Spot urinary sodium in acute decompensation of advanced heart failure and dilutional hyponatremia: insights from DRAIN trial

Background Diuretic resistance portends a poor prognosis in acute heart failure, especially in advanced stages. Early identification of a poor response to diuretics may help to improve treatment and outcomes. Spot natriuresis (UNa + ) at 2 h from the start of intravenous furosemide has been proposed as an early indicator of diuretic response. Our paper aimed to determine the role of early natriuresis in patients hospitalized with advanced chronic heart failure (ACHF) and high risk of diuretic resistance. Methods and results We performed a sub-analysis of the DRAIN trial, a randomized clinical trial on 80 patients with acute decompensation of ACHF (NYHA IV, EF ≤ 30%) with low systolic blood pressure (≤ 110 mmHg) and dilutional hyponatremia (sodium ≤ 135 mMol/L) at admission. Patients were divided into two groups according to spot urinary sodium excretion (high: UNa + > 50 or low: ≤ 50 mEq/L) at 2 h from furosemide administration. Twenty-eight patients (35%) showed a low natriuretic response. As compared to the other patients, this group showed lower daily urinary output (2275 ± 790 vs 3849 ± 2034 mL, p < 0.001), lower body weight reduction after 48 h (1.55 ± − 1.66 vs − 3.55 ± − 2.93 kg, p < 0.001), higher incidence of worsening renal function (32% vs 10%, p 0.02) and increasing rather than reducing NT-proBNP at 72 h ( p 0.02). Conclusions In patients with ACHF and dilutional hyponatremia, low natriuresis after furosemide is an early marker of poor diuretic response and correlates with higher NT-proBNP and higher incidence of worsening renal function at 72 h. Graphic abstract