Midterm endothelial function and remodeling of radial artery grafts anastomosed to the aorta

Background: The purpose of this study was to elucidate the midterm endothelium-dependent vasodilatory capacity of radial artery grafts anastomosed to the aorta, as well as their morphometric evolution with the time. Methods: Five years after surgery we evaluated the response of aorta-anastomosed radial artery grafts to the endovascular infusion of acetylcholine in 11 of the first 61 patients operated on at our institution, and we compared it to the response with that of internal thoracic artery grafts. Moreover, the first 20 patients who had a perfect radial artery graft on angiography at 1 year were restudied at 5 years and subjected to a comparative analysis of the diameters of the radial artery graft and the grafted coronary arteries. Results: At midterm angiography, dilation of the 2 types of grafts was similar in response to acetylcholine administration (radial artery, from 2.61 ± 0.39 to 2.90 ± 0.34 mm; internal thoracic artery, from 2.68 ± 0.21 to 2.93 ± 0.27 mm; P = .01 for both). The diameters of aorta-anastomosed radial artery grafts and grafted coronary arteries increased between both 1 and 5 years according to angiographic studies (radial artery grafts, from 2.08 ± 0.45 to 2.54 ± 0.53 mm; grafted coronary arteries, from 1.92 ± 0.47 to 2.18 ± 0.41 mm; P < .001 for both), but the increase was greater for the radial artery grafts (P < .001). Conclusions: Aorta-anastomosed radial artery grafts maintain an appreciable capacity for endothelium-dependent vasodilatation 5 years after implantation and undergo a progressive increase in luminal diameter with time. These observations contradict the presumed tendency for progressive fibrous intimal hyperplasia to develop in radial artery grafts.