How Well It Works

The success of electrical cardioversion depends on how long you have had atrial fibrillation and what is causing it.

After this treatment, about 9 out of 10 people get back a normal heart rhythm right away.^{footnote 1} But for many people, atrial fibrillation returns. Normal rhythm may last less than a day or for weeks or months. It depends on your other health problems.

Staying in a normal rhythm is more likely when the cause of your rhythm problem is not another heart problem. But for most people, atrial fibrillation is caused by another heart problem and is very likely to return.

If your atrial fibrillation returns, you may be able to have cardioversion again. But you might not stay in a normal rhythm for very long. If atrial fibrillation comes back quickly (within a week or so), having cardioversion a third time, or more, is less likely to help you. Your doctor might recommend a different treatment, such as a rhythm-control medicine, to get your heart rhythm back to normal.

If you take antiarrhythmic medicines too, they can help you stay in a normal rhythm longer.

Cardioversion may be less successful or may not be recommended if you:

• Have had atrial fibrillation for more than a year.
• Have significant valve problems.
• Have an enlarged heart as a result of heart failure or cardiomyopathy.
• Have multiple recurrences of atrial fibrillation.

Cardioversion is more likely to be successful if:

• Atrial fibrillation has been present for less than a year.
• This is your first episode of atrial fibrillation.
• You are young.
• Antiarrhythmic medicines are used along with cardioversion.