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Atrial Fibrillation is most likely a result of a combination of genetic, lifestyle and environmental factors. Knowing your genetic risk is knowing more about your overall risk for this disease.

The deCODEme Complete Scan analyzes your DNA for known genetic risk variants and provides you with a personalized interpretation of your genetic risk for Atrial Fibrillation.

deCODEme unlocks the information stored in your DNA and provides you with a personalized interpretation of your genetic risk for Atrial Fibrillation

Atrial fibrillation is the most common heart-rhythm disturbance

An estimated 2.3 million American adults have been diagnosed with atrial fibrillation and the risk of developing this condition at any time after the age of 40 has been found to be 20-25% in individuals of European and East Asian descent.

The irregular and often rapid heart rate can result in poor blood flow

Atrial fibrillation is caused by disruption of the normal functioning of the electrical system in the atria, the two upper chambers of the heart. Normally the electrical system stimulates the atria to contract regularly and in coordination with the ventricles, the lower chambers of heart. In atrial fibrillation the atria are stimulated to contract very irregularly and rapidly, up to 350 to 600 times per minute. This results in ineffective and uncoordinated contraction of the atria – the atria essentially quiver instead of contracting. Although a natural checkpoint between the upper and lower chambers protects the ventricles from overstimulation, the contraction rate of the ventricles (which is the same is the actual heart rate or pulse) is still irregular in atrial fibrillation and can be up to 220 beats per minute when not treated. Occasionally the pulse rate is very slow, necessitating pacemaker placement.

Symptoms range from none to serious discomfort

It is possible to have atrial fibrillation without feeling the symptoms generally associated with this condition. Usually, the symptoms of atrial fibrillation include heart palpitations, fatigue, dizziness, tightness in the chest and shortness of breath. Atrial fibrillation can also worsen symptoms due to other heart diseases such as heart failure and coronary artery disease. Some individuals are always in atrial fibrillation (chronic or permanent atrial fibrillation) while others have episodes of the condition.

Genetics contribute significantly to the risk of atrial fibrillation

Genetic variants are known to contribute to the risk of atrial fibrillation and up to a third of patients with AF have a family history of the disease. Scientist at deCODE genetics have discovered common genetic variants that increase the risk of AF; near the PITX2 gene on chromosome 4 and in the ZFHX3 gene on chromosome 16.

deCODEme calculates your genetic risk of atrial fibrillation

The deCODEme Complete Scan identifies validated AF risk variants and uses them to provide a personalized interpretation of the associated genetic risk for AF. The number of variants included in the deCODEme Complete Scan for each ethnic group are listed in the table below.

	Number of Variants Measured
European ancestry	5
East Asian ancestry	1

At present, the necessary scientific information to interpret the genetic risk for individuals of other ethnicities is not available. This information will be added as soon as it becomes available and we are assured of its quality.

Who is at increased risk for atrial fibrillation?

Although atrial fibrillation mostly occurs as a result of another cardiac condition, other known risk factors for developing atrial fibrillation include:

• Age: Atrial fibrillation becomes significantly more common with increasing age. It is relatively rare in individuals younger than 60 (less than 1%) but common in those older than 80 (over 10% in Caucasians).
• Cardiovascular disorders: High blood pressure is the most common condition associated with atrial fibrillation and is a very important risk factor. Heart failure and heart valve disease are other disorders often associated with atrial fibrillation and it is also very commonly seen following heart surgery.
• Several other conditions are known to cause episodes of atrial fibrillation. These include hyperthyroidism (overactive thyroid), pulmonary embolus (blood clot in the lung), alcohol, stimulants such as cocaine or decongestants, surgeries, infections and other acute illnesses. Other factors that have been shown to increase the risk of atrial fibrillation include obesity and the sleep apnea syndrome.
• Genetics: Several distinct regions of the genome and gene mutations have been linked to atrial fibrillation in individuals and families but these appear to be rare causes. On the other hand, common genetic variants have been identified on chromosome 4 that increase the general population risk of developing atrial fibrillation.

A heart-healthy lifestyle can prevent atrial fibrillation

Prevention of atrial fibrillation is a challenging task. Steps to take to decrease the likelihood of developing atrial fibrillation include maintaining a healthy weight, avoiding stimulants and using alcohol in moderation. Optimal management of high blood pressure and other heart disorders will help prevent atrial fibrillation and certain medications can be used to decrease its incidence after heart surgery.

Treatment depends on severity and frequency of symptoms

The feared complication of atrial fibrillation is stroke. The electrical disturbance and quivering of the atria promote blood clot formation in the upper chambers of the heart. If a clot forms, the danger is that the clot, or parts of it, can travel with the bloodstream to the brain or other organs (embolize). An embolic stroke will occur if the clot blocks one of the arteries supplying blood to the brain. Compared to other types of strokes, embolic strokes are generally more severe and more commonly recur. Atrial fibrillation is associated with a significant four to five-fold increase in the risk of stroke and accounts for one third of all strokes in patients older than 65.

The main goal of treatment is to prevent stroke

The goals of atrial fibrillation treatment include stroke prevention, restoration of normal heart rhythm and heart rate control. The treatment can be challenging and should be designed to meet the needs of each individual patient. The specific type of treatment depends on the contributing causes of atrial fibrillation, coexisting heart disease, if the disease is episodic or permanent and if the symptoms are interfering with daily activities and quality of life. Restoration of normal heart rhythm is often not possible. Anticoagulation (thinning of the blood) for stroke prevention is generally recommended for all patients older than 65 as well as younger patients who also have hypertension or other cardiovascular diseases.

More information

• The American Heart Association on Atrial Fibrillation
• MedlinePlus – Trusted Health Information for You on Atrial Fibrillation
• National Heart, Lung, and Blood Institute on Atrial Fibrillation

Scientific references

1. Ellinor, P.T., Yi, B.A, & MacRae, C.A.(2008). Genetics of atrial fibrillation.Medical Clinics Of North America, 92(1), 41-51.
2. Holm, H., Gudbjartsson, D.F., Arnar, D.O., et al. (2010). Several common variants modulate heart rate, PR interval and QRS duration.Nature Genetics, Published online: 10 January 2010
3. Kannel, W.B.& Benjamin, E.J.(2008). Status of the epidemiology of atrial fibrillation. Medical Clinics Of North America,92(1), 17-40.
4. Lip, G.Y., Tse, H.F.(2007). Management of atrial fibrillation. Lancet, 370(9587), 604-618.
5. Markides, V.& Schilling, R.J.(2003). Atrial fibrillation: classification, pathophysiology, mechanisms and drug treatment. Heart, 89(8), 939-943.

This content was last reviewed on February 16, 2012.

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