Myocardial Bridging of the Left Anterior Descending Coronary Artery: Depiction Rate and Morphologic Features by Dual-Source CT Coronary Angiography

Objective: To evaluate the depiction rate and morphologic features of myocardial bridging (MB) of the left anterior descending coronary artery (LAD) using dual-source CT (DSCT). Materials and Methods: CT scans from a total of 1,353 patients who underwent DSCT were reviewed retrospectively for LAD-MB. Seventy-eight patients were excluded due to poor image quality or poor enhancement of the coronary artery. The length and depth of the MB were analyzed and classified as superficial or deep with respect to the depth (${\leq}$ 1 or < 1 mm) of the LAD tunneled segment. Superficial MB was subdivided into complete or incomplete types according to full or partial encasement of the myocardium. Results: Of the 1,275 patients included in this study, 557 cases of MB were found from 536 patients (42%). Superficial MB was observed in 368 of 557 (66%) cases, and deep MB was seen in 189 of 557 (34%) cases. Superficial MB showed 2 types: complete (128 of 368, 35%) and incomplete (240 of 368, 65%). The mean length of a tunneled segment for superficial MB was $16.4{\pm}8.6$ mm. The mean length and depth of a tunneled segment for deep MB were $27.6{\pm}12.8$ mm and $3.0{\pm}1.4$ mm, respectively. The incidence of atherosclerotic plaques in a 2-cm-long segment proximal to MB was 16%. Conclusion: The depiction rate of LAD-MB using DSCT in a large series of patients was 42%, with two-thirds of MB segments being the superficial type.