Abstract
BACKGROUND: Treatment of acute decompensated heart failure (ADHF) with loop diuretics, such as furosemide, is frequently complicated by insufficient urine sodium excretion. We hypothesize that insufficient natriuretic response to diuretic therapy, characterized by lower urine sodium (UNa) and urine furosemide, is associated with subsequent inadequate decongestion, worsening renal function, and adverse long term events. METHODS AND RESULTS: We enrolled 52 consecutive patients with ADHF and measured serum and urine sodium (UNa), urine creatinine (UCr), and urine furosemide (UFurosemide) levels on a spot sample taken after treatment with continuous intravenous furosemide, and followed clinical and renal variables as well as adverse long-term clinical outcomes (death, rehospitalizations, and cardiac transplantation). We observed similar correlations between UNa:UFurosemide ratio and UNa and fractional excretion of sodium (FENa) with 24-hour net urine output (r = 0.52-0.64, all P < .01) and 24-hour weight loss (r = 0.44-0.56; all P < .01). Interestingly, FENa (but not UNa or UNa:UFurosemide) were influenced by estimated glomerular filtration rate (eGFR). We observed an association between lower UNa:UFurosemide with greater likelihood of worsening renal function (hazard ratio [HR] 3.01; P = .02) and poorer adverse clinical outcomes (HR 1.63, P = .008) after adjusting for age and eGFR. Meanwhile, both diminished weight loss and net fluid output over 24 hours of continuous intravenous furosemide were observed when UNa:UFurosemide ratios were <2 mmol/mg or when UNa <50 mmol. CONCLUSION: In patients with ADHF receiving continuous furosemide infusion, impaired natriuretic response to furosemide is associated with greater likelihood of worsening renal function and future adverse long-term outcomes, independently from and incrementally with decreasing intrinsic glomerular filtration.