Exploring the link between myocardial bridging and left ventricular hypertrophy: Congenital factors or remodelling?

Background: Myocardial bridging (MB) was considered a congenital anomaly and found increased frequency in coronary computed tomography angiography. Some case studies reported the association of MB with various cardiomyopathies. However, the association between MB severity and left ventricular hypertrophy remains unclear. This cross-sectional study aimed to evaluate whether myocardial bridge is related to left ventricular hypertrophy in patients referred for coronary computed tomography angiography (CCTA).

Methods: This cross-sectional study included two hundred and twenty-seven patients (age 53.2 [11.1] years, 48 % female) who underwent 640-slice CCTA and were diagnosed with MB. MB severity was measured as MB muscle index (MMI) (MB length x MB thickness) and, left ventricular hypertrophy (LVH) was assessed with transthoracic echocardiography.

Results: MB segments were detected in all patients on the left anterior descending artery. CCTA was performed to exclude coronary artery disease in most patients (90%, n=206). Eighty-two (36.1 %) had LVH, and MMI was significantly higher in patients with LVH than those without LVH (27.3[19.5-38.9] vs 24 [13.8-37.1], P = 0.022, respectively). There was a positive correlation between the left ventricular mass index and myocardial bridge length (r=0.414, P =0.001), MB index (r=0.310, P <0.001), and the age of the patients (r=0.191, P = 0.004). MB thickness and MMI were also positively correlated with relative wall thickness.

Conclusion: MB is a common finding, and its severity is associated with left ventricular hypertrophy in patients undergoing CCTA.