Preoperative Glycaemic Control and Severity of Sternal Wound Infections After Cardiac Surgery: Association of Elevated HbA1c with Deep Versus Superficial Infections

​ Background Sternal wound infections, including superficial and deep sternal wound infections, are complications after CABG and other cardiac surgeries. Elevated preoperative HbA1c, suggesting poor glycemic control, impairs wound healing and may escalate postoperative risk. This study evaluates the association between preoperative HbA1c levels and the anatomical severity (superficial versus deep) of sternal wound infections among patients who develop postoperative wound complications.   Methods A 24-month retrospective observational study was conducted at a tertiary care cardiac surgery center. Adult patients (≥18 years) going through elective or urgent isolated cardiac surgery with a preoperative HbA1c measured within 30 days were included. Using consecutive sampling, 133 patients who developed sternal wound infections were identified. DSWI and SSWI were defined according to CDC criteria, and logistic regression was employed to evaluate the association between HbA1c categories and the odds of presenting with deep (DSWI) rather than superficial (SSWI) sternal wound infections.   Results Among 133 sternal infections, 69.9% were DSWI and 30.1% SSWI. Diabetic-range HbA1c was common (62.4%) and was associated with a higher proportion of DSWI, occurring in 94% of diabetic-range patients versus 26.5% in normal and 37.5% in pre-diabetic groups (). Univariable logistic regression demonstrated that among patients who developed a wound infection, those with a diabetic-range HbA1c had significantly higher odds of the infection involving deep tissues rather than remaining superficial (OR 43.33; 95% CI 14.35–156.95; p < 0.001).   Conclusion Among patients who develop postoperative sternal wound infections, an elevated preoperative HbA1c is strongly associated with deep rather than superficial infection involvement. While this case-only design cannot establish the absolute risk of infection development, preoperative HbA1c serves as a valuable indicator of potential anatomical severity within an infected cohort. Rather than mandating clinical delays, routine preoperative HbA1c assessment should be utilized as a non-invasive risk-stratification tool to identify patients who may benefit from closer perioperative metabolic optimization and extended postoperative surveillance