Prognostic effect of worsening renal function and spot urinary sodium in acute heart failure: a post-hoc analysis DIUR-AHF study

Background Worsening renal function (WRF) was common in acute heart failure(AHF) and could be related to poor outcome.However, when WRF is associated with aggressive diuretic treatment and effective decongestion, its negative prognostic value is not confirmed.A recent consensus document1 recommended, in AHF, the urine spot sodium together with urine output after loop diuretics administration, to evaluate diuretic response avoiding loop diuretics under or over treatment. The aim of this study is to evaluate the presence of WRF and low urinary sodium in relation to congestion and outcome. Methods We studied patients with AHF screened for DIUR-AHF study. WRF was defined as an in-hospital rise in serum creatinine ≥ 0.3 mg/dl or estimated glomerular filtration rate (eGFR) reduction ≥ 20%. Low urinary sodium (U Na) was defined as urinary spot sodium <70 meq/L. A congestion score was calculated both at admission and at discharge. The following symptoms and signs were evaluated: pulmonary rales, peripheral edema, dyspnea and pulmonary congestion at chest X-ray (4 total points). Persistence of congestion was defined as a congestion score at discharge ≥ 2. Patients were followed for 6 months, through a scheduled outpatient visit or phone contact, to collect prognostic data as mortality and HF re-hospitalization. Results 370 AHF patients were included in this analysis. Mean age was 76±11 years old, with a prevalence of gender male (54%). Mean of left ventricular ejection fraction was 33±11%, mean N-terminal pro B-type natriuretic peptide (NTproBNP) was 12685±11453 pg/mL, mean creatinine was 1,56±0,70 mg/dL, mean eGFR was 48±31 ml/min/m2, mean blood urea nitrogen (BUN) was 74±46 mg/dl and mean spot U Na was 69±20 meq/L. The rate of WRF was 26% and the rate of low urinary sodium was 46%. Dividing our sample according U Na levels, patients with low U Na showed higher oral Loop diuretic dosage before admission with respect to patients with normal U Na (132±70 mg/die vs 105±53 mg/die; p<0.001). Dividing our population according to WRF presence, there were not significant differences between the two groups regarding home loop diuretic therapy (p=0.444). The classification of our population according to the presence or not of WRF and the low U Na identified 4 groups: group 1 no WRF and normal U Na, group 2 No WRF and low U Na, group 3 WRF and normal U Na, group 4 WRF and low U Na. Although not statistically significant, we found a higher prevalence of persistence of congestion in group 2 and 4 with respect to 3 and 1 (34% and 35% vs 15% and 28%; p=0.08). Univariate analysis showed the significant association between group 2 (HR 1.87[1.27-2.76]; p=0.002) and group 4 (HR 2.17[1.34-3.52]; p=0.002) with poor post-discharge outcome. Group 3 was not significant (p=0.781).[Figure 1] Conclusions In AHF patients WRF was related to poor prognosis only when it occurs together with to low U Na.