Exercise in Heart Failure—What Is the Optimal Dose to Improve Pathophysiology and Exercise Capacity?

Non-Pharmacological Interventions in Patients With Heart Failure With Reduced Ejection Fraction: A Systematic Review and Network Meta-analysis

OBJECTIVE

To determine the effectiveness of non-pharmacologic interventions and the additional benefits of their combination in patients with heart failure with reduced ejection fraction (HFrEF).

DATA SOURCES

We searched PubMed, Embase, and the Cochrane Clinical Trials Register from the date of database inception to April 22, 2023.

STUDY SELECTION

Randomized controlled trials involving non-pharmacologic interventions conducted in patients with HFrEF were included.

DATA EXTRACTION

Data were extracted by 2 independent reviewers based on a pre-tested data extraction form. The quality of evidence was assessed using the Cochrane Risk of Bias tool and the Grading of Recommendations Assessment, Development, and Evaluation method.

DATA SYNTHESIS

A total of 82 eligible studies (4574 participants) were included. We performed a random-effects model within a Bayesian framework to calculate weighted mean differences (WMDs) and 95% credibility intervals. High or moderate certainty evidence indicated that high-intensity aerobic interval training (HIAIT) was best on improving 6-minute walk distance (6MWD; 68.55 m [36.41, 100.47]) and left ventricular ejection fraction (6.28% [3.88, 8.77]), while high-intensity aerobic continuous training (HIACT) is best on improving peak oxygen consumption (Peak VO2; 3.48 mL/kg•min [2.84, 4.12]), quality of life (QOL; -17.26 [-29.99, -7.80]), resting heart rate (-8.20 bpm [-13.32, -3.05]), and N-terminal pro-B-type natriuretic peptide (-600.96 pg/mL [-902.93, -404.52]). Moderate certainty evidence supported the effectiveness of inspiratory muscle training to improve peak oxygen consumption and functional electrical stimulation to improve QOL. Moderate-intensity aerobic continuous training (MIACT) plus moderate-intensity resistance training (MIRT) had additional benefits in Peak VO2, 6MWD, and QOL. This review did not provide a comprehensive evaluation of adverse events.

CONCLUSIONS

Both HIAIT and HIACT are the most effective single non-pharmacologic interventions for HFrEF. MIACT plus MIRT had additional benefits in improving peak oxygen consumption, 6MWD, and QOL.

The Pathophysiology and New Advancements in the Pharmacologic and Exercise-Based Management of Heart Failure With Reduced Ejection Fraction: A Narrative Review

Heart failure with reduced ejection fraction (HFrEF) is a clinical syndrome whose management has significantly evolved based on the pathophysiology and disease process. It is widely prevalent, has a relatively high mortality rate, and is comparatively more common in men than women. In HFrEF, the series of maladaptive processes that occur lead to an inability of the muscle of the left ventricle to pump blood efficiently and effectively, causing cardiac dysfunction. The neurohormonal and hemodynamic adaptations play a significant role in the advancement of the disease and are critical to guiding the treatment and management of HFrEF. The first-line therapy, which includes loop diuretics, β-blockers, angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers, hydralazine/isosorbide-dinitrate, and mineralocorticoid receptor antagonists (MRAs), has been proven to provide symptomatic relief and decrease mortality and complications. The newly recommended drugs for guideline-based therapy, angiotensin receptor/neprilysin inhibitor (ARNI), sodium-glucose cotransporter 2 inhibitors, soluble guanylate cyclase, and myosin activators and modulators have also been shown to improve cardiac function, reverse cardiac remodeling, and reduce mortality rates. Recent studies have demonstrated that exercise-based therapy has resulted in an improved quality of life, exercise capacity, cardiac function, and decreased hospital readmission rates, but it has not had a considerable reduction in mortality rates. Combining multiple therapies alongside holistic advances such as exercise therapy may provide synergistic benefits, ultimately leading to improved outcomes for patients with HFrEF. Although first-line treatment, novel pharmacologic management, and exercise-based therapy have been shown to improve prognosis, the existing literature suggests a need for further studies evaluating the long-term effects of MRA and ARNI.

Effects of high intensity interval training versus moderate intensity continuous training on exercise capacity and quality of life in patients with heart failure: A systematic review and meta-analysis

INTRODUCTION AND AIMS

High intensity interval training (HIIT) is considered as an alternative exercise modality to moderate intensity continuous training (MICT) for heart failure (HF) patients. Yet a growing number of trials demonstrated inconsistent findings about the effectiveness of HIIT versus MICT until SMARTEX study and OptimEx-Clin study have made a consistent negative conclusion that HIIT was not superior to MICT. The aim of this study was to conduct a meta-analysis involving a subgroup analysis of total exercise time (TET) and disease categories of HF to investigate if TET could affect the superiority of HIIT when compared with MICT.

METHODS AND RESULTS

An electronic literature search of Pubmed, Embase, Cochrane Central Register of Controlled Trials and ClinicalTrials.gov was performed for this review. 16 studies of 661 patients were finally pooled into quantitative synthesis. The weighted mean difference (WMD) and standard mean difference (SMD) with 95% confidence interval (CI) were calculated for quantitative synthesis of outcomes. HIIT was superior to MICT in improving peak oxygen consumption (Peak VO2) (WMD: 1.68 ml · kg-1 · min-1 95% CI: 0.81 to 2.55 n = 661). The subgroup analysis of TET showed that HIIT was superior to MICT in improving Peak VO2 in "short time" subgroup (WMD: 1.61 ml · kg-1 · min-1 95% CI: 0.45 to 2.77 n = 166) and in "medium time" subgroup (WMD: 1.74 ml · kg-1 · min-1 95% CI: 0.53 to 2.95 n = 420), and that there was no significant difference between HIIT and MICT in improving Peak VO2 in "long time" subgroup (WMD: 0.62 ml · kg-1 · min-1 95% CI: -1.34 to 2.58 n = 75).

CONCLUSIONS

The superiority of HIIT to MICT in improving Peak VO2 arose in a short to medium length of TET whereas it was effaced by an increment of TET. This "paradox" of TET on HIIT versus MICT might be due to the increasing poor adherence to target exercise intensity over time.

TRIAL REGISTRATION

PROSPERO registration number: CRD42022375076.

Cardiovascular Disease and Exercise: From Molecular Mechanisms to Clinical Applications

Inactivity is a significant risk factor for cardiovascular disease. Exercise may greatly enhance the metabolism and function of the cardiovascular system, lower several risk factors, and prevent the development and treatment of cardiovascular disease while delivering easy, physical, and emotional enjoyment. Exercise regulates the cardiovascular system by reducing oxidative stress and chronic inflammation, regulating cardiovascular insulin sensitivity and the body's metabolism, promoting stem cell mobilization, strengthening autophagy and myocardial mitochondrial function, and enhancing cardiovascular damage resistance, among other effects. Appropriate exercise intervention has become an essential adjuvant therapy in clinical practice for treating and rehabilitating various cardiovascular diseases. However, the prescription of exercise for preventing and treating cardiovascular diseases, particularly the precise selection of individual exercise techniques and their volume, remains controversial. Using multiomics to explain further the molecular process underlying the positive effects of exercise on cardiovascular health will not only improve our understanding of the effects of exercise on health but also establish a scientific basis and supply new ideas for preventing and treating cardiovascular diseases by activating the endogenous protective mechanisms of the body and suggesting more specific exercise prescriptions for cardiovascular rehabilitation.

Impact of Different Training Modalities on Molecular Alterations in Skeletal Muscle of Patients With Heart Failure With Preserved Ejection Fraction: A Substudy of the OptimEx Trial

Background:

Exercise intolerance is a cardinal feature of heart failure with preserved ejection fraction and so far exercise training (ET) is the most effective treatment. Since the improvement in exercise capacity is only weakly associated with changes in diastolic function other mechanisms, like changes in the skeletal muscle, contribute to improvement in peak oxygen consumption. The aim of the present study was to analyze molecular changes in skeletal muscle of patients with heart failure with preserved ejection fraction performing different ET modalities.

Methods:

Skeletal muscle biopsies were taken at study begin and after 3 and 12 months from patients with heart failure with preserved ejection fraction randomized either into a control group (guideline based advice for ET), a high-intensity interval training group (HIIT) or a moderate continuous training group. The first 3 months of ET were supervised in-hospital followed by 9 months home-based ET. Protein and mRNA expression of atrophy-related proteins, enzyme activities of enzymes linked to energy metabolism and satellite cells (SCs) were quantified.

Results:

Exercise capacity improved 3 months after moderate continuous exercise training and HIIT. This beneficial effect was lost after 12 months. HIIT mainly improved markers of energy metabolism and the amount and function of SC, with minor changes in markers for muscle atrophy. Only slight changes were observed after moderate continuous exercise training. The molecular changes were no longer detectable after 12 months.

Conclusions:

Despite similar improvements in exercise capacity by HIIT and moderate continuous exercise training after 3 months, only HIIT altered proteins related to energy metabolism and amount/function of SC. These effects were lost after switching from in-hospital to at-home-based ET.

Registration:

URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02078947.

High-Intensity Interval Training for Heart Failure Patients With Preserved Ejection Fraction (HIT-HF)-Rational and Design of a Prospective, Randomized, Controlled Trial

Background: The pathophysiology of HF with preserved ejection fraction (HFpEF) has not yet been fully understood and HFpEF is often misdiagnosed. Remodeling and fibrosis stimulated by inflammation appear to be main factors for the progression of HFpEF. In contrast to patients with HF with reduced ejection fraction, medical treatment in HFpEF is limited to relieving HF symptoms. Since mortality in HFpEF patients remains unacceptably high with a 5-year survival rate of only 30%, new treatment strategies are urgently needed. Exercise seems to be a valid option. However, the optimal training regime still has to be elucidated. Therefore, the aim of the study is to investigate the effects of a high-intensity interval (HIT) training vs. a moderate continuous training (MCT) on exercise capacity and disease-specific mechanisms in a cohort of patients with HFpEF. Methods: The proposed study will be a prospective, randomized controlled trial in a primary care setting including 86 patients with stable HFpEF. Patients will undergo measurements of exercise capacity, disease-specific blood biomarkers, cardiac and arterial vessel structure and function, total hemoglobin mass, metabolic requirements, habitual physical activity, and quality of life (QoL) at baseline and follow-up. After the baseline visit, patients will be randomized to the intervention or control group. The intervention group (n = 43) will attend a supervised 12-week HIT on a bicycle ergometer combined with strength training. The control group (n = 43) will receive an isocaloric supervised MCT combined with strength training. After 12 weeks, study measurements will be repeated in all patients to quantify the effects of the intervention. In addition, telephone interviews will be performed at 6 months, 1, 2, and 3 years after the last visit to assess clinical outcomes and QoL. Discussion: We anticipate clinically significant changes in exercise capacity, expressed as VO_2peak, as well as in disease-specific mechanisms following HIT compared to MCT. Moreover, the study is expected to add important knowledge on the pathophysiology of HFpEF and the clinical benefits of a training intervention as a novel treatment strategy in HFpEF patients, which may help to improve both QoL and functional status in affected patients. Trial registration: ClinicalTrials.gov, identifier: NCT03184311, Registered 9 June 2017.

The importance of physical activity and cardiorespiratory fitness for patients with heart failure

The present review highlights current research on the importance of PA and fitness for patients with heart failure and recommendations with respect to heart failure phenotypes and special populations. Furthermore, the evidence for various exercise types and intensities/doses as an "exercise prescription", are discussed. The strong association between heart failure and traditional risk factors, physical inactivity and low fitness, underlines the importance of regular PA and exercise for prevention and treatment of heart failure. This is illustrated by cardiac stiffness which typically accelerates in middle-life and could be reversed by aerobic exercise. In patients with HFpEF, regular PA counteracts many of the changes observed, both metabolic and functional. Indeed, exercise-based cardiac rehabilitation has received a class 1A recommendation in current guidelines [1], in order to improve functional capacity, quality of life and lower the risk of rehospitalization. An individually tailored plan based on risk stratification, clinical assessment and cardiopulmonary exercise testing is encouraged before initiation of exercise training in patients with heart failure. In general, a combination of aerobic exercise and resistance training protocols is recommended (Table 1) [2], preferably throughout life. More studies are needed, regarding the role of PA and exercise in specific populations, such as frail patients with heart failure.

Exercise and sports after COVID-19-Guidance from a clinical perspective

SARS‐CoV‐2 infection has emerged as not only a pulmonary but also potentially multi‐organ disease, which may cause long‐term structural damage of different organ systems including the lung, heart, vasculature, brain, liver, kidney, or intestine. As a result, the current SARS‐CoV‐2/COVID‐19 pandemic will eventually yield substantially increased numbers of chronically diseased patients worldwide, particularly suffering from pulmonary fibrosis, post‐myocarditis, chronic heart failure, or chronic kidney disease. Exercise recommendations for rehabilitation are complex in these patients and should follow current guidelines including standards for pre‐exercise medical examinations and individually tailored exercise prescription. It is of utmost importance to start exercise training at an early stage after COVID‐19 infection, but at the same time paying attention to the physical barriers to ensure safe return to exercise. For exercise recommendations beyond rehabilitation programs particularly for leisure time and elite athletes, more precise advice is required including assessment of sports eligibility and specific return‐to‐sports exercise programs. Because of the current uncertainty of long‐term course of SARS‐CoV‐2 infection or COVID disease, long‐term follow‐up seems to be necessary.

Carvedilol and exercise combination therapy improves systolic but not diastolic function and reduces plasma osteopontin in Col4a3-/- Alport mice

There are currently no Food and Drug Administration-approved treatments for heart failure with preserved ejection fraction (HFpEF). Here we compared the effects of exercise with and without α/β-adrenergic blockade with carvedilol in Col4a3-/- Alport mice, a model of the phenogroup 3 subclass of HFpEF with underlying renal dysfunction. Alport mice were assigned to the following groups: no treatment control (n = 29), carvedilol (n = 11), voluntary exercise (n = 9), and combination carvedilol and exercise (n = 8). Cardiac function was assessed by echocardiography after 4-wk treatments. Running activity of Alport mice was similar to wild types at 1 mo of age but markedly reduced at 2 mo (1.3 ± 0.40 vs. 4.5 ± 1.02 km/day, P < 0.05). There was a nonsignificant trend for increased running activity at 2 mo by carvedilol in the combination treatment group. Combination treatments conferred increased body weight of Col4a3-/- mice (22.0 ± 1.18 vs. 17.8 ± 0.29 g in untreated mice, P < 0.01), suggesting improved physiology, and heart rates declined by similar increments in all carvedilol-treatment groups. The combination treatment improved systolic parameters; stroke volume (30.5 ± 1.99 vs. 17.8 ± 0.77 μL, P < 0.0001) as well as ejection fraction and global longitudinal strain compared with controls. Myocardial performance index was normalized by all interventions (P < 0.0001). Elevated osteopontin plasma levels in control Alport mice were significantly lowered only by combination treatment, and renal function of the Alport group assessed by urine albumin creatinine ratio was significantly improved by all treatments. The results support synergistic roles for exercise and carvedilol to augment cardiac systolic function of Alport mice with moderately improved renal functions but no change in diastole.NEW & NOTEWORTHY In an Alport mouse model of heart failure with preserved ejection fraction (HFpEF), exercise and carvedilol synergistically improved systolic function without affecting diastole. Carvedilol alone or in combination with exercise also improved kidney function. Molecular analyses indicate that the observed improvements in cardiorenal functions were mediated at least in part by effects on serum osteopontin and related inflammatory cytokine cascades. The work presents new potential therapeutic targets and approaches for HFpEF.

Age matters: differences in exercise-induced cardiovascular remodelling in young and middle aged healthy sedentary individuals

AIMS

Remodelling of the cardiovascular system (including heart and vasculature) is a dynamic process influenced by multiple physiological and pathological factors. We sought to understand whether remodelling in response to a stimulus, exercise training, altered with healthy ageing.

METHODS

A total of 237 untrained healthy male and female subjects volunteering for their first time marathon were recruited. At baseline and after 6 months of unsupervised training, race completers underwent tests including 1.5T cardiac magnetic resonance, brachial and non-invasive central blood pressure assessment. For analysis, runners were divided by age into under or over 35 years (U35, O35).

RESULTS

Injury and completion rates were similar among the groups; 138 runners (U35: n = 71, women 49%; O35: n = 67, women 51%) completed the race. On average, U35 were faster by 37 minutes (12%). Training induced a small increase in left ventricular mass in both groups (3 g/m2, P < 0.001), but U35 also increased ventricular cavity sizes (left ventricular end-diastolic volume (EDV)i +3%; left ventricular end-systolic volume (ESV)i +8%; right ventricular end-diastolic volume (EDV)i +4%; right ventricular end-systolic volume (ESV)i +5%; P < 0.01 for all). Systemic aortic compliance fell in the whole sample by 7% (P = 0.020) and, especially in O35, also systemic vascular resistance (-4% in the whole sample, P = 0.04) and blood pressure (systolic/diastolic, whole sample: brachial -4/-3 mmHg, central -4/-2 mmHg, all P < 0.001; O35: brachial -6/-3 mmHg, central -6/-4 mmHg, all P < 0.001).

CONCLUSION

Medium-term, unsupervised physical training in healthy sedentary individuals induces measurable remodelling of both heart and vasculature. This amount is age dependent, with predominant cardiac remodelling when younger and predominantly vascular remodelling when older.

Myocarditis in athletes: A clinical perspective

Myocarditis is an important cause of arrhythmias and sudden cardiac death (SCD) in both physically active individuals and athletes. Elite athletes seem to have an increased risk for viral infection and subsequent myocarditis due to increased exposure to pathogens (worldwide traveling/international competition) or impaired immune system (continuing training during infections/resuming training early thereafter, strenuous exercise training or competition, and exercising in extreme weather conditions). Initial clinical presentation is variable, but athletes characteristically express non-specific symptoms of fatigue, muscle soreness, increased heart rate at rest, as well as during exercise and reduced overall exercise capacity. Beyond resting electrocardiogram (ECG), cardiac biomarkers, echocardiography, and 24-hour Holter ECG, diagnostic work-up should include cardiac magnetic resonance imaging (CMR) assessing inflammation, oedema, and fibrosis by late gadolinium enhancement (LGE), respectively, as these measures are crucial for prognosis and sports eligibility. For patients with insufficient cardiac recovery, endomyocardial biopsy is recommended to clarify differential diagnoses and initiate specific treatment options. In uncomplicated cases with normal left ventricular function during acute phase and absent LGE, eligibility for sports can be attested to three months after clinical recovery. In those with persistent pathological findings, even after six months, the risk for SCD remains increased and resuming exercise beyond recreational activities can only be recommended individually based on course of disease, left ventricular function, arrhythmias, pattern of LGE in CMR, as well as intensity and volume of exercise performed during training and competition. For all athletes, follow-up examination should be performed yearly.

[Lifestyle intervention in the primary prevention of cardiovascular diseases]

Cardiovascular diseases are the leading cause of death worldwide. Adherence to a healthy lifestyle lifelong is capable of significantly reducing the cardiovascular risk by up to 70% and is therefore a key component in primary prevention of cardiovascular disease. According to the European and American guidelines lifestyle interventions include not smoking, daily physical activity of ≥150 min/week at moderate intensity or 75 min/week for higher intensity physical activity, a cardioprotective nutrition (high proportion of unsaturated fatty acids, low amounts of saturated fatty acids and low salt intake), normal body weight (body mass index 20-25 kg/m²), arterial blood pressure <140/90 mm Hg (optimum <130/80 mm Hg), low-density lipoprotein (LDL)-cholesterol target values depending on the cardiovascular risk and a normal glucose metabolism in type 2 diabetes mellitus with adjustment of a HbA1c to <7%. Lifestyle measures with weight reduction and intensification of physical activity can improve the cardiometabolic risk factors. In this way reduction of the systolic and diastolic blood pressures by approximately 10-15 mm Hg, reduction of HbA1c by approximately 1 % and reduction of triglycerides by ca. 30-40 % are possible. The LDL-cholesterol and lipoprotein(a) levels cannot be easily influenced. Beyond the recommendations for a cardioprotective lifestyle, additional pharmacological therapy may have to be added depending on the cardiovascular risk profile.

High-intensity interval training is effective and superior to moderate continuous training in patients with heart failure with preserved ejection fraction: A randomized clinical trial

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) is a prevalent syndrome, with exercise intolerance being one of its hallmarks, contributing to worse quality of life and mortality. High-intensity interval training is an emerging training option, but its efficacy in HFpEF patients is still unknown.

DESIGN

Single-blinded randomized clinical trial.

METHODS

Single-blinded randomized clinical trial with exercise training 3 days per week for 12 weeks. HFpEF patients were randomly assigned to high-intensity interval training or moderate continuous training. At baseline and after 12 week follow-up, patients underwent clinical assessment, echocardiography and cardiopulmonary exercise testing (CPET).

RESULTS

Mean age was 60 ± 9 years and 63% were women. Both groups (N = 19) showed improved peak oxygen consumption (VO₂), but high-intensity interval training patients (n = 10) had a significantly higher increase, of 22%, compared with 11% in the moderate continuous training (n = 9) individuals (3.5 (3.1 to 4.0) vs. 1.9 (1.2 to 2.5) mL·kg^-1·min^-1, p < 0.001). Ventilatory efficiency and other CPET measures, as well as quality of life score, increased equally in the two groups. Left ventricular diastolic function also improved with training, reflected by a significant reduction in E/e' ratio by echocardiography (-2.6 (-4.3 to -1.0) vs. -2.2 (-3.6 to -0.9) for high-intensity interval training and moderate continuous training, respectively; p < 0.01). There were no exercise-related adverse events.

CONCLUSIONS

This randomized clinical trial provided evidence that high-intensity interval training is a potential exercise modality for HFpEF patients, being more effective than moderate continuous training in improving peak VO₂. However, the two strategies were equally effective in improving ventilatory efficiency and other CPET parameters, quality of life score and diastolic function after 3 months of training.