In patients presenting to Emergency Department with Shortness of Breath a fast diagnosis distinguishing between lung or cardiac diseases is mandatory.Quantitative assessment of congestion could be useful in the management of acute heart failure (AHF) patients. No data are available on the diagnostic and prognostic role of quantitative fluid retention evaluated by bioelectrical impedance vector analysis (BIVA) in AHF patients at the moment of their emergency department (ED) presentation. Conclusions: In AHF patients a quantitative evaluation of fluid congestive status obtained by BIVA at ED arrival provides significant additive diagnostic and 30-day prognostic value to BNP. This could lead to a better management of these patients with possible improvement in reducing subsequent CV events after hospital discharge.