Impact of Clopidogrel Plus Aspirin Versus Aspirin Alone on the Progression of Native Coronary Artery Disease After Bypass Surgery

Abstract

Background— The effects of dual antiplatelet therapy with aspirin and clopidogrel on the progression of native coronary artery disease after coronary artery bypass grafting are unknown. Methods and Results— In the Clopidogrel After Surgery for Coronary Artery DiseasE (CASCADE) trial, a total of 113 patients were randomized to receive aspirin plus clopidogrel or aspirin plus placebo for 1 year after coronary artery bypass grafting. In this secondary analysis, the 92 patients who underwent preoperative and 1-year postoperative angiograms at 2 centers had each of their coronary stenoses graded serially by using 6 thresholds (grade 0 [0%–24%], grade 1 [25%–37%], grade 2 [38%–62%], grade 3 [63%–82%], grade 4 [83%–98%], and grade 5 [99%–100%]). We compared the incidence and degree of evolving coronary artery disease between the 2 treatment groups. A total of 543 preoperative stenoses and occlusions were quantified and followed. At 1-year postoperatively, there were 103 evolving (94 worsened, 9 improved) and 22 new lesions. The right coronary artery territory and sites proximal to a graft were more commonly associated with worsening coronary artery disease ( P ≤0.02). There were no differences in clinical events between treatment groups, and the proportion of patients with evolving or new lesions was also similar (70% versus 74%, aspirin–clopidogrel versus aspirin–placebo, respectively; P =0.8). However, in evolving or new lesions, the mean grade change (1.1±1.0 versus 1.6±1.1, respectively; P =0.01) and the proportion of new occlusions (7% versus 22%; P =0.02) were lower in the aspirin–clopidogrel group. Conclusions— The addition of clopidogrel to aspirin correlates with less worsening of native coronary artery disease 1 year after coronary artery bypass grafting. These findings may help guide post–coronary artery bypass grafting antiplatelet therapy. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00228423.