**2. LIMA use in CABG**

The LIMA is widely considered to be the best conduit for CABG procedures. In a study of the Society of Thoracic Surgeons National Cardiac Database performed by Tabata *et al.*, data from 541,368 CABG surgeries taking place between 2002 and 2005 were analyzed. Among all

© 2013 Maddock et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

procedures performed, 92.4% of patients had at least one IMA graft, and the frequency of LIMA usage by each hospital ranged from 48.0% to 100% with a median of 94% [3]. The presence of an IMA graft has also been identified as an independent predictor of survival and confers significantly better long-term survival rates than the use of saphenous vein grafts alone [2].

received a single internal mammary artery (LIMA) grafted to the LAD with saphenous vein grafts. These arterial revascularization strategies were also seen to convey significantly better cardiac event-free survival rates to elderly (> 75 years) patients as well. The study did not find any significant differences in survival based on the choice of either the RIMA or the radial

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In the longest reported retrospective analysis of CABG procedures, ranging from 6 weeks to 32 years of follow up, Kurlansky *et al.* conducted a review of 4,584 isolated CABG procedures between 1972 and 1994. When patient differences were accounted for and comparisons made between 2,197 matched patients, survival was 16.5% for SIMA patients and 28.5% for BIMA patients after 25 years (p = 0.001). The median survival for SIMA patients was 11.8 years compared to 15.9 years for BIMA patients. There were no significant differences between the two groups in the rates of non-fatal myocardial infarction, reoperation, percutaneous coronary intervention, permanent stroke, or composite freedom from late adverse cardiac events. [12

The location of the distal anastomosis of the RIMA graft also does not appear to significantly affect clinical outcomes of patients undergoing BIMA grafting. Kurlansky *et al.* performed a propensity-matched study of 2,215 patients undergoing BIMA CABG procedures having the RIMA grafted to either the right coronary system or to the left coronary system. In both the matched and unmatched analyses, there was no significant difference in operative or late mortality between the two groups. The median survival for propensity-matched patients in both groups was 16.1 years (p = 0.671) [13]. In another study by Rankin *et al.* there were no significant differences in long-term outcomes based on grafting territory of BIMA grafts as

Not all studies have found significantly increased survival rates for BIMA use over SIMA use. In a study performed by Dewar *et al.*, there was not a significant difference in the 5 or 7-year survival rates for patients undergoing either unilateral or bilateral IMA grafting with supple‐ mental vein grafts. 5-year survival rates for SIMA and BIMA revascularization for patients less than 60 years of age were 94.4% and 94.8%, respectively (p = not significant). There was also no significant difference in 5-year survival rates for patients over 60 years of age. However, the authors did note that there was a trend in lower rates of angina in the patient group

Patency is the most important determinant in long-term prognosis [7]. Due to the extremely low prevalence of use for the RIMA, there have been few studies evaluating its patency compared to the LIMA. However, the studies that have been performed suggest that the RIMA has similar early and even long-term patency rates as the LIMA, especially when grafted to

Fukui *et al.* reviewed the angiographic records of 705 patients undergoing BIMA CABG procedures. Early angiography and 1-year angiographic results for RIMA patency are good,

long as they are anastomosed to the two largest coronary systems [14].

receiving BIMA grafts less than 60 years of age [15].

**4. Patency of RIMA versus LIMA**

similar coronary territories [17].

artery as the second arterial conduit [11].

While anatomically identical to the LIMA, the RIMA is rarely used in CABG procedures, and is almost always used as part of bilateral internal mammary artery (BIMA) grafts when it is utilized. Despite several studies showing that BIMA use confers significantly improved clinical outcomes [4-6], between 2003 and 2005 the frequency of BIMA use was only 4% [3]. Reasons for not using the RIMA include increased operative time and perceived technical difficulty associated with the harvest, concern for perioperative morbidity and mortality, the possibility of reoperations for bleeding, sternal wound infection, and uncertainty as to whether there is a significant benefit with BIMA grafting [7, 8]
