REMEDY-PILOT: First Sham-Controlled Study Shows No Improvements after Coronary Sinus Reducer in Patients with Refractory Angina and Unobstructed Coronary Arteries
SAN DIEGO – Coronary sinus reducer (CSR) implantation was safe but did not significantly improve myocardial perfusion reserve (MPR), patient-reported symptoms, or quality of life in patients with coronary microvascular dysfunction (CMD) and refractory angina without significant obstruction of the major coronary arteries. These findings come from the first randomized, double-blind, sham-controlled trial to evaluate the procedure’s efficacy and feasibility in this population.
Findings were reported today at TCT® 2026, the annual scientific symposium of the Cardiovascular Research Foundation® (CRF®). TCT is the world’s premier educational meeting specializing in interventional cardiovascular medicine.
CMD is a major cause of angina with nonobstructive coronary arteries (ANOCA), yet evidence-based treatment options remain limited. In patients with obstructive coronary artery disease, CSR implantation has been shown to improve symptoms and quality of life by redistributing myocardial blood flow (MBF) at the level of the microcirculation. However, its effectiveness in patients with CMD remains unknown.
Between May 2023 and February 2026, 54 patients (24 women and 30 men) with refractory angina, unobstructed coronary arteries and reduced MPR were randomized in the trial. Ninety percent were in CCS class III/IV despite taking a median of four anti-anginal medications. After deep conscious sedation together with auditory and visual isolation, participants were randomized 1:1 to CSR implantation or a sham procedure, with blinded follow-up continuing for six months.
The primary endpoint was the change in segmental endocardial MPR after six months, and CSR did not result in improvement in this perfusion metric [adjusted treatment effect: -0.03 (95% CI, -0.22 to 0.15), p=0.72]. Some of the key secondary endpoints were also not significantly different between groups, including endocardial to epicardial ratio at stress which had an adjusted relative treatment effect of 1.004 (95% CI: 0.954 to 1.057, p=0.88) and patient-reported number of daily angina episodes for which the estimated odds ratio was 0.92 [95% CrI 0.42 to 2.04, Pr(Benefit)=0.41]. CCS class was slightly improved for those who received CSR [odds ratio: 0.30 (95% CI: 0.10-0.87), p=0.03], but there were no significant differences in Seattle Angina Questionnaire domains between groups.
“Although CSR implantation was safe, the data showed no significant improvement in CMR perfusion metrics, symptoms, or quality of life compared with a sham procedure in these patients, who currently have no other evidence-based treatment options,” said Kevin Cheng, MA, BM BCh, MRCP, British Heart Foundation Clinical Research Fellow, National Heart & Lung Institute at Imperial College London.
“We will complement these primary results by reporting data from invasive coronary thermodilution performed as part of a pre-specified mechanistic substudy nested within REMEDY-PILOT,” said Ranil de Silva, PhD, FRCP, Chief Investigator of REMEDY-PILOT, National Heart & Lung Institute at Imperial College London. “Additional randomized, double-blind, placebo-controlled studies will be needed to confirm these results and define whether there is a role for Reducer therapies for patients with CMD.”
The study was funded by the British Heart Foundation with grants from Shockwave Medical (J&J) and Abbott Vascular who had no role in study design, conduct, analysis or reporting.
Dr. Cheng reported the following disclosures: grant/research support from the British Heart Foundation and honoraria from Johnson & Johnson MedTech.
Dr. de Silva reported the following disclosures: grant/research support from the British Heart Foundation, Johnson & Johnson MedTech and Abbott Vascular. Consultant fees/honoraria/speaker’s bureau from Johnson & Johnson MedTech and Spectrawave.
The results of the study were presented on Sunday, November 1 at 11:51 AM PT in the Main Arena at the San Diego Convention Center during TCT 2026.
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