Relationship between clinical congestion and worsening renal function after intravenous initiation of furosemide in patients with acute heart failure

To investigate if worsening renal function (WRF) appearing in some patients with acute heart failure (AHF) after intravenous furosemide initiation is influenced by severity of congestion. We conducted a retrospective secondary analysis of consecutive patients diagnosed with AHF and prospectively included in 10 Spanish emergency departments (EDs) for whom serum creatinine at ED arrival and after 2-7 days of intravenous furosemide initiation were available. Congestion was clinically evaluated by identification of 7 signs/symptoms and by chest X-ray. The outcome was WRF, defined as a delta-creatinine ≥ 0.3 mg/dL. Risk of WRF according to congestion was estimated in models adjusted by patient baseline characteristics and vitals at ED arrival, and interaction was also investigated. We included 3027 patients (median age 82 years, 56% women), and 657 (21.7%) presented WRF after intravenous furosemide initiation. When signs/symptoms were individually considered, only lower limbs edema was associated with decreased risk of WRF (20.1% vs. 24.8%; OR = 0.76, 95%CI = 0.64-0.91). After adjustment, lower limbs edema persisted inversely associated with WRF (aOR = 0.78, 95%CI = 0.65-0.94), with significant lower risk for patients ≤ 80 years and without chronic kidney disease, functional limitation, and hypoxemia (p for interaction 0.01, 0.04, 0.02 and 0.03, respectively). Neither degree of clinical congestion (number of signs/symptoms of congestion) nor radiological congestion in chest X-ray were related to WRF. Worsening renal function was associated with a higher 1-year all-cause mortality (40.1% vs 34.6%; HR = 1.27, 1.10-1.46; aHR = 1.331, 1.151-1.540). In patients with WRF, liver cirrhosis, chronic treatment with loop diuretics and renin-angiotensin system inhibitors, age (> 80 years), dementia, heart valve disease and NYHA class III-IV were associated with higher mortality. Intravenous furosemide initiation in patients with AHF without lower limbs edema must be cautious, as they are at increasing risk of developing WRF during the next following days, which in turn is associated with a higher 1-year mortality.