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Atrial fibrillation

Definition
  • AF: A supraventricular tachyarrhythmia characterised by uncoordinated atrial activation leading to ineffective atrial contraction.
Etiology
  • Cardiac causes: Hypertension, coronary artery disease, heart failure, valvular heart disease, myocarditis, and cardiomyopathies.
  • Non-cardiac causes: Hyperthyroidism, pulmonary embolism, alcohol (‘holiday heart syndrome’), and drugs (e.g., theophylline).
  • Idiopathic: No identifiable cause.
Pathophysiology
  • Multiple re-entrant circuits form in the atria ā†’ rapid and disorganised atrial activation ā†’ ineffective atrial contraction ā†’ irregular ventricular response.
Clinical Features
  • Symptoms: Palpitations, dyspnoea, fatigue, dizziness, or may be asymptomatic.
  • Physical Examination: Irregularly irregular pulse, variable heart sounds, may have an increased jugular venous pressure (JVP) or signs of heart failure.
Investigations
  • ECG: Absence of P-waves, irregular QRS complexes, and a variable ventricular rate.
  • Chest X-ray: To identify pulmonary oedema, cardiomegaly or other pulmonary pathology.
  • Echocardiography: Assesses atrial size, valvular pathology, and left ventricular function. May detect thrombus in the left atrial appendage.
  • Blood Tests: Thyroid function, renal function, and full blood count.
Management
  • Rate Control: Beta-blockers (e.g., bisoprolol), calcium channel blockers (e.g., diltiazem), or digoxin.
  • Rhythm Control: Amiodarone, flecainide, or sotalol. Electrical cardioversion may be used if drugs are ineffective.
  • Stroke Prevention: Anticoagulation using warfarin or direct oral anticoagulants (DOACs) like rivaroxaban or apixaban based on CHA2DS2-VASc score.
  • Ablation Therapy: Catheter ablation can target areas of the atria responsible for triggering or perpetuating AF.
Complications
  • Stroke (from thromboembolism).
  • Tachycardia-induced cardiomyopathy.
  • Heart failure.
  • Acute AF can cause haemodynamic instability.
Key Points
  • AF is the most common sustained cardiac arrhythmia.
  • Anticoagulation is pivotal in reducing the risk of AF-related stroke.
  • Management can be rate or rhythm control, tailored to the patient’s symptoms and clinical condition.

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