EKG display of heart in A-Fib

Cardioversion for Atrial Fibrillation

Your doctor may recommend a cardioversion to restore your heart to normal sinus rhythm (NSR). There are two types of cardioversion: chemical and electrical. Cardioversion through the use of drugs is called chemical cardioversion. Electrical cardioversion uses a low-voltage, timed electrical shock to restore normal rhythm.

Most cardioversions are planned and scheduled several weeks in advance.

On the other hand, if your A-Fib is so irregular and rapid that it is life threatening, you may be sent to the emergency room, given the intravenous anticoagulant Heparin, and an electrical cardioversion performed.

CHEMICAL CARDIOVERSION

The goal of chemical cardioversion is to make your heart beat regularly (in normal sinus rhythm). It is usually done in a hospital. Some combination of medications is administered intravenously, such as Cardizem, verapamil, ibutilide, adenosine (a class V antiarrhythmic agent) or Procainamide. Doctors monitor you closely for adverse side effects.

Chemical cardioversion is often done in combination with Electrical Cardioversion described below.

Electrical Cardioversion

Electrical Cardioversion is a medical term for giving your heart a low-voltage electrical shock to synchronize it, that is, to make it beat regularly (in normal sinus rhythm).

Note: Electrical cardioversion is not the same as Defibrillation. In defibrillation, doctors use high-voltage shocks to treat life-threatening arrhythmias or a heart that has stopped.

During Electrical Cardioversion you are anesthetized and are unconscious. The cardioversion is performed using a short, controlled electrical shock delivered through pads placed on the chest or both the chest and back. The shock causes the signal producing areas of your heart to discharge all at once. This stops all electrical activity in your heart momentarily, hopefully allowing your normal heart rhythm to take over. Usually only one shock is required to restore normal sinus rhythm.

The electric shock used in cardioversion can cause mild skin burns or redness where the pads contact the chest. Most discomfort is prevented by applying conductive gel and ensuring proper pad placement. Some patients describe brief chest soreness or tingling after the procedure. These effects are usually minor and fade within a few days.

VIDEO 1: Patient video, short animation (:60) explaining the steps in performing an electrical cardioversion for patients in Atrial Fibrillation; YouTube video posted by eMedTV;

Low Risk Treatment But High Risk of Clots Forming

Electrical Cardioversion is considered a low risk procedure. While this procedure often restores a normal rhythm, it carries specific risks involving blood clots, abnormal heart rhythms, and minor skin injury from the shock pads.

When the heart beats irregularly, blood can pool in the atria and form clots. An Electrical cardioversion “stuns” your heart along with your Left Arial Appendage (LAA). Clots may form in the LAA while your heart is stunned and not beating. (The LAA is where most A-Fib clots originate.) The clot can break away and enter the blood stream, then travel to the brain and cause a stroke.

To dissolve potential clots, your doctor will have you take an anticoagulant before the treatment and in the three to four weeks following treatment.

Patients with atrial fibrillation lasting more than 48 hours face a higher risk of clot-related complications. In some cases, a transesophageal echocardiogram (TEE) is used to check for clots in the heart before proceeding.

Success Rate of Cardioversion

Electrical Cardioversion is considered a standard, routine, low risk treatment option, particularly for recent-onset A-Fib patients. If your A-Fib has just started, it may be a momentary aberration; and an Electrical Cardioversion may correct it.

Cardioversion has a very high initial success rate, returning up to 95% of A-Fib patients to normal sinus rhythm (NSR).

High Success Rate, but High A-Fib Recurrence Rate, Too: While the conversion rate is high, recurrence of A-Fib is high too.

Cardioversion doesn’t prevent future episodes of A-Fib. As few as 23% of patients remain in normal sinus rhythm for more than one year post-procedure. For most, their A-Fib returns within the first five days.

Are Repeated Electrical Conversions Dangerous?

People with A-Fib often ask, “How often can I be electrically cardioverted? Does it ever become counterproductive or dangerous?”

In a study of patients having 2–5 or more Electrocardioversions, patients had higher rates of repeat Electrocardioversions, were hospitalized more often, and had more catheter ablations. Though the stroke risk in these patients did not increase.

What’s the Bottom Line for You? Electrocardioversions, accompanied by anticoagulation, have been demonstrated to have no bad effects long term. (I’ve heard of an A-Fib patient who received an Electrical Cardioversion once a month for a year without any apparent problems.)

VIDEO 2: Watch an actual electrical cardioversion. To demonstrate both the ease and safety of this procedure, Dr. Bruce Janiak, a 74 year old full-time emergency medicine physician, had the E.R. staff videotape his cardioversion. 15:08 min. 

Don’t Be Frightened

Don’t let the videos frighten you. It may look and sound traumatic, but Electrical Cardioversion is in fact non-invasive and is one of the easiest and safest short term treatments available for A-Fib.

And don’t let TV shows with emergency room scenes frighten you either. In fact, those scenes are usually depicting defibrillation, not cardioversion (defibrillators use high-voltage shocks to treat a heart that has stopped beating).

In her Personal Experiences story, Kris tells of accidentally being awake during an electrical cardioversion (see Personal Experiences story #37). According to Kris, the shock is relatively mild compared to what you often see portrayed in medical dramas on TV.

Last updated: Tuesday, September 1, 2026

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