Even though most of the studies have reported the relationship between higher ET-1 related peptides and clinical adverse outcomes of HF patients,[5,11,12] there were still several studies holding the opposite opinion.[13,14] To address this issue, we performed a meta-analysis to assess the values of ET-1, big ET-1, and CT-proET-1 in predicting prognosis in HF patients. The gene discussed is EDN1; the disease is hydrops fetalis.