Urine NGAL as a biomarker of kidney damage after on- and off-pump coronary artery bypass graft surgery: a prospective pilot study.

INTRODUCTION Acute kidney injury (AKI) is a relatively frequent complication after coronary artery bypass graft surgery (CABG). We compared the off- and on-pump CABG procedures with respect to changes in renal function as reflected by levels of urine neutrophil gelatinase-associated lipocalin (UrNGAL). METHODS In a prospective design, we studied patients who underwent CABG, off- or on-pump, with respect to changes in glomerular filtration rate (GFR) and UrNGAL pre- and postoperatively. UrNGAL was measured using a chemiluminescent microparticle immunoassay. We recorded patients' demographics, past medical history, cardiac function and laboratory findings. Patients were grouped according to the CABG type. RESULTS Of 72 patients, 31 underwent off-pump and 41 on-pump CABG. The mean age was 65.7 ± 8.1 years and 81.9% were males. Groups were similar with respect to the prevalence of hypertension, diabetes, dyslipidaemia, body mass index, and smoking at entry. No patient experienced acute renal failure and there were no deaths. At both time points, the UrNGAL levels were similar in the two groups. Patients in the on-pump group showed a significant improvement in renal function 48 hours postoperatively compared to baseline (p<0.001). UrNGAL levels decreased significantly 3 hours after surgery in the on-pump group (p=0.001), while they tended to decrease in the off-pump group (p=0.057). The overall change in UrNGAL did not differ significantly between groups. CONCLUSIONS According to the UrNGAL measurements, neither of the two CABG techniques was superior in terms of their effect on postoperative renal function. Renal function significantly improved in the on-pump group while UrNGAL levels decreased after surgery in the same group.