Myocardial bridging and prognosis: more evidence but jury still out

Abstract

Myocardial bridging (MB) is a congenital variant of coronary anatomy in which a segment of a major epicardial coronary artery that normally has an epicardial course runs intramurally through the myocardium beneath the muscle bridge. It occurs most frequently in the mid-portion of the left anterior descending ( Figure 1 ). It is also called ‘tunneled artery’. Geiringer1 first presented an in-depth analysis of autopsy samples in 1951, but clinical interest and systematic research were triggered by observed association of MB with myocardial ischaemia. In this regard, although traditionally considered a benign condition, MB may cause clinical symptoms including angina, myocardial infarction, life-threatening arrhythmias, and sudden death.2–4 It is widely accepted that MB might cause these ischaemic complications5,6 either from direct compression of the coronary artery during systolic contraction or by enhancement of the natural progression of atherosclerosis in the coronary segment. Both mechanisms are closely associated with changes in haemodynamic stress driven by the force of the MB compression through a combination of anatomical properties, such as the location, length, and thickness of the MB.7 Figure 1 Example of myocardial bridging (MB) of the middle tract of left anterior descending (LAD) coronary artery as displayed on Cardiac CT ( A –3D volume rendering—arrowhead). The longitudinal curved multiplanar views in orthogonal planes ( B and C ) show the location and length of the MB. Axial cross-section of the LAD performed proximal ( D ), distal ( F ) and within the MB ( E ) show the typical pattern of deep intra-myocardial course. The deep or complete intra-myocardial course consists of a 360° myocardium surrounded vessel ( E —arrowhead) as also displayed in pathology sample ( E ′—arrowhead). The true prevalence of MB is not fully known because it is largely underdiagnosed by conventional angiography. cardiac computed tomography (CCT) …