左前降支心肌桥对其近端冠状动脉周围脂肪衰减指数的影响分析

Analysis of the Effect of Left Anterior Descending Myocardial Bridging on the Pericoronary Fat Attenuation Index

摘要: 目的：本研究旨在探讨左前降支(LAD)心肌桥–壁冠状动脉复合体(MB-MCA)的存在及其解剖学特征，特别是心肌桥(MB)厚度，对其近端冠状动脉周围脂肪衰减指数(FAI)的影响，以阐明心肌桥对血管周围炎症状态的潜在作用。方法：采用一项双中心、回顾性队列研究设计。连续纳入2023年10月至2025年9月期间接受冠状动脉CT血管成像(CCTA)检查，且经影像确诊为LAD MB-MCA的2094例患者(均无LAD动脉粥样硬化斑块)。根据CCTA收缩期图像测量的MB厚度，将患者分为表浅组(厚度 < 2 mm，n = 1094)、深组(2 mm ≤ 厚度 < 5 mm，n = 866)及极深组(厚度 ≥ 5 mm，n = 134)。另选取同期接受CCTA检查且冠状动脉完全正常的1126例受试者作为对照组。通过人工智能平台测量MB近端2 cm范围内的FAI值，并比较各组间FAI的差异，应用Spearman相关分析和多元Logistic回归模型评估MB厚度、长度与FAI值的关联。结果：MB-MCA患者近端FAI值显著高于对照组(p < 0.001)，且FAI值呈现随MB厚度增加而逐步升高的趋势：对照组中位FAI为−90 (−93, −86) HU，表浅组为−83 (−89, −78) HU，深组为−78 (−82, −73) HU，极深组为−66 (−73, −64) HU，组间差异具有统计学意义(H = 325.51, p < 0.001)。相关性分析显示，MB厚度与FAI值呈显著正相关(r = 0.463, p < 0.001)，而MB-MCA长度与FAI无显著相关性。多因素Logistic回归分析进一步证实，在校正混杂因素后，MB厚度仍是FAI值升高(≥−70.1 HU)的独立预测因子(OR = 3.103, 95% CI: 2.537~3.796, p < 0.001)。结论：左前降支心肌桥的存在，尤其是纵深型心肌桥(厚度 ≥ 2 mm)，与其近端冠状动脉周围脂肪组织炎症反应增强显著相关，表现为FAI值升高。这一关联主要由心肌桥厚度驱动，而非长度。研究提示，纵深型心肌桥可能通过加剧局部血管周围炎症，在促进近端冠状动脉粥样硬化发生发展的病理生理过程中扮演重要角色。

Abstract: Objective: This study aimed to investigate the influence of the left anterior descending artery (LAD) myocardial bridge-mural coronary artery (MB-MCA) complex and its anatomical characteristics, specifically myocardial bridge (MB) thickness, on the proximal coronary perivascular fat attenuation index (FAI) to elucidate the potential role of MB in vascular perivascular inflammatory status. Methods: A dual-center, retrospective cohort study was conducted. A total of 2094 patients diagnosed with LAD MB-MCA via coronary computed tomography angiography (CCTA) from October 2023 to September 2025 were consecutively enrolled (all without LAD atherosclerotic plaque). Based on MB thickness measured on systolic CCTA images, patients were categorized into a superficial group (thickness < 2 mm, n = 1094), a deep group (2 mm ≤ thickness < 5 mm, n = 866), and an extremely deep group (thickness ≥ 5 mm, n = 134). Additionally, 1126 subjects with completely normal coronary arteries on CCTA during the same period were selected as the control group. The FAI value within 2 cm proximal to the MB was measured using an artificial intelligence platform. Differences in FAI among groups were compared, and the associations between MB thickness, length, and FAI were evaluated using Spearman correlation analysis and multivariate logistic regression models. Results: The proximal FAI values in MB-MCA patients were significantly higher than those in the control group (p < 0.001), with a trend of increasing FAI correlating with greater MB thickness: the median (IQR) FAI was −90 (−93, −86) HU in the control group, −83 (−89, −78) HU in the superficial group, −78 (−82, −73) HU in the deep group, and −66 (−73, −64) HU in the extremely deep group, with statistically significant differences among groups (H = 325.51, p < 0.001). Correlation analysis revealed a significant positive correlation between MB thickness and FAI (r = 0.463, p < 0.001), whereas MB-MCA length showed no significant correlation with FAI. Multivariate logistic regression analysis further confirmed that, after adjusting for confounding factors, MB thickness remained an independent predictor of elevated FAI (≥−70.1 HU) (OR = 3.103, 95% CI: 2.537~3.796, p < 0.001).Conclusion: The presence of an LAD myocardial bridge, particularly a deep MB (thickness ≥ 2 mm), is significantly associated with enhanced inflammatory responses in proximal perivascular adipose tissue, manifesting as increased FAI. This association is primarily driven by MB thickness rather than length. The findings suggest that deep myocardial bridges may play a significant role in promoting the pathogenesis and progression of proximal coronary atherosclerosis by exacerbating local perivascular inflammation.