ECG Features of Atrial Fibrillation

Atrial fibrillation (AF or A-fib) is an abnormal heart rhythm characterized by rapid and irregular beating. Often it starts as brief periods of abnormal beating which become longer and possibly constant over time. Most episodes have no symptoms. Occasionally there may be heart palpitations, fainting, shortness of breath, or chest pain. The disease increases the risk of heart failure, dementia, and stroke. (wikipedia)

Causes of Atrial Fibrillation

There are multiple causes of AF, including:

Ischaemic heart disease
Hypertension
Valvular heart disease (esp. mitral stenosis / regurgitation)
Acute infections
Electrolyte disturbance (hypokalaemia, hypomagnesaemia)
Thyrotoxicosis
Drugs (e.g. sympathomimetics)
Pulmonary embolus
Pericardial disease
Acid-base disturbance
Pre-excitation syndromes
Cardiomyopathies: dilated, hypertrophic.
Phaeochromocytoma

ECG Features of Atrial Fibrillation

Irregularly irregular rhythm.
No P waves.
Absence of an isoelectric baseline.
Variable ventricular rate.
QRS complexes usually < 120 ms unless pre-existing bundle branch block, accessory pathway, or rate related aberrant conduction. Fibrillatory waves may be present and can be either fine (amplitude < 0.5mm) or coarse (amplitude >0.5mm).
Fibrillatory waves may mimic P waves leading to misdiagnosis.

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