High Prevalence of Coronary Arterial Plaque Formation in Segments Proximal to the Myocardial Bridge: An MDCT Study

Myocardial bridge (MB), a congenital variant with narrowing of the coronary artery, resulting from overlying myocardium depicted in the systolic phase, is often identified at the middle portion of the left anterior descending artery. From August 2007 to October 2008, 694 patients were subjected to coronary artery examination using 64-MDCT (64 Multi-detector row Computed Tomography). Patients with documentated coronary artery disease or main risk factors such as old age (＞60 y/o), hypertension, high blood cholesterol level, diabetes, smokers and congenital anomalies were excluded from the study. Only cases with superficial myocardial bridge at mid-LAD (the middle segment of left anterior descending coronary artery) were enrolled. The survey thus involved 137 patients, who were divided into two groups: patients with mid-LAD superficial myocardial bridge and without stenosis at the distal segment of LAD (n=48), and normal anatomic coronary artery, which was considered as the control group (n=89). The incidence of plaque formation at the LAD in both groups was evaluated. The statistical probability of plaque formation was higher in patients with mid-LAD superficial myocardial bridge (52%) than in the control group (31%) (p＜0.05). Mild luminal stenosis in systolic phase was usually noted in the case with mid-LAD superficial myocardial bridge, possibly raising the incidence of plaque formation. Therefore, myocardial bridge may be a potential anatomic risk factor of coronary artery disease.