• Admit (or refer) for urgent assessment and intervention if the person has any of the following:
• A rapid pulse (greater than 150 beats per minute) and/or low blood pressure (systolic blood pressure less than 90 mmHg).
• Loss of consciousness, severe dizziness, ongoing chest pain, or increasing breathlessness.
• A complication of atrial fibrillation (AF), such as stroke, transient ischaemic attack, or acute heart failure.
• Refer people with new-onset AF to a specialist in cardiology if:
• The person is young (for example less than 50 years of age).
• Paroxysmal AF is suspected.
• Rhythm control is the preferred treatment, or there is uncertainty regarding this (see Rate or rhythm control).
• Drug treatments for rate control or antithrombotic treatment that can be used in primary care are contraindicated.
• 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.
• Heart rate is difficult to control, or the person continues to have symptoms despite rate-control treatment (see Management after starting rate-control treatment).

The National Institute for Health and Clinical Excellence (NICE) makes no specific recommendations regarding referring people with atrial fibrillation (AF) from primary to secondary care. The following recommendations are inferred from the NICE guidance [NICE, 2006] or are based on expert opinion [NHS Scotland, 2005].

Admission

• Most people presenting with AF are not haemodynamically compromised. If the person is compromised, admission to hospital is needed for urgent intervention to prevent further deterioration.
• NICE states that the following people in AF are those at highest risk from haemodynamic instability:
• People with a ventricular rate greater than 150 beats per minute.
• Those with ongoing chest pain.
• After reviewing the evidence (three small studies), NICE concluded that rate-control drugs (such as beta-blockers and rate-limiting calcium-channel blockers) and pharmacological and electrical cardioversion are effective treatment options for the management of people presenting with haemodynamic instability.
• Usually, electrical cardioversion is the treatment of choice for people with haemodynamic instability, and amiodarone is only used when there is an unacceptable delay to cardioversion.

Referral

• Type of AF
• It may be difficult to categorize AF. For example, different types of AF are not mutually exclusive, and the person may have episodes of paroxysmal AF and occasional persistent AF. Specialist input may be needed to categorize the person on their most frequent presentation [Fuster et al, 2006a].
• Paroxysmal AF
• Paroxysmal AF requires antiarrhythmic drugs that are not usually started in primary care (such as amiodarone or sotalol).
• Advice given in the British National Formulary is that class I and III drugs (such as flecainide) should usually only be started by a specialist [BNF 57, 2009].
• Deciding between rhythm or rate control
• Some people with persistent AF will satisfy criteria for both rate and rhythm control (for example, older than 65 years of age but also symptomatic); therefore, specialists may consider additional investigations (echocardiography) and take into account the person's comorbidities before deciding on the most appropriate treatment.
• Failed primary care treatment, electrocardiogram abnormality, or cardiac dysfunction
• If the person with AF has persistent symptoms despite maximum treatment given in primary care, a specialist may consider the use of drugs that are not routinely started in primary care (such as amiodarone or sotalol).
• In addition to drug treatment, a specialist may consider further interventions depending on the person's age, severity of symptoms, type of AF, and presence of cardiac dysfunction (for example such interventions as pulmonary vein isolation, pacemaker therapy, arrhythmia surgery, catheter ablation, or use of atrial defibrillators).