Does off-pump coronary surgery reduce postoperative acute renal failure? The importance of preoperative renal function.

BACKGROUND: Off-pump was compared with on-pump coronary artery bypass graft surgery to evaluate the impact of cardiopulmonary bypass on the incidence of postoperative acute renal failure (ARF).

METHODS: From November 1994 to December 2001, 2,943 patients having multivessel surgical disease underwent myocardial revascularization. Ninety patients were excluded because of incompleteness of data, intraoperative death, or preoperative chronic dialysis. The analysis was split: one analysis included 1,724 (862 each group) of 2,618 patients with normal preoperative creatinine (<1.5 mg/dL), and the second analysis included 160 (80 each group) of 215 patients with preoperative abnormal renal function; in both analyses matched groups were selected applying propensity score.

RESULTS: In the group with normal preoperative creatinine, the incidence of 30-day ARF was 5.4% (2.9% off-pump versus 7.9% on-pump; p < 0.001). Stepwise logistic regression confirmed that cardiopulmonary bypass was an independent variable for increased postoperative ARF incidence (odds ratio, 3.3), as well as age and reduced left ventricular ejection fraction. Receiver operating characteristic curves showed that cardiopulmonary bypass duration was a predictor of higher ARF incidence (area under the curve, 0.79) with a cutoff value of 66 minutes. In the patients with abnormal renal function preoperatively, the incidence of ARF was similar between the groups (16.3% on-pump versus 12.5% off-pump; p = 0.499). Acute renal failure had an important impact on early (odds ratio, 3.6) and late mortality (hazard ratio, 4.1).

CONCLUSIONS: Off-pump surgery plays an important renoprotective role and provides better early and late outcome in patients with normal preoperative creatinine. When the preoperative creatinine is abnormal, the surgical strategy does not seem to have any influence. The occurrence of ARF significantly impairs early and long-term mortality, and the surgical strategy does not improve outcomes.