STENT PROCEDURE COMPLICATED BY THROMBUS FORMATION DISTAL TO THE LESION WITHIN A MUSCLE BRIDGE

We report here a case of a patient who underwent percutaneous interven tion to the left anterior descending artery, complicated by thrombus f ormation within the myocardial bridge distal to the lesion, There was complete angiographic resolution of thrombus and restoration of the no rmal antegrade blood flow after infusion of glycoprotein IIb/IIIa anta gonist (abciximab). Our observation may suggest that the presence of m yocardial bridging distal to coronary lesions should be considered ser iously in preprocedural evaluation of the lesions as a potential risk factor for intracoronary thrombus formation. The main coronary arterie s and the proximal segments of their major branches lie free on the ep icardial surface of the heart. However, in some instances these vessel s may penetrate into the muscle being surrounded by the myocardium, wi th the overlying muscle referred to as a ''bridge''. Myocardial bridgi ng appears to be a congenital anomaly, due to failure of exteriorizati on of the primitive coronary intratrabecular arterial network. It occu rs in 5-86% of patients in autopsy studies [1-3], and it is observed a s systolic coronary artery narrowing in 0.5-12% of patients undergoing coronary arteriography [3]. Although the gross anatomist had long rec ognized that the epicardial coronary artery might on occasion course d irectly through a segment of cardiac muscle, the physiological signifi cance of this phenomenon was considered benign [4]. This is partly bec ause traditional teaching concerning coronary blood flow delivery to t he left ventricular myocardium emphasized the primacy of the diastolic phase of the cardiac cycle. However, myocardial bridging is not alway s a benign finding, with recent reports suggesting an association with myocardial ischemia, infarction, vasospasm, cardiac arrhythmias, and sudden death [3,5]. (C) 1998 Wiley-Liss, Inc.