[Coronary sinus reducer : Literature review and issues surrounding the France Reducer registry]

Coronary sinus Reducer implantation is a percutaneous technique used to treat patients suffering from refractory angina pectoris. The device narrows the coronary sinus, increases the back pressure in the myocardial venous system and forces redistribution of coronary blood flow from less ischemic subepicardium to the more ischemic subendocardium. Multiple clinical studies had proven its efficacy to alleviate myocardial ischemia and related symptoms, and to improve the quality of life of patients with refractory symptomatic chronic coronary artery disease for whom coronary revascularization is deemed unsuitable. This literature review aims to expose the device design, its mechanisms of action, and the clinical data supporting its use. Since November 2021 Reducer's reimbursement has been granted in France by the national health authority. It is the first device to be approved under a newly established reimbursement approval process. A transitional coverage is provided with opportunities for renewal before applying for full-time reimbursement. To fulfill the requirements of the National Commission for Evaluation of Medical Devices and Health Technologies, the French Society of Cardiology has been creating the France Reducer registry. This clinical registry has been collecting data from patients undergoing coronary sinus Reducer implantation regarding their clinical situation, periprocedural information, and one-year follow-up. It is crucial for the future of this emerging therapeutic option in France. To date, 215 patients from 28 centers have been included between June 2022 and September 2023.

Cardiac resynchronization therapy in patients with a coronary sinus reducer: a case series

Background

Reducing venous drainage of the coronary sinus is a promising intervention for refractory angina. Coronary Sinus Reducer (CSR) System™ effectively treats patients with refractory angina, possibly by increasing coronary collateral circulation, and leads to an improvement in their symptoms and quality of life. In patients with impaired left ventricular function and electrocardiographic dyssynchrony, cardiac resynchronization therapy (CRT) is an established treatment. However, there is only one published case report of CRT in a patient implanted with a CSR system. We present the first case series of CRT in patients implanted with the CSR system.

Case summary

This case series describes three patients. The first case demonstrated that CRT is feasible in patients implanted with a CSR system. The second case is the first report of a left ventricular lead extraction after CSR, and the third case was complicated due to the patient's medical history; however, CSR system implantation was feasible without major complications.

Discussion

Our results suggest that CRT is feasible in patients implanted with a CSR system, and lead extraction after CSR system implantation is possible. However, lead extraction in cases of severe adhesions around the CSR system and the coronary sinus may be associated with a high risk of complications; alternative options should be discussed at an early stage.

INOCA/ANOCA: Mechanisms and novel treatments

Angina or ischemia with no obstructive coronary disease (ANOCA/INOCA) is a common but under-treated condition due to poorly understood pathophysiologic mechanisms, limited diagnostic tools, and lack of proven targeted therapy. Coronary microvascular dysfunction (CMD) occurs when the microvasculature inadequately perfuses the myocardium under stress, or at rest in the case of microvascular spasm resulting in ANOCA/INOCA. Coronary functional angiography (CFA) measures endothelial independent microvascular dysfunction (coronary flow reduction <2.5) in response to adenosine and endothelial dependent microvascular dysfunction (lack of dilation and/or constriction) to acetylcholine testing as well as epicardial and microvascular spasm. Current treatment for coronary microvascular dysfunction is limited to renin-angiotensin system (RAS) inhibitors and statins as well as antianginal medications. Novel therapies targeting the underlying pathology are under development and include the coronary sinus reducer, CD34+ stem cell therapy, and novel pharmacologic agents such as sGC stimulators or endothelin-receptor blockers. We review the current understanding of pathophysiology, diagnostic tools, and novel therapies for coronary microvascular dysfunction in ANOCA/INOCA.

Implantation of the coronary sinus reducer for refractory angina due to coronary microvascular dysfunction in the context of apical hypertrophic cardiomyopathy-a case report

Background

Refractory angina leads to a poor quality of life and increased healthcare resource utilization. In this growing population of patients, multiple mechanism(s) of ischaemia may co-exist, including functional disorders of the coronary microcirculation. There are few evidence-based effective therapies resulting in a large unmet clinical need.

Case summary

A 38-year-old woman with refractory angina was referred with daily chest pain despite multiple anti-anginal medications and previous percutaneous coronary intervention. Cardiac magnetic resonance imaging demonstrated apical hypertrophic cardiomyopathy (HCM). Rubidium-82 positron emission tomography (PET) with regadenoson stress confirmed significant myocardial ischaemia in the apex and apical regions (16% of total myocardium) with a global myocardial perfusion reserve (MPR) of 1.23. Coronary angiography confirmed patent stents and no epicardial coronary artery disease. Therefore, the mechanism of ischaemia was thought attributable to coronary microvascular dysfunction (CMD) in the context of HCM. In view of her significant symptoms and large burden of left-sided myocardial ischaemia, a Coronary Sinus Reducer (CSR) was implanted. Repeat PET imaging at 6 months showed a marked reduction in ischaemia (<5% burden), improvement in global MPR (1.58), symptoms, and quality of life.

Conclusion

In refractory angina, ischaemia may be due to disorders of both the epicardial and coronary microcirculations. The CSR is a potential therapy for these patients, but its mechanism of action has not been confirmed. This report suggests that CSR implantation may reduce myocardial ischaemia and improve symptoms by acting on the coronary microcirculation. The efficacy of CSR in patients with CMD and its mechanism of action on the coronary microcirculation warrant further investigation.

Coronary Sinus Reducer: A Solution for patients with Refractory Angina

Refractory Angina (RA) places a great burden on patients and the healthcare system, with reduced quality of life (QOL), increased hospital admissions, polypharmacy, and psychological effects. Patients with RA are limited in options for management and with the introduction of the coronary sinus reducer (CSR), a safe and effective option may be available for this group of patients. This review article seeks to understand the efficacy of coronary sinus implantation in the current literature.

Efficacy of coronary sinus Reducer in patients with refractory angina and diabetes mellitus

Coronary sinus Reducer (CSR) implantation is currently recommended to relieve angina in patients with refractory symptoms despite optimal medical therapy and maximally achievable revascularization. The impact of diabetes mellitus on outcome after CSR implantation is at present unknown. We aimed to explore the impact of CSR in refractory angina patients with diabetes mellitus. Data from consecutive patients undergoing CSR implantation at four different centres between 2014 and 2018 were included. Patients were divided according to the presence or absence of diabetes mellitus. Primary objective of this analysis was to evaluate the clinical response to CSR implantation defined as an improvement of ≥ 1 classes of the Canadian Cardiovascular Society (CCS) Classification. A total of 219 patients were included, 116 (53%) of whom had diabetes mellitus. The median age of the population was 69 years and 167 patients (76%) were male. There were no significant differences between groups of patients with and without diabetes mellitus with respect to CCS class at baseline (p value = 0.32) and at follow-up (p = 0.75). Over a median follow-up of 393 [224-1004] days, 84 (72%) of the patients with diabetes mellitus met the primary outcome, similarly to those without diabetes mellitus (p = 0.28). Fifty-three patients (24%) did not have an improvement in CCS class and no one experienced worsening of angina. CSR implantation was equally effective in improving angina symptoms among patients with refractory angina and diabetes mellitus compared to patients without diabetes mellitus.

Safety and efficacy of coronary sinus narrowing in chronic refractory angina: Insights from the RESOURCE study

INTRODUCTION

Refractory angina (RA) is considered the end-stage of coronary artery disease, and often has no interventional treatment options. Coronary sinus Reducer (CSR) is a recent addition to the therapeutic arsenal, but its efficacy has only been evaluated on small populations. The RESOURCE registry provides further insights into this therapy.

METHODS

The RESOURCE is an observational, retrospective registry that includes 658 patients with RA from 20 centers in Europe, United Kingdom and Israel. Prespecified endpoints were the amelioration of anginal symptoms evaluated with the Canadian Cardiovascular Society (CCS) score, the rates of procedural success and complications, and MACEs as composite of all-cause mortality, acute coronary syndromes, and stroke.

RESULTS

At a median follow-up of 502 days (IQR 225-1091) after CSR implantation, 39.7% of patients improved by ≥2 CCS classes (primary endpoint), and 76% by ≥1 class. Procedural success was achieved in 96.7% of attempts, with 3% of procedures aborted mostly for unsuitable coronary sinus anatomy. Any complication occurred in 5.7% of procedures, but never required bailout surgery nor resulted in intra- or periprocedural death or myocardial infarction. One patient developed periprocedural stroke after inadvertent carotid artery puncture. At the last available follow-up, overall mortality and MACE were 10.4% and 14.6% respectively. At one, three and five years, mortality rate at Kaplan-Meier analysis was 4%, 13.7%, and 23.4% respectively.

CONCLUSIONS

CSR implantation is safe and reduces angina in patients with refractory angina.

Refractory Angina-Unsolved Problem

The article discusses pharmacologic and interventional therapeutic options for patients with refractory angina. Refractory angina refers to long-lasting symptoms (≥3 months) due to established reversible ischemia in the presence of obstructive coronary artery disease, which cannot be controlled by escalating medical therapy with second-line and third-line pharmacologic agents, bypass grafting, or stenting. Due to an aging population, increased number of comorbidities, and advances in coronary artery disease treatment, incidence of refractory angina is growing. Although the number of therapeutic options is increasing, there is a lack of randomized clinical trials that could help create recommendations for this group of patients.

Resynchronization therapy with His bundle pacing in a patient after coronary sinus reducer implantation

Symptomatic heart failure patients with ischemic heart disease may require both coronary sinus reducer (CSR) implantation due to refractory angina pectoris and cardiac resynchronization therapy (CRT). Optimal approach to CRT in these patients is unknown as CSR implantation in the distal coronary sinus could deter left ventricular lead placement and thus preclude conventional CRT with biventricular pacing. We present a 70-year-old patient with ischemic cardiomyopathy and wide QRS complex after CSR implantation in whom we achieved successful cardiac resynchronization with His bundle pacing (HBP). HBP led to acute improvement in hemodynamic parameters and exercise capacity that persisted at follow-up. This case represents the first description of successful CRT with HBP in a patient after CSR implantation. HBP could present a feasible and safe resynchronization approach in these patients. <Learning objective: Optimal approach to cardiac resynchronization therapy in patients after coronary sinus reducer (CSR) implantation remains unknown as CSR implantation in the distal coronary sinus may deter left ventricular lead implantation and thus preclude conventional biventricular pacing. His bundle pacing could present a feasible and safe resynchronization approach in this growing group of patients.>.

Implantation of a Coronary Sinus Reducer to Treat Refractory Angina in a 38-Year-Old with an Anomalous Left Coronary Artery and No Revascularization Options

A 38-year-old female with anomalous left coronary artery from the pulmonary artery presented with refractory angina (Canadian Cardiovascular Society [CCS] class 4). Having failed two previous internal mammary artery grafts to the left anterior descending artery and with no percutaneous revascularization options, she underwent coronary sinus reducer implantation, which improved her symptoms (CCS 0), quality of life, and corresponded to an improvement in ischemia on myocardial perfusion scanning. This case report describes an unusual case of refractory angina in the context of congenital heart disease, illustrates the benefit of this novel hourglass-shaped stent in improving ischemia, quality of life, depression and anxiety, and highlights the importance of managing these patients in multidisciplinary teams.

Angina and left ventricular dysfunction: can we 'reduce' it?

Despite the evolution in pharmacology and devices, recurrent and persistent angina still represent a frequent issue in clinical practice. A 69-year-old Caucasian female patient has history of surgical aortic valve replacement with a bioprosthesis for severe aortic stenosis with subsequent transcatheter valve-in-valve implantation for bioprosthesis degeneration and single coronary artery bypass graft with left internal mammary artery on left anterior descending (LAD). After transcatheter aortic valve implantation, she started to complain angina [Canadian Cardiovascular Society (CCS) Class III], effectively treated with bisoprolol uptitration and ivabradine 5 b.i.d. addition. After 6 months, she had a non-ST segment elevated myocardial infarction with evidence of left main occlusion and good functioning aortic bioprosthesis. A retrograde drug-eluting balloon percutaneous coronary intervention (PCI) on LAD (in-stent restenosis) was performed. However, the patient continued to complain angina (CCS Class II–III), even after further ivabradine increase to 7.5 mg b.i.d. After 4 months, the patient underwent Reducer implantation. After 2 months, angina started to improve and the patient is currently angina free. In the last decades, PCI materials and stents greatly improved. Medical therapy (such as β-blockers) has been shown not only to improve symptoms but also to add a prognostic benefit in patients with reduced ejection fraction (EF). Ivabradine showed additional benefits in patients with angina and reduced EF. However, still a relevant portion of patients complain refractory angina. The COSIRA trial showed that a coronary sinus Reducer was associated with greater angina relief than the sham procedure and could be a further step in angina treatment.