Abstract
BACKGROUND: In the setting of acute decompensated heart failure, worsening renal function (WRF) and improved renal function (IRF) have been associated with similar hemodynamic derangements and poor prognosis. Our aim was to further characterize IRF and its associated mortality risk. METHODS AND RESULTS: Consecutive patients with a discharge diagnosis of congestive heart failure at the Hospital of the University of Pennsylvania were reviewed. IRF was defined as a ≥20% improvement and WRF as a ≥20% deterioration in glomerular filtration rate. Overall, 903 patients met the eligibility criteria, with 31.4% experiencing IRF. Baseline venous congestion/right-side cardiac dysfunction was more common (P ≤ .04) and volume of diuresis (P = .003) was greater in patients with IRF. IRF was associated with a greater incidence of preadmission (odds ratio [OR] 4.2, 95% confidence interval [CI] 2.6-6.7; P < .0001) and postdischarge (OR 1.8, 95% CI 1.2-2.7; P = .006) WRF. IRF was associated with increased mortality (adjusted hazard ratio 1.3, 95% CI, 1.1-1.7; P = .011), a finding largely restricted to patients with postdischarge recurrence of renal dysfunction (P interaction = .038). CONCLUSIONS: IRF is associated with significantly worsened survival and may represent the resolution of venous congestion-induced preadmission WRF. Unlike WRF, the renal dysfunction in IRF patients occurs independently from the confounding effects of acute decongestion and may provide incremental information for the study of cardiorenal interactions.