Radial artery bests saphenous vein grafting and RITA in patients undergoing CABG: 15-year follow-up RAPCO trial

The findings from the trial showed absolute risk reductions of 9% and 13%, respectively, for MACE with radial artery compared to RITA and saphenous vein grafting. The findings were presented at the Scientific Sessions 2022 of the American Heart Association (AHA).

Several previous studies have shown the benefit of radial artery grafts in CABG. Still, the data from the RAPCO trial are the first to come from a single trial and represent some of the most extended follow-ups, with some patients being randomized nearly before 25 years.

David Hare and the team conducted the randomized, parallel trial to evaluate a radial artery bypass graft versus a free right thoracic internal artery bypass graft undergoing CABG surgery. A two-part analysis compared radial artery grafting to using the free RITA in patients less than 70 years or saphenous vein grafting in patients 70 or older.

The left internal thoracic artery to the left anterior descending artery was the standard of care for all the patients in the study. For this purpose, 394 participants undergoing CABG were enrolled; 198 were randomized to a radial artery bypass graft, and 196 were given a free right internal thoracic artery bypass graft. The 15-year clinical follow-up data were available except for one patient in the radial artery group.

The study led to the following findings:

• In those who received radial artery grafting, the MACE rate was significantly lower over 15 years (39.4% vs 48.5%), driven by a trend in lower all-cause mortality (22.2% vs 30.1%).
• For the RAPCO-SV side of the trial, 225 patients (mean age 73 years; 45% diabetes) were randomized; 113 received radial artery and 225 received saphenous vein grafting. The 15-year clinical data were available except for one saphenous vein graft group patient.
• Over 15 years, the MACE rate was remarkably lower for radial artery grafting(60.2% vs 73.2%), which was also driven by lower mortality rates (52.2% vs 63.4%).
• Both analyses observed no differences in the individual secondary endpoints of MI or repeated coronary revascularization.
• Prespecified subgroup analyses looking at age, sex, and diabetes status were all consistent with the main findings. However, there was a trend toward benefit with radial artery grafting for females in the RAPCO-SV results.

The radial artery bypass graft versus a free right internal thoracic artery bypass graft among patients undergoing CABG was associated with improved outcomes. Also, there were numerically lesser deaths in the radial artery bypass graft group.

"Further studies are required to establish if an instrumented radial artery can serve as a satisfactory bypass conduit," the authors concluded.

Reference:

Hare DL. Radial artery patency and clinical outcomes study – RAPCO: the 15-year RCT clinical outcomes comparing radial artery with right internal thoracic artery or saphenous vein. Presented at: AHA 2022. November 6, 2022. Chicago, IL.