When patients receive a coronary artery bypass graft, the surgery is traditionally done with the heart stopped and a heart-lung machine doing the work of the cardiopulmonary system. Referred to as on-pump CABG, the method was thought to be safer and better for long-term patient outcomes.
But a growing body of evidence indicates that on-pump CABG is not necessarily superior to the slightly younger off-pump CABG. Now, a new study by a group of Canadian researchers, the first to examine long-term outcomes, lends further support to that idea. Published Sunday in the New England Journal of Medicine, the analysis found no significant differences in five-year outcomes among patients who received on-pump and off-pump CABG.
“Our trial results indicate that both procedures are equally effective and safe,” the authors wrote.
CABG is the most common open-heart surgery done in the U.S. The procedure redirects blood flow to the heart for people with coronary heart disease, whose coronary arteries are sometimes completely clogged with the built-up plaque that can eventually cause a heart attack.
When a pump is used, CABG surgery-related mortality rates hover around 2%, the study noted. Another 5% to 9% of patients have a heart attack, stroke or renal failure. Other complications in both the short and long term could also be related to operational steps, such as cross-clamping the aorta, during on-pump procedures.
With off-pump CABG, also known as beating-heart surgery, surgeons can stabilize the heart to allow it to continue pumping and circulating blood during surgery.
The randomized, controlled trial was the first to examine the long-term outcomes of using or not using a pump during CABG. It looked at 4,752 patients aged 75 to 90 years at 79 hospitals from 19 countries from November 2006 through October 2011, half of whom underwent CABG on pump and half off.
Follow-ups conducted nearly five years after the surgery found “no significant difference” between the groups in terms of death, nonfatal strokes, heart attacks and kidney failure, and repeated procedures. The researchers also found no significant differences in costs or quality of life.
They called for further research into the impact of the surgery on patients with diabetes, after finding an apparent differential effect of the two approaches depending on whether a patient was diabetic.
Hospitals are starting to adopt off-pump procedures, albeit gradually. One estimate, from the American Heart Association in 2011, held that about 20% of surgeons nationwide use it.
For the vast majority of cases at Longview (Texas) Regional Medical Center, surgeons no longer stop the heart or crack open the breastbone to perform bypass surgery, said Dr. David Jayakar, a cardiothoracic surgeon at the community hospital. “For the bypass, we do a small cut on the left chest, without using the midline cut,” he said.
The shift to minimally invasive, off-pump grafts at Longview came about in part because about seven years ago the facility set its sights on building a top-notch heart program.
“Most of the valve surgeries and hybrid surgeries were going out of town” to facilities in Dallas and Houston, Jayakar said. Even under the overarching ambition to offer cutting-edge heart medicine, the switch from on-pump to beating heart surgery involved a “radical change,” he said.
The most recent guidelines, from December 2011, from the American College of Cardiology and the American Heart Association state that while on-pump CABG has become “the gold standard” in the U.S., that procedure is linked with various complications. Essentially, those groups conclude, the merits of on- and off-pump CABG vary with the patient and the surgeon's level of comfort.