Preoperative angiotensin-converting enzyme inhibitors and acute kidney injury after coronary artery bypass grafting

Background. Angiotensin-converting enzyme (ACE) inhibitors confer renal protection in different clinical settings. No final conclusions are available on the renal benefits of ACE inhibitors after coronary artery bypass grafting (CABG). Because ACE inhibitors decrease glomerular perfusion pressure, they may exacerbate kidney injury during cardiopulmonary bypass (CPB)-related hypoperfusion. We evaluated the effect of preoperative ACE inhibitors on acute kidney injury (AKI) after CABG. Methods. A propensity score-based analysis of 536 patients undergoing CABG on CPB was performed, among which 281 received ACE inhibitors preoperatively. Patients with preoperative end-stage renal failure requiring dialysis were excluded. Postoperative AKI was defined as 50% or more decrease in the glomerular filtration rate from preoperative or postoperative mechanical renal support. Results. After CABG, AKI developed in 49 patients (9.1%), and 23 (4.2%) required dialysis. The incidence of AKI was 6.4% in patients who received preoperative ACE inhibitors and 12.2% in patients who did not (p = 0.02). The incidence of AKI requiring dialysis was 2.4% in the treatment group and 6.3% in controls (p = 0.03). After adjusting for propensity score and covariates, preoperative ACE inhibitors were found to reduce the incidence of postoperative AKI (odds ratio, 0.48; 95% confidence interval, 0.23 to 0.77; p = 0.04). Other independent predictors were age, preoperative glomerular filtration rate, left ventricular ejection fraction of less than 0.35, preoperative use of intraaortic balloon pump, emergency operation, and CPB time. Conclusions. Preoperative ACE inhibitors are associated with a reduced rate of AKI after on-pump CABG surgery.