Exploring the relationships between cardiac conditions and myocardial bridging in sudden cardiac death: a case control autopsy study

Background: Myocardial bridging (MB) is a congenital coronary anomaly characterized by a segment of coronary artery passing an intramuscular course through the myocardium. Traditionally considered a benign condition, MB has been associated with major cardiovascular events, such as angina, myocardial infarction, or even sudden cardiac death (SCD). Due to controversial evidence in existing literature, this study aimed to investigate the associations between MB and both gross and microscopic cardiac pathologies. We conducted a case–control autopsy study comparing individuals with and without MB who died of sudden cardiac death. Gross and histopathological cardiac findings were compared between groups. Univariate and multivariate logistic regression, correlation analyses, and subgroup comparisons were performed for statistical evaluation. Results: The prevalence of MB was 3.03% in total autopsies. Each group consisted of 172 cases. The mean length and depth of the myocardial bridging were 18.08 mm (SD: 13.08) and 2.64 mm (SD: 1.87 mm), respectively. Most of the cases had a short course (79.07%) and deeply embedded (63.95%) myocardial bridging. The association between heart weight and depth of segment was statistically significant (p = 0.001). When comparing the case and control groups for medical history and toxicological findings, no statistically significant differences were found. After multivariate analysis, we found that the case group had an increased odds ratio of 1.64-fold (95% Cl, 1.02–2.64, p = 0.042) in terms of left ventricular hypertrophy. Conclusions: MB shows potential associated with specific morphological and histopathological cardiac conditions; therefore, its contribution to sudden cardiac death should be evaluated carefully on a case-by-case basis. Future prospective longitudinal cohort studies are needed to clarify the impact of MB on sudden cardiac deaths and to evaluate its role as an independent etiologic risk factor in other cardiac conditions.