TRED-HF was a pilot, open-label RCT of 51 patients with previous HFrEF secondary to dilated cardiomyopathy and current HFimpEF (defined as NYHA class 1; LVEF ≥ 50%; N-terminal prohormone of brain natriuretic peptide [NT-proBNP] < 250 ng/L) receiving at least one HFrEF medication. Here, NPPB is linked to hydrops fetalis.