Use of Aspirin and Clopidogrel After Coronary Artery Bypass Graft Surgery

OBJECTIVE: To evaluate the evidence for the use of dual antiplatelet therapy (DAPT) with aspirin and clopidogrel following coronary artery bypass graft (CABG) surgery. DATA SOURCES: Literature was accessed through PubMed (1950-November 2011), EMBASE (1976-November 2011), and the Cochrane databases using the terms clopidogrel and coronary artery bypass graft. Citations from available articles were used for additional references and ClinicalTrials.gov was accessed for abstracts of ongoing studies. STUDY SELECTION AND DATA EXTRACTION: Peer-reviewed studies that evaluated DAPT use after CABG surgery in adult humans were assessed for inclusion. DATA SYNTHESIS: Four randomized clinical trials evaluating surrogate end points and 9 studies (3 subgroup analyses, 6 observational) evaluating clinical outcomes were reviewed. Three clinical trials assessing surrogate end points failed to demonstrate an improvement in graft patency with DAPT use, while 1 clinical trial found an increase in graft patency. As for clinical outcomes, 1 subgroup analysis demonstrated that the benefit of DAPT post-CABG after a non-ST-elevation acute coronary syndrome diminished following surgery, while an observational study demonstrated a trend toward decreased mortality. In post-CABG patients who did not experience acute coronary syndrome, 2 subgroup analyses proved inconclusive and an observational study found DAPT use to be associated with reducing in-hospital mortality, while another observational study was not associated with reduced long-term mortality. Three observational studies in off-pump CABG patients showed that DAPT use was feasible. CONCLUSIONS: Evidence for DAPT use following CABG is limited to subgroup analyses, observational studies, and trials with surrogate end points. The majority of clinical trials have failed to demonstrate an improvement in graft patency with DAPT. Current evidence does not support the use of DAPT to improve graft patency, and more evidence from randomized controlled trials assessing clinical outcomes is necessary to make definitive recommendations.