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Finals: Medicine > Atrial fibrillation (AF) > Flashcards

Atrial fibrillation (AF) Flashcards

1
Q

Describe the pathogenesis of atrial fibrillation (AF)

A

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

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2
Q

Name some of the aetiology of atrial fibrillation (AF)

A

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
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3
Q

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

A

Hypertension or Ischaemic heart disease

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4
Q

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

A

Rheumatic heart disease

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5
Q

Rheumatic heart disease typically affecting which heart valve?

A

Mitral valve

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6
Q

Name the two major complications of atrial fibrillation (AF)

A

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

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7
Q

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

A

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
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8
Q

What pulse rhythm is suggestive of atrial fibrillation (AF)

A

Irregularly irregular rhythm

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9
Q

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

A

Irregularly irregular rhythm

Absence of P waves

Irregular, fibrillating baseline

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10
Q

Management of AF comprises a combination of 3 components.

Name these components?

A

Rate control OR rhythm control

+/-

Anticoagulation to prevent thromboembolic events

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11
Q

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

A

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
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12
Q

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

a) Rate control
b) Rhythm control

A

b) Rhythm control

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13
Q

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

a) Rate control
b) Rhythm control

A

b) Rhythm control

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14
Q

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

a) Rate control
b) Rhythm control

A

b) Rhythm control

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15
Q

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

a) Rate control
b) Rhythm control

A

b) Rhythm control

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16
Q

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

A
  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
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17
Q

Name the first line pharmaceutical agents for rate control of AF

A

Beta blocker e.g. Bisoprolol

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18
Q

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

A

Technically contraindicated in COPD and asthma

Cannot be used in hypotension because it will drop blood pressure

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19
Q

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

A

Calcium-channel blocker e.g. diltiazem

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20
Q

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

A

Digoxin could be considered only in sedentary people

Needs monitoring due to the risk of toxicity

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21
Q

What is the most commonly used beta-blocker in AF

A

Bisoprolol

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22
Q

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

A

Contraindicated in heart failure

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23
Q

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

A

Diltiazem or verapamil

24
Q

Why should digoxin be avoided in younger patients

A

Increases cardiac mortality

25
Q

Rhythm control aims to restore and/or maintain the heart in normal sinus rhythm.

Name the two methods rhythm control can be achieved

A
  1. Electrical cardioversion
  2. Pharmacological cardioversion e.g. amiodarone, flecainide, Sotalol
26
Q

Describe what is involved in electrical cardioversion to rhythm control AF

A

Single event – shocks the heart back into sinus rhythm

27
Q

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

A

Flecainide

Amiodarone

28
Q

Describe the dosage of flecainide for pharmaceutical rhythm control of AF

A

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

29
Q

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

A

Can induce fatal arrhythmias in structurally abnormal hearts

30
Q

Amiodarone is used for:

a) Rate control for AF
b) Rhythmg control of AF

A

Both

Rate and rhythm control

31
Q

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

A

Sotalol – beta blocker with additional K channel blocker action

32
Q

When is anticoagulation used in AF

A

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

33
Q

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

A

CHA2DS2-VASc scoring

34
Q

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

A

CHA2DS2-VASc scoring

AND

ORBIT Scoring

35
Q

Which of the risk stratification tools used to in the anticoagulation for AF assesses a patients risk of emboli formation:

a) CHA2DS2-VASc scoring
b) ORBIT Scoring

A

a) CHA2DS2-VASc scoring

36
Q

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

A

b) ORBIT Scoring

37
Q

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

A

ORBIT Scoring

38
Q

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

A

Score ≥1: Start anticoagulation therapy in males

Score ≥ 2: Start anticoagulation therapy in females

39
Q

What are the components of the CHA2DS2-VASc scoring

A
40
Q

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?

A

Range: 0-7

  • Score of 4-7: high risk
  • Score of 3: Medium risk
  • Score of 0-2: Low risk
41
Q

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

A

Score of 4-7

42
Q

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

A

Score of 3

43
Q

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

A

Score 0-2

44
Q

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?

A

Direct oral anticoagulants (DOACs)

45
Q

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?

A

Vitamin K antagonist (e.g. warfarin)

46
Q

Name the Vitamin K-dependent clotting factors

A

Factor II (Prothrombin)

VII

IX

Protein C and S

47
Q

Describe the mechanism of action of warfarin

A

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

48
Q

Where is warfarin metabolised?

A

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

49
Q

What does INR stand for and what does it measure?

A

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

50
Q

What is the typical INR target range?

A

Normal INR target is usually 2 – 3

51
Q

How is INR measured?

A

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)

52
Q

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

A

Vitamin K

53
Q

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

A

Apixaban

Rivaroxaban

54
Q

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

A

Dabigatran

55
Q

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

A

Andexanet alfa

56
Q

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

A

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

57
Q

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

A

Idarucizumab (a monoclonal antibody against dabigatran)

Finals: Medicine (91 decks)

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