Abstract 4368794: Plaque and Coronary Artery Characteristics in Patients With Myocardial Bridging With and Without Hypertrophic Cardiomyopathy: A Propensity-Matched Analysis

Background: Myocardial bridging (MB) occurs when an epicardial coronary artery traverses into the myocardium. There are limited data comparing plaque characteristics of patients who have left anterior descending artery (LAD) MB and hypertrophic cardiomyopathy (HCM) with those who have a normal left ventricular phenotype and no HCM utilizing coronary computed tomography angiography (CCTA). Aims: To explore the differences between patients with and without HCM who have MB on CCTA. Methods: We retrospectively analyzed all adult patients with HCM at our specialized HCM center from January 2014 to January 2025 who had an available CCTA. Patients who had a percutaneous coronary intervention or coronary artery bypass graft surgery before the CCTA were excluded. The cohort was then propensity-score matched to a control group of individuals who did not have HCM and had an available CCTA. Only patients with LAD MB on CCTA were included. Results: A total of 244 patients with HCM were identified and propensity-score matched 1 to 1 with non-HCM patients. There were 68 HCM patients (28%) with MB and 18 non-HCM patients (7%) with MB who were the subjects of this study. The HCM-MB group had a mean age of 51 ± 15 years (37% female), and the non-HCM-MB group had a mean age of 55 ± 15 years (39% female). In the HCM-MB group, the HCM phenotypes observed were basal septal (54%), reverse curvature (24%), apical (13%), midventricular (6%), and concentric (3%). Sixty-two patients had genetic testing: 29 patients (47%) were likely pathogenic, 19 patients (31%) had a variance of uncertain significance, and 14 patients (23%) were gene-negative. The average coronary artery calcium score in the HCM-MB group was 79 Agatston units, which is comparable to the average score of 101 Agatston units in the non-HCM-MB group (P=0.32). In the HCM-MB group, 39 patients (57.3%) were diagnosed with CAD compared to 13 patients (72%) in the non-HCM-MB group (P=0.41). There were no statistically significant differences in plaque prevalence or characteristics between the two cohorts for any of the coronary artery vessels (Table 1). Conclusions: Myocardial bridging was more common in patients with HCM, yet these patients had lower coronary artery calcium scores and fewer CAD diagnoses.