How can I differentiate between atrial flutter and atrial fibrillation in a patient presenting with palpitations?

Differentiating atrial flutter from atrial fibrillation in a patient presenting with palpitations primarily relies on electrocardiogram (ECG) findings. Atrial fibrillation is characterised by an irregularly irregular rhythm with no distinct P waves, reflecting chaotic atrial electrical activity, whereas atrial flutter typically shows a regular atrial rhythm with characteristic sawtooth flutter waves, most commonly at a rate of around 250-350 beats per minute, often with a fixed conduction ratio to the ventricles resulting in a regular or regularly irregular ventricular response.

Clinically, both conditions may present with palpitations, but atrial flutter often produces a more regular tachycardia, while atrial fibrillation usually causes an irregularly irregular pulse on manual palpation.

In practice, manual pulse palpation can detect irregularity suggestive of atrial fibrillation, prompting a 12-lead ECG to confirm diagnosis. If atrial flutter is suspected, the ECG will show the typical flutter waves, often best seen in the inferior leads.

Ambulatory ECG monitoring may be required if episodes are paroxysmal and not captured on initial ECG.

Management pathways differ, so accurate differentiation is important; atrial flutter often requires referral to cardiology for consideration of ablation therapy, while atrial fibrillation management includes stroke risk assessment and rate or rhythm control strategies.

Thus, the key to differentiation is ECG interpretation focusing on rhythm regularity and atrial activity patterns.

Summary:

• Atrial fibrillation: irregularly irregular rhythm, absent distinct P waves on ECG.
• Atrial flutter: regular atrial activity with sawtooth flutter waves, often regular ventricular response.
• Manual pulse palpation: irregular pulse suggests atrial fibrillation; regular tachycardia may suggest atrial flutter.
• Confirm diagnosis with 12-lead ECG; consider ambulatory monitoring if paroxysmal.
• Referral and management differ, so accurate diagnosis is essential.

This approach aligns with UK clinical guidelines on palpitations and atrial fibrillation diagnosis and management ¹,², and is supported by cardiology literature describing typical atrial flutter ECG features (Thomas et al., 2016).