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Atrial fibrillation is a supraventricular tachyarrhythmia characterised by ineffective, chaotic, irregular and rapid (300 to 600 beats per minute) atrial activity resulting in the deterioration of atrial mechanical function (1).
AF is the most common sustained cardiac arrhythmia seen in the general population (2)
- in majority it is thought to be caused by rapidly firing cells located at the junction of the pulmonary veins with the left atrial musculature (3)
- these rapidly firing impulses are responsible for disorganized atrial depolarization and ineffective atrial contractions
- in turn, it results in an irregular ventricular rate because the impulses from the atria approach the atrioventricular node from varying angles and at varying intervals.
Atrial fibrillation is often seen in the elderly and generally is asymptomatic.
If atrial fibrillation occurs when there is a large atrium, for example in mitral
stenosis, then this is a predisposing factor to the development of thromboembolism.
Structural, functional, and electrophysiological
changes resulting from a complex interplay of risk
factors are thought to be responsible for the initiation,
progression, and maintenance of atrial fibrillation (5):
- in many patients, these changes may include:
- diastolic dysfunction
- left atrial fibrosis
- left atrial
- autonomic dysfunction
- in some patients with atrial fibrillation especially in young patients,
no identifiable risk factors may exist, suggesting a
possible genetic predisposition
- atrial fibrillation can by itself sustain and further promote
atrial, ventricular, and systemic structural and
- use the CHA2DS2-VASc stroke risk score to assess stroke risk in people with
any of the following (4):
- symptomatic or asymptomatic paroxysmal, persistent or permanent
- atrial flutter
- a continuing risk of arrhythmia recurrence after cardioversion back
to sinus rhythm
Anticoagulation in chronic atrial fibrillation (4)
- anticoagulation may be with apixaban, dabigatran etexilate, rivaroxaban
or a vitamin K antagonist
- consider anticoagulation for men with a CHA2DS2-VASc score of 1. Take
the bleeding risk into account
- offer anticoagulation to people with a CHA2DS2-VASc score of 2 or above,
taking bleeding risk into account
- do not offer stroke prevention therapy to people aged under 65 years
with atrial fibrillation and no risk factors other than their sex (that
is, very low risk of stroke equating to a CHA2DS2-VASc score of 0 for
men or 1 for women)
Excess mortality (5):
- do not offer aspirin monotherapy solely for stroke prevention to people
with atrial fibrillation (4)
Classification of AF (5):
- atrial fibrillation is classified as "paroxysmal"
if episodes terminate spontaneously or after
targeted intervention within seven days, whereas
atrial fibrillation lasting more than seven days
without termination is considered "persistent"
and often requires electrical or pharmacological cardioversion for termination
- atrial fibrillation
that persists continuously for longer than a year is
termed "longstanding persistent atrial fibrillation"
- when the patient and clinician decide not to
pursue anyany attempt to restore normal rhythm, atrial
fibrillation is considered "permanent"
Last edited 04/2021 and last reviewed 04/2021