Mortality and pathophysiology of acute kidney injury according to time of occurrence in acute heart failure.

Aims: Acute kidney injury (AKI) during acute heart failure (AHF) is common and associated with increased morbidity and mortality. The underlying pathophysiological mechanism appears to have prognostic relevance; however, the differentiation of true, structural AKI from hemodynamic pseudo-AKI remains a clinical challenge.

Methods And Results: The Basics in Acute Shortness of Breath Evaluation Study (NCT01831115) prospectively enrolled adult patients presenting with AHF to the emergency department. Mortality of patients was prospectively assessed. Haemoconcentration, transglomerular pressure gradient (n = 231) and tubular injury patterns (n = 253) were evaluated to investigate pathophysiological mechanisms underlying AKI timing (existing at presentation vs. developing during in-hospital period). Of 1643 AHF patients, 755 patients (46%) experienced an episode of AKI; 310 patients (19%; 41% of AKI patients) presented with community-acquired AKI (CA-AKI), 445 patients (27%; 59% of AKI patients) developed in-hospital AKI. CA-AKI but not in-hospital AKI was associated with higher mortality compared with no-AKI (adjusted hazard ratio 1.32 [95%-CI 1.01-1.74]; P = 0.04). Independent of AKI timing, haemoconcentration was associated with a lower two-year mortality. Transglomerular pressure gradient at presentation was significantly lower in CA-AKI compared to in-hospital AKI and no-AKI (P < 0.01). Urinary NGAL ratio concentrations were significantly higher in CA-AKI compared to in-hospital AKI (P < 0.01) or no-AKI (P < 0.01).

Conclusions: CA-AKI but not in-hospital AKI is associated with increased long-term mortality and marked by decreased transglomerular pressure gradient and tubular injury, probably reflecting prolonged tubular ischemia due to reno-venous congestion. Adequate decongestion, as assessed by haemoconcentration, is associated with lower long-term mortality independent of AKI timing.