Physiological and psychological outcomes of high intensity interval training in patients with heart failure compared to moderate continuous training and usual care: A systematic review with meta analysis

Background: An important component of secondary prevention of CVD (including HF) is comprehensive cardiac rehab, including exercise. Novel, individualised approaches are needed to increase uptake and adherence to exercise programmes, one area offering potential is HIIT. HIIT has been shown to be both safe and effective for improving cardiovascular fitness in both coronary artery disease and HF patients. Objectives: To provide a current and up to date evaluation of the physiological and psychological outcomes of HIIT in patients with HF compared to MCT and UC. Secondly to perform sub-group analyses comparing short and long HIIT protocols. Methods: A systematic review and meta-analysis of randomised controlled trials was undertaken. Medline, Embase, Scopus, CINAHL and SportDISCUS were searched up to July 2022. Trials were included if they carried out a HIIT intervention (defined at intensity ≥ 80% peak HR or ≥ 80% VO2_peak) in HF patients (HFpEF or HFrEF) for at least 6 weeks. Comparator group was UC or MCT. Results: HIIT was shown to be superior to MCT and UC for improving VO_2peak (HIIT mean improvement 3.1 mL.kg⁻¹min⁻¹). HITT was superior to MCT and UC for improving LVEF (HIIT mean improvement 5.7%). HIIT was superior to MCT and UC for improving HRQoL, using the MLHFQ (HIIT mean point change of -12.8). Subgroup analysis showed no difference between long and short HIIT. Conclusion: HIIT improves VO_2peak, LVEF and HRQoL in patients with HF, the improvements seen in VO_2peak and LVEF are superior in HIIT compared to MCT and UC.