Atrial Flutter – ECG

Table of Contents

Table of Contents

Published February 2021

Maranda Herner, MD
Expert review – pending


  1. Identify the key ECG findings for atrial flutter (AF) and use three key features to distinguish it from other supraventricular tachycardias (SVTs).

Teaching Instructions

Plan to spend 5-15 minutes familiarizing yourself with the ECG and relevant background information.  Have the image pulled up on the presenting screen or monitor.  Have the image pulled up on the presenting screen or monitor.  Have one learner provide a systematic interpretation of the ECG.  If they do not do so on their own, prompt them to point out the distinguishing characteristics (mostly regular, atrial rate ~300bpm) of this SVT. Then ask them to commit to a specific diagnosis.  Advance through the animations to highlight the abnormalities and final diagnosis.

Official ECG Read: Typical atrial flutter with variable conduction of 3:1 and 4:1 at a ventricular rate of ~75.

Teaching: Atrial flutter is due to a large re-entry circuity, through the cavo-tricuspid isthmus (CTI).  This typically produces an atrial rate ~300bpm with a negative ‘sawtooth’ deflection in lead II.  In the setting of a healthy AV node and no pharmacologic AV nodal blockade this the atrial rate is typically conducted at a 2:1 producing a ventricular rate of ~150bpm.  An abrupt and fixed SVT at a rate of 150bpm should always raise suspicion for atrial flutter and can be effectively identified with vagal maneuvers or imitation of AV nodal blockade. This case demonstrates the result of atrial flutter conducted at variable 3:1 and 4:1 due to the patient taking metoprolol at baseline. Atrial flutter is managed similarly to atrial fibrillation with rate control and anticoagulation.  However, compared to atrial fibrillation, atrial flutter is often more difficult to rate control and is more responsive to cardioversion and EP ablation.

Other resources: Refer to our other post on atrial tachycardia. 


Take Home Point

  1. Atrial flutter is due to a large re-entry circuit in the cavo-tricuscpid isthmus (CTI) often producing sawtooth P waves at a rate ~300bpm with a 2:1 conducted ventricular rate of 150bmp (in the absence of AV nodal disease or blockade).
  2. Compared to atrial fibrillation, atrial flutter is typically more difficult to rate control but more responsive to ablation.


Goldberger, A. L., Shvilkin, A., Goldberger, Z. D. (2017). Clinical Electrocardiography: A Simplified Approach E-Book. United States: Elsevier Health Sciences.

Brandon Fainstad


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