Abstract The administration of hypertonic saline (HS) in decompensated heart failure (HF) seems counterintuitive, given the concept that sodium is universally harmful for these patients. However, increasingly, strict sodium restrictions have been questioned due to the lack of proven benefits. On the other hand, we know that in acute HF complicated with diuretic resistance, there is hyperactivation of the renin-angiotensin-aldosterone system (RAAS), resulting in a state of excessive increase in renal avidity for sodium, hindering the action of loop diuretics. […]