ABSTRACT
Objective To evaluate the relationship between concurrent myocardial bridge at anterior descending branch and the formation of coronary atherosclerosis plaques by using transluminal attenuation gradient (TAG). Methods A total of 198 patients underwent coronary CTA in Renji Hospital of Shanghai Jiaotong University School of Medcine from June 2017 to March 2018 and the results showed the anterior descending myocardial bridge. The data were retrospectively analyzed. All patients completed the coronary CTA with 320?row detector CT. According to the manifestations of myocardial bridge on CTA,the patients were divided into deep and superficial myocardial bridge groups. According to whether the patients were complicated with coronary atherosclerotic plaques, they were divided into isolated myocardial bridge group and myocardial bridge with coronary atherosclerotic plaque group. The thickness and length of myocardial bridge, the volume of coronary atherosclerotic plaques at the site of myocardial bridge, the pre?bridge and post?bridge TAG values, and the K ratio were recorded. Independent sample t test (normal distribution) or Mann?Whitney U test (skewed distribution) was used to compare the difference of measurement data among different groups. χ2 test was used to compare the difference of enumeration data among different groups. Pearson correlation test was used to analyze the correlation among pre?bridge and post?bridge TAG values,K ratio,thickness and length of myocardial bridge and plaque volume. The influence of above indexes on plaque occurrence was analyzed by binary logistic regression analysis. The relationship between main influence indexes and plaque formation was analyzed by receiver operating characteristic curve (ROC). Results Ninety nine patients had isolated myocardial bridge,99 with myocardial bridge and coronary atherosclerotic plaques,27 with superficial myocardial bridge and 171 with deep myocardial bridge. All atherosclerotic plaques occurred in pre?bridge and the mean volume of plaques was (91.6±83.0)mm3. The differences in sex, age, height, body weight and body mass index werenot statistically significant between isolated myocardial bridge group and myocardial bridge with coronary atherosclerotic plaque group (all P>0.05). The difference in pre?bridge TAG value was statistically significant between the isolated myocardial bridge group and myocardial bridge with coronary atherosclerotic plaque group (all P<0.05), but not statistically significant in post?bridge TAG value and K ratio (all P>0.05). The difference in pre?bridge and post?bridge TAG values and K value was not statistically significant between the superficial group and the deep group (all P>0.05). There was a weak negative correlation (r=-0.205,-0.316,-0.339,respectively,P<0.05) between the plaque volume and pre?bridge&post?bridge TAG values and K ratio. The pre?bridge TAG value significantly affected the plaque formation (P=0.014) and the odds ratio was 0.884 (95% CI 0.801 to 0.976). While other factors had no significant effects on plaque formation (all P>0.05). The area under curveof plaque formation promoted by pre?bridge TAG value was 0.582. When the diagnostic critical value was －37.26 HU/mm, the sensitivity and specificity of pre?bridge TAG value in plaque formation were 31.31% and 81.82%, respectively. Conclusion The TAG value of anterior descending bridge is an independent risk factor for plaque occurrence. The abnormal TAG value of anterior descending myocardial bridge can be detected early by CTA.
ABSTRACT
OBJECTIVE: To study the predictive value of transluminal attenuation gradient (TAG) derived from diastolic phase of coronary computed tomography angiography (CCTA) for identifying systolic compression of myocardial bridge (MB). MATERIALS AND METHODS: Consecutive patients diagnosed with MB based on CCTA findings and without obstructive coronary artery disease were retrospectively enrolled. In total, 143 patients with 144 MBs were included in the study. Patients were classified into three groups: without systolic compression, with systolic compression < 50%, and with systolic compression ≥ 50%. TAG was defined as the linear regression coefficient between intraluminal attenuation in Hounsfield units (HU) and length from the vessel ostium. Other indices such as the length and depth of the MB were also recorded. RESULTS: TAG was the lowest in MB patients with systolic compression ≥ 50% (−19.9 ± 8.7 HU/10 mm). Receiver operating characteristic curve analysis was performed to determine the optimal cutoff values for identifying systolic compression ≥ 50%. The result indicated an optimal cutoff value of TAG as −18.8 HU/10 mm (area under curve = 0.778, p < 0.001), which yielded higher sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy (54.1, 80.5, 72.8, and 75.0%, respectively). In addition, the TAG of MB with diastolic compression was significantly lower than the TAG of MB without diastolic compression (−21.4 ± 4.8 HU/10 mm vs. −12.7 ± 8 HU/10 mm, p < 0.001). CONCLUSION: TAG was a better predictor of MB with systolic compression ≥ 50%, compared to the length or depth of the MB. The TAG of MB with persistent diastolic compression was significantly lower than the TAG without diastolic compression.