Trials of precatheterization laboratory (eg, ambulance or emergency room) administered GP IIb/IIIa inhibitors in patients with STEMI undergoing PCI, with or without fibrinolytic therapy, have generally shown no clinical benefit, and GP IIb/IIIa inhibitor use in this setting may be associated with an increased risk of bleeding.605 610,612 Stud- ies of intracoronary GP IIb/IIIa inhibitor administration (predominantly using abciximab) consist of several small RCTs, retrospective analyses, retrospective and prospec- tive registries, cohort analyses, and case reports. Although most of these published studies have reported some benefit of intracoronary administration in terms of acute angio- graphic parameters, infarct size, left ventricle myocardial salvage, and composite clinical endpoints, several other studies have not detected any benefit with intracoronary Trials of GP IIb/IIIa inhibitors in patients with UA/ NSTEMI undergoing PCI demonstrated reduced ischemic outcomes, particularly in those with high-risk features such as positive biomarkers. Most trials were conducted in a prior PCI era and without P2Y12 inhibitor pretreat- ment,613,615,618,632,633 although several trials have also demon- strated benefit in patients with high-risk features pretreated with clopidogrel.616,619 In most older studies of stable patients undergoing balloon angioplasty or coronary stenting, treat- ment with GP IIb/IIIa inhibitors resulted in a reduction of composite ischemic events, primarily enzymatically defined MI.613 618,620,621,634,635 More contemporary trials of patients pretreated with a thienopyridine have not demonstrated any benefit with GP IIb/IIIa inhibitor therapy in patients with stable symptoms undergoing elective PCI.619,622 624 5.7.4. Anticoagulant Therapy 5.7.4.1. Use of Parenteral Anticoagulants During PCI: Recommendation Class I 1. An anticoagulant should be administered to patients undergoing PCI. (Level of Evidence: C) Anticoagulant therapy prevents thrombus formation at the site of arterial injury, on the coronary guidewire, and in the catheters used for PCI.8 With rare exceptions,636 all PCI studies have used some form of anticoagulant. 