Big Endothelin-1 (BigET-1) is a peptide of 38 amino acids and is the precursor of Endothelin-1 (ET-1), consisting of amino acids 1-21 (http://www.uniprot.org/uniprot/P05305). ET-1 is a potent vasoconstrictor and is produced by vascular endothelial cells. Accordingly, it has a wide tissue distribution (http://www.ncbi.nlm.nih.gov/UniGene/ESTProfileViewer.cgi?uglist=Hs.511899). The cleavage of BigET-1 by the Endothelin-converting enzyme (ECE) converts BigET-1 to Endothelin (ET) and to a C?terminal fragment. The half-life of ET-1 (1-21) in plasma is less than one minute, which may preclude its use as a diagnostic marker, whereas clearance of the precursor peptide BigET-1 is much slower. As Big-Endothelin-1 is produced at amounts equimolar to ET-1 and has higher plasma stability, it is more suitable for diagnostics and monitoring of heart failure (Gergei et al., 2018). Hence, Big ET-1 has the same physiological role as ET-1 while being a more reliable marker.