Study compares 'on-' and 'off-pump' procedures
By Steven Reinberg
THURSDAY, Aug. 17, 2017 (HealthDay News) -- Five years after heart bypass surgery, patients whose operation was done using a heart-lung pump lived longer than those whose surgeons didn't use the device, a new study finds.
Since the 1990s, two different approaches have been commonly used by heart surgeons to perform coronary artery bypass graft operations. Coronary artery bypass creates new routes for blood to flow to the heart because old routes are blocked by plaque in the artery. A piece of blood vessel is taken from another area of the body (often the leg) and used to "bypass" a blocked vessel going to the heart, according to the U.S. National Heart, Lung, and Blood Institute.
The two different ways to do this surgery have been referred to as "on-pump," assisted by a heart-lung machine, or "off-pump." Which procedure produces better results has been controversial, the researchers said.
"The heart-lung machine allows you to stop the heart so you can sew the grafts with no blood flowing through it," said senior researcher Dr. Frederick Grover, a professor of cardiac surgery at the University of Colorado.
This enables the surgeon to work on a heart that is fully exposed and not moving, he said.
When operations are done on-pump, surgeons are able to do more grafts. In off-pump surgery, the heart is a moving target as it continues to pump blood.
This report looks at the five-year outcomes of patients who had heart surgery as part of the U.S. Veterans Affairs trial of on-pump versus off-pump operations done from February 2002 through June 2007.
In this trial, more than 2,200 patients from 18 VA centers were randomly selected to receive either on-pump or off-pump heart surgery. They were assessed a year after their operation and then at five years.
Specifically, the researchers looked for major cardiac problems, including death from any cause, the need for new heart procedures or nonfatal heart attacks.
After a year, more patients who had an off-pump operation died or needed new procedures than patients who had on-pump surgery, Grover said.
Five years after surgery, the rate of death among those in the off-pump group was a little over 15 percent, compared with nearly 12 percent among those who had on-pump surgery, the researchers found.
That's a 28 percent higher risk of dying five years after surgery for the off-pump group, Grover said.
In addition, more people who had off-pump surgery had major cardiovascular problems than those who had on-pump operations -- 31 percent versus 27 percent, he said.
Grover's team also looked for other outcomes after five years, including death from heart disease and the rate of nonfatal heart attacks. The rates of these secondary outcomes appeared to be about the same for both groups, the researchers found.
Overall, "Off-pump did not look as good as on-pump," Grover said.
"Off-pump is not indicated except for certain patients who have issues, such as a heavily calcified aorta," he explained. That means there's a lot of plaque build-up in the artery. And, when a pump is used, the aorta has to be clamped. Clamping can cause plaque in the artery to break off and result in a blockage of the heart or brain, Grover said.
Other reasons to use off-pump include patients suffering from liver failure, he said.
The report was published Aug. 17 in the New England Journal of Medicine.
Dr. Joseph Sabik is chairman of the department of surgery at University Hospitals in Cleveland. He said, "Surgery is a technical thing, and a lot of the outcomes depend on how good your surgeon is, particularly, how experienced and technically able the surgeon is with the procedure they are doing."
Off-pump surgery is technically demanding, so one should have an experienced surgeon, Sabik said. He co-authored an accompanying journal editorial.
"If you select the patients properly, and the surgery is done by an experienced surgeon, then the results can be good," Sabik said.
Patients who need many grafts may fare better with on-pump surgery, Sabik said, "because you just can't do it as well as off-pump."
Elderly patients who may have had a stroke and only need two or three grafts probably do better off-pump, he said.
"Both are very good procedures," Sabik said. "The key is to have a surgeon experienced with both so that they can choose the right one for you."
For more on heart bypass surgery, visit the U.S. National Heart, Lung, and Blood Institute.
SOURCES: Frederick Grover, M.D., professor, surgery, University of Colorado, Aurora; Joseph Sabik, M.D., chairman, department of surgery, University Hospitals, Cleveland; Aug. 17, 2017, New England Journal of Medicine
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