Secondary prevention after myocardial infarction: in favor of beta-blockers.

A large number of pharmacological trials have been carried out, attempting to reduce the mortality (10-15%) in the year following of an acute myocardial infarction (MI) and/or the recurrence of ischemic events. Thrombolytic therapy and beta-blockade are the only interventions to be associated with a significant decrease in cardiac mortality. Early intervention with intravenous beta-blockers aims at limiting infarct size and at decreasing mortality. The Swedish study using intravenous (15 mg) followed by oral (200 mg/day) metoprolol showed a 36% reduction in mortality after the first week, a benefit persisting after 1 year. The combination of streptokinase and intravenous atenolol is safe and may be beneficial in selected patients. Large-scale controlled multicenter studies have shown that beta-blockers introduced within the first 3 days after acute MI significantly reduce total mortality and/or sudden death in the year following the acute event. Some of these studies demonstrate a reduction in recurrence of MI. The reduction (averaging 25%) in mortality may be explained by the anti-ischemic action of beta-blockers and the prevention of arrhythmia-induced death. Introduced early, beta-blockers may reduce the size of the initial MI as well as subsequent infarction and/or ischemia. Furthermore the antistress action of beta-blockers results in a decrease in free fatty acids, with their untoward effect in acute MI. Antiplatelet aggregation may also play a role. These properties of beta-blocking agents should be utilized in every patient with acute MI in the absence of any major contraindication. Elective indications include patients with hypertension, angina pectoris, and/or ventricular arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)