Atrial Fibrillation Flashcards
What is atrial fibrillation?
Electrical activity in the atria t becomes disorganised, leading to fibrillation (random muscle twitching) of the atria and an irregularly irregular pulse
Overall effects
Irregularly irregular ventricular contractions
Tachycardia (fast heart rate)
Heart failure due to impaired filling of the ventricles during diastole
Increased risk of stroke
Pathophysiology
Normally, the sinoatrial node produces organised electrical activity that coordinates the contraction of the atria.
Atrial fibrillation occurs when this electrical activity is disorganised, causing the contraction of the atria to become uncoordinated, rapid and irregular.
Common causes
S – Sepsis
M – Mitral valve pathology (stenosis or regurgitation)
I – Ischaemic heart disease
T – Thyrotoxicosis
H – Hypertension
Alcohol and caffeine are lifestyle causes worth remembering.
Presentation
Patients are often asymptomatic, and atrial fibrillation is an incidental finding. It may be diagnosed after a stroke.
Patients may present with:
Palpitations
Shortness of breath
Dizziness or syncope (loss of consciousness)
Symptoms of associated conditions (e.g., stroke, sepsis or thyrotoxicosis)
Key examination finding
Irregularly irregular pulse.
ECG findings
Absent P waves
Narrow QRS complex tachycardia
Irregularly irregular ventricular rhythm
What is Paroxysmal Atrial Fibrillation?
Episodes of atrial fibrillation that reoccur and spontaneously resolve back to sinus rhythm.
These episodes can last between 30 seconds and 48 hours.
Principles of treatment
Rate or rhythm control
Anticoagulation to prevent strokes
Rate control in all but:
A reversible cause for their AF
New onset atrial fibrillation (within the last 48 hours)
Heart failure caused by atrial fibrillation
Symptoms despite being effectively rate controlled
Options for rate control
Beta blocker first-line (e.g., atenolol or bisoprolol)
Aim of rhythm control
Return the patient to normal sinus rhythm
What can rhythm control be done by?
Cardioversion
Long-term rhythm control using medications
What are the options for cardioversion?
Immediate cardioversion
Delayed cardioversion
When is immediate cardioversion used?
Present for less than 48 hours
Causing life-threatening haemodynamic instability
What are the options for cardioversion?
Pharmacological cardioversion
Electrical cardioversion
Pharmacological cardioversion
Flecainide
Amiodarone (the drug of choice in patients with structural heart disease)
What happens with electrical cardioversion?
shock the heart back into sinus rhythm. It involves using a cardiac defibrillator machine to deliver controlled shocks. This is usually done with sedation or general anaesthesia.
What happens in delayed cardioversion?
Used if the atrial fibrillation has been present for more than 48 hours and they are stable. Electrical cardioversion is recommended.
The patient should be anticoagulated for at least 3 weeks before delayed cardioversion.
Long term AF control
Beta blockers first-line
Dronedarone second-line for maintaining normal rhythm where patients have had successful cardioversion
Amiodarone is useful in patients with heart failure or left ventricular dysfunction
Why are DOAC better than warfarin?
No monitoring is required
No issues with time in therapeutic range (provided they have good adherence)
No major interaction problems
Equal or slightly better than warfarin at preventing strokes in atrial fibrillation
Equal or slightly lower risk of bleeding than warfarin
Most common DOAC indications
Stroke prevention in patients with atrial fibrillation
Treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE)
Prophylaxis of venous thromboembolism (DVTs and PEs) after a hip or knee replacement
CHA2DS2-VASc
C – Congestive heart failure
H – Hypertension
A2 – Age above 75 (scores 2)
D – Diabetes
S2 – Stroke or TIA previously (scores 2)
V – Vascular disease
A – Age 65 – 74
S – Sex (female)
CHA2DS2-VASc score results and actions
0 – no anticoagulation
1 – consider anticoagulation in men (women automatically score 1)
2 or more – offer anticoagulation
