Safety issues of adjunctive clopidogrel in patients discharged after percutaneous coronary intervention with stent placement and requiring oral anticoagulation

Indications for percutaneous coronary intervention with stent placement are increasing; some candidates already require oral anticoagulation. Safety of triple antithrombotic therapy — aspirin (ASA), clopidogrel and oral anticoagulation (OAC) — remains largely unknown. In order to study hemorrhagic complications in those patients, we identified thirty-three patients from our anticoagulation clinic registry who were prescribed triple antithrombotic therapy. All hemorrhagic events were collected and classified as non-severe (NSH) or severe (SH). The same population provided a control to determine increased risk from addition of a second antiplatelet drug. Overall, patients were followed for 53 patient-months while on triple therapy (TT) and 869 patient-months on double therapy. Patients in TT group had more hemorrhages (90.6% patient-years vs 8.29% patient-years, p < 0.01) due to an increase in NSH (90.6% patient-years vs 5.52% patient-years, p < 0.01), without changes in SH. Mean international normalized ratio (INR) was similar in both groups and INR at bleeding time was not uniformly increased. We conclude that in patients with an AAS and OAC based regimen, addition of clopidogrel because of a stent placement results in a significant increase in NSH but no increase in SH.