Atrial Flutter vs Atrial Fibrillation

Atrial flutter and atrial fibrillation are close cousins — both are fast atrial arrhythmias that raise stroke risk — but they look different on the ECG and are cured differently.

The quick answer

Atrial flutter is an organised, regular re-entry circuit that produces sawtooth "flutter" waves, while atrial fibrillation is a disorganised, irregularly irregular rhythm with no P waves. Both start in the atria and both raise stroke risk, but flutter is usually regular and afib is irregular.

Side-by-side comparison

Feature	Atrial flutter	Atrial fibrillation
Atrial activity	Sawtooth flutter waves (~300/min)	Chaotic fibrillatory baseline
Ventricular rhythm	Often regular (e.g. 2:1 → ~150)	Irregularly irregular
Mechanism	Single re-entry circuit (usually right atrium)	Multiple disorganised wavelets
Stroke risk	Elevated	Elevated
Definitive treatment	Cavotricuspid isthmus ablation (very effective)	Pulmonary vein isolation ablation

What they share

Both arrhythmias impair atrial contraction, both can cause palpitations and breathlessness, and both carry a stroke risk that calls for anticoagulation based on the CHA₂DS₂-VASc score. They can even coexist or convert into one another.

How treatment differs

Rate and rhythm control principles are similar, but the ablation targets differ: typical atrial flutter is cured by ablating the cavotricuspid isthmus (a well-defined circuit), which has a very high success rate, whereas atrial fibrillation ablation isolates the pulmonary veins and is more complex.

Key takeaways

• Flutter = sawtooth waves, often regular; AFib = irregularly irregular, no P waves.
• Flutter is a single re-entry circuit; AFib is multiple disorganised wavelets.
• Both raise stroke risk and need anticoagulation assessment.
• Flutter ablation (cavotricuspid isthmus) is simpler and highly effective.

Frequently asked questions

What is the difference between atrial flutter and atrial fibrillation?

Atrial flutter is an organised re-entry rhythm with sawtooth flutter waves and often a regular ventricular rate, while atrial fibrillation is disorganised, irregularly irregular, and has no P waves.

Which is more dangerous, atrial flutter or fibrillation?

Both raise stroke risk and need anticoagulation assessment; neither is inherently benign, though typical flutter is often easier to cure with ablation.

Can atrial flutter turn into atrial fibrillation?

Yes — the two arrhythmias can coexist and convert into one another.

How is atrial flutter treated differently?

Typical atrial flutter is cured by ablating the cavotricuspid isthmus with a high success rate, whereas atrial fibrillation ablation isolates the pulmonary veins and is more complex.

Do both need blood thinners?

Both carry a stroke risk assessed by the CHA₂DS₂-VASc score, and anticoagulation is used when that risk is elevated.