Abstract 12216: Prevalence of Coronary Microvascular Dysfunction in Patients With Angina and Known Myocardial Bridge

Abstract

Introduction: Myocardial bridges are prevalent in patients with and without angina and can present a diagnostic dilemma when evaluating angina. Coronary microvascular dysfunction (CMD) is an important cause of chest pain in patients presenting with angina without obstructive CAD. The prevalence of concomitant CMD and myocardial bridge is not well described. Methods: All patients with known myocardial bridge and chest pain who underwent cardiac catheterization with bridge study at the University of Chicago Medical Center between 2020-2021 were included. All patients underwent pharmacologic testing with dobutamine with measurement of resting flow reserve (RFR). Abnormal RFR was defined as < 0.8. Some patients additionally underwent coronary physiology study with adenosine (Ado) and/or acetylcholine (Ach) with determination of coronary flow reserve (CFR), index of microvascular resistance (IMR), and spasm (for Ach). Abnormal endothelial dependent microvascular function was defined as CFR < 1.5 or IMR > 31 on Ach testing. Abnormal endothelial independent microvascular function was defined as CFR < 2.0 or IMR > 25 on Ado testing. Results: A total of 27 patients (mean age 47 + 9, 60% female) were studied. There were 18 patients with hemodynamically significant bridge of whom 13 underwent surgical unroofing and 9 patients with hemodynamically insignificant bridge of whom 3 underwent surgical unroofing. There was no significant difference in rates of endothelial dependent or independent CMD or angiographic spasm between groups. Further coronary endotype data is displayed in Table 1. Conclusion: Endothelial dependent and independent microvascular dysfunction are prevalent in patients presenting with known myocardial bridge and chest pain and rates are not affected by hemodynamic significance of the bridge. Knowledge of coronary endotype in patients with myocardial bridge may assist in tailoring therapies to improve chest pain.