NPPB and hydrops fetalis: The aim of this study was to compare biomarkers associated with poor clinical outcomes, that is, plasma brain natriuretic peptide (BNP), N-terminal-pro B-type natriuretic peptide (NT-proBNP), and C-reactive protein (CRP) in patients with HF and frailty vs. patients with HF without frailty.<h4>Methods</h4>From inception until July 2023, PubMed, Scopus, Web of Science, and Cochrane Library a systematic literature search was conducted.