Preoperative Renal Insufficiency, Coronary Artery Bypass Grafting And Long Term Results,

PartⅠ: Impact of Renal Dysfunction on Long Term Survival after Isolated Coronary Arterial Bypass Surgery:How Well does eGFR Perform than Serum CreatinineFrom the Departments of Cardiovascular Surgery,Cardiovascular Institute and Fuwai Hospital Peking Union Medical College and Chineses Academy of Medical Sciences, Beijng 100037,ChinaObjective:Coronary artery bypass graft surgery(CABG) is a successful surgical treatment for the prolongation of life in selected patients with coronary artery disease. There has been considerable information on perioperative morbidity and mortality in patients with poorer renal function after CABG,in which preoperative renal dysfunction has been identified as predictive of postoperative morbidity and mortality.But most previous studies used serum creatinine(SCr) levels as assessment of renal dysfunction. However,the serum creatinine concentration is affected by many factors other than glomerular filtration rate(GFR),such as age,sex,and body size.As a result,serum creatinine is not a sensitive marker in normal persons.Several recent studies suggest that the estimated glomerular filtration rate(eGFR) is a good index for assessment of kidney function.The aim of this study was to compare the eGFR and SCr as risk factors for predicting long-term(5-year) survival of Chinese patients undergoing isolated CABG at our institution.Patients and methodsBetween January 1999 and December 2005,5559 consecutive patients who underwent isolated CABG in our institute were prospectively entered into a database after the local ethics committee approved the study.Preoperative and perioperative variables,which included cardiovascular history and cardiovascular risk factors,as well as follow-up data, were recorded according to prespecified data entry forms.The last single serum creatinine levels inμmol/L were obtained for all patients.These values were converted to mg/dl(divided by a conversion factor 88.4).We estimated GFR using the Cockcroft-Gault formula and Modification of Diet in Renal Disease(MDRD) equation respectively.Renal dysfunction was defined according to guidelines from the National Kidney Foundation.Results:Follow-up was complete(97.6%) in 5485 patients.The mean follow-up was 57.97±24.64 months.Follow-up data were obtained from outpatient medical records in our hospital or through telephone contacts with either patients or referring physicians. There were 74 in-hospital all-cause deaths(1.33%).The patients with moderate-to-severe renal dysfunction(eGFR＜60 ml/min per 1.73 m~2) had a higher rate of postoperative complications.There were 248(4.52%)late all-cause deaths during follow-up.Remarkably,the groups of moderate-to-severe renal dysfunction had higher long-term mortality rates.Analysis of receiver-operating characteristic curves showed that the Cockcroft-Gault formula had a maximal accuracy for predicting in-hospital mortality (area under the curve 0.755 for the Cockcroft-Gault formula;P＜0.001).Multivariate logistic analysis and the Cox's analysis results confirmed eGFR＜60 ml/min per 1.73 m~2 base on the Cockcroft-Gault formula is an independent risk factor for predicting in-hospital and long-term mortality(Odds ratio 4.51 for in-hospital mortality;P＜0.001, Hazard ratio 1.54 for long-term mortality;P=0.003),both formulas were superior to serum creatinine.Conclusions:This study shows that the eGFR＜60 ml/min per 1.73 m~2 is an independent risk factor for predicting in-hospital and long-term mortality of Chinese patients after coronary artery bypass grafting and both Cockcroft and Gault formula and MDRD equation appear to provide better measure of risk assessment than the serum creatinine concentration for predicting mortality in patients undergoing CABG. PartⅡDoes off-pump coronary surgery reduce renal injured in non-dialysis-dependent and mild-to-moderate renal dysfunction patients?Objective:Off-pump was compared with on-pump coronary artery bypass graft surgery to evaluate the impact of cardiopulmonary bypass on the incidence of postoperative renal failure.METHODS:From June 2007 to October 2008,65 patients who had no known pre-existing renal disease and age＞=65 years and eGFR＜90 ml/min per 1.73 m~2 were recruited for the study.Patients were divided into two groups:on-pump CABG group and Off-pump CABG group.The last single serum creatinine levels inμmol/L and cystatin C were obtained for all patients.We estimated GFR using the Cockcroft-Gault formula and Modification of Diet in Renal Disease(MDRD) equation.GFR was determined by using 99mTc-DTPA technique.RESULTS:The clinical characteristics were no difference between two groups. No significant difference in outcome was observed between on-pump CABG group and Off-pump CABG group.GFR was slightly decreased after half a year follow-up.CONCLUSIONS:This study shows that the eGFR＜60 ml/min per 1.73 m~2 is an independent risk factor for predicting in-hospital and long-term mortality of Chinese patients after coronary artery bypass grafting.There is no difference between Off-pump and on pump CABG on the incidence of postoperative acute renal failure.