Medically Reviewed By: Dr Paul Lim – MBBS, M.Med (Int Med), MRCP (UK), FAMS (Cardiology)
Heart Rhythm Condition

Atrial Flutter (AFL)

Atrial flutter is a common heart rhythm disorder in which the upper chambers of the heart — the atria — beat in a fast but organised pattern, typically around 240 to 350 times per minute. Unlike the chaotic rhythm of atrial fibrillation, atrial flutter is driven by a single, well-defined electrical circuit. This produces a regular, rapid heartbeat that can cause palpitations, breathlessness and fatigue, and — like atrial fibrillation — raises the risk of stroke. For many patients it can be corrected with a short, targeted procedure.

Dr Paul Lim Chun Yih Senior Consultant Cardiologist & Electrophysiologist
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Dr Paul Lim Chun Yih, Senior Consultant Cardiologist and Electrophysiologist, Singapore
22+ Years of
Clinical Experience
Your Heart Rhythm Specialist

Evaluated by Dr Paul Lim

Senior Consultant Cardiologist & Cardiac Electrophysiologist

Dr Paul Lim subspecialises in heart rhythm disorders, including atrial flutter. He performs catheter ablation, cardioversion, pacemaker and defibrillator implantation, and manages rate-control, rhythm-control and stroke-prevention strategies. He completed advanced fellowship training at Barts Heart Centre, London under Singapore’s HMDP award.

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The Basics

What Is Atrial Flutter?

Atrial flutter is a type of supraventricular arrhythmia — a fast rhythm arising above the ventricles. In a normal heartbeat, each beat begins in the heart’s natural pacemaker (the sinus node) and spreads in an orderly wave. In atrial flutter, the electrical signal instead becomes trapped in a continuous loop (a “re-entry circuit”), most often a large circuit travelling around the right atrium. The atria are driven by this circuit at roughly 240 to 350 beats per minute.

The atrioventricular (AV) node — the electrical gateway between the upper and lower chambers — cannot pass on every one of these rapid signals, so it lets through only a fraction of them. When it passes one beat for every two atrial signals (described as “2:1 conduction”), the resulting pulse is commonly around 150 beats per minute. This 2:1 pattern producing a steady pulse near 150 is one of the classic clues to atrial flutter.

Atrial flutter and atrial fibrillation are closely related and frequently occur in the same person. Atrial flutter can develop into atrial fibrillation over time, and many patients experience both. Identifying which rhythm is present matters, because the treatments — particularly catheter ablation — differ.

Is Atrial Flutter Regular or Irregular?

Atrial flutter is usually a regular rhythm — this is a key difference from atrial fibrillation, which is irregularly irregular. Because the AV node often conducts in a fixed ratio (such as 2:1 or 4:1), the pulse tends to be steady. However, if the conduction ratio varies from beat to beat (“variable block”), the pulse can feel irregular and may be mistaken for atrial fibrillation. A 12-lead ECG is needed to tell the two apart with certainty.

Regular • Sawtooth

What Atrial Flutter Looks Like on an ECG

Rapid, regular atrial activity produces a continuous, repeating “sawtooth” pattern known as flutter (F) waves, with no flat baseline between beats. These are usually clearest in the inferior leads (II, III and aVF) and in lead V1. The ventricular rate is often a neat fraction of the atrial rate — for example a pulse of about 150 from an atrial rate near 300 — and the diagnosis can be confirmed on a simple, painless 12-lead ECG.

What It Feels Like

Symptoms of Atrial Flutter

Some people with atrial flutter have clear symptoms, while others — particularly when the heart rate is well controlled — notice very little.

Common symptoms include:

  • Palpitations — a racing, fluttering, or pounding sensation in the chest
  • Breathlessness, especially during activity
  • Fatigue or a general lack of energy
  • Reduced ability to exercise
  • Dizziness or light-headedness
  • Chest discomfort

When atrial flutter conducts at 2:1 and the pulse sits near 150 beats per minute, symptoms are often more noticeable. Atrial flutter may also be intermittent, coming and going, which can make symptoms unpredictable.

When to seek emergency care

Call 995 or go to the nearest A&E immediately if you experience chest pain, sudden severe shortness of breath, fainting, or signs of a stroke (sudden weakness on one side of the body, trouble speaking, facial drooping, or vision changes). Remember F.A.S.T.: Face drooping, Arm weakness, Speech difficulty, Time to call 995.

Note: atrial flutter symptoms overlap with many other conditions, and the diagnosis can only be confirmed with an ECG — if you are unsure, please book a specialist consultation.

Interactive

How Fast Is Atrial Flutter?

A normal resting heart rate is 60–100 beats per minute (BPM). In atrial flutter the atria fire at around 240–350 BPM, but the pulse you feel depends on how many signals the AV node passes through — 2:1 conduction gives about 150 BPM, 3:1 about 100, and 4:1 about 75. Drag the slider to feel the difference between a normal pulse and a fast, flutter-like rate.

70 bpm
Normal

Normal resting heart rate. Most healthy adults sit in this range at rest — this is what a healthy conduction system produces when everything is working correctly.

Dr Paul Lim

Noticing a fast or fluttering heartbeat? Get a 12-lead ECG and proper specialist evaluation.

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Why It Happens

What Causes Atrial Flutter?

Atrial flutter develops when conditions in the heart allow a re-entry circuit to form — often where the atrial tissue has been stretched, scarred or inflamed. Most patients have one or more underlying contributors.

Heart-related causes

  • High blood pressure
  • Coronary artery disease — narrowing of the heart’s blood vessels
  • Heart valve disease
  • Heart failure — weakening of the heart muscle
  • A previously enlarged or stretched atrium

Causes after heart surgery or ablation

Atrial flutter is particularly associated with scarring of the atria, so it can appear after cardiac procedures:

  • After open-heart or valve surgery, or coronary bypass (CABG)
  • After catheter ablation for atrial fibrillation — new flutter circuits can form around areas of treated tissue
  • After other procedures involving the atria

This type of scar-related flutter is often atypical (see Types, below) and may need specialised mapping to treat.

Lung, thyroid and lifestyle causes

  • Chronic lung disease, or a sudden illness such as pneumonia or a pulmonary embolism
  • An overactive thyroid (hyperthyroidism)
  • Obstructive sleep apnoea
  • Obesity
  • Excessive alcohol, especially binge drinking
  • Intense, prolonged endurance exercise in some individuals

Age is also a factor — atrial flutter becomes more common as people get older. In some patients no single cause is found, but in most a combination of contributors can be identified and treated.

Classification

Typical vs Atypical Atrial Flutter

Atrial flutter is grouped by where its circuit runs, which directly affects how it is treated.

Typical (cavotricuspid isthmus-dependent) atrial flutter

The most common form. The circuit travels around the tricuspid valve in the right atrium, passing through a narrow strip of tissue called the cavotricuspid isthmus (CTI). Because this circuit always crosses the same small area, it can be interrupted very effectively with catheter ablation at that single point. Typical flutter usually produces the classic sawtooth flutter waves on the ECG.

Atypical atrial flutter

Less common and more variable. These circuits run elsewhere — frequently in the left atrium or around areas of scarring from previous surgery or a prior atrial fibrillation ablation. Atypical flutter is often more complex to treat and may require detailed electrical mapping of the heart to locate and interrupt the circuit.

Atrial flutter may also be described as paroxysmal (coming and going on its own) or persistent (continuous until treated).

Know the Difference

Atrial Flutter vs Atrial Fibrillation

Atrial flutter and atrial fibrillation are both supraventricular arrhythmias that arise in the atria and both increase the risk of stroke, but they are not the same condition.

Feature Atrial Flutter Atrial Fibrillation
Electrical pattern One organised re-entry circuit Multiple chaotic electrical wavelets
Atrial rate About 240–350 per minute Often more than 300 per minute
Pulse Usually regular (e.g. steady ~150) Irregularly irregular
ECG appearance Sawtooth flutter (F) waves No P waves; chaotic baseline
Catheter ablation Typical flutter: a single targeted point (CTI) Pulmonary vein isolation; more involved
Stroke risk Raised — anticoagulation often needed Raised — anticoagulation often needed

The two conditions frequently coexist, and one can turn into the other. A common misconception is that atrial flutter is “milder” or “safer” than atrial fibrillation — in terms of stroke risk, the two are treated with the same caution. Telling them apart on an ECG is important because the ablation approach is different and, for typical flutter, often simpler.

Getting a Diagnosis

How Atrial Flutter Is Diagnosed

Atrial flutter is diagnosed with an electrocardiogram (ECG) — a simple, painless test that records the heart’s electrical activity. Because it can come and go, additional monitoring is sometimes needed if a resting ECG is normal.

  1. 1

    Clinical history and examination

    Your cardiologist will ask about your symptoms, triggers, family history and other health conditions, and will check your pulse and blood pressure. A steady, fast pulse around 150 beats per minute can be an early clue to atrial flutter.

  2. 2

    12-lead ECG

    The key test. Atrial flutter has a characteristic sawtooth appearance, and the relationship between the atrial and ventricular rates usually confirms the diagnosis.

  3. 3

    Ambulatory ECG monitoring

    If atrial flutter is suspected but the resting ECG is normal, a wearable monitor can capture intermittent episodes:

    • Holter monitor — a portable ECG worn for 24 hours to several days
    • Event recorder — activated when you feel symptoms, useful for less frequent episodes
    • Implantable loop recorder — a small device placed under the skin to monitor rhythm over a long period, in selected cases
    • Smartwatches and wearables — can flag an abnormal rhythm, but a 12-lead ECG is required to confirm the diagnosis
  4. 4

    Echocardiogram (heart ultrasound)

    A scan of the heart to check chamber size, valve function and pumping strength, all of which guide treatment.

  5. 5

    Blood tests

    Thyroid function, kidney function and a full blood count are usually checked, because thyroid problems and other imbalances can trigger or worsen atrial flutter.

Why It Matters

Why Is Atrial Flutter Serious?

Atrial flutter is rarely immediately life-threatening, but it should not be ignored because of its potential complications.

  • Stroke — when the atria do not contract normally, blood can pool and form clots that may travel to the brain. The stroke risk in atrial flutter is treated as comparable to atrial fibrillation, which is why blood-thinning medication is often recommended.
  • Heart failure — a persistently fast heart rate can weaken the heart muscle over time, a process called tachycardia-induced cardiomyopathy. This often improves once the rhythm or rate is controlled.
  • Reduced quality of life — ongoing palpitations, breathlessness and fatigue can limit daily activities.

The encouraging news is that these risks are largely preventable. Controlling the heart rate or restoring a normal rhythm, together with appropriate stroke-prevention treatment, protects the heart and relieves symptoms.

Modern Care

How Atrial Flutter Is Treated

Treatment has three goals: restoring or controlling the heartbeat, preventing stroke, and treating the underlying causes. Your cardiologist will tailor the plan to your symptoms, the type of flutter, and your overall health.

Restoring normal rhythm — cardioversion

Electrical cardioversion delivers a brief, controlled shock under sedation to reset the heart to a normal rhythm. Atrial flutter usually responds well to cardioversion. Antiarrhythmic medication may also be used to help restore or maintain a normal rhythm.

Controlling the heart rate

When the rhythm is not immediately reset, medication can slow the heart rate to a comfortable level — typically beta-blockers, or rate-slowing calcium-channel blockers such as diltiazem or verapamil, sometimes with digoxin. Atrial flutter can be more difficult to rate-control with medication alone than atrial fibrillation, which is one reason ablation is often considered early.

Catheter ablation

Catheter ablation is a minimally invasive procedure that uses energy delivered through a thin tube (catheter) to interrupt the flutter circuit. For typical atrial flutter, ablation targets the cavotricuspid isthmus — the narrow strip of tissue the circuit must cross. Because the target is small and well defined, catheter ablation of typical atrial flutter has a high success rate with a low chance of the same flutter returning, and it is often recommended as a first-line treatment. Atypical flutter can also be ablated but usually requires more detailed mapping. Dr Paul Lim’s standard is an overnight stay, with most patients going home the next day.

Preventing stroke

Stroke risk is assessed using the CHA2DS2-VA score, which considers factors such as age, high blood pressure, diabetes, heart failure and any previous stroke. Where the risk warrants it, a direct oral anticoagulant (DOAC) — such as apixaban, rivaroxaban, dabigatran or edoxaban — is usually recommended; warfarin is used in selected situations. Importantly, controlling the flutter with ablation does not on its own remove the need for stroke-prevention treatment, which is decided separately based on your overall risk.

Treating the underlying causes

Managing the conditions that drive atrial flutter improves long-term results. This includes treating high blood pressure, an overactive thyroid and sleep apnoea, reducing alcohol, losing excess weight, and reviewing any triggers.

Day-to-Day

Living With and Preventing Atrial Flutter

Most people with atrial flutter lead full, active lives once the condition is well managed.

  • Take any blood-thinning and heart-rate medication exactly as prescribed.
  • Know your triggers. Common ones include alcohol, poor sleep, dehydration and significant stress.
  • Stay active. Moderate-intensity exercise such as brisk walking, swimming or cycling is generally encouraged once your rhythm is controlled; check with your cardiologist about safe limits.
  • Treat the underlying causes. Control blood pressure, address sleep apnoea, manage thyroid problems, and maintain a healthy weight.
  • Attend regular follow-up, particularly after ablation, because some patients go on to develop atrial fibrillation and may need ongoing monitoring.
  • Tell any dentist, surgeon or new doctor that you take anticoagulation before any procedure.
Common Questions

Atrial Flutter FAQ

Answers to the most common questions about atrial flutter, its risks, and how it is treated.

What is atrial flutter?

Atrial flutter is a heart rhythm disorder in which the upper chambers of the heart beat rapidly — usually 240 to 350 times per minute — driven by a single organised electrical circuit. It causes a fast, usually regular heartbeat and can lead to palpitations, breathlessness and fatigue, and it raises the risk of stroke.

What is the difference between atrial flutter and atrial fibrillation?

Both are fast rhythms arising in the atria, but atrial flutter is driven by one organised circuit and is usually regular, while atrial fibrillation is caused by chaotic electrical activity and is irregular. On an ECG, flutter shows a sawtooth pattern, whereas fibrillation shows no clear P waves. Both raise stroke risk similarly. They often occur together, and one can turn into the other.

Is atrial flutter regular or irregular?

Atrial flutter is usually regular, because the AV node conducts the atrial signals in a fixed ratio such as 2:1. If that ratio varies, the pulse can become irregular and may be mistaken for atrial fibrillation. An ECG distinguishes the two.

What does atrial flutter feel like?

Many people feel palpitations — a racing or fluttering chest sensation — along with breathlessness, fatigue, dizziness or reduced exercise tolerance. When flutter conducts at 2:1 and the pulse is around 150, symptoms are often more noticeable. Some people have few or no symptoms.

What causes atrial flutter?

Common contributors include high blood pressure, coronary artery disease, heart valve disease, heart failure, chronic lung disease, an overactive thyroid, obstructive sleep apnoea, obesity and excessive alcohol. It can also develop after heart surgery or after an atrial fibrillation ablation, and it becomes more common with age.

Is atrial flutter dangerous — can you die from it?

Atrial flutter is rarely immediately life-threatening, but untreated it can lead to stroke and, over time, to a weakened heart muscle (heart failure). These risks are largely preventable with appropriate treatment, which is why specialist assessment matters.

Does atrial flutter cause stroke, and do I need a blood thinner?

Atrial flutter raises the risk of stroke, and this risk is treated as comparable to atrial fibrillation. Whether you need a blood thinner is decided using the CHA2DS2-VA score, which weighs factors such as age, blood pressure, diabetes and prior stroke. Many patients with atrial flutter are advised to take anticoagulation.

How is atrial flutter diagnosed?

It is diagnosed with a 12-lead ECG, which shows the characteristic sawtooth flutter waves. If episodes come and go, a Holter monitor, event recorder or implantable loop recorder may be used. An echocardiogram and blood tests complete the assessment.

What is the difference between typical and atypical atrial flutter?

Typical flutter runs around the tricuspid valve in the right atrium, through the cavotricuspid isthmus, and can be treated with a single well-targeted ablation. Atypical flutter runs elsewhere — often in the left atrium or around scar tissue from previous surgery or ablation — and usually requires more detailed mapping to treat.

How is atrial flutter treated?

Treatment may include electrical cardioversion to reset the rhythm, medication to control the heart rate, catheter ablation to interrupt the circuit, and anticoagulation to prevent stroke. The combination is tailored to the individual.

What is the success rate of atrial flutter ablation?

Catheter ablation of typical atrial flutter has a high success rate with a low chance of the same flutter returning, which is why it is often offered as a first-line option. Atypical flutter is also treatable but can be more complex. Some patients later develop atrial fibrillation and need continued follow-up.

Can atrial flutter be cured or go away on its own?

Episodes can sometimes stop on their own, but atrial flutter usually returns unless the underlying circuit and causes are addressed. Catheter ablation of typical flutter can effectively eliminate it in many patients, though ongoing monitoring for atrial fibrillation is still recommended.

Can atrial flutter turn into atrial fibrillation?

Yes. The two conditions are closely linked, frequently coexist, and either can develop into the other. This is one reason follow-up remains important even after successful flutter treatment.

Can I exercise with atrial flutter?

Once your heart rate or rhythm is controlled, moderate-intensity exercise is generally encouraged. Because very intense or prolonged endurance exercise can sometimes trigger arrhythmias, it is best to agree safe limits with your cardiologist.

How much does atrial flutter treatment cost in Singapore?

Costs depend on the treatment and the complexity of your case. Singapore’s Ministry of Health publishes fee benchmarks for procedures such as catheter ablation, and hospital facility, anaesthesia and device charges are billed separately. For an indication of procedure fees, see our catheter ablation page; exact costs are confirmed at consultation.

Concerned About a Fluttering Heartbeat?

Schedule a consultation with Dr Paul Lim for a 12-lead ECG, stroke-risk assessment, and a personalised atrial flutter management plan.

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