Late dialysis rate for coronary artery bypass grafting patients with moderate-to-severe renal impairment: comparison between off-pump and conventional method

Background: Whether off-pump coronary artery bypass grafting has a late renal protective advantage over conventional coronary arterial bypass grafting with cardiopulmonary bypass use is controversial. Methods: From 1997 to 2004, 2102 cases of isolated coronary arterial bypass grafting were collected and analyzed, 1116 (53%) in the cardiopulmonary bypass group and 986 (47%) in the off-pump coronary artery bypass grafting group. Cases were stratified by preoperative estimated glomerular filtration rate into three renal groups: 1012 (48%) in group 1, with glomerular filtration rates ≥60 ml/h, 864 (41%) in group 2, with glomerular filtration rates of 30-60 ml/h, and 226 (10.8%) in group 3, with glomerular filtration rates <30 ml/h, but without dialysis before surgery. Results: The in-hospital mechanical renal replacement therapy rates were 2.0%, 4.6%, and 26.1%, respectively, for the three renal groups that underwent coronary artery bypass grafting with conventional cardiopulmonary bypass, and 1.1%, 3.4%, and 14.0%, respectively for the three renal groups that underwent off-pump coronary artery bypass grafting. After risk adjustment, cardiopulmonary bypass use did not show statistical significance for in-hospital mechanical renal replacement therapy (p = 0.314, 0.524, 0.150, respectively, across renal groups 1-3). At the end of the 4-year follow-up period, 99.1%, 97.2%, and 78.6%, respectively, of patients were free of mechanical renal replacement therapy across the three renal groups (p = 0.0097 between renal groups 1 and 2; p < 0.001 between renal groups 2 and 3). Cox regression analysis for renal groups 2 and 3 revealed that cardiopulmonary bypass use was not a risk factor for mid-term mechanical renal replacement therapy (p = 0.452), but preoperative glomerular filtration rate, hypercholesterolemia, insulin-requiring diabetes, young age at surgery, female gender, and in-hospital mechanical renal replacement therapy use were. Conclusion: Patient characteristics, rather than operative strategy of using off-pump or conventional coronary artery bypass grafting, influence the mid-term mechanical renal replacement therapy rate for patients with glomerular filtration rates <60 ml/min.