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.