How can I differentiate between atrial fibrillation and atrial flutter on an ECG?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 21 August 2025Updated: 21 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

A 12-lead electrocardiogram (ECG) is the standard tool used to diagnose atrial fibrillation (AF) . Similarly, an electrocardiographic approach is employed for atrial flutter (AFL), which includes its differential diagnosis . While both conditions are diagnosed via ECG, the provided information does not detail the specific ECG characteristics that differentiate atrial fibrillation from atrial flutter. It is important to note that the CHA2DS2-VASc stroke risk score is used to assess stroke risk in people with either symptomatic or asymptomatic paroxysmal, persistent, or permanent atrial fibrillation, as well as atrial flutter .

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