Atrial fibrillation (AF) refers to a characteristic disordered pattern of contraction in the atria, associated with mortality and morbidity. Atrial fibrillation is one of the most common arrhythmias in the UK and is associated with a high risk of ischaemic stroke without treatment.

AF requires prompt treatment whenever it is found, with the aim of controlling both symptoms, which range from mild to life-threatening, and the risk of stroke. As AF can be the result of multiple pathological processes in the cardiovascular system it should also be regarded as a non-specific sign of further underlying cardiovascular dysfunction until proven otherwise.

Major guidelines to be aware of when formulating a treatment plan for patients with AF include the 2014 National Institute of Health and Care Excellence (NICE) guidelines and 2020 clinical knowledge summary article (CKS), the 2014 joint American College of Cardiology/American Heart Association/Heart Rhythm Society (ACC/AHA/HRS) guidelines and 2016 European Society of Cardiology guidelines. While local guidelines should always take precedence over their national and international counterparts it is helpful to be familiar with these texts. These national and international guidelines form the basis of a majority of local guidelines, and will be used extensively in this guide to provide an overview of the treatment of this condition.


Atrial fibrillation (AF) is classified based on the how often a patient is in AF, compared to how often they are in sinus rhythm.

  • A patient with persistent AF is one who experiences AF at all times
    • This is defined by the AHA/ACC/HRS guidelines (2014) as ‘continuous AF that is sustained for more than 7 days’
    • These guidelines also note that some patients in this group can be described as having permanent AF, where a return to sinus rhythm is no longer part of their treatment plan
  • A patient with paroxysmal AF only experiences AF at certain times. At all other times their heart contracts in sinus rhythm
    • This is defined by the AHA/ACC/HRS guidelines (2014) as ‘AF that terminates spontaneously within 7 days of onset’
    • Most patients in this group have multiple short episodes of AF which may or may not have an obvious trigger
    • Paroxysmal AF can progress to persistent AF over the course of many years. The AHA/ACC/HRS guidelines (2014) note that episodes of paroxysmal AF occur more often and for a longer duration as the condition progresses
  • Neither of the above definitions are based on symptoms. Both of the above patient groups can be asymptomatic
  • Both persistent and paroxysmal AF patients have a high risk of stroke, and both should be considered one common entity with respect to the calculation of stroke risk


  • Incidence: 700.00 cases per 100,000 person-years
  • Peak incidence: 70+ years
  • Sex ratio: more common in males 1.2:1
Condition Relative
Atrial fibrillation1
Supraventricular tachycardia0.05
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+


In this section we will aim to list some of the many underlying risk factors, whether they be disease processes or lifestyle processes, which contribute to AF. In order to compile a reasonable list a number of sources have been used, which are listed below, but include review articles, guidelines and textbooks.

As noted by Andrade et al. (2014), it is important to understand that AF is most often the result of an underlying risk modifying process, and it is rare for it to occur without the presence of risk factors or in an electrically normal heart. There are multiple pathways via which risk factors can result in AF but some common pathways described by the AHA/ACC/HRS guidelines (2014) include structural remodelling of and changes to the properties of action potentials within the atria. In addition to these processes, the AHA/ACC/HRS (2014) also note that some presentations of AF, collectively called Lone AF, can also be idiopathic.

The major risk factors to be aware of for AF are listed below. Unless noted otherwise, these risk factors are derived from the AHA/ACC/HRS guidelines (2014):

  • Risk factors affecting cardiovascular system: these diseases and lifestyle factors can result in AF via changes to the heart. Kumar and Clark (2017) note that a wide variety of changes in the atria can contribute to AF, including irritation, inflammation, high pressure or hypertrophy of the atria, by creating conditions where aberrations in the conduction of electrical signals in the heart are more likely to occur. They include:
    • Hypertension, which according to Andrade et al. (2014) results in a moderate risk increase
    • Ischaemic Heart Disease, according to Shah and Kantharia (n.d.)
    • Heart Failure, including due to valvular disease which, according to Andrade et al (2014) results in an especially large risk increase
    • Cardiomyopathy, according to Andrade et al. (2014)
    • Cardiothoracic surgery
    • Diabetes Mellitus
    • Obesity

  • Risk factors affecting the respiratory system:these diseases and lifestyle factors can also result in structural changes to the heart. Processes behind this include, but are not limited to, increased pulmonary arterial pressure and increased cardiac demand during states of respiratory distress. They include:
    • Pneumonia
    • Smoking
    • Obstructive Sleep Apnoea

  • Other modifiable risk factors: these diseases can contribute to AF via their affect on the autonomic nervous system or via other mechanisms. The autonomic nervous system is notable as it plays a key role in the control of heart chronotropy and inotropy. They include:
    • Thyrotoxicosis
    • Caffeine, according to Shah and Kantharia (n.d.)
    • Alcohol excess
    • Chronic kidney disease, according to Andrade et al. (2014)

  • Non-modifiable risk factors to be aware of include:
    • Increasing age, according to Andrade et al. (2014) the risk of AF doubles with each decade of life
    • Male sex, according to Shah and Kantharia (n.d.). Andrade et al. (2014) note that males are 1.5 times more likely to develop AF than in females
    • Inherited risk factors, according to Andrade et al. (2014)

It is important to be aware of the fact that acute exacerbations of the above risk factors, especially acute respiratory diseases like infective pneumonia, can act as triggers for symptomatic AF. The management of these risk factors, including the modification of lifestyle factors, can be of benefit in the overall management of AF.


All myocytes in the heart have the potential to contract independently and pace themselves , however the heart requires synchronous contraction in order to pump blood in a manner that supports life.

During everyday function the sinoatrial node (SAN) takes the role of the chief pacemaker of the heart and is responsible for the synchronised contraction of both atria. The regular depolarisation and repolarisation of the SAN results in waves of depolarisation that spread across the atria. This results in synchronised myocyte contraction which forces blood into the ventricles due to excitation-contraction coupling.

During episodes of atrial fibrillation myocytes in the atria contract largely independently of each other and in an unsynchronised pattern, leading to the macroscopic appearance of ‘fibrillation’, referring to the fast vibration of the cardiac tissue. The underlying electrical activity in the heart at this time is disordered, with multiple groups of myocytes depolarising independently of the SAN and each other. Various pathological processes can contribute to an electrical environment in the heart where this is likely to occur. These are discussed in more detail in the aetiology section but can generally be thought to include:
  • Risk factors affecting the cardiovascular system
  • Risk factors affecting the respiratory system
  • Non-modifiable risk factors
  • Modifiable risk factors

Atrial fibrillation does not result in fibrillation of the ventricles, which is a rhythm incompatible with life, due to the action of the atrioventricular node (AVN). The AVN is the only path through which action potentials in the atria can affect the ventricles. The time between depolarisations of the AVN is slow due to a long refractory repolarisation phase during which it cannot depolarise again, regardless of the frequency of stimulation from the atria. As a result multiple action potentials from multiple groups of myocytes in the atria are reduced to single impulses from one point by the AVN, meaning the synchronised contraction of the ventricles can continue, regardless of the presence of AF. This synchronised contraction means the ventricles remain efficient in pumping blood around the body, even when the atria are in fibrillation. However, as the AVN is being stimulated randomly by the atria, rather than regularly, the contraction of the ventricles is therefore irregularly spaced apart despite being electrically normal.

Patients with AF can present with life threatening, mild or no symptoms. Asymptomatic patients do not notice the presence of AF as the gross function of the heart at rest may not affected in a major way by its presence. Symptomatic patients may notice the irregularity of their heartbeat and present with palpitations, particularly as these beats can vary in their force and volume. This variation occurs because the combination of the loss of co-ordinated atrial contraction and the irregular timing of ventricular contraction mean that the stroke volume of the ventricles heavily depends on how long the ventricles have in-between these irregular contractions to fill.

Patients with AF may develop life threatening symptoms for a variety of reasons. The pathophysiology of chronic heart failure and haemodynamic instability in AF are described in short in the 2014 AHA/ACC/HRS guidelines, but an in depth appreciation of these mechanisms is best gained from review papers such as those mentioned below. Andrade et al. (2014), for example, note that AF can result from, result in and worsen chronic heart failure while also mentioning that the presence of AF is known to impact cardiac output because of the loss of function of the atria . It is also known that tachycardia in the presence of AF can lead to haemodynamic instability. As described by Arrigo et al. (2014), severe tachycardia in the presence of AF reduces the space of time between ventricular beats to the extent that the ventricles do not fill properly. The result is that stroke volume falls and cardiac output lowers to the extent that acute symptoms develop. While the dangers of acute tachycardia in AF may be common knowledge among physicians, as noted by Andrade et al. chronic tachycardias in patients with AF can lead to chronic heart failure by causing a cardiomyopathy.

As discussed earlier AF can also cause a number of embolic complications. As described in the 2014 ACC/AHA/HRS guidelines, the loss of co-ordinated atrial contraction can mean that blood can pool in the atria and form clots, particularly in the left atrial appendage. These clots can go on to enter the ventricles and then the systemic circulation where they can occlude vessels, causing strokes and other ischaemic lesions.

Clinical features

AF is a condition with a wide spectrum of clinical features. Patients with AF can be asymptomatic or may have severe or even life-threatening symptoms. In addition, AF can also cause numerous embolic complications, which can themselves cause patients to present to primary or secondary care. The most common clinical presentations to be aware of are patients with asymptomatic AF, AF with non life-threatening symptoms, AF presenting with complications and AF presenting with haemodynamic instability/compromise.

Asymptomatic AF

Patients with AF who are asymptomatic can remain undiagnosed for a long time, and may only be found when they develop serious complications or symptoms. AF in this form is extremely common, with up to 35% of those with AF being unaware of its presence, according to Andrade et al (2014). As asymptomatic AF has the potential to cause harm, our approach should be to attempt to diagnose it before serious symptoms appear.

Patients who exhibit risk factors for AF should always be screened by palpation of the radial pulse, which in AF is irregularly irregular. Patients with an irregularly irregular pulse should then have their diagnosis confirmed and treatment initiated.

Irregularly irregular pulse: this refers to a heart rhythm where heartbeats follow each other in an entirely random pattern, and is a characteristic sign of AF.

While the presence of risk factors may already be apparent from the past medical history of a patient or due to the presentation of the patient if they are already in hospital, it is important to take a full history and examination to identify undiagnosed risks. A list of risk factors to consider can be found in the aetiology section.

AF with non-life threatening symptoms

Patients with AF who are symptomatic most often present with a complaint of palpitations. The key secondary symptom identified in the 2014 AHA/ACC/HRS guidelines is fatigue.

Presentations of AF can vary with respect to how often these symptoms occur, how long they occur for and triggering and alleviating factors. It is recommended in the AHA/ACC/HRS guidelines (2014) that physicians attempt to elicit this information to aid with further management.

The symptoms of AF can become more severe as the heart rate increases, and may become life threatening with haemodynamic instability at high heart rates, or in those with underlying disease. The term ‘fast AF’ refers to patients with AF who have a high heart rate, these patients often require more urgent assessment and management due to the risk their high heart rate poses.

AF presenting with complications

A significant proportion of patients may present with the complications of AF, with or without a pre-existing diagnosis of AF. These complications include ischaemic stroke, mesenteric ischaemia and acute limb ischaemia, all of which are due to the formation of emboli in the heart.

Patients who have AF should always be asked if they are experiencing symptoms that can be due to these complications. Neurological exams can also be employed in patients in whom a stroke is suspected. Patients who present with disease that could be of embolic origin should likewise be screened for AF, as it is one of the most common causes of embolic phenomena.

The pathophysiology of these complications will be discussed in the pathophysiology section.

AF presenting with haemodynamic instability

The most serious symptoms associated with AF in the absence of complications are those where the presence of AF causes some form of circulatory failure, referred to as haemodynamic instability in 2014 NICE guidelines. This is known to occur in patients with high heart rates, and in those with underlying disease. This can manifest with:

  • Acute heart failure, causing:
  • Cardiogenic shock, the signs of which are:
  • Syncope or pre-syncope
  • Cardiac chest pain, including myocardial infarction
    • This is most common in patients with some level of pre-existing coronary heart disease

Signs of haemodynamic compromise in AF according to NICE CKS (2020)
Heart Rate >150 bpm
Blood Pressure <90 mmHg
Syncope or severe dizziness
Shortness of breath
Chest Pain

Patients presenting with these symptoms require immediate emergency treatment in a secondary care facility.


The prognosis of AF is widely variable and can change based on factors such as age, frailty, the presence of co-morbidities and the severity of initial and continuing symptoms. Embolic complications, if they arise, often result high morbidity and mortality and a negative prognosis.


2014 NICE and AHA/ACC/HRS guidelines suggest that patients should undergo a sequence of screening and confirmatory investigations in order to be formally diagnosed with AF. These investigations include:

  • Assessment of the radial pulse, which is the main screening investigation used in AF throughout primary and secondary care.
    • Indication: NICE guidelines (2014) suggest that this investigation should be used when AF is suspected in a symptomatic patient or in a patient with risk factors or possible complications of AF
    • Advantages: sensitive and quick to perform at the bedside
    • Disadvantages: palpation is dependent on the experience of the clinician and will miss the presence of paroxysmal AF in between episodes
    • Variations: any pulse, e.g. brachial, femoral or carotid, can be used in this test. If the pulses prove difficult to find, a doppler machine or auscultation of the heart can be used to listen for an irregular beat
    • Key findings: an irregularly irregular pulse is a finding which suggests the presence of AF
    • Follow-up: NICE guidelines (2014) state that suggestive findings must be followed up with an immediate ECG to confirm the diagnosis. A regular pulse does not rule out AF. Consider ECG monitoring when a regular pulse is present, especially when an intermittent pattern of symptoms is described by the patient, which can imply paroxysmal AF. Tailor ECG monitoring such that it is likely to catch these patients during their symptoms

  • ECG monitoring is the major confirmatory investigation used in AF. ECGs can also provide key information about underlying risk factors for AF to physicians
    • Indication: NICE guidelines (2014) suggest that this investigation should be used in patients with an irregularly irregular pulse and in patients with suspected AF where the pulse is normal, as long as clinical suspicion remains
    • Advantages: readily available in primary and secondary care. Can confirm the presence of AF in most patients. Can provide additional information about heart structure. Findings can be read by multiple clinicians and compared over time
    • Disadvantages: Can take time to organise. Requires expertise to interpret. Will miss paroxysmal AF if done between episodes
    • Variations: long term electrical recordings can be used to investigate patients with paroxysmal AF. AHA/ACC/HRS guidelines (2014) also suggest that exercise ECGs can be used where symptoms are associated with exertion
    • Key findings: irregularly irregular QRS complexes with a fibrillating baseline devoid of p-waves confirm the presence of AF. ECGs can also provide evidence for underlying heart disease that can contribute to AF
    • Follow-up: NICE guidelines (2014) state that patients with AF should receive a management plan. A normal ECG does not rule out AF and a consideration should be made towards longer term recordings to investigate the possibility of paroxysmal AF

  • Long term electrical recordings such as 24 hour ECGs and event recorders are also confirmatory investigations with similar properties to ECG recordings
    • Indication: NICE guidelines (2014) mention these as strategies that can be used to confirm the presence of AF in patients who remain without a diagnosis following normal ECG recordings. This is most commonly the case in patients with paroxysmal AF who receive ECG recordings between episodes
    • Advantages: as they record over a longer period of time, long term recordings and more likely to catch episodes of paroxysmal AF, allowing patients with this condition to be diagnosed and receive appropriate treatment
    • Disadvantages: as they record over a longer period of time, long term recordings and more likely to catch episodes of paroxysmal AF, allowing patients with this condition to be diagnosed and receive appropriate treatment
    • Key Findings: are most often communicated to physicians via reports from an interpreting clinician
    • Follow-up: If AF is found, as with ECG recording, NICE guidelines (2014) state that patients should receive a management plan

In addition to the above investigations, which only aim to diagnose AF, patients with suspected and confirmed AF should also receive investigations which aim to look for the aetiology of their AF and for factors that may affect the management of their AF. Finding the cause of a patients AF is key as these underlying risk factors often need to be addressed for the condition to the managed successfully. The 2014 AHA/ACC/HRS guidelines provide a minimum initial clinical workup of such patients and the list below, which is based on this workup, includes the key major investigations that should be considered to achieve these aims:

  • Clinical Examination
    • Key examinations to consider include but are not limited to the respiratory, thyroid status, neurological and cardiovascular examinations
    • These examinations can reveal key information regarding underlying risk factors, as well as aspects of a patients presentation, like the presence of acute neurology, which require immediate changes in management

  • Blood Tests are used in patients to look for a number of underlying contributing factors to AF, such as thyrotoxicosis and anaemia. They are also key for management in the absence of risk factors as many medications require blood monitoring in order to be safely prescribed. Key tests to consider include:
    • Full blood count (FBC)
    • Urea and electrolytes (U&Es)
    • Liver Function Tests (LFTs)
    • Thyroid function tests (TFTs)
    • Calcium and Magnesium (Ca and Mg)
    • Blood glucose (finger prick and blood)

  • ECG recordings can show signs of underlying heart disease and all readings should be scrutinised for this, including those that were used to confirm an initial diagnosis of AF

  • Transthoracic Echocardiography (‘echo’) can be used as part of the management of AF, and to look for underlying heart disease. During management echocardiograms can be used to look for the presence of atrial clots, which are a contradiction to certain management approaches, but they are most commonly used to look for underlying cardiac conditions
    • Indication: 2014 NICE guidelines recommend that echocardiograms should be used in patients where the investigation may aid in acute or long term management or in whom an underlying cardiac risk factor is suspected. In contrast the 2014 AHA/ACC/HRS guidelines recommend echocardiograms are used in all patients with a diagnosis of AF, but this may not be feasible in many clinical contexts
    • Advantages: echocardiography can, in a non invasive fashion, reveal information about both the structure and function of the heart, including pressure information and information about pericardial structures. Scans can also be recorded and read by multiple clinicians
    • Disadvantages: echocardiograms are generally only possible in secondary care with experienced operators, and are time and resource intensive
    • Variations: transoesophageal echocardiography can be used where the transthoracic approach is unsuccessful, but this is significantly more invasive
    • Key Findings: echocardiograms require specific training in order to correctly interpret. Most non-specialist physicians will benefit from a report from an experienced interpreting clinician

  • Chest X-Rays can be used in patients where an underlying respiratory disease is suspected to contribute to presence of AF

Differential diagnosis

With respect to key signs:
  • Irregular pulse:
    • A regularly irregular pulse can be due to second- or third-degree heart block. When in doubt, use an ECG to differentiate these bradyarrhythmias from AF

With respect to key symptoms:
  • Palpitations:
    • Most atrial arrythmias can cause a symptom of palpitations. This includes but is not limited to atrial flutter, AVNRTs and AVRTs
    • Ventricular ectopic beats
    • Sinus tachycardia
    • Anxiety and anxiety attacks
    • Thyroid disease
  • Ischaemia due to cardiac emboli
    • Endocarditis

With respect to ECG findings:
  • Irregular QRS complexes
    • Second- and third-degree heart block
  • Irregular baselines
    • Atrial flutter
    • Ventricular fibrillation
  • Loss of p-waves
    • Hyperkalaemia


2014 NICE guidelines recommend that patients with AF should be offered a management plan at the point of diagnosis. It is widely accepted that the aim of management is to control symptoms and to reduce the risk of complications. In addition to this, patients who present with life threatening symptoms or complications need to have these acute needs managed first before this treatment can be initiated. Finally management plans must also include follow up, so that treatments can be adjusted as patient factors change.

In this section we will first introduce the major treatments used to control symptoms and reduce risk in the majority of patients with AF. We will then discuss how these treatments, as well as emergency treatments in the acute setting and follow-up in the community setting, can be integrated into a plan using current guidance. The majority of this section will be based on NICEs 2014 guidelines and 2020 CKS article. 2014 AHA/ACC/HRS guidelines and information from the British National Formulary (BNF) will also be used with the aim of providing readers with a more rounded view of the management of AF.

Major Treatments used in AF

The main strategies for controlling symptoms are rate and rhythm control.

  • Rate Control is the use of medication to decrease the heart rate at rest and during exertion. This is effective at controlling symptoms because symptoms are normally associated with high heart rates. Patients managed with rate control continue to have AF but are less symptomatic. NICE guidelines (2014), NICE BNF (n.d.) and AHA/ACC/HRS guidelines (2014) recommend the following medications for this:
    • Beta-Blockers, with the exception of sotalol which is used for rhythm control
    • Non-Dihydropyridine Calcium Channel Blockers such as verapamil and diltiazem
    • NICE (2014) recommend that physicians should decide between these two drugs based on patient factors, such as co-morbidities
    • Digoxin can be used, but NICE (2014) do not recommended its use outside of sedentary patients with non-paroxysmal AF
    • It is important to note that, as mentioned in the AHA/ACC/HRS guidelines (2014) and by Burns (2019), the above drugs as well as amiodarone (which is used for rhythm control) are potentially harmful in those with Wolf-Parkinson-White syndrome and other pre-excitation syndromes in association with AF. As mentioned by Burns (2019), DC cardioversion is generally preferred in these patients in the acute setting, and accessory pathway ablation is recommended by the AHA/ACC/HRS guidelines (2014) as a management option in certain patients
    • NICE CKS (2020) suggest that clinicians aim for a resting heart rate of 60 to 80 in patients taking rate control, going up to 90-115 bpm during exertion
    • If required, NICE BNF (n.d.) advise that rate control can be intensified by using the above drugs in combination but if this is not effective then specialist management under cardiology is warranted
    • In terms of the application of rate control in practice, Gutierrez and Blanchard (2016) note in American Family Physician that rate control is generally used more often than rhythm control, as the constituent drugs have better side effect profiles and there is no need to worry about patients coming out of sinus rhythm, as one would for rhythm control patients
  • Rhythm Control aims to control symptoms by restoring the normal contraction of the atria (cardioversion). NICE guidelines (2014) and NICE BNF (n.d.) note that this can be achieved by the following methods:
    • DC Cardioversion, which is the use of electrical stimulation to restore sinus rhythm. NICE BNF (n.d.) note that anti-arrhythmic medication or beta-blocker therapy can subsequently be used to maintain sinus rhythm
    • Amiodarone, which is an antiarrhythmic drug which can restore sinus rhythm on its own. It is suitable in most patients
    • Flecainide, which is an antiarrhythmic drug that can be used in some patients to restore sinus rhythm, but is contraindicated in those with possible structural or ischaemic heart disease
    • NICE BNF (n.d.) notes that all of the above methods must be initiated in secondary care. NICE guidelines (2014) also state that the use of cardioversion is an indication for echocardiogram
    • Patients who are successfully cardioverted are no longer symptomatic but may have a risk of coming out of sinus rhythm and returning to AF. Gutierrez and Blanchard (2016) note that this is can be of concern as maintaining sinus rhythm in certain patients, particularly those over 65, can be a struggle and the medication above can be toxic

More invasive control methods mentioned within major guidelines and described in more detail by Gutierrez and Blanchard (2016), include ablation and pacing, where the atrioventricular node (AVN) is ablated and ventricular contraction controlled by a pacemaker, and the maze procedure and ablation therapy, where the electrical pathways in the heart are manipulated such that AF is less likely to occur.

The prevention of complications should be considered alongside the above strategies for managing symptoms. The main method used for this is anticoagulation. Anticoagulation is effective as it decreases the risk of emboli forming in the heart, but it can also increase the risk of serious bleeds, so patients should only be recommended anticoagulation if the benefits outweigh the risks.

  • Anticoagulation is the use of medication in order to reduce the ability of the blood to clot. These medications can be split into non-oral medications, which are used acutely, and oral anticoagulants, which are used for long term risk control. Medications listed by NICE guidelines (2014), NICE BNF (n.d.) and AHA/ACC/HRS guidelines (2014) that can be used to achieve anticoagulation in AF include:
    • Heparin and Low Molecular Weight Heparin (LMWH) are non-oral anticoagulants that are most commonly used in the acute setting over a short length of time or while oral therapy is initiated. Heparin and LMWH are easily cleared by the body, so their anticoagulant effect is lost soon after treatment is stopped
    • Warfarin is an oral anticoagulant used in certain patients. It requires regular INR monitoring because of its various drug and food interactions, which can mean its anticoagulant effect can be unreliable unless monitored closely. AHA/ACC/HRS guidelines (2014) recommend that doses of warfarin are changed based on these results to achieve an INR of 2-3 for most patients without valve disease, although exact targets may vary based on co-morbidities. Warfarin also needs to be prescribed with LMWH until its anticoagulant effect is established, as it is initially prothrombotic
    • Direct Oral Anticoagulants (DOACs) are a group of oral anticoagulants including Rivaroxaban, Apixaban and Dabigatran. They are now some of the most commonly used medications in this group. They have a highly predictable and reliable anti-coagulant effect and therefore require reduced blood monitoring compared to warfarin. They do no need to be prescribed with LMWH, but their action is more difficult to reverse

Current Guidance

As discussed briefly at the start of this section, the successful management of AF can be seen to involve the following steps:

  • Initial assessment for and management of emergency symptoms
    • Treatment of haemodynamic instability
    • Treatment of complications
  • Management of non life threatening symptoms
    • Rhythm and Rate Control
    • Investigation and management of underlying causes of AF
  • Management of the risk of complications
    • Anticoagulation
  • Follow-up in primary care

With this in mind the rest of this section will aim to describe the treatment of patients with AF using the steps described above.

Treatment of Haemodynamic Instability

Patients with haemodynamic instability nearly always present to secondary care directly, and are best managed in units with access to resuscitation equipment and cardiology support. The minority of patients who present to primary care with these signs should not be missed, and should immediately be referred to secondary care as an emergency.

The treatment of these patients is as follows:

  • Initial assessment should follow an ABCDE approach with early senior involvement
    • If AF is not suspected at presentation it should become obvious from a thorough ABCDE assessment
  • NICE guidelines (2014) recommend that if AF is found to be the cause of haemodynamic instability it should be treated with immediate DC cardioversion

After cardioversion patients should be reassessed for any further needs.

After the acute situation has passed patients should be looked after in an environment where an appropriate level of support can be provided. Patients may need to receive care for cardiac ischaemia or other sequelae of haemodynamic compromise.

Treatment of Complications

The major complications of AF are embolic phenomena, namely stroke, mesenteric ischaemia or acute limb ischaemia. Symptoms associated with these diseases require treatment in secondary care on an emergency basis. While all of these diseases are likely to present to secondary care, the symptoms of stroke in particular are sometimes missed by members of the public and therefore seen in primary care. If this is the case an emergency admission to secondary care is always required.

These patients should be treated as an emergency and with an ABCDE approach. The most urgent condition should be treated first. In most cases this will mean the acute management of the complication of AF will occur before the acute management of the AF itself.

After the acute phase of management has passed the most common area of confusion with regards to AF is how its anticoagulation regime overlaps with the anticoagulation requirements of other conditions. In the case of stroke in particular, which is the most common complication of AF, it can be unclear to physicians how aspirin and warfarin/DOAC anticoagulation regimes should interact, if at all. NICE guidelines on the management of stroke in this context (2019) recommend that patients are given aspirin for 2 weeks, which is standard for the management of stroke, and initiated on anticoagulant therapy with warfarin or a DOAC as soon as possible after but not during this time.

Management of non life-threatening symptoms

Patients with symptomatic AF require acute management in order to resolve their symptoms. While the majority of these patients present to and are therefore managed in secondary care, NICE CKS (2020) notes that patients who present in primary care can be managed there if this is appropriate based on both their presentation and the treatments they require. In primary care it is particularly important to note that patients with AF should always be screened thoroughly for complications and haemodynamic compromise, as the presence of these always requires emergency secondary care admission.

Strategies for the acute management of symptoms vary depending on the onset of AF. NICE guidelines (2014) recommend that patients with a new onset of AF, i.e. those who were previously in sinus rhythm, receive the following package of care:

  • Those who have had symptoms for less than 48 hours can be offered rhythm control or rate control
    • Rhythm control is recommended in most patients with a new onset of AF presenting at this time
  • Those who have had symptoms for more than 48 hours or who have an uncertain onset of AF (either asymptomatic patients or patients with an uncertain onset of symptoms) can be offered immediate rate control followed by delayed rhythm control if they desire it. This means that while all patients start on rate control, they can choose either rhythm or rate control as a long term strategy to manage their symptoms
    • Rate control is the first line treatment for long term management. Exceptions to this include patients with AF that have a clear reversible trigger and patients who may benefit more from rhythm control
    • Delayed rhythm control refers to cardioversion that takes place after at least 3 weeks of anticoagulation and rate control. It is recommended to only use DC cardioversion for this function. The aim of anticoagulation is to remove atrial clots, reducing the risk of stroke immediately following cardioversion. NICE BNF (n.d.) notes that these patients should continue to receive anticoagulation for 4 weeks after their cardioversion to further reduce this risk. If anticoagulation cannot be given before cardioversion then a transoesophageal echocardiogram guided cardioversion should be done to make sure there are no clots in the atria beforehand

Patients who have previously been diagnosed with AF, and are therefore experiencing worsening symptoms despite their current management strategy should have this assessed and, after receiving acute management for their symptoms, be offered treatment that aims to address their needs for long term management:

  • Patients who were previously in sinus rhythm are considered to have a new onset of AF and should be initially managed as above. Patients in this group include those already being managed with rhythm control and those with paroxysmal AF
  • If patients previously using a rhythm control strategy want to continue with this, explore methods to maintain sinus rhythm more effectively after cardioversion. This can include anti-arrhythmic medication over the longer term to help prevent further episodes of AF
  • Patients with paroxysmal AF qualify for a slightly altered initial and long term management strategy:
    • NICE BNF (n.d.) recommends that these patients are offered rate control as a first line
    • NICE BNF (n.d.) also notes that patients with very infrequent episodes of paroxysmal AF can be candidates for a ‘pill in the pocket’ approach where they are given oral-antiarrhythmics to take whenever they feel like they are going into AF
  • Patients who already receive rate control, and are therefore experiencing symtpoms despite taking the appropriate medication, may require more intense therapy or specialist referral for their long term management

The investigation and management of underlying causes of AF

The investigation and management of underlying diseases and modifiable risk factors for AF, as detailed in the Investigations section, must also be considered at this stage. Addressing these can aid in the control of symptoms and help prevent mortality and morbidity both from AF and by allowing physicians and patients to address the consequences of these underlying issues themselves.

  • Patients with a new diagnosis of AF require investigations to assess for undiagnosed underlying diseases and a detailed history and examination to assess for modifiable risk factors
  • All patients with AF will benefit from investigations to look for any obvious triggers for their symptoms


Anticoagulation should be considered alongside the symptomatic management of AF in patients being treated with both rhythm and rate control. NICE guidelines (2014) recommend the following with respect to anticoagulation prescription in AF:

  • Patients with a new onset of AF and who are not already on anticoagulants can be given heparin until the need for longer term oral anticoagulation can be assessed
  • Patients who have presented within 48 hours of the onset of symptoms and who have been started on heparin can stop receiving anticoagulation providing:
    • Cardioversion restores a stable sinus rhythm within the 48 hour period from the onset of their symptoms and
    • They have a low risk of recurrence of their AF
  • All other patients matching the criteria below should be assessed for oral anticoagulation to replace their heparin. The result of this assessment will determine whether or not patients stop receiving anticoagulation altogether, or if they will receive long term oral anticoagulation to replace their heparin
    • Patients who continue to have AF, whether is it paroxysmal or persistent should receive an assessment
    • Patients who are in sinus rhythm but have a high risk of recurrence of their AF should receive an assessment. Patients with a high risk of recurrence include those with structural heart disease, including valvular disease, previous recurrences of AF or if they have had a history of AF for over 12 months

NICE guidelines (2014) recommend that patients who meet the criteria for assessment are assessed via the CHA₂DS₂-VASc score, first developed by Lip et al. (2010), their version of which is detailed in the table below. NICE criteria state that a score of 2 or more indicates a high enough risk of stroke to warrant anticoagulant therapy in all patients, and a score of 1 is enough to prompt consideration of this in men only. After this, clinical judgement regarding risk of bleeding should be used to determine whether anticoagulant therapy should actually be started. NICE (2014) recommends the HASBLED score, first developed by Pisters et al. (2010) and detailed below, for this purpose. HAS-BLED can also be used as a memory aid for the main modifiable and non-modifiable risk factors to consider when thinking about bleeding risk.

Criteria for scoring in past medical historyPoints per criterion present
Congestive Heart Failure1
Age1 if 65 or over, 2 if 75 and over
Diabetes Mellitus1
Stroke (including TIA and other thromboembolic disease)2
Vascular Disease1
Sex category1 if female

Criteria for scoring in past medical historyPoints per criterion present
Abnormal renal or liver function1 for each of liver or renal function
Labile (i.e. variable) INRs1
Elderly (age >65)1
Drugs predisposing to bleeds including alcohol use >8 units/week1 for the presence of a drug, 1 for the presence of the required alcohol intake

When prescribing oral anticoagulation consideration must also be made as to which oral anticoagulant is best for the patient. Key points to consider include the renal and liver function of your patient, as well the potential impact of non-reversible anticoagulation in the case of DOACs against the monitoring requirements of warfarin.


Follow-up care for patients is the final key stage of management. This mainly takes place in primary care, but can sometimes include referral to secondary care if symptoms are refractory to management or if assessment and management of underlying risk factors for AF needs to occur. Putting secondary care follow-up aside, NICE CKS (2020) suggest that patients with AF should be seen in primary care as follows:

  • 1 week after the initiation of rate control, or after any changes to rate control. Clinicians should look into patient compliance and tolerance of treatment, and change treatment as necessary. Patients with uncontrolled symptoms even after attempting combination treatment should be referred to be seen by cardiology within 4 weeks
  • Annually, or more often as required, for all patients with a diagnosis of AF. Patients should:
    • Receive a symptom review, which should include asking about symptoms of AF at rest and during exercise, and assessing for symptoms of cardiovascular disease and of complications of AF
    • Receive a medication review, which should include reassessing the need for, adequacy, and effectiveness of the current AF management strategy being used, including anticoagulation
    • Patients should be seen more often based on clinical judgement.
    • NICE guidelines (2014) and NICE CKS (2020) also recommend that patients who are not on anticoagulation should be seen to review their need for this treatment once they are 65 or develop diabetes, heart failure, peripheral arterial disease, coronary heart disease or stroke/TIA, in addition to their annual reviews

In addition to the above primary care reviews patients on anticoagulation should be followed up and receive blood tests as required based on the monitoring requirements of these medications.

Speciality referral for AF, outside of when there is an acute need, is appropriate under NICE guidelines (2014) where the treatment for AF is unsuccessful despite combination rate treatment. Specialist referral is also suggested by Gutierrez and Blanchard (2016) when patients want to begin rhythm control or other treatments that require specialist input, and when patients are found to have underlying diseases that require specialist management, investigation or input.


Major complications of AF are those that result from cardiac emboli. These emboli can result in lesions in any organ system but the most common ones to be aware of are as below:
  • Brain → stroke
  • Limb Arteries → acute limb ischaemia
  • Mesentery → mesenteric Ischaemia

Stroke is the most common complication of AF and modification of the risk of stroke is the main justification for interventions such as anticoagulation.