NPPB and hydrops fetalis: In contrast, another interesting study, which included 109 fully treated patients with HF, revealed that from the evaluated parameters: ET-1 level, New York Heart Association (NYHA) class, N-terminal proatrial natriuretic factor level, BNP level, left ventricular ejection fraction and age, only ET-1 had a significant and independent impact on prognosis and was able to identify a specific subgroup of patients who had an exceptionally high risk of mortality [58].