Bypass Patients Fare Equally Well With or Without Heart-Lung Machine
Three studies find no differences in outcomes, even for the frail or elderly
By E.J. Mundell
MONDAY, March 11 (HealthDay News) -- Coronary artery bypass surgeries are one of the most common heart operations, and three new studies find it makes little difference whether they are done with or without the aid of a heart-lung machine.
Patients having so-called "off-pump" (no heart-lung machine) bypass procedures fared equally well as those who got the "on-pump" version, even if they were very sick or elderly, the trio of studies found. On the other hand, patients who had bypass with the aid of a heart-lung machine also had no evidence of a higher risk of lowered mental function afterwards, something that prior studies had suggested might be a concern.
The studies were presented Monday in San Francisco at the annual meeting of the American College of Cardiology (ACC).
Bypass surgery involves the transplant of a vessel sourced from elsewhere in the patient's body to "bypass" a clogged artery servicing the heart. The procedure can be done while the heart is temporarily stopped and the patient is placed on a heart-lung machine, or it can be done in an "off-pump" mode, in which the surgeon lifts the still-beating heart out of the chest cavity to perform the necessary grafts.
Initially, experts worried that off-pump bypass might be too risky, especially for more frail patients. But the three new studies suggest otherwise.
One comparison study, the largest yet performed, was led by Dr. Andre Lamy of the division of cardiac surgery at McMaster University in Hamilton, Ontario. The trial involved more than 4,750 patients from 79 centers across 19 countries, who were scheduled to undergo bypass.
After one year of follow-up, the team found no significant difference in rates of death, stroke, heart attack or new kidney failure for people who got the off-pump procedure (12.2 percent) and those who got the on-pump version (13.3 percent).
"I think surgeons around the world who are experienced off-pump [surgeons] can do off-pump surgery as an option without any difficulty or any added risk for their patients," Lamy told reporters at an ACC press briefing held Monday.
Patient quality of life, including any issues with thinking/memory, also improved for most patients, regardless of the technique used. "The quality of life of patients increased after cardiac surgery; there's no difference between the two techniques," Lamy said.
Surgeon experience might be key, however: All the surgeons enrolled in the trial had at least 100 hours experience in the bypass method they used, the researchers said.
But what if the patient is elderly or very sick and at higher risk? Two other studies suggest that opting for "off-pump" doesn't matter there, either.
One study, conducted in Germany with more than 2,500 patients 75 or older, found no significant difference in rates of such events as death, stroke, heart attack or need for repeat heart procedures within a month of the bypass, regardless of the strategy used.
Speaking to reporters at the press briefing, lead author Dr. Anno Diegeler, head of cardiovascular surgery at Heart Center Bad Neustadt, noted that a 12-month follow-up also showed no difference.
"Even for this elderly patient, we do not see a major benefit of one of the techniques versus the other," he said.
So which type of patient might be best suited to which procedure?
Diegeler said that, at his center, "those patients who are over 75 years old go to off-pump more than to on-pump, those patients with general vascular disease -- because we know that their stroke rate is much higher -- they go to off-pump as well."
The studies led by Lamy and Diegeler are also being published online Monday in the New England Journal of Medicine.
A third trial, this one led by Dr. Jan Hlavicka, a heart surgeon at Charles University in Prague in the Czech Republic, looked at outcomes for 206 frail patients deemed to be at especially high risk who underwent one of the two procedures.
This time, off-pump bypass even seemed to have an edge on the on-pump version, with 9.2 percent of the patients experiencing negative cardiovascular events within a month of the operation, compared to nearly 21 percent of those who got the on-pump procedure.
Two experts in the United States said the findings reflect current practice.
"Elderly patients and other patients previously deemed to have increased risk for coronary bypass surgery are now routinely operated on with reduced risk and improved results in contemporary cardiac surgical practice," explained Dr. L. Michael Graveer, chief of adult cardiac surgery at Long Island Jewish Medical Center in New Hyde Park, N.Y.
And while off- and on-pump methods can deliver "equivalent outcomes," he stressed that "it is very important for the cardiac surgical team to have experience in both techniques in order to offer minimal risk and optimal results."
Dr. Scott Schubach, chair of the department of thoracic and cardiovascular surgery at Winthrop-University Hospital in Mineola, N.Y., agreed.
"Both techniques are important and can be used in appropriate clinical settings," he said. "Indications for standard on-pump versus off-pump procedures vary depending on specific patient risk factors and are subject to the surgeon's judgment."
Findings from studies that have only been presented at medical meetings, such as the trial led by Hlavicka, are typically considered preliminary until published in a peer-reviewed journal.
Find out more about coronary artery bypass surgery at the American Heart Association.
SOURCES: Scott Schubach, M.D., chair, department of thoracic and cardiovascular surgery, Winthrop-University Hospital, Mineola, N.Y.; L. Michael Graveer, M.D., chief, adult cardiac surgery, Long Island Jewish Medical Center, New Hyde Park, N.Y.; March 11, 2013, American College of Cardiology news conference with: Andre Lamy, M.D., division of cardiac surgery, McMaster University, Hamilton, Ontario, Canada, and Anno Diegeler, M.D., head of cardiovascular surgery, Heart Center Bad Neustadt, Germany