CSR cuts angina episodes in patients with no further antianginal options

In the placebo-controlled ORBITA-COSMIC* trial, an implantable coronary sinus reducer (CSR) does not increase transmural myocardial perfusion, but it reduces the frequency of angina and improves quality of life (QoL) in patients with no further antianginal options.

“The improvement in angina took 10 weeks to manifest and was sustained through follow-up,” reported lead investigator Dr Michael Foley, Imperial College London, UK at ACC.24. 

There was no benefit to CSR over placebo in stress myocardial blood flow to ischaemic segments of the heart, but subendocardial perfusion improved with CSR.

Fifty patients with coronary artery disease ineligible for percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) surgery were enrolled in the trial. Over 90 percent presented with Canadian Cardiovascular Society class III or IV angina.

The study was done at six hospitals in the UK. All patients underwent adenosine-stress cardiac magnetic resonance with perfusion mapping. A smartphone application (ORBITA) was used to record daily angina episodes for 6 months. The patients also completed symptom and QoL questionnaires. [Lancet 2024;403:1543-1553]

More angina-free days at 6 months

At 6 months, the likelihood of having angina-free days increased by 40 percent in those assigned to CSR (odds ratio [OR], 1.40, 95 percent confidence interval [CI], 1.08–1.03). Statistical probability was calculated at 99.4 percent.

Patients implanted with the device had 13 more angina-free days than those assigned to placebo (84.5 vs 71.5 days).

The improvement in angina control correlated with improvement in QoL. The Seattle Angina Questionnaire (SAQ) angina frequency and MacNew heart disease health-related QoL scores improved with CSR. “Both were statistically significant and clinically meaningful,” according to Foley.

“Despite the reduction in angina, no benefit of CSR was detected in stress myocardial blood flow in segments designated as ischaemic at enrolment,” he added.

Myocardial perfusion reserve and myocardial blood flow at rest were negative for CSR advantage. However, Foley said the probability of improvement in the endocardial-to-epicardial ratio in ischaemic segments was at 98.2 percent.

Other than the inability to deploy CSR in one patient, no other periprocedural complications were observed. Two patients in the experimental arm vs none in the placebo arm developed a CSR embolization. There were no bleeding events, stroke, or myocardial infarction.

At the study end, there was no difference in treadmill exercise time between the study arms. Foley said functional improvements are unlikely for these patients who were no longer responding to antianginal medications, had multiple comorbidities, and were extremely limited in their activity level.

“Despite maximal antianginal therapy, almost all patients had class III or IV angina with no further treatments available for symptom control,” Foley added.

He said a CSR device might be the only practical option for these patients – something that would reduce their anginal episodes and improve QoL so they feel better.