904 Comparing early and late angiography to determine progression of graft disease between the radial artery and saphenous vein graft after coronary artery bypass surgery: Insights from the Radial Artery Patency Study (RAPS) - a multi-centered, randomized control trial

Abstract

Graft patency is an important determinant of long-term survival after coronary artery bypass surgery (CABG). Differences between conduit characteristics of arteries and veins can dictate progression of graft disease and significantly impair long term patency. We present and compare early and late patency rates, and the progression of disease between the radial artery and saphenous vein (SVG), in the subset of patients from the Radial Artery Patency Study (RAPS) that have undergone both early and late angiography. 561 patients less than 80 years of age undergoing primary isolated non-emergent CABG with 3-vessel disease and estimated ejection fraction >35% were initially enrolled across 13 centers. The anterior circulation was bypassed using the left internal mammary artery. Within-patient randomization was performed for the study grafts; the Radial Artery was randomized to either the right or circumflex territory and the study SVG was used for the opposing region. Protocol directed angiographic follow-up was at 1 and 5 years. The primary objective was to determine the change in TIMI flow between early and late angiography for each study graft. The secondary objective was to determine in grafts with TIMI 3 flow, the progression of graft disease (from < 30 % to ≥ 30%) in the graft body, proximal or distal anastomoses. 440 and 234 patients underwent early and late angiography respectively. 217 patients underwent both angiographies (Early-10 ± 3 months; Late-7.5 ± 1.3 years following surgery, mean+/−standard-deviation). Early functional graft occlusion (lack of TIMI 3 flow) for the Radial was 7.4% (16/217) vs. 12.9% (28/217) in the SVG,P = 0.09, while late functional occlusion was 11.5% (25/217) vs. 17.5% (38/217), P = 0.12, respectively. Over 7 years, the change in functional occlusion for the Radial and SVG was 4.1% and 4.6%, respectively, P = 0.80. Of the Radials that were initially TIMI 3 at year 1, 94.0% (189/201) vs. 92.6% (175/189) of SVGs remained TIMI 3, P = 0.58, while 4.5% of the Radials (9/201) vs. 6.3% of SVGs (12/189), P = 0.43, progressed to TIMI 0 (Table-1).Tabled 1 Of the initial proximal (Px) and distal (D) anastomosis sites that had < 30% stenosis, progression of disease to ≥30% was similar in both radial and SVG over 7 years. For the graft body, 94.1% of Radials (174/185) compared to 84.7% SVGs (144/170) remained the same, P = 0.004, while 5.9% of Radials (11/185) vs. 15.3% of SVGs (26/170), P = 0.004 progressed to stenosis ≥30%. The increase in the number of lesions in the 31-70% category between early and late angiography were similar between Radial and SVG for proximal anastomoses. New distal anastomotic lesions were decreased in the SVGs [Radial 4.2%, (8/189) vs. SVG 0.6%, (1/175), P = 0.03], while there were fewer new graft body stenoses in the Radials [Radial 3.2%, (6/189) vs. SVG 9.7%, (17/175), P = 0.01]. The increase in significant stenosis(≥30%) in any graft segment was similar for the Radial and SVG [Radial 12.7%, (24/189) vs. SVG 16.0%, (28/175), P = 0.37]. Over 7 years, the SVG had significantly greater disease progression in the graft body compared to the radial artery. The radial artery may be superior to the SVG due to decreased graft body atherosclerosis resulting from differential graft biology.