Studies have shown marked sex disparities in Coronary Artery Diseases (CAD) epidemiology, yet the underlying mechanisms remain unclear. We explored sex disparities in the coronary anatomy and the resulting haemodynamics in patients with suspected, but no significant CAD. Left Main (LM) bifurcations were reconstructed from CTCA images of 127 cases (42 males and 85 females, aged 38 to 81). Detailed shape parameters were measured for comparison, including bifurcation angles, curvature, and diameters, before solving the haemodynamic metrics using CFD. The severity and location of the normalised vascular area exposed to physiologically adverse haemodynamics were statistically compared between sexes for all branches. We found significant differences between sexes in potentially adverse haemodynamics. Females were more likely than males to exhibit adversely low Time Averaged Endothelial Shear Stress along the inner wall of a bifurcation (16.8% vs. 10.7%). Males had a higher percentage of areas exposed to both adversely high Relative Residence Time (6.1% vs 4.2%, p=0.001) and high Oscillatory Shear Index (4.6% vs 2.3%, p<0.001). However, the OSI values were generally small and should be interpreted cautiously. Males had larger arteries (M vs F, LM: 4.0mm vs 3.3mm, LAD: 3.6mm 3.0mm, LCX:3.5mm vs 2.9mm), and females exhibited higher curvatures in all three branches (M vs F, LM: 0.40 vs 0.46, LAD: 0.45 vs 0.51, LCx: 0.47 vs 0.55, p<0.001) and larger inflow angle of the LM trunk (M: 12.9{\deg} vs F: 18.5{\deg}, p=0.025). Haemodynamic differences were found between male and female patients, which may contribute, at least in part, to differences in CAD risk. This work may facilitate a better understanding of sex differences in the clinical presentation of CAD, contributing to improved sex-specific screening, especially relevant for women with CAD who currently have worse predictive outcomes.

翻译：研究表明，冠状动脉疾病（CAD）流行病学存在显著性别差异，但其潜在机制尚不明确。本研究探索了疑似但未确诊为显著CAD患者的冠状动脉解剖性别差异及其血流动力学效应。基于127例（男性42例，女性85例，年龄38-81岁）CTCA影像重建左主干（LM）分叉模型。测量并比较了包括分叉角、曲率及直径在内的详细形态参数，并通过CFD求解血流动力学指标。对所有分支血管中暴露于生理性不良血流动力学状态的标准化血管面积严重程度及位置进行了性别间统计对比。研究发现潜在不良血流动力学存在显著性别差异：女性分叉血管内壁暴露于低时间平均内皮剪切应力的比例高于男性（16.8% vs 10.7%）。男性血管暴露于高相对滞留时间（6.1% vs 4.2%，p=0.001）及高振荡剪切指数（4.6% vs 2.3%，p<0.001）的区域比例更高，但OSI值普遍较小，需谨慎解读。男性具有更大血管直径（男性 vs 女性，LM：4.0mm vs 3.3mm，LAD：3.6mm vs 3.0mm，LCX：3.5mm vs 2.9mm），女性三个分支血管均呈现更高曲率（男性 vs 女性，LM：0.40 vs 0.46，LAD：0.45 vs 0.51，LCx：0.47 vs 0.55，p<0.001）且左主干流入角更大（男性：12.9° vs 女性：18.5°，p=0.025）。男女患者间存在的血流动力学差异可能部分解释CAD风险差异。本研究有助于深化对CAD临床表现性别差异的理解，为优化性别特异性筛查提供依据——这对当前预测预后较差的女性CAD患者尤为重要。