Atrial fibrillation (AF)

Question 1

Describe the pathogenesis of atrial fibrillation (AF)

Answer 1

Atrial fibrillation (AF) occurs when there is uncoordinated, rapid and irregular atrial contraction

Delay at the atrio-ventricular (AV) node means that only some of the atrial impulses are conducted to the ventricles, resulting in an irregular ventricular response

Question 2

Name some of the aetiology of atrial fibrillation (AF)

Answer 2

Cardiac

• Hypertension – most common cause in developed countries
• Ischaemic heart disease – most common cause in developed countries
• Valvular disease e.g. Rheumatic heart disease, which typically affecting the mitral valve – most common cause in less developed countries

Non-cardiac

• Respiratory e.g. COPD, pneumonia, PE
• Endocrine e.g. Hyperthyroidism, DM
• Infective e.g. sepsis
• Drugs e.g. bronchodilators, thyroxine
• Lifestyle factors e.g. alcohol abuse, excessive caffeine, obesity
• Electrolyte disturbances e.g. hypokalaemia, hypomagnesaemia

Question 3

What is the most common cause of atrial fibrillation (AF) is the developed world

Answer 3

Hypertension or Ischaemic heart disease

Question 4

What is the most common cause of atrial fibrillation (AF) is the developing world

Answer 4

Rheumatic heart disease

Question 5

Rheumatic heart disease typically affecting which heart valve?

Answer 5

Mitral valve

Question 6

Name the two major complications of atrial fibrillation (AF)

Answer 6

Thrombus formation due to the poor coordination of the atrial contraction leads to stasis of blood within the atria. It can break off forming an embolus and block distal arteries causing:

• Cerebral embolus: acute stroke or TIA
• Limb embolus: acute ischaemic limb
• Abdominal embolus: acute mesenteric ischaemia, ischaemic hepatitis
• Lungs embolus: PE

Heart failure due to poor filling of the ventricles during diastole

Question 7

Name some of the clinical features of atrial fibrillation (AF)

Answer 7

Symptoms:

• Asymptomatic - in most cases
• Palpitations
• Shortness of breath
• Syncope/Presyncope
• Symptoms of associated conditions e.g. stroke, sepsis or thyrotoxicosis

Signs

• Irregularly irregular pulse rate
• Absent ‘a’ wave on the jugular venous pressure
• Tachycardia
• Hypotension
• Features suggestive of the underlying cause e.g. hyperthyroidism, alcohol excess etc
• Features suggestive of complications resulting from the AF e.g. heart failure

Question 8

What pulse rhythm is suggestive of atrial fibrillation (AF)

Answer 8

Irregularly irregular rhythm

Question 9

Name the 3 hallmark ECG features of atrial fibrillation (AF)

Answer 9

Irregularly irregular rhythm

Absence of P waves

Irregular, fibrillating baseline

Question 10

Management of AF comprises a combination of 3 components.

Name these components?

Answer 10

Rate control OR rhythm control

+/-

Anticoagulation to prevent thromboembolic events

Question 11

Is rate or rhythm control the first line management for atrial fibrillation (AF)

Answer 11

Rate control is the most common type of management

Rate control is the first-line strategy unless:

• Reversible cause of the AF
• New-onset (onset <48 hours)
• AF is caused by heart failure
• They remain symptomatic despite being effectively rate controlled

Question 12

What is the first line strategy in patients with new-onset AF (onset <48 hours):

a) Rate control
b) Rhythm control

Answer 12

b) Rhythm control

Question 13

What is the first line strategy in patients with a reversible cause of the AF:

a) Rate control
b) Rhythm control

Answer 13

b) Rhythm control

Question 14

What is the first line strategy in patients with AF secondary to heart failure:

a) Rate control
b) Rhythm control

Answer 14

b) Rhythm control

Question 15

What is the first line strategy in patients with symptomatic AF despite effective rate control:

a) Rate control
b) Rhythm control

Answer 15

b) Rhythm control

Question 16

Name the 4 incidences in which rhythm control would be the first-line strategy in the management of the AF?

Answer 16

1. Reversible cause of the AF
2. New-onset (onset <48 hours)
3. AF is caused by heart failure
4. They remain symptomatic despite being effectively rate controlled

Question 17

Name the first line pharmaceutical agents for rate control of AF

Answer 17

Beta blocker e.g. Bisoprolol

Question 18

When would beta blocker be contraindicated as the first line pharmaceutical agents for rate control of AF

Answer 18

Technically contraindicated in COPD and asthma

Cannot be used in hypotension because it will drop blood pressure

Question 19

Name the second line pharmaceutical agents for rate control of AF (if they cant have beta blocker for whatever reason)

Answer 19

Calcium-channel blocker e.g. diltiazem

Question 20

When would digoxin be a good option as the pharmaceutical agents for rate control AF and what needs to be put in place in order to safely use it

Answer 20

Digoxin could be considered only in sedentary people

Needs monitoring due to the risk of toxicity

Question 21

What is the most commonly used beta-blocker in AF

Answer 21

Bisoprolol

Question 22

When would calcium channel blocker be contraindicated as the first line pharmaceutical agents for rate control of AF

Answer 22

Contraindicated in heart failure

Question 23

What is the most commonly used calcium channel blocker in the rate control of AF

Answer 23

Diltiazem or verapamil

Question 24

Why should digoxin be avoided in younger patients

Answer 24

Increases cardiac mortality

Question 25

Rhythm control aims to restore and/or maintain the heart in normal sinus rhythm. Name the two methods rhythm control can be achieved

Answer 25

1. Electrical cardioversion 2. Pharmacological cardioversion e.g. amiodarone, flecainide, Sotalol

Question 26

Describe what is involved in electrical cardioversion to rhythm control AF

Answer 26

Single event – shocks the heart back into sinus rhythm

Question 27

What is the first line pharmacological cardioversion therapy for rhythm control of AF

Answer 27

Flecainide Amiodarone

Question 28

Describe the dosage of flecainide for pharmaceutical rhythm control of AF

Answer 28

Can be either given regularly or as a "pill in the pocket" when symptoms come on

Question 29

Name an adverse effect of flecainide, a drug used in the pharmacological cardioversion of rhythm controlled AF

Answer 29

Can induce fatal arrhythmias in structurally abnormal hearts

Question 30

Amiodarone is used for: a) Rate control for AF b) Rhythmg control of AF

Answer 30

Both Rate and rhythm control

Question 31

What is the **second** line pharmacological cardioversion therapy for rhythm control of AF

Answer 31

**Sotalol** – beta blocker with additional K channel blocker action

Question 32

When is anticoagulation used in AF

Answer 32

In patients at high risk of developing a thrombus as a result of the AF or at high risk of bleeding There risk is determined by various risk stratification tools e.g. CHA₂DS₂-VASc scoring and ORBIT Scoring

Question 33

Name the risk stratification tool used to assess a patient's annual risk of developing an embolic event in patients with AF

Answer 33

CHA₂DS₂-VASc scoring

Question 34

Name the two risk stratification tools used to guide the need for anticoagulation therapy in patients with atrial fibrillation (AF)

Answer 34

CHA₂DS₂-VASc scoring AND ORBIT Scoring

Question 35

Which of the risk stratification tools used to in the anticoagulation for AF assesses a patients risk of emboli formation: ## Footnote a) CHA2DS2-VASc scoring b) ORBIT Scoring

Answer 35

a) CHA2DS2-VASc scoring

Question 36

Which of the risk stratification tools used to in the anticoagulation for AF assess patients risk of major bleeding events on anticoagulation. a) CHA2DS2-VASc scoring b) ORBIT Scoring

Answer 36

b) ORBIT Scoring

Question 37

Name the risk stratification tool used to assess patients (with AF) risk of major bleeding events on anticoagulation

Answer 37

ORBIT Scoring

Question 38

What CHA₂DS₂-VASc score should a patient start anticoagulation therapy?

Answer 38

Score ≥1: Start anticoagulation therapy in males Score ≥ 2: Start anticoagulation therapy in females

Question 39

What are the components of the CHA₂DS₂-VASc scoring

Answer 39

Question 40

ORBIT Scoring is used as a risk stratification tool to assess patients with AF's risk of major bleeding events on anticoagulation. Describe the intrepreation of the ORBIT scoring?

Answer 40

Range: 0-7 * Score of 4-7: high risk * Score of 3: Medium risk * Score of 0-2: Low risk

Question 41

An ORBIT score of what suggests a patient is a high risk of major bleeding events on anticoagulation

Answer 41

Score of 4-7

Question 42

An ORBIT score of what suggests a patient is a medium risk of major bleeding events on anticoagulation

Answer 42

Score of 3

Question 43

An ORBIT score of what suggests a patient is a **low** risk of major bleeding events on anticoagulation

Answer 43

Score 0-2

Question 44

If a patient was started on a pharmaceutical agents for anticoagulation for their AF. What is the first line pharmaceutical agent they would be offered?

Answer 44

Direct oral anticoagulants (DOACs)

Question 45

If you wanted to start a patient of a pharmaceutical agent for anticoagulation in AF but direct oral anticoagulants (DOACs) were not suitable or not tolerated. What is a suitable alternative?

Answer 45

Vitamin K antagonist (e.g. warfarin)

Question 46

Name the Vitamin K-dependent clotting factors

Answer 46

Factor II (Prothrombin) VII IX Protein C and S

Question 47

Describe the mechanism of action of warfarin

Answer 47

Warfarin blocks vitamin K and thus prolongs the prothrombin time, which is the time it takes for blood to clot

Question 48

Where is warfarin metabolised?

Answer 48

Warfarin is metabolised by the cytochrome P450 system in the liver Thus INR will be affected by other drugs that influence the activity of the P450 system e.g. clarithromycin

Question 49

What does INR stand for and what does it measure?

Answer 49

INR (international normalised ratio) measurement are required to assess how anticoagulated the patient is

Question 50

What is the typical INR target range?

Answer 50

Normal INR target is usually 2 – 3

Question 51

How is INR measured?

Answer 51

INR is a calculation of how the prothrombin time of the patient compares with the prothrombin time of a normal health adult. An INR of 1 indicates a normal prothrombin time. An INR of 2 indicates that the patient has a prothrombin time twice that of a normal healthy adult (it takes them twice as long to form a blood clot)

Question 52

When there is uncontrolled or life-threatening bleeding, the anticoagulant effects of warfarin can be reversed using what agent?

Answer 52

Vitamin K

Question 53

Give 2 examples of direct Xa inhibitors (a type of direct-acting oral anticoagulants (DOACs))

Answer 53

Apixaban Rivaroxaban

Question 54

Give an example of a Direct thrombin inhibitors (a type of direct-acting oral anticoagulants (DOACs))

Answer 54

Dabigatran

Question 55

When there is uncontrolled or life-threatening bleeding, the anticoagulant effects of **Direct Xa inhibitors** can be reversed using what agent

Answer 55

Andexanet alfa

Question 56

When there is uncontrolled or life-threatening bleeding, the anticoagulant effects of **apixaban** can be reversed using what agent

Answer 56

Andexanet alfa is the reversible agent of Direct Xa inhibitors e.g. apixaban

Question 57

When there is uncontrolled or life-threatening bleeding, the anticoagulant effects of **Direct thrombin inhibitors** can be reversed using what agent

Answer 57

**Idarucizumab** (a monoclonal antibody against dabigatran)