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\begin{document}

\title{Positive QRS complex in limb lead 2 with negative QRS in lead 3 on
surface electrocardiogram is not indicative of a Right sided accessory
pathway.}



\author[1]{SHARATH KUMAR}%
\author[2]{Garry R. Thomas}%
\affil[1]{Nova Scotia Department of Health and Wellness}%
\affil[2]{Unity Health Toronto}%


\vspace{-1em}



  
  \date{May 16, 2024}


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\begin{abstract}
We read, with interest, the article by Deb et al. entitled
\emph{``Positive QRS complex in limb lead 2 with negative QRS in lead 3
on surface electrocardiogram: A novel predictor for anterior location of
right sided accessory pathways.''} \textsuperscript{1} We would like to
raise a few concerns regarding the interpretation of the
electrocardiographic (ECG) sign they have highlighted.%
\end{abstract}%



\sloppy


\textbf{Title: Positive QRS complex in limb lead 2 with negative QRS in
lead 3 on surface electrocardiogram is not indicative of a Right sided
accessory pathway.}

\textbf{Authors: Sharath Kumar MBBS\textsuperscript{1}, Garry R. Thomas
MD MSc\textsuperscript{2,3}}

\textbf{Affiliations:}

\begin{enumerate}
\tightlist
\item
  Halifax Infirmary, Halifax, Nova Scotia, Canada
\item
  St. Joseph's Health Centre, Unity Health Toronto, Division of
  Cardiology, Department of Medicine, Toronto, Ontario, Canada
\item
  University of Toronto, Toronto, Ontario, Canada
\end{enumerate}

\textbf{Disclosures:} All the authors have no relevant conflict of
interest to disclose.

\textbf{Funding:} None

\textbf{Address for correspondence:}

Garry Robert Thomas

St. Joseph's Health Centre

Unity Health Toronto

30 The Queensway

Toronto, Ontario, Canada

M6R1B5

Telephone: 416-766-1162

Fax: 416-766-0463

Email: garry.thomas@unityhealth.to

Manuscript word count: 420

Key words: Inferior lead discordance, Right sided accessory pathway

We read, with interest, the article by Deb et al.
entitled\emph{``Positive QRS complex in limb lead 2 with negative QRS in
lead 3 on surface electrocardiogram: A novel predictor for anterior
location of right sided accessory pathways.''} \textsuperscript{1} We
would like to raise a few concerns regarding the interpretation of the
electrocardiographic (ECG) sign they have highlighted.

\begin{enumerate}
\tightlist
\item
  The authors propose that inferior lead discordance (ILD) with a
  positive in Lead 2 and negative in Lead 3 is indicative of a right
  anterior accessory pathway (AP); this relies on QRS polarity rather
  than delta wave polarity. This would imply that this sign would have
  the same implication as ventricular arrhythmia arising from the site
  of AP insertion. Based on this assumption, one would conclude that ILD
  would be an indicator of a ``Para-Hisian'' location of the AP rather
  than being removed from it as the authors conclude.\textsuperscript{2}
\item
  Further analysis of the ECGs in Figure 2 shows us that the QRS
  transition is beyond V3 in all ECGs except the third one (ECG
  c).\emph{D'Avila et. al.} \textsuperscript{3} and \emph{Taguchi et.
  al.} \textsuperscript{4} have shown that a positive QRS in V2, or what
  we recognize as an early transition from V1 to V2, is indicative of a
  septal pathway while a late transition is indicative of a right sided
  pathway. So, based on this ECG finding, one would diagnose a right
  sided pathway away from the septum. This simple sign was not
  highlighted in the article.
\item
  \emph{D'Avila et. al} .\textsuperscript{3} have already published that
  a positive QRS in Lead II and a negative in Lead III is indicative of
  a Right sided pathway, suggesting the sign described in this article
  is not novel.. This makes intuitive sense too since right sided
  pathways would be expected to have greater negativity in Lead III. The
  authors of this author did not use the term ``inferior lead
  discordance''
\item
  The authors use this sign as indicative of a right anterior location
  while we believe a right lateral pathway may also have a negative Lead
  III. \emph{Sternick et. al.} \textsuperscript{5} described the ECG
  features of right sided pathways, especially atriofascicular pathways;
  in their publication one can see an atriofascicular pathway with the
  same discordance identified by the authors of this publication. We
  have also observed this discordance in most of the posteroseptal
  accessory pathways we have ablated from the right side. (unpublished)
\end{enumerate}

In conclusion, we disagree with the authors and believe that this
proposed ``discordance'' is an oversimplification, and not reliably
indicative of a right anterior pathway.

\textbf{References:}

\begin{enumerate}
\tightlist
\item
  Bera D, Mukherjee SS, Majumder S, Sikdar S, Dasgupta K, Kar A,
  Kathuria S, Sarkar R. Positive QRS complex in limb lead 2 with
  negative QRS in lead 3 on surface electrocardiogram: A novel predictor
  for anterior location of right-sided accessory pathways (10-1 o'clock
  on tricuspid annulus). J Cardiovasc Electrophysiol. 2022
  May;33(5):953-961. doi: 10.1111/jce.15418. Epub 2022 Feb 28. PMID:
  35175685.
\item
  Enriquez A, Pathak RK, Santangeli P, Liang JJ, Al Rawahi M, Hayashi T,
  Muser D, Frankel DS, Supple G, Schaller R, Lin D, Nazarian S, Zado E,
  Marchlinski FE, Garcia FC. Inferior lead discordance in ventricular
  arrhythmias: A specific marker for certain arrhythmia locations. J
  Cardiovasc Electrophysiol. 2017 Oct;28(10):1179-1186. doi:
  10.1111/jce.13287. Epub 2017 Aug 16. PMID: 28677887.
\item
  d'Avila A, Brugada J, Skeberis V, Andries E, Sosa E, Brugada P. A fast
  and reliable algorithm to localize accessory pathways based on the
  polarity of the QRS complex on the surface ECG during sinus rhythm.
  Pacing Clin Electrophysiol. 1995 Sep;18(9 Pt 1):1615-27. doi:
  10.1111/j.1540-8159.1995.tb06983.x. PMID: 7491305.
\item
  Taguchi N,~Yoshida N,~Inden Y,~Yamamoto T, Miyata S, Fujita M, Yokoi
  K, Kyo S, Shimano M, Hirai M, Murohara T. A simple algorithm for
  localizing accessory pathways in patients with Wolff-Parkinson-White
  syndrome using only the R/S ratio. J Arrhythm,~30~(2013), pp.~439-443
\item
  Sternick EB, Cruz FE, Timmermans C, Sosa EA, Rodriguez LM, Gerken LM,
  Fagundes ML, Scanavacca MI, Wellens HJ. Electrocardiogram during
  tachycardia in patients with anterograde conduction over a Mahaim
  fiber: old criteria revisited. Heart Rhythm. 2004 Oct;1(4):406-13.
  doi: 10.1016/j.hrthm.2004.06.007. PMID: 15851192.
\end{enumerate}

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