy and Safety of Different Aerobic Exercise Intensities in Patients With Heart Failure With Reduced Ejection Fraction: Design of a Multicenter Randomized Controlled Trial (HF-EI Trial)

Background: Heart failure (HF) is one of the major causes of mortality worldwide, representing the terminal stage of several cardiovascular diseases. Exercise-based rehabilitation is a beneficial therapy for patients with chronic heart failure (CHF). However, there is a lack of specific guidance on clinical decision-making regarding optimal exercise intensity. It is necessary to optimize the clinical recommendations for HF exercises. We will evaluate the efficacy and safety of different aerobic exercise intensities in patients with heart failure with reduced ejection fraction (HFrEF): the HF-EI trial. This trial aims to assess the appropriate exercise intensity for patients with HFrEF.

Methods: After a baseline assessment to determine the safety of exercise, 180 patients will be randomly assigned to supervised high-intensity exercise training (ET) group, supervised moderate intensity training (MIT) group, and control group at a ratio of 1:1:1. Patients randomly receiving high intensity training (HIT) undergo supervised ET (3 times/week, 30 min) for aerobic endurance at 70% peak oxygen consumption (peak VO₂) intensity for 12 weeks. The MIT patients will perform supervised aerobic ET (3 times/week, 35–42 min) at the anaerobic threshold (AT) intensity for 12 weeks. The control group will continue to maintain their daily activities and will not receive ET. During the baseline and follow-up period, physical examination, laboratory tests, cardiology diagnostic tests, cardiopulmonary exercise tests (CPET), 6-min walk distance (6MWD), scale scores, exercise steps, medications, and clinical events will be monitored. Throughout the research, sport bracelets and patient diaries will be used to monitor and record overall physical activity, training courses, and compliance.

Discussion: The HF-EI trial will evaluate the effects of different aerobic exercise intensities on peak VO₂, quality of life (QoL), and clinical events among patients with HFrEF. The findings of this trial will provide a basis for formulating exercise prescriptions for patients with HFrEF.

Clinical Trial Registration:http://www.chictr.org.cn/, identifier: ChiCTR2000036381.

Listing Criteria for Heart Transplant: Role of Cardiopulmonary Exercise Test and of Prognostic Scores

Patients with advanced heart failure (AdHF) have a reduced quality of life and poor prognosis. A heart transplant (HT) is an effective treatment for such patients. Still, because of a shortage of donor organs, the final decision to place a patient without contraindications on the HT waiting list is based on detailed risk-benefit analysis. Cardiopulmonary exercise tests (CPETs) play a pivotal role in guiding selection in patients with AdHF considered for an HT. Furthermore, several validated multivariable predicting scores obtained through various techniques, including the CPETs, are available and part of the decision-making process for HT listing.

Proportional Assist Ventilation Improves Leg Muscle Reoxygenation After Exercise in Heart Failure With Reduced Ejection Fraction

Background

Respiratory muscle unloading through proportional assist ventilation (PAV) may enhance leg oxygen delivery, thereby speeding off-exercise oxygen uptake ( V . ⁢ O 2 ) kinetics in patients with heart failure with reduced left ventricular ejection fraction (HFrEF).

Methods

Ten male patients (HFrEF = 26 ± 9%, age 50 ± 13 years, and body mass index 25 ± 3 kg m²) underwent two constant work rate tests at 80% peak of maximal cardiopulmonary exercise test to tolerance under PAV and sham ventilation. Post-exercise kinetics of V . ⁢ O 2 , vastus lateralis deoxyhemoglobin ([deoxy-Hb + Mb]) by near-infrared spectroscopy, and cardiac output (Q _T ) by impedance cardiography were assessed.

Results

PAV prolonged exercise tolerance compared with sham (587 ± 390 s vs. 444 ± 296 s, respectively; p = 0.01). PAV significantly accelerated V . ⁢ O 2 recovery (τ = 56 ± 22 s vs. 77 ± 42 s; p < 0.05), being associated with a faster decline in Δ[deoxy-Hb + Mb] and Q _T compared with sham (τ = 31 ± 19 s vs. 42 ± 22 s and 39 ± 22 s vs. 78 ± 46 s, p < 0.05). Faster off-exercise decrease in Q _T with PAV was related to longer exercise duration (r = -0.76; p < 0.05).

Conclusion

PAV accelerates the recovery of central hemodynamics and muscle oxygenation in HFrEF. These beneficial effects might prove useful to improve the tolerance to repeated exercise during cardiac rehabilitation.

Effects of coronary sinus Reducer implantation on oxygen kinetics in patients with refractory angina

AIMS

Refractory angina is still a major public health problem. The coronary sinus Reducer (CSR) has recently been introduced as an alternative treatment to reduce symptoms in these patients. The aim of this study was to investigate objective improvements in effort tolerance and oxygen kinetics as assessed by cardiopulmonary exercise testing (CPET) in patients suffering from refractory angina undergoing CSR implantation.

METHODS AND RESULTS

In this multicentre prospective study, patients with chronic refractory angina undergoing CSR implantation were scheduled for CPET before the index procedure and at six-month follow-up. The main endpoints of this analysis were improvements in VO2 max and in VO2 at the anaerobic threshold (AT). Clinical events and improvements in symptoms were also recorded. A total of 37 patients formed the study population. The CSR implantation procedure was successful and without complications in all. At follow-up CPET, significant improvement in VO2 max (+0.97 ml/kg/min [+11.3%]; 12.2±3.6 ml/kg/min at baseline vs 13.2±3.7 ml/kg/min, p=0.026), and workload (+12.9 [+34%]; 68±28 W vs 81±49 W, p=0.05) were observed, with non-significant differences in VO2 at the AT (9.84±3.4 ml/kg/min vs 10.74±3.05 ml/kg/min, p=0.06). Canadian Cardiovascular Society (CCS) grade improved from a mean of 3.2±0.5 to 1.6±0.8 (p<0.01), and significant benefits in all Seattle Angina Questionnaire variables were shown.

CONCLUSIONS

In patients with obstructive coronary artery disease suffering from refractory angina, the implantation of a CSR was associated with objective improvement in exercise capacity and oxygen kinetics at CPET, suggesting a possible reduction of myocardial ischaemia.

Minute ventilation/carbon dioxide production in chronic heart failure

In chronic heart failure, minute ventilation (V'_E) for a given carbon dioxide production (V'_CO2 ) might be abnormally high during exercise due to increased dead space ventilation, lung stiffness, chemo- and metaboreflex sensitivity, early metabolic acidosis and abnormal pulmonary haemodynamics. The V'_E versus V'_CO2 relationship, analysed either as ratio or as slope, enables us to evaluate the causes and entity of the V'_E/perfusion mismatch. Moreover, the V'_E axis intercept, i.e. when V'_CO2 is extrapolated to 0, embeds information on exercise-induced dead space changes, while the analysis of end-tidal and arterial CO₂ pressures provides knowledge about reflex activities. The V'_E versus V'_CO2 relationship has a relevant prognostic power either alone or, better, when included within prognostic scores. The V'_E versus V'_CO2 slope is reported as an absolute number with a recognised cut-off prognostic value of 35, except for specific diseases such as hypertrophic cardiomyopathy and idiopathic cardiomyopathy, where a lower cut-off has been suggested. However, nowadays, it is more appropriate to report V'_E versus V'_CO2 slope as percentage of the predicted value, due to age and gender interferences. Relevant attention is needed in V'_E versus V'_CO2 analysis in the presence of heart failure comorbidities. Finally, V'_E versus V'_CO2 abnormalities are relevant targets for treatment in heart failure.

Revisiting and Implementing the Weber and Ventilatory Functional Classifications in Heart Failure by Cardiopulmonary Imaging Phenotyping

Background

In heart failure, the exercise gas exchange Weber (A to D) and ventilatory classifications (VC‐1 to VC‐4) historically define disease severity and prognosis. However, their applications in the modern heart failure population of any left ventricular ejection fraction combined with hemodynamics are undefined. We aimed at revisiting and implementing these classifications by cardiopulmonary exercise testing imaging.

Methods and Results

269 patients with heart failure with reduced (n=105), mid‐range (n=88) and preserved (n=76) ejection fraction underwent cardiopulmonary exercise testing imaging, primarily assessing the cardiac output (CO), mitral regurgitation, and mean pulmonary arterial pressure (mPAP)/CO slope. Within both classes, a progressively lower exercise CO, higher mPAP/CO slopes, and mitral regurgitation (P<0.01 all) were observed. After adjustment for age and sex, Cox proportional hazard regression analyses showed that Weber (hazard ratio [HR], 2.9; 95% CI, 1.8–4.7; P<0.001) and ventilatory classes (HR, 1.4; 95% CI, 1.1–2.0; P=0.017) were independently associated with outcome. The best stratification was observed when combining Weber (A/B or C/D) with severe ventilation inefficiency (VC‐4) (HR, 2.7; 95% CI, 1.6–4.8; P<0.001). At multivariable analysis the best hemodynamic determinants of peak oxygen consumption and ventilation to carbon dioxide production slope were CO (β‐coefficient, 0.72±0.16; P<0.001) and mPAP/CO slope (β‐coefficient, 0.72±0.16; P<0.001), respectively.

Conclusions

In the contemporary heart failure population, the Weber and ventilatory classifications maintain their prognostic ability, especially when combined. Exercise CO and mPAP/CO slope are the best predictors of peak oxygen consumption and ventilation to carbon dioxide production slope classifications representing the main targets of interventions to impact functional class and, likely, event rate.

Responses to exercise training in patients with heart failure. Analysis by oxygen transport steps

BACKGROUND

Exercise training (ET) increases exercise tolerance, improves quality of life and likely the prognosis in heart failure patients with reduced ejection fraction (HFrEF). However, some patients do not improve, whereas exercise training response is still poorly understood. Measurement of cardiac output during cardiopulmonary exercise test might allow ET response assessment according to the different steps of oxygen transport.

METHODS

Fifty-three patients with HFrEF (24 with ischemic cardiomyopathy (ICM) and 29 with dilated cardiomyopathy (DCM) had an aerobic ET. Before and after ET program, peak oxygen consumption (VO_2peak) and cardiac output using thoracic impedancemetry were measured. Oxygen convection (QO_2peak) and diffusion (DO₂) were calculated using Fick's principle and Fick's simplified law. Patients were considered as responders if the gain was superior to 10%.

RESULTS

We found 55% VO_2peak responders, 62% QO_2peak responders and 56% DO₂ responders. Four patients did not have any response. None baseline predictive factor for VO_2peak response was found. QO_2peak response was related to exercise stroke volume (r = 0.84), cardiac power (r = 0.83) and systemic vascular resistance (SVR_peak) (r = -0.42) responses. Cardiac power response was higher in patients with ICM than in those with DCM (p < 0.05). Predictors of QO2_peak response were low baseline exercise stroke volume and ICM etiology. Predictors of DO₂ response were higher baseline blood creatinine and prolonged training.

CONCLUSION

The analysis of the response to training in patients with HFrEF according to the different steps of oxygen transport revealed different phenotypes on VO_2peak responses, namely responses in either oxygen convection and/or diffusion.

Cost-Effectiveness of a Small Intrapericardial Centrifugal Left Ventricular Assist Device

Supplemental Digital Content is available in the text.

There is limited data on the cost-effectiveness of continuous-flow left ventricular assist devices (LVAD) in the United States particularly for the bridge-to-transplant indication. Our objective is to study the cost-effectiveness of a small intrapericardial centrifugal LVAD compared with medical management (MM) and subsequent heart transplantation using the respective clinical trial data. We developed a Markov economic framework. Clinical inputs for the LVAD arm were based on prospective trials employing the HeartWare centrifugal-flow ventricular assist device system. To better assess survival in the MM arm, and in the absence of contemporary trials randomizing patients to LVAD and MM, estimates from the Seattle Heart Failure Model were used. Costs inputs were calculated based on Medicare claim analyses and when appropriate prior published literature. Time horizon was lifetime. Costs and benefits were appropriately discounted at 3% per year. The deterministic cost-effectiveness analyses resulted in $69,768 per Quality Adjusted Life Year and $56,538 per Life Year for the bridge-to-transplant indication and $102,587 per Quality Adjusted Life Year and $87,327 per Life Year for destination therapy. These outcomes signify a substantial improvement compared with prior studies and re-open the discussion around the cost-effectiveness of LVADs.

The MECKI score initiative: Development and state of the art

The high morbidity and poor survival rates associated with chronic heart failure still represent a big challenge, despite improvements in treatments and the development of new therapeutic opportunities. The prediction of outcome in heart failure is gradually moving towards a multiparametric approach in order to obtain more accurate models and to tailor the prognostic evaluation to the individual characteristics of a single subject. The Metabolic Exercise test data combined with Cardiac and Kidney Indexes (MECKI) score was developed 10 years ago from 2715 patients and subsequently validated in a different population. The score allows an accurate evaluation of the risk of heart failure patients using only six variables that include the evaluation of the exercise capacity (peak oxygen uptake and ventilation/CO₂ production slope), blood samples (haemoglobin, Na⁺, Modification of Diet in Renal Disease) and echocardiography (left ventricular ejection fraction). Over the following years, the MECKI score was tested taking into account therapies and specific markers of heart failure, and it proved to be a simple, useful tool for risk stratification and for therapeutic strategies in heart failure patients. The close connection between the centres involved and the continuous updating of the data allow the participating sites to propose substudies on specific subpopulations based on a common dataset and to put together and develop new ideas and perspectives.

Heart failure in the last year: progress and perspective

Research about heart failure (HF) has made major progress in the last years. We give here an update on the most recent findings. Landmark trials have established new treatments for HF with reduced ejection fraction. Sacubitril/valsartan was superior to enalapril in PARADIGM-HF trial, and its initiation during hospitalization for acute HF or early after discharge can now be considered. More recently, new therapeutic pathways have been developed. In the DAPA-HF and EMPEROR-Reduced trials, dapagliflozin and empagliflozin reduced the risk of the primary composite endpoint, compared with placebo [hazard ratio (HR) 0.74; 95% confidence interval (CI) 0.65-0.85; P < 0.001 and HR 0.75; 95% CI 0.65-0.86; P < 0.001, respectively]. Second, vericiguat, an oral soluble guanylate cyclase stimulator, reduced the composite endpoint of cardiovascular death or HF hospitalization vs. placebo (HR 0.90; 95% CI 0.82-0.98; P = 0.02). On the other hand, both the diagnosis and treatment of HF with preserved ejection fraction, as well as management of advanced HF and acute HF, remain challenging. A better phenotyping of patients with HF would be helpful for prognostic stratification and treatment selection. Further aspects, such as the use of devices, treatment of arrhythmias, and percutaneous treatment of valvular heart disease in patients with HF, are also discussed and reviewed in this article.

Oxygen uptake efficiency slope: a reliable surrogate parameter for exercise capacity in healthy and cardiac children?

OBJECTIVES

Cardiopulmonary exercise test (CPET) provides accurate evaluation of physical capacity and disease severity in children with congenital heart disease (CHD). However, full participation to obtain optimal measure of VO_2max may be difficult. As an alternative, the oxygen uptake efficiency slope (OUES) is a reproducible and reliable parameter measured during CPET, which does not require a maximal exercise to be interpretable. This study aimed to evaluate the OUES of a large cohort of children with CHD, in comparison with healthy controls. We also intended to identify, in this specific population, the clinical and CPET variables associated with the OUES.

METHODS

This cross-sectional study was carried out between November 2010 and September 2015 in two tertiary care paediatric and congenital cardiology centres.

RESULTS

709 children were included (407 CHD and 302 healthy controls). The association of clinical characteristics with weight-normalised OUES (OUES_kg) was studied using a multivariable analysis. The mean OUES_kg was significantly lower in CHD than in healthy controls (38.6±8.5 and 43.9±8.5; p<0.001, respectively), especially in the most severe CHD. The OUES_kg correlated with VO_2max (r=0.85, p<0.001), with cut-off values for normal exercise capacity of 38.4 in boys and 31.0 in girls. The decrease of OUES_kg was associated with increased age, increased Body Mass Index, number of cardiac catheter or surgical procedures, female gender and decreased forced vital capacity (Z-score).

CONCLUSION

The OUES is significantly impaired in children with CHD and strongly correlates with VO_2max. The OUES has the same clinical determinants as VO_2max and therefore may be of interest in submaximal exercise.

TRIAL REGISTRATION NUMBER

NCT01202916.

Beta-blockers in heart failure prognosis: Lessons learned by MECKI Score Group papers

Heart failure is a complex syndrome affecting several organs including kidney, lungs, liver, brain muscles and sympathetic system. Each of these organs might contribute to its severity and prognosis. The prognosis assessment is critical for a correct heart failure management. It has already been demonstrated that a single parameter is weaker for prognosis than different parameters combined. The Metabolic Exercise test data combined with Cardiac and Kidney Indexes (MECKI) score has been built and validated for heart failure with reduced ejection fraction (HFrEF) patients by considering cardiopulmonary exercise test data combined with clinical, laboratory and echocardiographic measurements. The betablockers treatment is a milestone in the HFrEF management. In the MECKI score database, the association of betablockers treatment with outcome has been investigated in different settings.

Future developments in the MECKI score initiative

The Metabolic Exercise combined with Cardiac and Kidney Indexes [MECKI) score is a validated prognostic score for heart failure with reduced ejection fraction which combines commonly available clinical and metabolic parameters with two cardiopulmonary exercise test derived prognostic measurements. It has been validated to predict prognosis and to aid clinical decision making and it has been shown to be superior in predicting mortality compared with other commonly used prognostic scores for heart failure. In the future it would be valuable to establish whether the score holds true also in other settings, and in particular in under-represented groups – the elderly, women, and people of different ethnic backgrounds – and in other heart failure syndromes. In future it may be extended to assess its value in the presence of a range of co-morbidities such as chronic obstructive pulmonary disease, pulmonary hypertension and frailty and cachexia as well as in other conditions such as hypertrophic cardiomyopathy, amyloid, asymptomatic left ventricular dysfunction and hypertension. It may also be a candidate end-point for adaptive trials designed to prove an improvement in the MECKI score as an approvable interim end-point whilst larger mortality and morbidity trials are still underway.