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For patients undergoing elective coronary artery bypass grafting (CABG), using a radial artery graft versus a saphenous vein graft did not improve patency rates, a randomized trial showed.

At one year, the patency rate was 89% with each type of graft (P=0.82) among the more than 730 patients in the analysis, according to Steven Goldman, MD, of Southern Tucson VA Health Care System in Arizona, and colleagues.

There was still no significant between-group difference after adjustment for study site, target vessel, whether surgery was on or off pump, and smoking (OR 0.99, P=0.98), they reported in the Jan. 12 issue of the Journal of the American Medical Association.

Because long-term patency is an important question, they noted, the study has been funded for a five-year angiographic follow-up.

Most patients who undergo CABG receive a left internal mammary artery graft to bypass the left anterior descending coronary artery, and a saphenous vein graft for other vessels. The efficacy of using other arteries for grafting -- including the radial artery, which is the easiest to harvest -- is less clear.

Goldman and his colleagues conducted the randomized, controlled trial from 2003 to 2009 at 11 VA medical centers to compare radial artery versus saphenous vein grafts.

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 a radial artery or saphenous vein graft.

After randomization, 24 patients were excluded for various reasons, most commonly consent form issues (eight patients), destruction of the study site by Hurricane Katrina (six patients), and receipt of a single graft from the left internal mammary artery (five patients).

That left 733 patients who underwent CABG for a vessel with more than 70% stenosis, using either a radial artery or saphenous vein graft. Nearly all of the patients (99%) were male.

Surgeons performed most of the operations (88%) on pump.

The number of patients who received the assigned graft was higher in the saphenous vein group (367) versus the radial artery group (366).

For the purposes of the primary endpoint, a graft was considered occluded if there was 100% blockage at the origin, body, or distal site of the graft.

Although there was no between-group difference in the one-year patency rate, the researchers acknowledged that 100% occlusion occurred less frequently than expected, possibly resulting in the analysis being underpowered to detect a difference.

String sign (99% occlusion) was more common with radial artery grafts (8% versus 1%, P<0.001). So was severe stenosis of 75% to 100% (24% versus 16%, P=0.03).

"Despite similar patency rates, there was more disease in the radial artery grafts at one week and at one year. Although the explanation for this difference is not clear, there is clearly more spasm or string sign in radial artery grafts," Goldman and co-authors wrote. Additionally, they noted that "the radial artery can develop atherosclerosis and calcification, especially in patients with diabetes."

There were no significant between-group differences on any of the secondary endpoints, including one-week graft patency, MI, stroke, repeat revascularization, and death.

Surgical complications were generally similar with both types of grafts, although there were fewer hemorrhages requiring blood transfusions in the patients who received a radial artery graft (0.8% versus 3.3%, P=0.03).

There were no between-group differences in serious adverse events or intervention costs.

Researchers measured a minimal decrease in hand function at 12 months in the patients who received a radial artery graft.

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