Including CysC in the MAGGIC risk score-based model provided additional prognostic value for all subjects, even with N-terminal pro-brain natriuretic peptide (NT-proBNP) levels added.<h4>Conclusions</h4>CysC is an independent risk factor for adverse outcomes in HF patients across EF spectrum with normal to mild renal insufficiency. Here, NPPB is linked to hydrops fetalis.