NPPB and hydrops fetalis: The phase II SOCRATES-PRESERVED was a randomized, double-blind, placebo-controlled, dose-finding clinical trial in 477 patients with symptomatic chronic HF (NYHA functional classes II–IV) with preserved LVEF (defined as LVEF ≥ 45%) and a recent episode of worsening HF within 4 weeks, which required hospitalization or IV outpatient’s diuretic treatment, together with an elevation in natriuretic peptide levels at randomization (BNP ≥ 100 pg/mL or NT-proBNP levels ≥ 300 pg/mL if in sinus rhythm; BNP ≥ 200 pg/mL or NTproBNP ≥ 600 pg/mL if in atrial fibrillation) [26,30].