NPPB and hydrops fetalis: The response of NT-proBNP to carvedilol (and other vasodilator β-blockers) may be different from metoprolol, with an initial fall in natriuretic peptide levels [47-50]; since there were significant differences in the stages of HF of the studies comparing effects of β-blockers, these findings may be more due to different responses in NT-proBNP at different stages of HF, rather than heterogeneity in response to different agents.