Objectives: Acute kidney insuffciency is a prevalent and serious disease that follows coronary artery bypass graft (CABG). One of the important symptoms of acute renal failure (ARF) is the increased level of urea and serum creatinine. This study examined the rate of renal failure in patients undergoing on-pump and off-pump CABG. 

Materials and Methods: In this descriptive–comparative survey, we selected the patients undergoing heart surgery. Levels of urea, creatinine, sodium, potassium and urinary output were controlled and recorded in the frst days of admission and ICU discharge. Data collection tool was a checklist, the frst part included demographic information and the second part was related to the information on kidney function. The data were analyzed using SPSS version 21.0.

Results: The fndings of this study showed a statistically signifcant difference in terms of age and the incidence of renal failure based on the increased levels of urea and serum creatinine before and after CABG (P<0.05). Results of this study also showed that the incidence of renal failure signifcantly increased after CABG based on the levels of urea and serum creatinine (P<0.00). No considerable difference was observed between 2 surgery procedures (on-pump and off-pump) in terms of renal failure incidence (P>0.05).

Conclusions: Patients’ age was an important factor for kidney insuffciency following CABG. Type of the surgery (on- and off-pump) and gender had no influence on the incidence rate of ARF. Stronger measures to protect the kidneys in older patients may reduce this high-risk complication.