Cardiology - Atrial Fibrillation Flashcards
Why can AF increase the risk of thrombus formation?
Uncoordinated atrial activity causing blood to stagnate in the atria
5x higher risk in AF for a stroke
What lifestyle factors can cause AF?
Alcohol
Caffeine
What are the most common causes of AF?
SMITH
Sepsis
Mitral valve pathology
Ischaemic heart disease
Thyrotoxicosis
Hypertension
What is the key examination finding in AF?
Irregularly irregular pulse
May also be ventricular ectopics
What happens to ventricular ectopics during exercise?
Ventricular ectopics disappear when heart rate is high enough and heart rate becomes normal
What are the ECG findings for AF?
Absent P waves
Narrow QRS complex tachycardia
Irregularly irregular
What is paroxysmal atrial fibrillation?
Episodes of AF that reoccur and spontaneously resolve back to sinus rhythm
Episodes last between 30 seconds and 48 hours
What investigations are used for suspected paroxysmal AF?
24 hour ambulatory ECG (Holter monitor)
Cardiac event recorder (lasts 1-2 weeks)
What is valvular atrial fibrillation?
AF with significant mitral stenosis or a mechanical heart valve
Assumption is that AF has been caused by valvular issue
How is AF managed?
Rate or rhythm control
Anticoagulation to prevent strokes
How do ventricles fill in AF?
Suction and gravity as atrial contractions are not coordinated
So higher heart rate less time for filling, reducing CO
Rate control to bring heart rate down to increase filling
When should patients with AF not be given a rate control as first line?
A reversible cause for AF
New onset within 48 hours
Heart failure caused by AF
Symptoms despite being controlled well
What options are used for rate control in AF?
Beta blocker (atenolol or bisoprolol)
Calcium-channel blocker (diltiazem or verapamil)
Digoxin
When is rhythm controlled offered to AF patients?
Reversible cause
New onset within 48 hours
Heart failure due to AF
Symptoms despite being controlled well
What options are used for rhythm control?
Cardioversion
Long-term rhythm control with medications
When is immediate vs delayed cardioversion used?
Immediate
- Present for less than 48 hours
- Causes life-threatening haemodynamic instability
Delayed
- AF present for more than 48 hours and stable
- Patient should be anticoagulated for at least 3 weeks
- If patient has developed a clot in the atria reverting to sinus can mobilise the clot
What is used for immediate cardioversion?
Flecainide
Amiodarone (drug of choice with structural heart disease)
Electrical cardioversion
What is used for long-term rhythm control whilst waiting for cardioversion?
Beta blockers- first line
Dronedarone- second line, maintaining normal rhythm where patients have had successful cardioversion
Amiodarone- HF or LV dysfunction
How is paroxysmal AF managed?
Flecainide is used when the patient feels symptoms are starting
Risk of flecainide converting AF into flutter with 1:1 AV conduction causing a very fast ventricular rate
What is ablation used for?
Where drug treatment for rate or rhythm is not adequate or tolerated
Left atrial ablation (remove abnormal electrical pathways)
or
AVN ablation and permanent pacemaker
Anticoagulation is still needed
What anticoagulants are used for AF?
First line
DOACs e.g. rivaroxaban
Second line
Warfarin- if DOACs are contraindicated
What is the mechanism of action of Dabigatran?
Direct thrombin inhibitor
How often are DOACs taken?
Apixaban and dabigatran
Twice daily
Edoxaban and rivaroxaban
Once daily
What agents can be used to reverse effects in uncontrolled life-threatening bleeding due to DOACs?
Andexanet alfa (apixaban and rivaroxaban)
Idarucizumab (dabigatran)
What are the advantages of DOACs vs Warfarin?
No monitoring needed
No issues with time in therapeutic range
No major interaction problems
Better at preventing strokes in AF
Lower bleeding risk
What is the INR (international normalised ration)?
Prothrombin time of an average healthy adult
INR of 1 is normal
INR target for AF is 2-3
What is TTR (time in therapeutic range)?
Percentage of time that INR is in target range
If the INR is too low patient is at risk of stroke
Too high patient is at risk of bleeding
What can be used to reverse effects of warfarin?
Vitamin K
What is CHA2DS2VASc for?
Tool used to assess if a patient with AF should start anticoagulation
C– Congestive heart failure
H – Hypertension
A2 – Age above 75
D – Diabetes
S2 – Stroke or TIA previously
V – Vascular disease
A – Age 65 – 74
S – Sex (female)
0- No anticoagulation
1- Consider in men (women automatically score 1)
2 - Offer anticoagulation
What is an ORBIT score used for?
Assessing risk of major bleeding in patients with AF taking anticoagulation
Over 75
Renal impairment (GFR < 60)
Bleeding previously (GI or intracranial bleeding
Iron (low Hb or haematocrit)
Taking antiplatelet medication
What is left atrial appendage occlusion?
Left atrial appendage is a small pouch where thrombi commonly form
Occlusion is where the septum is punctured to access the LA and a plug is placed to prevent blood entering that area
