Aortic root enlargement versus stentless valve implantation for avoidance of patient-prosthesis mismatch in patients with small aortic root: protocol for a systematic review

Abstract

Introduction

Avoiding patient-prosthesis mismatch (PPM) in patients with small aortic annulus (SAA) during aortic valve replacement (AVR) is still a challenging surgical problem. Among surgical options available, aortic root enlargement (ARE) and stentless valve implantation (SVI) are the two most commonly used strategies. This systematic review will be conducted searching for superiority evidence based on comparative studies between these two options.

Methods and analysis

This systematic review will include all relevant articles published from 1 January 1946 to 31 March 2024, with available full texts from Medline (Ovid), Embase, Cochrane Library and Web of Science databases, without any language restriction. Observational studies and randomised controlled trials comparing surgical results of ARE versus SVI for AVR in patients with small aortic root will be screened. Studies will be classified into three groups: group 1 for studies that reported SVI or other tissue valve outcomes without comparing them with ARE outcomes; group 2 for studies that reported ARE outcomes without comparing them with SVI outcomes; and group 3 for studies that compared ARE outcomes with SVI outcomes. The quality of the evidence of each study will be evaluated according to Oxford Centre for Evidence-Based Medicine criteria.

Ethics and dissemination

Ethical approval is not required because no primary data are collected. The findings will be presented at scientific conferences and/or reported in a peer-reviewed scientific journal.

Trial registration number

PROSPERO, CRD42023383793.

Correspondence to Dr Christophe Meneas; [email protected]

Strengths and limitations of this study

• This review will provide a comprehensive assessment regarding superiority evidence for the comparison between aortic root enlargement and stentless valve implantation, the two surgical options used to avoid patient-prosthesis mismatch in patients with a small aortic annulus.

• The reliability of the results will largely depend on the comprehensiveness and the methodological quality of the primary studies included in this review.

• No meta-analysis is planned.

Introduction

Aortic valve replacement (AVR) in patients with a small aortic annulus (SAA) is still a challenging issue.^{1 2} The implantation of the largest possible prosthesis is the first line of action aiming at minimising transvalvular gradient and avoiding the phenomenon of patient-prosthesis mismatch (PPM).^{2 3} Since PPM increases short- and long-term morbidity and mortality,⁴ and despite the discussions about its impact on the outcomes of aortic valve surgery,⁵ PPM should be avoided. The implantation of the ideal prosthesis is not always possible²; there may then be some different options: the implantation of a prosthesis smaller than expected and admitting some degree of PPM, the supra-annular implantation of a stented tissue valve, the enlargement of the root, the implantation of a stentless valve or homograft, the Ross operation or the implantation of a sutureless valve.^{1 6–8} In current times, it seems that two common options accepted by the community are aortic root enlargement (ARE) and stentless valve implantation (SVI). From the available literature, some authors prefer ARE as a reproducible technique with acceptable mortality and morbidity.^{2 6 7} Other authors argue that SVI is the preferred because of its low mortality and morbidity and better hemodynamics.^{1 9 10}

This systematic review will be conducted searching for superiority evidence based on comparative studies between these two options regarding avoidance of PPM. It will be focused on postoperative echocardiographic data especially the indexed effective orifice area (IEOA), mean transvalvular pressure gradient, left ventricular mass index (LVMI), ejection fraction (EF) and left ventricular mass (LV) which are the parameters used to define PPM.⁴

Methods and analysis

Definition of SAA

Currently, there is no clear consensus about the cut-off value to define small aortic root (SAR) or SAA regarding the avoidance of PPM.¹ In surgical series, an SAA is commonly defined as an annulus that would accommodate a prosthesis size ≤ 21 mm.^{1 8 11}

Identification of terms and search strategy

This systematic review will be reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines.¹² It will include all relevant articles published from 1 January 1946 to 31 March 2024, with available full texts from Medline (Ovid), Embase, Cochrane Library and Web of Science databases, without any language restriction. Observational studies and randomised controlled trials comparing surgical results of ARE versus SVI for AVR in patients with SAR will be screened. From the topic of this study, four search terms, “Aortic Root Enlargement”, “Stentless Valve”, “Small Aortic Root” and “Patient-Prosthesis Mismatch”, will be identified, from which keywords will be generated according to free vocabulary and controlled vocabulary using Medical Subject Headings and Emtree terms. These keywords will be combined in search strings using Boolean Operators as demonstrated in table 1. All abstracts generated from the search will be read, and full-text publications of abstracts meeting the search criteria on initial screening will be reviewed to confirm whether the inclusion and exclusion criteria have been met. References from studies meeting these criteria at the full-text stage will be hand-searched to identify further studies for inclusion. The research of all studies will be done by ChM and librarian team of Laval University (Couture Diana Maude (CDM), Beauregard Chantal (BC), Ruel Marianne (RM) and Gagnon Martine (GM)) and discrepancies will be resolved by further discussion.

Table 1

Search strategy

Databases	Number	Search string
Medline (Ovid)	1	(“Root enlarg*” OR “Annul* enlarg*” OR Bentall* OR Konno* OR Manougian OR Manugia OR Nicks OR “Seybold Epting”).ab,ti.
	2	((Stentless adj2 bioprosthes*) OR (Stentless adj2 valv*) OR (Freestyle adj2 bioprosthes*)).ab,ti.
	3	1 OR 2
	4	(“Small aortic root*” OR (Aortic adj2 stenos*)).ab,ti.
	5	“patient prosthesis mismatch*".ab,ti.
	6	exp Aortic Valve Stenosis/
	7	exp Aortic Valve Insufficiency/
	8	6 OR 7
	9	4 OR 5 OR 8
	10	3 AND 9
	11	limit 10 to ed=20190808–20240331
	Final	limit 10 to ed=20190808–20240331
	1	root enlarg*':ab,ti OR 'annul* enlarg*':ab,ti OR bentall*:ab,ti OR konno*:ab,ti OR manougian:ab,ti OR manugia:ab,ti OR nicks:ab,ti OR ’seybold epting:':ab,ti
Embase	2	aortic root enlargement'/exp
	3	#1 OR #2
	4	((stentless NEAR/2 valv*):ab,ti) OR ((stentless NEAR/2 bioprosthes*):ab,ti) OR (freestyle near/2 bioprosthes*):ab,ti
	5	#3 OR #4
	6	small aortic root*':ab,ti OR (aortic NEAR/2 stenos*):ab,ti
	7	small aortic annulus'/exp
	8	aortic valve stenosis'/exp
	9	#7 OR #8
	10	#6 OR #9
	11	patient prosthesis mismatch*'
	12	patient prosthesis mismatch'/exp
	13	#11 OR #12
	14	#10 OR #13
	15	#5 AND #14
	16	#5 AND #14 AND(08-08-2019)/sd NOT(31-03-2024)/sd
	Final	#5 AND #14 AND(08-08-2019)/sd NOT(31-03-2024)/sd
	1	(“Root enlarg*” OR “Annul* enlarg*” OR Bentall* OR Konno* OR Manougian OR Manugia OR Nicks OR “Seybold Epting”):ti,ab,kw”
	2	((Stentless near/2 bioprosthes*) OR (Stentless near/2 valv*) OR (Freestyle near/2 bioprosthes*)):ti,ab,kw”
	3	#1 OR #2
Cochrane Library Web of Science	4	(“Small aortic root*” OR (Aortic near/2 stenos*)):ti,ab,kw”
	5	“Patient prosthesis mismatch*”
	6	MeSH descriptor: (Aortic Valve Stenosis) explode all trees
	7	MeSH descriptor: (Aortic Valve Insufficiency) explode all trees
	8	#6 OR #7
	9	#4 OR #5 OR #8
	10	#3 AND #9
	11	#10 AND (2019/08/08-2024/03/31)
	Final	#10 AND (2019/08/08-2024/03/31)
	1	TS=(“Root enlarg*” OR “Annul* enlarg*” OR Bentall* OR Konno* OR Manougian OR Manugia OR Nicks OR “Seybold Epting”)
	2	TS=((Stentless near/2 bioprosthes*) OR (Stentless near/2 valv*) OR (Freestyle near/2 bioprosthes*))
	3	#1 OR #2
	4	TS=(“Small aortic root*” OR (Aortic near/2 stenos*))
	5	TS=“patient prosthesis mismatch*”
	6	#5 OR #4
	7	#6 AND #3
	8	(LD=2019-08-08/2024-03-31)
	9	#7 AND #8
	Final	#7 AND #8

MeSH, Medical Subject Headings.

Inclusion and exclusion criteria

Studies on patients with SAR undergoing ARE or SVI for AVR or studies reporting a comparison only between groups of patients with SAR undergoing ARE or SVI for AVR will be included. Studies will be included only if some, or all, of the patients underwent ARE or SVI for AVR to avoid PPM with available full-text without any language restriction. All studies dealing with homograft or autograft implantation or reporting transcatheter valve implantation will be excluded. All studies on patients with SAR undergoing sutureless valve implantation will be excluded. Animal studies and cadaver model studies will be excluded, as will non-available full-text articles, letters, reviews, meeting proceedings and case reports.

Data extraction

The following baseline characteristics will be extracted from the included studies: first author, year of publication, country in which the study was performed, study design and period, number of included patients, ARE strategy used, type of prosthesis implanted, postoperative echocardiographic data especially IEOA, LVMI, EF and LV mass, which are the parameters used to define PPM and its haemodynamic consequences.

Evidence quality

The quality of the evidence of each study will be evaluated according to Oxford Centre for Evidence-Based Medicine¹³ criteria. Scores will be assigned to each type of study. Thus, level 1 for properly randomised clinical trial, systematic review with meta-analysis; level 2 for well-designed controlled trial without randomisation; prospective comparative cohort trial; level 3 for case-control studies, retrospective cohort study; level 4 for case series with or without intervention, cross-sectional study; level 5 for opinion of respected authorities and case reports.

Study classification

We will classify the studies into three groups (all eligible studies are focused on ARE or SVI used to avoid PPM in patients with an SAA: Group 1 will include studies that reported the outcomes after SVI or other tissue valve implantation without any comparison with the outcomes after ARE; Group 2 will include studies that reported ARE’s outcomes without comparing them with SVI’s outcomes; and Group 3 will include studies which compared SVI’s outcomes versus ARE’s outcomes.

Patient and public involvement

None.

Ethics and dissemination

Ethical approval is not required because no primary data are collected. The findings will be presented at scientific conferences and/or reported in a peer-reviewed scientific journal.

The authors would like to thank the librarian team of Laval University (Couture Diana Maude (CDM), Beauregard Chantal (BC), Ruel Marianne (RM) and Gagnon Martine (GM)) for their assistance with the design of the search strategy.

Ethics statements

Patient consent for publication

Not applicable.

Footnote

Contributors ChM, conceived the study; PV, CaM reviewed and revised the manuscript. FS, RK, AN, HY-A, SM and FD and all other authors have read the manuscript and approved the final version.

Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

Competing interests None declared.

Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

Provenance and peer review Not commissioned; externally peer reviewed.

References

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² Baikoussis NG, Dedeilias P, Argiriou M. Aortic root enlargement or sutureless valve implantation? Open Access Maced J Med Sci 2016; 4: 742–3. doi:10.3889/oamjms.2016.120

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⁸ Coutinho GF, Correia PM, Paupério G, et al. Aortic root enlargement does not increase the surgical risk and short-term patient outcome? Eur J Cardiothorac Surg 2011; 40: 441–7. doi:10.1016/j.ejcts.2010.11.064

⁹ Beckmann E, Martens A, Alhadi F, et al. Aortic valve replacement with sutureless prosthesis: better than root enlargement to avoid patient-prosthesis mismatch? Interact Cardiovasc Thorac Surg 2016; 22: 744–9. doi:10.1093/icvts/ivw041

¹⁰ Shrestha M, Maeding I, Höffler K, et al. Aortic valve replacement in geriatric patients with small aortic roots: are sutureless valves the future? Interact CardioVasc Thorac Surg 2013; 17: 778–82. doi:10.1093/icvts/ivt291

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¹² Page MJ, McKenzie JE, Bossuyt PM, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. Syst Rev 2021; 10: 89. doi:10.1186/s13643-021-01626-4

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