In patients with HF with reduced EF, PDE5 inhibition therapy with sildenafil [144] or udenafil [145] was accompanied by a decrease in LV filling pressure (early mitral inflow to mitral annulus relaxation velocities (E/e’) ratio) along with a reverse remodeling of LA volume index, indicating LV diastolic function improvement. Here, PDE5A is linked to hydrops fetalis.