Impact of Myocardial Bridge-mural Coronary Artery on Myocardial Functions.

Objective To study the impact of myocardial bridge (MB)-mural coronary artery (MCA) on myocardial functions.Methods Totally 82 patients presenting with chest tightness and chest pain who were diagnosed with the MB in the left anterior descending artery by CT coronary angiography were enrolled as the MB group,in which the thickness and length of MB and the systolic stenosis degree of MCA were measured.In addition,82 healthy subjects,as confirmed by health check-up,were set as the control group.The age,gender,body mass index (BMI),heart rate (HR),smoking history,interventricular septal thickness,left ventricular posterior wall thickness,diameter of left atrium,left ventricular end-diastolic diameter,left ventricular end-systolic diameter,left ventricular ejection fraction,and the cases of E'/A'<1 were compared between MB group and control group.The potential correlations among the thicken/length of MB,the systolic stenosis degree of MCA and early diastolic peak strain rate(SRe)/late diastolic peak strain rate(SRa) were analyzed.Results The age (t=0.97,P=0.65),gender (χ2=0.10,P=0.75),BMI (t=1.82,P=0.07),HR (t=0.87,P=0.39) and smoking history (χ2=0.43,P=0.51) were not significantly difference between these two group.The interventricular septal thickness (t=1.54,P=0.13),left ventricular posterior wall thickness (t=1.47,P=0.14),diameter of left atrium (t=1.62,P=0.11),left ventricular end-diastolic diameter (t=0.49,P=0.63),left ventricular end-systolic diameter (t=1.29,P=0.20),and left ventricular ejection fraction (t=0.56,P=0.57) were also not significantly different between the normal and MB group.However,there was significant difference in the cases of E'/A'<1 (χ2=38.22,P=0.00).The SRe (r=-0.97,P=0.00;r=-0.93,P=0.00)and SRa (r=-0.89,P=0.00;r=-0.90,P=0.00) the left ventricular anterior wall were negatively correlated with the thickness of MB and the systolic stenosis degree of MCA and were not correlated with the length of MB (r=-0.09,P=0.76;r=-0.13,P=0.66).Conclusions MB is not correlated with myocardial systolic function,but can affect myocardial diastolic function.When the MB thickness increases,the systolic stenosis degree of MCA increases,the myocardial diastolic function gradually decreases,but the MB length is not related to myocardial systolic function.