Off-Pump Bypass Surgery - Ready for the Big Dance?

EVERY SPRING, COLLEGE BASKETBALL TEAMS FROM around the United States gear up for a competition to determine the best team of the year. This tournament is often referred to as the “big dance,” and it represents the ultimate challenge of peer against peer. In this contest, dominance in prior years is no guarantee of continued success. In medicine, new technologies are continuously being developed to challenge the champions of prior years, but there is no calendar marking when a new therapy is ready for its “big dance”—the large multicenter randomized trial that can determine whether it should displace the reigning champion of conventional care in clinical practice. If the assessment comes too early as the therapy is still evolving, a promising treatment may be inappropriately discarded. If the assessment comes too late, practitioners may have already decided to adopt the therapy based on less rigorous evidence and may refuse to enroll patients into a trial based on “ethical grounds.” Over the last few years, much interest has focused on the evolving contest between coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass and offpump coronary artery bypass (OPCAB) surgery. Observational data suggest significant outcome advantages for the newcomer, OPCAB, yet it remains controversial. Many senior surgeons have resisted abandoning the CABG procedure they have performed comfortably for decades in favor of an unproven new procedure that is substantially more difficult for the surgeon and the anesthesiologist. Thus, the contest between conventional CABG with cardiopulmonary bypass and the newer OPCAB has all the makings of a classic matchup. But is OPCAB ready for its “big dance”? Before answering this question, consideration of some additional background is appropriate. The development of cardiopulmonary bypass using the heart-lung machine is a watershed accomplishment of medicine in the 20th century. With varying details, CABG with cardiopulmonary bypass has been used for more than 30 years and has evolved into a safe procedure that is performed in more than 300000 patients each year in the United States. However, research has shown that routing the patient’s circulation through the bypass machine activates a number of undesirable pathogenic processes that have been implicated in major complications following surgery. Looking to improve patient outcomes, pioneering cardiac surgeons began attempting bypass grafting on a “beating” heart. Early OPCAB procedures identified some important challenges to this approach, including intraoperative hemodynamic instability during manipulation of the heart, difficulty providing complete revascularization (particularly of the lateral and posterior walls), and higher risks for anastomotic failures. Since these early days, OPCAB has rapidly evolved with better devices for stabilizing the heart, anesthetic techniques, and improved surgeon experience. As the technique has been refined, its proponents have ventured to compare it directly with CABG with cardiopulmonary bypass in randomized trials. However, these initial trials have a number of important limitations. They generally have been small, single-center (and often singlesurgeon) trials. Additionally, these early trials have tended to exclude severely ill patients as demonstrated by mortality rates that are 2-fold to 3-fold lower than national norms in both the CABG with cardiopulmonary bypass and OPCAB patients. Nonetheless, some trials observed benefits in OPCAB including reduced perioperative myocardial damage (elevations in creatinine kinase levels) and lower rates of renal dysfunction, atrial fibrillation, stroke, sternal wound infection, and need for transfusion. The OPCAB procedure has also been associated with reduced postoperative ventilation time, shorter hospital stays, and lower costs. However, the available trials have not been uniformly supportive of the OPCAB approach. One area in which the newer procedure may be less satisfactory is in completeness and durability of revascularization. On these points, recent trials have reached different conclusions. At one end are the re-