Beta blockers have many uses in medicine, chief among these is in the treatment of patients with coronary artery disease (CAD) and angina.
Beta blockers work by blocking the effect of adrenaline on the heart, which results in keeping the heart rate relatively slow during periods of exercise or stress, and in reducing the force of heart muscle contraction. Both of these effects reduce the amount of oxygen required by the heart muscle. Reducing the amount of oxygen used by the heart allows the heart to function longer without developing ischemia, even when blood flow through the coronary arteries is partially blocked by atherosclerosis.
In patients with angina, beta blockers are effective in improving the amount of exercise that can be performed without developing ischemia or angina. In addition, beta blockers are the only anti-angina drugs that have been shown to lower the risk of having another myocardial infarction in patients who have already had a heart attack. And finally, in patients who have had a myocardial infarction or who have heart failure, beta blockers have been shown to significantly improve overall survival. The benefits provided by beta blockers have made them the drugs of first choice in treating patients with CAD and angina.
The main side effects of beta blockers include bradycardia (slow heart rate), breathing difficulties in people who have asthma or chronic lung disease, fatigue, worsening of symptoms of peripheral artery disease, depression, and erectile dysfunction. Beta blockers should also be avoided in patients with angina due to Prinzmetal's angina (coronary artery spasm), since in these patients beta blockers can occasionally cause more spasm.
Many of these side effects can be avoided in patients with angina by using beta blockers that work primarily on the heart itself, and that have relatively little effect on the blood vessels, lungs, and central nervous system. These "cardioselective" beta blockers are Tenormin (atenolol) and metoprolol (Lopressor, Toprol XL).
Read here for more on the noninvasive treatment of angina.
Sources:
Fox, K, Garcia, MA, Ardissino, D, et al. Guidelines on the management of stable angina pectoris: executive summary: the Task Force on the Management of Stable Angina Pectoris of the European Society of Cardiology. Eur Heart J 2006; 27:1341.
Frishman, WH, Lazar, EJ, Gorodokin, G. Pharmacokinetic optimization of therapy with beta-adrenergic blocking agents. Clin Pharmacokinet 1991; 20:311.
