Basal natriuresis as a predictor of diuretic resistance and clinical evolution in acute heart failure

Abstract Introduction Current clinical guidelines recommend serial measurement of natriuresis to detect diuretic resistance (DR) and to adjust the dose of furosemide in patients with acute heart failure (AHF) (1-5). However, multiple natriuretic dosages could make more complex the AHF management. Our objective was to correlate a single measurement of basal natriuresis (BN) on admission with the development of DR and cardiovascular (CV) events in patients hospitalized for AHF and during early outpatient follow-up (6-11). Methodology Prospective, multicenter study that included patients admitted to the coronary care unit (CCU) for AHF. Patients in shock or with creatinine >2.5 mg% at admission were excluded. Patients included received 40 mg of intravenous furosemide on admission, BN was measured in the first urination (the result was blinded to the treating physician), and subsequent diuretic treatment was guided by a pre-established protocol. The BN was considered low if it was <70 meq/L. The DR was defined as a combined endpoint composed of the requirement for intravenous furosemide ≥240 mg/day, tubular diuretic blockade (TB), hypertonic saline solution (HSS) or renal replacement therapy (RRT). In-hospital CV mortality was evaluated, as well as CV mortality and AHF readmissions at 60-day post-discharge follow-up. Results 157 patients were included, 56% men, with a median age of 74 years. The median BN was 103 meq/L (IQR 74-122), and BN was low in 22% of the cohort (N=34). DR was presented in 19% (N=30), 12.7% (N=20) required furosemide ≥240 mg/day, 8% (N=13) TB, 1 patient HSS and 4% (N=6) RRT. In-hospital CV mortality was 5.7%, CV mortality at 60-day follow-up 6.8%, and AHF readmissions at 60-day follow-up 12.2%. The group with low BN presented more DR (44% vs 12%; p 0.0001; RR 0.27; 95% CI 0.15-0.5), persistence of congestion at 48 hs (26.5% vs 11.4%; p 0.05; RR 0.48; IC 95% 0.22-1), administration of furosemide ≥240 mg/day (29% vs 8%; RR 0.27; 95% CI 0.12-0.61; p 0.003), more cumulative dose of furosemide at 72 hours (220mg [IQR 180-440] vs 160mg [IQR 100-180]; p 0.0001), use of TB (20.6 vs 4.9%; p 0.008; RR 0.23; 95%CI 0.08-0.65) and RRT (11.8 vs 1.6%; p 0.02; RR 0.14; 95%CI 0.02-0.72). Low BN was associated with in-hospital worsening of AHF (26.5% vs 9%; p 0.016; RR 0.34; 95%CI 0.15-0.74), inotropics use (21% vs 7%; p 0.048; RR 0.36; 95%CI 0.14 -0.88) or mechanical respiratory assistance (12% vs 2%; p 0.02; RR 0.14; 95%CI 0.02-0.72). Low BN presented higher in-hospital CV mortality (12% vs 4%; p 0.1), without association with endpoints in outpatient 60-day follow-up. Conclusions In patients hospitalized for AHF, low BN was associated with DR, persistence of congestion, need for more aggressive decongestion strategies, and a worse in-hospital clinical outcome