peak/THV ratio in heart failure patients and control subjects. VO2peak/THV ratio in heart failure patients compared to healthy volunteers and different groups of athletes. The VO2peak/THV ratio was significantly lower in the heart failure patients compared to the control groups (A). This relationship remained unchanged after normalizing the results to hemoglobin levels (B). The solid line represents the mean value. ** p < 0.01 and *** p < 0.001 compared to healthy volunteers.