Plasma soluble neprilysin levels are unchanged during recovery after decompensation of heart failure: a matter of the magnitude of the changes in systemic haemodynamics?

This commentary refers to ‘The heart regulates the endocrine response to heart failure: cardiac contribution to circulating neprilysin’, by M. Arrigo et al., on pages 1794–1798. Arrigo et al. 1 observed that implantation of a total artificial heart contributed to changes in circulating neprilysin levels in two patients with heart failure (HF). This clearly differs from the physiological changes seen in patients during recovery following acute decompensation of HF in clinical settings. Thus, much about the changes in soluble neprilysin (sNEP) levels during ‘natural’ recovery in patients with acute decompensated HF (ADHF) remains unknown. We tested the hypothesis that HF severity is associated with changes in sNEP levels in patients with ADHF. Using a modified sandwich immunoassay (Santa Clara, CA, USA),2 we measured plasma sNEP levels in 51 ADHF patients upon admission (AD) to our hospital and before discharge (BD). The median hospital stay was 19 days [interquartile (IQR) 14–34 days].