Myocardial bridging phenomenon is not invariable: A case report

Table 1 Timeline summarizing the patient’s information, clinical findings, diagnosis, treatment, and follow-up

Timeline
Patient’s information	A 63-year-old man presented with persistent chest pain that had lasted for 1 d on December 26, 2019. His heart rate was 104 beats per minute, and blood pressure was 15.3/10.3 kPa
Clinical findings	The level of cardiac troponin T was high (0.597 ng/mL; normal range: 0.000-0.014 ng/mL), as was that of myoglobin (246.80 ng/mL; normal range: 28.00-72.00 ng/mL) and Pro-BNP (6828.00 pg/mL; normal level: < 161 pg/mL). Tests of HRV and norms showed the HRV indices SDNN to be 19 ms. Myocardial bridging was stenosed about 90% during systole and recovered during diastole on January 14, 2020
Diagnosis	The patient was mainly diagnosed with ST-segment elevation myocardial infarction, and his cardiac function was assessed as Killip class Ⅲ
Treatment	The patient accepted PCI and one drug eluting stent was implanted. After PCI, the patient was instructed to take a low-salt, low-fat and diabetic diet and avoid exertion and rage. He was also instructed to take drugs for secondary prevention of coronary heart disease (administered orally as 5 mg qd of bisoprolol fumarate, 0.1 g qd of aspirin, 75 mg qd of clopidogrel, 10 mg qd of rivaroxaban, and 10 mg qn of rosuvastatin calcium) and to manage blood glucose (administered orally as 50 mg qd of acarbose and 100 mg qd of sitagliptin phosphate, and administered as subcutaneous injections with 4 IU to 6 IU of insulin aspart before meals and 12 IU of insulin glargine before sleep)
Follow-up	On October 13, 2020, the follow-up manifested that the previous MBP changed dramatically with a stenosis decrease from 90% to 30% during heart systole. In this follow-up, the patient’s heart rate was 83 beats per minute and blood pressure was 12.7/8.0 kPa. The level of cardiac troponin T lowered substantially (0.034 ng/mL) and that of myoglobin normalized (32.53 ng/mL). Pro-BNP also lowered substantially (321.30 pg/mL)

Pro-BNP: Pro-B-type natriuretic peptide; HRV: Heart rate variability; SDNN: Standard deviation of RR-intervals; PCI: Primary percutaneous coronary intervention; MBP: Myocardial bridging phenomenon.