\documentclass[10pt]{article}

\usepackage{fullpage}
\usepackage{setspace}
\usepackage{parskip}
\usepackage{titlesec}
\usepackage[section]{placeins}
\usepackage{xcolor}
\usepackage{breakcites}
\usepackage{lineno}
\usepackage{hyphenat}





\PassOptionsToPackage{hyphens}{url}
\usepackage[colorlinks = true,
            linkcolor = blue,
            urlcolor  = blue,
            citecolor = blue,
            anchorcolor = blue]{hyperref}
\usepackage{etoolbox}
\makeatletter
\patchcmd\@combinedblfloats{\box\@outputbox}{\unvbox\@outputbox}{}{%
  \errmessage{\noexpand\@combinedblfloats could not be patched}%
}%
\makeatother


\usepackage{natbib}




\renewenvironment{abstract}
  {{\bfseries\noindent{\abstractname}\par\nobreak}\footnotesize}
  {\bigskip}

\titlespacing{\section}{0pt}{*3}{*1}
\titlespacing{\subsection}{0pt}{*2}{*0.5}
\titlespacing{\subsubsection}{0pt}{*1.5}{0pt}


\usepackage{authblk}


\usepackage{graphicx}
\usepackage[space]{grffile}
\usepackage{latexsym}
\usepackage{textcomp}
\usepackage{longtable}
\usepackage{tabulary}
\usepackage{booktabs,array,multirow}
\usepackage{amsfonts,amsmath,amssymb}
\providecommand\citet{\cite}
\providecommand\citep{\cite}
\providecommand\citealt{\cite}
% You can conditionalize code for latexml or normal latex using this.
\newif\iflatexml\latexmlfalse
\providecommand{\tightlist}{\setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}%

\AtBeginDocument{\DeclareGraphicsExtensions{.pdf,.PDF,.eps,.EPS,.png,.PNG,.tif,.TIF,.jpg,.JPG,.jpeg,.JPEG}}

\usepackage[utf8]{inputenc}
\usepackage[english]{babel}



\usepackage{float}








\begin{document}

\title{Three-dimensional mapping discovered arrhythmic substrate missed in the
initial diagnosis of idiopathic ventricular fibrillation}



\author[1]{Yoshihiro Harano}%
\author[1]{Keita Masuda}%
\author[1]{Shunsuke  Inoue}%
\author[1]{Yuto Iioka}%
\author[1]{Shinya Kowase}%
\author[1]{Jun Osada}%
\author[1]{Kazuhiko Yumoto}%
\affil[1]{Yokohama Rosai Hospital}%


\vspace{-1em}



  
  \date{May 26, 2024}


\begingroup
\let\center\flushleft
\let\endcenter\endflushleft
\maketitle
\endgroup





\selectlanguage{english}
\begin{abstract}
Management of idiopathic ventricular fibrillation (IVF) is challenging
because an arrhythmic substrate may be missed at initial diagnosis;
therefore, careful follow-up and reassessment are necessary.
Three-dimensional mapping would be useful for reassessment of IVF
because it revealed an arrhythmic substrate in a patient, 12 years after
his initial IVF diagnosis. .%
\end{abstract}%



\sloppy


\textbf{Key Clinical Message}

During an initial diagnosis of IVF, an arrhythmic substrate may be
missed for several reasons such as lack of information; thus, a careful
follow-up is important. A three-dimensional mapping may~ identify a
possible missed arrhythmic substrate in IVF .

\textbf{Case report}

Twelve years ago, a 33-year-old man (now 45 years old) with no
significant family history and a medical history of syncope when playing
golf developed sudden cardiac arrest (SCA) after drinking alcohol. His
heartbeat was restored by an automated external defibrillator, and a
fast ventricular tachycardia (VT) with a short cycle length (CL),
including a partially polymorphic waveform, was recorded at another
hospital (Figure 1A). Thus, cardiologists at the previous hospital
judged that this patient had VT or ventricular fibrillation (VF) at that
time. Although various examinations including cardiac magnetic resonance
imaging (MRI), coronary angiography, echocardiogram, and a pilsicainide
provocation test were performed, the underlying heart disease was not
clear. Also, the electrocardiogram (ECG) at rest showed no specific
findings except a complete right bundle branch block (Figure 1B). The
patient was diagnosed with idiopathic ventricular fibrillation (IVF) by
the cardiologists at the previous hospital. An implantable cardioverter
defibrillator (ICD) was not implanted because of his rejection.
Amiodarone was also recommended, but he refused the prescription because
of the possible side effects. Thus, he began oral medication with
bisoprolol 2.5 mg per day for the arrhythmia. However, 5 years later, a
second SCA occurred due to the same ventricular arrhythmia, and he
received an ICD (Dual chamber ICD, mode DDI) implantation after
successful resuscitation.

Twelve years later, the patient was admitted to our hospital for
frequent ICD shocks. His ICD record showed rapid monomorphic VT (mean
CL, 185 ms), which was always triggered by the same premature
ventricular contraction (PVC) (Figure 2A). The morphology of the PVC was
a left bundle branch block configuration with an inferior axis; catheter
ablation of the trigger PVC was performed (Figure 2B). A
three-dimensional (3D) voltage map of the right ventricle was
constructed, and a low-voltage area (LVA) on the free wall of the right
ventricular outflow tract (RVOT) was detected. However, only a few PVCs
were observed during the catheter ablation, and we performed a
pacemap-guided ablation of the PVC. A good pacemap was obtained at the
border zone of the LVA, and the target PVC was ablated at the site.
Shortly after discharge, he experienced a recurrence of ICD shocks and
underwent a second ablation session the following month. However, the
second ablation failed again because very few PVCs were observed, and he
revisited our hospital a month after the second session for frequent ICD
shocks. Monomorphic VT originating from the RVOT was recorded on an ECG
(Figure 3A), and a third ablation session for recurrent VT was
performed. The morphology of the VT was the same as the trigger PVC,
which was frequently observed during his sessions. An almost perfect
pacemap (score, 96) with PVC was obtained near the LVA, slightly
posterior to the prior ablation site. The ventricular potential of the
PVC on the ablation catheter showed up earlier than the QRS onset in any
leads on the ECG at this site (Figure 3B--C). Both VT and PVC were
successfully eliminated and not inducible after ablation. There were no
ICD shocks one-and-a-half years after the last session.

\textbf{Discussion}

In this case, the recorded ventricular tachyarrhythmia on the ICD log at
our hospital was monomorphic VT, not VF. On the other hand, the recorded
log from the other hospital after SCA was fast VT including a partially
polymorphic waveform. Thus, the cardiologists in that hospital judged
that the cause of his SCA was VT or VF and diagnosed him with IVF. This
difference could be explained as follows. VF has been reported to be
sometimes promoted by VT accompanied with hemodynamic instability and
can develop into VF or SCA.\textsuperscript{1} Most VTs originating from
the RVOT are considered as benign arrhythmias; however, some VTs can be
malignant and develop into VF or polymorphic VT; the characteristics of
these malignant VTs are more likely to occur in patients with a history
of syncope and short CL.\textsuperscript{2} This patient had several
events of syncope of unknown cause and monomorphic VT with a very short
CL (185 ms). Therefore, we estimated that his repetitive SCAs were
primarily due to a malignant type of VT originating from the RVOT.~

When a patient with SCA is taken to a hospital, there could be an
initial lack of clinical history and information; therefore, the initial
diagnosis of IVF might be incomplete. In fact, it has been reported that
more than one-fifth of patients initially diagnosed with IVF are
re-diagnosed with another specific disease; hence, continuous follow-up
and reassessment of patients with IVF has become very
important.\textsuperscript{3} This patient presented to our hospital
with IVF and was uneventfully followed-up in the ICD clinic for several
years. When multiple ICD shock events due to monomorphic VT were
detected, we suspected that his diagnosis was possibly not IVF. In the
subsequent ablation session, 3D mapping revealed the existence of an LVA
on the RVOT, which showed that he had a structural arrhythmic substrate.
Moreover, the induced ventricular arrhythmia, which was reproducibly a
monomorphic VT, showed a regular fixed sequence of ventricular
potentials that arose from the LVA. Ablation of the LVA resulted in the
successful elimination of the target PVC and VT. Based on these results,
the patient was finally diagnosed with a scar-related VT, not IVF.

Although cardiac biopsy and genetic examination were not performed, we
ruled out other specific heart diseases before ablation therapy. For
example, his echocardiogram, cardiac MRI, and pilsicainide infusion test
did not show any positive features of Brugada syndrome. Further, the
present case did not match the current diagnostic criteria of
arrhythmogenic right ventricular cardiomyopathy.\textsuperscript{4} For
analyzing other underlying diseases, cardiac biopsy and DNA testing
could have been performed; however, as cardiac biopsy for unexplained
ventricular arrhythmia is not strongly recommended,\textsuperscript{5}
we did not perform it. Moreover, a DNA test was not performed because he
was less likely to have genetic arrhythmia based on his 12-lead ECG at
rest and family history.

Our patient who was initially diagnosed with IVF was eventually
re-diagnosed with a scar-related VT via 3D mapping. In most cases, 3D
mapping has been rarely performed as one of the initial diagnostic tests
for IVF.\textsuperscript{6} Therefore, we suggest that a 3D mapping
system might be useful in finding a missed substrate and in clarifying
another specific arrhythmic disease like in the present case.

\textbf{Conclusion}

We diagnosed a scar-related VT based on 3D mapping results in a patient
who was initially diagnosed with IVF 12 years ago. When managing
patients with IVF, continuous careful follow-up is very important, and
3D mapping could be useful for the reassessment of IVF because an
arrhythmic substrate might have been missed.

\textbf{Author's Contributions}

Keita Masuda elaborated this case report and drafted the manuscript.
Shunsuke Inoue and Yuto Iioka, and Jun Osada attended ablation session
together of the present case and contributed his clinical success.
Shinya Kowase and Kazuhiko Yumoto conceived of this case report and gave
me advice to improve this manuscript. All authors read and approved the
final manuscript.

\textbf{Conflict of Interest}

The authors state that they have no conflict of interest.

\textbf{References}

\begin{enumerate}
\tightlist
\item
  Koplan B.A., Stevenson W.G. 2009. Ventricular tachycardia and sudden
  cardiac death. Mayo Clin Proc 84:289-297.~
\item
  Noda T., Shimizu W., Taguchi A., et al. 2005. Malignant entity of
  idiopathic ventricular fibrillation and polymorphic ventricular
  tachycardia initiated by premature extrasystoles originating from the
  right ventricular outflow tract. J Am Coll Cardiol 46:1288-1294.
\item
  Visser M., van der Heijden J.F., van der Smagt J.J., et al. 2016.
  Long-term outcome of patients initially diagnosed with idiopathic
  ventricular fibrillation: a descriptive study. Circ Arrhythm
  Electrophysiol 9:e004258.~
\item
  Marcus F.I., McKenna W.J., Sherrill D., et al. 2010. Diagnosis of
  arrhythmogenic right ventricular cardiomyopathy/dysplasia: proposed
  modification of the task force criteria. Circulation
  121(13):1533-1541.
\item
  Bennett M.K., Gilotra N.A., Harrington C., et al. 2013. Evaluation of
  the role of endomyocardial biopsy in 851 patients with unexplained
  heart failure from 2000-2009. Circ Heart Fail 6(4):676-684.
\item
  Waldmann V., Bougouin W., Karam N., et al. 2018. Characteristics and
  clinical assessment of unexplained sudden cardiac arrest in the
  real-world setting: focus on idiopathic ventricular fibrillation. Eur
  Heart J 39:1981-1987.~
\end{enumerate}

\textbf{Figure Legends}

\textbf{Figure 1. (A) Electrocardiogram on the patient's first admission
when he was 33 years old.} Fast ventricular tachycardia including a
partially polymorphic waveform and a heart rate of 330 beats per min
were recorded.

\textbf{Figure 1. (B) Electrocardiogram at rest.} Right bundle branch
block was observed.

\textbf{Figure 2. (A) Intracardiac implantable cardioverter
defibrillator record of a monomorphic} \textbf{ventricular tachycardia
(VT).} A monomorphic VT (mean cycle length, 185 ms) was recorded and
consistently triggered by the same premature ventricular contraction
(PVC).

\textbf{Figure 2. (B) Electrocardiogram at rest before the first
ablation therapy.} Complete right bundle branch block and a single PVC
of a left bundle branch block configuration with an inferior axis
observed.

\textbf{Figure 3. (A)} \textbf{Electrocardiogram on admission during a}
\textbf{ventricular tachycardia (VT) storm before the third ablation
therapy.} The morphology of the VT was a left bundle branch block
configuration with an inferior axis. Its estimated origin was the right
ventricular outflow tract. \textbf{}

\textbf{Figure 3. (B) Three-dimensional (3D) voltage map during sinus
rhythm.} Anterior to posterior view of the 3D mapping of the right
ventricle in the third ablation session is superimposed on a
preoperative figure of Computed Tomography. Blue tag indicates a
successful ablation site for premature ventricular contraction and
ventricular tachycardia. White tag indicates a good pacemap with a score
of 96. AP view, anterior-posterior view; PV, pulmonary valve; TV,
tricuspid valve; RV apex, right ventricular apex.

\textbf{Figure 3. (C) Intracardiac electrogram of the success site
during the third ablation therapy.} The distal part of the ablation
catheter (ablation {[}ABL{]} 1U and 1-2) detected depolarization 34 ms
earlier than any other leads of the electrocardiogram. HBE, His bundle
electrogram; RVA, right ventricular apex.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figures/Screen-Shot-2020-08-11-at-8.39.00-AM}

\end{center}
\end{figure}

\selectlanguage{english}
\FloatBarrier
\end{document}

