RBP-4 levels were significantly higher in HF patients compared to controls (46.66 ± 12.38 μg/mL vs. 40.71 ± 7.28 μg/mL, p < 0.001) and increased with worsening cardiac function, as indicated by higher New York Heart Association class, and reduced LVEF. This evidence concerns the gene RBP4 and hydrops fetalis.