Long-term outcomes of off-pump vs. on-pump coronary artery bypass grafts. August 12, 2007

August 24, 2007 By Benjamin A. Olenchock, M.D. Ph.D. [mailto:bolenchock@partners.org]

New York

Coronary artery bypass graft surgery (CABG) is the standard of care for coronary revascularization in patients with significant left main coronary artery stenosis or three-vessel coronary artery disease with depressed ejection fraction, especially in diabetic patients. In the past decade, many heart surgeons have become more proficient at doing this surgery off-pump, i.e. without the heart-lung bypass machine. With an off-pump CABG (OPCABG) surgery, the conduits are attached while the heart is full of blood and beating normally. Avoiding extracorporeal oxygenation of blood is thought to have many advantages, including a decreased risk of stroke or atrial fibrillation. However, graft patency might be better with on-pump surgeries. This new study has used the large New York State’s Cardiac Surgery Reporting System to compare short and long term outcomes in almost 50,000 CABG operations.

In New York, almost 30% of the isolated CABG surgeries done are off-pump. This is a dramatic increase from a 1997, when only 3% of cases were done off-pump. Much of this shift is due to changes in the experience of surgeons and the perception that long-term outcomes are similar off- vs. on-pump, while short-term complications are fewer with OPCABG. With regard to short-term outcomes, OPCABG was found to have a smaller 30-day mortality (HR 0.8, CI 0.68-0.97). There was a diminished risk of stroke (1.2 vs. 1.5%, HR 0.7, p=0.0006) and respiratory failure (3.7 vs. 4.2%, HR 0.8, p=0.005) with OPCABG, while the need for unplanned reoperation was higher (1.2 vs. 0.8%, HR 1.47, p=0.047). With regard to long-term outcomes, there was no statistical difference in 3-yr adjusted survival off-pump vs. on-pump (89.4 vs. 90.1) while there was a clear difference in freedom from revascularization (89.9 vs. 93.6%).

The question remains whether the increased need for revascularization in patients undergoing OPCABG is due to incomplete revascularization vs. graft failure. This is an important distinction because the former might be a technical issue which could be improved with experience. Interestingly, a subgroup analysis limited to high-volume, experienced surgeons found concordant results, meaning these results were not due to inexperience alone. The inevitable bias of patient selection should be acknowledged when interpreting this study. However, combined with recent randomized control trials, these data question the long-term advantages of OPCABG. Future analyses will likely help define patient or anatomic characteristics which confer an advantage to one surgical technique or the other.


 * 1) ref1 pmid=17709642