The dynamics of urine sodium concentration after intra-venous furosemide in patients with acute heart failure

Abstract Background The urine sodium concentration measured at 2 hours after the administration of intravenous (IV) furosemide in patients with acute heart failure (AHF) is recommended as a marker to assess the responsiveness to IV furosemide. However, little is known regarding the dynamics of natriuresis in the very acute phase after IV furosemide and its association with prognosis in patients with AHF. Purpose The aim of this study is to investigate the dynamics of natriuresis in the very acute phase after IV furosemide and its prognostic implication in patients with AHF. Methods DIURESIS-AHF (Diuretic Resistance Measured by Sodium Excretion and Urine Output in Acute Heart Failure) is a multicenter, prospective, and observational study that evaluated the urine samples at the time of 0h, 1h, 2h, 6h, and 24h after the first administration of IV furosemide in hospitalized patients with AHF. Results After excluding 20 patients who needed additional IV furosemide within the first 6 hours, and 9 patients with missing data about 1h-spot urine sample, 84 patients with AHF (79±8 years, 55% men) were analyzed. Median N-terminal pro-brain natriuretic peptide levels at admission were 4722 [interquartile: 2616-8095] pg/mL, and median first IV furosemide doses were 20 [interquartile:20-20] mg. 29 combined event of all-cause death and heart failure rehospitalization were observed during a 1-year follow-up after registration. Urine sodium concentration corrected for urine creatinine concentration peaked 1 hour and decreased at 2 hours after IV furosemide. Kaplan-Meier curve analysis indicated that 1h urine sodium concentration below 50 mEq/L was significantly associated with a high incidence of composite endpoint (Log-rank P=0.033), and this association was retained even after adjusting for age and sex (hazard ratio, 2.37 [95% CI, 1.03-5.45]; P=0.042), but 2h urine sodium below 50 mEq/L was not associated with a poor prognosis (Log-rank; P=0.630). Conclusions Urinary sodium excretion after IV furosemide administration peaked at 1 hour after IV furosemide and decreased at 2 hours in patients with AHF. The urine sodium concentration below 50 mEq/L at 1 hour, but not 2 hours, was associated with adverse events.Urine Na trajectoriesKaplan Meier curves