What anti-thrombotic therapy is best with primary PCI for acute ST elevation myocardial infarction: how should the HORIZONS trial change current practice?

The current standard of care for anti-thrombotic therapy with primary PCI for acute ST elevation myocardial infarction (STEMI) is aspirin, clopidogrel, unfractionated heparin and platelet glycoprotein IIb/IIIa inhibitors. However, heparin and glycoprotein IIb/IIIa inhibitors are associated with a high incidence of bleeding, and many of the trials documenting benefit with this therapy were performed before the widespread use of stents and clopidogrel. Bivalirudin is a direct thrombin inhibitor which has been found to have similar efficacy with less bleeding compared with heparin plus glycoprotein IIb/IIIa inhibitors when used with elective PCI and with PCI for unstable angina and non-ST elevation myocardial infarction. The HORIZONS trial evaluated bivalirudin compared with unfractionated heparin and IIb/IIIa inhibitors in patients with STEMI treated with primary PCI and found similar MACE (major adverse cardiac events) with less bleeding and a lower incidence of net adverse clinical events (MACE or major bleeding) at 30 days. Mortality at 30 days was also significantly less with bivalirudin. These results make a strong case for the use of bivalirudin with primary PCI in the great majority of patients with STEMI, with the possible exception of patients with cardiogenic shock or stent thrombosis, and patients with a large thrombus burden or no re-flow following PCI. In the latter case, platelet glycoprotein IIb/IIIa inhibitors would be used as a bail-out strategy.