Relationship Between Diabetic Variables and Outcomes After Coronary Artery Bypass Grafting in Diabetic Patients

• Published in: Heart, lung & circulation lung & circulation, 2017-04, Vol.26 (4), p.371-375
• Main Authors: Wang, Tom Kai Ming, MBCHB, Woodhead, Andrew, MBCHB, Ramanathan, Tharumenthiran, FRACS, Pemberton, James, MRCP
• Format: Article
• Language: English
• Subjects: Aged; Blood Glucose - metabolism; Cardiac surgery; Cardiovascular; Coronary Artery Bypass; Coronary artery bypass grafting; Diabetes mellitus; Diabetes Mellitus, Type 2 - blood; Diabetes Mellitus, Type 2 - mortality; Female; Glycated Hemoglobin A - metabolism; Humans; Male; Middle Aged; Predictive Value of Tests
• ISSN: 1443-9506; 1444-2892
• DOI: 10.1016/j.hlc.2016.05.117

Background Nearly half of the patients undergoing coronary artery bypass grafting (CABG) have diabetes. There is mixed data as to whether preoperative (haemoglobin A1c{HbA1c}) and/or perioperative diabetes control is associated with mortality and morbidity after CABG. We reviewed the characteristics and outcomes of diabetic patients undergoing CABG with a focus on HbA1c, perioperative glucose levels and diabetic treatment regimens. Methods Diabetic patients undergoing CABG during July 2010 to June 2012 were studied (n=306). The last preoperative HbA1c levels, and perioperative glucose levels (mean and coefficient of variation {CV}) were retrospectively recorded, as well as the pre-existing and perioperative diabetes treatment regimens for analyses. Results Mean HbA1c was 7.7+/-1.6%, and 11.1% (34), 56.2% (172), and 32.7% (100) of patients were managed preoperatively with diet only, oral diabetic medications and insulin respectively. For operative mortality which occurred in 2.0%, C-statistics (95% confidence interval) was only significant for HbA1c, 0.855 (0.757-0.975), and glucose CV on the day of surgery, 0.722 (0.567-0.877). HbA1c also detected postoperative renal failure, C-statistic 0.617 (0.504-0.730), but not other complications or mortality during follow-up. In multivariate analysis, HbA1c was the only diabetes-related independent predictor of operative mortality, hazards ratio 4.13 (1.04-16.4), and none of the diabetes-related variables predicted mortality during follow-up or other postoperative complications. Conclusion Preoperative HbA1c was the only diabetic variable to independently predict operative mortality after CABG, suggesting medium-term preoperative diabetes control is more important and prognostic of operative outcomes than perioperative diabetes control.