Impact Of Preoperative Occult Renal Dysfunction On Early And Late Outcomes After Off-pump Coronary Artery Bypass

Objective: Renal dysfunction(RD)was a clear independent risk factor for shortterm and long-term mortality of patients after coronary artery bypass grafting(CABG).Off-pump coronary artery bypass grafting(OPCABG)could avoid plenty of complications of extracorporeal circulation.Occult renal dysfunction(ORD)meant that patients with normal serum creatinine(SCr)levels were accompanied by impaired glomerular filtration function(glomerular filtration rate<60 ml/min /1.73 m2).The short-term and long-term effects of ORD on OPCABG patients were still unclear.This study aimed to observe and explore the effects of ORD on the shortterm and long-term prognosis of OPCABG patients after surgery.Methods: This single-center retrospective cohort study enrolled 1273 patients who underwent OPCABG patients.Excluding 58 patients with preoperative SCr level above 132 mol/L,12 patients with unknown perioperative SCr level and 15 patients with incomplete medical records,1188 patients were included in this study.Clinical data of patients were collected,and Cockcroft-Gault formula was used to estimate creatinine clearance(e Cr Cl),which was the glomerular filtration rate,meanwhile patients were divided into ORD group(e Cr Cl<60 m L /min/1.73m2)and control group(e Cr Cl≥60 m L /min/1.73m2).Acute Kidney injury(AKI)was defined and classified by Kidney Disease: Improving Global Outcomes(KDIGO)criteria.Patients were followed up on outpatient or telephone at 1 month,3 months after discharge,and again every 6 months after that.The short-term end point was all-cause death within 30 days after surgery or during postoperative hospitalization,while the long-term end point was long-term death,including cardiac death and renal death.Multivariate logistics regression was used to analyze the independent risk factors of recent end point events,multivariate Cox proportional risk model was used to analyze and evaluate the impact of each risk factor on the long-term survival of patients,and Kaplan-Meier curve was applied to analyze the cumulative incidence of death events in the two groups.Results: There were 260 patients in ORD group(21.89%)and 928 patients in control group(78.11%).Compared with the control group,patients in ORD group were older and had lower body mass index,body surface area and higher NYHA classification,Euro SCOREII,STS score,in-hospital mortality,incidence of postoperative AKI,peak of postoperative SCr and length of stay,and the differences were statistically significant(P<0.05).Multivariate logistic regression analysis showed that ORD was an independent risk factor for postoperative AKI(odds ratio(OR)=2.492;95% confidence interval(CI)1.509-4.115),and ORD was also an independent risk factor for in-hospital death(OR=2.884;95%CI 1.293-6.432).A multivariate Cox analysis showed that ORD was significantly associated with longterm mortality(hazard ratio(HR)= 2.847,95%CI 1.262-6.425).Kaplan-Meier curve showed that the survival rate of ORD group was significantly worse.The 1-year cumulative survival rates in ORD group and control group were 93.5% and 99.0%,respectively,and the 5-year cumulative survival rates were 81.1% and 95.2%,respectively.Conclusions: ORD was an independent risk factor for postoperative AKI,inhospital death and long-term death in OPCABG patients.