individuals without cardiac risk factors of atherosclerosis. The proposed mechanisms for these adverse cardiac events caused by MB presence including systolic compression, spasm, plaque and premature atherosclerosis development proximal and distal to the bridge and endothelial dysfunction [1, 3] . It has been postulated that the anatomic characteristics of MB such as site, depth length and volume index (MB depth multiplied by MB length) may be related to coronary ischemia and the occurrence of

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... dverse cardiac events even in patients exhibit no considerable coronary atherosclerosis. However, it is still not clear how the MB anatomical characteristics modulate the occurrence of adverse events or interfere with therapeutic strategies [4, 5] . Recently, a new emerging ECG markers, in particular Transmural A B S T R A C T Background: The clinical significance of coronary Myocardial Bridge (MB) anatomical characteristics is controversial in the literature. It is not clear whether MB has a benign or malignant clinical outcome. Objectives: To investigate the possible relationship between MB characteristics (depth, length and volume index) with ECG markers [T Peak-to-End interval (Tp-e), transmural dispersion of repolarization and Index of Cardiac Electrical Balance (iCEB)] and changes (ST-T and S/R ratio changes in V1 and aVL leads). Patients and Methods: Forty-one patients who were diagnosed as having MB at multi-detector CT exam were enrolled in the study. Results: MB depth and volume index were associated with notched QRS (p = 0.001 and 0.003 respectively) in the whole sample. The association of notched QRS with MB depth and volume index was more significant in patients with coronary atherosclerosis (p = 0.001 and 0.01 respectively). There was a statistically significant association between MB length (p = 0.006) and volume index (p = 0.001) with an increased S/R ratio in aVL lead in patients free from coronary atherosclerosis. No statistically significant association was observed between MB anatomical characteristics with ECG markers of increased arrhythmia (p > 0.01), including TDR, Tp-e and iCEB. Conclusion : MB depth and volume index showed a statistically significant association with notched QRS, particularly in patients with coronary atherosclerosis. H I G H L I G H T S • The clinical significance of coronary Myocardial Bridge (MB) anatomical characteristics is controversial in the literature. • It is not clear whether MB has benign or malignant clinical outcome. • The results of the present study showed that some MB anatomical characteristics are associated with significant ECG changes.