Recognising this is perhaps the most important.
Always use caliper or tool in computer.
Always have a same sequence of reviewing EKG.
And, review EKG in its entirety.
Look for Isoelectric line to differentiate AT from A flutter .
Atrial flutter has no isolectric line that is representation of atrial depolarization.
Look for uniformity of morphology.
10-20 % of Atrial Tachycardia can respond to Adenosine. Just a response to Adenosine does not mean it is AV node involved tachycardia.