**5. General advantages of arterial grafting**

Several advantages to arterial grafting have been demonstrated relative to CABG without arterial grafts. Most notably, the LIMA-LAD graft has been shown to be an independent predictor of survival after CABG when compared with patients not receiving LIMA-LAD [76]. In addition, using more than one IMA graft reduces the need for subsequent reintervention and prolongs survival relative to patients receiving only one arterial grafts

Conduit Selection for Improved Outcomes in Coronary Artery Bypass Surgery 149

Fig. 1. Effects of completeness of revascularization on 12-year old Kaplan-Meier survival in triple-vessel disease (3-Ves Dis) patients. (Left) All-arterial patients. (Right) Internal thoracic artery/saphenous vein (ITA/Vein) patients. Incomplete - completeness of revascularization index (CRI) less than 1, or 2 grafts; complete CRI equal to 1, or 3 grafts; complete plus - CRI greater than 1, or 4 or more grafts. All p values by log-rannk (Mantel-Cox) test. (CABG -

may be related to its unique freedom from arteriosclerosis and due to the rich run-off bed provided by the LAD coronary and its branches [85]. Since there is no basis for suggesting or concluding that the biological and mechanical properties of the right IMA are different from the LIMA, successes with the LIMA have prompted investigation of the potential

The original description of BIMA for CABG is credited to Kay in 1969 [86]. Since then, multiple centers including our own have investigated the impact of BIMA grafting on longterm results of CABG. Advantages of BIMA have been somewhat difficult to prove definitively without randomized controlled trials in this area, which have not been conducted secondary to cost concerns and administrative requirements associated with studies inherently requiring significant longitudinal follow-up [87]. Instead, investigation and documentation of BIMA benefits have relied on evaluating institutionally maintained observational databases to show differences between the "treatment group" and the "control group" by way of propensity matching [87]. Analysis of these data show improved long-term results for patients receiving BIMA grafting as compared with single IMA grafting. However, survival curves do not separate until several years postoperatively, which has been a consistent finding [15, 88, 89; Figure]. The demonstrated clinical advantages of BIMA grafting strategies include prolonged survival and reduced need for coronary reintervention on the basis of recurrent myocardial ischemia, including freedom from the need for coronary reintervention [15, 88, 90] which hold true for women as well as for men, where it has been demonstrated that use of BIMA had 3-fold improved cardiac-

related survival compared with patients who did not receive an IMA graft [91].

Reported rates of BIMA use in CABG range from 4.0% to nearly 50% depending upon several factors including the contributing authors' practice preferences and the particular patient cohort treated [19-22, 92]. However, it has been estimated that up to 80% would be candidates for BIMA grafting [93]. Subjective and potential obstacles to BIMA use include increased surgical times, increased technical challenges, especially related to the positioning

coronary artery bypass graft surgery.)

benefits of bilateral IMA (BIMA) grafting.

[15, 17]. Similarly, Guru et al evaluated the potential benefit of multiple arterial grafting in over 53,000 patients undergoing primary CABG between 1991 and 2001. After propensity matching, patients receiving 2 arterial grafts had decreased rates of cardiac readmission and reduced incidence of the composite of cardiac readmission, death, and repeat revascularization relative to those with one arterial grafts [23]. Furthermore, patients receiving 2 arterial grafts had improved survival compared with patients receiving only one arterial graft [23]. Similar findings were reported by Nasso, et al, who found no differences at 2 years between groups receiving RA, in-situ RIMA, or free RIMA as the 2nd arterial graft, although each of these groups was superior to patients receiving only one arterial graft (LIMA-LAD) with respect to cardiac event-free survival [77]. Zacharias et al also demonstrated advantages of RA grafting as a 2nd arterial conduit on long-term survival when compared to RSVG conduits [14].

In addition, multiple arterial grafts and their arrangements in all coronary distributions have been proven superior to venous grafts with regard to long term patency regardless of the anatomic details of the native coronary and distal anastomosis [55]. These results are particularly applicable in the context of recurrent angina [16, 55, 78]. Finally, perhaps one of the best recent demonstrations of the advantages of arterial grafting over RSVG conduits was provided by Gaudino et al, who studied 60 CAD patients who had previously undergone PCI and developed in-stent restenosis. After undergoing CABG, patients receiving IMA and RA grafts had patency rates of 90% while those undergoing RSVG had patency rates of 50% at a mean follow-up of 52 months [79].

### **5.1 Total arterial revascularization**

Since SVG conduits inevitably fail, particularly late [62], there has been increased enthusiasm for total arterial revascularization for CABG. Total arterial revascularization may obviate the concerns of vein graft failure and has been shown to have good shortterm results [80]. However, little evidence is available to suggest that outcomes are improved with "all-arterial" grafting [81]. Zacharias et al have recently demonstrated that patients with multi-vessel CAD undergoing all-arterial grafting had improved 12-year survival compared with matched patients who underwent standard CABG with LIMA-LAD and RSVG to other distal targets [82]. Furthermore, complete coronary revascularization and use of all-arterial grafting strategy was associated with improved 12-year survival [82, Figure].

It has been estimated that all-arterial grafting is possible in 90% of patients using various conduits and their configurations [55], and even patients with advanced age have been shown to benefit from all-arterial revascularization strategies in terms of freedom from recurrent coronary events and improved graft patency [83].
