Single vs. Bilateral Internal Thoracic Artery Grafting
What are long-term (10-year) outcomes comparing bilateral to single internal thoracic artery grafting among patients undergoing coronary artery bypass graft (CABG) surgery in the ART (Arterial Revascularization Trial) study?
Patients with significant coronary artery disease undergoing CABG were randomly assigned to the use of bilateral internal thoracic artery (ITA) grafting (n = 1,548) versus single ITA grafting (n = 1,554). Both arterial grafts had to be placed to left-sided vessels in the bilateral graft group. Use of radial artery grafts was permitted to complete revascularization. The primary endpoint was death from any cause after 10 years. The secondary endpoint included composite of death from any cause, myocardial infarction, and stroke.
Over 3,100 patients were enrolled (1,548 patients underwent bilateral ITA grafting and 1,554 underwent single ITA grafting. In the intention-to-treat analysis at 10 years, there were no significant differences in rates of death (20.3% in the bilateral-graft group vs. 21.2 in the single-graft group; hazard ratio [HR], 0.96; 95% confidence interval [CI], 0.82-1.12; p = 0.62). There was also no difference in the composite outcome of death, myocardial infarction, or stroke (HR, 0.90; 95% CI, 0.79-1.03). About 14% of patients in the bilateral graft group received only a single ITA graft, and in the single-graft group, 21.8% of the patients also received a radial-artery graft.
There was no difference in death rates among patients receiving bilateral ITA grafting compared to single ITA grafting. The trials leave open the question of outcomes of multiple arterial grafts (radial artery and/or ITA) compared to single arterial graft.
Previous nonrandomized studies have suggested improved mortality and outcomes among patients with bilateral ITA grafting compared to the traditional approach of single ITA with saphenous vein grafting. The ART trial is a landmark trial of predominantly male patients undergoing CABG and reported 10-year mortality data. The intention-to-treat analysis did not show a difference in mortality between patients who received a single ITA versus those who received bilateral ITA. The trial is limited by significant cross-over rate (14% of patients in the bilateral graft group only received a single graft), highlighting the need for surgical expertise for bilateral ITA. In addition, one fifth of the patients received radial artery grafting in the single ITA group, which may have confounded the potential difference between the cohorts. There was a 20% reduction in mortality in favor of multiple arterial grafting versus single arterial grafting in the as-treated group. It is important to note that there was no signal for excess sternal wound complications in the bilateral ITA group. Results of the ROMA (Randomized comparison of the clinical outcome of single versus multiple arterial grafts) trial are eagerly awaited and may potentially change practice. But for now, strict use of bilateral ITA is not superior to single ITA grafting.
Keywords: Cardiac Surgical Procedures, Coronary Artery Bypass, Coronary Artery Disease, Mammary Arteries, Myocardial Infarction, Myocardial Revascularization, Radial Artery, Saphenous Vein, Stroke, Vascular Diseases
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