Introduction to Atrial Fibrillation
This section covers the clinical presentation, classification and origin of AF, and its management
In this section:
Clinical presentation of AF
- In AF the atria beat irregularly and often rapidly, as a result, the ventricles cannot adequately fill with blood, cardiac output is reduced and a thrombus can form from stagnant blood in the fibrillating left atrium
- AF can present with a variety of symptoms (listed below), which can be mild to severe in severity, but some patients have no symptoms at all:
- Fatigue
- Palpitations
- Syncope/dizziness
- Angina/chest pains
- Dyspnoea/breathlessness
- Stroke/transient ischaemic attack
- AF has a heterogeneous clinical presentation, occurring in the presence or absence of detectable heart disease or related symptoms; therefore, clinical guidelines feature recommendations for appropriate classification/definition
Classification of AF
- AF is classified into five categories, as summarized in the Table below:
Classification | Clinical presentation |
---|---|
First diagnosed AF |
|
Paroxysmal |
|
Persistent |
|
Long-standing persistent |
|
Permanent |
|
Origin of AF: NVAF or VAF?
- Definitions of NVAF and VAF remain a matter of debate; current definitions are summarized in the table below
- Classification of AF as VAF or NVAF facilitates identification of risk for thromboembolic events and the need for a specific antithrombotic strategy3
Investigation
Because AF is frequently intermittent and can be asymptomatic or associated with non-specific symptoms, detection and diagnosis can be difficult.
Investigations for the clinical evaluation of AF include5
- ECG: Upon detection of an irregular pulse, an ECG should be performed in all cases of suspected AF, whether symptomatic or not
- With suspected paroxysmal AF, a 24-hour ambulatory ECG monitor should be used if asymptomatic episodes are suspected or if episodes are <24 hours apart
- An event recorder ECG should be used where symptomatic episodes are >24 hours apart
- Echocardiograms: to assess the dimensions of the left atrium and left ventricle and left ventricular wall thickness and function, and to exclude occult valvular or pericardial disease and hypertrophic cardiomyopathy
- TTE: performed in patients with AF when:
- A baseline echocardiogram is important for long-term management
- A rhythm-control strategy that includes cardioversion (electrical or pharmacological) is being considered
- There is a high risk or a suspicion of underlying structural/functional heart disease that influences subsequent management
- Refinement of clinical risk stratification for antithrombotic therapy is needed
- TEE: performed in patients with AF when:
- TTE demonstrates an abnormality (such as valvular heart disease) that warrants further specific assessment
- TEE-guided cardioversion is being considered
- TTE: performed in patients with AF when:
- Blood tests are important for first episodes of AF and when the ventricular rate is difficult to control – these include tests of thyroid, renal and hepatic function
Management approaches
- Subsequent sections consider how management approaches differ according to the type of AF and specific patient characteristics.
- In general, management of patients with AF involves three main objectives, which are not mutually exclusive:1
- Optimized stroke prevention
- Symptom control with rate or rhythm control
- Management of cardiovascular risk factors/co-morbidities
- To find out more about the potentially serious consequences of AF and the critical nature of its management, click on the link to next section below
- In general, management of patients with AF involves three main objectives, which are not mutually exclusive:1
References
- Hindricks G, Potpara T, Dagres N et al. 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation developed in collaboration with the European Association of Cardio-Thoracic Surgery (EACTS). Eur Heart J 2020: doi:10.1093/eurheartj/ehaa612. Return to content
- January CT, Wann LS, Alpert JS et al. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol 2014;64:e1–76. Return to content
- Fauchier L, Philippart R, Clementy N et al. How to define valvular atrial fibrillation? Arch Cardiovasc Dis 2015;108:530–539. Return to content
- January CT, Wann LS, Calkins H et al. 2019 AHA/ACC/HRS focused update of the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society in collaboration with the Society of Thoracic Surgeons. Circulation 2019;140:e125–e151. Return to content
- National Institute for Health and Care Excellence. Atrial fibrillation: management. Clinical guideline [CG180]. 2014. Available at: https://www.nice.org.uk/guidance/cg180 [accessed 20 November 2020]. National Institute for Health and Care Excellence. Atrial fibrillation: management. Clinical guideline [CG180]. 2014. Available at: https://www.nice.org.uk/guidance/cg180 [accessed 20 November 2020]. Return to content