Signs and symptoms of volume overload are the most frequent reason for hospital admission in patients with heart failure. During such episodes of acute heart failure, diuretics are the mainstay treatment. Good diuretic efficiency with complete decongestion is associated with better outcomes. However, these targets remain challenging in clinical practice as diuretic resistance occurs frequently and a normal volume status cannot be readily assessed.

Spot urine sodium assessment is a reliable indicator of diuretic response. Its use in acute heart failure has been recommended by the new guidelines on heart failure of the European Society of Cardiology, with the aim of detecting diuretic resistance early to allow appropriate treatment intensification.

Observational data suggest that a high urine sodium concentration on spot urine sample after diuretic therapy indicates persistent congestion, even when clinical signs of volume overload are not obvious. Therefore, hypothetically, intensive diuretic therapy in acute heart failure until complete disappearance of clinical signs of volume overload and a urine sodium concentration drop <80 mmol/L, with immediate step‑up care in case of diuretic resistance (i.e., low urine sodium concentration with persistent signs of volume overload), may improve the quality of decongestion and potentially clinical outcomes.

The DECONGEST study prospectively examines a systematic approach to diuretic therapy in acute heart failure, based upon serial assessment of sodium concentration on spot urine samples after diuretic administration.