Isolated myocardial bridge – not so benign?

Isolated myocardial bridge – 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 [1] 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 with coronary vasospasm. They suggested intensive medical therapy which should include antiplatelet agents 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 [2]. Unroofing of myocardial bridge is an option considered in cases with refractory symptoms.

References

1. Sung-Soo Kim, Myung Ho Jeong, Hyun Kuk Kim, Min Chul Kim, Kyung Hun Cho, Min Goo Lee, Jum Suk Ko, Keun Ho Park, Doo Sun Sim, Nam Sik Yoon, Hyun Ju Yoon, Hyung Wook Park, Ju Han Kim, Young Joon Hong, Young Keun Ahn, Jeong Gwan Cho, Jong Chun Park, Jung Chaee Kang. Long-term clinical course of patients with isolated myocardial bridge. Circ J. 2010 Mar;74(3):538-43.
2. Yukio Ishikawa, Yoshikiyo Akasaka, Koyu Suzuki, Mieko Fujiwara, Takafumi Ogawa, Kazuto Yamazaki, Hitoshi Niino, Michio Tanaka, Kentaro Ogata, Shojiroh Morinaga, Yoshiro Ebihara, Yutaka Kawahara, Hitoshi Sugiura, Toshiro Takimoto, Akio Komatsu, Toshihito Shinagawa, Kazuhiro Taki, Hideaki Satoh, Kazuaki Yamada, Maki Yanagida-Iida, Reiko Shimokawa, Kazuyuki Shimada, Chiaki Nishimura, Kinji Ito, Toshiharu Ishii. Anatomic properties of myocardial bridge predisposing to myocardial infarction. Circulation. 2009 Aug 4;120(5):376-83.