Bilateral internal mammary grafts in diabetics: benefits outweigh perioperative risks

Patients with diabetes have more severe coronary disease at presentation and worse overall outcomes than their non-diabetic counterparts, even following surgical revascularisation. Whilst use of the left internal thoracic artery (LITA) is well established and improves event free survival when anastomosed to the LAD, the use of both right and left internal thoracic arteries in bilateral (BITA) grafting is less well described with concerns remaining over the associated increased risks of sternal wound infection, particularly in diabetics.

In this single-centre, retrospective, registry study, patients undergoing BITA grafting between 1996 and 2006 were studied. A total of 69 patients with insulin-treated diabetes and 732 with orally treated diabetes received isolated skeletonised BITA grafts.  Of these patients, 338 were younger than 65 years, 322 were between 65 and 74 years old, and 141 were 75 years or older. Operative mortality was lower than logistic EuroSCORE-calculated mortality (2.9% vs 7%, P < 0.001). Predictors of increased mortality were critical preoperative state (P < 0.001) and age (P = 0.008).

There were 30 cases of sternal infection (3.7%); predictors were re-operation (P <0.001), peripheral vascular disease (P = 0.009), obesity (P = 0.012), chronic lung disease (P = 0.009), and female sex (P = 0.02). Although numbers were small, type 1 diabetics were also disproportionately prone to wound infection (7.2% in type 1 vs 3.2% in type II). Mean follow-up was 8.4 ± 4 years. Kaplan-Meier 10-year survivals were 75%, 59%, and 39% for patients younger than 65, 65 to 74, and at least 75 years, respectively (P <0.001). These were better than corresponding Charlson comorbidity index-predicted survivals (36%, 10%, and 3%, respectively; P <0.001). Off-pump surgery was independently associated with better long-term survival (P = 0.003).

Conclusions:

BITA grafts are safe in patients with diabetes. Favourable short- and long-term outcomes outweigh increased sternal infection risk.

  • Hemo E, Mohr R, Uretzky G, Katz G, Popovits N, Pevni D and Medalion B. Long-term outcomes of patients with diabetes receiving bilateral internal thoracic artery grafts. J Thorac Cardiovasc Surg. 2013 Sep;146(3):586-92.