Myocardial bridging phenomenon is not invariable: A case report

Abstract

BACKGROUND

Myocardial bridging is a common anatomical malformation, and the milking effect is a characteristic phenomenon of myocardial bridging in coronary angiography. Generally, the phenomenon is invariable. However, this article reports an inconceivably rare myocardial bridging phenomenon that breaks through our conventional views. The milking effect changed obviously in two coronary angiography examinations, which subverted the traditional deep-rooted view of the myocardial bridging phenomenon and revealed the limitations of coronary angiography in diagnosing myocardial bridging and judging the prognosis of it.

CASE SUMMARY

A 63-year-old man was diagnosed with ST-segment elevation myocardial infarction and received primary percutaneous coronary intervention on December 26, 2019. His heart rate was 104 beats per minute, and blood pressure was 15.3/10.3 kPa. A severe milking effect was found in the left anterior descending coronary artery during his index coronary angiography on January 14, 2020. The patient was given intensive medical management, including a β1-adrenergic receptor blocker, during hospitalization and after discharge. Unexpectedly, coronary angiography showed that the previous impressive milking effect was dramatically alleviated (close to normal) at the follow-up on October 13, 2020. At that moment, the patient’s heart rate was 83 beats per minute, and blood pressure was 12.7/8.0 kPa.

CONCLUSION

The myocardial bridging phenomenon is not invariable and, in certain circumstances, may vary. Furthermore, the autonomic nervous system may be involved in the myocardial bridging phenomenon.

Keywords: Myocardial bridging; Milking effect; Autonomic nervous system; Endocrine system; Coronary angiography; Case report

Core Tip: Myocardial bridging is a common anatomical malformation. Coronary angiography is considered the routine method to diagnose myocardial bridging, and the milking effect is a characteristic phenomenon of myocardial bridging in coronary angiography. Myocardial bridging is generally classified as superficial or deep according to anatomical features, which can be manifested by the milking effect. While the milking effect is generally invariable, our case surprisingly showed that the milking effect is not invariable. In certain circumstances, the myocardial bridging phenomenon may vary, which can mislead us into judging the prognosis of myocardial bridging. Therefore, it is necessary to perceive myocardial bridging phenomenon anew.