Examples

How It Works

Antiarrhythmic medicines help return the heart to its normal sinus rhythm, maintain the rhythm after it has been achieved, and/or reduce the heart rate while you are in atrial fibrillation. These medicines stabilize the heart muscle tissue. Antiarrhythmics such as amiodarone or sotalol also slow the heart rate by blocking impulses that pass through the AV node in the heart.

Why It Is Used

Antiarrhythmic medicines are used to convert atrial fibrillation to a normal rhythm. These medicines may be used before electrical cardioversion and may help maintain a normal heart rhythm after successful cardioversion. Ibutilide, another antiarrhythmic, may improve chances of successful cardioversion when used before cardioversion.

How Well It Works

Antiarrhythmic medicines can maintain a normal rhythm in 35% to 75% of the people who use them.¹

Side Effects

Antiarrhythmic medicines may increase the risk of developing a more severe irregular heart rate problem (ventricular tachycardia or ventricular fibrillation). Close monitoring while taking the medicine is important. The risk of side effects is greater with more severe underlying heart disease.

Side effects of antiarrhythmics include:

• Slow heartbeat.
• Palpitations.
• Fatigue.
• Headache.
• Dizziness.
• Nausea or vomiting.
• Unusual taste in the mouth.
• Stomach pain.
• Constipation or diarrhea.
• Difficulty breathing.
• Rash.
• Vision problems.
• Urinary retention in men.
• Arrhythmia.

Other, less common side effects include:

• Sensitivity to light (photosensitivity).
• Thyroid disorders.
• Cirrhosis of the liver.
• Peripheral neuropathies.

Rare side effects of amiodarone include:

• Scarring of the lungs (pulmonary toxicity).
• A blue tinge to the skin.
• Vision problems.
• Numbness.
• Tremor.

The U.S. Food and Drug Administration (FDA) has issued warnings about amiodarone (Cordarone). People taking this medicine should be aware that it may cause serious side effects that can lead to death, including lung damage, liver damage, and more severe heartbeat problems. Amiodarone is typically used for people who have severe symptoms when other medicines have failed.

If you take amiodarone and simvastatin, which is a cholesterol medicine, you may have a higher risk of a serious muscle problem called rhabdomyolysis. Simvastatin medicines include Zocor and Vytorin.

Talk to your doctor if you have any side effects or any concerns about taking amiodarone. People may be able to take amiodarone safely when they are checked carefully by their doctors.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Antiarrhythmics must be used carefully to treat atrial fibrillation because they can cause severe irregular heart rate problems and other serious side effects. They often are used for people who have severe symptoms of atrial fibrillation or whose symptoms are bothersome. Antiarrhythmics also are used after cardioversion to control heart rhythm.

For some people, antiarrhythmic medicines may not be the preferred treatment. In a study called the AFFIRM trial, medicines to slow the heart rate, such as beta-blockers, calcium channel blockers, and digoxin, were found to be preferable to antiarrhythmic medicines as a first-line treatment for certain people with atrial fibrillation, specifically older people at risk for stroke who did not have severe symptoms of atrial fibrillation.²

Taking medicines that only slow your heart rate will leave you in atrial fibrillation. But most people tolerate an irregular heart rhythm if the rate is kept between 60 and 100 beats per minute. Also, the AFFIRM study found that antiarrhythmic medicines were expensive, often had side effects, and frequently did not prevent atrial fibrillation from recurring.² So, treatment with a rate-control medicine and an anticoagulant might be a good option for people who do not have atrial fibrillation symptoms when their heart rate is controlled.

Amiodarone is an effective antiarrhythmic for treating atrial fibrillation, but its use is limited by its potential severe side effects.

Sotalol has both antiarrhythmic and beta-blocking properties.

Because atrial fibrillation often returns, you may also need to take anticoagulant medicine (warfarin, such as Coumadin).

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