Clinical Analysis Of Myocardial Bridging With Atherosclerosis In Dual-Source CT Coronary Angiography

objectives:CT coronary angiography is widely used in clinical practice as a non-invasive technique for patients to evaluate the characteristics of myocardial bridging and atherosclerotic plaque.It is a retrospective and descriptive observation to study the distribution of myocardial bridge in specific populations,the anatomical features,the correlation between coronary atherosclerotic lesions and clinical epidemiological data.The effects of myocardial bridge on coronary atherosclerotic lesions were studied by comparing the data of patients without myocardial bridging.Methods:Patients suspected with coronary artery disease were examined by CT coronary angiography from January 2015 to December 2016 in Second Affiliated Hospital of Zhejiang University.The inclusion criteria defined as follows.? myocardial bridging(diagnosis by CTA;?hospitalized patients,clinical medical records complete.The exclusion criteria defined as follows.?clinical medical records incomplete;?poor image quality of CTA or the diagnosis does not conform to the requirements;? partial encasement.Coronary CT data were harvested,including the distributions of myocardial bridging and atherosclerotic plaque,the depth and length of myocardial bridging,the compression degree of mural coronary artery involved and stenosis degree,as well as the clinical characters,such as age,sex,disease and medical treatments.The correlations of clinical risk factors with the incidence and distribution of myocardial bridging were analyzed.The distributions and stenosis degree of atherosclerotic plaque were analyzed in patients with or without myocardial bridging.Furthermore,the incidence and stenosis degree of atherosclerotic plaques located to the proximal of myocardial bridging were studied in between the difference of age and sex.The distribution of plaque in the two groups was compared with that of the control group,which was matched with coronary artery CTA at the same time and matched with gender,age,smoking,hypertension,diabetes mellitus and hyperlipidemia.SPSS 20.0 was used for statistical analysis.? enumeration data were expressed as the number of cases(composition ratio).The differences between the two groups were analyzed using chi-square test or Fisher's exact test.?)All measurement data was analyzed for normal distribution,variance analysis and nonparametric test.Mean ± standard deviation was expressed as the data for normal distribution,using Student t-test and Pearson test for the correlation between two variables.Median(p25,p75)was expressed as the data for non-normal distribution,using Mann-Whitney test and Spearman test for the correlation between two variables.Logistic regression was analyzed for the relationship between the risk factors and atherosclerotic plaque located at the proximal of myocardial bridge.Results:Five hundred and four patients with myocardial bridging were enrolled in this study,with the average age of 64.4 ± 11.1(range from 29 to 90 years old),307 male(60.9%)and 197 female(39.1%).Five hundred and forty myocardial bridging were found,88.89%of them located at left anterior descending(LAD),81.88%of them located at the middle LAD,and 3.7%of them located at left circumflex artery(LCX).Multiple myocardial bridging were found in 29 patients(5.75%).It's more common for two myocardial bridgings located at LAD simultaneously,the less for LAD and diagonal branch.Four myocardial bridgings were only found in one patient.The average depth was 3.53 ± 1.90mm,while the average length was 22.70 ± 8.48mm.The length of myocardial bridging was longer in male than female(P<0.05).There was no significant correlation of compression degree in diastolic phase with the depth,length or index of myocardial bridging.There was significance in age,history of hypertension,diabetes,hyperlipidemia,peripheral artery disease,and renal insufficiency between those with myocardial bridging alone and those accompanied with atherosclerosis(P<0.05).The prevalence of atherosclerotic plaque is higher in proximal part than distal part of myocardial bridging.There was significance in age,the incidence of hypertension,diabetes,hyperlipidemia,peripheral artery disease,renal insufficiency,cardiac insufficiency,and treatment between those with myocardial bridging alone and those accompanied with proximal atherosclerotic plaque.By analyzing the subgroups,we can see that,the prevalence of proximal plaque and the degree of stenosis is increasing with age.Multivariate analysis revealed that age,hypertension,diabetes,hyperlipidemia were the risk factors for coronary atherosclerosis in myocardial bridging patients(OR=1.06,1.93,2.09,1.78).Age,hypertension,hyperlipidemia were the risk factors affecting the formation of proximal plaque(OR= 1.06,1.89,2.43).There were 223 patients without myocardial bridging in control group,the average age was 66.4 ± 11.2 years,133 males(59.6%).Compare to the group without myocardial bridging,myocardial bridging group had less atherosclerotic plaque in mid LAD.But there's no difference in proximal part.The presence of mid-LAD myocardial bridging have no obvious effect on the degree of stenosis.Conclusions:MB were frequently localized in the mid segment of the LAD,and more commonly seen in male than female.Age,hypertension,hyperlipidemia were the risk factors affecting the formation of atherosclerotic plaque in proximal part.The presence of the mid LAD myocardial bridging does not affect the distribution and stenosis of the proximal atherosclerotic plaque,which is related to the decrease of plaque distribution in the middle of the LAD.