Virtual Medical Centre

Atrial Fibrillation (AF)

• What is Atrial Fibrillation?
• Who gets Atrial Fibrillation?
• Predisposing Factors
• Progression
• Probable Outcomes
• How Will Atrial Fibrillation Affect Me?
• Clinical Examination
• How is Atrial Fibrillation Diagnosed?
• How is Atrial Fibrillation treated?
• Atrial Fibrillation References
• Drugs/Products Associated with Atrial Fibrillation

What is Atrial Fibrillation?

3D Animation on
Atrial Fibrillation

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Contact Andrew Walbank.

Who gets Atrial Fibrillation?

Atrial fibrillation is the most common sustained rhythm disorder of the heart. It is more common in older people, and occurs in more than 5% of the population over 65 years in Western countries. In Australia, AF affects around 2% of the general population.

Predisposing Factors

Many diseases of the heart can predispose to AF. This is particularly so for conditions that cause enlargement of the atria. In addition, there are also many non-cardiac disorders that predispose towards AF.

Common risk factors for atrial fibrillation include:

• Coronary artery disease, including heart attack
• Diseases of the heart valves, especially rheumatic heart disease
• Sick sinus syndrome 
• Hyperthyroidism
• High blood pressure
• Cardiomyopathies
• Congenital heart disease (an abnormality of the heart that is present since birth)
• Chest infection
• Pulmonary embolism
• Pericarditis
• Alcohol

In 50% of patients with paroxysmal AF and 20% of patients with persistent or permanent AF, no underlying heart disease can be found. This is known as 'lone' AF.

Progression

In AF, the atria are continuously activated by rogue electrical currents at a rate of 350-600 beats a minute. The ventricles are unable to respond to such a high rate of stimulation, and therefore only a proportion of the impulses are translated into contractions of the heart.

AF can be classified into three groups:

1. Paroxysmal AF: The patient gets repeated, short episodes of chest palpitations that resolve spontaneously. In between these episodes, the heart is normal.
2. Persistent AF: AF that does not resolve spontaneously, but resolves after treatment.
3. Permanent AF: AF that persists or recurs despite treatment. It usually occurs in patients who already have diseased hearts.

If left untreated, AF can lead to various short- and long-term problems. In patients who have pre-existing heart failure, the rapid heart rate seen in AF can lead to low blood pressure, lung congestion, angina, or worsening of the heart failure. Untreated AF also increases the risk of stroke. This is because in AF the atria become dilated and contract ineffectively, which leads to blood clots developing in the atria. These clots can subsequently dislodge and travel to the brain and other organs, causing strokes and other organ damage.

The main risk factors for developing a stroke in patients with AF are: