Worsening Renal Function and Congestion in Patients with Acute Heart Failure: A Study with Bioelectrical Impedance Vector Analysis (BIVA) and Neutrophil Gelatinase-Associated Lipocalin (NGAL)

Background: Worsening renal function (WRF) is frequently observed in the setting of aggressive diuresis for the treatment of acute decompensated heart failure (ADHF) and is associated with poor outcomes in some studies. Objective: We sought to assess the relationship of WRF and congestion at discharge with events (cardiac death or heart failure hospitalization). Methods: Eighty patients with ADHF were studied. WRF was defined by an absolute increase in serum creatinine of >= 0.5 mg/dL from the values measured at the time of admission. B-type natriuretic peptide (BNP) and plasma neutrophil gelatinase-associated lipocalin (NGAL) were measured at admission and at discharge. Congestive state at discharge was assessed using bioelectrical impedance vector analysis (BIVA). Primary endpoint was time to first event defined as a combination of cardiac death or heart failure hospitalization. Receiver operating characteristic (ROC) curve analysis was used to determine the best hydration index cutoff to predict events. Kaplan-Meier event-free survival curves were constructed and compared using the log-rank test. Cox proportional hazards models were used to investigate the association with events. The criterion for determining statistical significance was p<0.05. Results: Mean age was 60.6 +/- 15 years, and 48 (60%) were male. Mean ejection fraction was 35.3 +/- 7.8%. WRF occurred in 37.5% of the sample. Baseline creatinine was associated with WRF (p<0.001), but neither admission BNP (p=0.35) nor admission NGAL (p=0.18) was predictor of WRF. Using Cox proportional hazard models, hydration index at discharge calculated with BIVA was significantly associated with events (HR 1.39, 95% CI 1.25-1.54, p<0.0001) but not WRF (HR 2.14, 95% CI 0.62-7.35, p=0.22). Conclusion: Persistent congestion at discharge was associated with worse outcomes. WRF seems to be related to hemodynamic changes during the decongestion process but not to kidney tubular injuries.