What are antiarrhythmic drugs?

Antiarrhythmics are medications that prevent and treat a heart rhythm that is too fast or irregular also known as arrhythmias. Arrhythmia involves a problem with your heart’s electrical system. Your heart may beat too quickly, too slowly or erratically (irregularly). Antiarrhythmics treat abnormal heart rhythms including atrial fibrillation, atrial flutter, ventricular tachycardia or ventricular fibrillation.

How do antiarrhythmics work?

In general, antiarrhythmics reset your heart to a normal rhythm or prevent episodes of arrhythmia. They act on the heart’s various electrical channels (see below) to:

  • Stop an irregular, extra electrical impulse in your heart.
  • Prevent abnormally fast electrical impulses from traveling along heart tissues.

There are several classes of antiarrhythmics. Each class works in a different way, depending on the type of arrhythmia and its cause.

Most arrhythmia medications are taken by mouth over a long period of time for lasting treatment. Some are delivered intravenously (injected into the bloodstream) for patients who are unstable or cannot take oral medications.

What are the treatment options for abnormal heart rhythms?

There are several types of arrhythmia treatments, including:

  • Medications.
  • Lifestyle changes.
  • Implanted medical devices.
  • Surgery.

A healthcare provider recommends treatment depending on the type of arrhythmia you have and how serious it is. They may recommend antiarrhythmic medications if arrhythmia:

  • Doesn’t respond to lifestyle changes.
  • Interferes with your daily activities.
  • Might cause a life-threatening complication, such as heart failure, cardiac arrest or stroke.

What are the classes of antiarrhythmic medications?

There are four classes of antiarrhythmics, based on the Vaughan-Williams (VW) classification system:

  • Class I, sodium channel blockers: These drugs prevent sodium from getting through cell membranes. This can slow electrical impulses in the heart muscle. Examples include disopyramide, flecainide, mexiletine, propafenone and quinidine.
  • Class II, beta blockers: These drugs slow down the heart rate, often by blocking hormones such as adrenaline. Examples include acebutolol, atenolol, bisoprolol, metoprolol, nadolol and propranolol.
  • Class III, potassium channel blockers: These drugs prevent potassium from getting through cell membranes. This can slow down electrical impulses in all of the heart’s cells. Examples include amiodarone, bretylium, dofetilide, dronedarone, ibutilide and sotalol.
  • Class IV, nondihydropyridine calcium channel blockers: These drugs block calcium channels in heart muscle. This can decrease heart rate and contractions. Examples include diltiazem and verapamil.

Other antiarrhythmic drugs not included in the VW classification system include:

  • Adenosine: This medication can block or slow down electrical impulses at the atrioventricular node, between the upper and lower chambers of the heart.
  • Digoxin: This drug can slow the heart rate and increase contractility of the heart.

Arrhythmia treatment also may involve other medications that are not antiarrhythmics, such as anticoagulants (blood thinners).

How effective are antiarrhythmic drugs?

Antiarrhythmics are often very effective. But it may take several tries to find the medication and dose that works best for you depending on efficacy and tolerability.

What are the benefits of using antiarrhythmic agents?

If you have an arrhythmia, antiarrhythmics can make you feel better and prevent serious complications. They can relieve the common symptoms of arrhythmia, such as:

What are the risks of using antiarrhythmics?

Arrhythmia medications can lead to other arrhythmias. If you’re taking an antiarrhythmic, you must be monitored carefully by healthcare providers. They can adjust your dose or recommend a different medicine if you have new or worsening arrhythmia symptoms.

Several healthcare professionals may be involved in monitoring your health, including:

  • Cardiologist, a heart physician.
  • Electrophysiologist, a heart physician who specializes in the heart’s electrical system including arrhythmia.
  • Primary care provider or nurse.
  • Pharmacist.

Can you overdose on antiarrhythmics?

If you’re taking antiarrhythmics, it’s essential to follow all instructions from your healthcare providers. A person can overdose on arrhythmia medications, leading to:

  • Confusion.
  • Damage to heart tissue.
  • Respiratory arrest.
  • Sedation (inability to wake up, or limited awareness of surroundings).
  • Seizures.
  • Coma.

What side effects do antiarrhythmics have?

Antiarrhythmics can cause several side effects, including:

  • Constipation.
  • Dizziness.
  • Excessive thirst.
  • Skin changes (for example, red or dry skin).
  • Headache.
  • Nausea.
  • Ringing in the ears (tinnitus).
  • Sensitivity to the sun.
  • Swelling from fluid buildup (edema).
  • Trouble peeing.
  • Vision changes.
  • Worsening of asthma.

What interactions should I watch out for?

Antiarrhythmics can interact with other drugs. Make sure your healthcare providers know about all medications you take, including:

  • Creams or ointments.
  • Inhalers.
  • Other prescription drugs.
  • Over-the-counter medications.
  • Vitamins, minerals, herbs, supplements or other natural health products.

If you have questions about arrhythmia drug interactions, talk to your cardiologist or pharmacist. Please also discuss if you are pregnant or are planning to become pregnant before starting these medications.

How long should I take antiarrhythmics?

Most antiarrhythmics are long-term medications. You take it until the drug is no longer effective or you can’t tolerate the side effects. Never stop taking an arrhythmia medication or change the dose without talking to your healthcare provider.

A note from Cleveland Clinic

Antiarrhythmics are medications that prevent and treat an abnormal heart rate and rhythm. The drugs can reduce the symptoms of arrhythmia and prevent serious complications. If you’re taking arrhythmia medications, you must follow your healthcare providers’ instructions and be monitored for side effects and complications.

Last reviewed by a Cleveland Clinic medical professional on 04/28/2022.

References

  • American Heart Association. Medications for Arrhythmia. (https://www.heart.org/en/health-topics/arrhythmia/prevention--treatment-of-arrhythmia/medications-for-arrhythmia) Accessed 9/26/2021.
  • Heart and Stroke Foundation of Canada. Antiarrhythmics. (https://www.heartandstroke.ca/heart-disease/treatments/medications/antiarrythmics) Accessed 9/26/2021.
  • King GS, Goyal A, Grigorova Y, Hashmi MF. Antiarrhythmic Medications. (https://www.ncbi.nlm.nih.gov/books/NBK482322/) [Updated 14 Aug 2021]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Accessed 9/26/2021.
  • Merck Manual (Professional Version). Drugs for Arrhythmias. (https://www.merckmanuals.com/professional/cardiovascular-disorders/arrhythmias-and-conduction-disorders/drugs-for-arrhythmias) Accessed 9/26/2021.

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