Preoperative hemoglobin A1c levels and increased risk of adverse limb events in diabetic patients undergoing infrainguinal lower extremity bypass surgery in the Vascular Quality Initiative

Background: The impact of preoperative glycemic control on the risk of adverse perioperative outcomes in diabetic patients undergoing lower extremity bypass (LEB) surgery is not well-understood. We determined whether higher preoperative hemoglobin A1c (HbA1c) levels are associated with an increased risk of major adverse limb events, major adverse cardiovascular events, and mortality in diabetic patients undergoing infrainguinal LEB. Methods: A retrospective review of all infrainguinal LEB surgeries in the Vascular Quality Initiative registry from January 2012 to February 2017 was performed. Only surgeries performed on diabetic patients with complete demographic and clinical data, including HbA1c value at the time of LEB, were included for analysis (n = 7727). Entries were stratified according to the following HbA1c levels: 6 or less (n = 1087), greater than 6 to 7 or less (n = 2137), greater than 7 to 8 or less (n = 1657), and greater than 8 (n = 2846). Multivariate logistic regression was used to determine the association of preoperative HbA1c levels on the risk of in-hospital major adverse limb events (above ankle amputation, loss of primary graft patency), major adverse cardiovascular events (myocardial infarction, stroke, congestive heart failure, cardiac arrhythmia), and mortality. Results: The number of surgeries complicated by adverse limb and cardiovascular events were 356 (4.6%) and 1314 (17.0%), respectively. There were 72 in-hospital deaths (0.9%). After adjustment for clinical and demographic variables, patients with high HbA1c values (>= 8%) were at an increased risk of adverse limb events (odds ratio [OR], 1.37; 95% confidence interval [CI], 1.01-1.86) compared with those with a normal HbA1c (>6% to <= 7%). High HbA1c values were not associated with an increased risk of cardiovascular events (OR, 1.07; 95% CI, 0.81-1.43) or mortality (OR, 1.57; 95% CI, 0.83-3.03). Patients with low HbA1c values (<= 6%) did not experience a significantly higher risk for any of the three outcomes. In a stratified analysis, the association of high HbA1c values with adverse limb events was only present in those presenting without critical limb ischemia (OR 1.82; 95% CI, 1.05-3.16). Conclusions: Poor preoperative glycemic control in diabetic individuals undergoing infrainguinal LEB, particularly in those without critical limb ischemia, is associated with an increased risk of in-hospital limb events. Further study should evaluate whether improved efforts to identify individuals with poorly controlled diabetes and subsequent interventions to better optimize glycemic control during the preoperative period improve limb outcomes after LEB.