Evaluation of myocardial bridges with 64-slice computed tomography coronary angiography

Objective - The aim of this study is to report the characteristics of myocardial bridging (MB) using 64-slice computed tomography and to demonstrate the association between atherosclerotic coronary artery disease (CAD) and MB. Methods and results - In 990 consecutive patients who underwent multi-slice computed tomography (MSCT) coronary angiography for suspected or known coronary artery disease, myocardial bridge evaluation was performed with axial, curved multiplanar reconstruction and three-dimensional volume-rendered images. 265 bridged segments were identified in 223 (22.5%) patients. Multiple MBs on left coronary arteries were found in 41 patients. Most of the MBs were in the LAD (62.6%), followed by the obtuse marginal artery (14.7%) and diagonal artery (14.3%). The average length of MBs was 14 +/- 7 mm, and the average depth was 1.6 +/- 1.1 mm. No significant difference was observed between patients with and without MB on the middle LAD in respect of age, gender, prevalence of diabetes, hyperlipidaemia, hypertension, current smoking and prevalence of atherosclerotic plaques at the proximal LAD. On the other hand, prevalence of atherosclerotic plaques at the distal LAD were significantly lower in patients with MB on the middle LAD (3.5% vs. 19.7%, P: 0.0001). Conclusions - The presence and morphological characteristics of MB and its relation with atherosclerotic plaques in the involved coronary artery can be comprehensively analysed with 64-slice computed tomography coronary angiography. Atherosclerosis is a common finding in segments proximal to MB, but the prevalence of plaques in equivalent segments (proximal LAD in our study) is not higher than in patients under similar coronary artery disease risk and without MB. On the other hand, prevalence of atherosclerotic plaques at the distal LAD was significantly lower in our patients with MB on the middle LAD. Finally, we suggest that rather than causing proximal atherosclerosis, MB might have a more important role in the protection of distal segments of the bridged arteries from atherosclerosis.