AF (1*) Flashcards
What is its pathophysiology?
What are the causes?
What are its differentials?
What are the complications?
➊ Uncoordinated, irregular atrial contractions, which leads to irregular ventricular contractions
➋ SMITH:
• Sepsis
• Mitral valve stenosis/regurgitation - If due to this, AF is classed as Valvular AF (rest is classed as non-valvular AF)
• IHD
• Thyrotoxicosis
• HTN
N.B. Can also be due to alcohol consumption, which can lead to myocarditis and damage to the heart’s electrical conduction system
➌ • Atrial flutter (saw-tooth pattern on ECG)
• Ventricular ectopics
• Atrial extrasystoles
• Sinus tachycardia
➍ Either due to uncontrolled heart rate, embolism, or anticoagulation:
• HF (poor diastolic ventricular filling)
• Systemic emboli - Ischaemic Stroke, Mesenteric ischaemia, Acute limb ischaemia
• Bleeding - GI, Intracranial
How is it usually diagnosed in elderly pts?
How can it present?
What may be found O/E?
What’s the other differential for an irregularly irregular pulse?
→ How can this be differentiated from AF?
➊ Asymptomatic, therefore diagnosed at routine checks
➋ • Palpitations
• SOB
• Dizziness
• Syncope
• Features suggestive of the underlying cause
➌ • Irregularly irregular pulse
• Features suggestive of the underlying cause
➍ • Ventricular ectopics
→ ECG - In VE, it will normalise when HR is raised over a threshold, whereas it will stay abnormal in AF
Investigations:
What will be seen on an ECG?
What other investigations should be done?
➊ · Irregularly irregular ventricular contractions
· Absent P waves
N.B. AF tends to show a fibrillating baseline w/no discernible p waves. This can resemble flutter, but atrial flutter would be more widespread over multiple leads.
➋ · Bloods - FBC (anaemia), TFT (hyperthyroidism), U&E
· Echo - look for structural defects
· CXR - look for lung problems
Management:
What is usually 1st line?
→ Which pts doesn’t this include?
→ What are the drug options here?
What is the other option?
→ How is this achieved?
What is Fast AF defined as?
→ How is this managed?
What can be done for pts with uncontrolled symptoms and an identifiable locus on EP studies?
➊ Rate control
→ Those whose AF has a reversible cause, or have HF primarily caused by the AF
→ B-blockers (1st line), Non-DHP CCB, Digoxin
‣ B-blockers avoided in COPD, Asthma, Postural hypotension
‣ CCB avoided in HF due to negative inotropic effect
‣ Digoxin avoided in young pts due to risk of cardiac mortality (typically better for older, bedbound pts)
➋ Rhythm control
→ * Electrical cardioversion - If onset is acute (<48 hrs), pt can be DC cardioverted under GA. If onset >48 hrs/unknown, pt has to be anticoagulated for 3 wks prior to being DC cardioverted.
* Pharmacological cardioversion - Flecanide (1st line), Amiodarone
‣ Flecanide avoided in older pts with structural heart abnormalities, so is preferred in younger pts
N.B. Anticoagulation is needed for 3 wks if the pt has been in AF for > 48 hrs because, if they’re cardioverted, there’s a risk of throwing off a clot and causing more damage. The DOAC will help reduce the risk of this prior to cardioversion.
N.B. Flecainide works by blocking rapid Na influx, therefore preventing the production of an action potential and slowing down the heart.
➌ > 100bpm
→ * A-E approach to check for any haemodynamic instability
* If pt is unstable, then they need immediate DC Cardioversion
➍ Ablation (done in the left atrium)
Anticoagulation:
Why is this important long-term?
Which score is used to assess the risk of stroke?
→ What do the results indicate?
Which score is used to assess the risk of bleeding if pt is given anticoagulation?
What is the 1st line drug option?
What is the 2nd line drug option?
➊ To reduce the risk of cardioembolic stroke
➋ CHA2DS2-VASc
→ • 0 - no anticoagulation
• 1+ (M), 2+ (F) - give anticoagulation
➌ ORBIT
➍ DOAC - e.g. Apixaban, Rivaroxaban, Dabigatran
• Doesn’t require monitoring
• Has a half-life of 12 hrs, therefore if a dose is missed, the pt won’t be covered
➎ Warfarin
• Requires INR monitoring
• Has a half-life of 40 hrs, therefore its effect lasts days
• The only oral drug licensed for valvular AF
