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\begin{document}

\title{''Laser-based therapy: is the right answer for pulmonary vein
isolation?''}



\author[1]{Claudio Tondo}%
\affil[1]{Centro Cardiologico Monzino Istituto di Ricovero e Cura a Carattere Scientifico}%


\vspace{-1em}



  
  \date{June 12, 2024}


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\begin{abstract}
Laser- based PVI has been around for many years and this modality of
ablation is to provide a continuous circular overlapping lesions around
the PVs' ostia. In order to ensure the continuity of the lesion, a
camera is embedded in the system as to guide the placement of sequential
applications with the target to make an adequate overlapping of two
contiguous lesions as to reduce the likelihood of gaps. The first
version of the system required the operator to manually rotate the
catheter as to create a continuous arc of lesion around the PV's ostium.
This approach is time-consuming, with a substantial overall time for
each PV. The evolvement of the technique has been recently offered, with
a novel semi-automated VGLA as to improve ablation efficiency by using a
motorized system which moves the laser arc continuously in order to
reduce the application time and, hopefully, minimize the creation of
gaps.%
\end{abstract}%



\sloppy


\emph{''Laser-based therapy: is the right answer for pulmonary vein
isolation?''}

\textbf{Short title: Laser therapy}

Claudio Tondo, MD, PhD, FESC, FHRS

Department of Electrophysiology\&Cardiac Pacing

Centro Cardiologico Monzino, IRCCS

Department of Biomedical, Surgical and Dentist Sciences, University of
Milan, Milan, Italy.

Correspondence to:

Claudio Tondo, M.D., Ph.D., FESC, FHRS

Director, Department of Electrophysiology\&Cardiac Pacing

Centro Cardiologico Monzino, IRCCS

Department of Biomedical, Surgical and Dentist Sciences

University of Milan, Milan, Italy

Via Carlo Parea, 4 - 20138 Milan, Italy

Mail: claudio.tondo@ccfm.it; claudio.tondo@unimi.it

``Funding None''

``Conflict of Interest: None''

In this issue of the Journal Kuroki et al (1) explores the value of
semi-automated (SA) visually-guided laser ablation (VGLA) for pulmonary
vein isolation (PVI) in comparison with the more conventional manual
(MN) laser ablation. Laser- based PVI has been around for many years and
the main aim of this modality of ablation is to provide a continuous
circular overlapping lesions around the PVs' ostia. In order to ensure
the continuity of the lesion, a camera is embedded in the system as to
guide the placement of sequential applications with the target to make
an adequate overlapping of two contiguous lesions as to reduce the
likelihood of gaps. The first version of the system required the
operator to manually rotate the catheter as to create a continuous arc
of lesion around the PV's ostium.

The amount of energy delivered depends on the anatomic location, being
higher in the anterior portion of the ostium and less in the posterior,
so that the operator can properly titrate the application. This approach
is still time-consuming, since each application takes 20'' to be
completed, thus a substantial overall time for each PV (2) The
evolvement of the technique has been recently offered, with a novel
semi-automated VGLA as to improve ablation efficiency by using a
motorized system which moves the laser arc continuously in order to
reduce the application time and, hopefully, minimize the creation of
gaps.

\textbf{Is the energy source or the technique the ``game changer''?}

Point-by-point RF ablation has been the main ablation modality to
achieve PVI and is still extensively applied in several EP laboratories.
Needless to say that it relies on the operator's skill and can be
time-consuming. The advent of balloon-based platform devices has been
very welcomed, since the manipulation of the catheter is reduced, the
learning curve for operators is pretty simple and fast and most
importantly the clinical outcome is not significantly different from the
conventional RF ablation (3). The use of balloon platforms has then
gained popularity in the EP community, leading to a more extensive use
in several EP Labs with an improved patient workflow. Keeping this in
mind, VGLA belongs to this \emph{family} of ablative approach. As
compared to other balloon-based design catheters, VGLA offers the beauty
to view the atrial tissue and, thus, theoretically to better and
properly deploy the lesions.

One could raise the question whether is the energy source or the ability
to a have a clear vision of the tissue the \emph{turning point} for a
more efficient ablation. In this regard, we diligently need to refer to
the recent data collected in clinical studies comparing VGLA with
point-by-point RF and cryoenergy ablation. A randomized clinical study
comparing the laser balloon with RF in 353 paroxysmal AF patients showed
longer procedure and fluoroscopic times (236\selectlanguage{ngerman}±53 vs 193±64 min,
P\textless{}0.0001, and 36±18 vs 30±21 min, P=0.006) with 98\% acute
efficacy for PVI and an equal 12-months freedom of any atrial
arrhythmias around 61\% (3).

In more detail, laser ablation showed more diaphragmatic paralysis (6 vs
1) but fewer PV stenosis \textgreater{} 50\% (0 vs 5). Furthermore, a
recent European multicenter study (4) comparing the laser balloon with
the cryoballoon showed that the procedure but not fluoroscopy time was
significantly longer (96±20 vs 51±21 min, P\textless{}0.0001, and
8.4±3.2 vs 7.4±4.4 min, P=0.083), while efficacy close to 80\% was the
same for both procedures, and cryoballoon ablation was associated with a
tendency of more transient phrenic nerve palsy (8 vs 2 cases). Based
upon this clinical information, it appears that whatever energy source
is chosen, the outcome is fairly comparable.

\textbf{Making the difference}

Kuroki et al have elegantly investigated if an improved semi-automated
VGLA system could ameliorate the efficiency of this technology compared
to manual manipulation of the catheter. They have clearly demonstrated
in experimental setting that the mean lesion counts were significantly
reduced by using the SA as opposed to MN (5.3±5.9 vs 33.7±10.0, P=0.007)
. This proves an improved efficiency of SA over the MN approach.
Moreover, the lesion counts resulted favorable also in comparison with
RF ablation (28.0±4.4, P=0.019). The catheter use time resulted shorter
for SA as compared to MN in both acute and chronic study (28.0±12.1 to
12.7±15.0 and 28.8±3.8 to 11.5±12.7 min). Of course this represents an
important advantage for the efficiency of the approach and it might
constitute the basis for obtaining a similar outcome even in the
clinical setting. What I would consider quite a fundamental result is
that the SA mode is the homogenous circumferentiality of the lesion and
the transmurality demonstrated both in acute and chronic studies. This
suggests that the uninterrupted movement provided by the SA with
continuous energy application could promote an improved transmurality
over the MN and also with less propensity to create gaps. The gross
anatomy well shows the difference between the two modalities of laser
ablation and support the value of the SA as the preferred mode of deploy
laser energy.

The advantage of directly viewing the tissue is also revealed by the
comparison between laser and RF application, being the level of RF
application deeper in the vein. Therefore, one might conclude that SA
laser modality of ablation ensures a higher level of proximal PV's
ostium lesion continuity, transmurality and less gap formation. The dose
of 13 and 15 W in the current clinically available SA VGLA (5) seems
adequate to promote effective lesions even in humans (6-8). The
improvement of the VGLA system portraying the novel SA modality can be
rightly considered an effective, efficient approach for achieving a high
rate of PVI. We all know there are several new technologies and tools
reaching the EP field, each of them aiming at successful and durable
PVI. We need to applaude Kuroki and co-workers, since their effort was
to show the consistency and the value of VGLA energy applied through a
novel SA technique.

Needless to remind us that other initiatives are taking place in the EP
field, led by researchers and companies as to identify the most
successful ablative approach for PVI. Laser therapy is an attractive
technology belonging to the family of balloon-based platforms and plays
a crucial role in achieving this goal. Reasonably, comparative studies
will be required to establish the relative merit to each proposed
ablative treatment strategy

\textbf{References}

\begin{enumerate}
\tightlist
\item
  Kuroki K, Reddy V, Iwasawa J. et al Pre-clinical evaluation of
  Semi-Automated Lase Ablation for Pulmonary Ven Isolation: A
  Comparative Study, Journal of Cardiov Electrophysiology,\ldots{}.2022
\item
  Dukkipati SR, Cuoco F, Kutinsky et al. Pulmonary Vein Isolation using
  the Visually-Guided Laser Balloon: A Prospective, Multicenter and
  Randomized Comparative to Standard radiofrequency Ablation. Journal of
  the American College of Cardiology 2015;66:1350-60.
\item
  Kuck KH, Brugada J, Furnkranz A, et al. Cryoballoon or radiofrequency
  ablation for paroxysmal atrial fibrillation. N Engl J Med
  2016;376:2235-45
\item
  Chun J, Bordignon S, Mayer L, et al. Cryoballoon versus laserballoon
  insights from the first prospective randomized balloon trial in
  catheter ablation of atrial fibrillation. Circ Arrhythm Electrophysiol
  2021; 14:e0099294
\item
  Neuzil P, Schmidt B, Chun J, et al. Performance of a
  3\textsuperscript{rd} Generation Visually-Guided laser Balloon
  Catheter for Pulmonary Vein Isolation: Results of the X3 Study. Heart
  Rhythm Society's (HRS) 40\textsuperscript{th} Annual Scientific
  Sessions 2019
\item
  Dukkipati SR, Neuzil P, Skoda J et al: Visual balloon-guided
  poin-by-point ablation: reliable reproducible, and persistent
  pulmonary vein isolation. Circulation Arrhythmia and Electrophysiology
  2010;3:266-73
\item
  Koruth JS, Iwasawa J, Enomo Y et al. Chamber-Specific Radiofrequency
  Lesion Dimension Estimation using Novel Catheter-based Tissue
  Interface Temperature Sensing: A preclinical Assessment. JACC Clinical
  Electrophysiology 2017;3:1092-1102
\item
  Gersyenfeld EP, Michele J. Pulmonary vein isolation using a compliant
  endoscopic laser balloon ablation system in a swine model. Journal of
  Interventional Cardiac Electrophysiology: an International Journal of
  Arrhythmias and Pacing 2010;29:1-9
\end{enumerate}

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