Acute Kidney Injury After On-pump or Off-pump Coronary Artery Bypass Grafting in Elderly Patients

Background: An exploratory analysis of the German Off Pump Coronary Artery Bypass Grafting in Elderly Patients (GOPCABE) trial was performed to investigate the effect of off-pump coronary artery bypass grafting (CABG) on kidney function after the operation.

Methods: Data on kidney function were available from 1,612 patients, representing 67% of the study population. Preoperative kidney function was graded according to the glomerular filtration rate. Acute kidney injury (AKI) within the first week after the operation was defined and classified according to the Acute Kidney Injury Network (AKIN) criteria. The incidence and severity of AKI was compared between patients operated on on-pump or off-pump.

Results: Impaired kidney function was seen in 642 patients (40%), and 19 patients had preexisting end-stage kidney disease. AKI of any severity occurred in half of all patients undergoing CABG, with AKIN stage 1 accounting for most of the cases. The incidence and severity of AKI in patients undergoing on-pump vs off-pump CABG was AKIN stage 1: 298 (37%) vs 329 (42%); AKIN stage 2: 38 (5%) vs 43 (5%); and AKIN stage 3: 44 (6%) vs 44 (6%), which did not differ significantly (p=0.174). New renal replacement therapy was necessary in 3.2% (on-pump) and in 2.7% (off-pump) of all patients. Stratification according to preoperative kidney function yielded comparable frequencies of AKI for on-pump and off-pump CABG.

Conclusions: AKI was common in elderly patients undergoing CABG, but deterioration of kidney function requiring renal replacement therapy was a rare event. Off-pump CABG was not associated with decreased rates or reduced severity of AKI in elderly patients.