CABG completed "off-pump" has no advantages in patient outcomes: Study

Stony Brook UniversityNov 6 2009

A study of 2,203 cardiac surgery patients from Veterans Affairs (VA) medical centers nationwide revealed that coronary-artery bypass grafting (CABG) completed "off-pump," meaning without a heart-lung machine, had no advantages in patient outcomes compared to the traditional "on-pump" procedure. A. Laurie Shroyer, Ph.D., Professor of Preventive Medicine at Stony Brook University and the Northport VA Medical Center, and colleagues from 18 VA medical centers conducted by the VA Cooperative Studies Program Coordinating Center in Perry Point, reported their findings in the November 5 issue of The New England Journal of Medicine. The article, "On-Pump Versus Off-Pump CABG," can be found online at http://content.nejm.org/

According to the National Institutes of Health, coronary heart disease is progressive disease that affects 15.8 million Americans. Over the past 30 years, CABG has usually been performed with the cardiopulmonary bypass pump (heart-lung machine). In the mid-1990s, interest grew in performing surgery without the heart-lung machine because of potential clinical concerns and beliefs that off-pump CABG might reduce myocardial damage, complications, and limit neurocognitive deficits post-surgery.

"Earlier studies showed some advantages of CABG surgery using the off-pump procedure, including quicker recovery and less impact on cognitive function, but our large multicenter study contradicts these earlier findings," says Dr. Shroyer, Co-Principal Investigator. "In fact, the VA study indicates a consistent trend toward better outcomes in patients who had undergone the conventional on-pump technique, with better one-year composite outcomes and grafts remaining open at one year for on-pump patients."

Called the ROOBY(Randomized On/Off Bypass) trial, the study enrolled 1,099 to on-pump and 1,104 to off-pump elective surgery. Most patients were male, white, current or former smokers with one or more chronic health problems. ROOBY began enrolling patients in 2002 and ended in May 2008.

The primary short-term end point in the patient population included a composite of death or complications post-surgery, such as re-operation, new mechanical support, or cardiac arrest within 30 days after surgery. The primary long-term end point was a composite of death from any cause, a repeat revascularization procedure, or a nonfatal heart attack within one year after surgery. Secondary end points included completeness of revascularization, graft patency at one year, and neuropsychological outcomes.

The researchers found that with short and long-term end points, no significant differences were found between off-pump and on-pump CABG, yet most end points were slightly worse in the off-pump CABG group.

They report in the NEJM that the 30-day composite outcome was 7.0 percent for off-pump CABG and 5.6 percent for on-pump CABG. The rate of one-year composite outcome was higher for off-pump than for on-pump CABG (9.9 percent vs. 7.4 percent). The proportion of patients with fewer grafts completed than originally planned was higher with off-pump CABG than with on-pump CABG (17.8 percent vs. 11.1 percent). Follow-up angiograms in 1,371 patients who underwent 4,093 grafts revealed that the overall rate of graft patency was lower in the off-pump group (82.6 percent) than the on-pump group (87.8 percent). The researchers also found no clinically relevant advantages in neuropsychological outcomes with the off-pump technique.

Despite the study results, the researchers urge that longer-term follow-up is needed to clearly establish if there are subsequent impacts related to the stability and durability of the off-pump procedure.

ROOBY is the first published conclusive trial comparing on-pump versus off-pump CABG approaches. The study was supported and conducted by the Department of Veterans Affairs Cooperative Studies Program, with additional support from the Offices of Research and Development at the Eastern Colorado Health Care System VA Medical Center in Denver, and the Northport VA Medical Center in Northport, N.Y.

The study's Principal Investigator team included Frederick L. Grover, M.D., of the Denver VA Medical Center, and Dimitri Novitzky, M.D., of the Tampa VA Medical Center, working collaboratively with Dr. Gerald McDonald as the primary VA Central Office representative.

Dr. Shroyer says that under the guidance of the Cooperative Studies Program, the team of VA-based physician investigators and research study nurses were primarily responsible for the ROOBY trial's successful completion. Additionally, she noted that the VA research enterprise provided funding for the Neuropsychological Outcomes Core Lab (directed by Dr. Elizabeth Kozora) and the Cardiac Catheterization Core Lab (led by Dr. Brack Hattler), which were unique study features unlikely to be repeated in other research settings.