Abstract
PURPOSE: Occult renal disease (ORD) is a clinical condition in which glomerular filtration rate (GFR) is less than 60 ml/min/1.73 m(2), while serum creatinine is ≤ 1.3 mg/dl. The aim of the study was to compare the incidence of postoperative stage I acute kidney injury (AKI) according to Acute Kidney Injury Network (AKIN) classification in patients with ORD undergoing either off-pump or on-pump coronary artery bypass grafting. METHODS: A single center prospective randomized study was conducted from March 2011 through January 2014. A total of 120 coronary artery disease (CAD) patients with ORD undergoing coronary artery bypass grafting (CABG) were randomized to either off-pump (group1, n = 62) or on-pump (group2, n = 58) CABG in 1:1 ratio by computer-generated random number table. The GFR and serum creatinine levels were measured preoperatively and postoperatively on day 1 and day 5. The primary outcome (postoperative AKI (stage I)) and secondary outcomes (AKI (stage III) requiring renal replacement therapy (RRT) death, myocardial infarction (MI), cerebrovascular accident, atrial fibrillation (AF), and re-exploration for bleeding) at 30 days were analyzed between the groups. RESULTS: There is no significant difference in baseline characteristics of patients between off-pump and on-pump group. The incidence of postoperative AKI (stage I) was similar between on-pump (20.69%) and off-pump (16.13%) groups (p = 0.51). There was no significant difference in mortality (p = 0.33), postoperative MI (p = 0.34), cerebrovascular accident (p = 1.00), re-exploration (p = 0.96), and AF (p = 0.50). The number of patients of stage III AKI requiring RRT was higher in the off-pump group (3 patients, 4.8%) and none in the on-pump group (p = 0.08). CONCLUSIONS: This study demonstrated that on-pump CABG is associated with significantly lower GFR and significantly higher serum creatinine on postoperative day 1 which return to baseline by postoperative day 5. In patients with ORD undergoing CABG, the incidence of postoperative AKI and major adverse cardiac and cerebrovascular events were similar between off-pump or on-pump CABG patients.