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Methods: A systematic review followed PRISMA 2020, searching PubMed, EMBASE, MEDLINE, and ClinicalTrials.gov for studies assessing microcirculatory indices or involving CMD patients undergoing CSR. Results: Seventeen studies were included; CSR was linked with improved microvascular function, lower microvascular resistance, increased coronary flow reserve, and consistent angina severity, exercise capacity, and quality-of-life improvements. Conclusions: Potential clinical and physiological benefit is suggested, but small non-randomized cohorts and uncertainty about long-term outcomes require well-powered randomized trials.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/coronary-sinus-reduction-for-refractory-angina-caused-by-microvascular-dysfunction-a-systematic-review/461556/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/coronary-sinus-reduction-for-refractory-angina-caused-by-microvascular-dysfunction-a-systematic-review/461556.png","ImageObject",300,407,{"name":92,"@type":93},"kopisore","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-07","2026-09-30",true,{"@type":102,"interactionType":103,"userInteractionCount":29},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What question does the systematic review address about coronary sinus reducer (CSR) in CMD-related refractory angina?","Question",{"text":112,"@type":113},"It assesses the impact of CSR implantation on coronary biological and physiological function and summarizes evidence across completed and ongoing trials in patients with refractory angina caused by CMD.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How were studies selected in this review?",{"text":117,"@type":113},"The review followed PRISMA 2020 and searched PubMed, EMBASE, MEDLINE, and ClinicalTrials.gov for studies assessing microcirculatory indices or primarily including CMD patients undergoing CSR.",{"name":119,"@type":110,"acceptedAnswer":120},"What outcomes were reported after CSR implantation across included studies?",{"text":121,"@type":113},"Observational studies and case series reported significant improvements in microvascular function, including reductions in microvascular resistance and increases in coronary flow reserve, along with consistent improvements in angina severity (CCS class), exercise capacity, and quality-of-life measures.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},461556,1790792895,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":29,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":139,"language":140,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":67,"update_tm":144,"read_time":36},962090880963,"https://ap-avatar.wpscdn.com/davatar_6f874abed73319feea01a86fa6f0fab8","Systematic Review  \nCoronary Sinus Reduction for Refractory Angina Caused by Microvascular Dysfunction—A Systematic Review  \nMariusz Tomaniak 1, *,†, Adrian Bednarek 1,† and Adrian Włodarczak 2,3  \nAcademic Editor: Roberto Pedrinelli  \nReceived: 14 November 2025  \nRevised: 14 December 2025  \nAccepted: 19 December 2025  \nPublished: 30 December 2025  \nCopyright: © 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.  \n1 First Department of Cardiology, Medical University of Warsaw, Banacha 1A, 02-097 Warszawa, Poland  \n2 Department of Cardiology, The Copper Health Centre (MCZ), 59-301 Lubin, Poland  \n3 Faculty of Medicine, Wroclaw University of Science and Technology, 50-981 Wroclaw, Poland  \n* [Correspondence: mariusz.tomaniak@wum.edu.pl](Correspondence: mariusz.tomaniak@wum.edu.pl)[ ](Correspondence: mariusz.tomaniak@wum.edu.pl)† These authors contributed equally to this work.  \nAbstract  \nBackground: Recent observational studies suggest that coronary sinus reducer (CSR) implantation may have a beneficial effect on microcirculatory indices in patients with coronary microvascular dysfunction (CMD). However, to date, there is no comprehensive summary of the evidence regarding the impact of CSR in this population. Methods: This systematic review was conducted in accordance with the PRISMA 2020 Statement. The following databases were searched: PubMed, EMBASE, MEDLINE, [and ClinicalTrials.gov. Studies](and ClinicalTrials.gov. Studies)[ ](and ClinicalTrials.gov. Studies)assessing microcirculatory indices or primarily involving patients with CMD undergoing CSR implantation were included. Results: After the selection process, 17 studies or trials were included in this systematic review. Across observational studies and case series, CSR implantation was associated with significant improvements in coronary microvascular function, including reductions in the index of microvascular resistance and an increase in coronary flow reserve. These physiological changes were accompanied by consistent improvements in angina severity (CCS class), exercise capacity, and quality-of-life measures, particularly in patients with more severe baseline CMD. Evidence was derived mainly from non-randomized studies involving small patient cohorts, with low procedural complication rates. Ongoing randomized trials are expected to clarify the magnitude of benefit and its clinical relevance in this population. Conclusions: CSR implantation may offer clinical and physiological benefits in patients with refractory angina due to CMD. However, the lack of randomized evidence and uncertainty regarding long-term effects warrant further adequately powered trials.  \nKeywords: coronary sinus reducer; coronary microvascular dysfunction; microvascular resistance; coronary physiology; ANOCA  \n1. Background  \nNearly 50% of patients presenting with anginal symptoms have no obstructive epicardial coronary artery disease [1] . In most cases, these symptoms result from coronary microvascular dysfunction (CMD), which leads to inadequate myocardial oxygen supply and is associated with poorer cardiovascular outcomes and reduced quality of life [1,2] . CMD can develop as a consequence of various underlying pathophysiological mechanisms; evidence suggests that fibrosis, oxidative stress, endothelial dysfunction, decreased vascular density, and excessive contractility of vascular smooth muscle may all contribute to disease development [3], particularly in the presence of comorbid conditions [4] . A wide  \nrange of underlying pathomechanisms hampers the development of molecular-targeted pharmacological solutions; thus, direct physiology modification has been introduced as a promising concept.  \nWhile optimization of antianginal therapy remains the first-line treatment in patients with angina caused by CMD—a condition previously referred to as a cardiac ","cbCaivMsc2KdfeuJ","https://ap.wps.com/l/cbCaivMsc2KdfeuJ","pdf",745899,16,"English","# Abstract\n## Background\n## Methods\n## Results\n## Conclusions\n# Background\n## Coronary microvascular dysfunction and angina\n## Coronary sinus reducer as a treatment option\n# Current Clinical Solutions for Patients with CMD\n## Diagnosis of CMD\n## Treatment domains","[{\"question\":\"What question does the systematic review address about coronary sinus reducer (CSR) in CMD-related refractory angina?\",\"answer\":\"It assesses the impact of CSR implantation on coronary biological and physiological function and summarizes evidence across completed and ongoing trials in patients with refractory angina caused by CMD.\"},{\"question\":\"How were studies selected in this review?\",\"answer\":\"The review followed PRISMA 2020 and searched PubMed, EMBASE, MEDLINE, and ClinicalTrials.gov for studies assessing microcirculatory indices or primarily including CMD patients undergoing CSR.\"},{\"question\":\"What outcomes were reported after CSR implantation across included studies?\",\"answer\":\"Observational studies and case series reported significant improvements in microvascular function, including reductions in microvascular resistance and increases in coronary flow reserve, along with consistent improvements in angina severity (CCS class), exercise capacity, and quality-of-life measures.\"}]","Coronary Sinus Reduction for Refractory Angina Caused by Microvascular Dysfunction - A Systematic Review | PDF",1790761868]