Coronary Sinus Reduction for Refractory Angina Caused by Microvascular Dysfunction-A Systematic Review.

Area of Science:

• Cardiology
• Interventional Cardiology
• Vascular Biology

Background:

• Coronary microvascular dysfunction (CMD) is increasingly recognized as a cause of angina.
• Observational studies suggest potential benefits of coronary sinus reducer (CSR) implantation for CMD.
• A comprehensive evidence summary on CSR for CMD was lacking.

Purpose of the Study:

• To systematically review the existing evidence on the impact of CSR implantation on microcirculatory indices and clinical outcomes in patients with CMD.

Main Methods:

• Systematic review conducted following PRISMA 2020 guidelines.
• Searched PubMed, EMBASE, MEDLINE, and ClinicalTrials.gov.
• Included studies assessing microcirculatory indices or patients with CMD undergoing CSR implantation.

Main Results:

• 17 studies/trials included; CSR implantation improved coronary microvascular function (reduced index of microvascular resistance, increased coronary flow reserve).
• Significant improvements observed in angina severity (CCS class), exercise capacity, and quality of life.
• Benefits were more pronounced in patients with severe baseline CMD; low procedural complication rates noted.

Conclusions:

• CSR implantation may offer clinical and physiological benefits for refractory angina due to CMD.
• Current evidence primarily from non-randomized studies with small cohorts.
• Further adequately powered randomized trials are warranted to confirm efficacy and long-term effects.