The differential diagnosis of AVNRT involves all forms of atrioventricular tachycardia, atrial flutter, and the AV reentry tachycardia seen in Wolff-Parkinson-White syndrome.

Atrial Flutter

Type 2 atrial flutter with 1:1 and 2:1 AV conduction is a differential diagnosis for AVNRT. In type 2 atrial flutter, the flutter waves are not appreciated until after vagal maneuvers such as carotid massage. Vagal maneuvers in patients with atrial flutter enhance the AV block and reveal the flutter waves. Conversely, carotid massage on a patient with AVNRT may slow down the tachycardia, but it may also have no effect.

Atrioventricular Reentry Tachycardia in Wolff-Parkinson-White Syndrome

The AVNRT in WPW syndrome resembles a rare type where the P wave appears after the QRS complex, and the RP interval is longer than the PR interval. These findings show that, in patients with WPW syndrome, the impulses in atrioventricular reentry tachycardia take a longer time to travel from the ventricle into the atria. Also, only one pathway of the dual AV conduction is used.

When in sinus rhythm, these patients have a shortened PR interval, a delta wave, and minimally altered QRS and repolarization.

It is often difficult to differentiate the supraventricular tachycardia, specifically among atrial flutter, AV reentry tachycardia in WPW syndrome, AV reentry tachycardia, and AVNRT.