Coronary bypass surgery patients who received a radial artery as their second bypass conduit had significantly better 10-year survival than did patients who received a saphenous vein graft in a combined analysis of more than 1,000 randomized patients who had originally been enrolled in any of five independent studies.
“This is the first report of a survival benefit for CABG [coronary artery bypass grafting] using multiple arterial conduits based on randomized data,” Mario F.L. Gaudino, MD, said at the joint scientific sessions of the American College of Cardiology and the World Heart Federation. The meeting was conducted online after its cancellation because of the COVID-19 pandemic.
Dr. Gaudino acknowledged several limitations of the finding. First, the analysis included studies that enrolled patients during 1997-2009 in five diverse sites worldwide and, therefore, involved varying surgical methods. Second, the sample size was “relatively low and underpowered, even after 10-year follow-up.” And third, the survival analysis was post hoc, although the statistically significant 27% relative reduction in mortality during follow-up with radial artery bypass, compared with saphenous vein bypass, was fully consistent with both the primary endpoint of the five studies and also with the combined hard endpoint of death and myocardial infarction.
The primary outcome of all-cause death, MI, and repeat revascularization also fell by a relative 27% with radial artery bypass, compared with saphenous vein bypass, and the combined rate of death and MI fell by 23% with radial artery bypass, both statistically significant differences, reported Dr. Gaudino, professor of cardiothoracic surgery at Weill Cornell Medicine, New York.
“The overall message is that radial bypass is associated with better long-term outcomes and potentially better survival,” he concluded.
The left interior thoracic artery (also known as the left internal mammary artery) is well established as the primary CABG conduit, usually used for bypassing the left anterior descending coronary artery, but when a second conduit is needed, several options exist: a saphenous vein, the left radial artery, or possibly the right internal thoracic artery (RITA) as a different arterial option.
Dr. Gaudino claimed that his new results placed the left radial artery clearly superior to the RITA as the second arterial conduit of choice for CABG. Not only does the RITA lack a similar efficacy evidence base from randomized trials, but the method poses a higher risk for surgical wound infections, he noted. The most recent society recommendations on conduit choice for CABG, issued less than 2 years ago by the European Society of Cardiology and European Association for Cardio-Thoracic Surgery, tapped the left radial artery as a level I recommendation over a saphenous vein graft when patients have high-grade coronary stenosis, while the RITA trailed as a level IIa recommendation specified only for patients with a low risk for sternal-wound infection.
“This was a great study that brings home the point that, in general, the radial artery is better than a saphenous vein graft,” commented Marc R. Moon, MD, a designated discussant and a professor of surgery and chief of cardiac surgery at Washington University, St. Louis.
The long-term follow-up that Dr. Gaudino reported came from extended, patient-level data collection for all 1,036 patients included in the original RADIAL (Radial Artery Database International Alliance) analysis of 5-year outcomes and reported in 2018. Dr. Gaudino and his associates tracked down survival information for all those patients, with outcome records out to at least 10 years for 91% of the original participants and with a mean follow-up that was also 10 years. The prior 2018 report based on 5-year results had also shown a statistically significant reduction in the primary endpoint with radial artery grafting, but at that point, follow-up had not yet collected enough mortality endpoints to produce a statistically significant between-group difference in death from any cause, a shortcoming that may have limited the ability of the prior report to influence U.S. practice.
“In the United States, there has been very little uptake of multiarterial grafting,” commented Frederick G.P. Welt, MD, a designated discussant, interventional cardiologist, professor of medicine, and associate chief of cardiovascular medicine at the University of Utah, Salt Lake City. The results from several earlier studies did not show much benefit for graft patency using radial arteries, but more recently clinicians have made advances in radial artery harvesting methods, implantation techniques, and adjunctive medications including antispasmodic treatments, Dr. Welt noted. Improved methods for using radial artery grafts and the risk of wound infection with RITA grafts were summarized in an editorial that accompanied the report of the 5-year RADIAL findings.
Dr. Welt said that, among the new findings reported by Dr. Gaudino, “the mortality effect is the most impressive.” Despite the limitations of the post hoc survival analysis, the reduced mortality finding is “nevertheless really important. The patient-level data lend it more credence.”
The study received no commercial funding. Dr. Gaudino had no disclosures. Dr. Moon has been a consultant to Medtronic. Dr. Welt has been an adviser to Medtronic.
SOURCE: Gaudino MFL et al. ACC 20, Abstract 410-11.