Atrial Fibrillation

Question 1

What are the most common causes of AF?

Answer 1

mrs SMITH 
S- sepsis 
M- mitral valve stenosis / regurgitation 
I – ischaemic heart disease
T - thyrotoxicosis
H – hypertension

Question 2

What are the signs and symptoms of AF?

Answer 2

Often asymptomatic

But signs and symptoms reported can be:

• Palpitations
• Chest pain
• Dyspnea
• Irregularly irregular pulse
• Syncope
• Symptoms of associated conditions e.g. storke, sepsis or thyrotoxicosis

Question 3

What is the first line investigation of AF? What findings would indicate AF?

Answer 3

• ECG  fibrillatory waves (f)
  o Missing p waves  disorganised electrical activity overrides the organised activity from the sinoatrial node.
  o Irregular R-R intervals  irregular conduction of electrical impulses to the ventricles.
  o Narrow QRS complexes

Question 4

What are the two-differential diagnosis for an irregularly irregular pulse?

How do you differentiate between the two differentials?

Answer 4

• Atrial fibrillation
• Ventricular ectopics
  o To differentiate ventricular ectopics  heart rate becomes regular in patients with ventricular ectopics as ventricular ectopics disappear once the heart gets over a certain threshold. This does not happen with AF.

Question 5

What are the underlying principles of managing atrial fibrillation?

Answer 5

Rate/Rythm Control
Reducing risk of stroke (anti-coagulants).

See diagram in AF and management word document.

Question 6

Why is cardioversion only considered for patients that have AF presentation < 48 hours or have been anticoagulated for a period of time before attempting cardioversion?

Answer 6

• The moment a patient switches from AF to sinus rhythm presents the highest risk for embolism leading to stroke.

To minimise this risk, patients must have either a short duration of symptoms (less than 48 hours) or be anticoagulated for a period of time prior to attempting cardioversion.

Question 7

What tools do you use to assess the risk of coagulation and bleeding?

What score do you need to indicate your high risk of coagulation?

Answer 7

Use 2 tools

• CHA2-DS2-VASc score.
• HASBLED score

CHA2-DS2-VASc score
> Congestive Heart failure 
> Hypertension 
> Age (2pts >75yr, 1pt 65-74yrs)
> D- Diabetes 
> S2 --> stroke or TIA 
>V --> Vascular Disease (including IHD and peripheral vascular disease).
>S --> Sex (female).

CHA2-DS2-VASc

• 0 points  no anti-coagulation (but do a trans-thoracic echo to rule out valvular heart disease)
• 1 point  if male, start anti-coagulant therapy, if female no
• 2+ points  consider anti-coagulant therapy (offer a choice including warfarin and NOACs).

HASBLED 
Hypertension 
A- Abnormal liver and/or kidney function 
S- Stroke (history)
B- Bleeding (Hx or tendency)
L- Labile INRs whilst on warfarin 
E- Elderly 
D- Drugs e.g. NSAIDs, anti-platelets, alcohol (>8 units a week). 

Score of 3+ indicates high risk of bleeding.

Question 8

What is meant by pro-thrombin time and INR?

What does an INR of 2 suggest?

What is the target INR for AF?

Answer 8

Prothrombin time–> time it takes for the blood to clot.

INR ==> Assessment of prothrombin time of a patient compared to a normal healthy adult.

INR 2 ==> it takes twice as long to clot as that of a normal healthy adult.

INR for AF –> 2-3

Question 9

What is warfarin metabolised by?

What is the anti-dote for warfarin?

What drugs/lifestyle factors/dietary components interfere with the activity of warfarin/its metabolism?

Half-life of warfarin?

Answer 9

cytochrome P450 system

Vitamin K

Antibiotics affect the activity of P450 system. INR is also affected by foods that have vitamin k (e.g. green leafy retables), or those that affect the P450 (e.g. alcohol). So its important to monitor INR whenever there are any changes to the life-style or drugs in patients being treated with warfarin.

Half-life = 1-3 days

Question 10

Examples of NOACs?

Half-life of NOACs?

Advantages of NOACs over warfarin?

Answer 10

Apixaban, rivaroxaban and dabigatran

7-15 hours

> Similar stroke and bleeding risk as warfarin (or lower).
No monitoring is required
No major interaction problems.

Question 11

What is paroxysmal AF?

How do you treat it?

What do you need to check before starting this treatment?

Contraindications to this drug?

Answer 11

AF that comes and goes in episodes, usually lasting more than 48 hours.

Flecanide (pill in pocket) approach

Need to check if they have a structural heart defect.

Also need to avoid flecanide in patients with atrial flutter as it can cause 1:1 AV conduction and lead to significant tachycardia.