A recent large multicenter randomized trial published in the New England Journal of Medicine examined the 5-year outcomes after bypass surgery in the Randomized On/Off Bypass (ROOBY) trial. The results further support on-pump coronary artery bypass grafting (CABG) as the preferred surgical technique for patients who are not otherwise at high risk for cardiopulmonary bypass (CPB) (1).
Performing CABG using CPB with cardiac arrest, also known as on-pump CABG, has been the most commonly used CABG technique since its inception in the 1960s. Though highly successful at revascularization, complications of CABG using CPB with cardiac arrest include cognitive dysfunction and strokes from required manipulation and cross-clamping of the aorta.
In an effort to reduce these risks, off-pump CABG performed while the heart is beating has been used as an alternative technique for revascularization (2). Results from prior research more limited in follow-up time, including 1-year follow-up of the ROOBY trial, did not demonstrate the hypothesized reduction in complications, and a Cochrane systematic review surprisingly found increased all-cause mortality in patients who underwent off-pump CABG (3, 4). Further complicating the choice of surgical technique, a recent trial including higher surgical risk patients showed a trend toward increased need for revascularization in the off-pump CABG patients at 1 year that did not persist at longer follow-up (5, 6).
What did this study show?
The 5-year follow-up results of the ROOBY trial further clarify best practice regarding on-pump versus off-pump CABG. Of 2,203 patients randomized to on-pump or off-pump CABG at 18 Veterans Affairs medical centers, the rate of death at 5 years was 3.3% higher in the off-pump group compared to the on-pump group (15.2% vs 11.9%; relative risk (RR), 1.28; 95% confidence interval (CI), 1.03-1.58; p = 0.02). In addition, the rate of the combined endpoint of death from any cause, repeat revascularization, or nonfatal myocardial infarction was 31.0% in the off-pump group compared to 27.1% in the on-pump group (RR, 1.14; 95% CI, 1.00-1.30; p = 0.046)(1).
What is the take-away?
So, should off-pump CABG be relegated to surgical text books? This large, randomized, well-designed trial, taken together with prior studies, certainly continues to decrease prior enthusiasm for the more technically challenging off-pump bypass. The mounting evidence of improved outcomes, including reduced mortality, supports the use of on-pump CABG for the majority of patients. Nevertheless, there are exceptions. In preparation for bypass surgery, patients often have their aorta evaluated for atherosclerosis. If a patient is found to have a heavily calcified aorta, commonly termed a porcelain aorta, the high risk of stroke from manipulation of the aorta offsets the potential benefits of on-pump CABG and off-pump still remains a reasonable approach in the hands of an experienced surgeon.
Although continued long-term follow-up of comparative trials will certainly inform practice, future work should aim to better identify patients at high risk of complications from on-pump CABG who may benefit from off-pump CABG. In the meantime, on-pump CABG appears to be the best option for most people.
1. Shroyer AL, Hattler B, Wagner TH, et al: Five-year outcomes after on-pump and off-pump coronary-artery bypass. N Engl J Med 377(7):623–632, 2017.
2. Hillis LD, Smith PK, Anderson JL, et al: 2011 ACCF/AHA Guideline for Coronary Artery Bypass Graft Surgery. A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Developed in collaboration with the American Association for Thoracic Surgery, Society of Cardiovascular Anesthesiologists, and Society of Thoracic Surgeons. J Am Coll Cardiol 58(24):e123–210,2011.
3. Shroyer AL, Grover FL, Hattler B, et al: On-pump versus off-pump coronary-artery bypass surgery. N Engl J Med 361(19):1827–1837, 2009.
4. Moller CH, Penninga L, Wetterslev J, Steinbruchel DA, Gluud C: Off-pump versus on-pump coronary artery bypass grafting for ischaemic heart disease. Cochrane Database Syst Rev. 2012(3):Cd007224.
5. Lamy A, Devereaux PJ, Prabhakaran D, et al: Effects of off-pump and on-pump coronary-artery bypass grafting at 1 year. N Engl J Med 368(13):1179–1188,. 2013
6. Lamy A, Devereaux PJ, Prabhakaran D, et al: Five-year outcomes after off-pump or on-pump coronary-artery bypass grafting. N Engl J Med 375(24):2359–2368, 2016.