Prognostic Impact of Acute Kidney Injury on Decompensated Heart Failure

Abstract

Introduction: Decompensated heart failure (HF) is a complex and debilitating syndrome, which constitutes a severe emergency condition with high morbidity and mortality. The kidneys play fundamental roles in the pathophysiology of HF and, in the context of decompensations, acute kidney injury (AKI) has a bilateral cause-and-effect relationship, which can significantly worsen prognosis. However, the interaction between AKI and decompensated HF is poorly understood. Objective: This study aimed to assess the occurrence of AKI in patients hospitalized due to decompensated HF and to analyze its prognostic impact during hospitalization. Methods: Prospective single-center observational study that included patients hospitalized due to decompensated HF in a tertiary-level teaching hospital, conducted between July 2017 and January 2020. Patients who developed AKI during hospitalization were compared with those who did not develop it, until hospital discharge or death. AKI was defined as a serum creatinine increase greater than or equal to 0.3 mg/dl in 48 hours, a 1.5-fold increase in baseline creatinine in seven days or urinary volume <0.5 ml/kg/h during six hours, according to the Acute Kidney Injury Network (AKIN) criteria. The endpoints analyzed were death, need for invasive mechanical ventilation (IMV) and length of hospital stay. The Wilcoxon, Mann-Whitney and unpaired student t tests were used. Results: Ninety-nine patients were included, with a mean age of 65.4 ± 14 years, of which 47 (47.5%) were male and 52 (52.5%) were female. Reduced ejection fraction was observed in 77.8% of patients, whilst 22.2% had a diagnosis of HF with preserved EF. The decompensation clinical classifications were: dry and warm = 7 (7.1%), wet and warm = 72 (72.7%), wet and cold = 15 (15.1%) and dry and cold = 5 (5.1%). The average left ventricular ejection fraction was 38.3% ± 15. AKI ocurred in 22 patients (22.2%). Comparison between patients who evolved with and without AKI showed higher mortality (36.4% vs 10.4%, p = 0.004) and the need for IMV (54.5% vs 13%, p = 0.0001) in the first group. There was no significant difference regarding the length of in-hospital stay (22.9 ± 19 vs 18.8 ± 16 days, p = 0.26). Conclusions: The occurrence of AKI was frequent in patients with decompensated HF requiring hospitalization, affecting approximately one out of five patients. This complication was significantly associated with increased mortality and the need for IMV during hospitalization.