Chapter 22

Coronary artery bypass grafting (CABG) continues to be a valuable method of myocardial revascularization. Despite the increased prevalence of percutaneous coronary intervention to treat coronary disease, as well as improvements in medical therapy, surgical revascularization will continue to have a major role in patients with coronary disease. Currently, the majority of surgical revascularization is performed with the use of cardiopulmonary bypass, with most surgeons preferring to perform distal anastomoses on an arrested heart. Advocates of this approach cite low morbidity and mortality with outcomes that have continued to improve despite a surgical patient population with increasing comorbid conditions and more advanced and severe coronary disease. However, complications, albeit infrequent, continue to plague a small percentage of patients undergoing coronary artery bypass surgery. These include stroke, renal failure, and respiratory failure. These complications may occur not only because of the systemic inflammatory activation that occurs with extracorporeal circulation, but also because of the manipulation of the aorta required for cannulation, cardiopulmonary bypass, and aortic clamping. Off-pump coronary artery bypass grafting (OPCAB) has been increasingly used over the past decade for surgical coronary revascularization. The interest in off-pump techniques has largely been driven by the increased awareness of the deleterious effects of cardiopulmonary bypass and aortic manipulation. Although many centers have adopted this technique, OPCAB use appears to have reached a plateau in recent years and currently accounts for approximately 22% of coronary artery bypass cases (Data Analyses of the Society of Thoracic Surgeons National Adult Cardiac Database, 2008). For most surgeons, the lack of compelling evidence in randomized controlled trials supporting OPCAB over conventional on-pump coronary artery bypass (CCAB) has been an impediment to implementing this strategy in routine practice. Furthermore, many surgeons consider an off-pump approach more technically challenging, with new risks not familiar to on-pump surgery. It is important to note that the aforementioned randomized trials have enrolled predominantly low-risk patients and have sample sizes that are inadequate to demonstrate differences between groups for infrequently occurring events, such as death, stroke, and myocardial infarction. Nonetheless, randomized controlled trials have almost uniformly demonstrated reduced transfusion requirements, lower postoperative serum myocardial enzyme levels, and shorter length of stay. Moreover, there are many retrospective trials showing a survival benefit as well as reduced morbidity with OPCAB. These retrospective database studies have much larger sample size and include mixed-risk patients. However, inherent selection bias may limit the interpretation of these results, despite advanced statistical methodology. For many surgeons to consider implementing an off-pump approach, the following must be demonstrated: (1) equivalent short- and long-term patency rates; (2) complete revascularization; (3) reduced morbidity and even reduced mortality, especially in high-risk patients; and (4) cost efficiency both in the operating room and during the entire hospitalization. For certain high-risk subgroups, it would appear intuitive that avoiding the systemic effects of cardiopulmonary bypass as well as aortic manipulation would reduce the incidence of specific complications such as stroke and renal failure. However, until definitive studies yield superiority of one technique over the other, ...

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