PDE4D and familial dilated cardiomyopathy: Taken together, selective inhibition of PDE4D could improve both diastolic and systolic heart function of DCM mice by restoring E–C coupling of myocytes and leads to notable alleviation in the pathomorphological changes of the myocardium as well, indicating that the PDE4D inhibitor may be superior to PDE4 inhibition in treating HFD-fed induce DCM.