Acute declines in kidney function occur in approximately 20%-30% of patients with acute decompensated heart failure, but its significance is unclear, and the importance of its context is not known. This study aimed to determine the prognostic value of a decline in kidney function in the context of decongestion among patients admitted with acute decompensated heart failure.

Using data from patients enrolled in the Ultrafiltration in Decompensated Heart Failure with Cardiorenal Syndrome Study (CARRESS) and Diuretic Optimization Strategies Evaluation (DOSE) trials, we used multivariable Cox regression models to evaluate the association between decline in estimated glomerular filtration rate (eGFR) and change in N-terminal pro-b-type natriuretic peptide (NT-proBNP) with a composite outcome of death and rehospitalization, as well as testing for an interaction between the two.

Among 435 patients, in-hospital decline in eGFR was not significantly associated with death and rehospitalization (hazard ratio [HR] = 0.89 per 30% decline, 95% confidence interval [CI] 0.74, 1.07), whereas decline in NT-proBNP was associated with lower risk (HR = 0.69 per halving, 95% CI 0.58, 0.83). There was a significant interaction (P = 0.002 unadjusted; P = 0.03 adjusted) between decline in eGFR and change in NT-proBNP where a decline in eGFR was associated with better outcomes when NT-proBNP declined (HR = 0.78 per 30% decline in eGFR, 95% CI 0.61, 0.99), but not when NT-proBNP increased (HR = 0.99, 95% CI 0.76, 1.30).

Decline in kidney function during therapy for acute decompensated heart failure is associated with improved outcomes as long as NT-proBNP levels are decreasing as well, suggesting that incorporation of congestion biomarkers may aid clinical interpretation of eGFR declines.