Consistent with previous biomarker studies in chronic heart failure where CT-proET-1 correlated with B-type natriuretic peptide (BNP)34, and log CT-proET-1 correlated with log N-terminal-proBNP (NT-proBNP)35, here CT-proET-1 correlated with NT-proBNP (Fig. 4D). Here, NPPB is linked to congestive heart failure.