ORBITA COSMIC: Coronary sinus reducer did not improve transmural myocardial perfusion but angina symptoms

By John Vitarello on

Key Points

– Coronary sinus reduction (CSR) is a potential therapeutic device for patients with refractory angina
– In this first-of-its-kind randomized, placebo-controlled, double-blind trial, participants underwent CSR implantation or a placebo procedure, with pre- and post-trial CMR and daily angina reporting
-Participants who received a CSR reported fewer episodes of angina, but CMR did not demonstrate improved blood flow

Angina refractory to revascularization and anti-anginal medication is a challenging clinical scenario. Coronary sinus reduction (CSR) has emerged as a potential therapeutic. Up to this point, there has never been a randomized, placebo-controlled, double-blind trial evaluating the effectiveness of CSR.

This percutaneous procedure deploys an hourglass shaped stent that Is balloon-expanded once in the coronary sinus. In theory, this creates higher back pressure in the coronary arteries thereby improving blood flow and reducing angina. Dr. Rasha Al-Lamee from Imperial College London shared her findings at ACC 2024.

The ORBITA-COSMIC trial enrolled 51 patients in the United Kingdom with refractory angina on maximally tolerated anti-anginal and without available revascularization options to be randomized to a CSR or placebo. The placebo procedure relied on sedation and access to the internal jugular to perform a coronary sinus venogram, but no implant.  Participants reported symptoms daily via a phone application. They also underwent a cardiac MRI and treadmill exercise test before the procedure and then six months later. The primary endpoint was myocardial blood flow as measured by CMR using adenosine and the primary symptom endpoint was frequency of angina. Secondary outcomes examined angina assessed by questionnaire, an exercise test, and other aspects of CMR including subendocardial to subepicardial stress.

A total of 61 patients were enrolled (86% male) and were randomized to either CSR ( n=25) or placebo (n=26). Of these 50 were included in the intention to treat analysis. A total of 57% ( 454 of 800) of imaged cardiac segments were ischemic at enrollment, with a median stress myocardial blood flow of 1.08 ml/min per g (IQ 0.77-1.41). The primary imaging outcome, myocardial blood flow, was not significantly different between the two groups (0.06ml/min/g, 95% CI -0.09 to 0.20) although a secondary imaging outcome, subendocardial to subepicardial stress myocardial blood flow, improved with CSR. Participants with CSR reported 40% fewer anginal episodes (OR 1.40, 95% CrI 1.08 to 1.83), although this did not translate into a significant improvement in treadmill exercise time.

In summary, in this randomized, placebo controlled, double-blind study, CSR improved angina frequency without improvement in transmural myocardial perfusion measured by CMR.