Module 1: Definition: Types, Causes and Presentation

Atrial fibrillation

Atrial fibrillation (AF) is a medical condition affecting the heart. In a normal functioning heart there should be a regular synchronised rhythm, and a resting heart rate of 60 to 90 beats per minute. In AF there is an irregular rhythm and in many cases an increased heart rate.

The increased heart rate and irregular rhythmic contractions of the heart can cause many problems, including tiredness dizziness and shortness of breath (SOB). Palpitations (heart feels like its pounding/ fluttering/ beating irregularly) which may last for a few seconds to a few minutes. In many cases, atrial fibrillation can go asymptomatic (un-noticed) and often many patient will live normal lives without realising that their heart is unsynchronised.

Atrial fibrillation – Explained:

Atrial fibrillation is a form of atrial tachyarrhythmia, like all atrial tachyarrhythmia’s the problem lies with the atrial myocardium. (2). Normally the Sino atrial node sends out regular electrical impulses which cause the atrial myocardium to contract in an organised fashion and then pass on the electrical impulse to the ventricles via the atrio-ventricular node. In atrial fibrillation, the electrical impulses are firing at different places in an unorganised manner and this often causes the ventricular response to be altered leading to a fast, irregularly irregular pulse.

Atrial fibrillation occurs in 1-2% of general population and in 5-10% of those over 75 years. The most common causes are hypertension and heart failure, with rheumatic heart disease, thyrotoxicosis and alcohol intoxication also causing AF(2) . Interestingly, following cardiac surgery 33% of patients will get AF and there is an association with vigorous exercise and recurrent episodes of AF (3). The main risks of having atrial fibrillation is a potential blood clot to a cerebral artery (causing stroke) or an embolism occluding a vital artery elsewhere in the body causing circulatory failure, both lead to very high mortality rates if left undiagnosed and untreated. (2)

Overview of AF

Anatomy of the heart

The heart has four chambers, two upper chambers – right and left atria and two lower chambers right and left ventricles.

In the right atrium there is a group of cells - The sinus atrial node (SIN). This is the hearts natural pacemaker. The sinus node produces the impulses starts each heartbeat.

Normally, the impulse travels first through the atria and then through a connecting pathway between the upper and lower chambers of your heart called the atrioventricular (AV) node. As the signal passes from the sinus node through the atria, they contract, pumping blood from your atria into the ventricles below. As the signal passes through the AV node to the ventricles, it signals the ventricles to contract, pumping blood out to your body.

In atrial fibrillation, the upper chambers of your heart (atria) experience chaotic electrical signals. As a result, they quiver. The AV node — the electrical connection between the atria and the ventricles — is bombarded with impulses trying to get through to the ventricles.

The ventricles also beat rapidly, but not as rapidly as the atria, as not all the impulses get through. The reason is that the AV node is like a highway on-ramp — only so many vehicles can get on at one time.

The result is a fast and irregular heart rhythm. The heart rate in atrial fibrillation may range from 100 to 175 beats a minute.

Types of atrial fibrillation

There are 4 main types of atrial fibrillation:

1) Paroxysmal Atrial Fibrillation (PAF)

2) Persistent Atrial Fibrillation

3) Long standing persistent Atrial Fibrillation

4) Permanent Atrial Fibrillation

1) Paroxysmal Atrial Fibrillation

• The faulty electrical signals and rapid heart rate begin suddenly and then stop on their own. Symptoms can be mild or severe. They stop within about a week, but usually in less than 24 hours.
• Self-terminating usually within 48 hours, if AF continues past this point then anticoagulation needs to be considered
• This type of AF is recurrent

2) Persistent Atrial fibrillation

• Persistent AF is a condition in which the abnormal heart rhythm continues for more than 7 days or resolves with treatment by intervention.
• Cardioversion either by Direct current cardio version (DCC) or medication is needed in order to restore sinus rhythm.
• This type of AF has a chance of recurrence

3) Long standing persistent AF

This is when there is continuous AF for 1 year or longer

4) Permanent AF

• Permanent AF is a condition in which a normal heart rhythm can't be restored with treatment.
• Rhythm control interventions have not worked
• This type of AF is not curable
• Both paroxysmal and persistent AF may become more frequent and, over time, result in permanent AF.

Causes of Atrial Fibrillation

Abnormalities or damage to the heart's structure are the most common cause of atrial fibrillation. Possible causes of atrial fibrillation include:

Hereditary

• High blood pressure
• Coronary artery disease
• Abnormal heart valves
• Congenital heart defects
• An overactive thyroid gland

Acquired

• Heart attacks
• Metabolic imbalances
• Exposure to stimulants, such as medications, caffeine, tobacco or alcohol
• Sick sinus syndrome — improper functioning of the heart's natural pacemaker
• Lung diseases
• Previous heart surgery
• Viral infections
• Increased Stress
• Sleep apnoea

Note: Lone AF is a condition where the patient has a normal structured anatomy of the heart and no known causes of AF are found. It is found in a relatively small number of people and those that have the disease rarely suffer from serious complications of AF.

Presentation

Symptoms

Some people with atrial fibrillation have no symptoms and are unaware of their condition until it's discovered during a physical examination. Those who do have atrial fibrillation symptoms may experience signs and symptoms such as:

• Palpitations (which is a sensation/awareness of a uncomfortably irregular heartbeat)
• Weakness
• Reduced ability to exercise
• Fatigue
• Light-headedness
• Dizziness
• Confusion
• Shortness of breath
• Chest pain

Risk factors for getting AF

Factors that increase the risk of getting AF include:

Modifiable

• Obesity. People who are obese are at higher risk of developing atrial fibrillation.
• Drinking alcohol. For some people, drinking alcohol can trigger an episode of atrial fibrillation. Binge drinking may put you at an even higher risk.
• High blood pressure. Having high blood pressure, especially if it's not well-controlled with lifestyle changes or medications can increase your risk of atrial fibrillation.

Not Modifiable

• Heart disease. Anyone with heart disease — such as heart valve problems, congenital heart disease, congestive heart failure, coronary artery disease, or a history of heart attack or heart surgery — has an increased risk of atrial fibrillation.
• Age. The older you are, the greater your risk of developing atrial fibrillation
• Chronic conditions. People with certain chronic conditions such as thyroid problems, sleep apnea, metabolic syndrome, diabetes, chronic kidney disease or lung disease have an increased risk of atrial fibrillation.
• Family history. An increased risk of atrial fibrillation is present in some families.

Complications

The two most common complication of AF are:

1) Stroke

2) Heart Failure

1) Stroke.

In atrial fibrillation, the chaotic rhythm may cause blood to pool in your atria and form clots. If a blood clot forms, it could turn to an embolus by dislodging from your heart and travelling to the brain. Once in the brain it might block blood flow, causing a stroke. In people who suffer from AF - There is an increase risk as you age of getting a stroke. Certain medications, such as blood thinners, can greatly lower the risk of a stroke or the damage to other organs caused by blood clots.

2) Heart failure.

Atrial fibrillation, especially if not controlled, may weaken the heart and lead to heart failure — a condition in which your heart can't circulate enough blood to meet your body's needs.

Module 2: Diagnosis, Investigations and Management

Key:

History and Examination

Investigations

Management

- Assessment of stroke and bleeding risks

- Management of Chronic AF

- Cardioversion

- Anticoagulation

- Prevention and management of postoperative atrial fibrillation

 

 

Diagnosis:

Key diagnostic factors From History and Examination

Risk factors

• Increasing Age
• Diabetes Mellitus
• Congestive Heart failure
• Valvular disease
• Coronary artery disease
• hyperthyroidism
• Cardiac surgery

Irregular pulse

• irregularly irregular pulse

Palpitations

• Heart feels like its galloping/ fluttering

Hypotention

Added heart sounds

• Gallop rhythm
• No S4 heart sound heard

Investigations:

Nice Recommendations for Investigations

1) ECG: Whether symptomatic or not, in whom atrial fibrillation is suspected because an irregular pulse has been detected.

2) 24 hour ambulatory ECG monitor in those with suspected asymptomatic episodes or symptomatic episodes less than 24 hours apart

3) Event recorder ECG in those with symptomatic episodes more than 24 hours apart.

4) Transthoracic echocardiography (TTE) in people with atrial fibrillation:

• For whom a baseline echocardiogram is important for long term management
• For whom a rhythm control strategy that includes cardioversion (electrical or pharmacological) is being considered
• In whom there is a high risk or a suspicion of underlying structural/functional heart disease (such as heart failure or heart murmur) that influences their subsequent management (for example, choice of antiarrhythmic drug)

5) Transoesophageal echocardiography (TOE) in people with atrial fibrillation:

• When TTE demonstrates an abnormality (such as valvular heart disease) that warrants further specific assessment
• In whom TTE is technically difficult and/or of questionable quality and where there is a need to exclude cardiac abnormalities
• For whom TOE guided cardioversion is being considered.

Referral for specialised management

Refer people promptly at any stage if treatment fails to control the symptoms of atrial fibrillation and more specialised management is needed.

Management: 

Interventions to prevent stroke

Do not offer stroke prevention therapy to people aged under 65 years with atrial fibrillation and no risk factors other than their sex (that is, very low risk of stroke equating to a CHA2DS2-VASc score of 0 for men or 1 for women).

 

Assessment of stroke and bleeding risks

Stroke risk

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

• symptomatic or asymptomatic paroxysmal, persistent or permanent atrial fibrillation

• atrial flutter

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

Bleeding risk

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:

• 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.

When discussing the benefits and risks of anticoagulation, explain to the person that:

• for most people the benefit of anticoagulation outweighs the bleeding risk

• for people with an increased risk of bleeding the benefit of anticoagulation may not always outweigh the bleeding risk, and careful monitoring of bleeding risk is important.

Do not withhold anticoagulation solely because the person is at risk of having a fall.

Management of Chronic AF

Rate and Rhythm control

When to offer rate or rhythm control

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.

Rate control

Offer either a standard beta blocker (that is, a beta blocker other than sotalol) or a rate limiting calcium channel blocker as initial monotherapy to people with atrial fibrillation who need drug treatment as part of a rate control strategy. Base the choice of drug on the person's symptoms, heart rate, comorbidities and preferences when considering drug treatment.

Consider digoxin monotherapy for people with non paroxysmal atrial fibrillation only if they are sedentary (do no or very little physical exercise).

If monotherapy does not control symptoms, and if continuing symptoms are thought to be due to poor ventricular rate control, consider combination therapy with any 2 of the following:

• a beta blocker

• diltiazem

• Digoxin.

Do not offer amiodarone for long term rate control.

Rhythm control

Consider pharmacological and/or electrical rhythm control for people with atrial fibrillation whose symptoms continue after heart rate has been controlled or for whom a rate control strategy has not been successful.

Cardioversion

For people having cardioversion for atrial fibrillation that has persisted for longer than 48 hours, offer electrical (rather than pharmacological) cardioversion.

Consider amiodarone therapy starting 4 weeks before and continuing for up to 12 months after electrical cardioversion to maintain sinus rhythm, and discuss the benefits and risks of amiodarone with the person.

For people with atrial fibrillation of greater than 48 hours' duration, in whom elective cardioversion is indicated:

Both transoesophageal echocardiography (TOE) guided cardioversion and conventional cardioversion should be considered equally effective

A TOE guided cardioversion strategy should be considered:

• where experienced staff and appropriate facilities are available and

• Where a minimal period of precardioversion anticoagulation is indicated due to the person's choice or bleeding risks.

Drug treatment for long term rhythm control

Assess the need for drug treatment for long term rhythm control, considering the person's preferences, associated comorbidities, risks of treatment and likelihood of recurrence of atrial fibrillation.

If drug treatment for long term rhythm control is needed, consider a standard beta blocker (that is, a beta blocker other than sotalol) as first line treatment unless there are contraindications.

If beta blockers are contraindicated or unsuccessful, assess the suitability of alternative drugs for rhythm control, taking comorbidities into account.

Dronedarone is recommended as an option for the maintenance of sinus rhythm after successful cardioversion in people with paroxysmal or persistent atrial fibrillation:

• In whom atrial fibrillation is not controlled by first line therapy (usually including beta blockers), that is, as a second line treatment option and after alternative options have been considered and who have at least 1 of the following cardiovascular risk factors:

  • Hypertension requiring drugs of at least 2 different classes

  • Diabetes mellitus

  • Previous transient ischaemic attack, stroke or systemic embolism

  • Left atrial diameter of 50 mm or greater or

  • Age 70 years or older and

• Who do not have left ventricular systolic dysfunction and

• Who do not have a history of, or current, heart failure.

Consider amiodarone for people with left ventricular impairment or heart failure.

Do not offer class 1c antiarrhythmic drugs such as flecainide or propafenone to people with known ischaemic or structural heart disease.

Where people have infrequent paroxysms and few symptoms, or where symptoms are induced by known precipitants (such as alcohol, caffeine), a 'no drug treatment' strategy or a 'pill in the pocket' strategy should be considered and discussed with the person.

In people with paroxysmal atrial fibrillation, a 'pill in the pocket' strategy should be considered for those who:

• Have no history of left ventricular dysfunction, or valvular or ischaemic heart disease and

• Have a history of infrequent symptomatic episodes of paroxysmal atrial fibrillation and

• Have a systolic blood pressure greater than 100 mmHg and a resting heart rate above 70 bpm and

• Are able to understand how to, and when to, take the medication.

Left atrial ablation + Pace and ablate strategy

Left atrial ablation

If 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

1.6.20Consider left atrial surgical ablation at the same time as other cardiothoracic surgery for people with symptomatic atrial fibrillation

Pace and ablate strategy

Consider pacing and atrioventricular node ablation for people with permanent atrial fibrillation with symptoms or left ventricular dysfunction thought to be caused by high ventricular rates.

When considering pacing and atrioventricular node ablation, reassess symptoms and the consequent need for ablation after pacing has been carried out and drug treatment further optimised.

Consider left atrial catheter ablation before pacing and atrioventricular node ablation for people with paroxysmal atrial fibrillation or heart failure caused by non permanent (paroxysmal or persistent) atrial fibrillation.

Treatment of Acute Atrial Fibrillation

Rate and rhythm control

Carry out emergency electrical cardioversion, without delaying to achieve anticoagulation, in people with life threatening haemodynamic instability caused by new onset atrial fibrillation.

In people with atrial fibrillation presenting acutely without life threatening haemodynamic instability, offer rate or rhythm control if the onset of the arrhythmia is less than 48 hours, and start rate control if it is more than 48 hours or is uncertain.

Consider either pharmacological or electrical cardioversion depending on clinical circumstances and resources in people with new onset atrial fibrillation who will be treated with a rhythm control strategy

If pharmacological cardioversion has been agreed on clinical and resource grounds for new onset atrial fibrillation, offer:

• A choice of flecainide or amiodarone to people with no evidence of structural or ischaemic heart disease or

• Amiodarone to people with evidence of structural heart disease.

In people with atrial fibrillation in whom the duration of the arrhythmia is greater than 48 hours or uncertain and considered for long term rhythm control, delay cardioversion until they have been maintained on therapeutic anticoagulation for a minimum of 3 weeks. During this period offer rate control as appropriate.

Do not offer magnesium or a calcium channel blocker for pharmacological cardioversion.

Anticoagulation

In people with new onset atrial fibrillation who are receiving no, or sub-therapeutic, anticoagulation therapy:

• in the absence of contraindications, offer heparin at initial presentation

• continue heparin until a full assessment has been made and appropriate antithrombotic therapy has been started, based on risk stratification

In people with a confirmed diagnosis of atrial fibrillation of recent onset (less than 48 hours since onset), offer oral anticoagulation if:

• stable sinus rhythm is not successfully restored within the same 48 hour period following onset of atrial fibrillation or

• there are factors indicating a high risk of atrial fibrillation recurrence

Prevention and management of postoperative atrial fibrillation

In people undergoing cardiothoracic surgery:

• reduce the risk of postoperative atrial fibrillation by offering 1 of the following:

  • amiodarone

  • a standard beta blocker (that is, a beta blocker other than sotalol)

  • a rate limiting calcium antagonist

• do not offer digoxin.

In people undergoing cardiothoracic surgery on pre existing beta blocker therapy, continue this treatment unless contraindications develop (such as postoperative bradycardia or hypotension).

Unless contraindicated, offer a rhythm control strategy as the initial management option for the treatment of postoperative atrial fibrillation following cardiothoracic surgery.

Unless contraindicated, manage postoperative atrial fibrillation following non cardiothoracic surgery as for new onset atrial fibrillation with any other precipitant.

In the prophylaxis and management of postoperative atrial fibrillation, use appropriate antithrombotic therapy and correct identifiable precipitants (such as electrolyte imbalance or hypoxia).

 

Module 3: Anticoagulation Drugs

Anticoagulation may be with Apixaban, Dabigatran etexilate, Rivaroxaban, Edoxaban or a vitamin K antagonist.

Consider anticoagulation for men with a CHA2DS2-VASc score of 1. Take the bleeding risk into account.

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

Discuss the options for anticoagulation with the person and base the choice on their clinical features and preferences.

Apixaban

Apixaban is recommended as an option for preventing stroke and systemic embolism within its marketing authorisation, that is, in people with nonvalvular atrial fibrillation with 1 or more risk factors such as:

• prior stroke or transient ischaemic attack

• age 75 years or older

• hypertension

• diabetes mellitus

• symptomatic heart failure.

Dabigatran etexilate

Dabigatran etexilate is recommended as an option for the prevention of stroke and systemic embolism within its licensed indication, that is, in people with nonvalvular atrial fibrillation with one or more of the following risk factors:

• previous stroke, transient ischaemic attack or systemic embolism

• left ventricular ejection fraction below 40%

• symptomatic heart failure of New York Heart Association (NYHA) class 2 or above

• age 75 years or older

• age 65 years or older with one of the following: diabetes mellitus, coronary artery disease or hypertension.

Rivaroxaban

Rivaroxaban is recommended as an option for the prevention of stroke and systemic embolism within its licensed indication, that is, in people with nonvalvular atrial fibrillation with one or more risk factors such as:

• congestive heart failure

• hypertension

• age 75 years or older

• diabetes mellitus

• prior stroke or transient ischaemic attack.

Edoxaban

Indications

Nonvalvular AF to reduce the risk of stroke and systemic embolism. For nonvalvular AF, edoxaban should not be used in patients with CrCl greater than 95 mL/minute due to an increased risk of ischemic stroke compared to warfarin at 60 mg. DVT or PE treatment after 5 to 10 days of initial parenteral anticoagulant.

Contraindications to Edoxiban

• Hypersensitivity to the active substance or to any of the excipients listed in SPC

• Clinically significant active bleeding.

• Hepatic disease associated with coagulopathy and clinically relevant bleeding risk.

• Lesion or condition, if considered to be a significant risk for major bleeding. This may include current or recent gastrointestinal ulceration, presence of malignant neoplasms at high risk of bleeding, recent brain or spinal injury, recent brain, spinal or ophthalmic surgery, recent intracranial haemorrhage, known or suspected oesophageal varices, arteriovenous malformations, vascular aneurysms or major intraspinal or intracerebral vascular abnormalities.

• Uncontrolled severe hypertension.

• Concomitant treatment with any other anticoagulants e.g. unfractionated heparin (UFH), low molecular weight heparins (enoxaparin, dalteparin, etc.), heparin derivatives (fondaparinux, etc.), oral anticoagulants (warfarin, dabigatran etexilate, rivaroxaban, apixaban etc.) except under specific circumstances of switching oral anticoagulant therapy or when UFH is given at doses necessary to maintain an open central venous or arterial catheter.

• Pregnancy and breast-feeding.

Assessing anticoagulation control with vitamin K antagonists:warfarin, phenprocoumon and acenocoumaro

Calculate the person's time in therapeutic range (TTR) at each visit. When calculating TTR:

• use a validated method of measurement such as the Rosendaal method for computer assisted dosing or proportion of tests in range for manual dosing

• exclude measurements taken during the first 6 weeks of treatment

• calculate TTR over a maintenance period of at least 6 months

Reassess anticoagulation for a person with poor anticoagulation control shown by any of the following:

• 2 INR values higher than 5 or 1 INR value higher than 8 within the past 6 months

• 2 INR values less than 1.5 within the past 6 months

• TTR less than 65%.

When reassessing anticoagulation, take into account and if possible address the following factors that may contribute to poor anticoagulation control:

• cognitive function

• adherence to prescribed therapy

• illness

• interacting drug therapy

• lifestyle factors including diet and alcohol consumption.

If poor anticoagulation control cannot be improved, evaluate the risks and benefits of alternative stroke prevention strategies and discuss these with the person.

Antiplatelets

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

Review of people with atrial fibrillation

For people who are not taking an anticoagulant, review stroke risk when they reach age 65 or if they develop any of the following at any age:

• diabetes

• heart failure

• peripheral arterial disease

• coronary heart disease

• stroke, transient ischaemic attack or systemic thromboembolism

For people who are not taking an anticoagulant because of bleeding risk or other factors, review stroke and bleeding risks annually, and ensure that all reviews and decisions are documented.

For people who are taking an anticoagulant, review the need for anticoagulation and the quality of anticoagulation at least annually, or more frequently if clinically relevant events occur affecting anticoagulation or bleeding risk.

Here are the links to the following websites for further reading around Atrial Fibrillation

Nice https://www.nice.org.uk/guidance/cg180

ESC https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Atrial-Fibrillation-Management

AHA http://www.onlinejacc.org/content/64/21/2304

BCS https://www.bcs.com/pages/news_full.asp?NewsID=19791971

BHF https://www.bhf.org.uk/heart-health/conditions/atrial-fibrillation

Stopafib.org http://www.stopafib.org/