Performing a common heart surgery without bypassing the cardiopulmonary system may cut down on the number of surgery-related strokes and other short-term complications, according to a new report by the Agency for Healthcare Research and Quality (AHRQ). Traditionally, coronary artery bypass graft (CABG) surgery has depended heavily on cardiopulmonary bypass (CPB), particularly as the harmful effects of CPB have been reduced. However, many cardiac surgeons have become interested in avoiding CPB altogether, a procedure known as "off-pump" CABG surgery. CABG surgery creates new paths around blocked arteries to improve blood flow to the heart. CPB stops the heart to allow surgeons to create the new pathways. The surgery was originally conceived as requiring CPB; however, CPB carries risks of adverse effects on the heart, brain, lungs, kidney, and other organs, and some surgeons believe that CPB is not required for a surgery aiming to restore blood supply to the heart—leading them to consider off-pump CABG as a less-invasive alternative with the potential to be less costly.
Researchers found that off-pump CABG is associated with lower incidence of stroke, atrial fibrillation, and health care-associated infection. The study, conducted by Artyom Sedrakyan, M.D., Ph.D., a cardiothoracic surgeon and health services researcher at AHRQ, and colleagues, is the first to document significant benefits of off-pump CABG in randomized trials. Specifically, they found the off-pump procedure could prevent approximately 10 strokes per 1,000 CABGs, a 50 percent reduction in the risk faced by patients undergoing the surgery.
The researchers analyzed data from 41 randomized clinical trials that included 3,996 patients whose procedures took place after 1999. They found that off-pump CABG was associated with a 30 percent reduction in atrial fibrillation (abnormal heart rhythm) and a 48 percent reduction in wound infection (translating to avoidance of 80 cases of atrial fibrillation and 40 infections, respectively, per 1,000 off-pump CABGs).
The study also found that off-pump surgery often involved fewer grafts to bypass coronary lesions as compared with traditional surgery. Fewer grafts could lead to re-interventions, such as repeat angioplasties or surgeries, and have unknown long-term effects. However, researchers found evidence that the difference between off-pump and traditional surgery in the number of bypass grafts used seemed to be small in studies in which more surgeries were performed. This indicates a relationship between the volume of procedures and their outcome. In other words, off-pump surgeries are more successfully performed at facilities that perform many of them.
Dr. Sedrakyan cautioned that this report provides limited evidence of off-pump CABG's benefits. He notes that traditional CABG may still be warranted in many cases and that off-pump CABG carries its own risks, and requires substantial training to learn and perform comfortably.
See "Off-pump surgery is associated with reduced occurrence of stroke and other morbidity as compared with traditional coronary artery bypass grafting," by Dr. Sedrakyan, Albert W. Wu, M.D., M.P.H., Amish Parashar, M.Sc., M.P.H., and others, in the November 2006 Stroke 37(11), pp. 2759-69. Reprints (AHRQ Publication No. 07-R011) are available from the AHRQ Publications Clearinghouse.