Two cases of variant form angina pectoris associated with myocardial bridge--a possible relationship among coronary vasospasm, atherosclerosis and myocardial bridge.

Myocardial bridge (MB) is a congenital anomaly of the coronary artery and may occur in 5 to 12% of the human population. However, the mechanism of MB-induced myocardial ischemia is still speculative. We report 2 cases of variant form angina pectoris associated with MB in which myocardial ischemia seemed to be related to the interaction between coronary perfusion and MB. In case 1, electrocardiography during anginal attack at rest showed ST elevation in the inferior leads and MB was observed after percutaneous transluminal coronary angioplasty at the site of the right coronary artery lesion following successful dilatation. In case 2, MB of the left anterior descending coronary was located in the identical portion where coronary vasospasm was induced by intracoronary acetylcholine injection, although ischemia during the spontaneous anginal attack was limited to the inferior area of myocardium. These 2 cases suggest that MB can be, at least in some patients, one of the possible causes of the endothelial damage which seems to be related to coronary vasospasm; this was documented in both cases.