Key Facts

Atrial flutter is a macro-re-entrant atrial tachycardia characterised by an organised atrial rhythm, typically at a rate of ~300 bpm, with characteristic sawtooth flutter waves on ECG. The ventricular rate depends on the degree of AV conduction (most commonly 2:1, giving ~150 bpm).

Epidemiology

• Less common than AF; incidence ~0.08% per year
• Male:female ratio ~2:1
• Increases with age; peak incidence >80 years
• Often coexists with or precedes AF (~30-50% develop AF)
• Shares similar risk factors with AF

Aetiology

• Similar to AF: hypertension, IHD, heart failure, valvular disease, COPD, post-cardiac surgery
• Often occurs post-AF ablation or with class IC antiarrhythmic drugs (flecainide can convert AF to flutter)

Pathophysiology

• Typical (CTI-dependent) flutter: counter-clockwise macro-re-entrant circuit in the right atrium using the cavotricuspid isthmus as a critical isthmus
• Atypical flutter: non-CTI-dependent circuits; may involve left atrium or right atrial scars (post-surgical)
• Regular atrial activation at ~300 bpm → AV node provides conduction block (2:1, 3:1, 4:1, or variable)
• 1:1 conduction is rare but dangerous (ventricular rate 300 bpm)

Typical Presentation

• Palpitations (regular, rapid)
• Dyspnoea
• Fatigue
• Dizziness or presyncope
• Chest discomfort
• May present with heart failure or stroke (similar to AF)

Signs

• Regular tachycardia (if fixed AV block ratio)
• If variable block: irregularly irregular (can mimic AF)
• Rapid, regular jugular venous 'flutter' waves
• Signs of haemodynamic compromise if 1:1 conduction

Red Flags

• 1:1 conduction (rate ~300 bpm) — haemodynamic collapse
• Pre-excited flutter (WPW) — avoid AV nodal blockers
• Stroke symptoms
• Haemodynamic instability

Bedside

• ECG: sawtooth flutter waves (best seen II, III, aVF, V1); regular ventricular rate ~150 bpm (2:1 block)
• Vagal manoeuvres/adenosine: may transiently increase AV block to reveal flutter waves (diagnostic, not therapeutic)

Bloods

• TFTs: thyrotoxicosis
• U&Es: electrolytes
• FBC: anaemia
• Coagulation: before anticoagulation

Imaging

• Echocardiography: LV function, valvular disease, LA size
• TOE: exclude LA thrombus before cardioversion if not anticoagulated

Special Tests

• Electrophysiology study: if considering ablation; confirms mechanism and isthmus
• CHA₂DS₂-VASc score: stroke risk assessment (same as AF)

Non-pharmacological

• Address underlying precipitants
• Same lifestyle advice as AF (weight, alcohol, exercise)

Pharmacological

Anticoagulation:

• Same as AF: CHA₂DS₂-VASc-based; DOAC preferred
• Treat flutter-related stroke risk identically to AF

Rate control:

• Beta-blocker (bisoprolol 2.5-10mg OD) — first-line
• Rate-limiting CCB (diltiazem 120-360mg MR OD)
• Digoxin (less effective in flutter than AF)
• Rate control often more difficult to achieve in flutter vs AF

Rhythm control:

• DC cardioversion: effective at low energy (50-100J); same anticoagulation rules as AF
• Antiarrhythmic drugs: less effective in flutter than AF; ibutilide or amiodarone may be used
• Avoid flecainide for flutter in isolation (may cause 1:1 conduction — must co-prescribe AV nodal blocker)

Surgical/Interventional

• CTI ablation: definitive treatment for typical flutter
  • Success rate >95%
  • Recurrence rate ~5%
  • Low complication rate
  • Strongly recommended especially in recurrent or drug-refractory cases
  • Does NOT prevent future AF (still need anticoagulation if CHA₂DS₂-VASc indicated)

Referral Criteria

• Consider early referral for CTI ablation (curative for typical flutter)
• Haemodynamic instability: emergency cardioversion
• Atypical flutter: EP study and ablation at specialist centre

• Typical flutter: excellent prognosis with CTI ablation (cure rate >95%)
• Without ablation: tends to be recurrent and difficult to rate-control
• ~30-50% develop AF over time (even after successful flutter ablation)
• Stroke risk similar to AF
• With appropriate anticoagulation and ablation: good long-term outcomes

ECG Features of Atrial Flutter

AV Conduction Ratios