415 DOES MYOCARDIAL BRIDGING TRIGGER MYOCARDIAL ISCHEMIA?

Background Myocardial bridging (MB) is a congenital epicardial coronary abnormality, in which a segment of the artery runs through the myocardium, determining dynamic stenosis during systole. Whether MB can be responsible by itself for myocardial ischemia remains unclear. Thus, we aimed to evaluate whether the dynamic stenosis related to MB can cause signs and symptoms of myocardial ischemia. Methods We enrolled 41 consecutive patients who underwent coronary angiography because of chest pain suspected for ischemic heart disease and were found to have MB in the absence of any significant flow-limiting coronary stenosis and any other cardiac disease. A group of 14 patients who also underwent coronary angiography because of chest pain suspected for ischemic heart disease, but found to be free of any coronary or cardiac abnormality (including MB) and also showed negative results at exercise stress test (EST) served as controls. All enrolled patients underwent a maximal treadmill EST according to standard Bruce protocol. A complete echocardiographic examination was performed at rest and at peak exercise. Results Baseline EST parameters were comparable between groups, whereas peak diastolic blood pressure (pDBP) was slightly higher in the MB group (p=0.044). No clinically significant differences were found in baseline echocardiographic parameters, although the E wave deceleration time (DcT) was longer (p=0.038) and global longitudinal strain (GLS) was higher (p=0.05) in the MB group. During exercise, left ventricular ejection fraction (LVEF) improved significantly in both groups (p Moreover, among MB patients, no differences were found in stress echocardiographic results between those with positive vs. those with negative EST. Conclusions We failed to demonstrate any significant ischemic impairment of LV systolic and diastolic function at maximal EST in patients with MB. Moreover, we also failed to demonstrate any LV dysfunction in MB patients that developed ECG signs of myocardial ischemia during EST, as compared to those without evidence of myocardial ischemia. Thus, our data question about the ability of MB itself to trigger significant myocardial ischemia in clinical practice.