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.

Duration of Triple Therapy in Patients Requiring Oral Anticoagulation After Drug-Eluting Stent Implantation: The ISAR-TRIPLE Trial.

BACKGROUND: Patients receiving oral anticoagulation (OAC) who undergo drug-eluting stent (DES) implantation require additional dual antiplatelet therapy with aspirin and clopidogrel. Such triple therapy confers an elevated bleeding risk, and its optimal duration is not known. OBJECTIVES: The goal of this study was to evaluate whether shortening the duration of clopidogrel therapy from 6 months to 6 weeks after DES implantation was associated with a superior net clinical outcome in patients receiving concomitant aspirin and OAC. METHODS: In this randomized, open-label trial, we enrolled patients receiving OAC who underwent DES implantation at 3 European centers between September 2008 and December 2013. A total of 614 patients receiving concomitant aspirin and OAC were randomized to either 6-week clopidogrel therapy (n=307) or 6-month clopidogrel therapy (n=307). The primary endpoint was a composite of death, myocardial infarction (MI), definite stent thrombosis, stroke, or Thrombolysis In Myocardial Infarction (TIMI) major bleeding at 9 months. RESULTS: The primary endpoint occurred in 30 patients (9.8%) in the 6-week group compared with 27 patients (8.8%) in the 6-month group (hazard ratio [HR]: 1.14; 95% CI: 0.68 to 1.91; p=0.63). There were no significant differences for the secondary combined ischemic endpoint of cardiac death, MI, definite stent thrombosis, and ischemic stroke (12 [4.0%] vs. 13 [4.3%]; HR: 0.93; 95% CI: 0.43 to 2.05; p=0.87) or the secondary bleeding endpoint of TIMI major bleeding (16 [5.3%] vs. 12 [4.0%]; HR: 1.35; 95% CI: 0.64 to 2.84; p=0.44). CONCLUSIONS: Six weeks of triple therapy was not superior to 6 months with respect to net clinical outcomes. These results suggest that physicians should weigh the trade-off between ischemic and bleeding risk when choosing the shorter or longer duration of triple therapy. (Triple Therapy in Patients on Oral Anticoagulation After Drug Eluting Stent Implantation [ISAR-TRIPLE]; NCT00776633).