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.