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\begin{document}

\title{Reconstruction of the Left Atrium for Atrial Fibrillation Ablation using
the Machine Learning CARTO 3 m-FAM Software}



\author[1]{Arie Schwartz}%
\author[2]{Ehud Chorin }%
\author[2]{Tomer Mann}%
\author[2]{Yuval  Levi}%
\author[1]{Aviram Hochstadt}%
\author[2]{Gilad  Margolis}%
\author[3]{Sami Viskin}%
\author[2]{Shmuel Banai}%
\author[2]{Raphael Rosso}%
\affil[1]{Department of Cardiology, Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel}%
\affil[2]{Tel Aviv Sourasky Medical Center}%
\affil[3]{Tel Aviv Medical Center}%


\vspace{-1em}



  
  \date{May 25, 2024}


\begingroup
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\selectlanguage{english}
\begin{abstract}
IIntroduction: Atrial fibrillation (AF) ablation requires a precise
reconstruction of the left atrium (LA) and pulmonary veins (PV).
Model-based FAM (m-FAM) is a novel module recently developed for the
CARTO system which applies machine-learning techniques to LA
reconstruction. We aimed to evaluate the feasibility and safety of a
m-FAM guided AF ablation as well as the accuracy of LA reconstruction
using the cardiac computed tomography angiography (CTA) of the same
patient LA as gold standard, in 32 patients referred for AF ablation.
Methods: Consecutive patients undergoing AF ablation. The m-FAM
reconstruction was performed with the ablation catheter (Group 1) or a
Pentaray catheter (Group 2). The reconstruction accuracy was confirmed
prior to the ablation by verification of pre-specified landmarks of the
LA and PVs by intracardiac echocardiogram (ICE) visualization and
fluoroscopy. A cardiac CTA performed before the ablation was used as
gold standard of LA anatomy. For each patient, the m-FAM reconstruction
was compared to his/her cardiac CTA. Results: The m-FAM reconstruction
was accurate in all patients regardless the catheter used for mapping.
In 12\% re acquisition of the LA landmarks was necessary to improve the
accuracy. m-FAM time was shorter in group 2 while the M-Fam fluoroscopy
time was similar. Pulmonary vein isolation was achieved in 100\% of
patients without major complications. The m-FAM reconstructions
accurately resemble the cardiac CTA of the same patients. Conclusions:
The m-FAM module allows for rapid and precise reconstruction of the LA
and PV anatomy, which can be safely used to guide AF ablation.%
\end{abstract}%



\sloppy


\textbf{Reconstruction of the Left Atrium for Atrial Fibrillation
Ablation using the Machine Learning CARTO 3 m-FAM Software}

\textbf{Arie Lorin Schwartz*, MD, Ehud Chorin*, PhD, MD, Tomer Mann, MD,
Yuval Levi M.Eng, Aviram Hochstadt, MD, Gilad Margolis, MD, Sami Viskin,
MD,}

\textbf{Shmuel Banai, MD and Raphael Rosso, MD.}

From the Department of Cardiology, Tel Aviv Sourasky Medical Center and
Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.

\textbf{*} Dr. Arie Lorin Schwartz and Dr. Ehud Chorin equally
contributed to the manuscript.

Dr. Rosso serves as consultant for Biosense Webster. This research did
not receive any funding from agencies in the public, private, or
not-for-profit sectors. All authors have reported that they have no
conflicts relevant to the contents of this paper to disclose.

Address reprint requests and correspondence: Dr. Raphael Rosso,
Department of Cardiology, Tel Aviv Sourasky Medical Center, Weizman 6,
Tel Aviv 64239, Israel. E-mail address: roswin1@gmail.com.

\textbf{Abstract:}

\textbf{Introduction:} Atrial fibrillation (AF) ablation requires a
precise reconstruction of the left atrium (LA) and pulmonary veins (PV).
Model-based FAM (m-FAM) is a novel module recently developed for the
CARTO system which applies machine-learning techniques to LA
reconstruction. We aimed to evaluate the feasibility and safety of a
m-FAM guided AF ablation as well as the accuracy of LA reconstruction
using the cardiac computed tomography angiography (CTA) of the same
patient LA as gold standard, in 32 patients referred for AF ablation.

\textbf{Methods:} Consecutive patients undergoing AF ablation. The m-FAM
reconstruction was performed with the ablation catheter (Group 1) or a
Pentaray catheter (Group 2). The reconstruction accuracy was confirmed
prior to the ablation by verification of pre-specified landmarks of the
LA and PVs by intracardiac echocardiogram (ICE) visualization and
fluoroscopy. A cardiac CTA performed before the ablation was used as
gold standard of LA anatomy. For each patient, the m-FAM reconstruction
was compared to his/her cardiac CTA.

\textbf{Results:} The m-FAM reconstruction was accurate in all patients
regardless the catheter used for mapping. In 12\% re acquisition of the
LA landmarks was necessary to improve the accuracy. m-FAM time was
shorter in group 2 while the M-Fam fluoroscopy time was similar.
Pulmonary vein isolation was achieved in 100\% of patients without major
complications. The m-FAM reconstructions accurately resemble the cardiac
CTA of the same patients.

\textbf{Conclusions:} The m-FAM module allows for rapid and precise
reconstruction of the LA and PV anatomy, which can be safely used to
guide AF ablation.

\textbf{Introduction} :

A precise reconstruction of the left atrium (LA), the pulmonary veins
(PV) and the left atrial appendage (LAA) is of critical importance in
order to achieve efficient and safe results during atrial fibrillation
(AF) ablation. The procedure is currently performed with the guidance of
three-dimensional mapping systems. In the CARTO 3 mapping (CARTO System,
Biosense Webster, Inc, Diamond Bar, CA) the LA reconstruction methods
most frequently used are the Fast Anatomical Mapping (FAM) and cardiac
computed tomography angiography (CTA) integration with the
electroanatomic mapping (CARTO Merge).\textsuperscript{1-6}

The existing FAM algorithm currently used in CARTO constructs a
three-dimensional reconstruction of the atrial anatomy by applying a
standard ball-pivoting algorithm to the point cloud acquired by the
catheter. FAM mapping requires catheter manipulation by a skilled
operator and it is frequently time consuming for less experienced
operators. The result does not consider the underlying anatomy, provides
no information in areas where the catheter has not yet visited, and
contains anatomically incorrect artifacts due to deformation of the
atria by the catheter during the mapping procedure, such as merging of
the appendage and left superior pulmonary vein. Therefore, the raw
anatomy obtained with FAM requires post imaging refinement of the LA
surfaces, achieved by shaving the image with ``sculpting tools'' prior
to initiation of the ablation and throughout the procedure. In the CARTO
Merge, the CTA scan of the left atrium is integrated with the FAM
reconstruction. CARTO Merge provides a far better definition of the LA
anatomy, including the areas mentioned above, which are critical for a
successful ablation and provides a clear definition of anatomical
variants, such as PV common ostium, separated branches, or additional
PVs. The drawback of CARTO Merge approach is mainly related to the
exposure of the patients to contrast media and (low dose) radiation
during the cardiac CTA, plus the additional costs of the CTA scan, which
are added to the total cost of the procedure.

Model-based FAM (m-FAM) is a novel module recently developed for the
CARTO 3 system (Biosense Webster). \textsuperscript{7 8} The scope of
the mFAM algorithm is generating an improved, anatomically correct
reconstruction of left atrial anatomy, while at the same time requiring
fewer samples than are currently needed. This is carried out by defining
a parametric model representing a shape of a portion of a heart, and
constructing a statistical prior of the shape from a dataset of other
instances of the portion. The method is further carried out by fitting
the parametric model to the point clouds data and statistical prior to
produce an isosurface of the portion of the heart of the subject, which
is then display in CARTO. m-FAM applies machine-learning techniques to
LA reconstruction using an adaptive model trained from over 300 LA
anatomies obtained from CTA scans. Training was performed to define
statics of relevant proportions and sizes to represent a ``realistic''
and anatomically-accurate left atria. Examples of these features are the
angle between the PVs, distances from atria center to the valve and PV
ostium or the relations of those values to the volume. Having the
geometrical primitives associated with any of the left atria anatomical
structures, as well as keeping the proportions and sizes trained by a
large left atria population, provides a way to represent the most
probable left atria even with very limited information. The algorithm
selects the model that best fits all the available information: points
locations, contact force magnitude and direction, user tagging of
anatomical parts, and a statistical score measuring anatomical
correctness of the model. The reconstruction adapts smoothly to new
points as they are mapped by the catheter, and allows assignment of
special points where the catheter is in contact with the LA surface
(``magnets''), such as ablation points, that constrain the surface while
retaining overall anatomical correctness. The model deforms to best
align with those locations and model reconstruction.

Mathematically, the algorithm can be defined as an optimization problem
in which model parameters that best fit the data and prior statistical
knowledge are estimated in an iterative process. The model is a result
of fitting a parametric shape model to the point cloud acquired by
catheter positions. The model includes a geometrical primitive for each
of the left atria parts, main chamber, pulmonary veins, appendage, and
valve. The geometrical primitives are blended to form the atria
structure. Once the mapping catheter or the ablation catheter introduced
in the LA engage the PVs, their location is tagged on the software and
model fitting begins. A few additional force- and respiration-gated
points are required to further refine the surface and volume of the LA
at key locations, such as the roof, back wall and anterior LA, this
tagged points are called magnet points. After acquisition of enough
magnet points, the software produces a reconstruction of the LA that
includes the LAA ostium and PVs. The model continually self-adjusts with
added ablation tags during the procedure. Importantly, the model is
trained to adjust for non-classical left atrial and pulmonary veins
anatomy as for common ostium or additional side branches. In case of
side branches, these branches are incorporated in the PVs of the closest
major PV. The potential advantages of the m-FAM include: reduction of
the mapping time required to achieve an entire LA reconstruction and
better shaping of the LA anatomy compared to FAM.

In view of the fact that the m-FAM is a totally new feature of the CARTO
3 system, we decided to investigate two different workflows to obtain a
m-FAM reconstruction of the LA using either the ablation catheter (3.5mm
Smart-Touch or 3.5mm ST-SF ablation catheters, Biosense Webster) or a
Pentaray catheter (Biosense Webster) to collect the location tags
required by the software. We opted for a mapping using either the
ablation catheter or a Pentaray catheter because these are the most
commonly catheters used to create the initial LA reconstruction. Of
note, m-FAM reconstruction can also be obtained with a Lasso NAV
catheter (Biosense Webster) if preferred. The accuracy of the m-FAM
reconstruction was confirmed by confirmation of the tagged magnet points
both with fluoroscopy and intra-cardiac echocardiography (ICE) at the
drop-points of the pulmonary veins to precisely define the pulmonary
vein antrum and avoid ablations either too distal or too proximal to the
pulmonary veins as well as the roof, anterior and posterior LA.
Moreover, the m-FAM reconstruction was compared to a cardiac computed
tomography angiography (CTA) of the LA which is routinely performed in
our center prior to ablation of AF. Importantly, for the purpose of this
study, the operator remained blinded to the CTA scan imaging of the
patient during the m-FAM mapping reconstruction and reconstruction
confirmation with ICE and fluoroscopy.

The aim of the present study was to evaluated the feasibility and safety
of the ablation procedure when guided by the m-FAM reconstruction and
the time required to achieve the m-FAM reconstruction and fluoroscopy
time. We also compared the LA reconstruction obtained with m-FAM
obtained with different catheters to the patient's cardiac CTA.

\textbf{Methods:}

\textbf{Study patients:}

Consecutive patients with symptomatic, drug-refractory paroxysmal or
persistent AF referred for ablation were studied. A CTA of the left
atrium was performed before the ablation to assess the left atrial size,
PV anatomy and to exclude the presence of a left atrial appendage
thrombi. The CTA obtained was used as the gold standard to assess the LA
anatomy of the patients enrolled in the study.

\textbf{Atrial fibrillation ablation technique:}

The ablations were performed by three different operators (RR, LAS, UC).
As previously reported\textsuperscript{9}, the procedure was performed
under uninterrupted warfarin therapy (aiming for an INR of 2 on the day
of the procedure) or after skipping a single dose of new oral
anticoagulants (NOAC). The ablation procedure was conducted under
general anesthesia. One decapolar (Livewire decapolar, St. Jude Medical,
Minneapolis, USA) and 1 quadripolar catheter (Biosense Webster, Inc)
were positioned in the coronary sinus and the His bundle position
through the right femoral vein. An intracardiac echocardiogram (ICE)
probe (ACUSON Acunav,~ Siemens Medical Solutions USA, Inc\emph{)} was
positioned in the right atrium through a 9F or 11F sheath introduced in
the left femoral vein. One 8.5F long sheath (SL1, St. Jude Medical,
Minneapolis, USA) was introduced into the left atrium with a single
trans-septal puncture under ICE guidance. Intravenous bolus of heparin
was injected intravenously just prior to the trans-septal puncture and
repeated as needed to maintain an activated clotting time (ACT) of
\textgreater{}350 seconds throughout the procedure. As routine in our
department, the PVs were visualized by selective angiography using a
N.I.H angiography catheter (N.I.H 6F, Cordis, Miami Lakes, FL, USA).

\textbf{m-FAM workflow with ablation catheter (group 1)} :

The ablation catheter was introduced through the original SL1 sheath
into the left atrium. In case of difficulties in manipulation the
ablation catheter in the left atrium, the SL-1 sheath was replaced with
a steerable sheath (Agilis 8.5F, St. Jude Medical, Minneapolis, USA).
The ablation catheter was first introduced deep into the PVs. Then the
catheter was withdrawn and specific landmarks at the pulmonary vein
ostium were tagged (magnet points) on the system for reconstruction.
These magnet points are represented by the drop-point from the left
superior to the left inferior and from the left inferior back to the
left superior (i.e carina), the drop-point from the left inferior to the
left atrium, the drop-point from the left superior to the left atrial
appendage, the anterior and posterior borders of the left inferior
pulmonary vein were tagged. On the septal side, we tagged the anterior
and posterior drop point from the right superior pulmonary vein to the
left atrium, the drop-point from the right superior to the right
inferior pulmonary vein (i.e carina), the drop-point from the from the
right inferior pulmonary vein to the left atrium and the anterior and
posterior borders of the right inferior pulmonary vein at the ostium.
Additional magnet points were tagged at the anterior and posterior left
atrium and at the mid roof. These magnet points are needed to better
define the shape and volume of the left atrial body. At this moment the
m-FAM algorithm was initiated to create a three-dimensional
reconstruction of the left atrium.

Upon acquisition of the m-FAM reconstruction, the accuracy of the m-FAM
reconstruction and location of the specific landmarks at the pulmonary
veins ostium were checked with fluoroscopy and ICE visualization
(Figures 1 and 2).

\textbf{m-FAM workflow with Pentaray/ablation catheter (group 2):}

The Pentaray catheter was introduced through an SL1 sheath or steerable
Agilis sheath into the left atrium. The Pentaray catheter was first
introduced deep in the PVs and then positioned at the PV ostium. The
Pentaray mapping catheter was replaced with the ablation catheter. To
better define the pulmonary vein antrum, the ablation catheter was used
to tag magnet points at the pulmonary vein ostium represented by the
drop point from the left superior to the left inferior and vice versa,
the drop point from the left superior to the left atrial appendage at
the ridge, the drop point from the lower quadrant of the left inferior
to the left atrium and the drop point from the right superior to the
right inferior on the septal side. At this moment the m-FAM algorithm
was initiated to create a three-dimensional reconstruction of the left
atrium. The accuracy of the m-FAM reconstruction and location of the
specific landmarks at the pulmonary vein ostium were checked with
fluoroscopy and ICE visualization (fig. 1 and 2).

In case of lack of accuracy of the initial m-FAM reconstruction, re
acquisition of the magnet points at the pulmonary veins drop-points and
LA body was performed and the software algorithm was reinitiated.

The time required to achieve the M-FAM reconstruction and fluoroscopy
time were also compared between the ablation and Pentaray workflows.

\textbf{Visual inspection of the m-FAM reconstruction and comparison
with the CTA:}

The three-dimensional reconstructions of the LA obtained with the m-FAM
module were shown to the operator prior to the initiation of the
ablation and visually compared to the matching CT scan and to Carto
location points and VisiTag's. Importantly the operator was blinded to
the CT scan of the patient during the LA mapping and m-FAM
reconstruction. The comparison between the m-FAM reconstruction and the
cardiac CTA of the same patient included:

-the LA body morphology

-the presence of common os pulmonary veins

-the PV antrum at the level of WACA

The comparison between the m-FAM and the cardiac CTA was graded as good
or poor.

\textbf{Ablation:}

Ablation was performed using a ``point by point'' technique. Settings
were: catheter irrigation-flow rate of 18 mL/min, target temperature 45\selectlanguage{ngerman}°
and maximal energy of 50 W. During the ablation we aimed to achieve a
contact force of 10 to 20 grams at all times. Radiofrequency energy (RF)
was applied at each ablation site using the automated lesion tagging
ablation-index module (Biosense Webster) to mark the location and
efficacy of each lesion. The ablation-index settings were: catheter
stability position minimum-time of 5 seconds, and maximum range 3-4 mm,
minimum force 3 g, (the blue and yellow marks give two different contact
force values) and lesion tag of 3 mm. The maximal RF time at each
ablation site was 10 seconds for the posterior wall and 25 seconds for
the anterior quadrants. We aimed for an ablation-index value of 400 for
the back wall and 500 for the anterior quadrants. Upon completion of the
wide antral circumferential ablation (WACA), the ablation catheter was
withdrawn from the left atrium and replaced by a lasso circular mapping
catheter (Lasso, Biosense Webster, Inc). The acute end-point of the
procedure was PV isolation demonstrated by disappearance of local PV
electrograms and confirmed by standard pacing maneuvers, to confirm
entrance and exit block, with a lasso circular mapping catheter. In case
of lack of first pass isolation the residual PV-LA connections were
tagged on the CARTO system and additional RF was delivered until PV
isolation was achieved. After a waiting period of 20 minutes, each
pulmonary vein was assessed for entrance and exit block. Each vein was
also assessed for the presence of dormant pulmonary vein-left atrium
connection with intravenous adenosine 18 mg injection. Patients with
evidence of dormant connections revealed by adenosine challenge,
received additional ablations according to the mapping catheter until
the connections were completely abolished.

\textbf{Post-procedure Care:}

After the ablation procedure, patients on warfarin received low
molecular weight heparin until an INR of 2.0--3.0 was achieved. Patients
previously treated with NOACs, underwent the ablation after skipping one
dose. The NOAC therapy was restarted between 3-5 hours post procedure.
Anticoagulation was continued for at least 3 months in patients with
CHA2DS2VASc 0--1 score or indefinitely in patients with CHA2DS2VASc of 2
or more. Antiarrhythmic therapy was restarted immediately after the
procedure and continued for 1 month.

The study protocol was approved by the local ethical committee and
registered in the Israel Ministry of Health (MOH 2020-06-22\_009053).
Written informed consent was obtained from all study subjects. The data
that support the findings of this study are available from the
corresponding author upon reasonable request.

\textbf{Statistical methods:}

Continuous, normally distributed variables are presented as mean ± SD
and compared using the Student's t test. Ordinal and/or non-normally
distributed variables were compared using the Wilcoxon rank-sum test.
Normality was assessed using the Shapiro-Wilk test and visual inspection
of quantile-quantile (QQ) plots and skews. Categorical variables were
compared using the Chi-square test. All analyses were made using ``R''
program language platform (version 3.5.3, 2019-03-11).

\textbf{Results:}

A total of 32 consecutive patients with drug refractory paroxysmal or
persistent atrial fibrillation referred for a first or redo ablation
were enrolled in the present study (Table 1). In 18 patients the m-FAM
reconstruction was conducted with the use of the ablation catheter only
(Group 1), while a Pentaray and ablation catheter were used in 14
patients (Group 2). The CTA of the patients enrolled showed a classical
anatomy with 4 pulmonary veins in 66\% of the patients, while a left
common ostium and a right middle branch was seen in 25\% and 21\%
patients, respectively (table 2).

The m-FAM time was significantly shorter in group 2 while the m-Fam
fluoroscopy time was similar for the two groups. In 4 out of 32 patients
(12\%) enrolled, regardless the mapping catheter used for the
reconstruction re acquisition of the magnet points at the PV ostium and
LA body was required to optimize the reconstruction.

The m-FAM reconstruction accuracy was accurate also in patients with
left common pulmonary veins or right middle branches as in patients with
a classical left atrial anatomy. In case of a right middle branch, the
m-FAM reconstruction displayed the additional branches as part of the
right superior right inferior PV. Regardless to the pulmonary vein
anatomy, the PV antrum at the level of the WACA was accurately
reconstructed.

The visual comparison between the m-FAM and the CT scan was good in all
patients before initiating the ablation. In the four patients in whom
the initial m-FAM reconstruction was inaccurate based on the
confirmation of the PV landmarks with fluoroscopy and ICE, the
comparison with the CT scan was also poor and became good after re
acquisition of the magnet landmarks and re initiation of the m-FAM
software.

All pulmonary vein ablated were successfully isolated. The fluoroscopy
time, dwell time, procedural time and radiofrequency time were similar
for the two groups (Table 2).

No significant complications occurred during or after the procedure.

\textbf{Discussion:}

The m-FAM is a novel algorithm that was recently added to the CARTO 3
system. It allows the easy and fast creation of a 3-dimensional
reconstruction of the LA based on very limited FAM mapping. The system
applies machine learning techniques for LA reconstruction using an
adaptive model trained from over 300 LA anatomies obtained from CTA
scans. However, the accuracy of this reconstruction has not been
verified as well as the feasibility and safety of atrial fibrillation
ablation guided by the m-FAM reconstruction.

In the present study, we also evaluated the m-FAM reconstruction to the
CTA of the LA in the same patient. We found that a precise
reconstruction of the LA can be obtained within 4 minutes (including the
algorithm reconstruction time) and with less than 2 minutes of
fluoroscopy-time regardless to the mapping catheter used. In a minority
of patients, adjustments are needed to improve the accuracy of the
reconstruction. The algorithm performed just as well in patients with LA
anatomy different from the classical four PV anatomy (Figure 5). The
fastest m-FAM reconstruction was obtained with the use of a Pentaray for
mapping. This approach might be preferable in patients in which a
substrate mapping of the left atrium is also required, like patients
with long standing persistent AF. Importantly, the voltage map of the
left atrium can be displayed on the shell of the M-FAM reconstruction
when needed (Figure 5). Despite the shortest mapping time required when
using a Pentaray catheter, the accuracy of the m-FAM map was similar in
patients in whom the maps were created solely with the ablation
catheter. The m-FAM reconstruction closely resembled the LA anatomy
obtained from cardiac CTA in all patients. Pulmonary veins angiography
is routinely performed in our lab during AF ablation and therefore it
was included in the two workflows analyzed in our study. Nevertheless we
believe this step is not mandatory for operators who are not comfortable
with it. The ablation guided with the use of the m-FAM reconstruction
was effective with isolation of 100\% of the pulmonary veins ablated. No
complications occurred in any of the patients treated who underwent an
m-FAM based ablation.

\textbf{Limitations:}

\begin{enumerate}
\tightlist
\item
  Some, but not all variations in PV number and anatomy were represented
  in the study. Accordingly, one should not assume that the accurate
  performance achieved in the few patients with PV variations will be
  reproduced in patients with more uncommon PV anatomy.
\item
  A major limitation of the study is that the gold standard to define
  the accuracy of the LA reconstruction by m-FAM was a visual comparison
  with the CTA of the same patient rather than a computerized ``pattern
  recognition'' formal comparison.
\item
  This is a single center study and our center was involved in the early
  phases of developments of the m-FAM algorithm. Indeed, we performed
  approximately 40 previous cases using the m-FAM as research tool
  before initiating the current clinical study. The large experience
  with the m-FAM algorithm may have influenced our results.
  Nevertheless, our impression is that the learning curve in using the
  m-FAM is very short.
\end{enumerate}

\textbf{Conclusions:}

We describe the first clinical experience of atrial fibrillation
ablation guided by reconstruction of the left atrium obtained with the
novel, machine-learning based software m-FAM for the CARTO system. The
m-FAM allows for an accurate and rapid reconstruction of the left atrium
which can be safely used for guidance during the ablation\textbf{.}

\textbf{References:}

1. Dong J, Dickfeld T, Dalal D, et al. Initial experience in the use of
integrated electroanatomic mapping with three-dimensional MR/CT images
to guide catheter ablation of atrial fibrillation. \emph{J Cardiovasc
Electrophysiol} 2006;17(5):459-66. doi: 10.1111/j.1540-8167.2006.00425.x
{[}published Online First: 2006/05/11{]}

2. Kistler PM, Earley MJ, Harris S, et al. Validation of
three-dimensional cardiac image integration: use of integrated CT image
into electroanatomic mapping system to perform catheter ablation of
atrial fibrillation. \emph{J Cardiovasc Electrophysiol}2006;17(4):341-8.
doi: 10.1111/j.1540-8167.2006.00371.x {[}published Online First:
2006/04/29{]}

3. Kistler PM, Rajappan K, Jahngir M, et al. The impact of CT image
integration into an electroanatomic mapping system on clinical outcomes
of catheter ablation of atrial fibrillation. \emph{J Cardiovasc
Electrophysiol} 2006;17(10):1093-101. doi:
10.1111/j.1540-8167.2006.00594.x {[}published Online First:
2006/09/23{]}

4. Martinek M, Nesser HJ, Aichinger J, et al. Impact of integration of
multislice computed tomography imaging into three-dimensional
electroanatomic mapping on clinical outcomes, safety, and efficacy using
radiofrequency ablation for atrial fibrillation. \emph{Pacing Clin
Electrophysiol} 2007;30(10):1215-23. doi:
10.1111/j.1540-8159.2007.00843.x {[}published Online First:
2007/09/28{]}

5. Mikaelian BJ, Malchano ZJ, Neuzil P, et al. Images in cardiovascular
medicine. Integration of 3-dimensional cardiac computed tomography
images with real-time electroanatomic mapping to guide catheter ablation
of atrial fibrillation. \emph{Circulation} 2005;112(2):e35-6. doi:
10.1161/01.CIR.0000161085.58945.1C {[}published Online First:
2005/07/13{]}

6. Rordorf R, Chieffo E, Savastano S, et al. Anatomical mapping for
atrial fibrillation ablation: a head-to-head comparison of
ultrasound-assisted reconstruction versus fast anatomical
mapping.\emph{Pacing Clin Electrophysiol} 2015;38(2):187-95. doi:
10.1111/pace.12539 {[}published Online First: 2014/12/04{]}

7. Subbarao Choudry MD WWM, Aamir Sofi MD, Meir Bar-Tal MSc,, Jacob S.
Koruth MD MAMM, Stephanie M. Harcum MS, Felicia Biondo BA, Srinivas R.
Dukkipati MD, and Vivek Y. Reddy MD. Rendering of Left Atrial -
Pulmonary Vein Anatomy Using a Model-based Software Algorithm: First Use
in Humans. \emph{Abstract presented at the Heart Rhythm Society Meeting,
Boston (USA) 2019}

8. Subbarao Choudry M, William Whang, MD, FHRS, Aamir A.. Sofi, MD, Jose
Osorio, MD, FHRS, Raphael Rosso, MD, Niels Sandgaard, MD, Alexis
Mechulan, PhD, Michael Wolf, MD, Martin Huemer, MD, Meir Bar-tal, Marc
A. Miller, MD, Jacob S. Koruth, MBBS, MD, Stephanie M.. Harcum, BA,
Srinivas R.. Dukkipati, MD, FHRS and Vivek Y.. Reddy, MD. . Utility Of
An Intelligent Model-based Software Algorithm For Rendering Left Atrial
Anatomy During AF Ablation. \emph{Abstract accepted at the Heart Rhythm
Society Meeting, San Diego (USA) 2020} 2020

9. Rosso R, Chorin E, Levi Y, et al. Radiofrequency Ablation of Atrial
Fibrillation: Nonrandomized Comparison of Circular versus Point-by-Point
''Smart'' Ablation for Achieving Circumferential Pulmonary Vein
Isolation and Curing Arrhythmic Symptoms. \emph{J Cardiovasc
Electrophysiol}2016;27(11):1282-87. doi: 10.1111/jce.13058 {[}published
Online First: 2016/07/30{]}

\textbf{Figure legends:}

Fig.1: m-FAM workflow in group 1 (A) and group 2 (D). Posterior-anterior
and anterior-posterior views of the m-FAM reconstruction compared to the
cardiac CTA of the same patient (B-C in group 1 and E-F in group 2).
Note the minimal FAM required by the system to create a m-FAM
reconstruction

Fig.2: Confirmation of the ablation catheter location with intracardiac
echocardiogram at different landmarks on the m-FAM reconstruction.
Ablation (Abl), left superior pulmonary vein (LSPV), left atrial
appendage (LAA), left interior pulmonary vein (LIPV), right superior
pulmonary vein (RSPV), right inferior pulmonary vein (RIPV)

Fig 3. Example of m-FAM reconstruction. In A and D antero-posterior and
posterior-anterior FAM required for m-FAM reconstruction. B-C
antero-posterior view of the m-FAM reconstruction and cardiac CTA. E-F
posterior-anterior view of the m-FAM reconstruction and cardiac CTA.

Fig.4: In A m-FAM vs cardiac CTA of the LA in a patient with left common
ostium and right middle branch. The substrate analysis mapping is
displayed on the m-FAM reconstruction. In B and C the ablation set of
the WACA in the sane patient displayed on the m-FAM and FAM
reconstruction in posterior anterior view (B) and anterior posterior
view (C)

\textbf{Hosted file}

\verb`Table 1.docx`  available at \url{https://authorea.com/users/357824/articles/562853-reconstruction-of-the-left-atrium-for-atrial-fibrillation-ablation-using-the-machine-learning-carto-3-m-fam-software}

\textbf{Hosted file}

\verb`Table 2.JCE.docx`  available at \url{https://authorea.com/users/357824/articles/562853-reconstruction-of-the-left-atrium-for-atrial-fibrillation-ablation-using-the-machine-learning-carto-3-m-fam-software}

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