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\begin{document}

\title{Unicuspid aortic valves are no bicuspid aortic valves -- It's time to
retire the Sievers-classification}



\author[1]{Jama Jahanyar}%
\author[2]{Laurent de Kerchove}%
\author[1]{Peter I. Tsai}%
\author[3]{Sameh Said}%
\author[2]{Gebrine Elkhoury}%
\affil[1]{Queen's Medical Center Queen's Heart}%
\affil[2]{Cliniques universitaires Saint-Luc Departement de chirurgie et services associes}%
\affil[3]{Westchester Medical Center}%


\vspace{-1em}



  
  \date{May 26, 2024}


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\begin{abstract}
A general misconception that unicuspid aortic valves (UAV) are just a
subtype of bicuspid aortic valves (BAV) has now been perpetuated in the
medical and surgical community for nearly two
decades{[}1{]}(\#ref-0001), and there is no end in sight.%
\end{abstract}%



\sloppy


\textbf{Unicuspid aortic valves are no bicuspid aortic valves --}

\textbf{It's time to retire the Sievers-classification}

\textbf{Short title:} Bicuspid aortic valve classification

Jama Jahanyar, MD PhD FACS\textsuperscript{1,2}, Laurent de Kerchove, MD
PhD\textsuperscript{1}, Peter I. Tsai, MD FACS\textsuperscript{2}, Sameh
M. Said, MD FACS FACC\textsuperscript{3}, Gebrine El Khoury, MD
PhD\textsuperscript{2}

\textsuperscript{1} Division of Cardiovascular \& Thoracic Surgery,
Queen's Heart Institute, Department of Surgery, John A. Burns School of
Medicine, University of Hawaii, Honolulu, HI, USA

\textsuperscript{\textbf{2}} Department of Cardiovascular \& Thoracic
Surgery, Cliniques Universitaires Saint-Luc, Universit\selectlanguage{ngerman}é Catholique de
Louvain (UCL), Avenue Hippocrate 10, 1200 Brussels, Belgium

\textsuperscript{3}Division of Pediatric Cardiovascular Surgery,
Department of Surgery, Maria Fareri Children's Hospital, Westchester
Medical Center, New York Medical College, Valhalla, NY

\textbf{Conflicts of Interest:} JJ none; LDK none; PIT none; SMS is a
Consultant for Abbot, Stryker, Artivion; GEK none

\textbf{Funding:} none

\textbf{Correspondence:}

Jama Jahanyar, MD PhD FACS

Queen's Heart Institute

1301 Punchbowl St.

Honolulu, HI 96813

Phone~+1 808 -- 691 -1000

jjahanyar@gmail.com

\textbf{Word count:} 1000

A general misconception that unicuspid aortic valves (UAV) are just a
subtype of bicuspid aortic valves (BAV) has now been perpetuated in the
medical and surgical community for nearly two
decades\textsuperscript{1}, and there is no end in sight.

The Sievers classification distinguishes between 3 types of bicuspid
aortic valves. Type 0 is an aortic valve with two symmetric leaflets,
but no raphe (a raphe is a non-functional commissure, as two leaflets
fuse at the commissure to a form a conjoined leaflet). Type I is a
bicuspid aortic valve with a raphe, and the raphe can occur at any
commissure (71\% left/right-, 15\% right/non-, 3\% left/non-commissural
fusion). Type II is described as a bicuspid aortic valve with 2 raphae.
But here also lies the fundamental mistake. We know that unicuspid
aortic valves can present as unicommissural- or acommissural
valves\textsuperscript{2}. Thus, an aortic valve with only one
commissure is simply a unicuspid aortic valve and not a bicuspid aortic
valve. With this, the Sievers classification is now reduced to 2 types
only. The question therefore arises: how helpful is this classification
really?

In a recent study from Denmark, the prevalence of bicuspid aortic valves
in newborns was investigated\textsuperscript{3}. The authors hereby
found an overall prevalence for BAV of 0.77\%. Within this population,
8.7\% of valves had a Type 0 phenotype, 90.8\% were Type I and 0.5\%
Type 2 BAV. In this study, as well as a recent editorial in the Journal
of Cardiac Surgery, the authors have been mistakenly under the
impression that unicuspid aortic valves are just a subtype of
BAV\textsuperscript{3, 4}. Based on the Sievers classification
unfortunately, this is a common notion shared throughout the medical and
scientific community.

Categorization of valve subtypes, however, mainly carries importance in
the surgical arena where different phenotypes require different surgical
approaches for valve repair, with their respective complexities. But in
a surgical setting, to summarize \textgreater{}90\% of BAV phenotypes
with a raphe to just one subtype is utterly useless. Type I BAVs can
range from perfectly symmetric valves to almost tricuspid-like
phenotypes (forme-fruste BAV)\textsuperscript{5}. The Sievers
classification is hence too simplistic and does not provide any roadmap
for potential surgical repair.

Our understanding of BAV phenotypes however, has fundamentally changed
and evolved over the last few years with the landmark study by De
Kerchove et al\textsuperscript{6}. In this study, the investigators
elucidated that commissural orientation, length of cusp fusion of the
conjoined leaflets, and raphe height are intrinsically linked to each
other. A true renaissance in our understanding of BAV morphologies, as
now a wide spectrum of potential BAV phenotypes. This spectrum was
further subcategorized into symmetric-, asymmetric-, and very asymmetric
phenotypes. Symmetric valves thus comprise Sievers Type 0 and I, and the
latter 2 only comprise Type I valves. This improved understanding,
however, has led to a repair-oriented surgical classification for
BAV\textsuperscript{5, 7}, which is based on commissural orientation.
The commissural orientation is easily assessed on echocardiography and
has implication for length of cusp fusion and raphe height. This
provides the surgeon with a clear picture of the valve, in anticipation
of surgical repair. This classification also doesn't mistakenly entail
unicuspid aortic valves as a subtype of bicuspid aortic valves anymore.

The Sievers classification is a relic of the past when our understanding
of BAV morphology was still very limited. With this limited
understanding of valve morphology, a fundamental mistake was introduced
into a widely used BAV classification. Sadly, to this day it is still
confusing the scientific community. The main aim of this editorial, is
to set the record straight. \emph{Unicuspid aortic valves are unicuspid
aortic valves} , and not just a subcategory of bicuspid aortic valves.
Moreover, with a fundamentally improved understanding of bicuspid aortic
valves, more sophisticated classifications are now
available\textsuperscript{5, 7}. These classifications can guide
surgeons in surgical repair of bicuspid aortic valves by providing a
clear picture of valve morphologies, with accordingly, an improved
ability to plan the correct surgical repair strategy ahead of the
operating room.

\textbf{Author contributions:}

\textbf{JJ} -- writing, conceptualization, final approval

\textbf{LDK} -- conceptualization, revision, final approval

\textbf{PIT} -- conceptualization, writing, revision

\textbf{SMS} -- conceptualization, drafting, revision

\textbf{GEK} -- conceptualization, revision, final approval

\textbf{References}

\textbf{1.} Sievers HH, Schmidtke C. A classification system for the
bicuspid aortic valve from 304 surgical specimens. \emph{J Thorac
Cardiovasc Surg.} 2007;133:1226-1233.

\textbf{2.} Jahanyar J, Aphram G, Munoz DE, et al. Congenital unicuspid
aortic valve repair without cusp patch augmentation. \emph{J Card
Surg.}2022;37:2477-2480.

\textbf{3.} Sillesen AS, Vogg O, Pihl C, et al. Prevalence of Bicuspid
Aortic Valve and Associated Aortopathy in Newborns in Copenhagen,
Denmark. \emph{JAMA.} 2021;325:561-567.

\textbf{4.} Jasinski MJ, Kosiorowska K, Berezowski M, Kansy A. Unicuspid
aortic valve repair-Same principles, different methods. \emph{J Card
Surg.} 2022;37:3467-3468.

\textbf{5.} Jahanyar J, El Khoury G, de Kerchove L. Commissural geometry
and cusp fusion insights to guide bicuspid aortic valve
repair.\emph{JTCVS Tech.} 2021;7:83-92.

\textbf{6.} de Kerchove L, Mastrobuoni S, Froede L, et al. Variability
of repairable bicuspid aortic valve phenotypes: towards an anatomical
and repair-oriented classification. \emph{Eur J Cardiothorac Surg.}2019.

\textbf{7.} Jahanyar J, de Kerchove L, El Khoury G. Bicuspid aortic
valve repair: the 180 degrees -Reimplantation technique. \emph{Ann
Cardiothorac Surg.} 2022;11:473-481.

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