Could a blood pressure drug ease chest pain in people with clear arteries?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Clinical diagnosis of symptomatic angina, defined as the presence of substernal chest pain or discomfort provoked by exertion or emotional stress and relieved by rest and/or glyceryl trinitrate (nitroglycerin). 2. Age 18 years or older. 3. Able and willing to provide written informed consent. 4. Able and willing to adhere to study procedures and follow-up requirements. Exclusion Criteria: 1. Symptoms consistent with unstable angina, including: 2. Angina at rest lasting more than 20 minutes. 3. New-onset severe angina. 4. Angina increasing in frequency, duration, or occurring at a lower threshold. 5. Angina occurring following a recent myocardial infarction. 6. Known significant coronary artery disease, defined as previous investigations demonstrating greater than 50% epicardial coronary artery stenosis. 7. Uncontrolled hypertension, defined as clinic blood pressure greater than 140/90 mmHg despite treatment with three or more antihypertensive medications. 8. Pregnancy or breastfeeding. 9. Poorly controlled asthma as defined in the study protocol. 10. Severe heart failure or symptoms of active heart failure. 11. Significant chronic kidney disease, defined as estimated glomerular filtration rate (eGFR) less than 30 mL/min/1.73 m². 12. Clinical evidence of active infection at the time of recruitment. 13. Significant liver disease, defined as Child-Pugh Class B or C liver disease (or worse than Child-Pugh Class A). 14. Systolic blood pressure less than 90 mmHg at the time of recruitment. 15. Previously documented allergy or hypersensitivity to endothelin receptor antagonists. 16. Concurrent use of medications contraindicated with endothelin receptor antagonist therapy. 17. Requirement for invasive coronary angiography for another clinical indication, including but not limited to valvular heart disease assessment or intervention.