Tests for and complications of atrial fibrillation

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Are any tests needed?

A 'heart tracing' called an electrocardiogram (ECG) can confirm the diagnosis. This test can also rule out other causes of an erratic or fast heart rate.
Other tests such as blood tests and an echocardiogram (ultrasound scan of the heart) may be advised. These tests look for an underlying cause of AF such as a heart problem or an overactive thyroid gland.
Often an underlying cause is already known about. For example, you may already have angina. You may not need any further tests if AF develops as a complication.

What are the possible complications of atrial fibrillation?

An increased risk of having a stroke

The main complication of AF is an increased risk of having a stroke. AF causes turbulent blood flow in the heart chambers. This sometimes leads to a small blood clot forming in a heart chamber. A clot can travel in the blood vessels until it gets stuck in a smaller blood vessel in the brain. Part of the blood supply to the brain may then be cut off, which causes a stroke. The risk of developing a blood clot and having a stroke varies, depending on various factors. The level of risk is divided into three categories: high, medium and low risk.

High risk means that, without treatment, you have about a 6-12 in 100 chance (sometimes higher) of having a stroke in the next year. People in the high risk group include those:

o who have already had a stroke or known blood clot, or
o are aged 75 years or older who also have one of the following 'risk factors': high blood pressure, diabetes or a cardiovascular disease (such as angina, heart attack, peripheral vascular disease), or
o who have a heart valve problem, or
o who have heart failure or poor heart function shown on a heart scan.

Moderate risk means that you have about a 3-5 in 100 chance of having a stroke in the next year. People in the moderate risk group include those:

o aged 65 years or older (with no high risk factors), or
o who are of any age (up to age 75 when the risk is high) but who also have one of the following 'risk factors': high blood pressure, diabetes or a cardiovascular disease (such as angina, heart attack, peripheral vascular disease).

Low risk means that you have about a 1-2 in 100 chance or less of having a stroke in the next year. People in the low risk group are all people with AF aged less than 65 and who do not have any risk factors that put them in the high or moderate risk category.

Other complications

Less common complications of AF include the following:

Heart failure develops in some cases. See separate leaflet called 'Heart Failure'.
Cardiomyopathy. There are various causes of cardiomyopathy and AF with a fast heart rate is an uncommon cause. Cardiomyopathy means "weakness of the heart muscle". The reason why cardiomyopathy should develop in some people with AF is not clear.
Angina pains may get worse if you have angina.