LCZ696, a combination of the Ang II receptor inhibitor valsartan and the neprilysin inhibitor sacubitril, augmented active natriuretic peptides, resulting in an increase in cGMP in patients with HFpEF in the PARAMOUNT trial (540) and the PARAGON-HF trial (NCT01920711), offering opportunities for combined treatment with PDE9A inhibitors for HFpEF (123). Here, PDE9A is linked to hydrops fetalis.