Comparison of Outcomes and Costs Associated With Aspirin ± Clopidogrel After Coronary Artery Bypass Grafting

Optimal antiplatelet therapy after coronary artery bypass graft (CABG) surgery remains controversial. This study evaluated the role of dual antiplatelet therapy using aspirin and clopidogrel (DAPT) versus antiplatelet therapy using aspirin only (ASA) on post-CABG clinical outcomes and costs. In the Department of Veterans Affairs Randomized On/Off Bypass (ROOBY) trial, clopidogrel use after CABG was prospectively collected beginning in year 2 of this study to include 1,525 of the 2,203 original ROOBY patients who received aspirin after CABG. Discretionarily, surgeons after CABG administered either DAPT or ASA treatments. The ROOBY trial's primary 30-day composite (mortality or perioperative morbidity), 1-year composite (all-cause death, repeat revascularization, or nonfatal myocardial infarction), and costs were compared for these 2 strategies. Of the 1,525 subjects, 511 received DAPT and 1,014 received ASA. DAPT subjects, compared with ASA subjects, had lower rates of preoperative left ventricular ejection fraction of ≥45% (78.8% vs 85.7%, p <0.001), on-pump CABG (36.6% vs 57.1%, p = 0.001), and endoscopic vein harvesting (30.0% vs 42.8%, p <0.001). ASA patients were more likely to have earlier aspirin administration and receive 325 versus 81 mg dosages. The 30-day composite outcome rate was significantly lower for DAPT patients compared with ASA patients (3.3% vs 7.1%, p = 0.003), but the 1-year composite outcome was equal between the 2 groups (12.0% vs12.0%, p = 1.0). At 1 year, there were no cost differences between the 2 groups. Propensity analyses did not significantly alter the results. In conclusion, DAPT appeared safe and was associated with fewer 30-day adverse outcomes than aspirin only and with no 1-year outcome or cost differences.