102 OPCAB is not associated with better postoperative renal function compared to CABG

Abstract

The perioperative renal effects of off-pump coronary artery bypass grafting (OPCAB) versus on-pump coronary artery bypass grafting (CABG) are not well understood. Studies have shown conflicting results and no large case-matched or randomized comparison has yet been made available in the literature. This study was conducted to compare OPCAB versus CABG in regards to changes in postoperative creatinine and postoperative creatinine clearance, when compared to preoperative values. We also examined the need for de novo postoperative dialysis. Between 2002 and 2010, 5,589 consecutive patients at a single center underwent OPCAB or CABG. 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 10.1, College Station, TX). 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. The mean patient age was 64.9 ± 10.0 years, and there were 4,387 (78.5%) males. Mean preoperative creatinine clearance was 82.0 ± 32.6 mL/min. Perioperative mortality was 1.45% with OPCAB and 1.73% with CABG (P = 0.6). The mean change in creatinine clearance, from preoperative to the lowest postoperative value, was −6.3 ± 14.1 mL/min with OPCAB, versus −5.0 ± 15.5 mL/min with CABG (P = 0.06). In patients with a preoperative creatinine clearance between 30-60 mL/min, the weighted effect of OPCAB on postoperative creatinine change was an additional −1.8 ± 0.9, when compared to CABG (P = 0.04). After matching, OPCAB patients had a greater creatinine rise and greater loss of creatinine clearance postoperatively, compared with CABG patients (both P < 0.05). Requirements for de novo postoperative dialysis were equivalent at 2.6% in OPCAB versus 2.1% in CABG patients (P = 0.4). Median postoperative hospital length of stay was 8 days in both groups (P = 0.8). OPCAB is not associated with better postoperative preservation of creatinine and creatinine clearance when compared to CABG. In fact, patients with moderate renal dysfunction may be more susceptible to a fall in creatinine clearance after OPCAB compared to CABG. These changes in renal indices do not appear, however, to influence clinical outcomes.