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 (see Treatment/Drug Therapies) 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). It is often used in combination with Chemical Cardioversion.

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 when you receive the shock. 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 NSR.

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

Low Risk Treatment But High Risk of Clots Forming

Electrical Cardioversion is considered a low risk procedure. But it is a ‘shock’ to the body and requires general anesthesia. (It’s like a mini electrocution. The metal paddles or patches, for example, can potentially leave burn marks on the chest.)

Cardioversion does carry a high risk of forming clots and causing stroke.²

Why? 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 clot can break away and enter the blood stream with the potential of causing a stroke. (The LAA is where most A-Fib clots originate.)

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

While on warfarin (Coumadin), your blood will be tested for how long it takes to clot (a prothrombin time test, PT). The goal is to keep your INR (International Normalized Ratio) score between 2.0 and 3.0. Your dosage will be adjusted if necessary. You may have to have your blood tested weekly until your doctor determines you are in the proper INR range.

Success Rate of Cardioversion

Electrical Cardioversion (often combined with Chemical 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 NSR.

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.⁴

Are Repeated Electrical Conversions Dangerous?

People with A-Fib often ask, “How often can I be Electrical Cardioverted? Does it ever become counterproductive or dangerous?” Right now we just don’t know the answer to this question. Added 11/13/19: Electrocardioversion (DCCV) has been found to be a long-term independent risk factor for: A-Fib recurrence, the need for repeat DCCVs, more hospitalizations, and more ablations. In a study of patients having 2-4 or more than 5 DCCVs (>5), they had higher rates of repeat DCCVs, they were hospitalized more often, and had more ablations. (It makes sense that these patients would have more repeat Electrocardioversions because DCCVs tend not to last very long. And they would have more ablations in order to get rid of their A-Fib and to not have to undergo shocks and hospitalizations.) In these patients, stroke rates did not increase, but 5-year death was increased for patients undergoing >5 DCCVs, though this didn’t reach statistical significance.

What’s the bottom line for you? Electrocardioversions (DCCVs), accompanied by anticoagulation, have been demonstrated to have “no adverse sequela” (bad effects) long term. The effects described above are what you would normally expect: more repeat DCCVs, the return of A-Fib, more hospitalizations, more ablations. But having an Electrocardioversion doesn’t seem to damage one’s heart or be dangerous in itself.

References: Jacobs, V et al. The Impact of Repeated Cardioversions for Atrial Fibrillation on Stroke, Hospitalizations, and Catheter Ablation Outcomes. JAFIB Journal of Atrial Fibrillation. Apr. 30, 2019. 11(6):2164 . https://www.ncbi.nlm.nih.gov/pubmed/31384369  doi: 10.4022/jafib.2164. eCollection 2019 Apr.

Former Senator and NBA basketball player Bill Bradley had three successful Electrical Cardioversions (DCCVs) from 1996-1998 without any apparent ill effects.⁵ 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.⁶

Don’t Be Frightened

Don’t let this type of video 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: Thursday, February 27, 2020

Back to the Top
Return to Treatments for Atrial Fibrillation