Myocardial Bridging in Cases of Sudden Death and its Association with Clinicopathologic Characteristics

Myocardial bridging (MB) is the course of the epicardial segment of a coronary artery within the myocardium. The systolic compression of this segment called the tunneled segment may lead to alterations in blood flow to the heart. We have studied the gross and microscopic features of MB in cases of sudden cardiac death and analyzed its characteristics and whether there is any association with other clinicopathological characteristics which may help us to understand the pathogenesis and risk stratification.

This is a retrospective descriptive study of 132 postmortem heart specimens of sudden cardiac death. The coronary arteries were dissected, and MB and its characteristics were studied. Statistical analysis was performed using the Chi-square and Fisher's exact tests (P < 0.05 significant).

MB was present in 28 cases (21.2%), with a mean age of 49.5 years and male:female ratio of 27:1. MB was seen in the left anterior descending artery in 86.2% of cases, the right coronary artery in 10%, and left circumflex artery in 3.5% of cases. Atherosclerosis was seen in the segment proximal to the tunneling in 89.2% of cases leading to infarction in four cases. Left ventricular hypertrophy (LVH) was significantly associated with MB cases (19/68%) (P < 0.05).

MB causes turbulence of blood in the proximal segment leading to coronary atherosclerosis, thereby predisposing the heart to ischemic changes and LVH and may lead to infarction in a few cases.