Background <p>Coronary chronic total occlusion (CTO) is a common cause of refractory angina, and impaired quality of life. Coronary sinus reducer (CSR) implantation is a safe and effective therapy for patients with refractory angina.</p> Aim <p>To evaluate the clinical efficacy of reducer implantation to relieve angina in patients with CTO.</p> Methods <p>Patients with refractory angina and no option for revascularization who underwent Reducer implantation between 2011 and 2023 were included. Angina symptoms, physical capacity, and quality of life were evaluated at baseline, 6&#xa0;months, and 1&#xa0;year following reducer implantation. Clinical outcomes were compared between patients with and without CTO.</p> Results <p>Overall, 262 patients (70 ± 11&#xa0;years old, 24% female) underwent reducer implantation, and 131 (50%) had CTO. Among the entire population, 77% of patients had improvement of at least 1 CCS class following reducer implantation, and 42% reported improvement of ≥ 2 grades of CCS at 1&#xa0;year. Median 6MWT increased from 300&#xa0;m (IQR 218–382) to 358&#xa0;m (IQR 275–419) 6&#xa0;months following reducer implantation, and all 5 domains of the SAQ improved (<i>p</i> &lt; 0.001 for all). The degree of improvement in angina severity as well as in quality of life was similar for patients with and without CTO except for better improvement in 6MWT distance among patients without CTO. Patients with CTO of the right coronary artery showed similar improvement following reducer implantation.</p> Conclusions <p>Reducer implantation is similarly beneficial for patients with refractory angina due to both CTO and non-CTO lesions. Randomized prospective studies are needed to evaluate the optimal therapeutic approach in these patients.</p> Graphical Abstract <p>Change of CCS angina score class in patients with and without CT 1&#xa0;year following reducer implantation. CCS, Canadian Cardiovascular Society</p> <p></p>