Impact of clopidogrel plus aspirin versus aspirin alone on the progression of native coronary artery disease after bypass surgery: analysis from the Clopidogrel After Surgery for Coronary Artery DiseasE (CASCADE) randomized trial

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.

Keywords: clopidogrel; coronary artery disease; platelet aggregation.