EP Q&A; Q14

Event recorder prior to episode of syncope in a 45 y/o man treated with flecainide for AF is shown above.

What is the most likely rhythm diagnosis?

AF with aberrancy.
AF with WPW.
Atrial flutter.
Ventricular Tachycardia.
Artifacts.

Show Answer

Answer: C

The tracing shows borderline wide complex tachycardia with flutter waves seen clearly at the beginning of the tracing (marked with arrows).

The tachycardia later changes to a more rapid one but with identical QRS morphology. The flutter waves remain visible at the same cycle length.

This is an example of 1:1 atrial flutter which is due to the effect of type I antiarrhythmic agent in the absence of effective AV node blockade.

AADs	AV node blocking property	ECG features prompting discontinuation
Flecainide	None	QRS>25% wider
Propafenone	Minimal	QRS>25% wider
Sotalol	A lot	QT>500ms, QT increases>60ms
Amiodarone	moderate	QRS>500ms
Dronedarone	Moderate	QRS>500ms

Ref: 2016 ACC Guidelines for AF and 2016 ESC Guidelines for AF.