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\begin{document}

\title{Initial Experience of Atrial Septostomy Treatment for Symptomatic
Nonobstructive Hypertrophic Cardiomyopathy: A Case Report}



\author[1]{tao an}%
\author[1]{Yuhui Zhang}%
\author[1]{Jian Zhang}%
\author[1]{Yi Mao}%
\affil[1]{Fuwai Hospital State Key Laboratory of Cardiovascular Disease}%


\vspace{-1em}



  
  \date{May 22, 2024}


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\selectlanguage{english}
\begin{abstract}
Nonobstructive Hypertrophic Cardiomyopathy with preserved EF is a
well-known ejection fraction preserved heart failure and oral medical
therapy is the major treatment. Interatrial shunt devices have
preliminarily been shown to be safe and efficacious for the treatment of
HFpEF, their utilization in nonobstructive hypertrophic cardiomyopathy
patients has not been describe%
\end{abstract}%



\sloppy


Initial Experience of Atrial Septostomy Treatment for Symptomatic
Nonobstructive Hypertrophic Cardiomyopathy: A Case Report

Tao An\textsuperscript{a}; Yuhui Zhang\textsuperscript{a}; Jian
Zhang\textsuperscript{a},Yi Mao\textsuperscript{a*}

\textsuperscript{a}Heart Failure Center, State Key Laboratory of
Cardiovascular Disease, National Center for Cardiovascular Diseases,
Fuwai Hospital, Chinese Academy of Medical Sciencesand Peking Union
Medical College, Beijing, China.

\textsuperscript{*}Correspondence:Yi Mao, Heart Failure Center, State
Key Laboratory of cardiovascular Disease, National Center for
Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical
Sciencesand Peking Union Medical College,China,

Institutional address: No.167 Beilishi Road, Xicheng District, Beijing
100037, China.

Email: 13693305832@139.com

\textbf{Abstract}

\textbf{N} onobstructive Hypertrophic Cardiomyopathy with preserved EF
is a well-known ejection fraction preserved heart failure. Oral medical
therapy is the major treatment for nonobstructive hypertrophic
cardiomyopathy.While interatrial shunt devices have preliminarily been
shown to be safe and efficacious for the treatment of HFpEF, their
utilization in nonobstructive hypertrophic cardiomyopathy patients has
not previously been described.

\textbf{Key words:} heart failure, left-to-right shunt,hypertrophic
cardiomyopathy

INTRODUCTION

No medications has been proven to improve long-term outcomes in patients
with nonobstructive HCM so far\textsuperscript{{[}1{]}}, so the
treatment is focused on relieving symptoms, and improving exercise
capability and quality of life. Dyspnea and chest discomfort are common
symptoms in patients with nonobstructive HCM with preserved EF. These
can be a result of increased LV filling pressures related to diastolic
dysfunction. There has been improvement in outcomes of those with HFpEF
managed with an interatrial shunt device by increasing left-to-right
shunting as a pressure release\textsuperscript{{[}2{]}}. But for HCM,
due to the poor ventricular myocardial relaxation, the cardiac output
greatly depends on the atrial systole for ventricular preloading. So, in
the REDUCE-LAP HF clinical trial, the hypertrophy cardiomyopathy was an
exclusion criterion\textsuperscript{{[}2{]}}. But the hemodynamic of HCM
in different stages is not all the same. If the PCWP was over 25mmHg on
exertion, yet not over 15mmhg at rest, at the same time, the cardiac
output was accessible and blood pressure did not drop sharply in
exercise Swan-Ganz inspection, it is reasonable to make an atrial
septostomy to download the preload of left ventricle.

CASE PRESENTATION

A 52-year-old woman with a history of diagnosis of nonobstructive
hypertrophic cardiomyopathy and atrial~fibrillation for 4 years,
presented with New York Heart Association(NYHA) Class II-III dyspnea,
lower extremity swelling Occasionally; On presentation, blood pressure
was 119/86mmHg,heart rate(HR) 84 beats/min, oxygen saturation
95\%,respiratory rate 15/min; Her symptom was notable for severe
dyspnea on exertion.

Hospital workup included NT-proBNP 2102 pg/ml,a 12-lead
electrocardiogram with atrial fibrillation as well as a chest x-ray that
demonstrated pulmonary edema. An echocardiogram revealed a preserved
ejection fraction 60\%, mild biatrial dilation(54mm for left atrium in
the parasternal long-axis), Moderate tricuspid regurgitation,left
ventricular hypertrophy with middle ventricular septal thickness of 17
mm , Left ventricular outflow tract flow velocity was normal and E/e'
was 11.5.

Prior to further workup, the patient was aggressively dehydrated with
intravenous furosemide. He subsequently underwent right cardiac
catheterization at rest and during supine bicycle exercise which
revealed a resting mean pulmonary artery wedge pressure(PAWP) of 13mmHg,
and exercise peak PCWP of 28 mmHg(EP-PAWP); Mean pulmonary artery
pressures of 20mm Hg, and a mean right atrial pressure of 5mmHg. At
baseline, the 6-min hall walk distance was 325 m; Coronary angiography
was normal; the Kansas city cardiomyopathy questionnaire (KCCQ) quality
of life score was 52. As dyspnea was not alleviated significantly by
diuretics, an interventional course was pursued. Following careful
evaluation by the heart failure team, the patient was considered a
suitable candidate for the atrial septostomy.

With no evidence of severe right-sided heart failure, the patient
underwent atrial septostomy with sequential balloon sizes of 8, and 10mm
(Figure 1 A, B). This was accomplished with high-pressure/non-compliant
Mustang Balloons (Boston scientific). Per
transthoracic~echocardiography, the resulting atrial septal defect
measured 5\textasciitilde{}7.3mm in diameter with evidence of
left-to-right shunting. After this intervention, he underwent exercise
right cardiac catheterization immediately revealed mean PAWP of 14mmHg,
EP-PAWP of 19 mmHg and a mean right atrial pressure of 9mmHg. On the
second day after operation, the 6-min walk distance was 450 m. The
patient noted improvement in dyspnea and was discharged.

At the third month, she continued doing well with NYHA class I symptoms,
requiring half dosage of diuretics, the 6-min walk distance was 417m,
KCCQ score was 26, NT-proBNP was 2416 pg/ml. A follow-up echocardiogram
revealed that a preserved ejection fraction 57\%, mild biatrial dilation
(55mm for left atrium in the parasternal long-axis), Moderate tricuspid
regurgitation,left ventricular hypertrophy with middle ventricular
septal thickness of 17 mm , Left ventricular outflow tract flow velocity
was normal and E/e' was 9, and no obvious left-to-right shunt was
observed.

\textbf{DISCUSSION}

This case report is the first known to employ an atrial septostomy
treatment for nonobstructive hypertrophic cardiomyopathy with preserved
EF. To avoid the unreversible result, only balloon dilation septostomy
was made with gradually increased balloon diameter in case the
unacceptable large interatrial shunt and hemodynamical collapse
appeared.

In the three-month follow-up, the patient's NYHA grades, exercise
capacity, KCCQ improved apparently, and NT-proBNP, left atrium diameter,
LVEF kept in the same level. Theoretically, the septostomy by balloon
angioplasty could only keep the septum defect patent for several
month\textsuperscript{{[}4{]}}. In this case, the defect keep patent at
the third month, and give us a chance to study whether the septostomy
stay efficacious in hemodynamic dimension. it was proved only if the
artificial atrial septum defect be still patent, the symptom of heart
failure is supposed to be relieved significantly.

Atrial septostomy is not a fundamental treatment for HCM pathologically,
so we don't expect it could improve the patients' long term prognosis
greatly, theoretically we even worried about the increased pulmonary
circulation overloading and the right ventricle will lead to heart
function deterioration. But it seemed atrial septostomy be well
tolerated in this HCM case. In fact, RECUCE LAP-HF II presented us with
a neutral result \textsuperscript{{[}2{]}} for heart failure with
preserved and mildly reduced ejection fraction treated with atrial shunt
device. The MACE of atrial septostomy is even significantly improved in
the subgroup with a peak exercise PVR of less than 1.74 Wood units
(n=382, 63.5\% of all patients recruited). That is to say atrial
septostomy is a beneficial treatment to HCM conditionally.

CONCLUSION

Treatment of nonobstructive hypertrophic cardiomyopathy with preserved
EF could be challenging with medical therapy alone, especially for those
diuresis intolerance and resistance patients, and septostomy may provide
significant symptomatic benefit in these patients. The long-term
prognosis is not sure at present, which need more randomized control
trial to provide more evidence.

ACKNOWLEDGMENTS

The authors thank all individuals who participated in this study.
Published with written consent of the patient.

CONFLICT OF INTEREST

The authors report no conflict of interest.

AUTHOR CONTRIBUTIONS

YM ,Y-HZH and J-ZH: studied the conception and designed the study. T-A:
involved in acquisition of data and analysis and interpretation of data
(eg, statistical analysis and computational analysis). T-A, YM, Y-HZH
and J-ZH: wrote, reviewed, and/or revised the manuscript. YM, Y-HZH and
J-ZH: supervised the study.

ETHICAL APPROVAL

The study was approved by the institutional review board.

DATA AVAILABILITY STATEMENT

Data in the current study are available from the corresponding author on
reasonable request.

\textbf{Reference:}

{[}1{]} 2020 AHA/ACC guideline for the diagnosis and treatment of
patients with hypertrophic cardiomyopathy. Michael A. Burke, Sharlene M.
Day, etc, JACC 2020.08.045

\begin{enumerate}
\tightlist
\item
  Atrial shunt device for heart failure with preserved and mildly
  reduced ejection fraction (REDUCE LAP-HF II): a randomized,
  multicenter, blinded, sham-controlled trial Sanjiv J Shah, Barry A
  Borlaug, Eugene S Chung, etc. Lancet 2022.2.25
\item
  Shah SJ, et al. One-year safety and clinical outcomes of a
  transcatheter interatrial shunt device for the treatment of heart
  failure with preserved ejection fraction in the reduce elevated left
  atrial pressure in patients with heart failure (REDUCE LAP-HF I)
  trial: a randomized clinical trial. JAMA Cardiol. 2018;3(10):968--77.
\item
  Chaowu Yan, Guodong Niu,etc. Stable interatrial communication
  combining balloon septostomy and radiofrequency catheter ablation,
  journal of the American College of Cardiology, Volume 72,Issue 15, 9
  October 2018, Pages:1873-75
\end{enumerate}

\textbf{Figure 1}\selectlanguage{english}
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\includegraphics[width=0.70\columnwidth]{figures/image1/image1}

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\end{figure}

FIGURE 1 A and B, balloon dilation of atrial septum

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