Impact of coronary sinus reducer on coronary microcirculation in refractory angina

Abstract Introduction Despite significant advances in the management of Coronary Artery Disease (CAD), refractory angina (RA) remains a considerable clinical problem. RA is a chronic condition (lasting more than 3 months) characterized by anginal symptoms that impair quality of life despite optimal medical therapy (OMT) and available coronary revascularization. RA affects up to 10% of CAD patients and has a substantial impact on the healthcare system. The pathophysiology of RA is not fully understood and is more complex than the traditional model of oxygen supply-demand imbalance resulting from vessel obstruction. Coronary microvascular dysfunction (CMD) appears to be an important etiological factor. CMD can be assessed using invasive coronary angiography to measure the index of microcirculatory resistance (IMR) and coronary flow reserve (CFR). Recent studies have confirmed the efficacy of the Coronary Sinus Reducer for patients with advanced RA who are not candidates for revascularization [1]. Consistent with existing data suggesting a potential impact of CSR on coronary microcirculation [2,3,4,5], this pilot study was designed to assess the effect of CSR implantation on coronary microvascular function. Purpose To evaluate the impact of coronary sinus reducer (CSR) device implantation on coronary microcirculation function, specifically the index of microcirculatory resistance (IMR) and coronary flow reserve (CFR). Methods This prospective study enrolled patients with RA (at least CCS class II) despite optimal medical therapy (OMT) and confirmed CMD (CFR <2.5 and/or IMR >25). Six months after CSR implantation, subjects underwent clinical evaluation, including assessment of angina severity, followed by heart catheterization to assess potential changes in CFR and IMR. Results In 25 patients, predominantly men (73.3%), significant improvements were observed in absolute CFR (1.99 [0.66] vs. 3.06 [1.18], p <.001) and absolute IMR (36.64 [17.64] vs. 21.68 [12.24], p <.001). 24 out of 25 patients reported reduction in their CCS class by at least one class. One non-responder was identified. Conclusions The results of this pilot study suggest that Coronary Sinus Reducer implantation has a positive impact on coronary microcirculation function and could become a novel therapeutic approach for subjects with coronary microvascular dysfunction and co-existing refractory angina pectoris.CFR and IMR baseline and 6M follow upFor image description, please refer to the figure legend and surrounding text. CCS Class changesFor image description, please refer to the figure legend and surrounding text.