Background: Bilateral internal thoracic arteries (BITA) coronary bypass grafting may improve long term outcomes but is associated with increased deep sternal wound infections (DSWI). We analyzed whether BITA skeletonization impacts DSWI and operative mortality (OM) using the Society of Thoracic Surgeons Adult Cardiac Surgery Database (STS-ACSD).

Methods: Primary, isolated, non-emergent/non-salvage BITA patients (July 2017-December 2018) in STS-ACSD were divided into groups based on BITA harvesting technique: both skeletonized (ssBITA), at least one non-skeletonized (Non-ssBITA). DSWI and OM Observed-to-Expected (O/E) ratios were compared using the STS Peri-operative Risk Models. ssBITA versus Non-ssBITA DSWI and OM Adjusted Odds Ratio (AOR) were calculated by multivariable logistic regression and corroborated by propensity score matching.

Results: 11,269 patients (42.8%-ssBITA, 57.2%-Non-ssBITA, 770 hospitals, 1,448 surgeons) were analyzed. The ssBITA group had a higher incidence of comorbidities and off-pump surgery. Overall incidence of DSWI and OM was 0.98%(O/E-5.1) and 1.72%(O/E-1.4), respectively and was 28%(p=0.129) and 23%(p=0.096) lower in ssBITA. The DSWI O/E was highest (5.9) in Non-ssBITA and lowest in ss-BITA (4.1). After multivariable adjustment, ssBITA was associated with a decreased risk of DSWI [AOR(95%CI)=0.66(0.44-1.00),p=0.05], with no difference in OM. These results were confirmed among 3884 propensity score matched pairs. DSWI increased sharply with increasing number of risk factors for DSWI regardless of harvesting technique with a trend for higher DSWI among Non-ssBITA for all risk categories.

Conclusions: The observed high O/E indicates that BITA grafting is associated with increased risk of DSWI. Risk adjusted DSWI rate and lower O/E in ssBITA support protective role of skeletonization.