ECG changes in atrial flutter

These include:

• if the P waves are about 300 per minute, and there is a 3:1 block, then the ECG will have a characteristic saw-tooth appearance
• if atrial flutter is associated with a 2:1 block, P waves are difficult to recognise because of the superposition of the preceding T waves
• flutter waves are most clearly seen in V1, II, III & aVF
• an uncertain diagnosis can be confirmed if carotid sinus pressure results in an increase in the uncoupling of the atria and ventricles, revealing the flutter waves
• always consider atrial flutter if a patient has a regular tachycardia of 150

Click here for an ECG example of atrial flutter

Reference

1. Brugada J, Katritsis DG, Arbelo E, et al; ESC Scientific Document Group. 2019 ESC guidelines for the management of patients with supraventricular tachycardia - the Task Force for the management of patients with supraventricular tachycardia of the European Society of Cardiology (ESC). Eur Heart J. 2020 Feb 1;41(5):655-720.