基于冠状动脉CT血管成像的血流储备分数评估心肌桥血流动力学变化的研究

The role of non-invasive fractional flow reserve derived from coronary CT angiography in assessing the hemodynamic relevance of myocardial bridging

目的探讨基于冠状动脉CT血管成像(CCTA)的血流储备分数(FFR)技术(FFRCT)评估心肌桥患者血流动力学改变的价值。方法回顾性搜集2016年1月至2017年4月中国人民解放军东部战区总医院行CCTA检查示左冠状动脉前降支心肌桥患者60例。根据心肌桥深度将其分为表浅组(30例)和纵深组(30例),另搜集同期30例年龄、性别相匹配的CCTA检查无明显异常患者作为对照组。测量心肌桥的位置、长度、深度以及收缩期管腔狭窄率,利用cFFR软件对所有患者的CCTA数据(包括收缩期和舒张期)进行三处(心肌桥入口前1~2cm、心肌桥中间段、心肌桥出口后1~2cm)FFRCT值测定。以任一期心肌桥远端FFRCT<0.75为界,将所有患者分为FFRCT正常组及FFRCT异常组。采用t检验或单因素方差分析比较组间年龄、心肌桥位置、长度、深度、收缩期狭窄率间的差异。采用非参数秩和检验对各组内两期FFRCT值以及不同分组间FFRCT值进行比较。采用logistic回归模型分析FFRCT异常与年龄、性别、心肌桥的位置、长度、深度、收缩期狭窄率间的关系。结果纵深组心肌桥段舒张期FFRCT值低于收缩期[分别为0.90(0.81,0.94)、0.93(0.91,0.97),Z=-2.172,P=0.03]。表浅组和纵深组心肌桥两期FFRCT值均低于对照组:收缩期对照组FFRCT为0.92(0.90~0.94),表浅组为0.84(0.77~0.88),纵深组为0.67(0.50~0.88),差异具有统计学意义(H=37.193,P<0.001);舒张期对照组FFRCT为0.93(0.89~0.94),表浅组为0.85(0.73~0.92),纵深组为0.81(0.65~0.87),差异具有统计学意义(H=26.508,P<0.001)。60例心肌桥患者中,28例FFRCT值异常(其中9例为表浅型,19例为纵深型)。心肌桥的长度(OR=1.067,95%CI:1.016~1.122,P=0.010)和深度(OR=2.028,95%CI:1.129~3.644,P=0.018)是造成FFRCT值降低(FFRCT<0.75)的危险因素。结论心肌桥中远端的冠状动脉FFRCT值降低;FFRCT值异常(FFRCT<0.75)更常见于纵深型心肌桥患者,心肌桥的长度和深度是造成FFRCT值降低的危险因素。

Objective To evaluate the role of non-invasive fractional flow reserve (FFR) derived from coronary CT angiography (CCTA) in assessing the hemodynamic relevance of myocardial bridging (MB). Methods A total of 60 patients without obstructive coronary artery disease but with CCTA-confirmed MB of the left anterior descending coronary artery and 30 patients with negative CCTA findings as control group were retrospectively included in this study. The 60 patients with MB were divided into 2 groups (superficial and deep MB group) according to the depth of MB. Age and sex were matched among three groups. The location, length, depth, and degree of systolic compression of the MB were measured. The FFRCT values(including systolic and diastolic phases) were measured at three points (segments 1 to 2 cm proximal to a MB, mid-tunneled segment and segments 1 to 2 cm distal to the MB) by cFFR software. Patients with FFRCT<0.75 were deemed to have hemodynamic relevance (abnormal group).χ^2 test, ANOVA test, Mann-Whitney U test, Kruskal-Wallis H test and logistic regression model were used for statistical analysis. Results The FFRCT values decreased from diastolic phase to systolic phase in deep MB group [0.90 (0.81-0.94) vs. 0.93 (0.91-0.97), Z=-2.172, P=0.03]. Compared to control group, the FFRCT values decreased in both diastolic phase and systolic phase in superficial MB group as well as deep MB group [systole 0.92 (0.90-0.94) control vs. 0.84 (0.77-0.88) superficial vs. 0.67 (0.50-0.88) deep, H=37.193, P<0.001;diastole 0.93 (0.89-0.94) control vs. 0.85 (0.73-0.92) superficial vs. 0.81 (0.65-0.87) deep, H=26.508, P<0.001]. Abnormal FFRCT values (<0.75) were found in 28 (47.7%) MB patients (9 superficial vs. 19 deep). The length (OR=1.067, 95% CI:1.016-1.122, P=0.010) and depth (OR=2.028, 95%CI:1.129-3.644, P=0.018) of MB were associated with the abnormal FFRCT values. Conclusions The FFRCT values of coronary artery distal to MB were lower than that without MB. Abnormal FFRCT values are more prevalent in deep MB. MB length and depth demonstrate moderate predictive value for an abnormal FFRCT value.