The Purple Book

Atrial Fibrillation (AF)

Definition & Cause

Result of chaotic atrial depolarisation from multiple areas of re-entry within the atria > irregularly irregular rhythm without discreet P waves.

Various classifications based on duration and chronicity and another (4S-AF) which describes Stroke Risk, Symptom Severity, Severity of AF burden and Substrate severity

• Ischaemic Heart disease - 50%
• Valvular disease
• Hypertension
• electrolyte disturbance – hypokalaemia, hypomagnesaemia
• Toxicity – thyrotoxicosis, alcohol
• other

Symptoms

• May present with palpitations, syncope, breathlessness

Signs

• may be hypotensive
• irregularly irregular HR
• may present with Heart Failure

Investigations

• ECG
• routine bloods: FBC, U&E's, Calcium, Mg, Thyroid Function
• ECHO - especially if high risk of structural or functional heart disease (eg HF or murmur)

Management

• Assessment of Stroke risk using CHA₂DS₂-VASc
  • anti-coagulants for stroke prevention unless <65yo and no other risk factors - assess bleeding risk using ORBIT score
    • DOAC (Apixaban, dabigatran, edoxaban and rivaroxaban) if CHA₂DS₂-VASc score ≥2 or 1 if male
    • vit K antagonist if DOAC unsuitable
  • if PHx of MI : anti-platelet therapy should be reviewed
• Rate control primarily unless - reversible cause, HF as a result of AF, new onset AF
  • β-blocker (not sotalol) or CCB (diltiazem or verapamil) unless contra-indicated or:
    • Digoxin for non-paroxysmal AF if little or no exercise
  • if poor control of symptoms (and thought to be due to poor rate control) - 2 of β-blocker, CCB or digoxin
• Rhythm control for those whose symptoms are not improved by rate control or rate control not successful:
  • 1st line: β-blocker (not sotalol)
  • 2nd line: Dronedaroneif not controlled by β-blocker and have HTN or diabetes or previous TIA/stroke/embolism/LA>50mm/>70y and do not have LV dysfunction or HF
  • Amiodarone for LV dysfunction or HF
• Cardioversion - AF>48/24
• LA ablation and pacing may be considered