Myocardial bridge of the left anterior descending coronary artery as a cause of acute coronary syndrome and ventricular tachycardia in a young patient. Case report

Myocardial bridges (MM) are common congenital anomaly of the coronary arteries (CA) with the location of a separate bundle of myocardial muscle fibers over any epicardial vessel, most often over the middle segment of the left anterior descending coronary artery (LAD). In most patients, MM has a benign course, though in 25% of cases, it can cause stable or unstable angina, myocardial infarction with non‑obstructive CA (MINOCA), paroxysmal rhythm disturbances, and sudden cardiac death. The pathophysiological mechanisms of the development of fatal and non‑fatal cardiovascular events in such patients are heterogeneous and usually complex. They may include mechanical obstruction of blood flow, violation of diastolic relaxation of the CA, local hemodynamic changes in the tunnelled segment, endothelial dysfunction, vasospasm, damage to the atherosclerotic plaque located in the MM zone, and spontaneous dissection of the CA. The purpose of our article was to present and discuss a clinical case of the development of MINOCA and potentially fatal ventricular arrhythmia in a 34‑year‑old man during competitive sports caused by MM in the LAD. MM was detected by invasive angiography. The diagnosis of MINOCA was established according to the criteria of the 4th universal definition of MI (clinical signs, ECG data, laboratory markers of myocardial damage). However, according to magnetic resonance imaging (MRI) of the heart 3 days after the onset of the disease, no inflammatory process, ischemic damage to the myocardium, and volume formations were found. At the same time, dilatation and hypertrophy of the left ventricle and myocardium fibrosis of non‑ischemic origin were present. There is currently no generally accepted algorithm for examining a patient with MM. Because of the heterogeneity of the pathophysiological mechanisms of myocardial ischemia in this cohort of patients, it is suggested to use invasive and non‑invasive angiography, invasive methods of intracoronary imaging, Doppler assessment of coronary blood flow, and provocative stress tests to detect vasospasm.