<p>Coefficients for Hct model 4.</p>

Background Coronary microvascular dysfunction (CMD) contributes to myocardial ischemia in patients both without obstructive coronary artery disease (e.g., MINOCA/INOCA) and in those with co-existing epicardial stenosis. While its etiology includes structural and functional causes. hematologic parameters have been linked to cardiovascular outcomes. However, the relationship between red blood cell (RBC) markers and microvascular resistance remains poorly characterized. We aim to evaluate whether RBC parameters are correlated with the angiography-derived index of microcirculatory resistance (angio-IMR). Methods This retrospective study evaluated the association between red blood cell (RBC) parameters and angio-IMR in patients with intermediate coronary artery disease (30%−70% stenosis). Data were analyzed from 604 patients, comprising 733 lesions; red blood cell parameters were obtained during hospitalization prior to angiography. Coronary microcirculatory resistance was derived using the AngioPlus mQFR system. Multivariable linear regression models adjusted for confounders. Subgroup analyses assessed effect modification by diabetes status, and sensitivity analyses excluded hematocrit outliers, and analyses stratified by vessel (left anterior descending (LAD), left circumflex (LCx), right coronary artery (RCA)). Results Higher RBC, Hct and Hgb were independently associated with elevated angio-IMR after full adjustment (RBC: β = 0.182, P < 0.001; Hct: β = 0.019, P < 0.001; Hgb: β = 0.006, P < 0.001). Results remained robust after excluding Hct outliers (β = 0.020, P < 0.001) and consistent across diabetic (P = 0.007) and non-diabetic subgroups (P = 0.012). The association was significant in non-LAD vessels (Hct: β = 0.022, P < 0.001) but not in LAD lesions (Hct: β = 0.008, P = 0.357). Conclusion Elevated RBC parameters are independently associated with increased microcirculatory resistance, particularly in non-LAD vessels. These findings suggest that RBC parameters may serve as clinically relevant markers of microvascular dysfunction, warranting further investigation into their prognostic and therapeutic implications.研究背景 冠状动脉微血管功能障碍（Coronary microvascular dysfunction, CMD）可导致无阻塞性冠状动脉疾病（obstructive coronary artery disease）患者（如MINOCA/INOCA）及合并心外膜狭窄患者发生心肌缺血。尽管其病因涵盖结构与功能性异常，但血液学参数已被证实与心血管不良结局相关。然而，红细胞（red blood cell, RBC）相关指标与微血管阻力之间的关联仍未得到充分阐明。本研究旨在评估红细胞参数是否与血管造影衍生的微循环阻力指数（angiography-derived index of microcirculatory resistance, angio-IMR）存在相关性。 研究方法 本回顾性研究（retrospective study）针对中度冠状动脉狭窄（30%~70% stenosis）患者，分析了红细胞参数与血管造影衍生微循环阻力指数（angio-IMR）之间的关联。研究纳入604例患者，共计733处病变；红细胞参数采集于冠状动脉造影前的住院期间。冠状动脉微血管阻力通过AngioPlus mQFR系统（AngioPlus mQFR system）计算得到。采用校正混杂因素（confounders）的多变量线性回归模型（multivariable linear regression models）进行分析。亚组分析（subgroup analyses）评估了糖尿病状态（diabetes status）对效应的修饰作用，敏感性分析（sensitivity analyses）剔除了血细胞比容异常值（hematocrit outliers），并按血管类型进行分层分析：左前降支（left anterior descending, LAD）、左旋支（left circumflex, LCx）、右冠状动脉（right coronary artery, RCA）。 研究结果 经全面校正后，较高的红细胞计数、血细胞比容（hematocrit, Hct）及血红蛋白（hemoglobin, Hgb）水平与升高的angio-IMR独立相关（红细胞：β=0.182，P<0.001；血细胞比容：β=0.019，P<0.001；血红蛋白：β=0.006，P<0.001）。剔除血细胞比容异常值后，上述结果仍保持稳健（β=0.020，P<0.001），且在糖尿病亚组（P=0.007）与非糖尿病亚组（P=0.012）中结果一致。该关联在非左前降支血管中具有统计学意义（血细胞比容：β=0.022，P<0.001），但在左前降支病变中无显著相关性（血细胞比容：β=0.008，P=0.357）。 研究结论 升高的红细胞参数与微血管阻力增加独立相关，尤其在非左前降支血管中更为显著。本研究结果提示，红细胞参数可作为微血管功能障碍的临床相关生物标志物，其预后价值与治疗意义有待进一步深入研究。