| The myocardial bridge(MB)is a common anatomical variant of the coronary artery.When the coronary artery under the epicardium enters the myocardial tissue at various lengths and then re-enters the epicardium,the myocardial tissue covering the surface of the section of coronary artery is called the myocardial bridge and the coronary artery below the myocardial bridge is called the mural coronary artery(MCA).Studies have shown that this particular anatomy is closely associated with myocardial ischemia,arrhythmias,atrioventricular block and even sudden death in patients.The detection and assessment of myocardial bridges is a prerequisite for their precise treatment and good prognosis.Recent developments in coronary-related medical imaging and advances in functional assessment tools have provided new options for the detection and assessment of myocardial bridges.Therefore,this study aims to improve the scientific detection of myocardial bridges and the accuracy of myocardial ischemia assessment by comparing the detection of myocardial bridges by coronary CT angiography(CCTA)and coronary angiography(CAG),and to investigate the value of the new quantitative flow ratio(QFR and D-QFR)in evaluating the hemodynamic changes of myocardial bridges,and to provide an important reference for the choice of myocardial bridge treatment.This study retrospectively collected 473 patients who underwent both CCTA and CAG at our center from June 2012 to June 2022.Comparison of the differences in myocardial bridge detection and morphological parameters between the two examination modalities.Among patients with myocardial bridges detected by CCTA,patients were divided into CAG-detected and non-detected groups according to whether myocardial bridges were detected by CAG,and relevant indicators were compared between the groups and the factors affecting the detection of myocardial bridges by CAG were analysed.Comparison of CAG for detection of myocardial bridges in patients with or without CCTA for combined proximal plaques and analysis of risk factors associated with proximal plaque formation in myocardial bridges.In the same period,83 patients with CAG showing simple myocardial bridge in the anterior descending branch were selected for the study,and they were divided into group A(stenosis<50%)and group B(stenosis≥50%)according to their systolic stenosis rate.QFR values were measured at three locations[1 to 2 cm before the MCA entrance(location a),the middle segment of the MCA(location b),and 1 to 2 cm after the MCA exit(location c)]in both phases(systolic and diastolic)of the MCA using the QFR prototype software,and deformation quantitative flow ratio(D-QFR)values were measured.With a cut-off value of QFR≤0.8 at the distal end of the MCA at either stage,patients with myocardial bridges were divided into a normal QFR group(QFR>0.8)and an abnormal QFR group(QFR≤0.8).The QFR values were compared and analysed between groups A and B and within each group;logistic regression was used to analyse the factors influencing abnormal QFR values;the correlation between systolic and diastolic QFR values and D-QFR values was analysed.Multiple linear regression was used to perform a multifactorial analysis of the D-QFR values.The results of this study showed:In the comparison of detection in patients with myocardial bridges and types of myocardial bridges respectively,it was found that the detection rate of CCTA was significantly higher than that of CAG in patients with myocardial bridges and superficial myocardial bridges(P<0.001),while there was no statistical difference between the two groups in the detection rate of deep myocardial bridges(P>0.05);the length of myocardial bridges in CCTA was longer than in CAG in both superficial and deep myocardial bridges(both P<0.05),while the systolic stenosis rate was lower than in CAG(both P<0.001).The depth of myocardial bridges and the rate of systolic stenosis were higher in the CAG-detected group than in the CAG-undetected group(both P<0.05),whereas the degree of proximal fixed stenosis was lower than in the CAG-undetected group(P=0.01),and the depth of myocardial bridges(OR=1.891,95%CI:1.068-3.349,P=0.029)was a factor facilitating the detection of myocardial bridges by CAG,while proximal fixed stenosis(OR=0.982,95%CI:0.969-0.996,P=0.011)was a hindrance to detection;the detection of myocardial bridges by CAG was lower in myocardial bridges combined with proximal plaques than in patients without combined proximal plaques(37.97%vs76.19%),with a difference statistically significant(P=0.002);HDL cholesterol(OR=0.063,95%CI:0.005-0.809,P=0.034)was a relevant factor in inhibiting atherosclerosis.The results of this study also showed that there was no statistically significant difference in QFR values between group A and group B at position a(P>0.05),while the differences in systolic and diastolic QFR values at position b and position c were statistically significant(both P<0.01);Within-group comparisons revealed no statistically significant differences between the two-phase QFR values at position a in groups A and B(both P>0.05),while the differences between the two-phase QFR values at positions b and c were statistically significant(both P<0.01).The intra-group comparison of QFR values at different locations during the same period showed that the differences among QFR values at different locations were statistically significant(P<0.05),except for no statistically significant differences between QFR values at diastolic locations b and c in group A.The systolic stenosis(OR=1.22,95%CI:1.09-1.36,P<0.001)was an independent influence on abnormal QFR values,with an area under the curve(AUC)of 0.923(95%CI:0.868-0.978,P<0.001)predicting abnormal QFR values and an optimal cut-off value of 50.25%;there was a significant positive correlation between D-QFR values and both systolic and diastolic QFR values(r_s=0.849,r_s=0.675,both P<0.01).Multiple linear regression analysis showed that D-QFR values were negatively correlated with age,systolic stenosis and myocardial bridge length(b=-0.001,b=-0.002,b=-0.002,all P<0.05).The above results show that CCTA has a significant advantage over CAG in the detection of myocardial bridges,especially in cases of combined proximal plaques,and that CCTA also has a high ability to identify the length and depth of myocardial bridges,therefore,it is important to improve the application of CCTA in the scientific detection of myocardial bridges for the subsequent diagnosis and treatment of myocardial bridges.The new quantitative flow ratio has good feasibility in the assessment of myocardial bridge hemodynamic changes,and the QFR value can be used as an objective evaluation index of myocardial ischemia associated with myocardial bridges;The D-QFR technique,developed in-house for the hemodynamic characteristics of myocardial bridges,incorporating deformation analysis,is expected to be an important tool for the assessment of myocardial ischemia associated with myocardial bridges. |
PDF Full Text Request