Atrial Fibrillation

oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, characterised by irregularly irregular ventricular pulse and loss of association between the cardiac apex beat and radial pulsation. [1] Loss of active ventricular filling is associated with:

  • Stagnation of blood in the atria leading to thrombus formation and a risk of embolism, increasing the risk of stroke.
  • Reduction in cardiac output (especially during exercise) which may lead to heart failure.
  • Acute: onset within the previous 48 hours.
  • Paroxysmal: spontaneous termination within seven days and most often within 48 hours. Paroxysmal atrial fibrillation (AF) may degenerate into a sustained form of AF.
  • Recurrent:
    • Two or more episodes, which may be defined as paroxysmal if they terminate spontaneously or persistent if the arrhythmia requires electrical or pharmacological cardioversion for termination.
    • Successful termination of AF does not alter the classification of persistent AF.
  • Persistent: not self-terminating; lasting longer than seven days, or prior cardioversion. Persistent AF may degenerate into permanent AF.
  • Permanent:
    • Long-standing AF (defined as over a year) that is not successfully terminated by cardioversion, when cardioversion is not pursued or has relapsed following termination.
    • Reversion of permanent AF to normal sinus rhythm is possible, particularly in those cases where the AF is caused by an underlying disease process which is successfully treated (eg thyroid disease) or where a specialist procedure is performed that modifies the electrophysiological properties of the heart.

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  • Prevalence is approximately 1% of the population.[2]
  • The prevalence increases with age; from 0.7% in people aged 55-59 years to 18% in those older than 85 years.[3]
  • More common in males than in females.
  • Idiopathic ('lone') atrial fibrillation (AF): 5-10% of patients (diagnosis of exclusion with no evidence of any specific underlying cause).
  • Hypertension (especially with associated left ventricular hypertrophy).
  • Coronary artery disease.
  • Valvular heart disease, especially mitral valve stenosis.
  • Cardiac surgery.
  • Myocarditis.
  • Atrial septal defect.
  • Atrial myxoma.
  • Sick sinus syndrome.
  • Pre-excitation syndromes with accessory conduction pathways, eg Wolff-Parkinson-White syndrome.
  • Dilated and hypertrophic cardiomyopathy.
  • Pericardial disease, eg pericardial effusion, constrictive pericarditis.
  • Hyperthyroidism.
  • Acute infections (especially pneumonia in the elderly).
  • Acute excess alcohol intake or chronic excess alcohol intake.
  • Respiratory (lung cancer, chronic obstructive pulmonary disease, pleural effusion, pulmonary embolism, pulmonary hypertension).
  • Other causes include obesity, sleep apnoea, haemochromatosis, sarcoidosis, and narcotic abuse
  • Genetic: autosomal dominant (rare).

There is a spectrum of clinical presentation between asymptomatic and severe heart failure:

  • Asymptomatic in up to 20% of patients: detected as an irregularly irregular pulse rhythm with the cardiac apex rate exceeding the wrist pulse rate, or found incidentally on an ECG.
  • Manual pulse palpation should be used to assess an irregular pulse indicating underlying atrial fibrillation (AF) in patients who present with breathlessness, palpitations, syncope or dizziness, chest discomfort, stroke or transient ischaemic attack (TIA).
  • Palpitations: paroxysmal or persistent.
  • Heart failure, lethargy, fatigue, dyspnoea, chest pain, dizziness.
  • Syncope is rare unless the patient has sick sinus syndrome or Wolff-Parkinson-White syndrome.
  • Arterial pulse is irregularly irregular in rhythm, rate and volume.
  • First heart sound is of variable loudness.
  • Absent 'a' waves in the jugular venous pulse.
  • Apical-radial pulse mismatch develops when the rate is rapid.
  • Atrial flutter.
  • Atrial extrasystoles.
  • Supraventricular tachyarrhythmias.
  • Atrioventricular nodal re-entrant tachycardia.
  • Wolff-Parkinson-White syndrome.
  • Ventricular tachycardia.
  • Atrial fibrillation (AF) is often associated with other arrhythmias, eg atrial flutter or atrial tachycardia.
  • AF can alternate with atrial flutter, atrial flutter may develop into AF and atrial flutter may occur during treatment of AF with anti-arrhythmic drugs.
  • In patients with Wolff-Parkinson-White syndrome, AF can lead to rapid ventricular rates and ventricular fibrillation, especially when AV nodal blocking agents are used.

Further assessment is focused on identifying any underlying cause and assessment of cardiac function:[3]

  • Electrocardiogram should be performed in all patients, whether symptomatic or not, with an irregular pulse in whom atrial fibrillation (AF) is suspected:
    • An ECG is diagnostic except in paroxysmal AF between attacks. The distinguishing feature of AF is variability in the R-R intervals.
    • If paroxysmal AF is suspected and has not been detected by standard ECG recording, a 24-hour ambulatory ECG monitor should be used if asymptomatic episodes are suspected or if episodes are less than 24 hours apart.
    • An event recorder ECG should be used where symptomatic episodes are more than 24 hours apart.
  • Blood tests: TFTs, FBC (anaemia may precipitate heart failure), renal function and electrolytes (abnormal serum potassium levels can potentiate arrhythmias, especially if the patient is taking, or about to start, digoxin), LFTs and coagulation screen (pre-warfarin).
  • CXR (may indicate cardiac structural causes of AF, such as mitral valve disease, or heart failure).
  • Echocardiogram should be considered if the patient is not being referred to a cardiologist but there is reason to suspect underlying heart disease.[4]
  • CT or MRI scan of the brain: should be performed if there is any suggestion of stroke or transient ischaemic attack (TIA).
  • The management of atrial fibrillation (AF) involves control of the arrhythmia (by rhythm or rate control) and thromboprophylaxis to prevent strokes.
  • Treat any underlying cause, eg acute infection, hyperthyroidism. AF may revert on treatment or resolution of an associated problem, eg acute infection or alcohol intoxication.
  • Treat associated heart failure.

No further intervention may be required; lifestyle changes, such as avoiding the precipitating factor (eg alcohol or caffeine) may suffice.

This may be indicated when:[4]

  • There is a very rapid pulse (greater than 150 beats per minute) and/or low blood pressure (systolic blood pressure less than 90 mm Hg).
  • There is loss of consciousness, severe dizziness, ongoing chest pain, or increasing breathlessness.
  • There is a complication of atrial fibrillation (AF), such as stroke, transient ischaemic attack (TIA), or acute heart failure.

Routine referral to a cardiologist should be considered when:

  • The person is young, eg less than 50 years of age.
  • Paroxysmal AF is suspected.
  • There is uncertainty regarding whether rate or rhythm control should be used.
  • Drug treatments that can be used in primary care are contra-indicated or have failed to control symptoms.
  • The person is found to have valve disease or left ventricular systolic dysfunction on echocardiography.
  • Wolff-Parkinson-White syndrome or a prolonged QT interval is suspected on the electrocardiogram.

Rate control may be started in primary care and is the preferred treatment when patients have persistent atrial fibrillation (AF), or are more than 65 years old, or have coronary artery disease, or have contra-indications for cardioversion or anti-arrhythmic drugs.

  • Ventricular rate control may be at least as effective as restoration of sinus rhythm in terms of survival and symptom control, especially in elderly patients.[1]
  • With rate control, the target ventricular rate (measured on an ECG or at the ventricular apex, but not the wrist) is below 80 beats per minute at rest and 90-115 on moderate exercise.
  • A heart rate-limiting calcium-channel blocker (e.g verapamil or diltiazem) or a beta-blocker are recommended as first-line therapy for control of the ventricular rate. Verapamil should not be combined with a beta-blocker because of the risk of heart block and asystole. Sotalol should not be used just for rate control because it is associated with an increased incidence of ventricular arrhythmias.[2]
  • Digoxin may control the resting heart rate, but rarely adequately controls heart rate during exertion and so should only be considered as monotherapy in predominantly sedentary patients. It may be added as a second-line therapy.
  • Often a combination of two drugs may be needed and, in this case, digoxin can be combined with either a rate-limiting calcium-channel blocker or a beta-blocker.

This is preferred in patients with paroxysmal atrial fibrillation (AF) and in patients with persistent AF who are symptomatic, younger than 65 years, presenting for the first time with lone AF or secondary AF or with congestive heart failure.[4] It should be started after specialist assessment.

  • Direct current (DC) cardioversion is safe with appropriate anticoagulation (thromboembolism in less than 1%) and effective in both AF (80-80% success rate) and atrial flutter (success rate over 95%).
  • Full anticoagulation is required if pharmacological or electrical cardioversion is considered. It should be in place for at least three weeks before and four weeks after the procedure, except when AF has existed for less than 48 hours.[3]
  • Indications for routine cardioversion include:
    • Recent-onset AF (but not always clear when it started)
    • No structural heart disease
    • Successful treatment of the precipitating cause eg thyrotoxicosis
    • Chest infection
    • Young age (but elderly are not excluded)
  • Indications for urgent cardioversion include acute AF with severe hypotension, heart failure, acute myocardial infarction or unstable angina.
  • It is unsuitable in structural heart disease, when thromboprophylaxis is contra-indicated, when AF has been present for >12 months, when there is an underlying cause that is inadequately treated (such as thyrotoxicosis) or previous attempts have failed.
  • Pharmacological cardioversion:[5] 
    • Flecainide and propafenone are recommended but should not be used in patients with structural heart disease, coronary heart disease, left ventricular dysfunction or severe left ventricular hypertrophy. Patients with structural heart disease are more susceptible to severe complications from pharmacological cardioversion.
    • Oral amiodarone is the drug of choice if there is structural heart disease or heart failure. It is effective in converting AF to normal sinus rhythm and is also the most effective in preventing relapse after cardioversion, but has significant side-effects and can enhance the anticoagulant effect of warfarin.
    • Recommended drugs for maintaining sinus rhythm are amiodarone, disopyramide, flecainide and propafenone.
  • A 'pill-in-the-pocket' strategy should be considered in 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 AF, and have a systolic blood pressure greater than 100 mm Hg and a resting heart rate above 70 beats per minute, and are able to understand how, and when, to take the medication:
    • In patients with symptomatic paroxysms (with or without structural heart disease, including coronary artery disease) a beta-blocker is first choice.
    • In patients with paroxysmal AF and no structural heart disease: if symptomatic suppression is not achieved with beta-blockers, either a Class Ic agent (eg flecainide or propafenone) or sotalol should be given. If suppression of symptoms is still not achieved, either amiodarone or referral for non-pharmacological intervention should be considered.
    • In patients with paroxysmal AF and coronary artery disease: if beta-blockers do not achieve symptomatic suppression, sotalol should be given. If suppression of symptoms is still not achieved, either amiodarone or referral for non-pharmacological intervention should be considered.
    • In patients with paroxysmal AF with poor left ventricular function: if beta-blockers do not adequately suppress paroxysms, either amiodarone or referral for non-pharmacological intervention should be considered.

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All patients with atrial fibrillation (AF) should have a formal stroke risk assessment with a validated tool such as CHA2DS2-VASc.[5] Thromboprophylaxis is recommended for all patients with AF except those at least risk, ie lone AF patients aged less than 65 years, or those with contra-indications to treatment.

  • Warfarin substantially reduces risk of stroke by about 70%. The INR should be kept between 2-3 to optimise the therapeutic effect and minimise the risk of bleeding. A lower INR target of 1.5-3.0 has been shown to be safe and effective in the over 75 year age group.
  • Dabigatran etexilate (Pradaxa®) is a thrombin inhibitor. 150 mg twice daily is more effective than warfarin in reducing the risk of stroke or systemic embolism, ischaemic stroke and vascular mortality:[6]
    • It does not require monitoring.
    • Compared with warfarin, overall risk of life-threatening bleeds is reduced but there is an increased risk of a GI bleed. This may be the
      result of a local effect on the GI mucosa
    • The National Institute for Health and Clinical Excellence (NICE) suggests it can be used (after consideration of risk:benefit) in patients with nonvalvular AF with one or more of the following risk factors - previous stroke, transient ischaemic attack (TIA) 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 or age 65 years or older with diabetes mellitus, coronary artery disease or hypertension.
    • It can also be used in those patients with a poorly controlled INR currently on warfarin.
    • Dabigatran 110 mg bd is appropriate for patients aged 80 years and above.
  • Rivaroxaban (Xarelto®) directly inhibits activated factor X (factor Sa). It is another alternative anticoagulant. The usual dose is 10 mg daily.[7]
    • It does not require monitoring.
    • The National Institute for Health and Clinical Excellence (NICE) suggests it can be used (after consideration of risk:benefit) in patients with nonvalvular AF 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.
    • It can also be used in those patients with a poorly controlled INR currently on warfarin.
  • Aspirin should not be used for stroke prevention in AF, as it is ineffective and no safer than warfarin; patients who are taking aspirin solely for this purpose should be reviewed.[8]
  • Percutaneous radiofrequency ablation is a treatment option for symptomatic patients with atrial fibrillation (AF) refractory to anti-arrhythmic drug therapy or where medical therapy is contra-indicated because of comorbidity or intolerance.
    • Radiofrequency ablation does not remove the need for anticoagulation or improve mortality.
    • AV node ablation is a very effective treatment for rate control but is permanent. It is a palliative procedure and can lead to pacemaker dependency.
    • Radiofrequency ablation of the atria can be performed via a catheter introduced through a femoral vein or by surgical radiofrequency ablation in patients undergoing concomitant open-heart surgery.[9]
  • Cryoablation or high-intensity focused ultrasound (HIFU) ablation may be used in the management of AF for patients undergoing concomitant open-heart surgery, eg mitral valve replacement or repair.[9][10]
  • Microwave ablation of the atria for patients with AF can be performed via a catheter introduced through a femoral vein or by surgical microwave ablation in patients undergoing concomitant open-heart surgery.[11]
  • Thoracoscopic epicardial radiofrequency ablation has been shown to be effective, at least in the short term.[12]
  • Atrial fibrillation (AF) increases risk of stroke six-fold (much more in patients with rheumatic heart disease), and becomes increasingly important as a risk factor for stroke with increasing age. Paroxysmal as well as persistent AF increases risk of stroke.
  • The risk of stroke is less in patients with no other structural heart disease ('lone AF').
  • AF can also precipitate acute heart failure and aggravate established heart failure.
  • Chronic atrial tachyarrhythmia may lead to cardiomyopathy.
  • AF is associated with an approximate doubling of the risk of premature death.
  • There may be implications for the patient's fitness to drive. Check with the Driver and Vehicle Licensing Agency (DVLA).
  • Atrial fibrillation (AF) is associated with reduced life expectancy in older patients.
  • People with AF have double the mortality and a five-fold higher risk of stroke than those without fibrillation.[4]
  • Prognosis depends on the patient's underlying medical condition.
  • Any atrial arrhythmia can cause a tachycardia-induced cardiomyopathy.
  • Smoking cessation: smoking is a risk factor for coronary heart disease as well as a precipitating factor for AF.
  • Alcohol moderation or avoidance: acute alcoholic intoxication or alcohol withdrawal may precipitate paroxysmal AF.
  • Diet: caffeine may induce paroxysmal AF in susceptible individuals.

Further reading & references

  1. Lip GY, Tse HF; Management of atrial fibrillation. Lancet. 2007 Aug 18;370(9587):604-18.
  2. The management of people with atrial fibrillation and flutter, New Zealand Guidelines Group, May 2005
  3. Lafuente-Lafuente C, Mahe I, Extramiana F; Management of atrial fibrillation. BMJ. 2009 Dec 23;339:b5216. doi: 10.1136/bmj.b5216.
  4. Atrial fibrillation; NICE CKS, August 2009
  5. Management of Atrial Fibrillation 2010 and Focused Update 2012; European Society of Cardiology (2012)
  6. Atrial fibrillation - dabigatran etexilate; NICE Technology Appraisal, March 2012
  7. Atrial fibrillation (stroke prevention) - rivaroxaban; NICE Technology Appraisal, May 2012
  8. RCPE UK Consensus Conference on 'Approaching the comprehensive management of Atrial Fibrillation: Evolution or revolution?', Royal College of Physicians of Edinburgh (RCPE), March 2012
  9. High-intensity focused ultrasound ablation for atrial fibrillation as an associated procedure with other cardiac surgery, NICE (2006)
  10. Cryoablation for atrial fibrillation in association with other cardiac surgery, NICE (2005)
  11. Microwave ablation for atrial fibrillation in association with other cardiac surgery, NICE Interventional Procedure Guideline (2005)
  12. Thoracoscopic epicardial radiofrequency ablation for atrial fibrillation, NICE Interventional Procedure Guideline (January 2009)

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Prof Cathy Jackson
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Last Checked:
13/06/2012
Document ID:
452 (v27)
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