Cardiopulmonary Exercise Testing in Patients with Heart Failure with Specific Comorbidities

Non-Invasive Cardiac Output Measurement Using Inert Gas Rebreathing Method during Cardiopulmonary Exercise Testing-A Systematic Review

BACKGROUND

The use of inert gas rebreathing for the non-invasive cardiac output measurement has produced measurements comparable to those obtained by various other methods. However, there are no guidelines for the inert gas rebreathing method during a cardiopulmonary exercise test (CPET). In addition, there is also a lack of specific standards for assessing the non-invasive measurement of cardiac output during CPET, both for healthy patients and those suffering from diseases and conditions.

AIM

This systematic review aims to describe the use of IGR for a non-invasive assessment of cardiac output during cardiopulmonary exercise testing and, based on the information extracted, to identify a proposed CPET report that includes an assessment of the cardiac output using the IGR method.

METHODS

This systematic review was conducted by PRISMA (Preferred Reporting Items for Systematic Reviews and Meta Analyses) guidelines. PubMed, Web of Science, Scopus, and Cochrane Library databases were searched from inception until 29 December 2022. The primary search returned 261 articles, of which 47 studies met the inclusion criteria for this review.

RESULTS AND CONCLUSIONS

This systematic review provides a comprehensive description of protocols, indications, technical details, and proposed reporting standards for a non-invasive cardiac output assessment using IGR during CPET. It highlights the need for standardized approaches to CPET and identifies gaps in the literature. The review critically analyzes the strengths and limitations of the studies included and offers recommendations for future research by proposing a combined report from CPET-IGR along with its clinical application.

Predictors of lower exercise capacity in patients with cancer

Maintaining cancer patients' exercise capacity and therefore patients' ability to live a self-determined life is of huge importance, but little is known about major determinants. We sought to identify determinants of exercise capacity in patients with a broad spectrum of cancer types, who were already receiving cancer treatment or about to commence such therapy. Exercise capacity was assessed in 253 consecutive patients mostly suffering from advanced cancer using the 6-min walk test (6-MWT). All patients underwent echocardiography, physical examination, resting electrocardiogram, hand grip strength (HGS) measurement, and laboratory assessments. Patients were divided into two groups according to the median distance in the 6-MWT (459 m). Patients with lower exercise capacity were older, had significantly lower HGS and haemoglobin and higher values of high sensitive (hs) Troponin T and NT-proBNP (all p < 0.05). Whilst the co-morbidity burden was significantly higher in this group, no differences were detected for sex, body mass index, tumor type, or cachexia (all p > 0.2). Using multivariable logistic regression, we found that the presence of anaemia (odds ratio (OR) 6.172, 95% confidence interval (CI) 1.401-27.201, p = 0.016) as well as an increase in hs Troponin T (OR 3.077, 95% CI 1.202-5.301, p = 0.019) remained independent predictors of impaired exercise capacity. Increasing HGS was associated with a reduced risk of a lower exercise capacity (OR 0.896, 95% CI 0.813-0.987, p = 0.026). Screening patients for elevated hs troponin levels as well as reduced HGS may help to identify patients at risk of lower exercise capacity during cancer treatment.

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.

Understanding Obesity-Related High Output Heart Failure and Its Implications

Morbid obesity remains most common cause of high output failure. The prevalence of the obesity is growing when two-thirds of American adults already are overweight or obese. Obesity is the risk factor for heart disease and eventually leads to heart failure. High output heart failure is common in obese patients and is characterized by high cardiac output, decreased systemic vascular resistance, and increased oxygen consumption. It often occurs in patients with chronic severe anemia, hyperthyroidism, pregnancy, arterial-venous fistulas, and liver disease. However, the pathogenesis of obesity-related high output heart failure is not fully understood. The clinical management of obesity-related high output heart failure follows conventional heart failure regimens due to lack of specific clinical recommendations. This article reviews the possible pathophysiological mechanisms and causes that contribute to obesity-related high output heart failure. This review also focuses on the implications for clinical practice and future research involved with omics technologies to explore possible molecular pathways associated with obesity-related high output heart failure.

Effects of hybrid comprehensive telerehabilitation on cardiopulmonary capacity in heart failure patients depending on diabetes mellitus: subanalysis of the TELEREH-HF randomized clinical trial

BACKGROUND

Type 2 diabetes mellitus (DM) is one of the most common comorbidities among patients with heart failure (HF) with reduced ejection fraction (HFrEF). There are limited data regarding efficacy of hybrid comprehensive telerehabilitation (HCTR) on cardiopulmonary exercise capacity in patients with HFrEF with versus those without diabetes.

AIM

The aim of the present study was to analyze effects of 9-week HCTR in comparison to usual care on parameters of cardiopulmonary exercise capacity in HF patients according to history of DM.

METHODS

Clinically stable HF patients with left ventricular ejection fraction [LVEF] < 40% after a hospitalization due to worsening HF within past 6 months were enrolled in the TELEREH-HF (The TELEREHabilitation in Heart Failure Patients) trial and randomized to the HCTR or usual care (UC). Cardiopulmonary exercise tests (CPET) were performed on treadmill with an incremental workload according to the ramp protocol.

RESULTS

CPET was performed in 385 patients assigned to HCTR group: 129 (33.5%) had DM (HCTR-DM group) and 256 patients (66.5%) did not have DM (HCTR-nonDM group). Among 397 patients assigned to UC group who had CPET: 137 (34.5%) had DM (UC-DM group) and 260 patients (65.5%) did not have DM (UC-nonDM group). Among DM patients, differences in cardiopulmonary parameters from baseline to 9 weeks remained similar among HCTR and UC patients. In contrast, among patients without DM, HCTR was associated with greater 9-week changes than UC in exercise time, which resulted in a statistically significant interaction between patients with and without DM: difference in changes in exercise time between HCTR versus UC was 12.0 s [95% CI - 15.1, 39.1 s] in DM and 43.1 s [95% CI 24.0, 63.0 s] in non-DM, interaction p-value = 0.016. Furthermore, statistically significant differences in the effect of HCTR versus UC between DM and non-DM were observed in ventilation at rest: - 0.34 l/min [95% CI - 1.60, 0.91 l/min] in DM and 0.83 l/min [95% CI - 0.06, 1.73 l/min] in non-DM, interaction p value = 0.0496 and in VE/VCO2 slope: 1.52 [95% CI - 1.55, 4.59] for DM vs. - 1.44 [95% CI - 3.64, 0.77] for non-DM, interaction p value = 0.044.

CONCLUSIONS

The benefits of hybrid comprehensive telerehabilitation versus usual care on the improvement of physical performance, ventilatory profile and gas exchange parameters were more pronounced in patients with HFrEF without DM as compared to patients with DM.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02523560. Registered 3rd August 2015. https://clinicaltrials.gov/ct2/show/NCT02523560?term=NCT02523560&draw=2&rank=1 . Other Study ID Numbers: STRATEGME1/233547/13/NCBR/2015.

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.

Aerobic exercise prescription in heart failure patients with cardiac resynchronization therapy

Exercise for heart failure patients had been shown to be beneficial in improving functional status, and was reviewed to be safe. In cases of advanced heart failure, Cardiac Resynchronization Therapy (CRT) is a promising medical option before being a heart transplant candidate. CRT itself is a biventricular pacing device, which could detect electrical aberrance in the failing heart and provide a suitable response. Studies have shown that exercise has clear benefits toward improving an overall exercise capacity of the patients. Despite its impacts, these randomized clinical trials have varying exercise regime, and until now there has not been a standardized exercise prescription for this group of patients. The nature of CRT as a pacemaker, sometimes with defibrillator, being attached to a heart failure patient, each has its own potential exercise hazards. Therefore, providing detailed exercise prescription in adjusting to the medical condition is very essential in the field of physical medicine and rehabilitation. Being classified as a high-risk patient group, exercise challenges for the complex heart failure with CRT patients will then be discussed in this literature review, with a general aim to provide a safe, effective, and targeted exercise regime.

Definition and assessment of frailty in older patients: the surgical, anaesthesiological and oncological perspective

The number of oncology, surgery and anaesthesia procedures in older patients has greatly increased in recent years due to ageing populations. Older patients are typically characterised by physical changes such as comorbidities, decline in physiological activities and cognitive impairment. All these factors, together with polypharmacological therapies, may substantially impact perioperative outcome, quality of recovery and, more in general, quality of life. A comprehensive multidisciplinary approach to perioperative care is thus needed. The assessment of frailty has a central role in the pre-operative evaluation of older patients and, with a multidisciplinary approach. The best surgical procedures and oncologic therapies can be accurately discussed in the pre- and post-operative periods. All clinicians involved in this scenario should be proactive in multidisciplinary care to achieve better outcomes.

Effect of Physical Exercise Training in Patients With Chagas Heart Disease (from the PEACH STUDY)

Chagas heart disease (HD) is a chronic fibrosing myocarditis with high mortality. The PEACH study aimed to evaluate if exercise training can improve the functional capacity of Chagas HD patients with left ventricular dysfunction and/or heart failure. The PEACH study was a single center, parallel-group, clinical trial that randomized 30 clinical stable Chagas HD patients with left ventricular ejection fraction <45% or heart failure symptoms to either supervised exercise training 3 times/week for 6 months or a control group. Both groups had the same monthly pharmaceutical and nutritional counseling and usual care. Primary end point was functional capacity assessed by peak exercise oxygen consumption (peak VO₂) obtained by cardiopulmonary exercise test. Secondary end points included other cardiopulmonary exercise test variables, cardiac function by echocardiography, body composition, muscle respiratory strength, and metabolic biomarkers. Peak VO₂ increased among patients in exercise group from 17.60 ± 4.65 mlO₂ kg^-1 min^-1 to 19.40 ± 5.51 mlO₂ kg^-1 min^-1 while decreased in controls from 15.40 ± 6.30 mlO₂ kg^-1 min^-1 to 12.96 ± 4.50 mlO₂ kg^-1 min^-1, resulting in significant difference in change in peak VO₂ between groups after 6 months (β = +4.6, p = 0.004). There were significant differences between groups in changes in anaerobic threshold (β = 3.7, p = 0.05), peak oxygen pulse (β = +2.7, p = 0.032) and maximum minute ventilation (β = +13.9, p < 0.0001) after 6 months of intervention. In conclusion, exercise training improved functional capacity of chronic Chagas HD patients with left ventricular dysfunction and/or heart failure.

Effects of bi-level positive airway pressure on ventilatory and perceptual responses to exercise in comorbid heart failure-COPD

This study tested the hypothesis that, by increasing the volume available for tidal expansion (inspiratory capacity, IC), bi-level positive airway pressure (BiPAP™) would lead to greater beneficial effects on dyspnea and exercise intolerance in comorbid heart failure (HF)-chronic obstructive pulmonary disease (COPD) than HF alone. Ten patients with HF and 9 with HF-COPD (ejection fraction = 30 ± 6% and 35 ± 7%; FEV₁ = 83 ± 12% and 65 ± 15% predicted, respectively) performed a discontinuous exercise protocol under sham ventilation or BiPAP™. Time to intolerance increased with BiPAP™ only in HF-COPD (p < 0.05). BiPAP™ led to higher tidal volume and lower duty cycle with longer expiratory time (p < 0.05). Of note, BiPAP™ improved IC (by ∼0.5 l) across exercise intensities only in HF-COPD. These beneficial consequences were associated with lower dyspnea scores at higher levels of ventilation (p < 0.05). By improving the qualitative" (breathing pattern and operational lung volumes) and sensory (dyspnea) features of exertional ventilation, BiPAP™ might allow higher exercise intensities to be sustained for longer during cardiopulmonary rehabilitation in HF-COPD.

Current challenges in managing comorbid heart failure and COPD

INTRODUCTION

Heart failure (HF) with reduced ejection fraction and chronic obstructive pulmonary disease (COPD) frequently coexist, particularly in the elderly. Given their rising prevalence and the contemporary trend to longer life expectancy, overlapping HF-COPD will become a major cause of morbidity and mortality in the next decade. Areas covered: Drawing on current clinical and physiological constructs, the consequences of negative cardiopulmonary interactions on the interpretation of pulmonary function and cardiopulmonary exercise tests in HF-COPD are discussed. Although those interactions may create challenges for the diagnosis and assessment of disease stability, they provide a valuable conceptual framework to rationalize HF-COPD treatment. The impact of COPD or HF on the pharmacological treatment of HF or COPD, respectively, is then comprehensively discussed. Authors finalize by outlining how the non-pharmacological treatment (i.e. rehabilitation and exercise reconditioning) can be tailored to the specific needs of patients with HF-COPD. Expert commentary: Randomized clinical trials testing the efficacy and safety of new medications for HF or COPD should include a sizeable fraction of patients with these coexistent pathologies. Multidisciplinary clinics involving cardiologists and respirologists trained in both diseases (with access to unified cardiorespiratory rehabilitation programs) are paramount to decrease the humanitarian and social burden of HF-COPD.

Low skeletal muscle mass is associated with low aerobic capacity and increased mortality risk in patients with coronary heart disease - a CARE CR study

BACKGROUND

In patients with chronic heart failure, there is a positive linear relationship between skeletal muscle mass (SMM) and peak oxygen consumption ( V ˙ O_2peak ); an independent predictor of all-cause mortality_. We investigated the association between SMM and V ˙ O_2peak in patients with coronary heart disease (CHD) without a diagnosis of heart failure.

METHODS

Male patients with CHD underwent maximal cardiopulmonary exercise testing and dual X-ray absorptiometry assessment. V ˙ O_2peak, the ventilatory anaerobic threshold and peak oxygen pulse were calculated. SMM was expressed as appendicular lean mass (lean mass in both arms and legs) and reported as skeletal muscle index (SMI; kg m^-2 ), and as a proportion of total body mass (appendicular skeletal mass [ASM%]). Low SMM was defined as a SMI <7·26 kg m^-2 , or ASM% <25·72%. Five-year all-cause mortality risk was calculated using the Calibre 5-year all-cause mortality risk score.

RESULTS

Sixty patients were assessed. Thirteen (21·7%) had low SMM. SMI and ASM% correlated positively with V ˙ O_2peak (r = 0·431 and 0·473, respectively; P<0·001 for both). SMI and ASM% predicted 16·3% and 12·9% of the variance in V ˙ O_2peak , respectively. SMI correlated most closely with peak oxygen pulse (r = 0·58; P<0·001). SMI predicted 40·3% of peak V ˙ O₂ /HR variance. ASM% was inversely associated with 5-year all-cause mortality risk (r = -0·365; P = 0·006).

CONCLUSION

Skeletal muscle mass was positively correlated with V ˙ O_2peak in patients with CHD. Peak oxygen pulse had the strongest association with SMM. Low ASM% was associated with a higher risk of all-cause mortality. The effects of exercise and nutritional strategies aimed at improving SMM and function in CHD patients should be investigated.