The strongest correlations with CPXT parameters were found for miR-208b levels, which had a positive correlation with maximal oxygen uptake (peakVO2) (r = 0.671, P < 0.001), exercise duration (r = 0.445, P = 0.001), and minute ventilation-carbon dioxide production relationship (VE/VCO2) (r = 0.437, P = 0.001) in the HFpEF group.