QuestionSBA
QuestionChoice
This would be appropriate for symptomatic control of paroxysmal atrial fibrillation, when patients are aware of the arrhythmia occurring.
10015712
b
PRN flecanide
QuestionChoice
The patient's CHA2DS2-VASc score is 4. The BNF advises Edoxaban be used with caution in moderate to severe mitral stenosis as the safety and efficacy of the medication has not been established.
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Edoxaban
QuestionChoice
There is no indication for cardioversion. The patient is haemodynamically stable, and cardioversion is unlikely to resolve valvular AF
10015713
c
DC cardioversion
QuestionChoice
Surgical intervention is only required when mitral stenosis is severe or symptomatic. In this case, it is moderate.
10015715
e
Mitral comissurotomy
QuestionChoice
The patient's CHA2DS2-VASc score is 4 due to a history of TIA (2 points), hypertension (1 point) and age 65-74 years (1 point). The BNF advises that Edoxaban be prescribed with caution in patients with moderate to severe mitral stenosis, making warfarin the most appropriate anticoagulant of choice here.
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Warfarin
QuestionComment
I thought the valvular disease might cause the AF and we treat cause before symptoms? 
38646
QuestionComment
Don't think fixing the mitral stenosis always fixes the underlying AF (maybe due to the remodelling which has occurred due to constant high atrial pressure). Even after intervention its likely he will have an ongoing need for anticoagulation even if his AF is fixed.
40907
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subscriber
;-;
User
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Hallux Ketone
QuestionComment
didn't realise this was the psa
61974
User
subscriber
Positive Whiff Test
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# Summary 

Atrial fibrillation (AF) is the most common arrhythmia characterised by irregular and uncoordinated atrial contraction at a rate of 300-600 beats per minute. Its prevalence increases with age, and it can be caused by various cardiac and non-cardiac factors. Symptoms of AF include palpitations, chest pain, shortness of breath, lightheadedness, and syncope. Diagnosis is confirmed by an ECG showing the absence of p waves and an irregularly irregular rhythm. Management depends on the acute or chronic nature of the AF and involves rate or rhythm control strategies. Anticoagulation is essential to mitigate the risk of stroke in chronic AF. Complications include heart failure, embolism, and bleeding. With appropriate management, AF has a favourable prognosis.

# Definition 

Atrial fibrillation (AF) is characterised by irregular, uncoordinated atrial contraction usually at a rate of 300-600 beats per minute. Delay at the AVN means that only some of the atrial impulses are conducted to the ventricles, resulting in an irregular ventricular response.

# Epidemiology 

AF is the commonest sustained cardiac arrhythmia. The prevalence of AF roughly doubles with each advancing decade of age, from 0.5% at age 50 years to almost 9% at age 80 years.

# Pathophysiology

The exact pathophysiology of AF is unclear, but factors that cause atrial dilatation through inflammation and fibrosis leads to disorganised electrical impulses (which originate near the pulmonary veins) that overwhelm the SAN. These disorganised electrical impulses are usually at a rate of 300-600 beats per minute and are intermittently conducted through the AVN leading to irregular activation of the ventricles. 

# Classification 

* Acute: lasts <48 hours
* Paroxysmal: lasts <7 days and is intermittent
* Persistent: lasts >7 days but is amenable to cardioversion
* Permanent: lasts >7 days and is not amenable to cardioversion

Atrial fibrillation can also be classified as to whether it is 'fast' or 'slow'. Fast AF refers to AF that is at a rate of =>100bpm. Slow AF refers to AF that is at a rate of <=60bpm. 

# Causes 

Cardiac:

* Ischaemic heart disease: most common cause in the UK. 
* Hypertension
* Rheumatic heart disease (typically affecting the mitral valve): most common cause in less developed countries.
* Peri-/myocarditis

Non-cardiac:

* Dehydration
* Endocrine causes e.g. hyperthyroidism
* Infective causes e.g. sepsis 
* Pulmonary causes e.g. pneumonia or pulmonary embolism
* Environmental toxins e.g. alcohol abuse
* Electrolyte disturbances e.g. hypokalaemia, hypomagnesaemia 

# Symptoms

* Palpitations
* Chest pain
* Shortness of breath
* Lightheadedness
* Syncope

# Signs

* Irregularly irregular pulse rate with a variable volume pulse.
* A single waveform on the jugular venous pressure (due to loss of the a wave - this normally represents atrial contraction).
* An apical to radial pulse deficit (as not all atrial impulses are mechanically conducted to the ventricles).
* On auscultation there may be a variable intensity first heart sound.
* Features suggestive of the underlying cause e.g. hyperthyroidism, alcohol excess, sepsis
* Features suggestive of complications resulting from the AF e.g. heart failure.

# Differential Diagnoses 

Important differentials for atrial fibrillation include other common causes of narrow and broad complex tachycardias. Tachycardias may present with palpitations, shortness of breath, and dyspnoea. 

* **Atrial Flutter** 
	* **Similarities**: atrial flutter may have a regular peripheral pulse or may be irregularly irregular if the flutter has variable block. Atrial fibrillation leads to an irregularly irregular peripheral pulse on palpation.
	* **Differences**: distinguishing between the two requires an ECG. Atrial fibrillation on ECG shows a fibrillating baseline with no visible p waves. Atrial flutter characteristically has a sawtooth baseline. 

* **Supraventricular Tachycardia**
	* **Similarities**: atrial flutter is a type of SVT, and other types including AVNRT and AVRT may present identically. 
	* **Differences**: distinguishing between different types of SVT requires an ECG. 

* **Ventricular Tachycardia**
	* **Similarities**:both may present similarly. 
	* **Differences**: the ECG patterns differ tremendously.  

For palpitation histories, it is also important to consider whether the presentation is being driven by anxiety. However, it is important as a rule of thumb to rule out organic causes first. 

# Investigations

## Bedside

**Definitive diagnosis: 12-lead ECG** shows absence of p waves with an irregularly irregular rhythmn. 

[lightgallery]

- If a person has a suspected diagnosis of paroxysmal AF which is not detected on standard ECG, arrange ambulatory electrocardiography or cardiology referral, depending on the frequency and duration of symptoms and local referral pathways

## Bloods 

Routine bloods: to look for reversible causes including infection (raised WCC or CRP), hyperthyroidism (raised T3/T4) or alcohol use (raised MCV and GGT).

## Imaging

Echocardiogram: can be used to see if there is a cardiac cause of the AF e.g. left atrial dilatation secondary to mitral valve disease. 

# Management

Consider emergency admission or Cardiology referral if a patient presents with:

- New-onset AF within the past 48 hours and is haemodynamically unstable
- Severe symptoms of AF due to rapid (bpm > 150 ) or very slow (bpm < 40) ventricular rate
- Concomitant acute decompensated heart failure
- Complications of AF, such as TIA/stroke
- An acute, potentially reversible trigger such as pneumonia/sepsis or thyrotoxicosis

If they do not require acute management or emergency admission, they can be considered for anticoagulation and rate-control treatment in primary care.

## Management of Acute or New-onset Atrial Fibrillation

For emergencies, always follow an A-E structure. Identify reversible causes (dyselectrolytaemias, drugs, cardiac causes etc.) 

*If there are adverse signs (e.g. shock, syncope, heart failure, myocardial ischaemia):* 

* **1st line** = **synchronised DC cardioversion +/- amiodarone.**

*If there are no adverse signs:* and the rhythm is irregular it is likely atrial fibrillation. 

* **If the patient is stable and onset of AF <48 hours**: 
	* Rate or rhythmn control.
	* Rhythm control with DC cardioversion (+ sedation) or pharmacological anti-arrhythmics (fleicanide if no structural heart disease, amiodarone if history of structural heart disease). 
	* If DC cardioversion is delayed then heparin will be required to anticoagulate the patient. 

* **If the patient is stable and onset of AF >48 hours/unclear time of onset**: 
	* Rate control only. 
	* Rate control with beta-blockers, diltiazem or digoxin. 
	* Need to anticoagulate for 3/52 prior to attempting cardioversion due to the risk of throwing off a clot. You can also perform a TOE to exclude a mural thrombus. 

If AF persists or reversible causes are not present then decisions should be made about rate control, rhythm control or electrical cardioversion.

## Management of Chronic AF 

The cornerstones of managing chronic AF are related to symptom control and mitigating stroke risk. 

## Symptom Management of Chronic AF 

### Rate vs. Rhythm Control 

#### Rate-Control

The aim of rate control is to reduce a patient's heart rate in order to reduce symptoms.
 
* First line in most patients. See below for patients who should undergo rhythm control. 
*  **1st line medications:** beta-blocker (bisoprolol) or rate-limiting calcium channel blocker (diltiazem). 
*  **2nd line medications**: dual therapy (under specialist guidance) 
*  Digoxin monotherapy may be considered in those with non-paroxysmal AF who are sedentary. 
 
#### Rhythm Control

The aim of rhythm control is to revert a patient back into sinus rhythm. 
 
Rhythm control should be offered to patients who have: 

* AF secondary to a reversible cause
* Heart failure thought to be caused by AF
* New-onset AF
* Or those for whom a rhythm control strategy would be more suitable based on clinical judgement. 

Rhythm control can be achieved via two methods:

* Electrical cardioversion
* Pharmacological cardioversion: amiodarone, fleicanide or sotalol. 

The moment of return to sinus rhythm poses the highest stroke risk. Therefore, rhythm control should only be attempted if the onset of AF <48 hours, a patient has undergone 3/52 of anticoagulation or has had a TOE to exclude a mural thrombus. 

Note that patients in chronic AF or those who have failed cardioversion before are unlikely to be successfully cardioverted so this would not be considered in most of these cases.

#### Catheter Ablation 

A final option for rhythm control is catheter ablation of the arrhythmogenic focus between the pulmonary veins and left atrium. Even if teh foci is ablated, this does not reduce stroke risk and the patient must be anticoagulated. There is a high risk of recurrence (50% have recurrent AF). 

## Medications used for Rate Control  

### Beta-blockers

* The most commonly used beta-blocker in AF is bisoprolol.
* Commonly used medication for acute treatment and chronic management.
* Technically it is contraindicated in COPD and asthma (in reality unless the conditions are considered _brittle_ it is not a problem). 
* Cannot be used in hypotension because it will drop blood pressure.
* Note that sotalol CANNOT be used as a rate control agent because of its rhythm control action.

### Non-dihydropyridine calcium channel blockers

* Calcium channel blockers used in AF are diltiazem or verapamil.
* They are not frequently used in hospital settings because they are negatively ionotropic and therefore they are contraindicated in heart failure.

### Digoxin

* Usual for patients who are hypotensive or who have co-existent heart failure.
* Should be avoided in younger patients because it increases cardiac mortality.
* Often used second-line in conjunction with beta-blockers if fast AF remains refractory.

## Medications used for Rhythm Control

* Flecainide
  * Can be either given regularly or as a "pill in the pocket" when symptoms come on.
  * Is preferred in _young patients_ who have _structurally normal hearts_ because it can induce fatal arrhythmias in those with structural heart disease.

* Amiodarone
  * Extremely effective drug in controlling both rate and rhythm.
  * However it comes with a massive list of significant side-effects so should normally only be given to _older, sedentary patients_.

* Sotalol
  * This is a beta blocker with additional K channel blocker action.
  * Used for those that don't meet the demographics for either flecainide or amiodarone.

## Mitigating Stroke Risk in Chronic AF 

In atrial fibrillation, the lack of organised atrial contraction can lead to blood stasis in the left atrium. Due to the left atrial appendage, blood clots easily here and if part of this clot embolises it can lead to a stroke. Therefore, if a patient has any history of atrial fibrillation or atrial flutter the need for anticoagulation must be considered. 

Patients need to be considered according to their stroke risk (CHADS2VASc score) and their bleeding risk (ORBIT score) to determine whether anticoagulation is appropriate. 

### CHADS2VASc Score

Patients should be risk stratified using the CHADS2VASc score:

* C: 1 point for congestive cardiac failure.
* H: 1 point for hypertension.
* A2: 2 points if the patient is aged 75 or over.
* D: 1 point if the patient has diabetes mellitus.
* S2: 2 points if the patient has previously had a stroke or transient ischaemic attack (TIA).
* V: 1 point if the patient has known vascular disease.
* A: 1 point if the patient is aged 65-74.
* Sc: 1 point if the patient is female.

#### Interpretation of the CHADS2VASc score

The minimum score is 0 (associated with 0% annual stroke risk) and maximum score is 9 (15% annual stroke risk).
Males who score 1 or more or females who score 2 or more should be anticoagulated (as long as the risk of stroke outweighs the risk of bleeding). 

#### ORBIT Score

Risks of anticoagulation also need to be considered. Historically the HASBLED score stratified bleeding risk:

* H: Hypertension 1 point
* A: Abnormal renal or liver function 2 points if both are present
* S: Stroke (previous) 1 point
* B: Major bleed (previous) 1 point
* L: Labile INR 1 point
* E: Elderly (>65) 1 point
* D: Drugs/alcohol 1 point for drug or alcohol use (2 points if both are present)

In their 2021 AF guidelines NICE suggested the use of the ORBIT score which takes into account:

* Sex
* Haemoglobin (<13mg/Dl in males, <12mg<dL in females) 2 points
* Age (>74) 1 point
* Bleeding history 2 points
* Renal function (eGFR <60) 1 point
* Concomitant use of anti-platelets 1 point

#### Interpretation of the HASBLED and ORBIT scores

In reality very little guidance exists about how to weigh up the stroke and bleeding risks when making a decision on anticoagulation. Choice of long term anticoagulation is generally  a decision led by patient choice and clinical judgement.

### Anticoagulation options in AF

* **Direct oral anticoagulants (DOACs)**:
  * Considered first line for anticoagulation in AF. 
  * Examples of DOACs are edoxaban, apixaban, rivaroxaban & dabigatran
  * **Do not** require monitoring
  * Generally associated with fewer bleeding risks compared to warfarin.
  * Most have approximately 12 hour half-lives therefore if a patient misses a dose they are not covered.

* **Warfarin**:
  * Requires cover with LMWH for 5 days when initiating treatment (because warfarin is initially _prothrombotic_).
  * Requires regular INR monitoring.
  * INR can be affected by a whole host of drugs and foods.
  * Has 40 hour half-life therefore anticoagulant effect lasts days.
  * Is the only oral anticoagulant licenced for **valvular AF**.
* **Low Molecular Weight Heparin (LMWH)**:
  * An example of a LMWH is enoxaparin.
  * A rare option in patients who cannot tolerate oral treatment.
  * Involves daily _treatment dose_ injections.

# Complications

Most complications are either from uncontrolled heart rate, embolism or from anticoagulation. They include:

* Heart failure
* Systemic emboli:
  * Ischaemic Stroke
  * Mesenteric ischaemia
  * Acute limb ischaemia
* Bleeding:
  * GI
  * Intracranial
  
# Prognosis 

If patients are anticoagulated and are on either rhythm or rate control AF can remain a benign cardiac arrhythmia. 

# NICE Guidelines

[Click here to see information on NICE CKS guidance for AF](https://cks.nice.org.uk/topics/atrial-fibrillation/)

# References
 
[Live Life in the Fast Lane AF ECG Summary](https://litfl.com/atrial-fibrillation-ecg-library/)
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An ECG showing an irregularly irregular heart rate and absent p waves, these are characteristic signs of atrial fibrillation.
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Patients with atrial fibrillation, a history of Transient Ischaemic Attack (TIA) or stroke, hypertension, and age over 65 years are often considered for anticoagulation to reduce the risk of thromboembolic events.
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A 67 year old man is noted to have an irregularly irregular pulse during a routine examination. His medical history is significant for hypertension and a previous TIA. His GFR is >90.

Observations:

* Heart rate: 73 beats per minute

* Blood pressure: 134/85 mmHg

* Temperature: 36.9 degrees

Investigations:

* ECG: No discernible P waves

* Echocardiogram: Moderate mitral stenosis

What is the most appropriate next step in management?
a