The effects of beta-blockers on acute myocardial infarction can be divided into those that are immediate and long-term (secondary prevention). beta-blockers given early in the course of infarction may diminish myocardial oxygen demand and therefore reduce chest pain and infarct size. Many clinical trials have clearly shown that both early and long-term treatment with beta-blockers reduce cardiac mortality and the rate of re-infarction. As seen in recommendations of ACC (American College of Cardiology)/AHA (American Heart Association) guidelines for management of acute myocardial infarction, all patients without a contraindication to beta-blockers should be treated with beta-blockers from very early course of the onset and be continued indefinitely.