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Atrial Flutter

Clinical Subject Page

Atrial Flutter

ICD-10

I09.9

Specialty

Cardiology

Onset

Acute

Reviewed

June 2026

On This Page

Overview

Atrial flutter is a supraventricular tachyarrhythmia (abnormally fast heart rhythm) caused by a macroreentrant electrical circuit within the atria. This rapid atrial activity causes the atria to beat very fast, while the ventricles usually beat at a regular but rapid rate.

Etiology & Risk Factors

  • Atrial flutter has causes similar to those of atrial fibrillation and is caused by a macroreentrant electrical circuit in the atria.

    It may occur in patients with:

    • Structural heart disease
    • Valvular heart disease (especially mitral valve disease)
    • Coronary artery disease
    • Heart failure
    • Cardiomyopathy
    • Pericarditis

    It may also occur after treatment of atrial fibrillation with:

    • Flecainide
    • Propafenone
    • Amiodarone

    Risk Factors

    Cardiovascular

    • Advanced age
    • Hypertension
    • Diabetes mellitus
    • Smoking
    • Obesity
    • Obstructive sleep apnea (OSA)

    Cardiac Disorders

    • Coronary artery disease
    • Valvular heart disease (especially mitral valve disease)
    • Heart failure
    • Cardiomyopathy
    • Pericarditis
    • Wolff-Parkinson-White (WPW) syndrome
    • Sick sinus syndrome

    Noncardiac Conditions

    • COPD, pulmonary embolism, pneumonia
    • Hyperthyroidism
    • Electrolyte abnormalities (hypokalemia, hypomagnesemia)
    • Sepsis or other causes of increased sympathetic activity
    • Cocaine or amphetamine use
    • Excess alcohol (“holiday heart syndrome”)
    • Chronic kidney disease

Pathophysiology

    • Atrial flutter is caused by a macroreentrant electrical circuit within the atria, resulting in rapid, organized atrial depolarization.
    • The atria typically contract at a rate of about 300 beats/minute.
    • The AV node blocks some impulses, so the ventricles usually beat more slowly (commonly with 2:1 or 4:1 AV conduction), producing a regular ventricular rhythm.
    • There are two main types:
      • Typical (Type I) atrial flutter: A reentrant circuit in the right atrium that travels around the tricuspid annulus through the cavotricuspid isthmus.
      • Atypical (Type II) atrial flutter: Reentrant circuits that do not involve the cavotricuspid isthmus, often occurring in the left atrium or other atrial locations.

    Simple Flow

    Macroreentrant circuit in the atria → Rapid atrial rate (~300/min) → AV node blocks some impulses → Regular but rapid ventricular rate → Atrial flutter

Clinical Presentation

  1. Common symptoms

    • Palpitations
    • Dizziness
    • Fatigue
    • Shortness of breath (dyspnea)
    • Syncope (fainting)

    Signs

    • Tachycardia
    • Regular pulse (in most patients)
    • Signs of the underlying heart disease (e.g., murmur of mitral valve disease) may be present.

History Taking

  • “Have you had a sore throat or strep throat in the past few weeks?”
  • “Was it treated with antibiotics?”
  • “Have you had a fever recently?”
  • “Do you have pain or swelling that moves from one joint to another?”
  • “Do you get short of breath during activity or when lying flat?”
  • “Do you have chest pain or palpitations?”
  • “Do you feel unusually tired or weak?”
  • “Have you noticed any skin rash or painless lumps under your skin?”
  • “Have you had any unusual jerky or involuntary movements?”
  • “Have you ever been told you have a heart murmur, rheumatic fever, or a heart valve problem?”
  • “Have you had rheumatic fever or repeated throat infections in the past?”

Atrial Flutter Vs Atrial Fibrillation

Atrial Flutter vs Atrial Fibrillation · Clinical Comparison

Atrial Flutter
Atrial Fibrillation
Mechanism
Organised macro-reentrant circuit — typically in right atrium around the tricuspid annulus (cavotricuspid isthmus-dependent flutter)
Chaotic, disorganised multiple micro-reentrant wavelets throughout both atria — no single organised circuit
Atrial rate
250–350 bpm — typically 300 bpm; regular, organised flutter waves (F waves)
350–600 bpm — chaotic fibrillatory baseline; no true P waves
Ventricular rate
Regular or regularly irregular — fixed AV block ratio (2:1 = 150 bpm; 3:1 = 100 bpm; 4:1 = 75 bpm). Ventricular rate at 150 bpm should always raise suspicion of flutter.
Irregularly irregular — no fixed pattern; rate varies beat to beat (60–180 bpm depending on AV node conduction)
P waves / F waves
Sawtooth flutter (F) waves — negative in II, III, aVF; positive in V1. Regular, continuous, no isoelectric baseline. Best seen when AV block unmasked (carotid sinus massage / adenosine).
Absent P waves — replaced by low-amplitude, irregular fibrillatory (f) waves. Best seen in V1 and II. Wavy, chaotic baseline.
RR intervals
Regular (with fixed block ratio) or regularly irregular (variable block). A hallmark: regular ventricular rhythm at ~150 bpm = flutter until proven otherwise.
Irregularly irregular — the hallmark of AF. No two consecutive RR intervals are the same. Even a single regular RR interval argues against AF.
Typical patient
Structural heart disease, post-cardiac surgery, COPD, pulmonary embolism. Often occurs in patients with underlying AF — the two frequently coexist.
Hypertension, valvular disease (MR/MS), HF, CAD, thyrotoxicosis, sleep apnoea, alcohol excess, diabetes, obesity. Most common sustained arrhythmia.
Vagal manoeuvres / Adenosine
Transiently increases AV block — unmasks sawtooth flutter waves clearly. Does NOT terminate flutter (organised circuit). Very useful diagnostically.
Transiently slows ventricular rate — may briefly clarify the irregular baseline but does not terminate AF or reveal organised waves.
Cardioversion
Highly responsive to electrical cardioversion — often terminates with low energy (50–100J). Also highly responsive to overdrive atrial pacing. Responds well to ibutilide / dofetilide.
Requires higher energy (120–200J biphasic). Pharmacological cardioversion with flecainide, propafenone (pill-in-pocket), or amiodarone. Less responsive than flutter to low-energy shock.
Definitive treatment
Catheter ablation of cavotricuspid isthmus (CTI) — >95% success rate, low recurrence. First-line for recurrent typical flutter. Drug therapy alone has high recurrence.
Pulmonary vein isolation (PVI) — catheter ablation; success ~70–80% for paroxysmal AF. Rate vs rhythm control strategy. AADs: flecainide, propafenone, amiodarone, dronedarone.
Rate control drugs
β-blockers CCBs — often difficult to achieve adequate rate control in flutter; AV node is bombarded at 300 bpm. Ablation preferred over long-term drugs.
β-blockers CCBs (diltiazem/verapamil) Digoxin (for sedentary/HF). Target resting HR <110 bpm (lenient) or <80 bpm (strict).
Anticoagulation
Same as AF — use CHA₂DS₂-VASc score. Flutter carries similar thromboembolic risk to AF, especially if coexisting. DOACs preferred. Anticoagulate ≥3–4 weeks before and after cardioversion if >48h duration.
CHA₂DS₂-VASc score guides OAC. DOACs preferred over warfarin. Lifelong anticoagulation if score ≥2 (male) / ≥3 (female). TOE to exclude LA appendage thrombus before cardioversion if AF >48h.
Prognosis
High recurrence without ablation. ~50% of flutter patients develop AF within 1–2 years. CTI ablation highly curative for typical flutter.
Progressive disease — paroxysmal → persistent → permanent AF over years. Increases stroke risk 5-fold. Associated with HF, dementia, and reduced quality of life.
3 key ECG distinguishing features at a glance
Atrial activity
Flutter
Sawtooth F waves — regular, 300 bpm, negative in II/III/aVF, no isoelectric baseline
AF
Chaotic f waves — irregular, 350–600 bpm, no organised atrial activity
RR regularity
Flutter
Regular or regularly irregular — fixed AV block ratio. Ventricular rate ~150 bpm = flutter until proven otherwise
AF
Irregularly irregular — the hallmark. No two RR intervals the same
Response to adenosine
Flutter
Increases AV block — unmasks sawtooth waves clearly. Diagnostically very useful. Does not terminate flutter.
AF
Transiently slows rate — reveals chaotic fibrillatory baseline. Does not terminate AF or reveal organised waves.
Management summary
Atrial Flutter
Rate control: β-blockers or CCBs — often inadequate; high recurrence on drugs alone
Cardioversion: DC cardioversion (50–100J); overdrive atrial pacing; ibutilide IV
Definitive: CTI catheter ablation — >95% success, curative, recommended for all recurrent typical flutter
Anticoagulation: Same as AF — CHA₂DS₂-VASc score; DOACs preferred
Monitor for AF development — 50% develop AF within 2 years of flutter diagnosis
Atrial Fibrillation
Rate control: β-blockers, diltiazem, verapamil, digoxin. Target HR <110 bpm (lenient)
Rhythm control: Flecainide, propafenone (structurally normal heart); amiodarone, dronedarone
Cardioversion: DC cardioversion 120–200J biphasic; anticoagulate ≥3 weeks before if >48h
Ablation: Pulmonary vein isolation (PVI) — 70–80% success paroxysmal AF
Anticoagulation: CHA₂DS₂-VASc ≥2 (M) / ≥3 (F) → lifelong DOACs

Investigations

    • 12-lead ECG – Gold standard for diagnosis of Atrial Flutter.
      • Classic finding: Sawtooth (F) waves (best seen in leads II, III, and aVF)
      • Narrow QRS complexes
      • Atrial rate around 300 beats/min
      • Ventricular rate usually 75–150 beats/min depending on AV conduction.
    • Cardiac rhythm monitoring
      • Holter monitor or event recorder if episodes are intermittent.
      • Continuous telemetry for hospitalized patients.
    • Transthoracic echocardiography (TTE)
      • Assesses cardiac function and looks for structural heart disease (e.g., valvular disease, atrial enlargement).
    • Transesophageal echocardiography (TEE)
      • Performed before cardioversion in selected patients to exclude left atrial thrombus.
    • Laboratory tests
      • CBC
      • Electrolytes (Na⁺, K⁺, Mg²⁺, Ca²⁺)
      • Thyroid function tests (TFTs)
      • Renal and liver function tests
    • Chest imaging
      • Chest X-ray (CXR) if underlying cardiopulmonary disease is suspected.

    High-Yield Point

Diagnosis

The diagnosis of atrial flutter is confirmed by a 12-lead ECG.

Diagnostic ECG findings:

  • Sawtooth flutter (F) waves (best seen in leads II, III, and aVF) – hallmark finding
  • Atrial rate ≈ 300 beats/min
  • Ventricular rate usually 75–150 beats/min (depends on AV conduction, e.g., 2:1 or 4:1 block)
  • Narrow QRS complexes (if there is no aberrant conduction)
  • Usually a regular rhythm with fixed AV conduction, although variable conduction patterns can occur.

If episodes are intermittent or unclear:

  • Holter monitor or other cardiac rhythm monitoring
  • Electrophysiology (EP) study may be used to distinguish typical from atypical atrial flutter.
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Management of Atrial Flutter

1. Initial Assessment

  • Assess hemodynamic stability (ABCDE approach).
  • Continuous cardiac monitoring and IV access.
  • Identify and treat reversible causes (e.g., electrolyte imbalance, hyperthyroidism).

2. Unstable Patient

  • Immediate synchronized electrical cardioversion (50–100 J biphasic).
  • Start anticoagulation as soon as indicated, but do not delay emergency cardioversion.

3. Stable Patient

  • Rate control
    • Control the ventricular rate with AV nodal blocking therapy (management is similar to atrial fibrillation).
  • Rhythm control
    • Electrical or pharmacologic cardioversion may be considered.
    • Catheter ablation is often the most effective treatment, with better success and lower recurrence than atrial fibrillation.

4. Anticoagulation

  • Assess stroke risk (CHA₂DS₂-VASc) and bleeding risk (HAS-BLED).
  • Anticoagulation recommendations are the same as for atrial fibrillation.

5. Long-Term Care

  • Regular cardiology follow-up.
  • Treat underlying cardiovascular disease and risk factors.
  • Encourage lifestyle modifications (e.g., weight loss, management of obstructive sleep apnea, reduction of alcohol intake).

Complications of Atrial Flutter

  • Progression to atrial fibrillation (most common)
  • 1:1 AV conduction, which can lead to life-threatening ventricular tachycardia

Prognosis of Atrial Flutter

  • Generally good with appropriate treatment.
  • Catheter ablation has better success and lower recurrence than in atrial fibrillation.
  • Many patients respond well to rhythm control, but atrial flutter frequently progresses to atrial fibrillation, so long-term follow-up is important.
  •  

Key Points / Clinical Pearls of Atrial Flutter

  • ECG hallmark of Atrial Flutter: Sawtooth (F) waves
  • Atrial rate: ~300 beats/min
  • Ventricular rhythm: Usually regular
  • Unstable patient: Immediate synchronized electrical cardioversion
  • Stable patient: Rate control or rhythm control
  • Catheter ablation is often the most effective long-term treatment
  • Assess need for anticoagulation using the same recommendations as for atrial fibrillation