Response of the authors to the letter: Differentiation of wide QRS tachycardia: Garbage in, garbage out

Dear Editor,

Thank you for your comments. I would like to make two clarifications regarding the case report titled “The Exception to Marriott's Sign.” Firstly while you are correct that Marriott's sign is isolated to V1, we wanted to bring to attention an important and common electrical disturbance which can effect the baseline QRS morphology creating a pseudoventricular tachycardia appearance. Namely, as Marriott described in the book challenging ECGs, the presence of concomitant RBBB and LAFB can cause the first R wave to be more positive than the second one in lead V1. Similarly, in the presence of this finding, it is often noted that in V2 as well a more prominent initial R wave is noted initially followed by a lower subsequent R wave. In our case, this was easily noted and while there may have been no other signs suggestive of VT on electrocardiogram, the presence of 1:1 flutter can pose a challenging clinical situation and this finding may help in the diagnosis.

Secondly, the purpose of this case report was not to highlight a rare exception to Marriott's sign, rather it was to point out a rather common finding as you noted yourself in several other examples, which can aid the clinician in making the appropriate diagnosis. Despite Marriott explaining this interesting finding of a concomitant RBBB and LAFB mimicking a VT appearance, I did not easily come across any literature on it available online and felt that discussing this finding in my case would help bring forward a very important principle. This bifasicular block mimicking a VT appearance in QRS morphology in V1 is explained by Marriott (2002). In this case we did not try to prove that there was an exception to Marriott's sign using the findings in V2, rather it was to bring about a principle of bifasicular block creating a pseudo‐VT appearance and this finding can be supported by the presence on an atypical RBBB pattern in V2. Thank you for your comments.