Acute Renal Failure in Coronary Artery Bypass Surgery: Independent Effect of Cardiopulmonary Bypass

BACKGROUND: Acute renal failure after cardiac surgery is associated with a high morbidity and mortality, particularly when associated with hemodialysis. The aim
of the study was to investigate whether the use of cardiopulmonary bypass increased the risk of developing acute renal failure.

METHODS: The 2199 consecutive patients undergoing isolated coronary artery bypass grafting between
January 2000 and March 2002 were retrospectively analyzed. Patients with significant preoperative renal dysfunction (preoperative serum creatinine > 200
micromol/L) were excluded. A multivariate logistic regression model was constructed to identify independent risk factors for the development of acute
renal failure.

RESULTS: In the study, 53 patients (2.4%) developed acute renal failure before hospital discharge. The crude incidences of acute renal failure for isolated coronary artery bypass grafting in the on- and off- pump groups were 2.9% and 1.4%, respectively (p = 0.031). There were 1483 patients who underwent on-pump surgery whereas 716 patients were in the off-pump group. The two groups were broadly comparable on many variables. The off-pump group were slightly younger on average (63.6 versus 64.9 years old Äp = 0.017Å), but had more angina class IV patients (39.5% versus 28.9% Äp < 0.001Å) and a greater proportion of redo surgery (4.1% versus 1.6% Äp < 0.001Å). The on-pump group had more patients with three-vessel disease (82.8% versus 74.3% Äp < 0.001Å). The logistic regression model identified use of cardiopulmonary bypass as an independent risk factor for the development of acute renal failure (odds ratio 2.64 Ä95% confidence intervals 1.27 to 5.45Å). Other independent predictors of acute renal failure were preoperative creatinine levels, diabetes, emergency operations, increasing age, increasing body mass index, and peripheral vascular disease. CONCLUSIONS: Cardiopulmonary bypass is associated with significantly increased risk of acute renal failure following isolated coronary artery bypass surgery.