Coronary artery bypass graft (CABG) surgery has undergone many changes, and continues to evolve. Some of the debates currently being played out within clinical practice include radial artery vs. saphenous vein grafts, open vs. endoscopic vein harvesting, CABG on- vs. off-pump and how best to reduce CABG-related stroke.
Radial artery vs. saphenous grafts
The Society of Thoracic Surgeons database indicates that more than 10,000 patients in the U.S. received radial artery grafts in 2008, about 6 percent of total CABG patients. However, the efficacy of radial artery grafts is unclear, based on the current literature.
In a recent study of 733 VA patients from February 2003 to February 2009, Steven Goldman, MD, of the Southern Arizona VA Health Care System and the University of Arizona Sarver Heart Center in Tucson, and colleagues found that the use of a radial artery graft compared with a saphenous vein graft did not result in improved angiographic patency at one year—89 percent for each (JAMA 2011;305(2):167-174).
Goldman says that prior to the study, he and his colleagues hypothesized that the radial artery would have a superior patency because surgeons have likened arterial grafts to the internal mammary artery, which has a better graft patency than veins. While he and his colleagues were surprised by the findings, Goldman says that there has not been much clinical data to support the assumption that radial arterial grafts are superior.
Prior to the study, some surgeons had already begun to reduce utilization of radial artery grafting due to sub-optimal in-practice outcomes. "The JAMA study validates my experience after 25 years in clinical practice, during which time radial artery grafting has experienced two periods of gaining and losing popularity," explains Daniel M. Goldfaden, MD, a cardiothoracic surgeon at HCA's Redmond Regional Medical Center in Rome, Ga. "In both instances, the conduit lost favnor because of high early failure rates."
Since the most recent resurgence of radial artery use, which began about eight to 10 years ago because of new drug protocols to control spasm, Goldfaden and colleagues have essentially discontinued the use of radial grafting, reserving those arteries for patients who do not have another conduit or, occasionally, in "younger patients with a major graft in an artery that we cannot bypass with an internal mammary," he says.
Joseph F. Sabik III, MD, chairman of thoracic and cardiovascular surgery at Cleveland Clinic, agrees that radial artery grafts can be effective in the right patient. "The patency with radial artery grafts is best when used to bypass an artery that is totally blocked or has severe stenosis, as the guidelines suggest, while it's not as effective to bypass an artery with moderate stenosis," he says.
"There also is significantly more morbidity in harvesting radial grafts," states Michael J. Mack, MD, medical director of cardiovascular surgery for the Baylor Healthcare System in Plano, Texas. "Due to the lack of proven benefits, we use far fewer radial artery grafts than we did even three to four years ago."
An economic analysis by Goldman et al found no significant difference between the two conduits in the cost of surgery, the cost to the patient or the cost to the U.S. healthcare system at one year. "The radial artery graft cohort hospitalization costs were slightly higher than the saphenous vein graft cohort because surgical preparatory costs for the radial artery conduit were more expensive, even though saphenous vein graft recipients were released from the ICU earlier," Goldman says.
However, because long-term patency remains an important clinical question, the VA has funded Goldman and his colleagues to collect angiographic data for five years of follow-up on these patients to define chronic graft patency. The cost considerations also will be assessed.
Open vs. endovascular vein harvesting
While saphenous vein grafting is still the most common conduit, it has traditionally necessitated open harvesting, requiring linear incisions along the course of the vein, which has led to various complications. Endoscopic vein harvesting (EVH), a procedure developed to eliminate the need for the long incisions associated with open harvesting, has been shown to reduce the risk of wound infection and other complications, lessen postoperative pain, shorten the patient's length of stay in the hospital and lead to greater patient satisfaction. However, less is known