Hyponatremia is the most common electrolyte abnormality in the hospital setting and is associated with higher in-hospital mortality, 60-day mortality, and longer length of hospitalization.1–5 These findings have also been shown for patients hospitalized with heart failure (HF).6–10 Despite these associations, the importance of hyponatremia as an influenc- ing factor for acute treatment decisions in acute HF remains equivocal because of a paucity of prospective data. Notably,a previous study found moderate to severe hyponatremia, es- pecially when