JAMA: Surgeons may need to reconsider radial artery grafts for CABG
CABG surgery is commonly performed, with nearly 450,000 procedures completed during 2006 in the U.S. The success of the surgery depends on the long-term patency of the arterial and venous grafts.
Previously, arterial grafts were thought to be better conduits than saphenous vein grafts for CABG, according to background information in the article. The efficacy of the radial artery graft is less clear. The STS database has shown that more than 10,000 patients in the U.S. received radial artery grafts in 2008, suggesting that about 6 percent of patients undergoing CABG have radial artery grafts.
Lead author Steven Goldman, MD, of the Southern Arizona VA Health Care System and the University of Arizona Sarver Heart Center in Tucson, told Cardiovascular Business News that prior to the study, he and his colleagues had 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.
In the randomized controlled trial, Goldman and colleagues compared one-year angiographic patency of radial artery grafts versus saphenous vein grafts in 757 participants (99 percent men) undergoing elective first-time CABG. The trial was conducted from February 2003 to February 2009 at 11 Veterans Affairs medical centers. The left internal mammary artery was used to preferentially graft the left anterior descending coronary artery whenever possible; the best remaining recipient vessel was randomized to radial artery versus saphenous vein graft.
The primary outcome measured was angiographic graft patency at one year after CABG. The secondary outcomes included angiographic graft patency at one week after CABG, heart attack, stroke, repeat revascularization and death.
The analysis included 733 patients (366 in the radial artery group, 367 in the saphenous vein group).
The researchers found that there was no significant difference in one-year graft patency between radial artery (89 percent) and saphenous vein grafts (89 percent).
Also, they did not find any significant difference in one-week patency between patients who received radial artery grafts (99 percent) versus saphenous vein grafts (97 percent), or in the other secondary outcomes. There was no difference in the number and types of adverse events, including serious adverse events.
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 arterial grafts are superior.
“Although most clinicians assume that compared with vein grafts, arterial grafts have an improved patency rate, there are little multi-institutional prospective data on radial artery graft versus saphenous vein graft patency,” the authors wrote.
Goldman pointed to one previous Canadian study, which assessed the two conduits, but those researchers randomized the radial artery to the saphenous vein within the same patients (N Eng J Med 2004;351(22):2302-2309). In contrast, Goldman et al allowed the surgeons to randomize the best conduit for each patient.
The rates of radial artery grafts have been rising in the U.S. due to an enthusiastic belief that the technique improves patency, says Goldman, who adds that the “long-term consequences are still unknown.”
Because long-term patency remains an important question, the VA has funded Goldman et al to collect angiographic data for five years of follow-up on these patients to define chronic graft patency in this population.
In addition to the clinical considerations, the researchers examined the economic comparison between the two conduits, and found that there was no difference in the surgery costs, the cost to the patient and the cost to the U.S. healthcare system at one year, Goldman reported. "While the patients who receive saphenous vein grafts actually get released from the ICU sooner, the preparatory surgical costs for the radial artery conduit are more expensive, and compensate for the decreased hospitalization costs for the saphenous vein approach," he said. These cost considerations also will be assessed out to five years between the two procedures.