Clinical Analysis Of Coronary Myocardial Bridge

Background:Myocardial bridge (MB) is a kind of congenital abnormal development of coronary artery. Muscle overlying the intramyocardial segment of an epicardial coronary artery is termed a myocardial bridge (MB). The artery coursing within the myocardium is called a tunneled artery. The present study was aimed to evaluate the incidence and clinical manifestation of MB by analyzing the angiographic results from 1862 patients. The impact of MB on the immediate and mid-term outcomes of primary percutaneous coronary intervention (PCI) was also evaluated in the present study.Methods:Out of 1862 patients who underwent coronary angiography in Tianjin NanKai Hospital from Nov 2006 to Feb 2010, a total of 356 patients were diagnosed with MB. Grouping:1.Patients with left anterior descending (LAD) MB were divided into two groups:Group A:systolic compression<50%(n=176); Group B:systolic compression=50%(n=168).2.Patients with LAD MB who didn't have coronary artery disease (CAD) were divided into two group:Group Al:systolic compression <50%(n=71); Group B1:systolic compression=50%(n=86).3.Patients with AMI who underwent primary PCI were divided into two groups:MB group (n=11) and non-MB group (n=224). Clinical and angiographic characteristics were recorded.Patients with AMI who underwent primary PCI received regular clinical follow-up up to 6 months. All analysis were performed using SPSS 13.0 software and the statistically significant exists if P<0.05.Results:1.The prevalence of myocardial bridge is 19.12% mainly seen in LAD accounting for 96.91%. And 81.68% MB were located in the mid segment of LAD. MB were more commonly seen in male patients than female patients (P=0.001). 2.The incidences of angina, AMI, heart failure, atrial fibrillation and atrial tachycardia were significantly higher in Group B as compared with Group A (P<0.01).3.The age, sex, hypertension, hyperlipidemia, family history of CAD, and smoking habit did not differ significantly between Group A and Group B, Group A1 and Group B1, while the incidence of diabetes was higher in Group A as compared with Group B (P=0.012), the incidence of diabetes was still higher in Group Al as compared with Group B1 (P=0.049), the incidence of CAD was higher in Group B as compared with Group A (P=0.043).4. The incidence of atherosclerosis was significantly higher at the proximal part as compared with the distal part of MB(P=0.000).The incidence of atherosclerosis at the proximal part was significantly higher in Group B as compared with Group A (P<0.001).5.The diameter of tunneled artery was decreased after intracoronary injection of nitroglycerin (P=0.000),the diameter of proximal reference and the systolic compression were increased after intracoronary injection of nitroglycerin (P=0.000).The length of MB was not significantly different after the injection.6.In AMI patients who underwent primary PCI, the rate of immediate TIMIâ…¢blood flow was significantly higher in Non-MB group as compared with MB group (P=0.01). While the inhospital mortality did not differ significantly. LVEF (%) at 6 months were significantly higher in non-MB group as compared with MB group (P=0.001). Furthermore the incidence of 6-month MACE was significantly higher in MB group as compared with Non-MB group (P=0.006).Conclusions:1.The prevalence of MB is 19.12%. MB is most commonly seen at the mid part of LAD and in male patients.2.The severity of MB is significantly and positively correlated with the incidences of angina, AMI, heart failure, atrial fibrillation and atrial tachycardia.3.The incidence of diabetes was significantly higher in groups representing <50% of systolic compression, which indicates the diabetes has the corrolation with the compression of the myocardial bridge.4.The proximal part of MB has higher chance to develop atherosclerosis as compared with distal part and MB part. More severe compression of MB usually causes higher incidence of atherosclerosis at the proximal part of MB.5.Nitroglycerin can increase the systolic compression of MB and improve the detection rate.lt prompts Nitroglycerin doesn't apply medical treatmen for MB.6.AMI patients with MB have worse post-PCI blood flow and higher incidences of 6-month major adverse cardiac events as compared with those without MB, suggesting MB is an adverse impact factor for the immediate and mid-term clinical outcomes of patients with AMI.