Low GFR, low LVEF, cardiac troponin I levels and both spironolactone use and its dose were independent predictors of NT-proBNP levels (Table S.4, Model 1 and 2, Additional file 1), after adjustment for baseline clinical characteristics, other markers of HF severity and cardiovascular drugs with possible impact on NT-proBNP levels. This evidence concerns the gene NPPB and hydrops fetalis.