The Influential Factors Of Proximal End’s Artery Atherosclerotic Stenosis With Coronary Myocardial Bridging

Objective Coronary artery and its main branches spread over the adipose tissue on the surface of epicardium, but sometimes one segment of them would sneak into the myocardium and covered by the myocardial fibers, and float to the surface of myocardium after extend a short distance. This myocardial bundle covering in the coronary is myocardial bridging (MB), and the covered coronary artery spreading over MB is called myocardial bridging-myocardial coronary artery (MB-MCA). Since MB-MCA are extruded in the contraction phase of each cardiac cycle, resulting the proximal end’s forward blood in contraction phase has the change of "vortex" pattern, thereby injuring the inner wall of the coronary artery, thus this place is easy to form atherosclerosis plaque, leads to the lumen stenosis of coronary artery, and this stenosis coronary artery would further leads to myocardial ischemia, clinically manifested as symptoms of angina, arrhythmias, and even sudden death, which seriously harm to the patients with MB-MCA. Therefore the special group of MB-MCA should be given more attention. However, the current research regarding to the impact of MB-MCA on patients, especially for the major risk factors of the occurrence of proximal end’s MB-MCA atherosclerosis stenosis at is less, but there is still no final conclusion. Based on CT coronary artery imagery technology, this study conducts retrospective research on stenosis and without stenosis coronary heart disease for the patients with MB-MCA, to investigate the potential risk factors of atherosclerosis of coronary artery for the patients with MB-MCA, and provide understanding and targeted prevention and treatment for this special group.Methods Conduct a retrospective analysis 387 MB patients diagnosed with MB were selected from 2156 patients in Qianfoshan Hospital Affiliated to Shandong University from Oct.2013 to Sep.2014 due to chest discomfort. Coronary artery CT and clinical data (smoking, high blood pressure, hyperlipemia, average heart rate, obesity index, muscular bridge pressure, ECG ischemia and length of muscular bridge). All patients are from Shandong Province, Han, unrelated. Patients take 0.5mg (1 tablet) nitroglycerin with sublingual in five minutes before checking, and fast more than four hours, the patient with greater than 60 beats/min heart rate should orally take 25mg (1 tablet) Metoprolol in one hour before checking. Thus it could reduce the artifact of heart beat and provide a clear image, and then observe the conditions of left coronary artery, right coronary artery and all branches. Subject to the most severe pathological changes, take use of the international universal visual diameter methods with Ⅰ-Ⅴ levels, Level Ⅰ (stenosis <25%), level Ⅱ (stenosis 25～ 50%), Level Ⅲ (stenosis 51～75%), Level Ⅳ (stenosis 16～90%), Level Ⅴ (stenosis> 90%), Level Ⅱ or above are defined as the atherosclerotic stenosis. At the same time conduct statistical analysis on the occurrence of proximal end’s coronary artery atherosclerotic stenosis through list, and calculate the incidence rate. It can be classified into two groups according to proximal end’s artery atherosclerotic stenosis: stenosis group with proximal end’s artery atherosclerotic (Ⅰ group) and stenosis group without proximal end’s artery atherosclerotic (Ⅱ group). Logistic regression model was used to analyze the relation between two groups and proximal end’s artery atherosclerotic stenosis of muscular bridge.Result Muscular bridge pressure from Ⅰ group was more serious than that of Ⅱ group. Logistic regression model shows that obesity (OR 2.852,95% CI 1.411～ 5.913), average heart rate (OR 2.852,95% CI 1.145～6.102), muscular bridge pressure (OR 3.366,95% CI 1.022～8.103) have positive correlation of proximal end’s artery atherosclerotic stenosis of muscular bridge when P<0.05. However, there is no statistical significance when P>0.05, smoking, high blood pressure, hyperlipemia, ECG ischemia and length of muscular bridge.Conclusion Obesity, average heart rate and muscular bridge pressure are related with proximal end’s artery atherosclerotic stenosis of muscular bridge.