Objective To determine the individual variability in the response to aspirin and/or clopidogrel and its impact on graft patency after off-pump coronary artery bypass grafting.
Design A single-centre prospective randomised controlled study designed according to the Consolidated Standards of Reporting Trials statement. Randomisation was obtained by a computer-generated algorithm.
Setting University medical school in Italy.
Patients 300 patients who underwent off-pump coronary artery bypass grafting were randomised to receive aspirin (n=150) or aspirin plus clopidogrel (n=150).
Intervention Aspirin 100 mg or aspirin 100 mg plus clopidogrel 75 mg daily was initiated when postoperative chest tube drainage was ≤50 ml/h for 2 h and patients were followed up for 12 months.
Main outcome measures Qualitative and quantitative assessment of platelet function, angiographic evaluation of coronary revascularisation by 64-slice CT and clinical outcome.
Results In the aspirin group, 49 patients (32.6%) were aspirin resistant and, in the aspirin-clopidogrel group, 19 patients (12.6%) were aspirin and clopidogrel resistant. The platelet response to aspirin was similar in all aspirin responders despite the study arm (Aspirin Reaction Units 313.2±44.8 vs 323.6±53.6; p=0.07). The platelet response to clopidogrel was enhanced by aspirin in patients responsive to both aspirin and clopidogrel (synergistic effect) compared with responders to clopidogrel only (P2Y12 Reaction Units 139.9±15.5 vs 179.4±18.5; p<0.001). Combined therapy was associated with a reduced vein graft occlusion rate (7.4% vs 13.1%; p=0.04). Antiplatelet resistance was a predictor of graft occlusion (RR 3.6, 95% CI 2.5 to 6.9; p<0.001). Synergistic aspirin and clopidogrel activity was a strong predictor of vein graft patency (RR 5.1, 95% CI 1.4 to 16.3; p<0.01).
Conclusions Combined clopidogrel and aspirin overcome single drug resistances, are safe for bleeding and improve venous graft patency.
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Competing interests None.
Ethics approval The study was approved by the ethics committee of the Federico II University Medical School of Naples and the hospital's Institutional Review Board. The presented data are anonymised and there is no risk of identification.
Patient consent Written consent was obtained from each patient.
Provenance and peer review Not commissioned; externally peer reviewed.
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