Atrial Fibrillation (AF)

Exam Cram

• Atria contracts irregularly irregular

• Presentation: palpitations, (pre)syncope

• ECG: QRS irregularly irregular, absent p waves, variable rate

• Acute management: 

  • • Cardiovert now-  DC shock, amiodarone, flecainide

    • Anti-coagulate and return for cardioversion

    • Rate control: betablocker/ digoxin

• Long Term Management

  • • Anticoagulation: DOAC if CHADVASC > 1 & outweighs HAS-BLED bleeding risk

    • Rate control: betablocker or digoxin

    • Rhythm control: flecainide, amiodarone; cardiac ablation

Outline

Background

Assessment

History

Examination

Investigations

Diagnosis 

Criteria:

Differentials

Management

Acute Management

Summary: if unstable, requires an emergency shock & transfer to resus. If stable and symptoms started < 48hrs, can cardiovert electrically or chemically. If symptoms start > 48hrs, requires elective outpatient cardioversion under anticoagulation and after a normal ECHO. 

1. If unstable (signs in next section)

   • DC Cardioversion

   • Transfer to resus

2. If presenting < 48 hrs & stable: cardiovert

   • Electrical: DC Cardioversion

   • Chemical: 

     1. Flecainide

     2. Amiodarone

3. Presenting > 48 hrs: elective cardioversion

   • Start anticoagulation, usually DOAC

   • Return for elective elective or chemical cardioversion

   • Requires ECHO to rule out left venticular thrombus

Med Reg Notes

Signs of unstable AF

• Shock: MAP < 65

• Myocardial ischaemia (i.e. chest pain)- rate related TWI and mild troponitis unconcerning

• Syncope: sign of cerebral hypoperfusion

• Cardiac failure: e.g. acute pulmonary oedema

Rate control: flecainide vs amiodarone vs digoxin

Flecainide

• Contraindicated in those with structural heart defects, e.g. previous myocardial infarctions

• Known as 'pill in the pocket', can be used for paroxysmal AF if patients can self detect and self administer 

Amiodarone

• If given with digoxin, reduce dose of digoxin to avoid toxicity

• Used in unwell patients with AF

• Significant side effect burden

  • • Hypo/hyperthyroidism, pulmonary fibrosis, liver fibrosis

Digoxin

• Used for patients with atrial fibrillation + acute heart failure

Left ventricular thrombus

Cardioversion cannot be done in patients who have been in AF for > 48hrs due to the risk of left ventricular thrombus forming. This could embolise at the point of cardioversion, causing an emobolic stroke. 

Complications

Stroke

• Morbidity from atrial fibrillation is greater from the risk of stroke than congestive heart disease.

• Approximately the annual risk of stroke in atrial fibrillation 7% and this is reduced to 2% with a DOAC. 

Congestive Heart Failure

• Atrial fibrillation is associated with an increased rate of developing CHF

Atrial Flutter

Notes

• ECG: saw tooth'd 

• Rate usually 2:1, 3:1 or 4:1, reflects the ratio of atrial contractions to ventricular

• Rate divisible by 300, e.g 2:1 rate is 150

• Management the same as atrial fibrillation

  • Requires anticoagulation

  • Rhythm vs rate control

Page written in 2024.