There are many causes of abnormal heart rhythms (arrhythmias). Some arrhythmias are harmless and do not need treatment. Sometimes arrhythmias stop on their own or with changes in lifestyle, such as avoiding alcohol, caffeine (in beverages and foods), and smoking. Other arrhythmias are dangerous or bothersome enough to need treatment. Antiarrhythmic medications are one type of treatment. Other treatments for arrhythmias include insertion of a pacemaker or an implantable cardioverter-defibrillator (ICD), cardioversion-defibrillation, or destruction of a small area of heart tissue that is responsible for the arrhythmia (ablation).
Antiarrhythmic medications are useful for suppressing fast arrhythmias that cause intolerable symptoms or pose a risk. No single medication suppresses all arrhythmias in all people. Sometimes several medications must be tried until the response is satisfactory. Sometimes antiarrhythmic medications can worsen or even cause arrhythmias. This effect is called proarrhythmia. Antiarrhythmic medications may also cause other side effects.
Antiarrhythmic medications are divided into groups based on how they work. The main groups include beta-blockers, calcium channel blockers, potassium channel blockers, and sodium channel blockers.
Beta-blockers block the effects of the hormone epinephrine (adrenaline). In the heart, this blockade slows the natural pacemaker activity of heart cells and slows conduction of impulses through the heart's normal electrical pathways.
Calcium, potassium, and sodium are electrolytes that flow in and out of heart cells and are responsible for the heart's normal electrical activity. These electrolytes flow through the walls of heart cells through microscopic pores called channels. There are separate channels for each electrolyte. Blocking one of these channels can slow conduction through the heart's electrical system and/or decrease the natural pacemaker activity of heart cells.
Some Medications Used to Treat Arrhythmias
Examples | Some Side Effects | Comments |
|---|---|---|
Beta-blockers | ||
An abnormally slow heart rate (bradycardia) Fatigue Depression Possible masking of low blood sugar levels Impaired circulation in the trunk, arms, and legs Insomnia Sexual dysfunction Shortness of breath Spasm of the airways (bronchospasm) With some beta-blockers, an increase in the triglyceride (a fat) level In people with glaucoma, increased pressure in the eye | These medications are used to treat ventricular premature beats, ventricular tachycardia, ventricular fibrillation, and paroxysmal supraventricular tachycardia. They are also used to slow the ventricular rate (how fast the heart's lower chambers—the ventricles—beat) in people with atrial fibrillation or atrial flutter. People who have asthma should ask their doctor whether the benefits of taking these medications outweigh the harms of worsening their asthma symptoms. | |
Calcium channel blockers | ||
Constipation Diarrhea Low blood pressure Swollen feet | Only certain calcium channel blockers, such as diltiazem and verapamil, are useful for arrhythmias. They are used to slow the ventricular rate in people who have atrial fibrillation or atrial flutter and to treat paroxysmal supraventricular tachycardia. Diltiazem and verapamil slow the conduction of electrical impulses through the atrioventricular node. Certain people with Wolff-Parkinson-White syndrome | |
Nausea Vomiting Serious arrhythmias If the dose is too high, distortion of color vision, making objects appear greenish yellow | Digoxin slows conduction of electrical impulses through the atrioventricular node. Digoxin is used to decrease the ventricular rate in people who have atrial fibrillation or atrial flutter and to treat paroxysmal supraventricular tachycardia. | |
Potassium channel blockers | ||
Azimilide Vernakalant | For all potassium channel blockers: Arrhythmias and low blood pressure | These medications are used to treat ventricular premature beats, ventricular tachycardia, ventricular fibrillation, atrial fibrillation, and atrial flutter. Because amiodarone can be toxic, it is used for long-term treatment only in some people who have serious or very bothersome arrhythmias. Bretylium is used only for short-term treatment of life-threatening ventricular tachycardias. Azimilide and vernakalant are not available in the United States. |
Purine nucleoside | ||
Spasm of the airways Flushing (for a short time) | Adenosine slows conduction of electrical impulses through the atrioventricular node. Adenosine is used to end episodes of paroxysmal supraventricular tachycardia. People who have asthma are not given this medication. | |
Sodium channel blockers | ||
Arrhythmias (which can cause death, particularly in people who have a heart disorder) For some medications: Digestive upset Dizziness Dry mouth Light-headedness Retention of urine Tremor In people with glaucoma, increased pressure in the eyes | These medications slow the conduction of electrical impulses through the heart. These medications are used to treat ventricular premature beats, ventricular tachycardia, and ventricular fibrillation and to convert atrial fibrillation or atrial flutter to normal rhythm (cardioversion). Except for lidocaine and mexiletine, these medications may also be used to prevent episodes of atrial fibrillation or atrial flutter and, less commonly, paroxysmal supraventricular tachycardia. | |
