Off-pump coronary artery bypass grafting does not preserve renal function better than on-pump coronary artery bypass grafting: results of a case-matched study

Objective: Controversy exists regarding the perioperative renal effects of off-pump versus on-pump coronary artery bypass grafting. Large case-matched and randomized comparisons have shown conflicting results. This study focuses on this clinical controversy.

Methods: We studied 5589 consecutive patients from a single center who underwent off-pump or on-pump coronary artery bypass grafting between 2002 and 2010. All preoperative, intraoperative, and postoperative data were prospectively collected. Patients were matched by using a nearest neighbor matching estimation method for average treatment effects, with bias correction (Stata 11.2, StataCorp, College Station, Tex). The matching characteristics were age, gender, body mass index, hypertension, diabetes, peripheral vascular disease, cerebrovascular disease, left ventricular grade, preoperative serum creatinine, operative priority, and Cardiac Anesthesia Risk Evaluation score.

Results: The mean patient age was 64.9 ± 10.0 years, and 4387 (78.5%) were male. Mean calculated preoperative creatinine clearance was 82.0 ± 32.6 mL/min. Perioperative mortality was 1.5% with off-pump coronary artery bypass grafting and 1.7% with on-pump coronary artery bypass grafting (P = .6). The mean change in creatinine clearance, from the preoperative value to the lowest postoperative value, was -6.3 ± 14.1 mL/min with off-pump coronary artery bypass grafting versus -5.0 ± 15.5 mL/min with on-pump coronary artery bypass grafting (P = .06). After matching, patients undergoing off-pump coronary artery bypass grafting had a greater creatinine increase and greater loss of creatinine clearance postoperatively compared with patients undergoing on-pump coronary artery bypass grafting (both P < .05). Requirements for de novo postoperative dialysis were equivalent at 2.6% in off-pump coronary artery bypass grafting versus 2.1% in on-pump coronary artery bypass grafting (P = .4). Median postoperative hospital stay was 8 days in both groups (P = .8).

Conclusions: Off-pump coronary artery bypass grafting does not preserve renal function to a greater extent than on-pump coronary artery bypass grafting. In fact, a trend to the reverse exists with no clinically harmful effects.