Drug Therapy: Antiarrhythmics

Antiarrhythmics are used to treat disorders of the heart's rhythm, such as arrhythmias or atrial fibrillation. These disorders cause heart palpitations, irregular heartbeats, fast heartbeats, lightheadedness, fainting, chest pain and shortness of breath.

Different types of antiarrhythmics work in different ways. Generally, they slow the electrical impulses in the heart so that the heart can return to a regular rhythm. The four types of antiarrhythmic drugs are:

  • Sodium-channel blockers, which slow the conduction of electrical impulses in the heart
  • Beta blockers, which block the impulses that may cause an irregular heart beat by interfering with hormonal influences (such as adrenaline) on the heart's cells. These actions reduce the blood pressure and heart rate.
  • Potassium-channel blockers, which slow the electrical impulses in the heart
  • Calcium-channel blockers, which work much the same as beta blockers do
Because each type of antiarrhythmic drug has a slightly different effect, patients may need to work closely with the doctor and try more than one before finding what works best. Sometimes these types of drugs can cause more arrhytmias or make them worse, so the patient would need to be monitored over the course of a 24-hour period using a Holter monitor or by doing electrophysiology studies.

If these medications are prescribed, the doctor should be made aware of any other drug, vitamin, mineral or herbal supplement the patient is taking, especially blood-thinning drugs, such as warfarin, digoxin or insulin (either by injection or orally), because some antiarrhythmic drugs can interact with them. Some antiarrhythmic drugs can also cause sensitivity to sunlight, making patients more prone to sunburn.