What is it?
During atrial fibrillation the upper chambers of the heart quiver rapidly instead of their normal pumping action, which may allow blood to stagnate and blood clots to form inside the heart. The majority of blood clots form within a blind-ending pocket (called the appendage) attached to the left upper chamber, as this is where blood is most likely to pool. If a blood clot dislodges and travels to the brain a stroke may result.
Who is at highest risk?
Some people may go through their lives with AF and never have a stroke, but others will. Several characteristics seem to increase a person's risk of having a stroke, including:
- History of high blood pressure, even when treated
- Increasing age (in particular those over 75 years old)
- Having heart failure or weakened heart pump function
- A history of a prior stroke or TIA (transient ischaemic attack).
In general, the more risk factors, the higher the risk of stroke. The risk of having a stroke each year varies from around 1% for people with no risk factors, through to about 17% for a person with all of the characteristics.
People who have the heart rhythm condition atrial fibrillation (AF) or atrial flutter are at higher risk than other people of having a stroke at some point in their life. Unfortunately there are still few effective treatments that will reverse the damage once a stroke has occurred, and so it is important to try to prevent strokes before they happen.
It is not true that the more atrial fibrillation you have, the higher the risk of stroke. A person who has 1 to 2 episodes per year can still have a stroke, whereas another person in "full-time" AF may not.
There are currently 2 options to prevent stroke for people with AF: "blood thinner" medications, or a procedure to seal off the left atrial appendage. Recommended treatments vary according to a person's risk of stroke.
"Blood thinner" medications act to generally reduce the body's ability to make blood clots and must be taken long term. Patients with no risk factors are generally recommended to take Aspirin (or an alternative such as Clopidogrel), while those with more than one risk factor need greater protection and warfarin is the better medication for preventing blood clot formation with AF. Warfarin treatment requires careful monitoring with regular blood tests to keep the levels within a satisfactory range. Some patients may suffer from major internal bleeding while taking warfarin, although the chances of this are very low (1% per year) if the levels are well controlled. The decision to take long term warfarin should be discussed carefully with your doctor.
Left atrial appendage occluder devices are now an accepted alternative treatment to taking warfarin in the long term (although not if you have rheumatic heart valve problems). This involves a keyhole catheterisation procedure to deliver a small "plug" inside the heart to seal off the blind-ending pocket (left atrial appendage) where blood clots are known to form. Once the plug has properly healed af ter around 2 months, warfarin can safely be stopped.
There is of course a small "up front" risk of around 1-2% of having a complication with the procedure, including having major bleeding or a stroke. Patients with atrial fibrillation who are undergoing open heart surgery for any reason may have the left atrial appendage closed off or removed completely by their heart surgeon, to reduce the future risk of stroke.
What about catheter ablation procedures for AF?
There is currently no strong proof that catheter ablation procedures reduce the risk of stroke for people with AF. It is hoped that a completely successful result with the procedures may help prevent stroke for some patients. The role of catheter ablation is to treat the symptoms of AF when incompletely controlled on medications.
For more information
Talk to your family doctor or Cardiologist about your own health situation to better understand your risk of stroke and treatment options.
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Disclaimer: This page has been prepared by Genesis Care for informational purposes only and is not medical advice. All care has been taken to ensure the accuracy of information, however, this information may be changed, improved, or updated without notice.