All about atrial fibrillation (AF)

Atrial fibrillation is the most common heart rhythm abnormality, affecting more than 4 out of every 100 people over the age of 65. Symptoms of AF include palpitations, irregular heartbeat, shortness of breath, dizziness, fatigue and chest pain. If you are experiencing any of these symptoms you should see a cardiologist.

What causes atrial fibrillation?

The most common causes of AF include ischaemic heart disease (previous heart attack or angina), disease of the heart valves such as mitral regurgitation, heart failure, lung disease such as chronic bronchitis, or an overactive thyroid gland (hyperthyroidism). Other acute causes include alcohol, chest infections or diarrhoea and vomiting. AF rarely occurs in younger, otherwise fit and healthy individuals following exercise, after a large meal with alcohol or during sleep - this may be due to alterations in autonomic tone (i.e. vagally-mediated AF).

Vagally-mediated atrial fibrillation

The autonomic nervous system is the specialised nervous system of the body controlling automatic bodily functions, such as control or heart rate, blood pressure and gut (peristalsis) and bladder movements. Occasionally when there is an imbalance in autonomic tone (such as that triggered following vigorous exercise, after a large meal or alcohol, or during sleep - particularly after a hectic/tiring day), AF can be induced.

Types of atrial fibrillation

AF can present intermittently and can spontaneously resolve within minutes or hours. This is termed paroxysmal AF. Another form of AF is a more persistent form, which once initiated, is sustained until the patient is cardioverted (either with electrical cardioversion or drug cardioversion). This is called persistent AF.

Treatment for atrial fibrillation

A) Stroke prevention

The most important consideration, once a diagnosis of AF is made, is the stroke risk for patients. The stroke risk should be assessed by your physician, and if this risk is high then formal anticoagulation should be recommended. Drugs that could be used include agents such as warfarin or a newer oral anticoagulant such as dabigatran, apixaban, edoxaban or rivaroxaban.

B) Rhythm and rate control of atrial fibrillation

Usually, your physician will recommend drugs initially to control AF. This may include drugs to slow heart rates down such as beta blockers or calcium channel blockers. Some patients will require rhythm control (in the case of heart arrythmia). Alternatively your doctor may recommend a direct current cardioversion (DCCV) which uses an electrical current to restart the heart in the case of heart failure, this is inserted under general anaesthetic. If there is a failure to control rhythm or rate, and patients continue to be symptomatic, a catheter ablation strategy may be appropriate. This is usually done as a key-hole procedure in a tertiary cardiac centre by an electrophysiologist.

C) Catheter ablation for atrial fibrillation

This is a procedure carried out through small incisions in both groins, to allow cardiac catheters (small electrical wires), to be inserted into the heart. These catheters are then manipulated carefully to areas of the heart (pulmonary veins) and with either burning or freezing energy, an area of scar is created in the heart to electrically isolate the pulmonary veins, with the aim to render the pulmonary veins electrically inactive, therefore preventing further recurrences of AF.