Atrial Fibrillation/ Flutter

Question 1

Define Atrial Fibrillation and summarise its aetiology and epidemiology

Answer 1

Definition: Characterised by rapid, chaotic and ineffective atrial electrical conduction. Often subdivided into:

• Permanent
• Persistent
• Paroxysmal

Aetiology/risk factors:
- There may be no identifiable cause
- Secondary causes lead to an abnormal atrial electrical pathway that results in AF
- Systemic causes:
   • Thyrotoxicosis
   • Hypertension
   • Pneumonia 
   • Alcohol 

- Heart causes:
   • Mitral valve disease
   • Ischaemic heart disease
   • Rheumatic heart disease
   • Cardiomyopathy 
   • Pericarditis 
   • Skin sinus syndrome 
   • Atrial myxoma 

• Lung causes
  • Bronchial carcinoma
  • PE

Epidemiology:

• Very common in the elderly
• Present in 5% of those >65 years
• May be paroxysmal

Question 2

Describe the history/presenting symptoms of Atrial Fibrillation

Answer 2

• Often asymptomatic
• Palpitations
• Syncope (if low output)
• Symptoms of the cause of AF

Question 3

What are the signs of Atrial Fibrillation upon physical examination?

Answer 3

• Irregularly irregular pulse
• Difference in apical beat and radical pulse
• Check for signs of thyroid disease and valvular disease

Question 4

What investigations are used to identify Atrial Fibrillation?

Answer 4

• ECG:
  • Uneven baseline with absent P waves
  • Irregular intervals between QRS complexes
  • Atrial flutter = saw-tooth

- Bloods:
   • Cardiac enzymes
   • TFT
   • Lipid profile 
   • U&Es, Mg2+ and Ca2+ 
        o Because there is increased of digoxin toxicity with hypokalaemia, hypomagnesaemia and hypercalcaemia

- Echocardiogram:
    May shows-
    • Mitral valve disease
    • Left atrial dilation 
    • Left ventricular dysfunction 
    • Structural abnormalities

Question 5

How is Atrial Fibrillation managed?

Answer 5

First and foremost, try to treat any reversible causes (e.g. thyrotoxicosis, chest infection)
There are TWO main components to AF management:

RHTHYM CONTROL
- If > 48 hours since onset of AF
• Anticoagulate for 3-4 weeks before attempting cardioversion
- If < 48 hours since onset of AF
• DC cardioversion (2 x 100 J, 1 x 200 J)
• Chemical cardioversion: flecainide or amiodarone

- Prophylaxis against AF
    • Sotalol
    • Amiodarone
    • Flecainide
    • Consider pill-in-the-pocket (single dose of a cardioverting drug (e.g. flecainide) for patients with paroxysmal AF) strategy for suitable patients.

RATE CONTROL
- Chronic (permanent AF)
 o Control ventricular rate with
   • Digoxin 
   • Verapamil
   • Beta-blockers

o Aim for ventricular rate aproc 90bpm

STROKE RISK STRATIFICATION
• Low risk patients can be managed with aspirin 
• High risk patients require anticoagulation with warfarin 
• Based on the CHADS-Vasc Score
• Risk factors include:
     - Previous thromboembolic event
     - Age > 75 yrs
     - Hypertension 
     - Diabetes
     - Vascular disease
     - Valvular disease
     - Heart failure
     - Impaired left ventricular function

Question 6

What are the complications of Atrial Fibrillation?

Answer 6

• Thromboembolism
  • Embolic stroke risk of 4% per year
  • Risk is increased with left atrial enlargement or left ventricular dysfunction.
• Worsening of existing heart failure

Question 7

Summarise the prognosis for patients with Atrial Fibrillation

Answer 7

Chronic AF in a diseased heart does not usually return to sinus rhythm