Atrial Fibrillation

This is a an information sheet I have developed for my patients. You may print this, as required, for personal use only. No changes to the document are allowed.

What is atrial fibrillation?

The heart has an electrical system to maintain efficient function of the heart. A car engine also has an electrical system to make sure it runs smoothly. Sometimes, abnormal electrical circuits can develop and are the cause of atrial fibrillation. Atrial fibrillation is the term used to describe one of these rhythm disturbances.

Atrial fibrillation affects the normal function of the heart

In atrial fibrillation the back chamber of the heart is much less efficient at pumping blood. In many but not all persons, the heart will race when it goes out of rhythm. Patients can become aware of the heart beating erratically or rapidly. Medication can be used to slow the heart and this can abolish all symptoms related to the heart being out of rhythm.

Causes of atrial fibrillation

The heart can go out of rhythm even if there is no detectable abnormality. However, in many patients who have had high blood pressure of many years, the back chamber of the heart gets enlarged and this creates the conditions that can result in the heart going out of rhythm. Many other conditions can cause the heart to go out of rhythm, usually also because there is enlargement of the back chamber of the heart.

Potential advantages of getting the heart back into normal rhythm

Some patients feel a lot better when the heart is in normal rhythm- the heart rate is slower and they stop having palpitations or feeling short of breath when exerting themselves. On the other hand, with the help of medication we can prevent the heart from racing and this prevents problems with palpitations or shortness of breath. If the heart remains out of rhythm it is important to make sure that the heart is not racing and medication is often required to control this.

Increased risk of stroke with development of atrial fibrillation

When the heart is out of rhythm in this way, the back chamber is less efficient at pumping blood even if the main pumping chamber is strong. This can allow blood to stagnate in pockets within the back chamber of the heart (within the left atrium) and small clots can form. If these clots break and travel with the blood to the brain then a person may suffer a stroke. Sometime the clot breaks up quickly and the person has a complete recovery- in lay terms this is sometimes refered to as a "transient stroke" or "mini-stroke". Less commonly the clot travels to the arm or leg or other places and causes different problems.

Good studies show that if atrial fibrillation develops then the risk of stroke increases- but that by taking warfarin the risk is reduced by about eighty 80 percent.

Reducing the risk of stroke with atrial fibrillation

The risk of stroke has been shown to be higher in some patients than others. Those who have high blood pressure, who have a weak heart, who have an enlarged back chamber of the heart, or those who have already had a stroke or "transient stoke" are at higher risk and benefit more from taking warfarin.

Restoring normal heart rhythm

The heart may go back into rhythm by itself, with the use of medication, or after administration of an electrical shock by your specialist. In many patients the heart may go out of rhythm again, some patients require medication to keep the heart in normal rhythm.

Maintaining normal heart rhythm

The chances are different for different people. In some people the chance of success is high (90%) and in other low (about 50%). Some people can remain in normal rhythm for many years while others may find their heart goes out of rhythm after a short time.

Warfarin, in most instances, should be continued even if normal heart rhythm is restored

In the past most patients were only treated with warfarin for three weeks after the heart was successfully put back into normal rhythm. But studies and our own observations showed that in some patients we are better advised to continue warfarin for longer.

We know that if the heart goes out of rhythm again for more than two days, and warfarin as been stopped, that the risk of clot forming increases again. Since we can not accurately predict if the heart will go out of rhythm again, in high risk patients, we might continue with warfarin for a longer period. The recommended duration of treatment with warfarin is different for different persons. Some doctors are more in favour of a longer period of treatment with warfarin.

Potential disadvantages of restoring normal heart rhythm

In some people whose heart has been out of rhythm for some time, or who have had several episodes of the heart going out of rhythm, the only way of keeping the heart in rhythm is to use medication. Some of the more powerful medication can sometimes cause serious side-effects.

Accepting atrial fibrillation will persist and not attempting to restore normal heart rhythm

In many persons this might be the best option especially if warfarin treatment is continued. By this means the risk of stroke is reduced and there is no need to take strong heart rhythm drugs. This is not a good option for those persons that do not tolerate atrial fibrillation well, either because it causes palpitations or because it makes them too short of breath.

Risks of bleeding complications with Warfarin

Because the blood's ability to clot is reduced with warfarin, it is important to have blood tests to make sure the blood is not too "thin'. Many medications can interfere with warfarin and it is important to make sure new medication, including some antibiotics, will not interfere with warfarin or that some adjustment is made to the dosage of warfarin. Certain drugs which increase risk of developing stomach ulcers (anti-inflammatory medications) should not be taken.

Studies do suggest there is an increased risk of bleeding if warfarin is being taken, but in most instances the benefits outweigh this risk.

Dr Hitesh Patel, Cardiologist
Suite 3, level 2
Ascot Integrated Hospital
90 Greenlane Rd East
REMUERA.
Phone 5209399

April, 2007