The exception to Marriot's sign.

Differentiation of a wide complex arrhythmia can pose as a clinical challenge in the acute care setting. Two broad differentials exist including ventricular tachycardia versus supraventricular tachycardia with aberrancy, underlying bundle branch block or intrinsic conduction defect. To aid in distinguishing between supraventricular tachycardia and ventricular tachycardia, Brugada criteria is commonly used, albeit new algorithms have become more common. Marriott's sign, a taller peak in the first R wave when compared to R' is considered a specific criterion for distinguishing between these two entities and strongly favors the diagnosis of ventricular tachycardia. In this case we present a wide complex tachycardia, which is an exception to Marriott's sign.