Nov. 4, 2009 -- Coronary artery bypass surgery performed on a beating heart without the aid of a heart-lung machine proved no more effective than traditional bypass surgery, a study comparing the two procedures shows.
Roughly 1,000 patients treated at 18 Veterans Administration hospitals across the country received beating heart, or "off-pump" bypass surgery. A similar number received "on-pump" surgery, performed while their hearts were stopped.
The two treatment groups had similar outcomes with regard to survival and medical complications within 30 days of surgery.
But composite outcomes a year later appeared to favor the on-pump procedure; the off-pump surgery offered no advantage in terms of neurological outcomes, such as memory loss and concentration.
The study appears in the Nov. 5 issue of TheNew England Journal of Medicine.
These days, about one in five coronary artery bypass graft (CABG) patients in the U.S. get the off-pump surgery.
Cardiovascular surgeon and study co-researcher Frederick Grover, MD, of the University of Colorado, Denver, tells WebMD that he doesn't expect this number to drop drastically as a result of the findings.
"I would expect surgeons who are expert at performing the [off-pump] procedure and who are getting excellent results to keep doing it," he says. "But I imagine that at some institutions, fewer of them will be done."
Beating Heart Bypass
First performed a little over a decade ago, the beating-heart CABG procedure became popular because it was widely believed to be associated with fewer postsurgical physical and cognitive complications.
With CABG, a blockage or area of severe narrowing in a coronary artery is bypassed with a piece of vein or artery called a graft. The graft is connected above and below the blocked area so that blood flow is restored.
Usually patients needing bypass surgery will have more than one blood vessel that requires a graft. The process of re-establishing blood flow in blocked or severely narrowed vessels is referred to as revascularization.
Bypass has been linked to complications such as memory loss, muddled thinking, and concentration problems lasting weeks to months after surgery. Placement on a heart-lung machine has been implicated, but not proven, as a possible contributor to this cognitive impairment.
The VA study was designed to compare cognitive and physical outcomes with the two procedures at 30 days and one year post-treatment.
Researchers randomly assigned 2,203 patients scheduled for urgent or elective CABG to the beating heart or stopped-heart procedures.
"Our trial did not show any overall advantage to the use of the off-pump as compared with the on-pump cardiac surgical approach for coronary bypass," the researchers write. "Instead, there was a consistent trend toward better outcomes in patients undergoing conventional on-pump CABG technique."
Almost all of the patients in the VA study were men and they tended to be younger (average age 63) and low to moderate risk. Because of this, it is not clear if the off-pump procedure offers advantages for women or for older and sicker patients.
Cardiac surgeon Juan Grau, MD, who routinely performs the off-pump surgery, reviewed the research for WebMD.
He pointed out that the off-pump patients in the study ended up having fewer grafts than had been anticipated prior to surgery, suggesting that their revascularization was incomplete.
Grau is an assistant professor of surgery at the University of Pennsylvania School of Medicine Medical Center.
"This study says more about how these surgeries were carried out than it does about the two procedures," he says. "It shows that if you don't revascularize fully, you will pay the price."
Grau also pointed out that the poorer outcomes in the off-pump group were largely confined to patients whose grafts were taken from a vein in the leg rather than an artery from the chest.
"You would expect to see worse outcomes in patients who get vein grafts because they are not the best choice for coronary bypass surgery," he says.
Duke University Medical Center professor of medicine Eric David Peterson, MD, MPH, says the study makes a convincing case that off-pump surgery is not markedly superior to on-pump surgery in relatively healthy men.
"The general message to surgeons who are not doing off-pump surgery is that there is, at present, no compelling need to learn the technique," he tells WebMD.
But in an editorial published with the study, Peterson writes that the new research will not likely end the debate about off-pump and on-pump CABG surgery.