Radial Artery Coronary Bypass Conduit
Abstract & Commentary
Synopsis: Using a radial raft, as opposed to a vein graft as the second bypass in patients receiving a LITA to the LAD, resulted in less late mortality without a lot of quality data to support it.
Source: Zacharias A, et al. Circulation. 2004;109: 1489-1496.
The survival benefit of using the left internal thoracic artery (LITA) to bypass the left anterior descending coronary artery (LAD), as compared to a saphenous vein graft, has been demonstrated. However, the best second choice is unclear, so Zacharias and colleagues from the Medical College of Ohio tested the hypothesis that a radial artery graft would be superior to a vein graft. This was retrospective observational analysis of their experience using propensity watching to overcome confounding effects. Between January 1996 and December 2002, there were 3161 isolated multigraft LITA-LAD bypass patients, of whom 1292 (41%) received a radial graft to the second vessel vs 1869 (59%) who received a vein. Since there were clinical differences between the 2 groups, 925 radial patients were propensity matched to vein patients. Perioperative outcomes were the same for both groups including death (1%). Cumulative 6-year survival was 92% for radial patients and 87% for vein patients (risk ratio, .68; P < .03). Repeat catheterization and revascularization rates were similar, but vein graft failure was higher than radial graft failure (41% vs 29%; P = .04). However, LITA patency was best with a failure rate of 6%. All LITA grafts were to the LAD. Chockolingam et al concluded that using a radial raft, as opposed to a vein graft as the second bypass in patients receiving a LITA to the LAD, resulted in less late mortality.
Comment by Michael H. Crawford, MD
Based upon the improved survival of patients with LITA to LAD grafts, the concept of an all-arterial coronary bypass operation has emerged without a lot of quality data to support it. Although retropective, this is a well-done study that attempts to answer the limited question of whether the radial artery or a vein graft is the best second graft after a LITA to LAD. Using several statistical manipulations to match patients in a large database, the results show improved survival with the radial graft. These results parallel those of studies comparing using the right ITA vs a vein graft for the second vessel. However, now that the routine use of calcium blockers has eliminated the problem of radial artery spasm, there are several perceived advantages of the radial artery vs bilateral ITA grafts: 1) radials are larger; 2) easier to prepare; 3) can be harvested simultaneously with the LITA; 4) can reach remote arteries better than RITA pedicle grafts; and 5) decrease the incidence of sternal wound infection as compared to bilateral ITAs. Unfortunately, there has not been a direct comparison of the 2 all arterial approaches. Also, there is the issue of what to do for the third graft: 1) a piece of left over radial; 2) ITAs and a radial; 3) LITA, radial and an abdominal vessel (gastroepiploic, splenic); or 4) a vein. The use of a vein would increase the likelihood of a graft failure, so many prefer an all-arterial approach when feasible. This study lends more credence to this concept, but a prospective randomized trial would be more convincing.
Michael H. Crawford, MD, Professor of Medicine, Associate Chief of Cardiology for Clinical Programs, University of California San Francisco, is Editor of Clinical Cardiology Alert.