6533b823fe1ef96bd127f598

RESEARCH PRODUCT

Early Spot Urinary Sodium and Diuretic Efficiency in Acute Heart Failure and Concomitant Renal Dysfunction

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<b><i>Objective:</i></b> In acute heart failure (AHF), early assessment of spot urinary sodium (U<sub>Na</sub>) has emerged as a useful biomarker for risk stratification and monitoring. The objective of this study was to investigate (a) whether early spot U<sub>Na</sub> predicts 24-h diuretic efficiency and (b) the clinical factors associated with early spot U<sub>Na</sub> in patients with AHF and concomitant renal dysfunction (RD). <b><i>Methods:</i></b> This is a post hoc analysis of the IMPROVE-HF trial, in which 160 patients with AHF and RD (estimated glomerular filtrate rate [eGFR] <60 mL/min/1.73 m<sup>2</sup>) were included. Diuretic efficiency was calculated as the net fluid output produced per 40 mg of furosemide equivalents in 24 h. The association between early spot U<sub>Na</sub> and diuretic efficiency and clinical variables associated with U<sub>Na</sub> were evaluated using multivariate linear regression analysis. The contribution of the exposures in the predictability of the models was assessed with the coefficient of determination (<i>R</i><sup>2</sup>). <b><i>Results:</i></b> The mean age of the study population was 78 ± 8 years. The median (interquartile range) diuretic efficiency, early spot U<sub>Na</sub>, aminoterminal pro-brain natriuretic peptide, and eGFR were 747 (490–1,167) mL, 90 mmol/L (65–111), 7,765 pg/mL (3,526–15,369), and 33.7 ± 11.3 mL/min/1.73 m<sup>2</sup>, respectively. In a multivariate setting, lower U<sub>Na</sub> was significantly and nonlinearly associated with lower diuretic efficiency (<i>p</i> = 0.001), explaining the 44.4% of the model predictability. Natremia and surrogates of congestion emerged as the main factors related to U<sub>Na</sub>. <b><i>Conclusions:</i></b> In patients with AHF and RD at presentation, early spot U<sub>Na</sub> was inversely related to 24-h diuretic efficiency.