Design and rationale of the efficacy of endothelin receptor antagonism in treatment of coronary artery spasm: a randomized controlled trial (EDIT-CAS)

Background: Patients with angina and no obstructive coronary artery disease frequently have vasomotor dysfunction as the underlying mechanism for symptoms. Patients with vasomotor dysfunction have a high angina burden and their treatment frequently fails to reduce complaints sufficiently. Targeted therapies are currently unavailable due to heterogeneity in the patient population and incomplete understanding of the underlying pathophysiological mechanisms. One of the vasomotor dysfunction endotypes, epicardial spasm, is hypothesized to be a possible target for endothelin receptor antagonism treatment. Methods: The EDIT-CAS trial is a registry based, double blind, randomised, placebo-controlled clinical trial and aims to compare the efficacy of 10 weeks of add-on bosentan treatment versus placebo to prevent epicardial spasm at repeat spasm provocation test. Secondary and explorative outcomes are the effect on anginal complaints, safety of bosentan treatment, changes in coronary reactivity and the relationship between baseline endothelin levels and treatment success. We will include 100 patients with previously diagnosed epicardial vasospasm on a maximal triggering dose of 100 micrograms of acetylcholine and continuing angina(-like) symptoms at least weekly despite optimal medical treatment. Trial registration: The is registered in Clinical Trials Information System (2023-507782-25-00) and ClinicalTrials.gov (NCT06432452).