Refractory angina pectoris refers to long-lasting symptoms (3 months and longer) due to established reversible ischemia in the presence of obstructive coronary artery disease, which cannot be controlled by escalating medical therapy with the use of second- and third-line pharmacological agents, bypass grafting, or stenting including percutaneous coronary intervention (PCI) of chronic total coronary occlusion. The coronary sinus reducing stent (CSRS) is designed to create a focal narrowing in the lumen of the coronary sinus.

This report updates the previous report from 2020. For the analysis of effectiveness no new studies could be identified in the update search. Therefore, the effectiveness results and conclusions rely solely on the evidence presented in the 2020 report, which included one RCT comparing CSRS with a sham procedure with 104 patients. Endpoints with a statistically significant difference (CSRS vs. sham procedure) were: an increase in Canadian Cardiovascular Society (CCS) angina score of at least two classes at six months, a one class increase in CCS angina score, an overall mean reduction in CCS class, and an increase in quality of life as measured by the Seattle Angina Questionnaire (SAQ). SAQ treatment satisfaction, overall increase in exercise duration, and increase in the Wall Motion Index, on the other hand, were not statistically significant. For the safety analysis, three prospective single-arm studies were newly identified in the course of the update. The currently available evidence on the safety of the CSRS thus consists of the aforementioned RCT and nine observational studies. In the RCT, fewer serious adverse device events (SADEs) occurred in the intervention group (19%) than in the control group (46%). In the observational studies, the rate of SADEs (most common: deaths and stable angina) varied between 0% and 30%.

Results from well-designed RCTs are lacking to clarify the role of CSRS in clinical practice. Results from ongoing studies are awaited. CSRS has the potential to fill a therapeutic gap and, based on current knowledge, has a positive safety profile. However, there is a lack of knowledge about the exact mechanism of action and a long-term safety profile.