Acute Renal Dysfunction Does Not Develop More Frequently Among Octogenarians Compared to Septuagenarians after Cardiac Surgery

Abstract

We tested the hypothesis that octogenarians develop more frequently renal dysfunction compared with septuagenarians after cardiac surgery. A retrospective, observational study on an age-, gender- and operation-matched cohort of 598 patients, (299 octogenarians vs. 299 septuagenarians) who underwent cardiac surgery between January 2006 and August 2009, was performed. Kidney function was estimated with the abbreviated Modification in Renal Disease equation and acute kidney injury was defined as a decrease of glomerular filtration rate ≥50%. Operations included 246 coronary, 198 isolated valve, and 154 combined coronary and valve procedures. Mean logistic EuroSCORE was 8.5% in septuagenarians and 13.2% in octogenarians. Octogenarians had significantly more frequent and estimated GFR < 60 mL/min/1.73 m² (44 vs. 34.4%, p = 0.02). The incidence of dialysis-dependent acute kidney failure did not differ between both groups (6.7 vs. 5.4%, p = 0.60). Postoperative decline of glomerular filtration rate <25% occurred significantly more often in septuagenarians (40 vs. 30%, p = 0.02). Septuagenarians with a preoperative GFR < 60 mL/min/1.73 m² had a higher 30-day mortality compared with patients with a GFR > 60 mL/min/1.73 m² (10.9 vs. 3.1%, p = 0.02). Overall, 30-day mortality in octogenarians was 7.7% without significant differences with respect to preoperative GFR. Octogenarians do not develop acute kidney failure more frequently than their matched septuagenarian counterparts. They can be operated on at an acceptable risk for morbidity and mortality. Preoperative impaired renal function is associated with higher risk for mortality in septuagenarians.