Abstract
Introduction: Myocardial bridge (MB) is a congenital anomaly in which a segment of a coronary artery is surrounded by myocardium. In our study, we want to use conventional coronary angiography (CCA) to describe morphologic characteristics of MB (unidentified or identified) in the patients with documented evidence of MB in coronary computed tomography angiography (CCTA). Methods: The present study was designed as cross-sectional and was conducted on 47 patients with documented evidence of MB in CCTA, who were referred to Nemazee and Faghihi hospitals for performing coronary angiography during a one year period. We compared the morphologic characteristics of tunneled segments, which were missed at CCA (unidentified), and the tunneled segments which were identified with CCA. Results: In sum, MB was found in 16 (34%) patients at CCA (identified), and it was not found in 31 (66%) patients (unidentified) based on compression sign. No significant correlation was found between the percentage of systolic compression and the length and depth of the tunneled segment in identified group (r=0.73, P = 0.18; r=1.09, P = 0.15; respectively). Degree of atherosclerotic plaque formation (diameter stenosis, percentage) (mean, 0.25 (25%) ±0.29; range, 0-0.98) of the tunneled segments in unidentified group was significantly more than the same degree (mean, 0.07 (7%) ±0.13; range, 0-0.41) of the identified group (P = 0.03). The measurement of the trapezoid area under the tunneled segment with this formula [(MB length+ intramyocardial segment) ×depth/2] had significant relation with systolic compression (r=0.304, P = 0.03) and defined the cut-off value of 250 mm2 as the value of significant difference in detecting myocardial bridging with CCA. Conclusion: Our results showed that in most of identified MBs in CCA the tunneled segment area was equal and more than 250 mm2. In addition, the degree of atherosclerotic plaque of the tunneled segments at CCA was significantly more in unidentified group.
Highlights
Myocardial bridge (MB) is a congenital anomaly in which a segment of a coronary artery is surrounded by myocardium
More than 50% of the tunneled segments were missed with conventional angiography, so they suggested that diagnosis of MB by visual estimation at conventional angiography can only be made for segments with more than 20% systolic compression.[5]
Materials and Methods We recruited 47 patients consecutively with documented evidence of MB in coronary CTA who referred to Nemazee and Faghihi hospitals, tertiary healthcare centers affiliated to Shiraz University of Medical Sciences (SUMS), for performing coronary angiography during 1-year period
Summary
Myocardial bridge (MB) is a congenital anomaly in which a segment of a coronary artery is surrounded by myocardium. Ferreira et al described two types of MB in left anterior descending (LAD) artery; superficial bridges that cross the artery vertically or at an acute angle toward the apex that comprise 75% of cases and deep bridges that are defined by muscle bundles arising from apical trabeculae of the right ventricle that cross the artery transversely, obliquely, or helically before inserting in the interventricular septum.[3] The MB prevalence varies widely according to the methods used to investigate such an anomaly In autopsy studies, it ranges from 15% to 85%1,4 while coronary angiography usually detects only 0.5%–12%. In the extent of our knowledge almost no specified study has been done on this field especially on characteristics of unidentified MB till
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