Atrial fibrillation Flashcards

1
Q

Atrial fibrillation (AF)

A

Atrial fibrillation (AF) is a supraventricular arrhythmia of the heart in which there is a lack of co-ordinated conduction in the atria. Electrical impulses are fired off from different parts of the atria and this leads to a reduced functional ability of the atria to pump blood effectively and smoothly. Electrical impulses transmitted from the atria via the AV node cause an irregular transmission to the ventricles leading to an irregular ventricular rate. The ventricles can beat up to 150 beats / minute or higher and it is this rapid and irregular ventricular rate which is the cause of many symptoms of AF. Usually patients with AF who have symptoms have a ventricular rate of greater than 90 beats/minute at rest. This increases to more than 110 beats/minute with mild to moderate exercise or activity.

The type of AF whose underlying cause is not linked to heart valve damage is known as non-valvular AF.

By contrast, valvular AF results from damage to the heart valves as a result of congenital heart disease or structural changes to the valves arising from underlying disease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Epidemiology

A

AF is the most common type of ‘sustained’ cardiac arrhythmia and, according to NICE (2014) the condition occurs in approximately 1.6% of the population in England and Wales. Its prevalence increases with age, estimates being 1-2% for those aged 50-59 years and rising to a prevalence of around 24% in those aged 80-89 years. Males are twice as likely to be affected as females.

The condition is thought to be underdiagnosed in the general population.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Risk factors

A

Common predisposing factors include both non-cardiac and cardiac causes. The list is not exhaustive but includes:

Increasing age
Gender
Hypertension
Ischaemic heart disease
Heart failure
Diabetes
Obesity
Thyrotoxicosis
Excess alcohol
Infection
  • The precise underlying mechanisms are unclear however factors including Renin-Angiotensin-Aldosterone-System (RAAS) activation, structural changes to the atria and rapid activation of the atria secondary to other supraventricular tachyarrhythmias are thought to be involved.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Diagnosis

A

Careful clinical assessment and evaluation of the patient is required. AF is often initially diagnosed in the GP surgery when the patient’s pulse reveals an irregular heartbeat. Not all irregular pulses lead to a diagnosis of AF. AF is confirmed with a 12 lead ECG. A 24 hour ambulatory ECG monitor is used in patients with suspected paroxysmal AF. Transthoracic echocardiogram is also performed when, for example, a rhythm control strategy is being considered or where structural heart abnormalities are suspected.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Symptoms

A

Many patients are asymptomatic which is why AF can remain undetected. It is also why prevalence of AF in the population is thought to be underestimated.

Symptoms experienced by the patient may include the following:

Shortness of breath
Palpitations
Chest pain
Dizziness / feeling faint
Tiredness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Classification

A

Once diagnosed AF is classified according to timing of onset

  • Lone AF
  • Paroxysmal
  • Persistent
  • Permanent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Clinical features and arrhythmia pattern - lone AF

A

A single episode of AF where the heart is structurally normal and there is normal clinical examination.

Lone AF may or may not recur.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Clinical features and arrhythmia pattern - Paroxysmal

A

The pattern is recurrent. The AF terminates spontaneously usually within 7 days, but often within 24-48 hours.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Clinical features and arrhythmia pattern - Persistent

A

The pattern is recurrent. The AF lasts more than 7 days and does not self-terminate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Clinical features and arrhythmia pattern - Permanent

A

The pattern is established. The AF is not terminated. Cardioversion has either failed or has not been attempted. Duration is greater than 1 year.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Management

A

Early diagnosis and treatment of any underlying / predisposing factors.
A risk assessment of the likelihood of developing a thromboembolism is required along with the need for thromboprophylaxis. (See section on Stroke prevention).
The need for either a rate or a rhythm control strategy should then be considered.
Patients should also be offered a personalised package of care to include up-to-date education and information on such facts as stroke awareness and prevention, rate control and assessment of symptoms for rhythm control. Patients should also know who to contact for advice and for psychological support if needed. Pharmacists can make an important contribution in providing education and advice on medicines to patients with AF.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Summary of options for rhythm control strategy are as follows:

A
  • Cardioversion
  • Amiodarone can be considered starting 4 weeks before cardioversion and continuing for up to 12 months in order to maintain sinus rhythm. However the benefits and risks of using amiodarone should be discussed with the patient first.
  • Drug treatment for long term rhythm control. These include standard beta blockers (not sotalol) as first line treatment and other anti-arrhythmic agents such as dronedarone and amiodarone.
  • Left atrial ablation. This can be used when drug therapy fails to control symptoms or is unsuitable.
  • Pace and ablate strategy. This can be considered in patients with permanent AF and symptoms or with left ventricular dysfunction thought to be caused by high ventricular rates.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Non-Pharmacological management

A

Up to 50% of patients with recent onset AF will revert to normal sinus rhythm spontaneously.

In order to convert to normal sinus rhythm either pharmacological or electrical cardioversion is considered. Electrical cardioversion is often quicker and has a high success rate but the procedure requires the need for ‘conscious sedation’ or for anaesthesia.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Pharmacological management

A

When approaching pharmacological management a choice should first be made between either rate or rhythm control for each individual patient.

Rate control strategy

The aim is to control the ventricular rate (= rate control) promptly. Drug therapy lies between a beta blocker (not sotalol) or a ‘rate-limiting’ calcium channel blocker.

Rate control can be used first line for most patients presenting with AF.

NICE recommends that rate control is ‘offered as the first line strategy’ for patients presenting with AF except in the following:

whose AF has a reversible cause
who have heart failure primarily thought to be caused by AF
who present with new-onset AF
with atrial flutter where ablation strategy is considered suitable to restore sinus rhythm
when clinical judgement considers a rhythm control strategy would be more suitable

Rhythm control strategy

Rhythm control aims to restore and maintain normal sinus rhythm. This can be achieved by using either an anti-arrhythmic agent (= pharmacological therapy) and/or electrical rhythm control (= cardioversion). This strategy is used for patients whose symptoms continue after heart rate has been controlled OR in whom rate control has failed.

NICE recommends that rhythm control strategy may be more appropriate in the following cases i.e. for patients in whom rate control is not recommended:

With new onset AF
Where AF has a reversible cause e.g. infection
Where AF is thought to be caused or worsened by heart failure
With atrial flutter where ablation strategy is considered suitable to restore sinus rhythm
When clinical judgement considers a rhythm control strategy more suitable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

‘Pill-in-the-pocket’ Strategy

A

This strategy is suitable for patients who have paroxysmal AF and who have a history of infrequent symptomatic episodes. They should also have a systolic BP of greater than 100mmHg and a resting heart rate of greater than 70bpm. A history of left ventricular dysfunction, valvular or ischaemic cardiac disease should be ruled out.

Patients should be able to fully understand when and how to take their medication in the event of a paroxysm of AF. Drugs such as flecainide or propafenone are used on a ‘when required’ basis. Known precipitants such as caffeine, alcohol and stress should be avoided where possible.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Stroke prevention

A

AF is an independent risk factor for the development of stroke and thromboembolism. It is estimated that the risk of developing a stroke is five times higher in patients who have AF. The disorganised electrical conduction in the atria leads to the risk of blood becoming static in the atria and the potential for a thrombus to form. Subsequently there is a risk of a clot entering the circulation and causing a stroke. Patients with AF are at an increased risk of both mortality and morbidity arising from stroke development (refer to Topic on Stroke).

According to NICE all patients presenting with AF (whether symptomatic or asymptomatic) should be assessed for stroke risk using the CHA2DS2-VASc stroke risk score. Patients with a score of 2 or greater should be offered anticoagulation, taking risk of bleeding into account.

Patients require assessment for the risk of developing bleeding prior to or if they have already started anticoagulants. The HASBLED scoring system is used to identify patients likely to be at risk and indicates whether anticoagulation is safe to use. Identification and correction of any underlying risk factors for bleeding, for example uncontrolled hypertension or concurrent medication such as NSAIDs, should be undertaken.

Anticoagulation

Options for anticoagulation management should be discussed with the patient. Choice should be based on the patient’s clinical features and on the patient’s own preference. Successful stroke prevention requires good anticoagulant control and appropriate drug therapy monitoring. Either an older established oral anticoagulant such as a vitamin K antagonist or a newer oral anticoagulant (NOAC) may be offered provided they are licensed for stroke prevention in non-valvular AF. Examples of oral anticoagulants are:

Vitamin K antagonists e.g. warfarin
Direct thrombin inhibitors, e.g. dabigatran (NOAC)
Direct inhibitor of activated factor X (factor Xa), e.g. apixaban, rivaroxaban.

NOTE: Aspirin (an antiplatelet agent) is no longer offered as monotherapy for stroke prevention in patients with AF since this strategy is now considered insufficiently effective.

17
Q

Use the CHA2DS2-VASc stroke risk score to assess stroke risk in people with any of the following:

A

symptomatic or asymptomatic paroxysmal, persistent or permanent atrial fibrillation

atrial flutter

a continuing risk of arrhythmia recurrence after cardioversion back to sinus rhythm.

18
Q

Use the HAS-BLED score to assess the risk of bleeding in people who are starting or have started anticoagulation. Offer modification and monitoring of the following risk factors:

A

uncontrolled hypertension

poor control of international normalised ratio (INR) (‘labile INRs’)

concurrent medication, for example concomitant use of aspirin or a non‑steroidal anti‑inflammatory drug (NSAID)

harmful alcohol consumption

19
Q

Anticoagulation

A

Anticoagulation may be with apixaban, dabigatran etexilate, rivaroxaban or a vitamin K antagonist.

Offer anticoagulation to people with a CHA2DS2-VASc score of 2 or above, taking bleeding risk into account.

20
Q

When should aspirin not be offered

A

Do not offer aspirin monotherapy solely for stroke prevention to people with atrial fibrillation.

21
Q

When to offer rate or rhythm control

A

Offer rate control as the first‑line strategy to people with atrial fibrillation, except in people:

whose atrial fibrillation has a reversible cause

who have heart failure thought to be primarily caused by atrial fibrillation

with new‑onset atrial fibrillation

with atrial flutter whose condition is considered suitable for an ablation strategy to restore sinus rhythm

for whom a rhythm control strategy would be more suitable based on clinical judgement.

22
Q

Left atrial ablation and a pace and ablate strategy

A

f drug treatment has failed to control symptoms of atrial fibrillation or is unsuitable:

offer left atrial catheter ablation to people with paroxysmal atrial fibrillation

consider left atrial catheter or surgical ablation for people with persistent atrial fibrillation

discuss the risks and benefits with the person

23
Q

Which drug is the most appropriate choice for rate control management of atrial fibrillation?

A

atenolol

24
Q

Which drug is the most appropriate choice to use for management of atrial fibrillation using the pill-in-the-pocket strategy?

A

flecainide or propafenone

25
Q

European society of cardiology guidance for acute management of AF

A

Recent-onset atrial fibrillation (<48h) –> haemodynamic instability

–> yes (electrical cardioversion

–> no –> structural heart disease –> yes (amiodarone IV)

–> no (flecainide IV, propafenone IV, ibutilide IV)

26
Q

Rate limiting CCB

A

Verapamil or Diltiazem

27
Q

CHADS score

A
Chronic heart failure (1)
Hypertension (1)
Age >75 years (1)
Diabetes mellitus (1)
Stroke or TIA (2)

CHADS score >2 initiate anticoagulant therapy with either warfarin or DOAC (dabigatran, apixaban, rivorixaban)