**5. Myocardial infarction, cerebrovascular accidents, freedom from reoperation, and quality of life**

Stevens *et al.* report that patients undergoing BIMA CABG operations had significantly better long-term freedom from myocardial infarction (MI) and from coronary reoperation. After 10 post-operative years, 85% of BIMA patients were free of myocardial infarction compared to 82% of patients receiving LIMA grafts (p = 0.001). 99% of BIMA patients also were free from coronary reoperation compared to 98% of LIMA patients (p = 0.01) [4].

While Burfeind *et al.* found no significant difference in 15-year mortality rates for pa‐ tients receiving single IMA grafts or multiple (bilateral) IMA grafts, they did find signifi‐ cant differences in the rates of MI and CABG reoperation. However, these rates differ based on the definition of what constitutes a patient receiving multiple IMA grafts. In their study 1,067 patients that had undergone isolated CABG procedures were analyzed by three different methods. In the first analysis (analysis I), patients were analyzed based on the initial surgical strategy for revascularization – SIMA or BIMA grafts. However, not all patients who were designated to receive BIMA grafts were able to be revascular‐ ized with multiple IMAs, and likewise some patients designated to receive SIMA grafts ultimately received BIMA grafts. Analyses II and III were therefore performed based on the surgery the patient ultimately received and not the initial surgical strategy. Analysis II defined "multiple IMA grafts" based on the number of distal anastomoses performed. Therefore, in analysis II, multiple coronary systems anastomosed with multiple IMA grafts were considered "multiple IMA grafts" as well as a single coronary system se‐ quentially anastomosed with a single IMA graft. In analysis III only multiple coronary systems anastomosed with multiple IMA grafts were considered to be "multiple IMA grafts." In both analyses II and III, Burfeind *et al.* found that there were significantly re‐ duced rates of CABG reoperation in patients receiving multiple IMA grafts when com‐ pared to patients only receiving a single IMA graft (analysis II: 9.7% reop SIMA, 4.5% BIMA p = 0.0095; analysis III: 9.7% reop SIMA, 3.4% BIMA, p = 0.0026). However, in analysis III there was also a significantly reduced rate of MI in BIMA patients when com‐ pared with SIMA patients (17.4% versus 11.6% for SIMA and BIMA patients, respective‐ ly, p = 0.0181) [6].

with an overall patency of 98.8% at early angiography and 94.3% at 1-year postoperative follow-up compared to 99.1% and 97.0% for the LIMA at the same follow-up times (p = 0.7732 and p = 0.1288, respectively). In terms of grafting technique, at both early and 1-year angio‐ graphic follow up, there were no significant differences in the patencies of *in situ* versus free RIMA grafts. For free RIMA grafts, there were also no significant differences in patency rates between sites of proximal anastomoses (composite versus aorta). However, for the *in situ* RIMA, patency rates were significantly better when anastomosed to the anterior coronary

Tatoulis *et al.* evaluated the results of 991 consecutive RIMA postoperative CABG angiograms taking place between 1986 and 2008. The main focus was graft patency, with grafts considered non-patent if they had a greater than 80% stenosis, string sign, or total occlusion. When com‐ pared to the LIMA for identical grafting territories, there was no significant difference in RIMA and LIMA patency. For the LAD, overall LIMA patency was 96.9% while overall RIMA patency was 94.6% (p = 0.74). When grafted to the circumflex, LIMA patency was 90.7% versus RIMA pa‐ tency of 91.9% (p = 0.85). Long-term patency results for the RIMA were favorable as well, with 92% of 352 RIMA grafts in place for greater than 10 years being patent. RIMA patencies were al‐ ways better than radial artery or saphenous vein graft patencies. At 15 years, RIMA patency was 79% compared to 50.7% for saphenous vein grafts (p < 0.001). 15-year data were not available for the radial artery; 10-year patency was 78% (p < 0.01 when compared to RIMA 10-year patency).

There are a variety of grafting techniques for BIMA, such as *in situ* grafting versus Y/T-grafts that may have an impact on patency rates. In a study by Glineur *et al*., 304 patients receiving BIMA grafts were randomized to receive either an *in situ* RIMA graft or a Y-graft with the RIMA anastomosed proximally to the *in situ* LIMA as an end-to-side graft. Follow-up angiog‐ raphy was performed at 6 months and the RIMA patency rate in both groups was 97% (p = 0.99) [18]. In a similar but slightly larger study, Calafiore *et al.* also found no significant differences in patency rates between *in situ* and Y-graft RIMA grafts at both early (13 days) and long-term (17 months) angiographic follow up [19]. A longer study by Hwang *et al.* studied 5-year angiographic patency results of BIMA grafting configurations. At 1 year of follow-up, *in situ* RIMA patency rates were not significantly different than Y-graft RIMA patency rates (92.5% versus 95.7%, respectively, p = 0.138). Similarly at 5 years of follow up, there were also no significant differences in patency rates (92.5% *in situ* versus 92.4% Y-graft, p = 0.978) [20].

**5. Myocardial infarction, cerebrovascular accidents, freedom from**

coronary reoperation compared to 98% of LIMA patients (p = 0.01) [4].

Stevens *et al.* report that patients undergoing BIMA CABG operations had significantly better long-term freedom from myocardial infarction (MI) and from coronary reoperation. After 10 post-operative years, 85% of BIMA patients were free of myocardial infarction compared to 82% of patients receiving LIMA grafts (p = 0.001). 99% of BIMA patients also were free from

**reoperation, and quality of life**

territory when compared to other grafting methods (p < 0.0001)[16].

122 Artery Bypass

However, the authors noted that data for radial artery patency is limited [17].

In their original retrospective study on BIMA versus SIMA grafting in elective CABG patients, Lytle *et al.* also found that patients receiving BIMA grafts had significantly greater reoperationfree survival rates after 12 post-operative years than patients receiving only SIMA grafts with or without any additional vein grafts. BIMA patients had a reoperation-free survival of 76.8% compared to the 62.4% reoperation-free survival rate of SIMA patients [9].

As previously mentioned, Nasso *et al.* found that patients receiving two arterial grafts had significantly better long-term, cardiac-event free survival outcomes than patients who just received a single arterial graft with or without additional saphenous vein grafts. As expected, adverse cardiac events occurred significantly less frequently in the groups receiving two arterial grafts versus the group receiving just one. There was no significant difference in the occurrence of adverse cardiac events between the three groups receiving two arterial grafts. Cerebrovascular complications occurred more frequently in the SIMA group, however this difference was not significant. The authors note that this increased incidence of cerebrovas‐ cular complications may be due to the more extensive manipulation of the ascending aorta needed in the SIMA group due to the greater number of proximal anastomoses [11].

Damgaard *et al.* performed a study to assess the health-related quality of life improvements in patients undergoing traditional CABG procedures versus patients undergoing TAR CABG procedures. 331 patients were randomized between the two revascularization techniques and over 90% of patients responded to the questionnaire at the specified time points. Preopera‐ tively, patient scores in all areas of the questionnaire were significantly lower than that of the results of the standardized Danish population. Post-operatively, both revascularization groups showed significant improvement in all areas at 3 months and 11 months, with the TAR group showing improvement in the 'social functioning' category that was significantly higher than the conventional revascularization group. There was no significant difference in postoperative improvement in the categories 'physical component summary,' 'bodily pain,' and 'vitality' between the two revascularization groups [21].

could still be considered a risk factor for SWI, the risk is not increased by receiving BIMA

Total Arterial Revascularization in Coronary Artery Bypass Grafting Surgery

http://dx.doi.org/10.5772/54866

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One of the probable factors contributing to the low prevalence of BIMA use is the perceived increased operative time required to harvest both IMAs [7]. However, few studies have actually included operative time in their statistical analyses, most simply report aortic crossclamp and cardiopulmonary bypass times. Gansera *et al.* do report total operative time and found that operative time was significantly increased for patients receiving BIMA grafting compared to patients receiving SIMA grafting (189 minutes versus 164 minutes, respectively, p = 0.00). However, the number of anastomoses in the BIMA group was significantly higher than in the SIMA group (3.8 versus 3.1, respectively, p = 0.00), which could in part explain the

The success of the LIMA in CABG procedures has lead surgeons to search for other arterial conduits. The radial artery has become a popular choice as an additional arterial conduit in attempts to achieve total arterial revascularization of the myocardium. There are numerous advantages to using the radial artery, including its long length, exposure to systemic blood pressures, and the fact that it is seldomly affected by atherosclerosis. However, the radial artery has a thicker tunica media, which is thought to contribute to its greater vasoconstrictor response than the IMA and could possibly lead to vessel occlusion. Thus, care must be taken during operative harvesting and the use of calcium-channel blockers may ameliorate a

Like the LIMA, the radial artery has been shown to have significantly better short and longterm patency results and outcomes than vein grafts. In the radial artery patency study (RAPS), Desai *et al*. randomized 561 patients to receive a radial artery graft to either the inferior (right) coronary territory or to the lateral (circumflex) coronary territory, with a saphenous vein graft anastomosed to the opposite territory in each group as a control. All patients also received a LIMA graft to the LAD, with the main endpoint of the study being 1-year angiographic complete occlusion of the radial artery versus saphenous vein. In this definition of occlusion, grafts displaying the string-sign would be considered patent. At the mean follow-up of 10.9 months, 13.6% of saphenous vein grafts were completely occluded and 8.6% of radial artery grafts were completely occluded (p = 0.009). The authors also found that the patency of radial artery grafts depends on the severity of the native vessel stenosis, with better patency results corresponding with higher grades of stenosis. Thus, the authors recommend using the radial

In a follow-up to the original RAPS study, Deb *et al.* extended the mean angiographic followup time to 7.7 years, with 269 patients of the original 561 undergoing late angiography. The primary endpoint was functional graft occlusion; vessels displaying narrowing or reduced flow were considered occluded as well as vessels that were completely occluded. 12.0% of radial artery grafts were determined to be functionally occluded compared with 19.7% of

artery for the most highly occluded coronary vessel after the LAD [25].

grafting [12].

increased operative time observed [8].

vasospastic response [24].

**7. Radial artery grafts as a second arterial conduit**
