Myocardial bridging, a frequent component of the hypertrophic cardiomyopathy phenotype, lacks systematic association with sudden cardiac death

The clinical significance attributable to myocardial bridging of left anterior descending coronary artery in hypertrophic cardiomyopathy (HCM) remains controversial. Prevalence and depth of coronary artery bridges (CBs) were assessed in 255 hearts, including 115 with HCM (median age 29, range 5–90; 75% male), and 140 controls. Coronary artery bridges were more common in HCM (47/115; 41%) than in patients who died of a variety of non-HCM-related causes (21/100; 21%; P = 0.002), or in patients with congenital aortic stenosis and left ventricular (LV) hypertrophy (5/40; 12%; P = 0.001). Among the HCM hearts, CBs were present in 33 of 77 patients (43%) with sudden death, in 10 of 27 (37%) with heart failure death (or heart transplantation), and in 4 of 11 (36%) with other modes of death (P = 0.826). Deeply embedded CBs (≥2 mm) occurred with similar frequency in HCM patients with sudden (21 of 77; 27%) or heart failure death (5 of 27; 13%; P = 0.191). In sudden death patients, the presence of CB was unrelated to gender (33% in women and 45% in men, P = 0.406) and age (41% <18 years vs. 44% ≥18 years; P = 0.827). In this morphological analysis of more than 250 hearts, CBs are a frequent component of phenotypically expressed HCM, and more common than in other disorders with or without LV hypertrophy. Although no systematic association with HCM-related sudden death is evident, our findings do not exclude the possibility that CB could contribute to increased risk in some individual patients, potentially impacting management decision-making on a case-by-case basis.