Introduction to and classification of atrial fibrillation

Atrial fibrillation is a recurrent atrial tachyarrhythmia that is estimated to have a prevalence from 2 to 4% in developed countries, such as AustraliaNHFA CSANZ Atrial fibrillation guideline working group, 2018. Worldwide, in adults, atrial fibrillation is the most common sustained cardiac arrhythmiaHindricks, 2021. Atrial fibrillation is often asymptomatic and the risk increases with age. The majority of patients who develop atrial fibrillation have identifiable cardiovascular risk factors, and associated comorbidities. Lifestyle modifications are essential for patients with atrial fibrillation (eg weight management, alcohol reduction or cessation, treatment of obstructive sleep apnoea).

Patients with atrial fibrillation have a higher mortality rate than the general population—most of the mortality is due to thromboembolic complications (such as stroke) or from noncardiac causes (such as chronic obstructive pulmonary disease or kidney disease).

Atrial fibrillation is classified according to clinical pattern, with patients sometimes progressing from one pattern to another. At first diagnosis, consider differentiating atrial fibrillation into one of the following classifications:

  • paroxysmal atrial fibrillation—when episodes are self-terminating, usually within 48 hours, but can continue for up to 7 days. Atrial fibrillation that is cardioverted (rhythm control) within 7 days is considered paroxysmal
  • persistent atrial fibrillation—when episodes last longer than 7 days. Atrial fibrillation that is cardioverted (rhythm control) after 7 days is considered persistent
  • longstanding persistent atrial fibrillation—when continuous atrial fibrillation lasts for 1 year or longer, and it is decided to use rhythm control
  • permanent atrial fibrillation—when rhythm control is not used because remaining in atrial fibrillation is accepted by the patient. If rhythm control is later undertaken in these patients, the atrial fibrillation would be reclassified as longstanding persistent atrial fibrillation.

Classifying atrial fibrillation in conjunction with the patient’s symptoms and the clinical context can influence subsequent management. For example, all types of atrial fibrillation are associated with a risk of stroke and thromboembolism, but this risk is greater in patients with persistent rather than paroxysmal atrial fibrillationGanesan, 2016Hindricks, 2021 (see Overview of prevention of thromboembolic events in atrial fibrillation for further information).

Atrial flutter may occur as a solitary atrial arrhythmia, with similar management to atrial fibrillation; a significant number of patients with atrial flutter may also develop atrial fibrillationHindricks, 2021.

The management of atrial fibrillation and atrial flutter consists of 3 major components: