Atrial Fibrillation

• Atrial fibrillation is the most commonly treated cardiac arrhythmia characterized by the irregularly irregular ventricular rhythm in the absence of a synchronous atrial depolarization (P wave)
• Prevalence increases with age and affects > 4% of the population over the age of 60
• Precipitated by alcohol, exercise, emotion
• Classification:
  • Paroxysmal AF – AF that self-terminates within 7 days of onset
  • Persistent AF – AF that does not self-terminate within 7 days of onset
  • Long-standing Persistent AF – AF persistent > 12 months
  • Permanent AF – Long-standing AF where rhythm control is no longer sought

Signs and Symptoms

• May be asymptomatic
• Classical symptoms include palpitations, weakness, fatigue, shortness of breath, dizziness and lightheadedness
• May precipitate angina, presyncope and syncope
• Signs: irregular pulses

Investigation

• ECG showing absent P waves and irregular narrow QRS ventricular rhythm

Management

• Haemodynamically unstable AF – ABCDE followed by DC cardioversion 120-150 J
• New AF (haemodynamically stable)
  • Onset < 48 hours → consider rhythm control with either
    • Electrical synchronized DC shock 120-150 J OR
    • Pharmacological: amiodarone or flecainide (contraindicated in structural heart disease)
  • Onset > 48 hours → rate control with β-blocker, calcium channel blocker e.g., verapamil or diltiazem (aim HR < 110)
    • Referral to cardiologist for consideration of rhythm control
    • Need to rule out intra-cardiac thrombus, e.g., in the left atrial appendage, before cardioversion.
  • If CHA₂DS₂-VASc ≥ 2 → thromboprophylaxis e.g. anticoagulation
• Persistent AF
  • A: Anticoagulation if CHA₂DS₂-VASc ≥ 2. May consider ORBIT or HAS-BLED scores to assess the patient’s bleeding risk
  • B: Better symptoms control
    • Rate control preferred in older patients
    • Rhythm control may be beneficial in younger patients, patients with heart failure, failure of rate control, and high-cardiovascular risk patients
  • C: Cardiovascular risk factors and comorbidities
    • Treat comorbidities e.g. hypertension, heart failure, obesity, sleep apnoea
• Choice of anticoagulation
  • Generally DOAC (e.g. apixaban, rivaroxaban or edoxaban) over vitamin K antagonist (e.g. warfarin)
  • Warfarin when
    • Mechanical heart valve
    • Severe rheumatic mitral stenosis
    • May be considered if CKD with creatinine clearance < 25 mL/min

Reference:

• UpToDate: Atrial Fibrillatin
• https://www.nice.org.uk/guidance/ng196