NPPB and hydrops fetalis: The Guiding Evidence-Based Therapy Using Biomarker-Intensified Treatment in Heart Failure (GUIDE-IT) trial was a randomized controlled trial (RCT) designed to evaluate the efficacy of an N-terminal pro–B type natriuretic peptide (NT-proBNP)–guided treatment plan in patients with clinical heart failure (HF) and a reduced left ventricular ejection fraction below 40%.1