Medications for a Heart Arrhythmia: How to Treat an Irregular Heart Rhythm

Antiarrhythmic medication

That occasional heart palpitation you get could be caused by that extra cup of coffee — or it could be a symptom of a serious medical condition known as heart arrhythmia.

Atrial fibrillation is the most common type of heart arrhythmia in the U.S., but there are several others you might not know about.

In this article, we cover the drugs you can use to treat heart arrhythmia. We also explain how each of these drugs work and which type of heart arrhythmias they can address.

What is a Heart Arrhythmia?

A heart arrhythmia is a condition where the heart beats either too slowly, too quickly, or in an erratic pattern.

Under normal circumstances, the heart's rhythm is regulated by electrical impulses originating from its natural pacemaker.

However, in an arrhythmia, these electrical impulses are disrupted. This disruption can be caused by internal issues within the heart's electrical system, or other factors, such as electrolyte imbalances.

In certain cases, perfectly healthy individuals can have an arrhythmia. Common symptoms include palpitations, shortness of breath, weakness, or fatigue.

What are Antiarrhythmic Drugs?

Antiarrhythmic drugs are medications aimed at fixing serious abnormal heart rhythms. They can also be administered if a patient is in cardiac arrest. Some heart rhythms that antiarrhythmic drugs can treat include, but are not limited to the following conditions.

Cardiac arrest rhythms

This condition occurs when the heart stops beating. While the heart may still be generating electrical impulses, immediate medical intervention is crucial, as untreated cardiac arrest leads to death.

These abnormal electrical signals require cardiopulmonary resuscitation (CPR), adrenaline, and/or defibrillation before antiarrhythmic drugs are even considered.


This term refers to a resting heart rate that’s slower than normal, typically lower than 60 beats per minute.

Causes of bradyarrhythmias may include sick sinus syndrome (SSS) — a malfunction of the heart’s pacemaker, where it does not trigger each heartbeat — and heart block — where the electrical signals controlling heart rhythm are delayed or do not reach the bottom heart chambers.


This refers to a group of arrhythmias where the heart beats much faster than normal, and most antiarrhythmic drugs discussed in this article will target these conditions.

Tachyarrhythmias are divided into several subdivisions, including:

Atrial fibrillation

Also known as AFib or AF, atrial fibrillation — also known as AFib or AF — is the most common type of serious heart arrhythmia.

The Centers for Disease Control and Prevention (CDC) estimates that 12.1 million people in the U.S. will be diagnosed with this condition by 2023.

This heart condition causes abnormal quivering of the top chambers of the heart (the atria) which results in abnormal blood flow due to disorganized electrical signals in these chambers. These electrical impulses are typically abnormally fast.

When the heart pumps in this manner, blood may clot as it travels from the heart, and these blood clots can lodge in the brain, resulting in stroke.

To prevent strokes associated with atrial fibrillation, blood thinners such as warfarin or rivaroxaban are used, in addition to the antiarrhythmics we’ll discuss below.

Atrial flutter

This type of heart arrhythmia is characterized by the increased rate in the top chambers of the heart. Atrial flutter is caused by an abnormal electrical circuit in the heart.

Research shows that males are more likely to be affected by atrial flutter.

Supraventricular tachycardia (SVT)

SVT refers to a fast heart rate originating from above the lower chambers of the heart. This condition is typically caused by faulty electrical signaling and it may be triggered by premature heartbeats.

Certain SVTs are hereditary, while others can be caused by lung conditions or lifestyle habits, like smoking, and overconsumption of caffeine and alcohol.

Sinus tachycardia (ST)

People with sinus tachycardia have a regular heart rhythm but a faster heart rate coming from the heart’s natural pacemaker.

While tachycardia (increased heart rate) can be a normal response to exercise, emotional distress, illness, or dehydration, people with sinus tachycardia have higher than normal heart rate even at rest.

How Do Antiarrhythmic Drugs Work?

The purpose of antiarrhythmic drugs can be to slow down or speed up the heart or to fix an irregular rhythm.

Antiarrhythmic drugs aren’t always used for treating arrhythmias; they can also be used to diagnose heart conditions.

When used as a diagnostic tool, antiarrhythmic drugs slow your heart down so that your health care provider can more easily read your electrocardiogram (EKG). These medications are usually only given if you are stable.

If your heartbeat is too slow, strategies like CPR, electrical cardioversion (when a patient is shocked to correct a rhythm, but with less energy than defibrillation), and artificial pacemakers are used.

Heart and pulse monitoring

What are the Different Classes of Antiarrhythmic Drugs?

Class 1: Sodium channel blockers

In order for the heart to effectively pump blood, it needs to first receive the signal to pump. These automatic signals are sent by the heart’s natural pacemaker, which is known as the sinoatrial (SA) node.

The electricity sent from the pacemaker activates sodium channels in the heart’s muscle prompting them to contract and, in turn, regulating the heart’s pumping rate.

Sodium channel blockers prevent the activation of these sodium channels, decreasing the heart rate.

Examples of sodium channel blockers include:

  • Lidocaine (used in cardiac arrest)

  • Procainamide (Procan®), and flecainide (Tambocor®)

These examples are used in different scenarios, but, like most of the medications in this classification, are used to treat abnormally fast heart rhythms. Potential side effects of sodium channel blockers include:

  • Bradycardia (slow heart rhythm)

  • Decreased blood pressure

  • Allergic reactions

  • Cardiac arrest

Class 2: Beta blockers

Beta blockers are medications that target beta-adrenergic receptors These receptors are found throughout the body, including in the airways and the heart. The term “adrenergic” generally refers to a receptor that binds to adrenaline or noradrenaline.

Consider the fight or flight response: in this case, adrenaline stimulates these receptors in your heart, leading to a faster and stronger heartbeat, preparing your body to fight or flee literally. These receptors also function at lower levels when you’re not in stressful situations.

Beta blockers would block the effects that stimulation of these receptors will have, therefore slowing the heart. These are often used as antihypertensive drugs. Additionally, beta blockers have the benefit of slowing the heart down, which decreases the strain on the heart and improves blood flow to the heart. This is especially important after a heart attack.

Examples of beta blockers include:

Potential side effects of beta blockers include:

  • Airway closure, as these medications can block the opening effects of beta receptors in the airway. Consequently, individuals with asthma should avoid this medication

  • Bradycardia

  • Decreased blood pressure

  • Allergic reactions

  • Weakness

  • Cardiac arrest

Class 3: Potassium channel blockers

Potassium channel blockers, as the name would suggest, block potassium channels.

After the heart has received an electrical impulse and sodium channels have opened, the electrical potential inside the cell is abnormal.

In order to remedy this, potassium leaks out of the cell to correct the voltage and set the cell up to receive more messages to contract again so that the heart can continue beating.

By blocking potassium channels, the period in which the heart cannot contract again increases, causing the heart to slow.

Examples of potassium channel blockers include:

  • Amiodarone (commonly used in cardiac arrest rhythms when defibrillation has failed)

  • Sotalol (used for fast rhythms)

  • Dofetilide (Tiksoyn®)

Potential side effects of potassium channel blockers include:

  • Torsade de Pointes: A life-threatening arrhythmia that can progress to ventricular fibrillation and cardiac arrest. This is a serious medical emergency that needs to be addressed quickly to avoid death.

  • Low blood pressure (hypotension)

  • Cardiac arrest

Class 4: Calcium channel blockers

Calcium channel blockers have two subtypes: dihydropyridines (used as antihypertensives) and nondihydropyridines (used as antiarrhythmic drugs).

In this article, we’ll only focus on nondihydropyridines. These medications target the cells in the heart’s pacemaker.

They block calcium channels which act as signals for the pacemaker to send out another beat to the rest of the heart.

By blocking these signals, subsequent heartbeats take longer to occur and thus the heart rate is slowed.

Examples of calcium channel blockers include:

  • Diltiazem (Cardizem®, and Dilcaor XR®)

  • Verapamil (Clan®, Verelan®, and Isotpin SR®)

Potential side effects of calcium channel blockers include:

  • Heart failure

  • Bradycardia

  • Low blood pressure (hypotension)

Class 5: Variable mechanism (unclassified antiarrhythmics)

These medications have varied mechanisms of action and therefore do not fit into any specific category.

Examples of unclassified antiarrhythmics include:

  • Digoxin: This is used to treat heart failure and supraventricular arrhythmias. Brand names include Lanoxin® and Digitek®.

  • Adenosine: This is administered in emergencies to decrease heart rate so that a diagnosis can be made on an EKG, or in some cases, it is used to correct abnormally fast rhythms as well. Brand names include Adenocard® and Adenoscan®.

  • Atropine: This increases heart rate in bradyarrhythmias. It is often referred to simply as Atropine.

The side effects of unclassified drugs can vary widely depending on the specific drug you’re using

What are the Benefits of Using Antiarrhythmic Medications?

The main purpose of antiarrhythmic medications is to treat and prevent abnormal heart rhythms.

Here’s a closer look at how the drugs we’ve listed in this article can benefit you:

  • Antiarrhythmic drugs can correct potentially dangerous heart rhythms, improving your overall quality of life.

  • They may decrease the symptoms associated with heart palpitations.

  • Some of these medications can lower blood pressure.

  • Antiarrhythmic drugs can be immediately life-saving, especially when used to address cardiac arrest rhythms.

  • These medications, especially beta-blockers, can improve blood flow to the coronary arteries supplying the heart (especially beta-blockers). This is important after heart attacks, when blood flow is reduced.

A woman having a heart attack.

Medications for Heart Arrhythmia: Special Precautions

Heart arrhythmia medications are complex and have the potential to be life-saving. However, they all have mechanisms of action that require extensive expertise for proper use.

None of these medications can be safely used without a specialist health care consultation, and, in the case of emergencies, an advanced cardiac life support (ACLS) provider.

Never attempt to use any of the medications listed in this article without consulting your health care provider first.

Who should not be taking these medications?

These medications should only be used by people with serious heart arrhythmias. Some medications, such as beta-blockers, have specific cases where they may not be used — including in acute heart failure and asthmatics.

As mentioned before, a comprehensive specialist consultation needs to be done prior to the initiation of these drugs, unless they are started by an ACLS provider during emergencies.

What are some alternative treatments or therapies?

Heart arrhythmia medications can only be prescribed by your doctor, and they may not be suitable for everyone.

If you have an abnormal heart rhythm, your doctor or health care provider may use one of the alternatives listed below.

  • During cardiac arrest, CPR, defibrillation, and adrenaline administration may be used.

  • For certain arrhythmias, your healthcare provider may perform a specific set of procedures called vagal maneuvers to try to correct abnormal heart rhythms.

  • In an emergency where the heart rate is more than 150 beats per minute and a person’s condition is unstable, they’ll initially be given an electric shock using a defibrillator in a procedure known as synchronized cardioversion. In these cases, medication is not usually the first-line treatment.

  • If your heart is beating too slowly and first-line antiarrhythmics (like Atropine) are not working, you may need a pacemaker.

  • For atrial fibrillation, blood thinners are used to decrease the risk of stroke. If warfarin is used, frequent blood tests need to be done to determine whether the blood has not been thinned enough or thinned too much. The blood test usually conducted is known as the International Normalised Ratio (INR). Consult your doctor for more information.

Where Can I Learn More About Medication for Heart Arrhythmia?

If you suspect you have an abnormal heart rhythm that you need treatment for, visit LifeMD.

A team of healthcare professionals can help diagnose and treat your condition to prevent long-term complications.

Book your appointment today to get started.

Jennifer McMillan, APRN, FNP-BC

Jennifer is a board-certified, multistate licensed Nurse Practitioner with over 25 years experience in healthcare. She specializes in Women and Men’s Health, Psychiatry, and Urgent Care. She enjoys including her patients in the decision-making process regarding their care to help them reach and maintain their health goals. In her free time, Jennifer enjoys doing volunteer work at the American Heart Association.

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This article is intended for informational purposes only and should not be considered medical advice. Consult a healthcare professional or call a doctor in the case of a medical emergency.

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