Isolated myocardial bridge on coronary angiography – not so benign?

Isolated myocardial bridges seen on coronary angiography are generally considered as benign. Myocardial bridge is the situation in which a portion of the epicardial coronary artery passes beneath a myocardial bridge so that it is seen as a narrowing of the coronary artery in systole, but not in diastole. Kim SS and associates [Long-term clinical course of patients with isolated myocardial bridge. Circ J. 2010;74:538-43] from the Department of Internal Medicine, Chonnam National University Hospital, Gwangju, Republic of Korea, investigated whether these are really benign findings by a study with mean follow up of over three years. They found there was a significantly higher incidence of readmission with chest pain in those with myocardial bridges. It may even cause myocardial infarction or life threatening arrhythmia, though the incidence is low. The risk was higher in those with long myocardial bridge and associated coronary vasospasm. They suggested intensive medical therapy which should include anti platelet agent aspirin and statin which were shown to decrease the readmission rate.
Ishikawa Y et al found that the myocardial bridge muscle index (myocardial bridge thickness multiplied by the length of the myocardial bridge) if higher, tended to shift coronary artery disease in the left anterior descending coronary artery more proximally, thereby having a potential to increase the risk of myocardial infarction [Anatomic properties of myocardial bridge predisposing to myocardial infarction.
Circulation. 2009;120:376-83].

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