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Yr 4 - CCC > Cardiology: Atrial Fibrillation > Flashcards

Cardiology: Atrial Fibrillation Flashcards

1
Q

What is AF?

A

A condition where the electrical activity in the atria of the heart becomes disorganised, leading to fibrillation (random muscle twitching) of the atria and an irregularly irregular pulse.

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2
Q

Features of AF?

A

1) Irregularly irregular ventricular contractions
2) Tachycardia
3) Heart failure due to impaired filling of the ventricles during diastole
4) Increased risk of stroke

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3
Q

What node produces organised electrical activity that coordinates the contraction of the atria?

A

Sinoatrial node

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4
Q

Pathophysiology in AF?

A

AF occurs when electrical activity is disorganised, causing the contraction of the atria to become uncoordinated, rapid and irregular.

This chaotic electrical activity overrides the regular, organised activity from the SA node.

It passes through to the ventricles, resulting in irregularly irregular ventricular contraction.

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5
Q

How does AF increase the risk of stroke?

A

1) Uncoordinated atrial activity means the blood can stagnate in the atria, forming a blood clot (thrombus)

2) A thrombus formed in the left atrium may travel to the brain and block a cerebral artery –> ischaemi stroke

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6
Q

What is increased risk of stroke in AF patients?

A

5x higher

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7
Q

What are the 5 most common causes of AF?

Mneumonic: SMITH

A

S - Sepsis
M - Mitral valve pathology (stenosis or regurgitation)
I - IHD
T - Thyrotoxicosis
H - HTN

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8
Q

What 2 lifestyle factors can cause AF?

A

1) Alcohol
2) Caffeine

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9
Q

Presentation of AF?

A
  • Often asymptomatic (often incidental finding e.g. after stroke)
  • Palpitations
  • Shortness of breath
  • Dizziness or syncope (loss of consciousness)
  • Symptoms of associated conditions (e.g., stroke, sepsis or thyrotoxicosis)
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10
Q

What is the key exam finding in AF?

A

Irregularly irregular pulse

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11
Q

What are the 2 main differentials for an irregularly irregular pulse?

A

1) AF
2) Ventricular ectopics

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12
Q

When do ventricular atopics disappear?

A

Ventricular ectopics disappear when the heart rate gets above a certain threshold.

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13
Q

With an irregularly irregular pulse, what does a regular heart rate during exercise suggest a diagnosis of ?

A

Ventricular ectopics

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14
Q

What investigation is required in all patients with an irregularly irregular pulse?

A

ECG

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15
Q

3 key ECG findings in AF?

A

1) Absent P waves
2) Narrow QRS complex tachycardia
3) Irregularly irregular ventricular rhythm

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16
Q

An echo can be used to investigate further in AF in cases of what?

A

1) Valvular heart disease
2) Heart failure
3) Planned cardioversion

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17
Q

What is paroxysmal AF?

A

episodes of atrial fibrillation that reoccur and spontaneously resolve back to sinus rhythm

(can last between 30 seconds and 48 hours)

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18
Q

Patients with a normal ECG and suspected paroxysmal atrial fibrillation can have further investigations.

What are 2 further investigations?

A

1) 24-hour ambulatory ECG (Holter monitor)
2) Cardiac event recorder lasting 1-2 weeks

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19
Q

What is valvular AF?

A

AF with significant mitral stenosis or a mechanical heart valve.

The assumption is that the valvular pathology has led to atrial fibrillation

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20
Q

What are the 4 types of AF?

A

1) first detected episode
2) paroxysmal
3) persistent
4) permanent

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21
Q

If episodes of AF terminate spontaneously, what is this called?

A

Paroxysmal

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22
Q

If episodes of AF are not self-terminating (usually last >7 days) what term is used?

A

Persistent

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23
Q

What is permanent AF?

A

in permanent AF there is continuous atrial fibrillation which cannot be cardioverted or if attempts to do so are deemed inappropriate.

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24
Q

What are the 2 key aspects of AF management?

A

1) rate or rhythm control –> beta blocker e.g. bisoprolol

2) stroke prevention; anticoagulation –> DOAC

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25
Q

Aim of rate control in AF?

A

Rate control aims to get the heart rate below 100

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26
Q

NICE guidelines (2021) suggest all patients with AF should have rate control as first-line.

What are 4 exceptions to this?

A

1) A reversible cause for their AF

2) New onset atrial fibrillation (within the last 48 hours)

3) Heart failure caused by atrial fibrillation

4) Symptoms despite being effectively rate controlled

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27
Q

What are 3 pharmacological options for rate control in AF?

A

1) beta blocker

2) Calcium-channel blocker (e.g.,
diltiazem or verapamil) (not preferable in heart failure)

3) Digoxin (only in sedentary people with persistent atrial fibrillation, requires monitoring and has a risk of toxicity)

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28
Q

What is the 1st line option for rate control in AF?

A

Beta blocker e.g. bisoprolol, atenolol

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29
Q

Aim of rhythm control in AF?

A

return the patient to normal sinus rhythm.

30
Q

Rhythm control may be offered to patients with AF.

What are the 4 indications for rhythm control?

A

1) A reversible cause for their AF

2) New onset atrial fibrillation (within the last 48 hours)

3) Heart failure caused by atrial fibrillation

4) Symptoms despite being effectively rate controlled

31
Q

What are 2 options for rhythm control in AF?

A

1) cardioversion
2) long-term rhythm control using medications

32
Q

What are the 2 types of cardioversion?

A

1) immediate
2) delayed

33
Q

When is immediate cardioversion used in AF?

A

1) AF present for <48 hours
2) Causing life-threatening haemodynamic instability

34
Q

What are the 2 options for immediate cardioversion in AF?

A

1) pharmacological cardioversion
2) electrical cardioversion

35
Q

What are the 2 options for pharmacological cardioversion?

A

1) flecainide
2) amiodarone

36
Q

What is the drug of choice for pharmacological cardioversion in patients with structural heart disease?

A

amiodarone

37
Q

What is the aim of electrical cardioversion?

A

Electrical cardioversion aims to shock the heart back into sinus rhythm using a cardiac defibrillator (done under sedation or general anaesthesia)

38
Q

When is delayed cardioversion used in AF?

A

Delayed cardioversion is used if the atrial fibrillation has been present for more than 48 hours and they are stable.

39
Q

What is recommended for delayed cardiversion?

A

Electrical cardioversion

40
Q

What can be considered before and after electrical cardioversion to prevent AF from recurring?

A

Amiodarone

41
Q

How long should the patient should be anticoagulated for before delayed cardioversion?

A

at least 3 weeks

42
Q

What is first line option for long-term rhythm control?

A

Beta blockers

43
Q

What are 3 pharmacological options for long term rhythm control?

A

1) beta blockers
2) Dronedarone
3) Amiodarone

44
Q

Management of paroxysmal AF?

A

Patients may be appropriate for a “pill-in-the-pocket” approach –> they take a pill to terminate their AF only when they feel the symptoms starting.

Anticoagulation based on CHA2DS2-VASc score

45
Q

Criteria for ‘pill in the pocket’ approach?

A

To be suitable for a pill-in-the-pocket approach, they must have infrequent episodes without structural heart disease.

They also need to be able to identify the signs of atrial fibrillation and understand when to take the treatment.

46
Q

What is the usual treatment for a pill-in-the-pocket approach?

A

Flecainide

47
Q

Where drug treatment for rate or rhythm control is not adequate or tolerated, what is next option?

A

Ablation

48
Q

What are the 2 options for ablation in AF?

A

1) Left atrial ablation

2) Atrioventricular node ablation and a permanent pacemaker

49
Q

Aim of ablation?

A

Burn area of abnormal electrical activity –> leaves scar tissue that does not conduct electrical activity.

The aim is to remove the source of the arrhythmia and restore normal sinus rhythm.

50
Q

What is required post atrioventricular node ablation and a permanent pacemaker?

A

1) Permanent pacemaker to control ventricular contraction

2) Anticoagulation

51
Q

What are 2 options for anticoagulation in AF?

A

1) DOACs –> 1st line
2) Warfarin –> if DOACs contraindicated

52
Q

Every patient with a head injury whilst taking anticoagulation should have what investigation?

A

CT head to assess for an intracranial bleed

53
Q

Some of the DOACs have agents available to reverse the effects in uncontrolled or life-threatening bleeding.

What is reversing agent for apixaban and rivaroxaban?

A

Andexanet alfa

54
Q

What is reversing agent for idarucizumab?

A

a monoclonal antibody against dabigatran

55
Q

Advantages of DOACs over warfarin?

A

1) No monitoring is required
2) No issues with time in therapeutic range (provided they have good adherence)
3) No major interaction problems
4) Equal or slightly better than warfarin at preventing strokes in atrial fibrillation
5) Equal or slightly lower risk of bleeding than warfarin

56
Q

What are the 3 most common indications for DOACs?

A

1) stroke prevention in patients with AF

2) Treatment of DVT and PE

3) Prophylaxis of VTE after hip or knee replacement

57
Q

Mechanism of warfarin?

A

Vitamin K antagonist –> prolongs prothrombin time

58
Q

What is used to assess how anticoagulated the patient is by warfarin?

A

INR

59
Q

What does the INR calculate?

A

The INR calculates the patient’s prothrombin time compared with the prothrombin time of an average healthy adult.

60
Q

What does an INR of 2 mean?

A

An INR of 2 means the patient has a prothrombin time twice that of an average healthy adult (it takes them twice as long to form a blood clot).

61
Q

Target INR for AF?

A

2-3

62
Q

What is the time in therapeutic range (TTR)?

A

Refers to the percentage of time that the INR is in the target range.

63
Q

Is warfarin metabolised by the P450?

A

yes

64
Q

What foods can affect warfarin levels?

A
  • leafy green vegetables (contain vitamin K)
  • cranberry juice & alcohol (affect P450)
65
Q

What can reverse the effects of warfarin?

A

Vitamin K can reverse the effects of warfarin in the event of a very high INR or significant bleeding.

66
Q

What tool is used for assessing whether a patient with atrial fibrillation (even if its first episode) should start anticoagulation?

A

CHA2DS2-VASc

67
Q

What does a higher CHA2DS2-VASc indicate?

A

The higher the score, the higher the risk of developing a stroke or TIA.

68
Q

Describe the CHA2DS2-VASc

A

Each factor scores a point:

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)

69
Q

CHA2DS2-VASc score results:

A

0 – no anticoagulation

1 – consider anticoagulation in men (women automatically score 1)

2 or more – offer anticoagulation

70
Q

What score is used or assessing the risk of major bleeding in patients with atrial fibrillation taking anticoagulation?

A

ORBIT score

O – Older age (age 75 or above)
R – Renal impairment (GFR less than 60)
B – Bleeding previously (history of gastrointestinal or intracranial bleeding)
I – Iron (low haemoglobin or haematocrit)
T – Taking antiplatelet medication

71
Q

What is an option for patients with contraindications to anticoagulation and a high stroke risk in AF?

A

Left atrial appendage occlusion

72
Q
A

Yr 4 - CCC (54 decks)

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