Medically Fit For Exams
Medically Fit For Exams

Atrial Fibrillation

Definition

  • Poorly synchronised atrial contraction/depolarisation, resulting in irregular signals being transmitted by the AVN node, and giving an irregularly irregular pulse

 

Risk factors

  • Age
  • Hypertension
  • Coronary artery disease
  • Heart failure
  • Valvular heart disease
  • Diabetes
  • Obesity
  • Chronic kidney disease
  • Post-surgical

 

Differential diagnoses

  • Heart block
  • Atrial flutter
  • Anaemia
  • Wolff-Parkinson-White syndrome
  • Ventricular tachycardia

 

Epidemiology

  • Most common sustained cardiac arrhythmia
  • 3% prevalence in adults over 20
  • Prevalence roughly doubles with each 10 years of age
    • 0.5% at 50-59
    • 9% at 80-90
  • More common in men, especially over the age of 60

 

Aetiology

  • Varied causes, although around 11% are idiopathic (Lone AF)
  • Most common causes are:
    • Coronary artery disease
    • Hypertension
    • Valvular heart disease
    • Hyperthyroidism
  • Less common cardiac causes include:
    • Heart failure
    • Pericarditis
    • Myocarditis
    • Atrial septal defect
  • Non-cardiac causes include:
    • Drug induced (thyroxine, beta agonists)
    • Infection
    • Electrolyte depletion
    • PE
    • Lung cancer
    • Diabetes
  • Lifestyle factors include:
    • Caffeine intake
    • Alcohol intake

 

Clinical features

  • Irregularly irregular pulse
  • May also have tachycardia (fast AF)
  • Breathlessness/fatigue
  • Syncope/dizziness
  • Palpitations
  • Chest pain (cardiac)
  • Stroke/TIA (AF is a contributing factor – these may be first presentation of AF)
  • May be paroxysmal (reverses with 48 hours), recurrent, prolonged or permanent

 

Pathophysiology

  • Pathogenesis isn’t well understood, especially in patients with otherwise relatively healthy hearts
  • Familial AF is rare, has recognised genetic basis
  • Trigger factors lead to rapid ectopic firing in the muscular sleeves of the pulmonary veins
  • Abnormal atrial tissue allows the generated arrhythmia to perpetuate

 

Investigations

  • ECG – no P waves, irregular QRS
    • May need 24h ambulatory if paroxysmal AF
  • Bloods
    • Thyroid function
    • FBC (anaemia)
    • BNP (heart failure)
    • U&Es (electrolyte, renal dysfunction)
  • Echocardiogram, can help predict stroke risk

 

Management

  • Thromboprophylaxis to prevent stroke
    • Warfarin
    • Apixoban
    • Rivaroxaban
    • Edoxaban
    • Dabigatran
  • Rate control, if tachycardia
    • Beta blockers
    • Digoxin
    • Calcium channel blocker, eg diltiazem
  • Rhythm control
    • Electrical cardioversion
    • Left atrial ablation
    • Pacing
    • Amiodarone, dronedarone
    • Beta blockers

 

Prognosis

  • Double the risk of mortality
  • 5x risk of stroke
  • Prognosis depends on comorbidities and age

Get social with us.

Print Print | Sitemap
© medicallyfitforexams.co.uk