Atrial Flutter

Atrial flutter is a regular macro reentrant atrial tachycardia, with atrial rate about 250 to 350 beats per minute.

Typical (cavotricuspid isthmus dependent) flutter: counterclockwise circuit around the tricuspid annulus, producing negative sawtooth flutter waves in II, III, aVF. Clockwise (reverse typical) has positive waves.

Atypical flutter: left atrial or scar related, after cardiac surgery or ablation.

Usually 2:1 AV conduction, giving ventricular rate about 150 beats per minute.

Risk factors: structural heart disease, heart failure, chronic lung disease, thyroid disease, cardiac surgery, alcohol, atrial fibrillation (coexists in many).

Thromboembolic risk similar to AF. Tachycardia induced cardiomyopathy may develop.

• Palpitations, dyspnoea, fatigue, presyncope, chest discomfort; haemodynamic compromise with rapid conduction.
• Regular fast heart rate fixed near 150 beats per minute; neck veins show flutter waves.
• Sudden onset and offset.

• ECG: sawtooth flutter waves at 300 per minute with 2:1 block; vagal manoeuvres or adenosine 6 to 12 mg IV transiently increases block to unmask flutter waves.
• Distinguish from atrial tachycardia, sinus tachycardia, AVNRT.
• Echocardiography for structure and function, atrial thrombus (TOE before cardioversion if over 48 hours).
• Thyroid tests, electrolytes, and CHA2DS2 VASc scoring.
• Electrophysiology study for mapping.

• Unstable: synchronised cardioversion with low energy (50 to 100 J biphasic); usually highly effective.
• Rate control: diltiazem 0.25 mg/kg IV (then 5 to 15 mg/h), verapamil 5 to 10 mg IV, metoprolol 2.5 to 5 mg IV, or esmolol; digoxin or amiodarone in heart failure. Rate control is more difficult than in AF.
• Rhythm control: cardioversion (electrical, or ibutilide 1 mg IV over 10 minutes; atrial overdrive pacing). Observe for 3 weeks of anticoagulation or TOE guidance if duration over 48 hours.
• Anticoagulation per CHA2DS2 VASc as in AF (apixaban 5 mg twice daily, rivaroxaban 20 mg daily).
• Catheter ablation of the cavotricuspid isthmus is first line for typical flutter (success over 95%, recurrence under 10%) and recommended after the first symptomatic episode. Continue anticoagulation based on risk, as AF develops in up to 50% within 5 years.
• Antiarrhythmics (flecainide, propafenone, dofetilide 500 micrograms twice daily, sotalol) are less effective and risk 1:1 conduction; use with AV nodal blockers.
• Atypical flutter: electroanatomical mapping and ablation.
• Treat causes (thyroid disease, alcohol), and cardiac surgery related flutter often resolves.