These agents were among the first therapies demonstrated to reduce infarct size. -Blockers reduce early sudden death after MI both via antiarrhythmic effects and by preventing myocardial rupture. In patients with STEMI, the long-term benefits of long-term postdischarge -blocker administration have been shown in multiple trials.191 Therefore, routine discharge use of -blockers is now a qual- ity performance measure for patients with ACS. Although -blockers should be initiated early and contin- ued for at least 3 years after ACS,176 there has been increased attention on the appropriate selection of patients for the use of early intravenous -blockers after ACS. Early intravenous -blockade was shown in a number of trials performed in the fibrinolytic era to reduce either mortality or recurrent MI192,193 and thus was used as routine therapy in ACS for many years. However, the Clopidogrel and Metoprolol in Myocardial Infarction Trial (COMMIT)/Chinese Cardiac Study (CCC) 2 trial has led to a revision of the recommendations for intra- venous -blocker use in ACS.194 This study randomized 45852 AMI patients at presentation to intravenous and then oral -blockers versus placebo and assessed the coprimary outcomes of the composite of death, reinfarction, or cardiac arrest and death resulting from any cause. At discharge or up to 4 weeks, neither outcome was reduced with metoprolol. However, the COMMIT trial demonstrated a reduction in rein- farction (2.0% versus 2.5%) and ventricular fibrillation (2.5% versus 3.0%), but at the expense of an increase in cardiogenic shock (5.0% versus 3.9%) with intravenous -blocker use. The excess risk of shock was highest in the first 2 days of hospitalization, especially in patients with evidence of hemo- dynamic instability or borderline hemodynamics at presenta- tion. 