Key Points:
- Recent guidelines have supported the use of arterial grafts over venous grafts in coronary artery bypass grafting (CABG), but there has yet to be a single randomized trial examining long-term cardiovascular outcomes with these different grafting methods.
- In the RAPCO study, patients undergoing CABG were randomized to either a) radial artery (RA) grafting versus right internal thoracic artery (RITA) grafting or b) radial artery (RA) grafting versus saphenous vein grafting (SVG). The primary outcome of interest was MACE, a composite of cardiovascular mortality, acute MI, and revascularization.
- RA grafting was superior to both RITA and SVG grafting over 15 years of follow-up.
While there has been a plethora of observational evidence supporting the use of arterial grafts (such as radial artery grafts) over saphenous venous grafts in CABG, there has yet to be a large-scale RCT comparing the two strategies long-term. In a breaking presentation at the 2022 AHA Scientific Sessions today, Dr. David Hare (University of Melbourne) and his team presented their study: “Radial Artery Patency and Clinical Outcomes Randomized Trials – The 15-Year Clinical Outcomes Comparing Radial Artery with Right Internal Thoracic Artery or With Saphenous Vein Grafting,” or the RAPCO trial.
The RAPCO study (NCT00475488) was a singer-center randomized clinical trial conducted in Melbourne, Australia which evaluated the effects of radial artery (RA) grafting against both right internal thoracic artery (RITA) and saphenous vein grafting (SVG) in patients undergoing CABG. The inclusion criteria comprised any adults presenting for CABG without any associated procedures, requiring more than 1 graft; relevant exclusions included chronic HF, BMI > 35, acute cardiogenic shock, or associated malignancy. There were two separate comparison arms of the trial: the first was RA vs RITA grafting, and the second was RA vs SVG grafting. A total of 394 patients were randomized in the RA vs RITA comparison; the mean age was 59, and 10% of patients were female. A total of 225 patients were randomized in the RA vs SVG comparison; the mean age was 73, and 19% of patients were female.
The primary outcome was 15-year MACE (CV mortality, AMI, and revascularization), which was reduced in the RA group compared to both RITA (HR 0.74, 95% CI 0.55-0.97; p=0.04) and SVG (HR 0.71, 95% CI 0.52-0.98; p=0.04). The prespecified subgroup analyses of age, sex, and diabetes were not significant for any interaction in either comparison arm.
When discussing the clinical implications of the study at AHA, Dr. Hare stated: “The is the first single-trial RCT demonstrating better clinical outcomes using RA grafting compared to both RITA and SVG…all isolated CABG operations should consider using a radial artery graft unless there is a specific contra-indication.”