Deep and long myocardial bridge.

A 67-year-old man presented with left-sided chest pain that occurred while he was sleeping. He had experienced similar symptoms once a month for the past three years but did not experience any chest pain during physical activity. Variant angina pectoris was suspected based on clinical manifestations, and an electrocardiogram-gated computed tomography coronary angiography (CTCA) was performed for excluding coronary artery stenosis. A three-dimensional (3D) reconstruction image of CTCA revealed the midportion of the left anterior descending artery (LAD) coursing within the myocardium. While the curved multiplanar reconstruction (MPR) at 75% of the R-R interval revealed patency of the segment during diastole, the curved MPR at 40% of the R-R interval revealed severe stenosis of the segment during systole. The patient was diagnosed as having deep and long myocardial bridge (MB) of the LAD. Generally, MB is considered a benign condition with a favorable long-term outcome. However, severe systolic stenosis and delayed diastolic relaxation of the tunneled artery can impair coronary blood flow, potentially leading to effort and variant angina, myocardial infarction, life-threatening arrhythmias, or sudden death. Although conventional coronary angiography was previously considered the gold standard for diagnosing MB, new imaging techniques such as intravascular ultrasonography, optical coherence tomography, and multi-detector CT are now available. CTCA can noninvasively show not only the morphological characteristics of MB but also the changes of MB from diastole to systole phase with a multiple-phase reconstruction technique using electrocardiogram-gated data acquisition.