Bilateral Internal Thoracic Artery Graft in Coronary Artery Bypass Grafting

Abstract

Percutaneous coronary intervention (PCI) is the first choice for treating simple coronary artery lesions because of the progress of coronary stent techniques in recent years. However, cases involving multivessel coronary artery disease are generally treated with coronary artery bypass grafting (CABG). Several recent studies have demonstrated that the long-term outcomes of CABG are superior to those of PCI in patients with multivessel and/or left main disease 1 -. In Japanese guidelines on revascularization for stable coronary artery disease, which were revised in 2018, CABG is considered a class I recommendation for all types of stenosis location except for “one vessel disease without proximal LAD stenosis” . CABG remains the superior method for treating selected patient groups. Saphenous vein graft (SVG) is the most popular graft used in CABG. A survey of the Japanese Association for Coronary Artery Surgery demonstrated that SVG is used more than 40% inpatients undergoing CABG . However, SVG shows poor patency rates and does not improve long-term morbidity . Conversely, the left internal thoracic artery (ITA) has superior graft patency and excellent clinical results . Several trials reported a 10-year patency of the left ITA of 90%–95% compared with 50% in SVG 13, . The use of arterial conduits in CABG has been hypothesized to improve long-term results . Therefore, some arterial grafts have been used as bypass grafts including the right ITA , radial artery 17) and right gastroepiploic artery . Various combinations of these arterial grafts have been employed (Fig. 1) and many retrospective studies have supported their safety and effectiveness. These findings suggest that arterial grafts are better suited for coronary bypass grafts than venous grafts. Among the arterial grafts used for CABG, ITA has the greatest long-term patency rate. Many factors regarding resistance to the development of atherosclerosis in ITA have been indicated by numerous studies: structurally, its endothelial layer shows fewer fenestrations, lower intercellular junction permeability, greater antithrombotic molecules such as heparin sulfate and tissue plasminogen activator and higher endothelial nitric oxide production. These are some of the unique ways that make the ITA impervious to the transfer of lipoproteins, which are responsible for atherosclerosis development 19 -. In comparison, the radial artery has a relatively thick media and a tendency for distal intimal hyperplasia . Therefore, the use of bilateral ITA graft is theoretically reasonable for CABG in terms of long-term patency and survival. Numerous observational studies and metaanalyses have demonstrated the superiority of bilateral ITA in terms of survival compared with single ITA. Current guidelines therefore recommend bilateral ITA for CABG as class IIa 9, . In this review, the advantages and disadvantages of using bilateral ITA in CABG are discussed. Moreover, the only randomized trial comparing bilateral and single ITA to date is reviewed.