This observation is clearly in line with the increased oxidative stress and reduced NO level seen in the LV of our HFrEF rats, since comprehensive data support the concept of ROS-induced downregulation of the NO-soluble guanylyl cyclase (sGC)-cGMP-PKG signaling pathway leading to elevated diastolic stiffness in human HF [32]. Here, SGCB is linked to hydrops fetalis.