What is atrial fibrillation and atrial flutter?

Atrial fibrillation is one of the most common heart rhythm disturbances during which the upper chambers (the atria) beat in a fast and chaotic pattern. In atrial fibrillation, the electrical activity of the atria becomes uncoordinated. The atria beat so rapidly — as fast as 300 to 400 beats a minute — that they quiver or “fibrillate”. Fortunately, only a portion of these atrial impulses reaches the lower or pumping chambers of the heart (ventricles). Still, extra impulses often get through and this may accelerate your pulse up to 150 beats a minute or more.

Atrial flutter is another heart rhythm disturbance similar to atrial fibrillation. The upper heart chambers (the atria) also beat more rapidly than normal (or “flutter”) up to 300 beats a minute, but tend to be in a more regular and coordinated fashion. It can still cause the ventricles to beat rapidly and generally is associated with similar sorts of symptoms as atrial fibrillation. It is also treated in a similar manner to atrial fibrillation.

Both atrial fibrillation and atrial flutter can occur intermittently, lasting for minutes up to days and even weeks at a time. There are also many people who have these heart rhythm disturbances permanently (chronic atrial fibrillation/flutter).

Atrial fibrillation and atrial flutter are seldom life-threatening arrhythmias, but may be a sign of significant underlying heart problems. In addition, they can be the cause of more serious conditions such as stroke. Therefore, it is important that people with these rhythm disturbances are thoroughly assessed by a doctor, undergo appropriate investigations and receive treatment tailored to their individual situation.

What may I feel if I have one of these rhythm disturbances?

There may be no symptoms with atrial fibrillation or flutter. In fact, your doctor might detect them before you do during a routine examination. But often, abnormal heart rhythms cause noticeable symptoms and signs, which may include:

• fluttering in your chest
• racing heartbeat
• chest pain
• shortness of breath
• light headedness
• dizziness
• fainting

What causes atrial fibrillation and atrial flutter?

Atrial fibrillation and atrial flutter are associated with a number of medical conditions – some heart-related and others not necessarily to do with heart abnormalities. In a significant number of people, no cause for the rhythm disturbance is ever found. It is also more common in the elderly, with up to 12% of the population over 75 years in chronic atrial fibrillation.

Some of the heart conditions that may lead to the development of atrial fibrillation and atrial flutter include:

• Coronary artery disease with narrowing of the coronary arteries leading to reduced blood and oxygen to the heart muscle and eventual heart muscle damage. The abnormal heart muscle may be prone to heart rhythm problems
  damage to heart muscle from virus infections and other causes
• Valvular heart disease where leaking or narrowing of your heart valves can lead to stretching and thickening of the muscle and an increased risk of developing arrhythmia
• High blood pressure that can put extra strain on the heart and chamber walls resulting in an increased incidence of rhythm disturbances
• Conditions unrelated to underlying heart disease that may result in atrial fibrillation include thyroid problems, sleep deprivation and other major physical stresses, alcohol and acute illnesses such as pneumonia or major surgery, significant lung disorders such as emphysema and obstructive sleep apnoea
• Some drugs – especially those with stimulant actions

What can happen to me if I have atrial fibrillation or atrial flutter?

Stroke is the most serious and feared consequence of atrial fibrillation or atrial flutter. When your atrial chambers fibrillate, they are unable to pump blood effectively. Stagnant blood in the atria can congeal to form blood clots. If a clot breaks loose, it can travel to and block a brain artery, causing a stroke. This increased risk of stroke is mainly seen in people over 65 years, in those with high blood pressure, diabetes, previous stroke or weakened heart muscle. If you fall into one of these groups you may need to take blood-thinning drugs (anticoagulants), such as warfarin to reduce the risk of blood clots.

Congestive heart failure can result if your heart is pumping ineffectively for a prolonged period at a rapid rate due to the rhythm problem. Controlling the heart rate with drugs or other methods usually results in improved heart function.

How are these rhythm disturbances diagnosed?

Tests will need to be performed to confirm the diagnosis of atrial fibrillation or atrial flutter and look for any possible underlying causes. These may include -:

• Electrocardiogram (ECG): An ECG can positively confirm the diagnosis if the rhythm disturbance is actually occurring at the time of the recording. This test may not be helpful if the arrhythmia is intermittent.
• 24-hour heart (Holter) monitor: This portable ECG device can be worn for a day to record your heart’s activity as you go about your routine. This may pick up intermittent arrhythmias.
• ECG 7-day event monitor: This monitor is similar in concept to a Holter monitor, but can be applied for up to 1 week at a time. It therefore increases the chance of capturing an intermittent rhythm problem on an ECG recording.
• Echocardiogram: An ultrasound test that looks specifically at the heart, its muscle, chambers and valves. It is an accurate test to determine whether there is any underlying heart problem. However, it does not show if there are any blockages or narrowings in the coronary arteries.
• Stress test: This may be performed to bring on a rhythm disturbance if there is a particular association with exercise. It may also be used as a screening test for the presence of coronary artery disease.
• Thyroid function tests: A simple blood test to measure the activity of the thyroid gland.

Can these rhythm disturbances be treated?

There are several different types of treatment for atrial fibrillation and atrial flutter. Various combinations, including drugs and other strategies such as electrical shock cardioversion or pacemaker insertion are used and depend on the individual and his or her own particular circumstances. Treatment needs to be tailored specifically to your needs. However, the general principles of treatment are:

• Control the heart rate. Atrial fibrillation and atrial flutter are often associated with a rapid heart rate. The general aim of treatment is to keep the pulse rate between 50 – 100 beats per minute and this is achieved with the use of medications. Medicines frequently used include digoxin (Lanoxin), beta blockers such as metoprolol (Betaloc, Metohexal), and atenolol (Tenormin, Tensig, Noten), calcium channel blockers such as verapamil (Isoptin, Veracaps) and diltiazem (Cardizem). More powerful anti-arrhythmic medications are sometimes used such as sotalol (Sotacor) and amiodarone (Cordarone X, Aratac). Occasionally, the pulse may vary between being too fast or too slow, or the medications themselves result in excessively slow heart rates. In these cases, a pacemaker may be also be required.
• Prevent stroke. For people at increased risk of stroke, (>5% chance per year) an anticoagulant medicine is usually recommended. Warfarin has been prescribed for many years, but can be inconvenient to use. There are newer agents now that are as effective as warfarin but easier to use and don’t require regular blood testing to monitor their effects. These include dabigateran (Pradaxa), rivaroxaban (Xarelto) and apixaban (Eliquis). If you need an anticoagulant, your doctor will discuss the various choices with you.
• Re-establish normal heart rhythm. In some but not all cases, it may be appropriate to attempt to reset the heart rhythm back to normal or “sinus” rhythm. This may be achieved with anti-arrhythmic medicines such as sotalol and amiodarone. An electrical shock cardioversion may also be required. This is done under general anaesthesia, with electrical paddles placed on the chest and a momentary electric shock delivered to the heart to “reset” the rhythm. Anti-arrhythmic drugs are still generally required after cardioversion, and anticoagulants are also needed for at least 4 weeks afterwards.
• Ablation procedure: In appropriate cases, atrial fibrillation and atrial flutter can be treated with ablation whereby small burns or lesions are made on the inside of the heart with special catheters. This has the effect of interrupting the electrical circuits or triggers for the arrhythmia. The procedure is similar to an angiogram in that catheters are placed into the heart through a vein in the groin. It may be done under general anaesthesia and involves at least an overnight stay in hospital. While effective, this technique is not for everyone and your doctor can provide more information regarding your potential suitability for this treatment.

Is there anything I can do with my diet and lifestyle that can help?

Your doctor may advise that in addition to other treatments, you may need to make lifestyle changes that will keep your heart as healthy as possible. These may include cutting back on caffeine and alcohol, increasing physical activity and quitting smoking. You might also be asked to find ways to reduce the amount of stress in your life.