Acute kidney injury in octogenarians after heart valve replacement surgery: a study of two periods over the last decade.

BACKGROUND: Data on postoperative acute kidney injury (AKI) in octogenarians are limited. This study examines the AKI occurrence and clinical impact in octogenarians following open-heart valve replacement surgery in two periods over the last 15 years.

METHODS: A total of 452 consecutive octogenarians (non-kidney transplant and non-dialysis) who underwent heart valve replacement at the Mayo Clinic during the years 2011-13 (contemporary cohort) were examined. The results were compared with a comparable 209 consecutive octogenarians in 2002-03 (past cohort). Pre-existing chronic kidney disease (CKD) was defined based on estimated glomerular filtration rate (Chronic Kidney Disease Epidemiology Collaboration formula). Outcomes included postoperative AKI defined by the Acute Kidney Injury Network (AKIN) criteria, length of hospital stay (LOS), discharge disposition and patient survival (hospital and 1 year).

RESULTS: AKI occurrence in the contemporary cohort was lower than the past cohort (35% versus 47%, respectively, P < 0.003). Compared with the past cohort, the contemporary cohort had fewer known perioperative AKI risk factors (pre-existing CKD, comorbidity, heart failure, surgical duration, cross-clamp time, blood transfusion and large-volume intravenous fluids). In both periods, AKI adversely impacts mortality, LOS and discharge to a care facility.

CONCLUSIONS: Postoperative AKI in octogenarians following heart valve replacement surgery has declined over the last decade. As a result, the AKI-attributable percentage mortality has accordingly decreased. However, AKI continues to exert a heavy morbidity and mortality burden. These results are highly pertinent to practice since the octogenarian population is growing.