Classification of Atrial Fibrillation

Atrial fibrillation (AF) is classified according to:

Episodes
Valvular disease (mitral stenosis or mechanical valve)

An episode is a continuous run of AF.

Patients most commonly perceive an AF episode as palpitations (awareness of rapid heartbeat).

10 % of patients have no symptoms during AF episodes (silent AF).

One patient may have 3 episodes of atrial fibrillation within 24 hours (episodes lasting, for example, 10 min, 20 min, and 50 min).

Another patient may have an AF episode once per month (each episode lasting, for example, approximately 3 days).

Some episodes may be symptomatic and others asymptomatic in the same patient.
If the patient is not currently experiencing an AF episode, they are in normal sinus rhythm.

Valvular AF means that the patient has AF and valvular disease, specifically:

mitral stenosis (moderate or severe) or
a mechanical valve

Every patient with valvular AF, regardless of the CHA₂DS₂-VA score,

must receive anticoagulation therapy: warfarin, not a NOAC.

Illustration of valvular atrial fibrillation in the presence of a mechanical heart valve and moderate to severe mitral stenosis.

Classification of Atrial Fibrillation According to Episodes and Valvular Disease
Newly diagnosed AF	Refers to the date when AF was first documented on ECG, regardless of how long the patient has had symptoms. 10 % of patients are asymptomatic during AF episodes. For example: the patient has had AF episodes for 2 years and does not perceive them.
Paroxysmal AF	An AF episode lasts less than 7 days. Episodes usually terminate within 48 hours. The AF episode terminates spontaneously or with intervention: pharmacological or electrical cardioversion. The treatment strategy is rhythm control (maintain sinus rhythm): pharmacological therapy, electrical cardioversion, or ablation.
Persistent AF	An AF episode lasts more than 7 days. The episode usually does not terminate spontaneously, and intervention is required for termination: pharmacological or electrical cardioversion. The treatment strategy is rhythm control (maintain sinus rhythm): pharmacological therapy, electrical cardioversion, or ablation.
Long-standing persistent AF	An AF episode lasts more than 12 months. The treatment strategy remains rhythm control (maintain sinus rhythm): pharmacological therapy, electrical cardioversion, or ablation.
Permanent AF	The AF episode lasts at least 6 months. Repeated attempts to restore sinus rhythm have failed. The physician, in agreement with the patient, no longer attempts to restore sinus rhythm. The principle applies that every patient should have at least one attempt to restore sinus rhythm: pharmacological or electrical cardioversion or ablation. The treatment strategy is rate control (maintain AF ventricular rate <100/min): pharmacological therapy.
Valvular AF	Refers to any AF in a patient who has: a mechanical valve or mitral stenosis (moderate or severe) Regardless of the CHA₂DS₂-VA score, these patients must always receive warfarin, not a NOAC.

NOAC – Non-vitamin K Oral Anticoagulant (Dabigatran, Rivaroxaban, Apixaban, Edoxaban)

In clinical practice, AF is most commonly classified as newly diagnosed (date when AF was first documented on ECG), paroxysmal, persistent, permanent, and valvular. Documentation in the patient record may appear, for example, as follows:

Paroxysmal AF (diagnosed 2 April 2022)
Persistent AF (diagnosed 4 April 2020)

Diagram of atrial fibrillation types illustrating paroxysmal, persistent, and permanent atrial fibrillation compared with sinus rhythm over time.

Classification of Atrial Fibrillation

Class

Atrial fibrillation is classified according to episodes and valvular disease into:

Newly diagnosed AF (date of first documented AF on ECG)
Paroxysmal AF
Persistent AF
Permanent AF
Valvular AF

(mechanical valve or mitral stenosis – moderate or severe)

AF causes atrial remodelling; therefore, AF gradually progresses:

paroxysmal → persistent → permanent; this process takes years.

The progression of AF can be slowed if the patient initiates adequate pharmacological therapy and risk factor modification.

With adequate treatment (pharmacological therapy, electrical cardioversion, ablation) and risk factor modification, improvement of AF may occur: persistent → paroxysmal AF → sinus rhythm. Despite comprehensive treatment, complete elimination of AF is sometimes not achieved.

Atrial Fibrillation – Prevalence by Episode Type
AF Type	% of cases
Paroxysmal	50 %
Persistent	30 %
Permanent	20 %

Paroxysmal AF is the most common form of AF – it accounts for approximately 50 % of all cases.

Paroxysmal AF means that episodes last less than 7 days (most commonly resolve within 24 hours).

This definition is very broad – paroxysmal AF may present with episodes of varying duration and frequency.

Examples of paroxysmal AF:

Short episodes lasting only a few minutes, occurring once every few months.
Longer episodes lasting several hours, which may recur several times per day.