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Atrial Fibrillation (AF)

NICE guideline [NG196] Atrial fibrillation: diagnosis and management. Last updated: Jun 2021.

Background Information

AF is a type of supraventricular tachyarrhythmia, characterised by uncoordinated atrial contractions and therefore irregular ventricular contractions.

AF can also manifest with slow or normal ventricular rates, especially if on rate control medications. 

  • Paroxysmal AF: AF that self-terminates, lasts <7 days (but usually within 48 hours)
  • Persistent AF: AF episode lasts >7 days or requires cardioversion to restore sinus rhythm
  • Permanent AF: rhythm control strategy is abandoned, and AF is accepted as ongoing

Risk factors for chronic AF: [ref, ref]

  • Advancing age
  • Causes of left atrial dilation
    • Mitral valve disease
    • Heart failure
  • Obstructive sleep apnoea
  • Hypertension
  • Metabolic syndrome
  • CKD

Risk factors for reversible / transient AF episodes: [ref, ref]
  • Any acute illness or infection (e.g. sepsis, pneumonia)
  • Acute alcohol intoxication (holiday heart syndrome)
  • Thyrotoxicosis
  • Post-operative state

Major complications of AF: [ref]
  • Embolic stroke (ischaemic) - most important complication
  • Systemic thromboembolism (renal infarct, splenic infarct, mesenteric ischaemia)
  • Heart failure

Pulmonary embolism can occur if there is an intracardiac shunt (e.g. atrial septal defect)

Diagnosis

10-40% of patients with AF are asymptomatic. [ref]

Symptoms are non-specific:
  • Palpitations - typical description is 'irregular heartbeat', 'fluttering', 'pounding'
  • Exertional dyspnoea
  • Exercise intolerance
  • Fatigue

Typical examination findings of AF:
  • Irregularly irregular pulse
  • Variable 1st heart sound intensity

Features of the associated cause can also be present (e.g. mitral stenosis, heart failure).

To accurately comment on the pulse rate in AF at the bedside:

  • Palpate the radial pulse for a full 60 sec
  • Auscultate the apex for a full 60 sec (apical pulse method) - preferred

1st line and confirmatory test: 12-lead ECG
  • ECG is always required to confirm the diagnosis
  • If paroxysmal AF is suspected or the initial ECG is inconclusive but AF is suspected clinically → Holter monitor for 24 hours

Additional investigations if AF is confirmed:
  • Transthoracic echocardiography (to assess for structural heart disease and cardiac function)
  • Blood tests (FBC, U&E, LFT, TFT, HbA1c)

  • Irregularly irregular rhythm
  • Invisible P waves
  • Narrow QRS (unless aberrancy is present)
  • Heart rate can vary

Management

Follow peri-arrest tachycardia management.

In short:
  • Unstable → synchronised DC cardioversion
  • Stable
    • <48 hours → rate or rhythm control
    • >48 hours → rate control with beta blockers

Commonly used beta blockers in acute fast AF are:

  • Bisoprolol - oral only
  • Metoprolol - both oral and IV routes are possible
  • Carvedilol - preferred if there is comorbid heart failure

There are 2 main aspects of the long-term management of AF.

Typically, those with no symptoms with an in-range or even slow heart rate might not necessarily require rate or rhythm control. In an exam question, if you are made to choose between rate control vs anticoagulation, always choose anticoagulation (provided that CHA2DS2VSc score indicates anticoagulation is necessary), as reducing risk of stroke is a lot more important.

There are 2 main approaches to choose from 1) rate and 2) rhythm control
 

Rate control is typically 1st line for most patients

A few exceptions where rhythm control is preferred as 1st line (over rate control):
  • New onset AF (<48 hours onset)
  • Heart failure secondary to AF
  • Presence of a reversible cause
  • Rate control is not inappropriate or inadequate
  • AF with atrial flutter deemed suitable for ablation strategy

New onset AF (<48 hours) is the most important indication to choose rhythm control over rate control in both exams and in practice. Realistically, the choice between rate and rhythm control is a shared decision made between the patient and the doctor, taking numerous factors into account.

1st line: monotherapy of standard cardioselective beta blocker or non-DHP CCB (diltiazem / verapamil)
  • If AF + heart failure: beta blocker is preferred
  • Digoxin monotherapy is a 1st line alternative in those who do little physical activity

2nd line: dual therapy from standard beta blocker or diltiazem or digoxin
 

Do not offer amiodarone for long-term rate control. 

There are 3 main options for rhythm control:
  • Electrical rhythm control
  • Pharmacological rhythm control
  • Cardiac catheterisation interventions - usually last line

Electrical cardioversion is generally preferred (if rhythm control is opted for), especially if AF persisted for >48 hours and if rapid cardioversion is needed
  • However many clinical and patient factors can influence the decision of which rhythm control method to opt for.
  • In exams, apart from an unstable patient needing immediate cardioversion, it is uncommon for the question to ask the student to choose between methods of rhythm control. Instead, it is more common for the question to test one's knowledge on individual cardioversion methods such as which drug to use and precautions. 

If AF onset is <48 hours → cardioversion can be carried out now with prior heparin loading

If AF onset is >48 hours, precautions must be taken:
  • Give 3 weeks of anticoagulation prior to conversion, or
  • Perform TOETransoesophageal echocardiography to exclude a left atrial thrombus → then give heparin and cardiovert now

The reason extra precautions are needed prior to cardioversion in those with AF osnet >48 hours is because after 48 hours it is likely that a left atrial thrombus has formed. If the patient is cardioverted immediately without any anticoagulation, the cardioversion is likely to dislodge the left atrial thrombus and cause an embolic stroke.

Rhythm control option Sub-options Recommendations
Electrical n/a Synchronised DC cardioversion
  • Under sedation or GAGeneral anaesthesia, and
  • Under precautions as described above

Consider amiodarone starting 4 weeks before and continuing for up to 12 months after electrical cardioversion to maintain sinus rhythm
Pharmacological Cardioversion (immediate restoration of sinus rhythm)
  • 1st line: flecainide
  • If there is ischaemic / structural heart disease: amiodarone
Long-term maintenance therapy
  • 1st line: standard cardioselective beta blocker
  • 2nd line: dronedarone
  • Consider amiodarone in heart failure / left ventricular impairment

Consider pill in the pocket / no drug treatment if infrequent paroxysms and few symptoms or induced by known precipitants
Cardiac catheterisation interventions Left atrial ablation (pulmonary vein isolation)
  • Requires 4 weeks of anticoagulation prior, and at least 2 months of anticoagulation after
Pace and ablate Pacemaker implanted before AV node ablation
  • For those with symptomatic AF thought to be caused by uncontrolled ventricular rate
 

The drug class of choice to reduce stroke risk in AF is anticoagulants (not antiplatelets), the decision is mainly influenced by balancing the risk of stroke and risk of bleeding.

Assessing the need for anticoagulation in AF is very important, all patients with AF should be assessed (even after a single AF episode or paroxysmal AF).

The CHA2DS2VSc score is recommended to assess the risk of stroke in AF:
  • Male
    • Score 1: consider anticoagulation
    • Score ≥2: offer anticoagulation
  • Female
    • Score ≥2: offer anticoagulation
 
CHA2DS2VSc score component Score
Congestive heart failure 1
Hypertension 1
Age (65-74 y/o) 1
Age (≥75 y/o) 2
Diabetes 1
Stroke / TIATransient ischaemic attack / thromboembolism 2
Vascular disease (IHDIschaemic heart disease, PADPeripheral arterial disease) 1
Sex (female) 2
 

NICE recommends the ORBIT score

  • But there are no recommendations on using the score to guide the decision of whether to give anticoagulation or not
  • Clinical judgement should be used, while taking into account the patient's wishes

1st line for most patients: DOACsDirect oral anticoagulants (apixaban / rivaroxaban / dabigatran / edoxaban)
  • In the context of renal impairment, apixaban is preferred
  • Warfarin is 1st line in valvular AF (i.e. AF with a mechanical heart valve or moderate to severe mitral stenosis)

2nd line: warfarin

If anticoagulation is not appropriate: left atrial appendage occlusion
 

Do not withhold anticoagulation solely because of a person's age or their risk of falls.

References

NICE guideline [NG196] Atrial fibrillation: diagnosis and management. Last updated: Jun 2021.
Author: Adams Lau
Reviewer:
Last edited: 17/09/25