The use of beta-blockers after myocardial infarction.

Several beta-blockers have now been shown to be effective in reducing total mortality during the extended recovery period after myocardial infarction. The rate of occurrence of reinfarction and sudden death is also reduced. While the exact mechanisms of this beneficial effect are unknown, it appears to result from a "class" effect, ie, secondary to beta-blockade, since neither cardioselectivity, intrinsic sympathomimetic activity, nor membrane-stabilizing activity appears to be requisite. The reduction in mortality is seen in all age groups, for all types of infarction, and in all risk groups. On the basis of presently available evidence, in patients without contraindication to beta-blockade, prophylactic treatment with beta-blockers should be initiated between one and four weeks after myocardial infarction. The dosage should be sufficient to blunt the heart rate response to exercise, and therapy should be continued for at least two years. The positive results of several well-designed and conducted studies have proved that the concept of secondary prevention is a valid one and should help to save thousands of lives in the coming decade. It is expected that ongoing investigations will determine the efficacy and safety of earlier institution of beta-blockade, including IV administration in the peri-infarction period. The effectiveness of secondary prevention with other agents, including calcium channel blockers, antiplatelet agents, anticoagulants, lipid-lowering drugs, antiarrhythmics, prostacyclin analogues, and thromboxane synthetase inhibitors, should be investigated further. Additional information is needed on the mechanisms by which beta-blockers reduce mortality, sudden death, and reinfarction, on whether specific beta-blockers and/or specific types of beta-blockers have the greatest benefit, and, as a result of further analysis from some of the studies already published, the effect of beta-blockade after myocardial infarction on angina, rhythm disturbances, lipid profile abnormalities, and the quality of life.