---
title: Atrial flutter
description: What atrial flutter is, how it differs from atrial fibrillation, how it is recognised, which treatment approaches clinical guidelines describe and when urgent help is needed.
type: disease
preset: atrial-flutter
aliases:
  - AFL
  - typical atrial flutter
  - atypical atrial flutter
  - CTI-dependent atrial flutter
sources:
  - tier: guideline
    org: minzdrav-rf
    title: Фибрилляция и трепетание предсердий
    year: 2025
    doi: 10.15829/1560-4071-2025-6668
    url: https://cr.minzdrav.gov.ru/view-cr/382_2
  - tier: guideline
    org: esc
    title: 2019 Рекомендации ESC по лечению пациентов с наджелудочковыми тахикардиями
    year: 2020
    doi: 10.15829/1560-4071-2020-3864
    url: https://doi.org/10.15829/1560-4071-2020-3864
  - tier: guideline
    org: esc
    title: 2024 ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS
    year: 2024
    doi: 10.1093/eurheartj/ehae176
    url: https://doi.org/10.1093/eurheartj/ehae176
  - tier: reference
    org: msd-manuals
    title: Atrial Flutter
    year: 2024
    url: https://www.msdmanuals.com/professional/cardiovascular-disorders/specific-cardiac-arrhythmias/atrial-flutter
  - tier: reference
    org: msd-manuals
    title: Atrial Fibrillation and Atrial Flutter
    year: 2025
    url: https://www.msdmanuals.com/home/heart-and-blood-vessel-disorders/abnormal-heart-rhythms/atrial-fibrillation-and-atrial-flutter
sources_checked: 2026-10-12
review: null
---

Atrial flutter (AFL) is a rhythm disorder in the group of supraventricular tachyarrhythmias in which the atria are activated at a rate of 250–350 per minute. It is caused by an electrical impulse that travels in a large closed loop (macro re-entry) around an obstacle in the atrium, usually involving the tricuspid valve.<Cite n={1} /> This is what sets flutter apart from [atrial fibrillation](../atrial-fibrillation/): in fibrillation the electrical activity of the atria is chaotic, while in flutter it is coordinated.<Cite n={[1, 5]} /> Flutter is much less common than fibrillation, but their causes and effects on the circulation are similar.<Cite n={4} />

<Diagram name="atrial-flutter">
  <p slot="normal">
    Normally each heartbeat begins with an impulse from the <Structure id="sa-node">sinus node</Structure>: it activates the atria and then passes through the <Structure id="av-node">atrioventricular (AV) node</Structure> to the ventricles.<Cite n={5} /> The usual heart rate is about 60–100
    beats per minute.<Cite n={5} />
  </p>
  <p slot="disease">
    In typical flutter the impulse circles in the <Structure id="right-atrium">right atrium</Structure> around the ring of the <Structure id="tricuspid-valve">tricuspid valve</Structure>, more often counterclockwise:
    down the free wall, through the isthmus between the <Structure id="inferior-vena-cava">inferior vena cava</Structure> and the valve ring (the
    cavotricuspid isthmus) and up the septum.<Cite n={[1, 2, 4]} /> The atria are usually activated
    about 300 times a minute; the AV node cannot conduct every impulse, and most often every second
    one reaches the ventricles — about 150 a minute (shown slowed down).<Cite n={4} />
  </p>
</Diagram>

## Why it happens

<Patient>

For the arrhythmia to start and keep going, it needs a "trigger" impulse and an area of atrial tissue that sustains it. Most often flutter develops when the walls of the atria have already been remodelled.<Cite n={1} /> Heart valve disease and high blood pressure make the atria enlarge, and this makes flutter and fibrillation more likely.<Cite n={5} /> Flutter is more common in older people and in people with heart disease, but it can also occur without it.<Cite n={5} />

The doctor will always look for causes that can be corrected: fever, low blood potassium, too much thyroid hormone, emotional stress, alcohol, high blood pressure, diabetes, obesity, worsening heart failure.<Cite n={1} />

Flutter and fibrillation often occur in the same person, and fibrillation is fairly common after flutter ablation.<Cite n={[2, 4]} />

</Patient>

<Student>

The Russian Ministry of Health guideline uses the H. Wells classification with two types of AFL. Typical AFL (type I) is seen in 90% of patients: the macro re-entrant wave travels around the tricuspid valve counterclockwise (most often) or clockwise (much less often) and must pass through the cavotricuspid isthmus (CTI).<Cite n={1} /> In counterclockwise typical AFL the CTI forms the lower boundary of the circuit: activation runs down the free wall of the right atrium (RA), through the CTI and up the right side of the interatrial septum.<Cite n={2} />

Atypical AFL (type II) covers all other atrial macro re-entrant circuits that do not involve the CTI; in the ESC guideline the terms "atypical AFL" and "non-CTI-dependent macro re-entrant tachycardia" are interchangeable.<Cite n={[1, 2]} /> The substrate can be atrial suture lines and patches after surgical repair of congenital defects, or areas of "electrical silence" in the RA free wall, probably related to fibrosis; atypical AFL also often arises as a consequence of catheter ablation of atrial fibrillation (AF).<Cite n={2} />

By course, AF/AFL is classified as first diagnosed, paroxysmal (self-terminating, in most cases within 48 hours; some paroxysms last up to 7 days), persistent, long-standing persistent (more than 1 year when a rhythm-control strategy has been chosen) and permanent.<Cite n={1} />

</Student>

<HeartModel highlight={['right-atrium', 'tricuspid-valve']} />

## Symptoms

<Patient>

How a person feels depends mainly on how fast the ventricles beat and on any underlying heart disease.<Cite n={4} /> If the pulse is regular and below 120 beats per minute, there may be few or no symptoms; a faster or irregular pulse usually causes palpitations.<Cite n={4} /> In flutter the pulse is usually fast and can be regular or irregular.<Cite n={5} />

When the heart pumps less blood, chest discomfort, shortness of breath, weakness and fainting may appear.<Cite n={4} /> Heaviness in the chest, poor sleep and sleepiness can also occur.<Cite n={1} />

</Patient>

<Student>

With a ventricular rate below 120 per minute and a regular rhythm there are likely to be few or no symptoms; faster rates and variable AV conduction usually cause palpitations, and reduced cardiac output causes symptoms of haemodynamic compromise.<Cite n={4} /> Close inspection of the jugular venous pulse shows flutter waves.<Cite n={4} />

Besides symptoms related to the fast heart rate and loss of atrial systole, symptoms of reversible left ventricular systolic dysfunction and tachycardiomyopathy are not uncommon.<Cite n={2} />

</Student>

## How it is diagnosed

<Patient>

The diagnosis is made with an [electrocardiogram](../../diagnostic/ecg/) (ECG).<Cite n={[4, 5]} /> It shows rapid, identical flutter waves, which in the typical form look like the teeth of a saw.<Cite n={[1, 4]} /> If every second impulse reaches the ventricles, flutter can be missed on the ECG; the doctor can then briefly slow conduction to the ventricles so that the waves become visible.<Cite n={[2, 4]} />

An ultrasound of the heart ([echocardiography](../../diagnostic/echocardiography/)) is done to assess the valves and look for blood clots in the atria.<Cite n={[1, 5]} /> A blood test shows whether the thyroid gland is overactive.<Cite n={[1, 5]} />

</Patient>

<Student>

ECG criteria for AFL: a regular atrial rhythm (F waves with a cycle length under 240 ms) at 250–350 per minute with equal or varying RR intervals; conduction to the ventricles is usually in a fixed ratio from 4:1 to 2:1, rarely 1:1; in typical AFL the F waves have a sawtooth pattern, most obvious in the inferior leads (II, III, aVF).<Cite n={1} /> In counterclockwise AFL the F waves are negative in the inferior leads and positive in V1.<Cite n={2} />

With 2:1 AV conduction the diagnosis of AFL may not be obvious on the surface ECG.<Cite n={2} /> Carotid sinus massage or pharmacological AV nodal blockade (for example with adenosine) can increase AV block and expose the flutter waves, but does not usually terminate AFL.<Cite n={4} /> Adenosine can speed AV conduction up to 1:1 and trigger AF, so when the diagnosis is unclear it is given in an intensive care setting.<Cite n={2} />

</Student>

## How it is treated

<Patient>

Treatment has three aims: to slow the ventricles, to restore the normal rhythm and to protect against blood clots.<Cite n={4} />

Slowing the pulse with tablets is harder in flutter than in fibrillation. So for a first episode the rhythm is often restored electrically: with a shock (cardioversion) or with rapid pacing of the atria through an electrode.<Cite n={4} /> In flutter, cardioversion works more often than in fibrillation.<Cite n={2} /> If flutter has seriously disturbed the circulation, the rhythm is restored as an emergency.<Cite n={[1, 2]} />

Some medicines used to restore the rhythm slow the flutter circuit itself, and then every impulse can get through to the ventricles — the pulse becomes much faster.<Cite n={[2, 4]} /> So these medicines are not used without medicines that slow conduction to the ventricles, and the doctor chooses them.<Cite n={2} />

The main way to get rid of typical flutter is catheter ablation. Using a catheter passed into the heart, a line that the impulse cannot cross is made in the isthmus between the inferior vena cava and the tricuspid valve.<Cite n={[1, 4, 5]} /> It is offered if medicines have not helped, or straight away, taking the patient's preferences into account.<Cite n={1} /> Ablation is the most effective way to keep a normal rhythm, and flutter rarely returns after it, but atrial fibrillation may appear over time.<Cite n={2} /> If ablation is not suitable or the person does not want it, the heart rate is controlled with medicines.<Cite n={2} />

Blood clots can form in the atria.<Cite n={4} /> If they travel in the bloodstream to the vessels of the brain, an ischaemic stroke develops.<Cite n={1} /> So the decision about medicines that reduce blood clotting (anticoagulants) follows the same rules as in fibrillation: the doctor assesses the risk with a special score.<Cite n={[1, 2, 4]} /> This protection is also needed before a planned restoration of the rhythm.<Cite n={[1, 3]} />

</Patient>

<Student>

Treatment of AFL includes ventricular rate control, rhythm control and prevention of thromboembolism.<Cite n={4} /> In haemodynamic instability synchronised electrical cardioversion is recommended (ESC I B; the Russian Ministry of Health guideline: emergency cardioversion for severe haemodynamic compromise).<Cite n={[1, 2]} />

For ventricular rate control the Russian Ministry of Health guideline names beta-blockers, cardiac glycosides, non-dihydropyridine calcium channel blockers, or a combination of a beta-blocker and a cardiac glycoside; the doctor chooses the specific drug.<Cite n={1} /> The ESC notes that the target ventricular rate is particularly hard to reach in AFL, and that electrical cardioversion is more often effective than in AF and needs less energy.<Cite n={2} /> Rapid and overdrive atrial pacing is recommended to terminate AFL but not AF; in patients with an implanted pacemaker or implantable cardioverter-defibrillator (ICD) the ESC recommends overdrive atrial pacing (I B).<Cite n={[1, 2]} />

Class IC antiarrhythmic drugs should not be used without drugs that slow AV conduction, because slowing of the flutter can lead to 1:1 AV conduction.<Cite n={2} /> The "pill-in-the-pocket" approach is not recommended for paroxysmal AFL.<Cite n={1} />

Catheter ablation of the CTI with bidirectional conduction block is recommended in typical AFL when antiarrhythmic therapy is ineffective, or as first-line treatment taking the patient's preferences into account, whatever the form of AFL.<Cite n={1} /> The ESC recommends catheter ablation for all patients with symptomatic, recurrent episodes of CTI-dependent AFL (I A) and suggests considering it after the first symptomatic episode of typical AFL (IIa B).<Cite n={2} /> Ablation is the most effective method for maintaining sinus rhythm, better than the antiarrhythmic drug it was compared with; with confirmed stable bidirectional block the recurrence of the tachyarrhythmia is under 10%, but the long-term risk of AF rises.<Cite n={2} /> Ablation of non-CTI-dependent AFL is done in expert centres (ESC I B), and according to the Russian Ministry of Health guideline with non-fluoroscopic navigation mapping.<Cite n={[1, 2]} />

According to the MSD Manual, the probability of thromboembolism in isolated AFL is thought to be about half that in AF, but many patients have or will develop AF, and anticoagulation guidelines make no distinction between AFL and AF.<Cite n={4} /> ESC 2019: anticoagulation as in AF is recommended for AFL with concomitant AF (I B); in AFL without AF it should be considered, but the threshold for starting it has not been established (IIa C).<Cite n={2} /> ESC 2024: oral anticoagulation is recommended in AFL at elevated thromboembolic risk (I B), and therapeutic anticoagulation before scheduled cardioversion of AF and AFL (I B).<Cite n={3} /> The Russian Ministry of Health guideline requires assessing risk with the CHA2DS2-VASc score in non-valvular AF/AFL and recommends the same anticoagulation scheme for cardioversion of AFL as for AF.<Cite n={1} />

</Student>

## When to call an ambulance

When the ventricles beat very fast, especially in older people and people with heart disease, heart failure or chest pain can develop, and very rarely shock with very low blood pressure.<Cite n={5} /> If sensations of a fast or irregular heartbeat, shortness of breath or discomfort behind the breastbone are new, more frequent or getting worse, the Russian Ministry of Health guideline advises seeking urgent help, ideally by calling an ambulance.<Cite n={1} /> Call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK) if palpitations come with chest pain or discomfort, severe shortness of breath, fainting or a feeling that you are about to faint.<Cite n={[1, 4, 5]} />

Flutter can lead to a stroke.<Cite n={[1, 5]} /> If there are signs of a stroke, call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK) at once. As with any heart condition, call an ambulance for fainting, chest pain or severe shortness of breath: this is the site's general safety rule, repeated at the bottom of every page.

<Quiz />