Heart Disease - Atrial fibrillation - - Heart and Stroke Foundation of Ontario

Atrial fibrillation

Atrial fibrillation (AF) is a condition involving an irregular heart rhythm, known as an arrhythmia. It is the most common type of arrhythmia, affecting approximately 250,000 Canadians. While it is rare in people under 40, its prevalence increases with age. About 3% of the population over the age of 45 and 6% over age 65 have atrial fibrillation. After the age of 55, the incidence of AF doubles with each decade of life.

Generally, the risk of developing AF increases with age and with other risk factors such as diabetes, high blood pressure, and underlying heart disease. One of the main complications of atrial fibrillation is stroke. Individuals with atrial fibrillation have a risk of stroke that is 3 to 5 times greater than those without AF.

What is atrial fibrillation?

"Atrial" refers to the top two chambers of the heart known as the atria, where the irregularity in atrial fibrillation occurs. Atrial fibrillation falls under a larger category of illnesses called arrhythmias, which are electrical disturbances of the heart. Arrhythmias can also occur in the ventricles, the two chambers below the atria, and these tend to be more serious than arrhythmias affecting the atria.

The atria (the heart’s “collecting chambers”) are designed to send blood efficiently and rhythmically into the ventricles (the “pumping chambers”) by way of regular electrical signals. From there, blood is pumped to the rest of the body. In atrial fibrillation, the electrical signals are rapid, irregular and disorganized, and the heart may not pump as efficiently.

Atrial fibrillation can cause the heart to beat very fast, sometimes more than 150 beats per minute. A faster than normal heartbeat is known as tachycardia.

Read more about the anatomy of the heart.

Although untreated atrial fibrillation can cause considerable impairment of quality of life, the majority of patients with AF lead active, normal lives with treatment. Be sure to consult your doctor if you have atrial fibrillation but continue to feel unwell.

Atrial fibrillation (AF) has different forms

Paroxysmal Paroxysmal AF is a temporary, sometimes recurrent condition. It can start suddenly and then the heart returns to a normal beat on its own, usually within 24 hours, without medical assistance.
Persistent If you have had atrial fibrillation for more than seven days, this is considered persistent AF. With this type of AF, the heart continues to beat irregularly, and will require either medical or electrical intervention to return the heart to a normal rhythm.
Permanent In permanent AF, the irregular beating of the heart lasts for more than a year when medications and other treatments have failed. Some patients with permanent AF do not feel any symptoms nor do they require any medications.

What causes atrial fibrillation?

Quite often, the cause of atrial fibrillation is not known. Here are a few conditions that might lead to AF:

High blood pressure, the most common cause

Abnormal structure of the heart

Infection or inflammation of the heart (myocarditis or pericarditis)

Diseases that damage the valves of the heart

Overactive thyroid (hyperthyroidism)

A blood clot in the lung (pulmonary embolism)

Congenital heart disease

Excessive use of alcohol

How do I know if I have atrial fibrillation?

Some people with atrial fibrillation may feel perfectly fine. They may not know they have the condition until they have a routine test called an electrocardiogram (described below). Others with atrial fibrillation may experience various symptoms including:

Irregular and fast heartbeat
Heart palpitations or a rapid thumping in the chest
Chest discomfort, chest pain or pressure
Shortness of breath, particularly with exertion or anxiety
Fatigue
Dizziness, sweating, or nausea
Lightheadedness or fainting

How is atrial fibrillation diagnosed?

If your pulse is fast and your heartbeat is irregular, your doctor may have you checked for atrial fibrillation. Your doctor will take your medical history, and will ask you for details about your condition and risk factors. Questions may include: How long have you had symptoms? Describe your symptoms. Do they come and go? Do you have other medical conditions? How much alcohol do you drink? Your doctor will also ask you whether anyone in your family has atrial fibrillation, and whether you have heart disease or a thyroid condition. Your age is also a factor to take into consideration, as AF is more common in older people.

Stethoscope Using a stethoscope, your doctor will listen for fast, irregular beats. Your doctor will also check your pulse and determine whether or not it is normal.

To hear what atrial fibrillation sounds like, listen to this sound file.

Electrocardiogram The main diagnostic test is an electrocardiogram (ECG), which is a painless procedure performed in a clinical setting. Small electrodes are attached to your arms, legs, and chest, and the machine charts the electrical activity of your heart. Your doctor can determine what type of arrythmia is causing an irregular heartbeat from the printout provided by the electrocardiogram. Read more about electrocardiogram.

Echocardiogram A painless procedure, an echocardiogram uses sound waves to make a picture of your heart. Read more about echocardiogram.

Holter monitor To test the rhythm of your heart while you do regular daily activities, you may be asked to wear a Holter monitor for 24 hours. This is a small, portable device that is strapped to your body. It records the electrical activity of your heart during physical activity and while at rest.

Event monitor This electrical device, which is strapped to your body, monitors your heartbeat only when you turn it on to record your symptoms. It is generally worn for one or two weeks at a time.

Blood tests Your doctor may also order blood tests to rule out thyroid disease or other blood chemistry abnormalities. Read more about blood tests.

Treatments for atrial fibrillation

Your physician will help decide what is the best approach to treat your atrial fibrillation. Your doctor will customize the treatment to your needs, based upon your risks, medical profile and how much the symptoms are interfering with your quality of life.

Most patients with atrial fibrillation will likely have to take blood thinners in order to reduce the risk of stroke. The risk of stroke depends on several other risk factors, including the presence of heart muscle weakness, having high blood pressure or diabetes, being over 75 years of age, or having had a previous stroke or a mini-stroke (TIA). Accordingly, your doctor may prescribe blood thinners such as an anti-platelet like ASA (Aspirin®) or an anticoagulant such as warfarin (Coumadin) to prevent clots from forming and travelling to the brain.

There are two general strategies for the treatment of atrial fibrillation – rhythm control and rate control. Your doctor will decide which strategy is best for you based on your symptoms and other factors.

Rhythm control These treatments attempt to prevent an irregular heartbeat by restoring and maintaining a normal, regular heartbeat. The first approach to rhythm control involves taking medications that will attempt to prevent the atrial fibrillation from occurring. Occasionally, some patients will require a controlled electric shock to the heart (called electrical cardioversion) to restore a normal rhythm. In some cases, if medications fail or are not well tolerated, your doctor may refer you to a specialist, who will decide if you are a candidate for an electrophysiologic study (see below).
Rate control Almost every patient with atrial fibrillation will be prescribed a medication that is designed to slow the heart rate during atrial fibrillation. For some, this type of medication is enough to control the symptoms of atrial fibrillation.

When taking medications of any type, it is important to follow your doctor or pharmacist’s instructions. Establish a routine for taking your pills, and keep to your daily schedule. Do not share medications with others, and do not stop taking your medication without consulting your doctor. Report any side effects to your doctor, because he or she may change the dosage or type of medication to prevent or reduce any side effects.

Electrophysiology Studies (EPS) and Catheter Ablation On rare occasions, patients with atrial fibrillation who do not respond to medications or electrical cardioversion require an EPS in order to stop atrial fibrillation from recurring. The objective of EPS testing is to locate the cause of irregular electrical impulses in the heart. Catheter ablation is then performed to destroy, through tiny burns, the electrically chaotic tissue in the heart. During EPS and catheter ablation, thin wires (or catheters) are introduced to the heart through veins in the leg and neck. Radiofrequency energy is sent through the catheters to the parts of the heart where the irregular electrical impulses are located. Ablation essentially creates scars in the heart that stabilize any electrical short circuits.

Atrial fibrillation in people under 60

If you develop atrial fibrillation and do not have any structural heart disease, this is considered idiopathic (or lone) AF. Idiopathic AF usually occurs before the age of 60. Researchers have so far identified a handful of genes that predispose families to atrial fibrillation. Once all these genes are identified, researchers may be able to develop new treatments for this condition. Those who have a genetic predisposition to Idiopathic AF may develop the disease in their 30s and 40s. It is also possible for young people who do not have AF in their family to develop the disease.

What can you do?

Healthy lifestyle changes are always a good idea. Your risk for developing many diseases can be reduced if your diet is lower in saturated and trans fats, and includes plenty of vegetables, fruit, fibre and lean protein. Quitting smoking, limiting alcohol intake and reducing stress as much as possible have been shown to improve health in numerous studies. Any lifestyle changes that lower blood pressure (such as maintaining a normal weight) are likely to reduce the chances of developing AF.

It may be possible to prevent atrial fibrillation by staying physically active. A large study of people over the age of 65 found that participating in light to moderate physical activities, particularly leisure-time activities such as gardening and walking, were associated with significantly lower AF incidence. Even if you have AF, it is important to stay physically active because doing so has a positive impact on your overall health. Consult your doctor before you become more physically active.

Visit your doctor regularly have your atrial fibrillation monitored. Do not attempt to monitor your own heart rhythm by using expensive, high-tech equipment you may find on the internet. Using such products may unnecessarily elevate stress.

If you have high blood pressure, ask your doctor how to monitor your own blood pressure at home.

Atrial fibrillation and stroke

AF increases your risk of stroke. It is estimated that up to 15% of all strokes are caused by atrial fibrillation. This risk increases with age, so that after age 60, one-third of all strokes are caused by atrial fibrillation. Also, individuals with atrial fibrillation have 3 to 5 times greater risk for ischemic stroke.

With a normal heart rhythm, the heart receives electrical signals from the brain via the sinoatrial (SA) node. The SA node sends impulses to the atria which instructs them to beat. The impulses then make their way to the lower chambers of the heart (the ventricles), which pump blood to the rest of the body.

During atrial fibrillation, the atria contract chaotically and in a disorganized manner. Because the atria don’t move blood properly, blood pools and gets stuck in the grooves of the heart. This may result in the formation of blood clots, which could get pumped to the brain and result in an ischemic stroke. An ischemic stroke is caused when blood flow to the brain is interrupted by a clot in one of the blood vessels within, or leading to, the brain. Studies show that long-term use of the blood thinner warfarin in patients with AF can reduce the risk of stroke by 70 to 80%.

Atrial fibrillation

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