A coronary sinus reducer may help alleviate angina but might not increase blood flow to the heart, according to recent study findings.

Coronary sinus reducers are designed to narrow the vein collecting blood from the coronary sinus to direct oxygen-rich blood into areas of the coronary sinus receiving limited blood.

In the ORBITA-COSMIC study, which was presented by Foley et al at the American College of Cardiology (ACC) Annual Scientific Session 2024 and simultaneously published in The Lancet, researchers randomly assigned 51 patients with symptomatic refractory angina, ischemia, and coronary artery disease to undergo either a coronary sinus reducer implantation or a placebo procedure. The participants also tracked their symptoms daily and partook in cardiac magnetic resonance imaging (MRI) and treadmill exercise tests prior to their procedures and after a follow-up of 6 months.

At the end of the study period, the patients who received the coronary sinus reducer were 40% more likely to report a reduction in daily angina episodes compared with those who underwent the placebo procedure. The patients in the coronary sinus reducer group also had lower angina frequency based on the Seattle Angina Questionnaire and experienced improvement in their subendocardial to subepicardial ratio of stress myocardial blood flow. However, there were no statistically significant differences in blood flow to the heart or treadmill exercise time between the two groups.

Further studies may be needed to determine which patients are more likely to benefit from cardiac sinus reducers.

“We don’t have a positive endpoint in terms of the primary hypothesis of how this device works, but it does seem to reduce angina frequency in patients with refractory angina,” concluded senior study author Rasha Al-Lamee, MBBS, PhD, a clinical academic interventional cardiology consultant at Imperial College Healthcare National Health Service Trust and a clinical reader at Imperial College London.