Clinical Use of Beta Blockers

Summary

Beta blockers are versatile medications used to treat a wide range of conditions.

In cardiovascular health, they are commonly prescribed to treat hypertension, angina, heart attacks, and chronic heart failure. Beta blockers have been shown to reduce mortality in heart attacks and heart failure. They are also used to manage arrhythmias as Class 2 antiarrhythmics and can be effective in treating dilated and hypertrophic cardiomyopathies, as well as aortic dissection.

Beyond cardiovascular uses, beta blockers are employed in the treatment of hyperthyroidism, esophageal varices, anxiety, essential tremor, extrapyramidal symptoms, and glaucoma. They are also effective in preventing migraine headaches.

In certain conditions, an alpha blocker must be given first before using a beta blocker to prevent unopposed alpha receptor stimulation. These conditions include cocaine toxicity, which should be treated with extreme caution, and pheochromocytoma.

Key Points

• Clinical Use of Beta Blockers
  • Treats Angina Pectoris
    • ↓ O2 consumption by heart by decreasing heart rate and contractility
  • Treats Myocardial Infarction (M.I.)
    • ↓ O2 demand can relieve symptoms and improve acute cases
    • ↓  mortality (over long term)
  • Treats Hypertension
    • ↓ cardiac output
    • ↓ renin secretion
      • Due to beta-1 blockade at juxtaglomerular apparatus
  • Treats Chronic Heart Failure
    • Note: not used in acute decompensated HF
      • contraindicated in cardiogenic shock (due to decreased CO)
    • Blockade of neurohormonal stress
      • Prevents undesirable cardiac remodeling
    • ↓ mortality (over long term)
  • Treats SVT
    • Class 2 Antiarrhythmic
    • ↓ AV Conduction Velocity
  • Treats Hyperthyroidism/Thyroid Storm
    • Symptom control by lowering heart rate and reducing tremors
  • Treats Hypertrophic Cardiomyopathy
    • Decrease in heart rate increases filling time, which can relieve obstruction
  • Treats Glaucoma
    • ↓ aqueous humor synthesis
    • Eye drop forms (timolol, betaxolol, carteolol) are often used
  • Prevents Variceal Bleeding
    • Reduces hepatic venous pressure gradient and portal hypertension, which lowers pressure on esophageal variceal veins
  • Treats Pheochromocytoma
    • Used after Alpha-Blockade; should never be the initial therapy
    • May be used to treat hypertensive crises
    • Metoprolol and propranolol are used following phenoxybenzamine
  • Use Caution with Treating Cocaine Toxicity
    • Controversial; must be combined with alpha-blockers
    • Evidence suggests beta-blockers should not be used before cocaine is eliminated from body
    • In rare cases, carvedilol or labetalol (mixed alpha-beta blockers) may be used
  • Treats Performance-Type Social Anxiety Disorder (e.g. public speaking)
    • There is no evidence from clinical trials that beta-blockers are effective, although propranolol may be occasionally administered for this purpose
  • Treats Extrapyramidal Symptoms (akathisia)
    • Propranolol reduces involuntary movements, but does not reduce anxiety
  • Treats Migraine (Prophylaxis)
    • Metoprolol, propranolol, and timolol have been shown to be effective for migraine prevention, while atenolol and nadolol are probably effective
  • Treats Essential Tremor
    • Propranolol is the current first-line agent for treatment
  • Treats Aortic Dissection
    • IV beta blockers may be used to manage hypertension in these patients in the hospital setting
  • Treats Dilated Cardiomyopathy
    • Similar mechanism to treatment of heart failure; reduction of myocardial oxygen demand and prevention of heart remodeling is thought to improve long-term mortality