Clinical importance of urinary sodium excretion in acute heart failure.

Abstract

AimsUrinary sodium assessment has recently been proposed as a target for loop diuretic therapy in acute heart failure (AHF). We aimed to investigate the time course, clinical correlates and prognostic importance of urinary sodium excretion in AHF.Methods and resultsIn a prospective cohort of 175 consecutive patients with an admission for AHF we evaluated urinary sodium excretion 6 h after initiation of loop diuretic therapy. Clinical outcome was all‐cause mortality or heart failure rehospitalization. Mean age was 71 ± 14 years, and 44% were female. Median urinary sodium excretion was 130 (67–229) mmol at 6 h, 347 (211–526) mmol at 24 h, and decreased from day 2 to day 4. Lower urinary sodium excretion was independently associated with male gender, younger age, renal dysfunction and pre‐admission loop diuretic use. There was a strong association between urinary sodium excretion at 6 h and 24 h urine volume (beta = 0.702, P < 0.001). Urinary sodium excretion after 6 h was a strong predictor of all‐cause mortality after a median follow‐up of 257 days (hazard ratio 3.81, 95% confidence interval 1.92–7.57; P < 0.001 for the lowest vs. the highest tertile of urinary sodium excretion) independent of established risk factors and urinary volume. Urinary sodium excretion was not associated with heart failure rehospitalization.ConclusionIn a modern, unselected, contemporary AHF population, low urinary sodium excretion during the first 6 h after initiation of loop diuretic therapy is associated with lower urine output in the first day and independently associated with all‐cause mortality.