Cardioversion is a very safe and effective treatment for atrial fibrillation and atrial flutter. However, there are some potential complications.
- Stroke (or embolism) is perhaps the most dreaded complication. This is where a blood clot is dislodged from the heart into the blood stream. If the clot travels to a major organ it can cause problems such as a stroke or heart attack. For this reason if the atrial fibrillation has been present for more than 48 hours, or its duration is unknown, either the blood must be thinned using warfarin for at least 3 weeks or you must undergo transoesophageal echocardiogram (TOE) examination prior to the cardioversion.
- If adequate blood thinning is undertaken the risk of an embolus or a stroke is less than 1:1000.
- Depending on how long you have been in atrial fibrillation or flutter, your normal pacemaker may not function immediately on terminating the abnormal rhythm. Usually this recovers promptly but in rare cases temporary and sometimes permanent pacemakers may need to be inserted.
- Finally, there is a very small risk associated with the administration of the sedation required for the cardioversion, but the likelihood of a significant anaesthetic complication is also less than 1:1000.
How successful are cardioversions?
Cardioversion doesn’t always restore normal heart rhythm. Sometimes it’s successful to start with, but then your abnormal heart rhythm comes back several days, weeks or even months later. If this happens, your doctor may want to repeat the cardioversion or they may consider another treatment for you.