**9. Total Arterial Revascularization (TAR)**

saphenous vein grafts (p = 0.03). For the secondary endpoint of complete occlusion, 8.9% of radial artery grafts were completely occluded compared with 18.6% of saphenous vein grafts

Zacharias *et al.* compared 6-year outcomes in propensity matched CABG patients receiving LIMA to LAD grafts who also received either radial artery grafts or vein grafts only. The authors found that mortality rates were 67% and 98% greater in vein patients than in radial artery patients after 1 and 6 years, respectively. While LIMA patencies were always signifi‐ cantly greater than both radial and vein patencies, 6-year radial graft patencies were system‐ atically greater than that of vein grafts, although the results failed to reach statistical significance. Overall, the use of the radial artery as a second arterial conduit in LIMA to LAD

Collins *et al.* compared 142 patients receiving either radial artery or saphenous vein grafted to the left circumflex coronary artery, with the end point being 5-year angiographic patency. 98.3% of radial artery grafts and 86.4% of saphenous vein grafts were found to be patent after the 5-year angiographic study of 103 patients (p = 0.04). The rate of graft narrowing was also significantly less in radial artery grafts compared to vein grafts, with narrowing occurring in 10% of patent radial artery grafts and 23% of patent saphenous vein grafts (p = 0.01) [28].

A smaller study by Cameron *et al.* also examined the 5-year angiographic patency results of radial artery grafts. Grafts that displayed a string sign were considered not patent. With a radial artery graft patency rate of 89%, the authors found that the radial artery had a patency rate similar to that of other grafts, although the study was too small to determine whether or not this result was statistically significant [29]. Acar *et al.* report similar results for radial artery

Not all studies of radial artery use have been favorable. In a review of 310 patients receiving radial artery grafts between 1996 and 2001, Khot *et al.* found significantly lower patency rates for radial artery grafts when compared to IMA grafts, and similar patency rates when compared to saphenous vein grafts after a mean follow up of 565 ± 511 days. Patency rates of radial artery grafts, LIMA grafts, and saphenous vein grafts were 51.3%, 90.3%, and 64.0%, respectively. While patency rates were similar between radial artery and saphenous vein grafts, there was a significantly higher incidence of severe disease in radial artery grafts (p = 0.0003). Women were also found to have significantly lower radial artery patency rates than men [31]. However, Desai *et al.* specifically note that this study did not use randomized controls, standardized surgical methods, concurrent pharmacology, or routine angiographic

**8. RIMA versus radial artery as a second choice arterial conduit**

With favorable clinical results for both RIMA and radial artery use, it is then necessary to decide which is the better choice as a second arterial conduit when attempting to achieve multiple

CABG patients is associated with improved long-term survival [27].

graft patencies when compared to the LIMA [30].

follow-up that could lead to potential bias [25].

arterial revascularization.

(p = 0.002) [26].

126 Artery Bypass

The clinical benefits of RIMA and radial artery use have been established, and many studies have indirectly examined the results of TAR in patients receiving BIMA or radial artery grafts without the need of concomitant saphenous vein grafts. However, few studies have specifically compared the clinical outcomes of TAR to conventional CABG procedures.

In a prospective study by Muneretto *et al.,* 200 patients over 70 years of age were randomized into two groups either receiving TAR or conventional CABG (LIMA to LAD with additional saphenous vein grafts if needed). Even though 31% of patients in the TAR group received BIMA grafts, the incidence of perioperative sternal wound complica‐ tions was found to be 1% in both groups. At the mean follow up of 15 months, the inci‐ dence of cardiac-related events (MI, angina, coronary angioplasty, and graft occlusion) was significantly higher in the conventional CABG group compared to patients receiving TAR. The presence of diabetes and hyperlipidemia had a negative impact on clinical out‐ come, especially in patients receiving saphenous vein grafts in the conventional CABG group. Conventional CABG surgery was also found to be significantly associated with coronary graft occlusion. Overall, at follow-up, TAR resulted in improved clinical out‐ comes in patients undergoing CABG procedures when compared to conventional CABG [34].

MA grafts have also been shown to be similar to those of the LIMA, even when consid‐ ering the sites of distal anastomoses and the proximal anastomosing techniques [16, 17, 18, 19, 20]. Further studies are needed to determine if there is any significant effect on

Total Arterial Revascularization in Coronary Artery Bypass Grafting Surgery

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

129

The incidence of SWI has been a significant concern for surgeons, especially among high-risk patients such as the morbidly obese, insulin-dependent diabetics, and those with COPD. BIMA harvesting is generally avoided in these patients [7, 8], however studies have shown that BIMA harvesting in general does not significantly affect the incidence of SWIs [12, 23]. The risk of SWI can be even further reduced with the use of skeletonized BIMA harvesting rather than

Studies have shown that the radial artery is also a good choice for an arterial conduit after the LIMA. Studies examining clinical outcomes and patency rates of the radial artery have been mixed, with some studies showing better short-term patency rates than saphenous vein grafts [25-28], while other studies have shown that radial artery outcomes are at least similar to those

While not all studies have been favorable with regards to BIMA and radial artery use [11, 15, 32, 33], studies generally find patency rates and clinical outcomes of these two arterial conduits are at least as good as the currently accepted standards of care, which should give surgeons flexibility in their choice of conduits, ultimately leading to total arterial revascularization.

Studies in general have provided favorable results for TAR, with TAR at least being similar in outcomes to conventional CABG [35]. Several studies have demonstrated that TAR, and the use of arterial conduits in general, provides significantly better late survival (especially in patients with three vessel coronary disease), cardiac event-free survival, and improved health-

With favorable results for the use of arterial conduits and results that are at least as good as those seen in conventional CABG, these results should allow surgeons flexibility in their choice of conduits. Due to the significantly increased long-term survival advantages over saphenous vein grafts, BIMA use should be particularly indicated for younger patients, with special attempts to achieve TAR in patients with three vessel disease. Especially with skeletonized harvesting, BIMA may be safe to use in high-risk patients for SWI, such as insulin-dependent diabetics. BIMA use may also decrease the incidence of postoperative cerebrovascular events due to the decreased manipulation of the ascending aorta if both IMAs are used *in situ.* The radial artery is also a suitable conduit to use in conjunction with BIMA or as a second arterial conduit if either the LIMA or RIMA is not suitable for use. This ultimate flexibility provided by TAR should allow surgeons to determine their revascularization strategies not based on the availability of conduits, but by the possible co-morbidities and post-operative complica‐

related quality of life when compared to conventional CABG [11, 21, 36].

operative length in BIMA grafting versus conventional CABG.

pedicled harvesting [22, 23].

**11. Conclusion**

for the RIMA and saphenous vein [11, 32, 33].

tions that may arise based on the patient in question.

In a more recent, long-term study with a mean follow-up of 6 years, Chung *et al.* exam‐ ined 503 patients undergoing isolated CABG procedures for three-vessel coronary dis‐ ease. Patients in the study either received TAR (117 patients) or conventional revascularization (386 patients). In both the crude analysis and propensity-score matched analysis, there was no significant difference in the rates of death, reintervention, MI, or stroke between the patients receiving TAR or conventional CABG. However, the study did not examine graft patency. The authors conclude that, since the outcomes were simi‐ lar between the two groups, "the selection of conduit should be more liberal" [35].

Zacharias *et al.* conducted a long-term study of 4,743 patients undergoing multivessel CABG procedures receiving either TAR (612 patients) or conventional CABG (4,131 pa‐ tients). Early, 30-day mortality was similar for both patient groups, with a 1.30% mortali‐ ty rate in the TAR group and a 1.67% mortality rate in the conventional group. Due to significant differences in the patient cohort for the two groups, propensity-matched anal‐ yses were performed for the 12-year follow up. Late survival was found to be significant‐ ly better in total arterial patients with three-vessel disease compared to conventional CABG patients with three-vessel disease (p < 0.001). However, there was not a significant difference in late survival between the two groups for patients with two-vessel disease (p = 0.89). The authors also noted that the completeness of myocardial revascularization was "critical for maximizing the achievable long-term benefits of total arterial grafting" [36].
