SAA1 and hydrops fetalis: Similar to other studies which identified serum amyloid A1 (SAA1) as differentially abundant protein in human HF samples [8,20,21], we also demonstrated that SAA1 was perturbed in chronic HFpEF compared to HCM with a substantial fold change (log2FC = 7.82, FDR = 7.47 × 10−3).