Many studies have shown that pirfenidone can reduce production of TGF-β1 in vitro[20], [45] and in vivo[46]–[49], and one study in particular has demonstrated that pirfenidone prevents congestive-HF-induced TGF-β1 overexpression in the atrium [16]. The gene discussed is TGFB1; the disease is hydrops fetalis.