Background: Patients with high post-loading platelet aggregation (PPA) are at increased risk of stent thrombosis and death after primary percutaneous coronary intervention (pPCI). The objective of the present trial was to examine whether high PPA is associated with adverse clinical outcomes in pPCI patients whose therapy was modified in accordance with PPA.
Methods: We analyzed 961 consecutive pPCI patients who underwent pPCI between February 2008 and June 2011. High PPA was defined as PPA >50%, 24h after the loading dose. Patients with high PPA were treated with aspirin 300 mg, clopidogrel 150 mg or ticlopidine 500 mg for 30 days. The co-primary efficacy and safety end points at 30 days were major adverse cardiovascular events (MACE) and major bleeding.
Results: We detected high PPA to clopidogrel and aspirin in 44.4% and 16.5% of patients, respectively. The rates of 30-day MACE (adjusted OR 1.76, 95% CI 1.05-2.97), definite subacute stent thrombosis (DSST, adjusted OR 2.15, 95% CI 1.09-4.22) and nonfatal infarction (adjusted OR 3.99, 95% CI 1.57-10.13) were higher in patients with high PPA to clopidogrel compared with responders. High PPA to aspirin was not associated with an adverse 30-day clinical outcome. Compared with high PPA patients who were not tailored, a significantly better outcome with respect to the primary end point was observed in the tailored group (OR 0.42, 95% CI 0.19-0.93).
Conclusion: High PPA to clopidogrel was an independent predictor of 30-day adverse events after pPCI. Among high PPA patients, tailoring was associated with an improved primary outcome.
Keywords: Aggregation; Antiplatelet therapy; Primary PCI.
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