How to Manage Antiplatelet Therapy for Stenting in a Patient Requiring Oral Anticoagulants

The optimal antiplatelet regimen for patients on oral anticoagulants undergoing coronary stenting continues to be controversial. It is not an insignificant problem, as 5-7 % of patients undergoing stenting are on oral anticoagulation for atrial fibrillation, a prosthetic valve, a recent left ventricular thrombus and recent pulmonary embolus. When given in combination with dual antiplatelet therapy, major bleeding is significantly increased, which is associated with an increased mortality. The balance between a reduction in stroke, stent thrombosis and myocardial infarction without a significant increase in major bleeding requires choosing therapy based upon the estimation of the risks of each adverse event. In patients with a low risk of stroke, such as those with atrial fibrillation and a CHADS(2) score of 0-1, dual antiplatelet therapy alone is sufficient. In those at moderate to high risk of stroke, dose-adjusted oral anticoagulation is needed. In those with the highest bleeding risk, use of a bare metal stent is strongly advised. In addition to bare metal stent use, the use of proton pump inhibitors, tight control of the international normalized ratio (INR) and only one month of dual antiplatelet therapy can reduce the bleeding risk without an increase in stroke or stent thrombosis. When a drug eluting stent (DES) is needed, a second generation DES should be used and triple therapy continued for 6 months (12 months if stent thrombosis risk is very high), followed by a single antiplatelet therapy and an oral anticoagulant. Since the newer antiplatelet agents and anticoagulants have not been studied in this setting, clopidogrel and warfarin should be used. Recently, the WOEST trial suggested that clopidogrel alone plus an oral anticoagulant resulted in an equal outcome with a significantly lower bleeding risk when compared to triple therapy. If confirmed, this regimen may become the standard of care. Presently, however, limiting the duration of triple therapy followed by clopidogrel and an oral anticoagulant seems the best option for the majority of patients to minimize bleeding risk without an increase in other adverse events.