The use of the coronary sinus reducer for treating patients with refractory angina and diabetes mellitus: one-year outcomes from the REDUCER-I registry

Background/Introduction The coronary sinus Reducer (CSR) creates a focal narrowing in the CS and has demonstrated significant improvements angina in randomized studies, with an observed redistribution of blood flow to the subendocardial myocardium within ischemic myocardial segments. However, patients with refractory angina often have diabetes mellitus (DM), an independent predictor of repeat revascularization and mortality after percutaneous coronary interventions (PCI). Purpose To evaluate differences in the effects of CSR implantation on angina severity and quality of life in patients with and without DM in the real-world observational REDUCER-1 study. Methods 371 patients received the CS Reducer implant as part of the multicenter, non-randomized REDUCER-I study in 25 medical centers in Europe of which 175 had DM and 196 did not have DM (no-DM). This analysis included major adverse cardiac events (MACE), change in CCS class, and Seattle Angina Questionnaire (SAQ) scores at 12 months. Results There were no significant differences in the baseline demographics of the DM and no-DM cohorts; both were mostly male (DM 77.7% vs. no-DM 79.6%) with mean age 69.5±8.2 yrs (DM) vs. 68.7±10.7 yrs (no-DM). The majority of patients in both groups had a history of PCI (DM 74.9% vs. no-DM 73.0%) and a similar proportion of CCS class III/IV (DM 73.1% vs no-DM 68.4%). Through twelve months, DM and no-DM patients had similar rates of MACE (DM 8.9% vs no-DM 6.3%; p=0.4), which was primarily driven by the rates of MI (DM 6.6% vs. no-DM 4.7%). Both cohorts had significant improvements in all SAQ subscale measures at 12 months when compared to their baseline values, with no-DM patients having a greater improvement in SAQ quality of life scale (Figure 1). The distribution of CCS classes at 12 months was similar between DM and no-DM groups (p=0.55) with the proportion of patients remaining CCS class III/IV decreasing to 19.5% and 16.1% for the DM and no-DM cohorts, respectively. 71.0% of DM patients improved by greater than or equal to one CCS class at 12 months, which was similar to the 68.0% of no-DM patients with ≥1 CCS class improvement (p=0.66). Conclusion In this 12-month analysis of the REDUCER-I cohorts with and without diabetes, both groups of patients had similar and significant improvements in anginal symptoms and low rates of MACE after treatment with the CS Reducer. Despite the adverse prognosis for patients with diabetes following PCI compared with non-diabetic patients, no such disadvantage was shown following CS Reducer implantation, highlighting the potential utility of this device in such populations.