Refractory angina (RA) is a chronic condition (present for at least 3 months) of moderate-severe symptoms (Canadian class Cardiovascular Society [CCS] II-IV) due to coronary artery disease which cannot be adequately controlled by the combination of optimal medical therapy and coronary revascularization. The clinical impact in terms of quality of life, re-hospitalization and socio-health costs is extremely negative. In this context, the therapeutic goals are primarily the management of the symptom and improvement the patient's quality of life. The unpaid therapeutic demand of these patients has brought out a large number of medical and interventional treatments, including the coronary sinus reduction system (REDUCER). Numerous clinical studies and registries have been carried out and they proved both the efficacy and safety in the use of REDUCER. The physiological mechanism that are supposed to be behind the antianginal effect of coronary sinus intervention are essentially two:~Redistribution of coronary flow from the subepicardium to the subendocardium.~Coronary neoangiogenesis In both cases, the primum movens of the Reducer's therapeutic mechanism is attributable to the increase in venous pressure due to narrowing of the coronary sinus. Nevertheless, this mechanism of action is theoretical and has never been objectively tested. The evaluation of microcirculatory resistance by IMR before and after REDUCER implantation could be the most effective way to confirm this hypothesis.
The INROAD is an investigator-driven, prospective, study in which patients undergoing coronary sinus reducer implantation (Reducer) for chronic refractory angina undergo evaluation of the index of microcirculatory resistance (IMR) at the time of implantation, and at 4 months follow-up