Despite the increased prevalence of percutaneous coronary intervention (PCI) to treat coronary disease, coronary artery bypass graft (CABG) will continue to have a major role, particularly in patients with complex multivessel disease and diabetes mellitus. Currently, the majority of surgical revascularization is performed with the use of cardiopulmonary bypass (CPB), 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.1-3 However, complications, albeit infrequent, continue to plague a small percentage of patients undergoing CABG including stroke, renal failure, and respiratory failure. These complications 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, CPB, and aortic clamping. The interest in off-pump techniques was largely driven by the increased awareness of the deleterious effects of CPB and aortic manipulation.
According to the Society of Thoracic Surgeons Adult Cardiac Surgery Database (STS ACSD), off-pump CABG (OPCAB) use peaked in 2002 (23%) followed by a decline, accounting for approximately 17% of CABG cases in 2012.4 For most surgeons, the lack of compelling evidence in large randomized controlled trials (RCTs) supporting OPCAB over conventional on-pump coronary artery bypass (ONCAB) and suggestions of more frequent incomplete revascularization have been impediments to implementing this strategy in routine practice.1-3,5,6 Nonetheless RCTs 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. 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 individual 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 CPB as well as aortic manipulation would reduce the incidence of specific complications such as stroke and renal failure.
An off-pump approach is more technically challenging, with new risks not familiar to on-pump surgery. Therefore, OPCAB should be considered an advanced technique, not to be performed by all surgeons but by a select few who have trained with experts in OPCAB and who themselves perform large numbers of OPCAB procedures. Finally, there is greater appreciation that OPCAB should be performed in revascularization centers of excellence, incorporated into a comprehensive approach to revascularization, which includes minimally invasive CABG, hybrid, and total arterial revascularization.