Tread cautiously with this trial
With a median follow-up of 10 years after coronary artery bypass grafting (CABG), patients who received a radial artery graft rather than a saphenous vein graft as a second conduit were less likely to experience death, MI, or repeat revascularization, according to pooled data from five randomized trials.
Dr. Mario F.L. Gaudino
The same result from the same set of data was produced after a median of 5 years, but the longer follow-up provides a more compelling case for the superiority of the radial artery graft, according to the authors of this meta-analysis, led by Mario F.L. Gaudino, MD, professor of cardiothoracic surgery at Weill Cornell Medicine, New York.
For the primary composite endpoint of death, MI, or repeat revascularization, the favorable hazard ratio at 5 years corresponded to a 33% risk reduction (HR, 0.67; P = .01), according to the previously published results (Gaudino M et al. N Engl J Med. 2018;378:2069-77).
The new data at 10 years show about the same risk reduction for the primary endpoint, but with more robust statistical significance (HR, 0.73; P < .001).
More importantly, because of the greater number of events by 10 years, the advantage of radial artery graft for the secondary composite outcome of death or MI has now reached statistical significance (HR, 0.77; P = .01).
In addition, there was a 27% reduction in risk of all-cause mortality (HR, 0.73; 95% confidence interval, 0.57-0.93) at 10 years associated with the radial artery graft. But this was not a prespecified endpoint, and so this is a hypothesis-generating post hoc finding.
The data was drawn from five randomized trials with a total of 1,036 patients. When used as an additional conduit to an internal thoracic artery in CABG, radial artery grafts relative to saphenous vein grafts were associated with a lower but nonsignificant risk of adverse outcomes in all five trials.
The advantage of radial artery grafts in the meta-analysis at 5 and now 10 years supports a series of observational studies that have also claimed better results with radial artery grafts.
The analysis was published July 14 in JAMA with essentially the same outcomes reported at the joint scientific sessions of the American College of Cardiology and the World Heart Federation in March.
However, a editorial that accompanied this meta-analysis in JAMA raised fundamental questions about revascularization.
Dr. Steven E. Nissen
“Intuitively, high-severity coronary lesions with significant ischemic burden, poor collateralization, and significant myocardium at risk may benefit from a durable revascularization option,” observed the editorial coauthors, Steven E. Nissen, MD, and Faisal G. Bakaeen, MD, both of the Cleveland Clinic. However, they cautioned that there is no definitive evidence that “any revascularization procedure reduces cardiovascular morbidity or mortality in patients with anatomically and physiologically stable coronary artery disease.”
They called the 10-year outcomes from the meta-analysis “the best available long-term data on the potential value of using the radial artery as a bypass conduit,” but warned that no randomized trial has confirmed that two or more conduits are superior to a single internal thoracic artery in CABG to for preventing death and major adverse cardiovascular events.
Such a trial, called ROMA, is now underway (Eur J Cardiothorac Surg. 2017;52:1031-40), but results are not expected until 2025.
In the meantime, placement of second conduits remains common in CABG procedures, about 400,000 of which are performed each year in the United States. According to Dr. Gaudino, there are indications and contraindications for second conduits, but radial artery should be the preferred standard when these are considered.
“Our data indicate that the radial artery graft should be used to complement the left internal thoracic artery in all patients who meet the indications for radial artery grafts,” he explained in an interview.
“Unfortunately, at the moment radial artery grafts are used in less than 10% of CABG cases in the U.S.,” he reported. “Hopefully, our data will lead to a larger use of this conduit by the surgical community.”
Dr. Gaudino, the principal investigator, reported no potential conflicts of interest relevant to this study.
SOURCE: Gaudino MFL et al. JAMA. 2020;324:179-87.