Background Advances in coronary angioplasty and adjunct pharmacology have improved patient outcomes after primary percutaneous coronary intervention (PCI) in acute myocardial infarction (AMI). However, several areas for improvement remain. Hemorrhagic complications, which are common in patients receiving intense anticoagulant and antiplatelet agents during primary PCI to suppress ischemia, have been strongly associated with early and late mortality. Moreover, restenosis after bare-metal stents (BMSs) frequently results in symptom recurrence and the need for repeat rehospitalization and revascularization procedures. Newer pharmacologic agents and drug-eluting stents may address both of these issues.Study Design In the HORIZONS-AMI trial, 3,602 patients with AMI undergoing primary PCI were prospectively randomized to unfractionated heparin plus routine use of glycoprotein (GP) IIb/IIIa inhibitors versus the direct thrombin inhibitor bivalirudin plus provisional use of GP IIb/IIIa inhibitors reserved for predefined thrombotic complications. In a second randomization, 3,011 eligible patients were randomly assigned to either a polymer-based paclitaxel-eluting stent or to an otherwise identical BMS. The study was powered for the assessment of sequential safety and efficacy end points for each specific randomization, with clinical end points assessed at 30 days, 1 year, and then annually for 5 years.Summary The ongoing HORIZONS-AMI trial will determine whether bivalirudin monotherapy reduces bleeding complications and improves overall event-free survival compared with unfractionated heparin plus the routine use of GP IIb/IIIa inhibitors in patients undergoing primary PCI for AMI. Furthermore, this study will determine whether paclitaxel-eluting stents safely reduce rates of ischemic target lesion revascularization compared with BMSs in the setting of primary PCI.

The impact of time to treatment on outcomes after primary percutaneous coronary intervention (PCI) is controversial, and there are few data about time to treatment and infarct size. The EMERALD trial randomly assigned 501 high-risk patients with ST-elevation myocardial infarction undergoing primary PCI to stenting with or without GuardWire (Medtronic, Santa Rosa, California) distal protection. Infarct size using sestamibi imaging at 5 to 14 days and clinical outcomes were examined by time to treatment. There were no differences in outcomes between distal protection and control patients. Shorter time to reperfusion (<2 vs 2 to 3 vs >3 to 4 vs >4 hours) was associated with smaller infarct size (2% vs 9% vs 12% vs 11%, p=0.026), trends for better myocardial blush (p=0.08), and lower 6-month mortality rates (0% vs 0% vs 2.4% vs 5.3%, p=0.06). Incremental delays in reperfusion after 2 hours had little impact on infarct size. Shorter time to reperfusion impacted on infarct size in patients with anterior infarction (0% vs 17% vs 20.5% vs 30.5%, p=0.026), but not nonanterior infarction (3% vs 7% vs 7.5% vs 10%, p=0.23, p=0.022 for interaction). In conclusion, very early reperfusion with primary PCI is associated with smaller infarct size and has a much greater impact in anterior versus nonanterior infarction. Incremental delays in reperfusion after 2 hours have less effect on infarct size. These data have implications regarding the triage of patients for primary PCI.