Bilateral Versus Single Internal Thoracic Artery Grafting in Diabetic and Older Patients with Triple Vessel Disease: Analysis of a Multicentre Database

Abstract

Background: Use of bilateral internal thoracic arteries (BITA) is associated with improved long-term survival compared to a single internal thoracic artery (SITA), despite its low penetrance in clinical practice. Such a strategy is arguably less desirable in patients who are older and those who have diabetes, due to a perceived increase in perioperative risk with limited prognostic gain associated with BITA. As such, we sought to examine the prevalence and outcomes of BITA use in this subset of patients. Methods: From 2001 to 2013, 25,900 patients at 28 centres with three-vessel coronary disease underwent primary isolated coronary artery bypass grafting (CABG) using at least a single ITA. BITA use was 12% overall, 15% (n = 2379) in those under 70 years of age (n = 15879) and 6.6% (n = 661) in those over 70 years (n = 10016), p < 0.001. Amongst those with diabetes (n = 7948), BITA use was 7.4% (n = 590). Separate propensity-score matched analyses were conducted for the following subsets: 1) over 70 years of age, 2) under 70 years of age and 3) those with diabetes (treated with either oral agents or insulin). The National Death Index was used to determine survival. Results: In the propensity-score matched analysis comparing single versus bilateral ITA in those over 70 years of age (619 matched pairs), there were comparable rates of sternal infection (1.1% vs. 2.1%, p = 0.26) but a trend towards higher 30-day mortality (SITA: 1.1% vs. BITA: 2.7%, p = 0.064). Survival at 8 years was also comparable (SITA: 74 ± 3.2% vs. BITA: 72 ± 3.1%, p = 0.88). In the analysis amongst patients under 70 (2193 matched pairs), 30-day mortality was similar (SITA: 0.3% vs. BITA: 0.5%, p = 0.48), however BITA patients experienced higher rates of sternal infection (0.8% vs. 1.8%, p = 0.008). Survival at 8 years was nonetheless comparable (SITA: 92 ± 1.3% vs. BITA: 92 ± 0.9%, p = 0.29). Amongst patients with diabetes (564 matched pairs), 30-day mortality was comparable (SITA: 0.9% vs. BITA: 2.0%, p = 0.21), as was sternal infection (2.5% vs. 4.1%, p = 0.18). Survival was similar at 8 years (BITA: 84 ± 2.7% vs. SITA: 78 ± 3.8%, p = 0.47). Conclusions: Use of bilateral internal thoracic arteries remains relatively uncommon, especially in older patients and those with diabetes. It is associated with increased rates of deep sternal infection although early mortality was comparable. Mid-term survival was comparable between patients receiving either single or bilateral internal thoracic artery grafting. As such, the benefit of bilateral ITA grafting may lie only in those with longer life expectancies.