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Core Conditions - Cardiovascular > Atrial Fibrillation > Flashcards

Atrial Fibrillation Flashcards

1
Q

What type of rhythm abnormality is AF?

What is more likely to cause it in acutely unwell patients and older patients?

A
  • AF is a common tachycardia
  • in an acutely unwell patient is can be caused by underlying illness, such as sepsis, pneumonia and hyperthyroidism
    • it may be reversible by treating the underlying cause
  • in older patients it tends to be found without an obvious precipitating factor
    • ​​this may be asymptomatic and found incidentally, or it may present with palpitations
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2
Q

Why is atrial fibrillation significant in the long term?

A

it increases the risk of stroke

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3
Q

What are the 2 main areas of management in AF?

A
  • managing the AF itself through either rate or rhythm control
  • assessing and managing the stroke risk with anticoagulation
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4
Q

What is the typical progressive disease pattern associated with chronic AF?

A
  • episodes of paroxysmal AF that are < 1 week in duration
    • often multiple episodes of this that may resolve before progressing
  • persistent AF where episodes are > 1 week in duration
  • long-term persistent where episodes > 12 months
  • permanent AF
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5
Q

What is AF associated with an increased risk of?

A

it is associated with an increased risk of stroke and heart failure

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6
Q

How does the prevalence of AF change with age?

What % of stroke patients have AF?

A
  • incidence increases with age
  • present in 2-4% of the general population
  • present in 5% of over 65s and 10% of over 70s
  • present in 15% of all stroke patients
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7
Q

What are the risk factors associated with AF?

A
  • obesity
  • hypertension
  • type 2 diabetes mellitus
  • obstructive sleep apnoea
  • smoking
  • coronary artery disease
  • valvular heart disease
  • heart failure
  • chronic kidney disease
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8
Q

What are the potentially reversible causes of AF?

A
  • excess alcohol consumption
  • hyperthyroidism
  • electrolyte abnormalities
  • sepsis
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9
Q

What are potential cardiac and pulmonary causes associated with acute presentation of AF?

A

Cardiac:

  • heart failure
  • heart ischaemia (MI)
  • hypertension
  • mitral valve disease
  • congenital heart disease (rare)

Pulmonary:

  • PE
  • pneumonia
  • bronchocarcinoma
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10
Q

What are other causes associated with acute presentation of AF?

A
  • hyperthyroidism (fast AF)
    • sometimes hypothyroidism can cause slow AF
  • alcohol
  • post-operatively
  • sepsis
  • high caffeine intake
  • antiarrhythmic drugs
  • hypokalaemia
  • hypermagnesemia
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11
Q

What is meant by the term “lone AF”?

A
  • this refers to cases of AF where no cause can be found
  • many cases initially labelled as lone AF have a cause discovered upon further investigation
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12
Q

How does AF usually present?

What type of pulse is present and what should be done in this scenario?

A
  • AF is usually asymptomatic, particularly in chronic AF
  • acutely it can present with:
    • palpitations
    • chest pain
    • dyspnoea
    • dizziness / syncope
  • it is associated with an irregularly irregular pulse
    • ​an ECG should be performed on everyone with an irregular pulse
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13
Q

What findings might be present on examination of someone with AF?

A
  • irregularly irregular pulse
  • apical pulse rate > radial pulse rate
  • 1st heart sound of varying intensity
  • signs of LV dysfunction
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14
Q

What are the indications for someone presenting with AF to be referred to the emergency department?

A
  • hypotension
  • “fast AF” with a ventricular rate > 110
  • significant symptoms
  • syncope or pre-syncope
  • chest pain
  • ECG showing ischaemic changes
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15
Q

What is involved in the pathology of AF?

What are the consequences of this condition on cardiac output?

A
  • AF causes an irregular atrial rhythm between 300 - 600 bpm
  • the AV node is unable to transmit beats as quickly as this, so it does so intermittently, resulting in an irregular ventricular rhythm
  • irregular stimulation of the ventricles reduces cardiac output by up to 20%, as well as allowing stasis of blood in the heart chambers
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16
Q

What ECG findings are typical in atrial fibrillation?

A
  • there are absent P waves with an irregular baseline
  • irregular ventricular rate (QRS complexes)
  • the QRS complex is normal shape as conduction through the AV node is normal
  • T waves are normal
  • In V1 the trace resembles atrial flutter
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17
Q

What blood tests are performed in atrial fibrillation and why?

A
  • U&Es to check for renal dysfunction
  • TFTs as AF can occur secondary to hyperthyroidism
  • cardiac enzymes
  • CMP - calcium, magnesium & phosphate
    • aim for magnesium > 1 in patients with AF (normal is 0.7 - 1.1)
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18
Q

What other investigations may be conducted in suspected AF?

A

Echocardiogram:

  • this is used to assess for structural heart disease
    • mitral valve disease
    • left ventricular dysfunction
    • left atrial enlargement

Polysomnography:

  • used to assess for sleep apnoea, which is an important risk factor
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19
Q

What are the 4 steps involved in management of a newly diagnosed AF patient?

A
  • identify any risk factors and reversible causes
  • characterise any structural heart disease that may be associated with AF
    • this typically involves sending a patient for an echocardiogram
  • assess and manage ventricular rate
  • consider anticoagulation
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20
Q

What is meant by “acute atrial fibrillation”?

Who does this tend to affect?

A
  • this is AF that is < 48 hours in duration
  • tends to affect younger patients
  • patients are likely to have an identifiable and reversible cause
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21
Q

What is involved in the treatment of acute atrial fibrillation?

A
  • treat the underlying condition (e.g. pneumonia, MI)
  • control the ventricular rate
  • consider anticoagulation
  • consider DC or drug cardioversion
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22
Q

What type of anticoagulation is recommended in acute AF?

Why is this performed?

What should be done if anticoagulants are contraindicated?

A
  • typically, heparin (5,000 - 10,000 U IV) is used in the acute setting
  • this is important as it prevents thrombus formation and thrombi are a contraindication for cardioversion
  • if anticoagulants are contraindicated, then a trans-oesophageal ultrasound (TOE) needs to be performed prior to mechanical cardioversion to rule out the presence of a thrombus
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23
Q

What should be done in an acutely ill patient with acute AF?

A

DC cardioversion

  • do not delay treatment to give anticoagulants
  • cardioversion should be performed in ITU with sedation
  • patient is shocked at 200J initially, and then 2 further attempts at 360J if this is unsuccessful
24
Q

What are the stages in management of a patient with chronic atrial fibrillation?

A
  • Identify and treat any reversible causes
  • send the patient for an echo to rule out any structural heart disease
  • control the ventricular rate and/or rhythm
  • assess the need for anticoagulation
25
Q

For most patients with chronic AF, rate control is considered as effective as rhythm control

What are the exceptions to this?

A
  • for most patients with chronic AF, rate control is considered as effective as rhythm control except for…
    • young patients
    • 1st episode of AF
    • significant heart failure
    • physically active patients
  • a rhythm control option should be considered in these patients
  • rate vs. rhythm control has no difference in long-term mortality, but rhythm control tends to result in fewer symptoms
26
Q

What are the 2 possible first line rate control treatments for chronic AF?

Can they be used together?

A

B-blocker or Ca2+ blocker

  • using both together is contraindicated as it can cause heart block
  • B-blockers are generally preferred
27
Q

Which beta-blockers are suitable for use in AF?

Which ones are preferred in heart failure?

A
  • atenolol
  • metoprolol
  • bisoprolol
  • carvedilol
  • nebivolol
  • bisoprolol, carvedilol and nebivolol are preferred in heart failure
28
Q

What calcium channel blockers are appropriate for use in chronic AF?

A

non-dihydropyridine calcium channel blockers

these are diltiazem and verapamil

29
Q

What is the second line rate control option in chronic AF?

A

beta-blocker or calcium channel blocker WITH digoxin or amiodarone

  • digoxin and amiodarone are antiarrhyhtmic medications used to treat an irregular heartbeat
  • digoxin as a sole treatment for AF is not widely acceptable and may only be suitable for some very sedentary elderly patients
30
Q

Which medication should B-blockers not be given with and why?

A
  • they should NOT be given with verapamil or diltiazem (L-type calcium channel blockers)
  • there is a risk of bradycardia and heart block
31
Q

What are the 4 different rhythm control options for chronic AF?

A
  • flecanide
    • only recommended for use in those with dangerous arrhythmias or when significant symptoms cannot be managed with other treatments
    • used to treat ventricular & supraventricular tachycardias
  • amiodarone
  • electrical cardioversion
  • catheter ablation
    • a catheter is passed through the blood vessels into the heart to stop abnormal electrical signals in the heart
32
Q

When is flecanide contraindicated?

A
  • left ventricular dysfunction
  • known coronary artery disease
  • left ventricular hypertrophy
33
Q

What are the possible risks associated with amiodarone?

A
  • it can cause thyrotoxicosis
  • it interacts with many other medications
  • it can cause liver impairment
  • long-term use increases risk of lung fibrosis
34
Q

When is catheter ablation most commonly used?

A

it is most commonly used in younger patients who have failed rhythm control with other options

35
Q

What score is used to assess the need for anticoagulation?

A

the CHA2DS2-VASc score

(Chads-Vasc)

after this, you then need to calculate the HAS-BLED score to determine the patient’s risk of bleeding

36
Q

What are the components involved in the CHADSVASc score?

How many points are awarded for each component?

A
  • C - congestive heart failure or LVEF < 40%
  • H - hypertension
  • A2 - age 75 or more
    • ​scores 2 points
  • D - diabetes
  • S2 - previous stroke, TIA or thromboembolism
    • ​scores 2 points
  • V - vascular disease
  • A - age 65-74
  • Sc - female gender
37
Q

How is the CHADS VASc score interpreted?

Which patients should be offered anticoagulation?

A
  • most patients with a score of 1 or more should be offered anticoagulation
  • anticoagulation is strongly recommended in patients scoring 2 or more
  • you then need to use the HASBLED score to calculate the risk of bleeding, as the risks of anticoagulation may outweigh the benefits
38
Q
A
39
Q

What are the different components involved in the HASBLED score?

A
  • H - hypertension
  • A - abnormal renal or liver function
  • S - previous history of stroke
  • B - previous history of major bleeding
  • L - labile INR (<60% of time in therapeutic range)
  • E - IV drug use
  • D - drug and alcohol use
    • NSAIDs, anti-platelet agents and alcohol >8 units / week
40
Q

How is the HASBLED score interpreted?

When does the risk of anticoagulation outweigh the benefit?

A
  • an answer of “yes” to each item is worth 1 point
  • a score of 3 or more indicates a high risk of bleeding
  • if patient is a high risk of bleeding then anticoagulation is not advisable as the risks outweigh the benefits
41
Q

What anticoagulants are generally preferred to be used instead of warfarin?

Why is this the case?

A

direct oral anticoagulants (DOACs)

  • this includes rivaroxaban, apixaban and dabigatran
  • they do not require monitoring of INR
  • they are less likely to interact with other drugs
  • they have standardised dosing
42
Q

How does rivaroxaban work?

A
  • it is an anticoagulant used to prevent blood clots
    • specifically used to treat DVT, PE and prevention of clots in AF
  • it inhibits factor Xa
  • this interrupts the intrinsic and extrinsic pathway of the blood coagulation cascade, which inhibits the formation of thrombin and development of thrombi
43
Q

How does apixaban work?

A
  • it is also a direct inhibitor of factor Xa
  • factor Xa catalyses the conversion of prothrombin to thrombin, which is responsible for fibrin clot formation
  • inhibiting factor Xa indirectly decreases clot formation induced by thrombin
44
Q

How does dabigatran work?

A
  • it reversibly binds to the active site on the thrombin molecule
  • this prevents thrombin-mediated activation of coagulation factors
  • it can inactivate thrombin even when it is fibrin-bound, meaning that it may enhance fibrinolysis
45
Q

When are DOACs not recommended?

What is the one downside of using this medication?

A
  • they are not recommended for use when structural heart disease is present
  • DOACs are less easily reversible than warfarin
46
Q

What is paroxysmal AF?

What method is used for treatment of this condition and what 2 criteria must be present in order for this to be suitable?

A
  • this is a condition in which short spells of AF come and go
    • upon investigations, the patient may often be in sinus rhythm
  • the “pill in the pocket” treatment method is used
  • this involves flecainide or solatol PRN - which are drugs that control the rhythm
  • this is only suitable if systolic BP > 100 and there is no underlying LV dysfunction
47
Q

What is the 1st line treatment for paroxysmal AF in older and younger patients?

A
  • first line treatment involves sotolol / bisoprolol (beta-blockers)
  • in young patients, first line treatment involves flecainide / verapamil
  • ^ should be avoided in older patients as they are negatively inotropic (and cause vasodilatation)
48
Q

What are the 2nd and 3rd line treatments for paroxysmal AF?

When do these tend to be used?

A
  • 2nd line is amiodarone which tends to be used in those with some LV dysfunction
  • 3rd line is digoxin, which is used in those with severe LV dysfunction as it is positively inotropic
    • this tends to have a weak effect and takes several weeks to become effective
49
Q

When is cardioversion used for rhythm control in acute AF?

A
  • when the symptoms have been ongoing for < 48 hours
  • often amiodarone will also have been given to these patients
50
Q

When might cardioversion be used for rhythm control in chronic AF?

What is a good marker of outcome from this?

What treatment needs to be stopped prior to the treatment?

A
  • when patient has had > 3 weeks of anticoagulant therapy AND TOE has proven no thrombus
  • LV dilation is a good predictor of outcome
    • those with a LV diameter > 5.5cm are unlikely to have a successful cardioversion
  • if the patient is on digoxin, this needs to be stopped a few days before treatment
51
Q

Which drugs are typically used for drug cardioversion?

A
  • amiodarone is the drug of choice, which can be given IV or PO
  • flecainide may be used in patients with no known IHD or WPW syndrome
    • this is negatively inotropic (reduces the strength of contractions)
52
Q

If paroxysmal AF is reversed, when should anticoagulation therapy be continued?

A
  • it may be continued even if normal sinus rhythm has been restored if other risk factors are still present
  • the CHADS VASc score should be used to determine this
  • anticoagulation should only be discontinued if sinus rhythm is present and there are no risk factors for emboli (CHADS = 0)
53
Q

What is the major complication associated with AF?

How can this be prevented?

A

thrombo-embolic stroke

  • the degree of anticoagulant therapy required in AF can be assessed using CHADS VASc score
  • any score above 2 requires anticoagulation with warfarin
54
Q

Why should warfarin not be given to patients at low risk of stroke (CHADS < 2)?

A
  • warfarin in itself can be a stroke risk as it can cause a bleed
  • it should only be given to high-risk patients with a CHADs score > 2
55
Q

What other group of patients may the risk of giving warfarin outweigh the benefits?

A
  • patients at high risk of falls (typically elderly with many co-morbidities)
  • the risk from fall, and subsequent bleed, may be greater than the risk of stroke
56
Q

Why do many patients undergo TOE?

What is this an attempt to visualise?

A
  • thrombus formation most commonly occurs in the left atrial appendage
  • this is very difficult to view on transthoracic echo
  • many AF patients undergo TOE as the echo transducer is right next to the left atrium, so this gets a good view
57
Q
A

Core Conditions - Cardiovascular (6 decks)

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