摘要目的:探讨心内膜心肌活检在免疫检查点抑制剂（ICIs）相关心肌炎中的诊断效能及其对临床决策的指导价值。方法:回顾性纳入2023年1月至2024年12月于天津医科大学第二医院经心内膜心肌活检确诊的ICIs相关心肌炎患者，收集并分析其基本临床资料、实验室检测指标、影像学特征、病理检查结果，以及治疗反应与预后情况。结果:共入选5例ICIs相关心肌炎患者，年龄46~76岁，其中男性3例。原发肿瘤类型包括腹部肿瘤、膀胱癌、胰腺癌及肾癌，所有患者均接受程序性细胞死亡蛋白1或细胞毒性T淋巴细胞相关抗原4抑制剂治疗。心内膜心肌活检病理检查结果显示：3例患者以CD8 +T淋巴细胞浸润为主要特征；病理分级1级者3例，0级者2例。所有患者经糖皮质激素免疫调节治疗后均病情好转出院，左心室射血分数及心肌损伤标志物水平改善；随访期间1例患者因肿瘤进展引发骨髓抑制及多器官功能衰竭死亡。尚未观察到病理分级与临床病情严重程度的明确关联性，其中1例病理分级0级但临床分级Ⅳ级的患者预后良好；另有1例心脏磁共振检查阴性的患者，经心内膜心肌活检确诊为活动性心肌炎。 结论:心内膜心肌活检可精准鉴别ICIs相关心肌炎与其他类型心肌损伤，明确病理分级并指导个体化治疗方案制定，尤其对心脏磁共振检查阴性但临床高度可疑或常规治疗无效的重症患者具有重要价值。对ICIs相关心肌炎患者早期实施心内膜心肌活检，有助于优化诊疗策略，改善患者预后。

abstractsObjective:To investigate the diagnostic efficacy of endomyocardial biopsy (EMB) in immune checkpoint inhibitor (ICIs)-associated myocarditis and its guiding value for clinical decision-making.Methods:A retrospective study was conducted on patients diagnosed with ICIs-associated myocarditis by EMB at the Second Hospital of Tianjin Medical University from January 2023 to December 2024. Clinical data, laboratory test indicators, imaging features, pathological examination results, as well as treatment responses and prognosis of enrolled patients were collected and analyzed.Results:A total of 5 patients with ICIs-associated myocarditis were enrolled, aged 46 to 76 years, including 3 males. The primary tumor types included abdominal tumors, bladder cancer, pancreatic cancer, and renal cell carcinoma. All patients had received treatment with programmed cell death protein 1 or cytotoxic T-lymphocyte-associated antigen 4 inhibitors. Pathological results of EMB showed that 3 patients were characterized by predominant CD8 +T lymphocyte infiltration; 3 cases were classified as pathological grade 1, and 2 cases as grade 0. All patients showed clinical improvement and were discharged after glucocorticoid immunomodulatory therapy, with left ventricular ejection fraction and myocardial injury marker levels improved. During the follow-up period, 1 patient died of myelosuppression and multiple organ failure caused by tumor progression. No definite correlation was observed between pathological grading and clinical severity. Notably, 1 patient with pathological grade 0 but clinical grade Ⅳ achieved a good prognosis; in addition, 1 patient with negative cardiac magnetic resonance findings was diagnosed with active myocarditis by EMB. Conclusions:EMB can accurately distinguish ICIs-associated myocarditis from other types of myocardial injury, clarify pathological grading and guide the formulation of individualized treatment plans. It is of great value, especially for severe cases with high clinical suspicion but negative cardiac magnetic resonance results or poor response to conventional treatment. Early implementation of EMB in patients with ICIs-associated myocarditis is conducive to optimizing diagnosis and treatment strategies and improving patient prognosis.