Atrial Fibrillation

Atrial Fibrillation (AF) is a complicated condition to try to explain so we have tried to keep this article as simple as possible. The links at the bottom of the page offer more detail for those seeking a more complete knowledge of the subject.

So, what is AF?

Essentially, the atria (top part of the heart) beat too quickly and the ventricles (main pumping part of the heart) are unable to keep up. This leads to an irregular pulse.

Common symptoms include an irregular pulse, shortness of breath, dizziness, palpitations and chest pain. If you get any of these you should see a doctor at once. Many patients (particularly the elderly) have no symptoms at all.

Atrial fibrillation has many causes - the most common are ageing, high blood pressure, coronary heart disease, and thyroid disease. Very often, we are unable to identify a cause for a particular patient.

In some patients, the heart beat is irregular all the time and in others there are periods of time when the heart beat is normal. This latter condition is called paroxysmal atrial fibrillation.

AF is important as we need to identify and treat any possible causes. The symptoms can be distressing and may need to be treated in some patients.

Commonly, treatment for AF depends on drugs to slow the heart rate down such as digoxin. This does not cure the condition (which often cannot be cured) but does reduce symptoms.

Some people, usually those with a known cause for the condition, can be cured with long term amiodarone and yet others, usually with paroxysmal AF may be offered flecainide tablets to take if symptoms are severe. All of these treatments will usually be recommended by a specialist.

Occasionally a procedure called cardioversion is used to correct the condition. This involves either an injection of medication or administering a controlled electric shock to the chest. These are not suitable for many patients and again the decision to use them is usually made by a specialist.

Once the symptoms are controlled, most patients have very few problems.

What about warfarin?

AF does, however, have another major problem associated with it though. Because the heart beat is irregular, it is not efficient and blood can pool in the atria of the heart. This blood can clot and small pieces often break off, causing a high risk of strokes. This risk is about 5% or 1 in 20 per year for those who have never had a stroke and 12% or 1:9 for those who have had one or more strokes.

Until recently, there was a lot of debate in medical circles over whether Aspirin or Warfarin was the best treatment to prevent strokes in patients with AF. Aspirin is convenient but less effective and may cause stomach ulcers. Warfarin needs regular blood testing (see our anticoagulants page) and carries an increased risk of bleeding.

Overall, warfarin is safer, with more strokes prevented than serious problems caused.

We are often asked how much safer warfarin is than Aspirin. The best evidence available suggests that if 35 people change from aspirin to warfarin, one will have a stroke prevented because of taking the warfarin every 2.2 years (this was the study period). The longer treatment continues, the more people benefit. A high quality analysis of the data can be found on the medical evidence research site Bandolier - Antithrombolytics and stroke in AF

Further information:

Atrial Fibrillation: Emedicine.com - this is a scholarly article on the level of a medical textbook. It is written for doctors but is a total guide if you need it.
Atrial Fibrillation: Patient.co.uk - this is a patient information leaflet similar to the text above but with diagrams and much more detail.
Atrial Fibrillation: New Zealand National Heart Foundation web site. Somewhat limited detail but does have links to more treatment options than we have explored here.