The role of vessel wall physiology in predicting coronary bypass graft patency

Text The phase one results from the randomized Radial artery versus Saphenous Vein Patency (RSVP) trial are published in the current issue of the Journal [1]. Fifty-two patients had quantitative angiography with Thrombolysis in Myocardial Infarction (TIMI) flow assessment, approximately 3 months after coronary bypass graft surgery. A subset of 7 patients had in-vivo assessment of graft flow and vessel wall physiology, using intravascular Doppler ultrasound and pharmacologic manipulation. The investigators found that 11% of radial artery (RA) grafts had either a greater than 50% stenosis or diffuse narrowing (string sign), no RA was completely occluded, 5% of long-saphenous veins (LSV) were completely occluded, and the remaining RA or LSV grafts were perfectly patent. RA grafts were found to have intact endothelial function at 3 months post-operatively, whereas LSV grafts did not. Although flow volumes were similar in both conduits, the size match of conduit-to-target vessel was better with RA grafts. Hence, the investigators concluded that the RA is a more physiologic conduit for coronary bypass surgery.