Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. It is described as an irregular heart rhythm that is often abnormally fast (World Heart Federation 2015).The NICE commissioning guide on anticoagulation therapy stated that the prevalence of AF in England in 2011 was likely to be close to 2.0%, which equated to about 835,000 people living with AF. Although AF can affect adults of any age, prevalence in the population increases as people get older. A UK study of 6286 adults found the prevalence ranged from 0.2% in people aged between 45 and 54, to 14.0% in people aged over 85 years (Davis et al. 2012). The prevalence of AF is reported to be greater in men. For example, in the Rotterdam study the overall prevalence in men was 6.0%, compared with 5.1% for women, and prevalence across all assessed age groups was also higher in men (Heeringa et al. 2006).
AF can cause morbidity and mortality, either directly or due to AF being a major risk factor for stroke (Wolf et al. 1991). Davis et al. (2012) found that people with AF had a higher prevalence of heart failure, myocardial infarction, hypertension, angina and diabetes. AF is associated with a 5‑fold increase in the risk of stroke (Wolf et al. 1991). Each year AF accounts for between 25,000 and 35,000 strokes in the UK (Allaby 2014). The risk of stroke can be reduced if suitable treatment is given after diagnosis of AF. For example, it has been shown that adjusted‑dose warfarin can reduce the risk of stroke by 62% (Hart et al. 1999).
The Framingham Heart Study enrolled 5209 people aged 28 to 62 to investigate the consequences of cardiovascular disease. To assess the impact of AF, Benjamin and colleagues analysed 40 years of follow‑up data from the study. After adjusting the mortality risk to account for pre‑existing cardiovascular conditions, the risk of death in people of all ages with AF was 50% greater in men and 90% greater in women, compared with those without AF (Benjamin et al. 1998).
AF can be classified into different categories, according to the frequency and duration of the cardiac arrhythmia:
Paroxysmal AF is an arrhythmia that occurs occasionally and then stops. Episodes can last from minutes to days before the heart spontaneously returns to normal rhythm.
Persistent AF lasts for longer than 7 days and does not resolve without treatment. Normal rhythm can be achieved with medication, electric shock treatment or ablation.
Permanent AF causes people to be in AF at all times. Normal heart rhythm cannot be maintained even with medication, electrical shock treatment or ablation (NHS Choices 2013; Camm et al. 2010).
AF may have non‑specific symptoms or no symptoms at all. It is often only diagnosed following serious complications including stroke, thromboembolism and heart failure. The NICE guideline on atrial fibrillation states that opportunistic screening of people at high risk of AF can detect the condition before serious complications develop. Risk factors for AF include:
high blood pressure
diabetes (NHS Choices 2013).
Case finding in high risk populations through the use of an electrocardiogram (ECG) recording can help to identify people with undetected AF. Single time‑point screening using pulse palpitation or ECG in people aged 65 years and over, found that 1.4% of people tested had previously undiagnosed AF, and 67% of these people were at high risk of stroke (Lowres et al. 2013).
Taking repeat ECG recordings continuously over a 24‑hour period or recording events over several days can increase the probability of detecting an arrhythmia. This can be achieved using portable ECG recorders, and different types of recorder are available.