Using Electrical Cardioversion for Atrial Fibrillation
Electrical cardioversion is a process by which the heart is shocked to convert it from an irregular rhythm back into a normal sinus rhythm. The EKG illustration shows what the heart rhythm looks like before and after cardioversion.
For patients in persistent or permanent atrial fibrillation, electrical cardioversion may be done early in the process to stop the afib and put the heart back into sinus rhythm. For other afib patients, electrical cardioversion may not be tried until later, when medication has stopped working. Electrical cardioversion has a low success rate, and may require multiple tries. It also doesn't cure afib.
What to Expect From Electrical Cardioversion
Cardioversion
Images courtesy of AtriCure, Inc.
What should you expect if you are going to have an electrical cardioversion? First, to avoid having blood clots break free during this procedure, you may take anticoagulants (warfarin or Coumadin®) for one to two months before the procedure to eliminate your risk of blood clots. If you can't take anticoagulants, you may have a transesophogeal echocardiogram (TEE) in which you swallow a narrow tube with a camera that makes ultrasound images of the heart to ensure that your heart doesn't contain any blood clots.
Mostly likely your doctor will tell you not to have anything by mouth after midnight the night before the procedure.
You will have your electrical cardioversion in the electrophysiology (EP) lab or suite. Once you arrive, you will be fitted with an IV for receiving medications and fluids and connected to monitors so the doctor can see what is happening with you. When it's time for the procedure to begin, you'll be given a medication via IV to put you to sleep.
Once you're asleep, the doctor will use the defibrillator/cardioverter/pacemaker machine to give your heart a jolt of energy that will be delivered through paddles or EKG-type patches placed on the front and back of the chest. This electric shock should restore your normal heart rhythm, and may take several tries.
If external cardioversion fails, then internal cardioversion may be done and involves delivering the jolt of energy through catheters inside the heart.
Once you wake up following the electrical cardioversion, you can go home, but will need to have someone drive you. For a few days following the procedure, you may find that your chest is tender.
After the electrical cardioversion, you will be on a rhythm control medication to keep the heart in normal sinus rhythm. You will also remain on an anticoagulant, such as warfarin or Coumadin®, to prevent blood clots.
Risks from Electrical Cardioversion
Electrical cardioversion risks include skin burns, fluid in the lungs, heart attack, stroke, or even death, though that is very rare.
Success Rates for Electrical Cardioversion
Various studies have reported that electrical cardioversion is over 90 percent effective in converting to a normal sinus rhythm, and that the success is enhanced when patients are on an antiarrhythmic beforehand, which helps prevent reverting back to afib. 1
Success depends on the size of the left atrium as well as how long the patient has been in afib. Patients with a very large left atrium, one greater than 5 cm, or who have been in constant afib for a year or two, may not be effective in being converted to or maintaining a normal sinus rhythm.1
Following a successful electrical cardioversion, the goal is to maintain a normal sinus rhythm, which only happens with about 20-30 percent of patients within the first year if they are not on rhythm control drugs. Overall, the likelihood is quite high that you will revert back into atrial fibrillation, regardless of whether you stay on rhythm control drugs.
Several patients that we spoke with had an electrical cardioversion, but for them the procedure was not successful in converting them to a normal sinus rhythm or in maintaining it.
When neither medication nor electrical cardioversion yields long-term success, then catheter ablation or surgical ablation may be next for consideration in an attempt to manage and cure your afib. For more information about these procedures, see Can Afib Be Cured?
1 Russo, Andrea M., MD, "Overview of the Contemporary Evaluation and Management of Patients with Atrial Fibrillation: What Every General Practitioner Should Know" <http://www.americanheart.org/downloadable/heart/1075_russo.pdf>, American Heart Association [Internet], Copyright, 2006.
