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

Effects of exercise training on cardiac output in subjects with heart failure with preserved ejection fraction (HFpEF) - a protocol for a systematic review and meta-analysis

BACKGROUND

Patients with heart failure with preserved ejection fraction (HFpEF) commonly experience exercise intolerance, resulting in reduced cardiorespiratory fitness. This is characterised by a decreased maximal oxygen uptake (V̇O2peak), which is determined by the product of cardiac output (CO) and arteriovenous oxygen difference (a-vDO2). While exercise training has been shown to improve V̇O2peak in HFpEF patients, the effects on CO remain unclear. The aim of this study is to systematically review and analyse the current evidence on the effects of supervised exercise training on CO in patients with HFpEF.

METHODS

We will systematically search for literature describing the effects of supervised exercise training on CO in patients with HFpEF. All eligible studies published before 30 June 2023 in the following electronic databases will be included: MEDLINE (Ovid), Embase (Ovid), SPORTDiscus (EBSCOhost), and CENTRAL (Cochrane Library). Effect sizes will be extracted for CO before and after a supervised exercise training intervention at rest and maximal exercise. Mass of heterogeneity (I2) will be calculated, and either fixed-effect models or random-effect models will be used for meta-analysis. To detect a potential publication bias, funnel plot analyses will be performed.

DISCUSSION

While several studies have reported a positive effect of supervised exercise training on cardiorespiratory fitness, attempts to assess the underlying determinants of V̇O2peak, CO, and a-vDO2 are much scarcer, especially in patients with HFpEF. From a physiological perspective, measuring CO before and after supervised exercise training seems to be a reasonable way to accurately operationalise a potential improvement in cardiac function.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022361485.

Supervised exercise training in heart failure with preserved ejection fraction: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) represents a prevalent and increasingly common condition. Recognized for its high incidence, there is a growing interest in exploring effective interventions, with exercise emerging as a critical component in the rehabilitation of HFpEF patients. We aim to update evidence on the impact of supervised exercise training on exercise capacity, diastolic function, arterial stiffness, and health-related quality of life (QoL) of individuals diagnosed with HFpEF.

METHODS

We systematically reviewed the literature, searching from inception to December 2023, utilizing databases such as MEDLINE (via PubMed), Google Scholar, the Cochrane Library, ClinicalTrials.gov, and the ScienceDirect portal. Statistical analyses utilized RevMan 5.4 with a random-effects model. Outcomes were presented as the weighted mean difference (WMD) alongside corresponding 95 % confidence intervals (CI), and heterogeneity was assessed using the I2 test.

RESULTS

Our final analysis included 7 randomized controlled trials (RCTs) of 346 participants, with an exercise follow-up duration of 12 to 48 weeks. In our pooled analysis, diastolic function, measured by E/A (WMD 0.01, 95 % CI: -0.04 to 0.05, p = 0.79; I2 = 0 %) and E/e' (WMD 0.87, 95 % CI: -11.09 to 12.83, p = 0.89; I2 = 69 %), showed no significant change post-exercise training. However, exercise capacity, measured by peak V̇o2 significantly improved (WMD 2.57, 95 % CI: 1.38 to 3.75, p < 0.0001; I2= 14 %). The QoL assessed by the Minnesota Living with Heart Failure (MLWHF) score remained unchanged (WMD -3.12, 95 % CI: -8.73 to 2.50, p = 0.28; I2 = 0 %), but the SF-36 physical functioning scale indicated significant improvement (WMD 9.84, 95 % CI: 2.94 to 16.73, p < 0.005; I2 = 0 %). Arterial stiffness and vascular function remained unaffected, as evidenced by arterial elastance (WMD -0.13, 95 % CI: -0.36 to 0.10, p = 0.26; I2 = 0 %) and total arterial compliance (WMD 0.12, 95 % CI: -0.26 to 0.49, p = 0.54; I2 = 0 %).

CONCLUSION

Exercise training is safe and significantly enhances exercise capacity and QoL in HFpEF, with no significant impact on diastolic function, arterial stiffness, or vascular function.

Exercise-based cardiac rehabilitation for adults with heart failure

BACKGROUND

People with heart failure experience substantial disease burden that includes low exercise tolerance, poor health-related quality of life (HRQoL), increased risk of mortality and hospital admission, and high healthcare costs. The previous 2018 Cochrane review reported that exercise-based cardiac rehabilitation (ExCR) compared to no exercise control shows improvement in HRQoL and hospital admission amongst people with heart failure, as well as possible reduction in mortality over the longer term, and that these reductions appear to be consistent across patient and programme characteristics. Limitations noted by the authors of this previous Cochrane review include the following: (1) most trials were undertaken in patients with heart failure with reduced (< 45%) ejection fraction (HFrEF), and women, older people, and those with heart failure with preserved (≥ 45%) ejection fraction (HFpEF) were under-represented; and (2) most trials were undertaken in a hospital or centre-based setting.

OBJECTIVES

To assess the effects of ExCR on mortality, hospital admission, and health-related quality of life of adults with heart failure.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, PsycINFO and Web of Science without language restriction on 13 December 2021. We also checked the bibliographies of included studies, identified relevant systematic reviews, and two clinical trials registers.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared ExCR interventions (either exercise only or exercise as part of a comprehensive cardiac rehabilitation) with a follow-up of six months or longer versus a no-exercise control (e.g. usual medical care). The study population comprised adults (≥ 18 years) with heart failure - either HFrEF or HFpEF.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were all-cause mortality, mortality due to heart failure, all-cause hospital admissions, heart failure-related hospital admissions, and HRQoL. Secondary outcomes were costs and cost-effectiveness. We used GRADE to assess the certainty of the evidence.

MAIN RESULTS

We included 60 trials (8728 participants) with a median of six months' follow-up. For this latest update, we identified 16 new trials (2945 new participants), in addition to the previously identified 44 trials (5783 existing participants). Although the existing evidence base predominantly includes patients with HFrEF, with New York Heart Association (NYHA) classes II and III receiving centre-based ExCR programmes, a growing body of trials includes patients with HFpEF with ExCR undertaken in a home-based setting. All included trials employed a usual care comparator with a formal no-exercise intervention as well as a wide range of active comparators, such as education, psychological intervention, or medical management. The overall risk of bias in the included trials was low or unclear, and we mostly downgraded the certainty of evidence of outcomes upon GRADE assessment. There was no evidence of a difference in the short term (up to 12 months' follow-up) in the pooled risk of all-cause mortality when comparing ExCR versus usual care (risk ratio (RR) 0.93, 95% confidence interval (CI) 0.71 to 1.21; absolute effects 5.0% versus 5.8%; 34 trials, 36 comparisons, 3941 participants; low-certainty evidence). Only a few trials reported information on whether participants died due to heart failure. Participation in ExCR versus usual care likely reduced the risk of all-cause hospital admissions (RR 0.69, 95% CI 0.56 to 0.86; absolute effects 15.9% versus 23.8%; 23 trials, 24 comparisons, 2283 participants; moderate-certainty evidence) and heart failure-related hospital admissions (RR 0.82, 95% CI 0.49 to 1.35; absolute effects 5.6% versus 6.4%; 10 trials; 10 comparisons, 911 participants; moderate-certainty evidence) in the short term. Participation in ExCR likely improved short-term HRQoL as measured by the Minnesota Living with Heart Failure (MLWHF) questionnaire (lower scores indicate better HRQoL and a difference of 5 points or more indicates clinical importance; mean difference (MD) -7.39 points, 95% CI -10.30 to -4.77; 21 trials, 22 comparisons, 2699 participants; moderate-certainty evidence). When pooling HRQoL data measured by any questionnaire/scale, we found that ExCR may improve HRQoL in the short term, but the evidence is very uncertain (33 trials, 37 comparisons, 4769 participants; standardised mean difference (SMD) -0.52, 95% CI -0.70 to -0.34; very-low certainty evidence). ExCR effects appeared to be consistent across different models of ExCR delivery: centre- versus home-based, exercise dose, exercise only versus comprehensive programmes, and aerobic training alone versus aerobic plus resistance programmes.

AUTHORS' CONCLUSIONS

This updated Cochrane review provides additional randomised evidence (16 trials) to support the conclusions of the previous 2018 version of the review. Compared to no exercise control, whilst there was no evidence of a difference in all-cause mortality in people with heart failure, ExCR participation likely reduces the risk of all-cause hospital admissions and heart failure-related hospital admissions, and may result in important improvements in HRQoL. Importantly, this updated review provides additional evidence supporting the use of alternative modes of ExCR delivery, including home-based and digitally-supported programmes. Future ExCR trials need to focus on the recruitment of traditionally less represented heart failure patient groups including older patients, women, and those with HFpEF.

High-Intensity Interval Training Versus Moderate Continuous Training in Patients With Heart Failure With Preserved Ejection Fraction: A Systematic Review and Meta-analysis

High-intensity interval training (HIIT) is a novel training approach that improves cardiopulmonary fitness and functional capacity in numerous chronic conditions, however its impact in patients with heart failure (HF) with preserved ejection fraction (HFpEF) is uncertain. We evaluated data from prior studies reporting the effects of HIIT versus moderate continuous training (MCT), on cardiopulmonary exercise outcomes in patients with HFpEF. PubMed and SCOPUS were queried from inception till February 1st, 2022 for all randomized controlled trials (RCT) comparing the effect of HIIT versus MCT in patients with HFpEF on peak oxygen consumption (peak VO₂), left atrial volume index (LAVI), respiratory exchange ratio (RER), and ventilatory efficiency (VE/CO₂ slope). A random-effects model was applied, and the weighted mean difference (WMD) of each outcome was reported with 95% confidence intervals (CI). Three RCTs (total N = 150 patients with HFpEF), with a follow-up of 4 to 52 weeks were included in our analysis. Our pooled analysis demonstrated that HIIT significantly improved peak VO₂ (WMD = 1.46 mL/kg/min (0.88, 2.05); P < 0.00001; I² = 0%), as compared to MCT. However, no statistically significant change was demonstrated for LAVI (WMD = -1.71 mL/m² (-5.58, 2.17); P = 0.39; I² = 22%), RER (WMD = -0.10 (-0.32, 0.12); P = 0.38; I² = 0%), and VE/CO₂ slope (WMD = 0.62 (-1.99, 3.24); P = 0.64; I² = 67%) in patients with HFpEF. Across current RCT data, HIIT, compared to MCT, had a significant impact on improving peak VO₂. Conversely, there was no significant change in LAVI, RER, and VE/CO₂ slope between HFpEF patients undertaking HIIT as opposed to MCT.