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Atrial Fibrillation

Background Knowledge 🧠

Definition

  • A supraventricular tachyarrhythmiaΒ characterised by uncoordinated atrial activation leading to ineffective atrial contraction.

Epidemiology

  • Atrial fibrillation is the most common cardiac arrhythmia.
  • According to the European Society of Cardiology (ESC), the prevalence of AF is between 2-4% in adults.

Pathophysiology

  • Multiple re-entrant circuits form in the atria β†’ Rapid and disorganised atrial activation β†’ Ineffective atrial contraction β†’ Irregular ventricular response.

Aetiology

  • Cardiac causes: Hypertension, coronary artery disease, heart failure, valvular heart disease, myocarditis, and cardiomyopathies.
  • Non-cardiac causes: Hyperthyroidism, pulmonary embolism, COPD, alcohol (‘holiday heart syndrome’), and drugs (e.g., theophylline).
  • Idiopathic: No identifiable cause.

Clinical Features πŸŒ‘️

Symptoms

  • Palpitations
  • Dyspnoea
  • Chest pain
  • Fatigue
  • Dizziness
  • May be asymptomatic

Signs

  • Irregularly irregular pulse
  • Variable heart sounds
  • May have an increased jugular venous pressure (JVP) or signs of heart failure.

Investigations πŸ§ͺ

Initial tests

  • 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.
  • Blood Tests: Thyroid function, renal function, and full blood count.

Diagnostic tests

  • Echocardiography: Assesses atrial size, valvular pathology, and left ventricular function. May detect thrombus in the left atrial appendage.

Management πŸ₯Ό

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.

Prognosis

  • Prognosis is dependent on the underlying cause of 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.
  • Important ECG findings include absent P-waves and irregular QRS complexes.
  • 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.

References

Gutierrez, C. and Blanchard, D.G. (2016). Diagnosis and Treatment of Atrial Fibrillation. American Family Physician, [online] 94(6), pp.442–452. Available at: https://pubmed.ncbi.nlm.nih.gov/27637120/.

Hindricks, G., Potpara, T., Dagres, N., Arbelo, E., Bax, J. J., BlomstrΓΆm-Lundqvist, C., Boriani, G., Castella, M., Dan, G.-A., Dilaveris, P. E., Fauchier, L., Filippatos, G., Kalman, J. M., La Meir, M., Lane, D. A., Lebeau, J.-P., Lettino, M., Lip, G. Y. H., Pinto, F. J., Thomas, G. N., Valgimigli, M., Van Gelder, I. C., Van Putte, B. P. and Watkins, C. L. (2021) ‘Corrigendum to: 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation developed in collaboration with the European Association for Cardio-Thoracic Surgery (EACTS): The Task Force for the diagnosis and management of atrial fibrillation of the European Society of Cardiology (ESC) Developed with the special contribution of the European Heart Rhythm Association (EHRA) of the ESC’, European heart journal, 42(40), pp. 4194-4194.

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Treatment options for atrial fibrillation include which of the following?

This is an intravenous atrioventricular node-blocking agent used for supraventricular tachycardia.

This is a class 1c antiarrhythmic

This is an intravenous agent used in ventricular arrhythmias.

This is a treatment for ventricular arrhythmias.

This is an intravenous anaesthetic agent.


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