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Background
Atrial flutter is a macroreentrant supraventricular tachyarrhythmia characterized by rapid and regular atrial depolarizations, usually at a rate of 240–340 beats per minute. It most commonly results from a single reentrant circuit in the right atrium, producing characteristic sawtooth flutter waves on ECG, particularly in the inferior leads. Unlike the chaotic activity in atrial fibrillation (AF), atrial flutter involves organized atrial activity but still leads to ineffective atrial contractions and increased thromboembolic risk.
II) Classification/Types
By Circuit Type
- Typical Atrial Flutter (Type I):
- Counterclockwise (most common) or clockwise reentry around the tricuspid annulus in the right atrium
- Seen with flutter waves in leads II, III, aVF
- Atypical Atrial Flutter (Type II):
- Involves other regions (left atrium, scar tissue, surgical sites)
- Less predictable ECG morphology
By Conduction Ratio
- 2:1 Atrioventricular (AV) block: Most common, ventricular rate ~150 bpm
- Variable conduction: Irregular ventricular response
- 1:1 conduction: Can lead to dangerously fast ventricular rates (>200 bpm)
Pathophysiology
Atrial flutter typically arises from a macro-reentrant circuit, most often involving the cavotricuspid isthmus in the right atrium. Structural changes (e.g., atrial dilation, fibrosis), scarring from surgery, or atrial inflammation facilitate the circuit. The atrial rate is often too fast for 1:1 AV conduction, resulting in a fixed or variable ventricular response. Loss of coordinated atrial contraction impairs ventricular filling and predisposes to thrombus formation in the atria.
Epidemiology
- Second most common sustained atrial arrhythmia after AF
- More common in older adults and men
- Frequently coexists or alternates with atrial fibrillation
- Often occurs in the setting of structural heart disease or post-cardiac surgery
Etiology
I) Causes
- Ischemic heart disease
- Heart failure
- Hypertensive heart disease
- Valvular disease (especially mitral valve)
- Postoperative states (especially after CABG or valve surgery)
- Congenital heart disease (e.g., atrial septal defect)
- Chronic lung disease (e.g., COPD)
- Hyperthyroidism
- Alcohol use (“holiday heart syndrome”)
II) Risk Factors
- Age >60
- Prior atrial fibrillation
- Left atrial enlargement
- History of catheter ablation
- Obesity, sleep apnea
- Excessive endurance training
Clinical Presentation
I) History (Symptoms)
- Palpitations (sudden onset/offset)
- Fatigue or decreased exercise tolerance
- Dyspnea
- Lightheadedness or presyncope
- Chest discomfort
- Occasionally asymptomatic
- Thromboembolic events (e.g., stroke)
II) Physical Exam (Signs)
- Regular or irregular tachycardia (depending on AV conduction)
- Fluttering sensation in chest or neck
- Fixed rapid heart rate (~150 bpm in 2:1 block)
- Signs of heart failure if decompensated
- Embolic signs (e.g., aphasia, hemiparesis, cold limb)
Differential Diagnosis (DDx)
- Atrial fibrillation
- SVT (e.g., AVNRT)
- Sinus tachycardia
- Multifocal atrial tachycardia
- Ventricular tachycardia
- Hyperthyroidism or pheochromocytoma
- Anxiety or panic disorder
Diagnostic Tests
Initial Work-Up
- ECG: Sawtooth flutter waves best seen in leads II, III, aVF; atrial rate ~300 bpm with regular ventricular response if 2:1 block
- Telemetry or Holter monitor: Detect intermittent or paroxysmal flutter
- Echocardiography: Assess LA size, LV function, valvular lesions, thrombus
- TSH, Free T4: Rule out thyrotoxicosis
- Electrolytes, renal function, BNP: Identify reversible factors
- Transesophageal echocardiography (TEE): Before cardioversion to exclude atrial thrombus if AF duration >48 hours or unknown
- CHADS₂-VASc score: Estimate stroke risk
Treatment
I) Initial Approach
- Unstable (hypotension, chest pain, pulmonary edema):
- Immediate synchronized electrical cardioversion
- Stable:
- Rate control, rhythm control, and stroke prevention
II) Medications
Drug Class | Examples | Notes |
Rate control | Metoprolol, Diltiazem, Digoxin | Control ventricular rate, especially in 2:1 AV block |
Rhythm control | Amiodarone, Ibutilide | Preferred for acute conversion; consider in symptomatic patients |
Anticoagulation | Apixaban, Rivaroxaban, Warfarin | Based on CHA₂DS₂-VASc score |
Antiarrhythmics | Flecainide, Dofetilide | Used in maintenance or cardioversion |
Electrolyte correction | Potassium, Magnesium | Prevent recurrent arrhythmias |
Ablation | Catheter ablation of cavotricuspid isthmus | Definitive treatment with high success (~90%) |
Consults/Referrals
- Cardiology: Initial management and follow-up
- Electrophysiologist: For ablation or recurrent flutter
- Neurology: If stroke or TIA occurs
- Anticoagulation services: For INR monitoring if on warfarin
Patient Education, Screening, Vaccines
Education
- Recognize symptoms (palpitations, dyspnea)
- Importance of medication adherence
- Monitor for signs of bleeding if anticoagulated
- Avoid alcohol, stimulants
- Risk of stroke and need for anticoagulation
Screening/Prevention
- Opportunistic ECG screening in elderly or those with heart failure
- Postoperative arrhythmia monitoring
- Consider long-term Holter in recurrent palpitations
Vaccinations
- Influenza and pneumococcal vaccines
- COVID-19 vaccination as per current guidelines
Follow-Up
Short-Term
- Reassess rate/rhythm control
- Monitor ECG rhythm
- Ensure anticoagulation coverage
- Monitor for recurrence or transition to AF
Long-Term
- Re-evaluate CHA₂DS₂-VASc score
- Periodic echocardiography if structural disease
- Consider catheter ablation if recurrent/flutter persists
- Monitor for conversion to or coexistence with AF
Prognosis
- Excellent with ablation (typical flutter cure rate ~90%)
- Lower thromboembolic risk than AF, but still significant
- Untreated: risk of tachycardia-induced cardiomyopathy, stroke
- High rate of recurrence or progression to AF
