Atrial Fibrillation

Atrial fibrillation is a common tachycardia. It is significant, as having the condition increases the risk of stroke.


Present in:

  • 5% of the over 65’s
  • 10% of over 70’s
  • 15% of all stroke patients
    • Stroke is a major complication of AF (see below)





Lone AF – refers to cases where no cause can be found. Many cases initially labelled as lone AF have a cause discovered upon further investigation.



Often asymptomatic, but an present with:

Irregularly irregular pulse – you should do an ECG on everybody with an irregular pulse!

  • Apical pulse rate > radial pulse rate
  • 1st heart sound of variable intensity
  • Signs of LV dysfunction


AF is an irregular atrial rhythm between 300-600bpm. The AV node is unable to transmit beats as quickly as this, and thus does so intermittently, resulting in an irregular ventricular rhythm. This irregular stimulation of the ventricles reduces cardiac output by up to 20%, as well as allowing stasis of blood in the heart chambers.


ECG Findings
  • No p waves – just an irregular baseline
  • Irregular QRS – between 75-190bpm
  • Normal shape QRS – because conduction through the AV node is normal            
  • In V1 the trace resembles atrial flutter
  • Normal T waves
  • U+E’s – check for renal dysfunction
  • TFT’s – AF can be secondary to hyperthyroidism
  • Cardiac enzymes
Can be used to look for mitral valve disease, left ventricular dysfunction, left atrial enlargement.


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