Anticoagulant Therapy to Support Primary PCI: Recommendations Class I 1. For patients with STEMI undergoing primary PCI, the following supportive anticoagulant regimens are recommended: a. UFH, with additional boluses administered as needed to maintain therapeutic activated clotting time levels, taking into account whether a GP IIb/ IIIa receptor antagonist has been administered (Level of Evidence: C); or b. Bivalirudin with or without prior treatment with (Level of Evidence: B) Class IIa 1. In patients with STEMI undergoing PCI who are at high risk of bleeding, it is reasonable to use bivaliru- din monotherapy in preference to the combination of UFH and a GP IIb/IIIa receptor antagonist.248 (Level of Evidence: B) Class III: Harm 1. Fondaparinux should not be used as the sole antico- agulant to support primary PCI because of the risk of catheter thrombosis.304 (Level of Evidence: B) Intravenous UFH titrated to an appropriate activated clot- ting time is a familiar and well-tested strategy for anticoagu- lant therapy at the time of PCI for STEMI. Enoxaparin and fondaparinux have been studied less extensively in this set- ting. 