Prognostic significance of acute kidney injury and small increases in creatinine concentration during acute decompensation of heart failure.

Background: Diagnosis of acute kidney injury (AKI) during acute decompensations of heart failure (ADHF) remain challenging. We analysed the incidence and prognosis of AKI, and the significance of small increases of creatinine, during ADHF and after stabilization.

Methods: Patients admitted for ADHF were prospectively included. Creatinine was measured at admission, 48h thereafter and 24h before discharge. AKI was diagnosed when creatinine increased≥50% in 7 days (RIFLE criteria) or≥0.3mg/dL in 48h (AKIN criteria) during admission. Changes between baseline creatinine (measured within 3-month before admission) and one month after discharge were assessed, to seek for residual impairment of renal function and its significance.

Results: Two hundred and four patients were included. Incidence of AKI was 28.4% (n=58). Creatinine peaked by day 5 in patients with AKI vs. non-AKI (1.9 vs. 1.1mg/dL; P<.000) and remained significantly higher among patients with AKI 3 months after discharge (increase of 20 vs. 4%; P=.013). Twelve-months mortality was associated with increases in cystatin C, NT-proBNP and AKI (15.5 vs. 44.8%, P<.000), being the latter the most powerful independent predictor of death ?Exp(B)=5.34; P=.009?. Minor increases in creatinine (20% or 0.2mg/dL) during admission associated lesser 12-months survival (P=.033 and P=.019, respectively). Increases in creatinine≥10% between baseline and one month after discharge are associated with higher mortality (12.6 vs. 22.5%, P=.044).

Conclusions: AKI is a strong predictor of mortality after ADHF. Minor increments in creatinine concentrations, below the accepted threshold for AKI definition, are prognostically meaningful.