Atrial Fibrillation Flashcards
What is atrial fibrillation?
Condition where the electrical activity in the atria become disorganised > fibrillation + irregularly irregular pulse
What is fibrillation?
Random muscle twitching
Overall effects of AF
- tachycardia
- irregular irregular pulse
- heart failure pEF
- increased stroke risk
AF on an ECG
- irregularly irregular
- narrow QRS tachycardia
- absent P waves
- irregular gaps between QRS complexes
Why does AF increase risk of stroke?
- uncoordinated atria activity leads to stasis of blood > blood stagnates in atria
- thrombus formation
- this can travel to the brain + block a cerebral artery > ischaemic stroke
Common causes of AF
SMITH
- Sepsis
- Mitral stenosis or regurgitation
- IHD
- Thyrotoxicosis (hyper)
- Hypertension
- high alcohol + caffeine intake
Presentation of AF
- often asymptomatic
- irregularly irregular pulse
- palpitations
- SOB
- dizziness or syncope
- symptoms of assocaited symptoms e.g. hyperthyroidism
What arrhythmias can cause irregularly irregular pulse?
AF
Ventricular ectopics
Investigations of AF
- manual pulse
- ECG
- echocardiogram
- 24 hour cardiac monitoring in paroxysmal AF
What is paroxysmal AF?
Episodes of AF that occur intermittently
Investigations of paroxysmal AF
24 ambulatory ECG (first line)
Cardiac event recorder over 1-2 weeks
What is valvular AF?
AF with significant mitral stenosis or mechanical heart valve
When should an echo be done?
- if suspected structual heart disease e.g HF or valvular heart disease
- where a rhythm control strategy e.g. cardio version is being considered
- baseline echo to inform long term Tx
Principles of AF management
- anticoagulation to prevent stroke
- rate (first line) or rhythm control
Most common combination of treatment for AF
beta blocker for rate control
DOAC for anticoagulation
Aim of rate control in AF
- Heart rate <100 bpm
- Extend the time during diastole for ventricles to fill
Options for rate control in AF
- Beta blocker e.g. bisoprolol - first line
- CCB e.g, verapamil or Diltiazem
- digoxin - in sedentary people + risk of toxicity
Is rate or rhythm control first line in AF?
Rate control is first line
Normally rate control is first line in AF, when is it not?
Therefore, rhythm control is offered
- reversible cause of AF
- new onset of AF (within 48 hours)
- heart failure caused by AF
- symptoms despite being effectively rate controlled
Aim of rhythm control in AF
Return patient to normal sinus rhythm
Options of rhythm control in AF
- cardioversion: immediate or delayed
- long term managment with meds
When is immedaite cardioversion used for rhythm control in AF?
- AF present for <48 hours
- causing life threatening Haemodynamic instability
Options for immediate cardioversion
- Pharmacological: flecainide or amiodarone
- electrical: using cardiac defibrillator
What drugs are used for pharmacological cardioversion?
flecanide
amiodarone (if structural heart disease)
When is delayed cardioversion used for rhythm control in AF?
AF present for >48 hours + pt stable
Options for delayed cardioversion in rhythm control of AF
- transoesophageal echocardiogram guided cardioversion - first line
- amiodarone after
Drug options for long term rhythm control in AF
- beta blockers: first line
- dronedarone: second line to maintain normal rhythm
- amiodarone: pts with HF or LV dysfunction
Management of paroxysmal AF
- ‘pill in pocket’ approach
- take flecainide when they feel symptoms
- CHADSVASC score + anticoagulation if needed
What can be used if drug treatment of rate + rhythm control of AF is not tolerated?
Ablation:
- left atria ablation
- AV node ablation + pacemaker
Outline anticoagulation in AF
- CHA2D2SVASC score to predict risk of stroke
- DOAC first line investigations
- warfain second line
What is the CHA2DS2VASC score?
- tool to assess whether a patient withi AF should start anticoagulation based of risk of stroke
- Congestive cardiac failure
- Hypertension
- A2ge >75 (scores 2)
- Diabetes
- S2troke or TIA before (scores 2)
- Vascular disease
- Age 65-74
-
Sex female
.
Results of CHA2DS2VASC score
- 0 - no anticoagulation needed
- 1 - consider
- 2+ - offer anticoagulation
Mechanism of action of DOACs + examples
- direct factor Xa inhibitors: apixaban, edoxaban, rivaoxaban
- direct thrombin inhibitor: dabigatran
Reversal agents of DOACs
- andexanet alfa - apixaban + rivaroxaban
- idarucizumab - dabigatran
Mechanims of action of warfarin
Vitamin K antagonists
Prevents function of clotting factors II, VII, IX + X
Prolonged PT time
What clotting factors does warfarin inhibit?
II
VII
IX
X
Outline INR
- international normalised ratio
- calculates patietns PT time compared to average healthy adult
- INR 1 - normal PT time compared
- INR 2 - PT twice as long as normal healthy adult
Target INR for AF
2-3
Reversal agent of warfarin
Vitamin K
What scores can be used to assess risk of major bleeding in pts with AF taking anticoagulation?
ORBIT
HAS-BLED
Outline ORBIT score
- assesses risk of major bleeding in AF pts on anticoagulation
- Older age >75
- Renal impairment eGFR <60
- Bleeding previously
- Iron (low Hb or haematocrit)
- Taking antiplatelet meds
Outline HAS-BLED score
assesses risk of major bleeding
What is left atrial appendage occulsion?
- Option for patients with contraindications to anticoagulation + high stroke risk
- left atrial appendage is most common site for thrombus to form
- plug placed in LAA to prevent blood from entering > reducing thrombus risk
What class of drug is amiodarone?
Group III anti-arrhythmic
Blocks K+ channels
Mechanism of action of amiodarone
- blocks K+ channel
- prolongs repolarisation by inhibiting K+ efflux
- prolongs AP
Side effects of amiodarone
- lung fibrosis
- hepatotoxic
- optic neuritis
- thyroid toxicity
- peripheral neuropathy
Contraindications of amiodarone
Heart block
Active thyroid disease
How can you differentiate between an irregularly irregular pulse due to AF and ventricular ectopics?
- Ventricular ectopics disappear when Hr increases above a certain threshold
- Increased regular HR during exercise suggests ventricular ectopics
