Clinical Research Directory

Inclusion Criteria: 1. Ability to give informed consent to the study. 2. Age ≥ 18 years and ≤ 75 years. 3. Diagnosis of MB during index coronary angiography\*. 4. Symptoms or signs of inducible ischemia (if signs, these should involve the territory of the index vessel). Angiographic definition of MB \* Myocardial bridge is a congenital anomaly characterized by an intramural course of an epicardial coronary segment. This anatomical arrangement causes the artery to be squeezed during systole, with a relaxation in diastole. In this study, MB is defined as a visual ≥ 50% reduction in the minimal luminal diameter during systole and a complete or partial relaxation in diastole ("milking effect"). The use of intracoronary vasodilators (i.e., nitrates) can increase the systolic narrowing of the vessel, through a reflex rise of the adrenergic drive, and consequently the angiographic sensitivity in detecting MB. Exclusion Criteria: 1. Moderate to severe CAD (≥ 50% stenosis in any vessel, including chronic total occlusion) at the time of enrolment/randomization. 2. Previous CABG involving the index vessel. 3. Severe valvular heart disease. 4. Left ventricular systolic dysfunction \[ejection fraction (EF) \< 40%\], regardless of the etiology. 5. Clinically significant right ventricular dysfunction. 6. Known severe renal impairment (eGFR \< 30 ml/min/1.73 m2). 7. Known severe hepatic impairment, or history of cirrhosis with evidence of portal hypertension. 8. History of malignancy of any organ system with a life expectancy \< 1 year. 9. Any previous history of ischemic stroke, intracranial haemorrhage or disease (neoplasm, arteriovenous malformation, aneurysm). 10. Pregnant or breastfeeding women. 11. Known hypersensitivity or contraindication to any of the drugs used for coronary physiology testing (nitrates, adenosine, dobutamine, acetylcholine).