Coronary Sinus Reduction for Refractory Angina
Redistribute flow. Relieve pain. Restore hope. Millions of patients with coronary artery disease (CAD) suffer from chronic angina despite receiving optimal medical therapy. Shockwave Reducer is designed to improve the symptoms of chronic angina through a permanent, controlled narrowing of the coronary sinus.*
Creating Better Outcomes: Percutaneous Treatment Option for Chronic Angina
Usually a symptom of myocardial ischemia (a lack of blood flow to the heart muscle), angina may feel like pressure or squeezing in the chest and/or pain in the shoulders, arms, neck, jaw or back. Many patients experiencing angina suffer symptoms that are severe, long-lasting and uncontrollable by traditional medical therapies. This severely debilitating condition is known as refractory, or chronic, angina.
- Angina pain is often a symptom of CAD, when plaque buildup occurs in the arteries supplying the oxygen-rich blood to the heart, forcing the heart to work harder.
- Many patients can get relief from their angina through revascularization from a coronary intervention or surgery. However, 25–40% continue to suffer from angina even after successful revascularization.1, 2
- Angina with nonobstructive coronary arteries (ANOCA) is increasingly recognized and may affect nearly one-third of patients undergoing invasive coronary angiography for suspected CAD.3, 4 These patients do not have plaque buildup as a cause for their angina, and currently have limited options.
Real-World Impact Backed By Clinical Data
Shockwave Reducer delivers effective angina relief for patients whose symptoms cannot be controlled through traditional therapies – and it’s been proven by rigorous clinical data, including randomized sham-controlled trials. Learn how our clinically validated therapy is reducing pain and restoring hope for millions of patients.
Accordion Section
REDUCER-I 12-month results demonstrated the safety and efficacy of the Reducer in improving angina severity and quality of life in patients suffering from chronic angina. Additionally, the outcomes showed a reduction in emergency department visits after Reducer implantation as well as clinically significant increase in the 6 Minute Walk Test distance.
- Canadian Cardiovascular Society Class (CCS) was significantly better compared to baseline (p<0.001).†
- 71% of patients improved one or more CCS angina classes at 12 months.†
- 26% of patients improved two or more CCS angina classes at 12 months.†
The treatment effect was durable; interim analysis showed improvements in CCS class and Quality of Life (QoL) were sustained through 3 years.6
REDUCER-I sub-analysis of patients with non-obstructive CAD** receiving a Reducer device showed a statistically significant improvement in QoL and an improvement in CCS class at 12 months.7
Non-obstructive CAD defined as less than 70% stenosis by visual estimate in all major epicardial coronary arteries.
- Both obstructive and non-obstructive CAD cohorts had significant improvements in Mean Seattle Angina Questionnaire (SAQ) Summary Score at 12 months:
- Obstructive CAD: Mean SAQ Summary Score 52.9 ± 17.2 at baseline/69.1 ± 17.2 at 12 months (p<0.0001).
- Non-obstructive CAD: Mean SAQ Summary Score 51.0 ± 17.8 at baseline/60.8 ± 19.9 at 12 months (p<0.0002).
- Both obstructive and non-obstructive CAD cohorts had improved CCS class at 12 months with no significant differences between the groups:
- ≥1 CCS class improvement (p=0.11): Obstructive CAD 71.7% (162/226), non-obstructive CAD 60.3% (35/58).
- ≥2 CCS class improvement (p=0.17): Obstructive CAD 26.7% (59/226), non-obstructive CAD 17.2% (10/58).
REDUCER I sub-analysis of patients with Diabetes Mellitus (DM) showed similar improvement in angina reduction (change in CCS), similar QoL improvements and no difference in MACE-free survival at 12 months than the patients without history of DM.8
- Patients with and without DM showed similar CCS class improvement (DM 71%, without DM 68% – for ≥1 CCS class ; p=0.66).
- Patients with and without DM showed similar QoL improvements in the mean SAQ summary score at 12 months (DM 17.4, without DM 19.9; p=0.27).
REDUCER I sub-analysis of female and male patients showed similar, significant improvement in angina reduction (change in CCS), significant vs baseline and no difference in MACE-free survival at 12 months among both cohorts.9
- Both female and male cohorts had improved CCS class at 12, 24, and 36 months with no significant differences between the groups (female 86%, male 75% at 36 months), except at 6 months, favoring females (p=0.03).
- Both female and male cohorts had significant SAQ summary score improvement at 12 months (female improved by 22.6±20.7 vs male 17.6 ±19.4; p<0.001).
Download sex specific sub-analysis data
*REDUCER I is a Shockwave Medical-sponsored trial.
**CAD = coronary artery disease
†Paired analysis for those with both baseline AND 12 month CSS class assessment.
Results of the independent ORBITA-COSMIC trial show Shockwave Reducer lessens angina frequency and improves heart disease related quality of life while improving subendocardial perfusion. 51 patients were randomized at six centres in the UK. Shockwave Reducer decreased the number of daily angina episodes compared to placebo at six months.
- The results showed evidence of benefit on SAQ angina frequency reported using the smartphone ORBITA-app in the coronary sinus reducer (CSR) group compared to the placebo group [16.0 (95% CrI 5.1 to 27.3) Pr(Benefit)=99.7%].
- MacNew Heart Disease Health-Related Quality of Life scores improved in the CSR group compared with the placebo group [Placebo-controlled increment 0.60 (95% CrI 0.15 to 1.06) Pr(Benefit)=99.4%].
- While the primary imaging endpoint showed no improvement in transmural myocardial perfusion (difference 0.06 mL/min/g; 95% CrI −0.09 to 0.20; Pr[benefit]=78.8%), ORBITA‑COSMIC demonstrated a significant improvement in subendocardial perfusion, reflected by an increase in the endocardial‑to‑epicardial stress myocardial blood flow ratio (+0.09 in ischaemic segments; 95% CrI 0.00 to 0.17; probability of benefit 98.2%), supporting the theorized mechanism of action of the Shockwave Reducer.
Beginning in 2010, the Reducer team and clinicians worldwide began studying the safety and effectiveness of the Shockwave Reducer device. 104 patients with Canadian Cardiovascular Society (CCS) class III or IV angina and myocardial ischemia who were not candidates for revascularization were enrolled. One randomized group received the device (treatment group) while another received a sham procedure (control group). COSIRA** demonstrated patients receiving the Shockwave Reducer device achieved a statistically significant improvement in angina symptoms and quality of life compared to patients in a sham control group.
- 71% of Reducer treatment group had ≥1 CCS angina classes improvement at 6 months compared to 42% in the control group (p=0.003).
- 35% of Reducer treatment group had ≥2 CCS angina classes improvement at 6 months compared to 15% in the control group (p=0.02).
- Quality of life improved 17.6 points for patients who received the implant, vs. 7.6 points for patients in the control group (p=0.048).
*COSIRA is a Shockwave Medical-sponsored trial.
**COSIRA = COronary SInus Reducer for treatment of Refractory Angina
Building on Clinical Data: COSIRA II Study
Currently enrolling: COSIRA** II is the next-phase clinical trial designed to gather further evidence of the safety and effectiveness of Shockwave Reducer. The study is a U.S.-based, multicenter, randomized, double-blind, sham-controlled trial. ClinicalTrials.gov Identifier: NCT05102019.
**COSIRA = COronary SInus Reducer for treatment of Refractory Angina
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COSIRA II Symposium: The Coronary Sinus Reducer
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COSIRA II Symposium: Angina: The Scope of the Challenge
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COSIRA II Symposium: The Future of Clinical Data for the Reducer
The physicians featured are paid consultants for Shockwave Medical.
*Shockwave Reducer is commercially available in select European countries and has been implanted in over 3,500 patients. It is currently under clinical investigation in the U.S.
Caution: In the United States, Shockwave Reducer is an investigational device, limited by United States law to investigational use. The Reducer is subject of Investigational testing and is being studied in the COSIRA-II trial in Canada.
Shockwave Reducer is commercially available in certain countries outside the U.S. and Canada. Please contact your local representative for specific country availability. Prior to use, please reference the Instructions for Use for more information on warnings, precautions and adverse events: ifu.sw-reducer.com
1: Abdallah, M. J Am Coll Cardiol 2017;69:2039-50.
2: Stone, G. 2-year results from the ABSORB IV randomized trial. TCT 2019.
3: Patel, M. N Engl J Med 2010; 362:886-895.
4: Samuels, B. J Am Coll Cardiol 2023; 82:1245-1263.
5: Verheye S, et al. Coronary sinus narrowing for the treatment of refractory angina: one-year results of the REDUCER-I study. EuroIntervention. 2025 Aug 4;21(15):e879-e881.
6: Verheye et al. Coronary Sinus Narrowing for Treating Refractory Angina. REDUCER-I Multicenter “Real-World” Observational Study Primary Endpoint Analysis. JACC Cardiovasc Interv. 2024;17:2908-18.
7: de Silva, R, van de Hoef, T, van Kuijk, J. et al. Coronary Sinus Reduction for REDUCER-I Patients With Refractory Angina and Angiographically Nonobstructive Coronary Artery Disease. JACC Adv. 2026 Apr, 5 (4).
8: de Silva, R. Presented at ESC 2025.
9: Verheye, S. Presented at TCT 2025.
10: Foley et al. The Lancet. 2024 Apr 8; https://doi.org/10.1016/S0140-6736(24)00256-3.
11: Verheye S, Jolicoeur EM, Behan MW, et al. Efficacy of a device to narrow the coronary sinus in refractory angina. N Engl J Med 2015; 372: 519-527.