S. Kong1, M. Peltz1, L. C. Huffman1, P. Bajona1, M. A. Wait1, N. Doolabh1, R. Correa1, W. Ring1, M. Jessen1, J. Pruszynski1 1UT Southwestern Medical Center,Department Of Cardiovascular And Thoracic Surgery,Dallas, TX, USA
Introduction: Diabetic patients undergoing major cardiac procedures represent a large, complex group with high risks for complications during the post-operative period. Specifically, an elevated glycated hemoglobin (HbA1c) level is known to be an important predictor and indicator of morbidity and mortality risks for CABG patients. We seek to test the hypothesis that pre-operative HbA1c levels, along with significant covariates, impact post-operative outcomes following on-pump CABG.
Methods: Data were prospectively collected from 669 consecutive patients undergoing on-pump CABG at a single institution between July 2011 and March 2017. HbA1c was collected prior to undergoing surgery. Clinical variables were collected based on the definitions in the STS Adult Cardiac Surgery Database version 2.81. Multivariable logistic regression models were used to assess the effect of HbA1c on post-operative outcomes such as the receipt of post-operative blood products, surgical site infection, and prolonged ventilation. Similarly, a Cox proportional hazards regression model was used to assess the effect of HbA1c on time to discharge while accounting for the competing risk of operative death prior to discharge [operative mortality was 1.9%]. All models controlled for the effect of confounding variables such as demographics, comorbidities and risk factors, medication usage, and surgical characteristics.
Results: No association between HbA1c and the outcomes of post-operative blood products and prolonged ventilation was found in the analysis. A significant relationship between HbA1c and the occurrence of surgical site infection was detected (OR: 1.19; 95% CI: 1.00-1.41; p = 0.045) while controlling for covariates of race, BMI, illicit drug use, pre-operative pneumonia, prior MI, CPB time, and intra-operative blood products. Additionally, a significant association between HbA1c and time to discharge was detected (HR: 1.06; 95% CI: 1.01-1.11; p = 0.017) while controlling for age, smoking history, CVD, PAD, cardiogenic shock, recent heart failure, pre-operative albumin level, intraoperative blood products, surgical status, and post-operative creatinine level [see table].
Conclusion: These data show that increased HbA1c is associated with an increased incidence of a variety of adverse post-operative outcomes even when controlling for known risk factors. Diabetic patients have a variety of physiologic and metabolic derangements, and the exact mechanism behind this observation is not established. The study also does not include the efficacy of perioperative glucose control in these patients. Further investigation is warranted to define the biologic basis of the adverse outcomes that are observed in patients with poor pre-operative glucose control.
