Vein Removal Method Linked to Bypass Results
More long-term problems seen with minimally invasive technique
WEDNESDAY, July 15, 2009 (HealthDay News) -- A study originally designed for a completely different purpose has unearthed a disturbing finding about coronary artery bypass surgery: The way that the vein used for the bypass is removed from the body appears to affect the long-term outcome of the surgery.
People whose veins are removed by the minimally invasive technique called endoscopic harvesting had higher rates of bypass failure, heart attacks and death, according to a report in the July 16 issue of the New England Journal of Medicine.
The finding was entirely unexpected, said study senior author Dr. John H. Alexander, a cardiologist at Duke Clinical Research Institute. The study of 3,000 people who had bypass surgery was designed to determine whether treating the removed veins with a drug would improve results. (It didn't.) Only longer-term analysis of the study data revealed the difference in outcome between veins obtained by endoscopic harvesting and those obtained through conventional surgery.
"The mortality difference did not become apparent for at least nine or 10 months," Alexander said. "No one would have thought you needed a year or more to detect a difference in outcome."
Endoscopic harvesting, which uses a one- or two-inch incision to remove a saphenous vein from a leg, is used in 70 percent of the 450,000 coronary bypass operations done annually in the United States. Conventional surgery, which requires a much longer incision, is used in the other 30 percent of cases. Endoscopic harvesting is popular among surgeons and people having bypasses because it virtually eliminates the risk of infection, excess bleeding and other complications associated with conventional removal.
The journal report does not discuss those advantages. Instead, it focuses on the greater rate of graft failure (46.7 percent versus 38 percent at 18 months), death or heart attack (9.3 percent versus 7.6 percent at three years) and deaths (7.4 percent versus 5.8 percent at three years) seen in those who had endoscopic harvesting.
"This has changed the conversation I have with patients," said Alexander, who does not perform bypass surgery but refers patients for the procedure. "Now we have to be balancing the known short-term benefits of endoscopic harvesting with the long-term risk."
So far, he said, "most patients are still leaning toward having endoscopic harvesting and most surgeons are leaning toward endoscopic harvesting."
People who are candidates for bypass surgery most likely will not be having a conversation with their surgeons about the method of vein removal, Alexander said. Data from the study indicate that "hospitals and surgeons have their preferred technique," and that technique most often is endoscopic harvesting.
"This paper will likely stimulate discussion among surgeons," Alexander said. "But it will not be easy to change standard practice. And it is difficult in our health system to shop around, and I'm not certain it's the right thing to do."
"We have a conundrum," said Dr. T. Bruce Ferguson, chairman of cardiovascular sciences at the East Carolina Heart Institute, a member of the research team. "A technique which is technically more difficult to do but is done more often because it is better for patients now has been linked to outcome in a way that suggests we need to figure out how to improve endoscopic vein harvesting."
The study disclosed "an association, not a direct cause-and-effect relationship," Ferguson said. "The dominos appear to be in a straight line, but we don't know if they are supposed to be that way or just appear to be that way."
There is no obvious solution to the conundrum, he said. "It is incumbent on the cardiac surgical community to determine how to impact the risk-benefit equation so that we eliminate the downside while making the upside even better," Ferguson said.
"Every cardiac surgical group in the country should pay particular attention to the vein harvesting procedure," he said. "We must evaluate these things on an individual patient basis."
Ultimate answers would come only from a large controlled trial with long-term follow-up, comparing results of bypass procedures done with veins removed by the two different methods, Alexander and Ferguson said.
Such a trial would be difficult to do and might raise ethical questions, Ferguson said. "And it would be years before we had results," Alexander added.
The reason for the difference in outcomes is unclear, he said. "The best hypothesis is that some damage is done to the vein in endoscopic harvesting," Alexander said. "What it is and how you might change it are unknown."
Coronary artery bypass surgery is described by the American Heart Association.