Impact of Preoperative Renal Dysfunction in Patients Undergoing Off-Pump Versus On-Pump Coronary Artery Bypass

Abstract

The impact of the degree of renal dysfunction (RD) in patients undergoing coronary artery bypass grafting (CABG) ranging from normal to dialysis-dependence is not well defined. A retrospective review of 14,199 patients undergoing isolated, primary CABG from January 1996 to May 2009 at Emory Healthcare was performed. The estimated glomerular filtration rate (eGFR) was estimated by the Modification of Diet in Renal Disease formula: mild RD (eGFR 60 to 90 mL/min/1.73 m2), moderate RD (eGFR 30 to 59), severe RD (eGFR<30). A propensity scoring was used to balance the groups with 46 preoperative covariates. Multivariable logistic and Cox regression methods were used to determine the independent association of eGFR with mortality. Adjusted odds ratios were calculated for outcomes using the normal eGFR group as the reference. Kaplan-Meier curves were created to estimate long-term survival. A total of 8,086 patients (57.0%) underwent off-pump coronary artery bypass (OPCAB) while 6,113 (43.0%) underwent on-pump CAB. Preoperative RD was common: Normal eGFR (n=3,503/14,199 [24.7%]); mild RD (7,236/14199 [51.0%]); moderate RD (2,860/14,199 [20.1%]); severe RD (283/14,199 [2.0%]); and preoperative dialysis (317/14,199 [2.2%]). Moderate to severe RD or preoperative dialysis was associated with worse adjusted in-hospital mortality: mild RD (odds ratio [OR] 1.42; 95% confidence interval [CI] 0.93 to 2.16; p=not significant); moderate RD (OR 3.55; 95% CI 2.32 to 5.43; p<0.05]; severe RD (OR 8.84; 95% CI 4.92 to 15.9; p<0.05); and dialysis-dependent (OR 9.64; 95% CI 5.45 to 17.0; p<0.05). Adjusted long-term survival was worse across levels of RD. The OPCAB patients with moderate to severe RD had worse long-term survival than on-pump CAB patients; however, the surgery types were similar among normal, mild, and dialysis patients. Preoperative RD is common in the CABG population and is associated with diminished long-term survival. Improved early outcomes in patients with RD undergoing OPCAB diminished with worsening RD.