Chronic Kidney Disease is Associated with Poor Outcomes after Isolated Coronary Artery Bypass Grafting

Purpose: To examine the effect of different stages of chronic kidney disease (CKD) on the postoperative mortality and complications after isolated coronary artery bypass grafting (CABG), using a large cohort from the Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) database. Methods: Data from 31,250 patients who underwent CABG between 2001 and 2011 was analysed. Following calculation of the preoperative glomerular filtration rate (eGFR) patients were classified into 5 stages of CKD: normal (eGFR > 90 ml/min/1.73m2), mild renal impairment (eGFR 60 to 89), moderate (eGFR 30 to 59), severe (eGFR < 30 ml/min/1.73m2) and dialysis dependent. The relationship between the stage and outcomes was analysed by univariate regression, and then by multivariable logistic and Cox regression using the known risk factors in the AusScore II model, a predictive model of 30-day mortality developed from the same database. Results: Almost 77% of isolated CABG cases had some degree ofCKD- mild 50.3%, moderate 22.7%, severe 2.3%, and dialysis-dependent 1.5%. Compared to patients with normal eGFR, the adjusted risk for 30-day mortality increased with stage of CKD from mild (1.8 fold, 95% CI: 1.3-2.6) to dialysis dependent (4.4 fold, 95% CI: 2.4-8.2). The return to OR, prolonged ventilation, prolonged hospital stay, sepsis and need for transfusion were all increased with the stage of CKD. Late survival also decreased with CKD stage, from 10-year survival of85%in normaleGFRto 45.5% for severeCKD.Patients on dialysis had a better outcome on some measures than those with severe CKD without dialysis. Conclusions: Poor kidney function was a strong independent predictor for 30-day mortality and for many postoperative complications. In addition, late survival was significantly reduced. The high frequency of CKD means that these findings should be considered in all discussions and decisions regarding CABG surgery.