Beta-adrenergic blockade in cardiac infarction

Abstract

Beta-adrenergic blocking drugs may be considered in the treatment of patients with acute myocardial infarction for one or more of the following reasons: 1. 1. To reduce cardiac work and myocardial oxygen consumption. 2. 2. To treat or attempt prevention ofectopic beats and dangerous arrhythmias. 3. 3. To relieve persisting post infarction pain. Although the drugs may be rationally used in individually selected patients, the routine administration of beta-blocking drugs to all patients with cardiac infarction does not prevent arrhythmias, does not prevent recurrent pain, and has no influence upon mortality. Intravenous, and to a lesser extent oral, administration of these drugs may precipitate cardiac failure and pulmonary edema, may lead to hypotension and bradycardia with the development of the shock syndrome and may occasionally result in sudden death. Patients must therefore be carefully selected and the concomitant administration of inotropic agents such as digitalis, oral diuretics and possibly atropine considered. The use of the dextro-isomers which have been shown to have anti-arrhythmic activity but to be devoid of beta-blocking activity may be clinically useful in the future. Newer beta-blocking drugs with less depressant action on the myocardium are being developed and selective blocking drugs acting primarily on cardiac receptors are also becoming available. Drugs with intrinsic inotropic activity may also be useful in that they will block excess catecholamine drive without producing severe myocardial depression. The clinical place for these drugs in acute myocardial infarction is still uncertain.