Enhanced platelet inhibition by clopidogrel and risk of bleeding in patients requiring oral anticoagulation after drug-eluting stent implantation

Aims: Clopidogrel is the P2Y₁₂ inhibitor of choice in patients who undergo PCI and have an indication for oral anticoagulation (OAC). Prediction of the bleeding risk is of major interest in this population. The aim of this analysis was to investigate whether an enhanced platelet inhibition by clopidogrel measured by platelet function testing (PFT) with the Multiplate Analyzer is associated with an increased bleeding risk in patients on triple antithrombotic therapy.

Methods and results: This investigation was performed in a cohort of 524 patients from the randomised ISAR-TRIPLE trial; 458 (87.4%) had PFT results available in the first 24 hours after PCI. Patients belonging to the lowest quintile according to PFT were considered as enhanced responders to clopidogrel. The primary endpoint was major bleeding according to TIMI criteria at nine months. The median of ADP-induced platelet aggregation in the whole population was 163 AU*min (107-241). Patients in the lowest quintile had values below 93 AU*min. These enhanced responders (92 patients) had a significantly higher risk of TIMI major bleeding (hazard ratio [HR] 3.13, 95% confidence interval [CI]: 1.38-7.09, p=0.01) and overall mortality (HR 3.42, 95% CI: 1.55-7.52, p=0.004) compared with the remaining patients (366 patients). No significant difference was observed for the secondary combined ischaemic endpoint (HR 1.27, 95% CI: 0.47-3.47, p=0.64).

Conclusions: Enhanced platelet inhibition delivered by clopidogrel is associated with an increased risk for major bleeding and death in patients on OAC who undergo PCI. These results support the use of PFT to identify patients with an increased risk for bleeding.