**1. Introduction**

142 Special Topics in Cardiac Surgery

Heit, J. (2002) Venous thromboembolism epidemiology: implications for prevention and management. *Semin Thromb Hemost*, 28(Suppl 2),(June 2002), pp. (3-13) Hirsh, J., & Hoak, J. (1996). Management of deep vein thrombosis and pulmonary embolism.

Kasper, W., Constantinides, S., Geibel, A., Olchewski, M., Heinrich, F., Grosser, K., Rauber,

multicenter registry. *J Am Coll Cardiol*, 30, (November 1997), pp. (1165-1171) Khurana, A., & Tak, T. (2004). Venous thromboembolic disease presenting as inferior vena

Krug, H., & Zerbe, F. (1980). Major venous thrombosis: a complication of transvenous

Kucher, N., Rossi, E.,De Rosa, M., & Goldhaber, S. (2006). Massive pulmonary embolism.

Kuchar, N. (2007). Catheter embolectomy for acute pulmonary embolism. *Chest*, 132,

Lohr, J., Kerr T, Lutter, K., Cranley, R., Spirtoff, K, & Cranley, J. (1991). Lower extremity calf

Lopez J., Kearon C., & Lee A. (2004). Deep venous thrombosis. *Proceedings of American Society of Hematology*, San Diego, California, (December 2004), pp. (439 – 464) Mulvihill, S., & Fonkalsrud E. (1984). Complications of superior versus inferior vena cava

Nahimyak, V., Yoon, S., & Holland, C. (2006). Acousto-mechanical and thermal properties of

Schreiber, D. (2010). Deep venous thrombosis and thrombophlebitis. In: *eMedicine Emergency* 

Siqueira-Filho, A., Kottke, B., & Miller W. (1976). Primary inferior vena cava thrombosis.

Schmitz-Rode, T., Jannsens, U., Schild, H., Basche, S., Hanrath, P., & Gunther, R. (1998).

Stein, P., Alnas, M., Beemath, A., & Patel, N. (2007). Outcome of pulmonary embolectomy.

Thabut, G., Thabut, D., Myers, R., Bernard-Chabert, B., Marrash-Chahla, R., Mal, H., &

Tibbutt, D., Davies J., Anderson, J., Fletcher, E., Hamill, J., Holt, J., Thomas, M., Lee, G.,

Verstraete, M., Miller, G., Bounameaux, H., Charbonnier, B., Colle, J., Lecorf, G., Marbet, G.,

embolism. *Circulation*, 77(2), (February 1988), pp. (353-360)

Fragmentation of massive pulmonary embolism using a pigtail rotation catheter.

Fournier, M. (2002). Thrombolytic therapy of pulmonary embolism. *JACC*, 40(9),

Miller G., Sharp, A., & Sutton, G. (1974). Comparison by controlled clinical trial of streptokinase and heparin in treatment of life-threatening pulmonary embolism.

Mombaerts, P., & Olsson, C. (1988). Intravenous and intrapulmonary recombinant tissue-type plasminogen activator in the treatment of acute massive pulmonary

clotted blood. *J Acoust Soc Am*, 119(6), (June 2006), pp. (3766-3772)

thrombosis: To treat or not to treat? *J Vasc Surg*, 14(5), (November 1991), pp. (618-623)

occlusion in infants receiving central total parenteral nutrition. *J Pediatr Surg*, 19(6),

pacemaker electrodes. *Br Heart J*, 44,(August, 1980), pp.(158-61)

K., Iversen, S., Redecker, M., & Kienast, F. (1997). Management strategies and determinants of outcome in acute major pulmonary embolism: Results of a

cava thrombus extending into the right atrium. *Clinical Medicine & Research*,2(2),

*Circulation*, 93, (June 1996), pp. (2212-2245)

*Circulation*, 113(4), (January 2006), pp. (577-582)

(May 2004), pp. (125-127)

(August 2007), pp. (657-663)

(December 1984), pp. (752-757)

*Medicine*, March 27, 2011, Available from:

http://emedicine.medscape.com/article/1911303-overview

*Arch Intern Med*,136(7), (July 1976), pp. (799-802)

Chest, 114, (November 1998), pp. (1427-1436)

(November 2002), pp. (1660-1667)

*BMJ*, 1, (March 1974), pp. (343-347)

*Am J Cardiol*, 99(3), (February 2007), pp. (421-423)

Coronary artery bypass grafting (CABG) is one of the most studied operations in medical history, but many of the data forming the basis for clinical decisions in patients with coronary artery disease (CAD) were derived in the 1970s and 1980s, when the procedure and medical therapy were in their relative infancy. Advances in medical therapy (beta adrenergic blockers, thienopyridines, statins, and others), percutaneous coronary interventions (PCI), and surgical techniques have changed the decision making for patients with CAD. In addition, patient populations referred for surgery have changed since the original studies documenting advantages of CABG over other forms of therapy.

Since percutaneous transluminal coronary angioplasty (PTCA) was introduced, significant advances have been made in the percutaneous treatment of CAD. When drug-eluting stents (DES) were introduced in the early 2000s, many predicted the demise of CABG surgery. Enthusiasm for percutaneous treatment of CAD has most recently led to promoting PCI for unprotected left main coronary artery (LMCA) disease, an anatomical state typically reserved for CABG [1-3]. Percutaneous options have indelibly changed the face of CABG surgery and raise questions concerning the "gold standard" of care in coronary revascularization. For instance, recent reports document that patients referred for redo coronary artery surgery have declined, presumably due to the increased enthusiasm, possibly among surgeons themselves, for PCI in this setting [4]. Despite this, few studies have actually compared PCI with CABG. Two notable studies are recently available, both demonstrating advantages for CABG over PCI for left main CAD and/or three-vessel CAD [5, 6].

Concurrently, details pertaining to short-term outcomes of CABG have been questioned. For example, historical saphenous vein graft (SVG) patencies were reported as approximately 50% at 10 years [7]. However, several studies published in the mid-2000s indicate that earlyterm patencies of aorto-coronary SVG conduits are not as good as the historical figures that are still often quoted [8-10]. While the long-term patency and performance of the left internal mammary artery (LIMA) has not been questioned, the recent poor performance of

<sup>\*</sup> Corresponding Author

Conduit Selection for Improved Outcomes in Coronary Artery Bypass Surgery 145

PCI was introduced in 1977 and has undergone consistent improvements in technologies and approaches, offering a less invasive treatment modality for CAD [25]. With the introduction of DES in 2003, the percentage of CAD patients treated with PCI have increased consistently [26, 27]. However, recent studies evaluating long-term outcomes for DES have revealed increased morbidity and mortality secondary to late stent thrombosis [28-30]. While DES therapy has reduced need for target lesion reintervention [31, 32], there is a strict therapeutic requirement for dual anti-platelet therapy (DAPT). Current DAPT recommendations are for at least one year after DES therapy, but the ideal length of

Shortly after the emergence of PCI as a reliable and durable therapy for CAD, comparisons between angioplasty and CABG were designed in order to determine the relative advantages of each modality. The BARI (Bypass Angioplasty Revascularization Investigation) trial compared balloon angioplasty with CABG in patients with multivessel CAD and severe angina or inducible coronary ischemia. After 5 and 10 years follow-up, no difference in long-term survival was demonstrated [34, 35]. Similar results were noted in other randomized trials of PTCA versus CABG [36, 37]. It was commonly noted in these trials that reintervention for recurrent angina symptoms was significantly more common for patients treated with an initial strategy of PTCA [BARI, RITA, GABI]. However, on subgroup analysis, survival advantage for CABG was demonstrated among diabetic patients in the BARI trial [35]. Finally, a meta-analysis of 13 randomized controlled trials comparing CABG with PTCA showed improved survival for CABG at 5-8 years in those

Even as studies comparing PTCA with CABG were enrolling, bare-metal stents (BMS) were introduced, and trials to compare the new technology with CABG emerged. The randomized Stent or Surgery (SoS) trial compared multivessel CAD treatment by CABG or by PCI with BMS [39]. At a median follow-up of 2 years, these data showed reduced rates of coronary reintervention and significantly fewer deaths after CABG. Similar trials comparing CABG and PCI with BMS did not demonstrate a survival advantage for either therapy [40], although diabetic patients appeared to have improved survival after CABG in the Arterial

The US Food and Drug Administration approved DES therapy in 2003, stimulating another round of comparisons between CABG and PCI with the newer technology. Hannan et al reviewed risk-adjusted data from the NY State Dept of Health comparing patients who underwent CABG or PCI with DES for multivessel CAD over a 15-month period shortly after DES approval [5]. At a mean follow-up of 19 months, CABG patients experienced reduced hazard ratio for death, reduced mortality, reduced death/myocardial infarction composite, and less need for repeat revascularization [5]. However, the data were not acquired in the context of a randomized trial. Finally, the SYNTAX trial, a prospective randomized trial conducted across Europe and the US, compared PCI with DES and CABG in patients with 3-vessel CAD, left main CAD, or both [6]. The primary outcomes were major adverse cardiovascular or cerebrovascular events, and follow-up was provided for 12 months after intervention. The SYNTAX data demonstrated increased rates of MACE in the

**2. Percutaneous coronary interventions** 

**3. Comparing coronary bypass surgery and PCI** 

with multivessel CAD and in diabetic patients [38].

Revascularization Therapies Study (ARTS 1) [41].

treatment still not yet known [33].

SVG, coupled with increasing enthusiasm and demand for DES has lead to the emergence of "hybrid" coronary revascularization, typically consisting of LIMA-to-LAD and PCI of other coronary lesions. [11].

Coronary artery surgery itself has undergone several iterative changes recently. In the 1990s, great enthusiasm existed for the "mid-CAB" (minimally-invasive direct coronary artery bypass) procedure, an approach integral to "hybrid" revascularizations and primarily involving a small left anterior thoracotomy to harvest the LIMA and expose the left anterior descending [LAD] coronary artery. However, outside of the context of hybrid procedures, mid-CAB has had little widespread applicability, particularly since most patients referred for coronary surgery have multivessel disease. Introduction of mid-CAB procedures help usher in the era of off-pump CABG, which was heralded as an approach to reduce the risks associated with on-pump CABG, particularly myocardial dysfunction and cerebrovascular complications [12]. Finally, technology has introduced minimally invasive platforms for performing multi-vessel CABG, most recently the introduction of "totally endoscopic" and robotic CABG surgery [13]. However, it should be noted that these "improved techniques" continue to utilize the same conduit selection and comparative trials with objective evidence are lacking. Since minimally invasive strategies for CABG do not routinely incorporate changes to the operation known to improve short- and long-term results, there appears little reason to suspect that graft patency rates will be improved by less invasive procedures. Rather, one could argue that these alterations in approach to CABG are primarily based on industry involvement, public demands for less invasive procedures, and as marketing strategies by hospital systems.

*Are there alternatives to CABG, which could improve long-term outcomes for graft patency and the composite of major adverse coronary events (MACE) particularly when compared with PCI?* The answer is a resounding "yes," and it is found in arterial conduits for coronary bypass. CABG with multiple arterial grafts have been shown to have improved graft patency, reduced need for reoperation or reintervention, and prolonged survival compared with patients undergoing CABG with one IMA and SVG [14-17]. For instance, Sabik et al reviewed a 27 year experience at the Cleveland Clinic with regard to need for reintervention after primary CABG and found that the extent of arterial grafting correlated with freedom from subsequent reintervention [18]. Specifically, patients who received two IMA grafts at initial surgery had approximately 10% risk for reintervention at 10 years; those with one IMA had 20% risk; and those with no IMA had approximately 30% risk for reintervention at 10 years [18].

However, the surgical community has not fully utilized these assets despite numerous, compelling data [19-23]. Jones succinctly summarized the decision point facing conventional, open surgery in the face of rapidly advancing technologies, particularly PCI, and the impact on referral trends for surgical intervention: " improve the long-term outcome, lessen resources used, or both." [24]. Therefore, one important philosophic principle regarding use of multiple arterial conduits is that the focus is on the *long-term* results, not the short-term.

The purpose of this chapter is to review the data available for CABG with multiple arterial grafts including bilateral IMA use, radial artery, and other conduits. Finally, we will demonstrate the advantages of multiple arterial grafting and make the argument that this strategy yields superior long-term results compared to any strategy for coronary revascularization based on PCI or CABG with traditional conduit selection.
