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

Abstract

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. 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 > or =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. 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. 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.