Review question The objective of this study is to systematically review the literature of the safety and efficacy outcomes of the transcatheter aortic valve implantation (TAVI) using the self-expanding valve ACURATE neo™ in special populations. Search strategy Databases MEDLINE/Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), Google Scholar and clinicaltrials.gov will be used for all searches. A basic search strategy will be developed for PubMed and modified accordingly for other research engines. We also searched Prospero to check if any similar meta-analysis is in progress in order to avoid duplication with ours. Conference abstracts and references of relevant studies and systematic reviews will be perused, and experts will be contacted in order to identify unpublished studies. Type of study to be included Randomized control trials and cohort studies. Only human studies will be included. In vivo, in vitro and ex vivo trials will be excluded. Participants/population Inclusion Criteria • Adults (over 18 years old) • Patients with severe aortic stenosis • Patients receiving ACURATE NEO device • Studies presenting endpoints according to VARC and VARC-2 criteria Exclusion Criteria • none Interventions, exposures TAVI will be performed in each patient and procedural results will be assessed. Comparators None. Outcomes Primary endpoint: Device success as designated by VARC-2 criteria Secondary endpoints: Mortality, stroke, new pacemaker implantation, major vascular complications, major bleeding, myocardial infarction, acute kidney injury grade II/III, paravalvular regurgitation grade II or III, mean transaortic gradient after TAVI, pre and post dilatation rates. Time frame: 30 days Selection of studies All studies will be imported into a reference management software (EndNote X7). After duplicate removal, two reviewers will independently screen all titles and abstracts and peruse full texts for eligible studies. Any discordance regarding study eligibility will be resolved by consultation with a third review author. Risk of bias (quality) assessment Quality assessment for RCTs will be evaluated according to the revised Cochrane Risk of Bias tool (ROB) 2.0 by two independent reviewers. The quality of the observational studies will be evaluated using a version of the Newcastle Ottawa quality assessment scale for cohort and case-control studies. Data extraction Our systematic review and restrictive meta-analysis will be performed in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). Two reviewers will independently extract data. Any disagreement will be resolved by consensus. Authors will be contacted in order to obtain any missing data relevant to the analysis. Funding sources/sponsors None Conflicts of interest None Language English Country Greece