Quantitative evaluation of the myocardial bridge anatomical features and FFRCT in patients with myocardial bridging stratified by age

Myocardial bridge (MB) is a congenital coronary artery anomaly associated with various cardiac events. This study aimed to evaluate the effect of age on the anatomical features and computed tomography-derived fractional flow reserve (FFRCT) of the left anterior descending coronary artery (LAD) MB by using coronary computed tomography angiography. A retrospective study of 139 patients with LAD MB was conducted by dividing patients into 2 groups based on MB length: the short MB group (<20 mm, n = 58) and the long MB group (≥20 mm, n = 81). Patients were further categorized into 3 age groups: young (<45 years, n = 28), middle-aged (45-59 years, n = 89), and elderly (≥60 years, n = 22) groups. Coronary computed tomography angiography was used to measure the anatomical features of the MB. FFRCT values were calculated using a deep learning software at 3 locations along the LAD in the systolic and diastolic phases. Statistical analyses were performed using SPSS 21.0. In the long MB group, the FFRCT values were lower than those in the short MB group; moreover, the △FFR in the long MB group was larger than that in the short MB group (P < .05). No significant differences were found in clinical data, MB anatomical features, or FFRCT values among the age groups. In the middle-aged group, patients with abnormal FFRCT values had a significantly longer MB, closer MB location, and higher muscle index than those with normal FFRCT values (P < .05). In the elderly group, only MB length was significantly longer in patients with abnormal FFRCT values (P < .05). The youth group showed no significant difference between the normal and abnormal FFRCT groups. While age did not significantly affect MB anatomy and FFRCT values overall, specific MB anatomical parameters may contribute to decreased FFRCT values in middle-aged and older patients, providing valuable insights for MB hemodynamic assessment.