20-30% of patients taking oral anticoagulants also have ischaemic heart disease that requires treatment by percutaneous coronary intervention (PCI), thereby necessitating dual anti-platelet therapy to prevent stent thrombosis. However, the combination of dual anti-platelet therapy (DAP) and anti-coagulants is associated with a high annual risk of fatal and non-fatal bleeding episodes. This study hypothesised that in patients who must continue with oral anti-coagulants, clopidogrel alone would reduce the risk of bleeding – while not increasing the risk of thrombotic events – compared to clopidogrel and aspirin.

The What is the Optimal antiplatElet and anticoagulant therapy in patients with oral anticoagulation and coronary StenTing (WOEST) study was an open-label, randomised, controlled trial carried out at 15 sites in the Netherlands and Belgium between 2008 and 2011. Patients taking oral anti-coagulants and undergoing PCI were assigned to clopidogrel alone, or clopidogrel plus aspirin. The primary outcome measure was any bleeding episode within one year of PCI; analysis was by intention to treat.

Of the 573 patients enrolled in the study, one-year data were available for 279 (98.2%) of patients assigned double therapy (clopidogrel and oral anticoagulant) and for 284 (98.3%) of patients assigned triple therapy (aspirin, clopidogrel, and oral anticoagulant). In patients receiving double therapy, bleeding episodes were noted in only 54 (19.4%) of patients, compared to 126 (44.4%) in patients receiving triple therapy (hazard ration 0.36, p<0.0001). Multiple bleeding episodes were also more common in the triple therapy group (2.2% vs 12.0%), as were blood transfusions (3.9% vs. 9.5%).

Conclusions:

In patients taking oral anticoagulants who underwent PCI, the use of clopidogrel without aspirin was associated with a significant reduction in bleeding complications and no increase in the rate of thrombotic events.

• DeWilde WJM, Oirbans T, Verheugt FWA et al. Use of clopidogrel with or without aspirin in patients taking oral anticoagulant therapy and undergoing percutaneous coronary intervention: an open-label, randomised, controlled trial. Lancet 2013;381:1107-1115.