About Atrial Fibrillation (AF)
Atrial fibrillation (AF) is an abnormal heart rhythm (arrhythmia) where rapid and irregular rhythm disturbances of the upper chambers of the heart (atria) override the normal heart rhythm. The normal heart beat for an adult is between 60 and 100 beats per minute (bpm). When the heart is in AF, the atria can beat in excess of 300 bpm. The lower chambers (ventricles) try to keep up with the upper chambers, but are irregular and often in the range of 100-200 bpm. The rate in the lower chambers is often slowed when patients are on medications, but the upper chambers remain rapid.
AF itself is not a life-threatening heart rhythm, but it can be extremely annoying and sometimes dangerous. Blood is not pumped through the heart normally during AF and this may lead to an increased risk of blood clots and strokes. Effective treatment for AF returns the heart to a normal rhythm or controls the heart rate, and reduces the risk of blood clots and strokes.
AF is the most common abnormal heart rhythm. 8 out of every 100 people over the age of 65 are diagnosed with AF.
Symptoms of AF
The symptoms of AF vary greatly for each person. AF can be free of any symptoms in some people, but can cause uncomfortable symptoms in other people.
Possible symptoms include:
- Palpitations – An awareness of the heart beating differently to normal.
- Irregular Pulse – A pulse that is faster than normal, or varying between fast and slow.
- Shortness of Breath – Especially on exertion.
- Fatigue or Tiredness – Usually during the episodes of AF, although medications used for AF can also fatigue people even when they are in normal rhythm. This can lead to limitations with exercise and activities.
- Chest Discomfort or Pain – Due to the heart not beating as efficiently.
- Dizziness or Feeling Light-headed – Especially during more rapid episodes of AF.
- Syncope – Passing out or fainting.
- Urinary Frequently – Needing to pass urine more frequently due to a hormone released by the heart when it is in AF.
A wide range of risk factors may contribute to the AF such as:
- Older than 60 years of age.
- High blood pressure.
- Coronary heart disease.
- Congestive heart failure.
- Heart valve disease.
- Prior open heart surgery.
- Thyroid disease.
- Chronic lung disease.
- Obstructive sleep apnoea.
- Serious illness, infection or non-cardiac surgery.
- Excessive alcohol consumption.
- Inherited (genetic) AF.
Sometimes, there is no obvious cause for the AF to develop. It is more common for younger people to have no evidence of any other heart disease on testing, such as an echocardiogram or exercise stress test. This is often called “Lone AF”. AF increases in frequency with advancing age.
A careful examination and thorough review of medical history by a cardiologist are crucial to the diagnosis of AF. The diagnosis is often suspected during the clinical examination, but an electrocardiogram (ECG) confirms the diagnosis. You cardiologist might need to monitor your heart rhythm over a period of time with a Holter Monitor or Event Loop Recorder.
Investigations used to assess people with AF include:
- 12 lead Electrocardiograph (ECG).
- Holter Monitor.
- Implantable Event Loop Recorder.
- Transoesophageal Echocardiography.
- Exercise Stress Test.
- CT Coronary Angiogram.
- Cardiac Electrophysiology.
- Cardiac MRI.
- Cardiac Electrophysiology Study (EPS).
Different Patterns of AF
Three different types of AF are recognised.
Episodes come and go on their own. The AF may last for seconds, minutes, hours or days before the heart returns to its normal rhythm. As the heart goes in and out of AF, the pulse rate may change from slow to fast and back again. People with this type of AF are often more symptomatic.
Episodes come and usually last until the person is put back into normal rhythm, either with medications or by an electrical shock (cardioversion, direct current counter shock (DCCS)). It is unknown how long the heart will then stay in rhythm. Certain medications may reduce the recurrence of AF.
Permanent (or Long-standing Persistent)
The heart stays in AF despite efforts to convert it back to normal rhythm with medications, cardioversion or ablation procedures.
The Main Goals of Treatment
Restore the Heart’s Normal Rhythm
If AF is not treated, it can eventually weaken the heart muscle and cause permanent damage. Restoring the heart’s regular rhythm can relieve the symptoms of AF and prevent dangerous blood clots from forming.
Control the Heart’s Rate During AF
Controlling rapid heart rates allows the heart to pump oxygen-rich blood efficiently, relieves some or all symptoms and protects against a weakening of the heart muscle. Controlling the rapid heart rates, however, does not address the underlying arrhythmia or the risk of clots and strokes.
Treat Any Underlying Cause of AF
To reduce the frequency of the AF and the likelyhodd that it will progress over time. Treatment of blood pressure, weight and sleep apnoea are essential.
A number of treatment options are available, including:
AF can be treated with a variety of medications, which include:
- Medication intended to restore the heart’s normal rhythm and try to prevent the recurrence of AF.
- Medication to help control the pulse (ventricular) rate.
- Blood thinning medication (anticoagulants).
Blood Thining Medication
To reduce the risk of clots and strokes, blood thinning medications (anticoagulants) such as Warfarin (Coumadin or Marevan), Dabigatran (Pradaxa), Rivaroxaban (Xarelto) and Apixaban (Eliquis) are often used.
All of the medications used to treat AF may have side effects and an adjustment of the dosage, or change to another medication, is often necessary. Medications may reduce the frequency of, or even eliminate episodes of AF, but AF will resur in many people. Medications do not cure AF and if a patient who is responding well to a medication stops taking it, the AF will return.
When medication fails to restore the heart's normal rhythm, an electric shock can be delivered to the chest wall to restore a normal rhythm. This may sound scary, but it is a simple day procedure. Follow the link to find out more about Electrical Cardioversion.
While medications are often the preferred treatment, sometimes implanted pacemaker devices are used to treat people with AF, usually in those whose heart beat is slower than it should be. Follow the link to find out more about Pacemaker Therapy.
These devices are rarely used to treat AF, unless there are other heart problems identified during the assessment of AF. Follow the link to find out more about ICDs.