Question 20: The patient had atypical chest pain and the CTA was done to rule out a critical stenosis. What is the diagnosis?

Diagnosis: Myocardial Bridging

What is myocardial bridging?

• Definition: An epicardial segment of a coronary artery that courses through the myocardium is termed "myocardial bridging".
• It is a congenital anomaly
• Nonatherosclerotic anatomic abnormalities of the coronary arteries
• Muscle overlying a segment of coronary artery causes this appearance
• It was typically felt that this was not associated with clinical symptoms but now there is some concern that it is

Myocardial Bridging: Facts

• Congenital anomaly seen in 0.5-2.5% of angiographic studies
• LAD midsegment is most common zone involved
• Can result in symptoms beginning in the third decade
• Deep segment bridging is 2.3 mm or more myocardial coverage
• The artery that is surrounded by myocardium is called a tunneled artery
• The myocardial muscle covering the artery is termed the myocardial bridge
• May result in unstable angina, myocardial infarction, arrhythmia and death
• Usually considered a benign condition

Several other recent article make several other comments regarding the role of CTA as well as the potential importance of myocardial bridging

"MDCT is an effective noninvasive method for the diagnosis of myocardial bridging because MDCT can show the length and the depth of the tunneled artery and the diameter and percentage of stenosis in the segments showing myocardial bridging in the systolic and diastolic phases."

Myocardial Bridging on MDCT
Hazirolan T et al AJR 2007; 188:1074-1080

"Myocardial bridge predisposes to the development of atherosclerosis in the coronary artery segment proximal to the bridge. This may indicate that myocardial bridge should be considered an anatomic risk factor in the evaluation of CAD."

Myocardial Bridge: Evaluation on MDCT
Zeina AR et al.
AJR 2007; 188:1069-1073

"Myocardial bridges are commonly found in patients who undergo cardiac multidetector computed tomographic angiography on both single and dual source computed tomographic scanners and are most frequently located in the mid-left anterior descending coronary artery."

Myocardial Bridging: Evaluation Using Single and Dual Source Multidetector Cardiac Computed Tomographic Angiography
Jacobs JE et al.
J Comput Assist Tomogr 2008;32:242-246

"The prevalence of myocardial bridges was 10.4%, most of which were located in the mid-left anterior descending coronary artery. The average myocardial bridge length was 23.4 mm, and the average tunneled artery depth was 2.6 mm."

Myocardial Bridging: Evaluation Using Single and Dual Source Multidetector Cardiac Computed Tomographic Angiography

Jacobs JE et al.
J Comput Assist Tomogr 2008;32:242-246