Perioperative n-acetylcysteine to prevent renal dysfunction in high-risk patients undergoing CABG surgery - A randomized controlled trial

Context Renal dysfunction is a complication of coronary artery bypass graft (CABG) surgery performed with cardiopulmonary bypass (CPB) that is associated with increased morbidity and mortality. N-acetylcysteine, an antioxidant and vasodilator, counteracts renal ischemia and hypoxia. Objective To determine whether perioperative intravenous (IV) N-acetylcysteine preserves renal function in high-risk patients undergoing CABG surgery with CPB compared with placebo. Design, Setting, and Patients Randomized, quadruple blind, placebo-controlled trial (October 2003-September 2004) in operating rooms and general intensive care units (ICUs) of 2 Ontario tertiary care centers. The 295 patients required elective or urgent CABG and had at least 1 of the following: preexisting renal dysfunction, at least 70 years old, diabetes mellitus, impaired left ventricular function, or undergoing concomitant valve or redo surgery Interventions Patients received 4 (2 intraoperative and 2 postoperative) doses of IV N-acetylcysteine (600 mg) (n = 148) or placebo (n = 147) over 24 hours. Main Outcome Measures The primary outcome was the proportion of patients developing postoperative renal dysfunction, defined by an increase in serum creatinine level greater than 0.5 mg/dL (44 mu mol/L) or a 25% increase from baseline within the first 5 postoperative days. Secondary outcomes included postoperative interventions and complications, the requirement for renal replacement therapy (RRT), adverse events, hospital mortality, and ICU and hospital length of stay. Results There was no difference in the proportion of patients with postoperative renal dysfunction (29.7% vs 29.0%, P=.89; relative risk [RR], 1.03 [95% confidence interval {CI}, 0.72-1.46]) in the N-acetylcysteine and placebo groups, respectively. We noted nonsignificant differences in postoperative interventions and complications, the need for RRT (0.7% vs 2.1 %; P=37), total (6.1% vs 9.6%; P=.26) and serious adverse events, hospital mortality (3.4% vs 2.7%; P>39), and ICU and hospital length of stay between the N-acetylcysteine and placebo groups. A post hoc subgroup analysis of patients (baseline creatinine level >1.4 mg/dL [120 mu mol/L]) showed a nonsignificant trend toward fewer patients experiencing postoperative renal dysfunction in the N-acetylcysteine group compared with the placebo group (25.0% vs 37.1 %; P=.29). Conclusions N-acetylcysteine did not prevent postoperative renal dysfunction, interventions, complications, or mortality in high-risk patients undergoing CABG surgery with CPB. Further research is required to identify CABG patients at risk for postoperative renal events, valid markers of renal dysfunction, and to establish renal thresholds associated with important clinical outcomes.