Abstract: Objective    To investigate the clinical characteristics of children with myocardial injury caused by SARS-CoV-2 infection in Kunming after the optimization of prevention and control measures for novel coronavirus（SARS-CoV-2） pandemic. Methods This was a retrospective study. The children with myocardial injury caused by SARS-CoV-2 infection hospitalized in 6 tertiary grade A hospitals from December 10，2022 to March 31，2023in Kunming were recruited as myocardial injury group. They were subdivided into myocarditis group and non-myocarditis group according to whether the myocardial injury was caused by myocarditis. A total of 82 general-type hospitalized children with SARS-CoV-2 infection at the same period were selected as control group. The clinical and laboratory data were compared among the groups. The t-test，Mann-Whitney U test and X2 test were employed to make comparison between each two groups. Multivariate regression was used to analyze the risk factors for myocardial injury,and ROC curve was used to evaluate the diagnostic value of related indexes in myocarditis. Results    During the study period，1640 children infected with SARS-CoV-2 were hospitalized in 6 hospitals. Among them，82 had myocardial injury，including 17 cases of myocarditis. The incidence of myocardial injury and myocarditis was 5%（82/1640） and 1%（17/1640），respectively. Among the 82 patients with myocardial injury，56 were male and 26 were female，and the median age was 3months.Compared with the control group，the hospital stay in the myocardial injury group was longer（χ2=-3.779，P<0.001），and the number of severe cases was higher（χ2=22.778，P<0.001）. In addition，leukocytes，neutrophils，C-reactive protein（CRP），serum ferritin（SF），interleukin-6（IL-6），lactate dehydrogenase（LDH），D-dimer，aspertate aminotransferase，creatine kinase-MB（CK-MB），and brain natriuretic peptide（BNP） were markedly increased, while the lymphocyte count，CD4+ and CD8+T lymphocyte proportion were significantly decreased in myocardial injury group compared with control group（all P<0.05）. The myocardial injury group was subdivided into myocarditis group（17 cases） and non-myocarditis group（65 cases）. The neutrophils account，levels of SF，IL-6，LDH，D-dimer，CK-MB and BNP，and cardiactroponin（cTn） grades were higher while the lymphocytes and the proportions of CD4+ and CD8+T lymphocytes were lower in myocarditis group than in non-myocarditis group（all P<0.05）. Multivariate Logistic regression analysis revealed that the increase in leukocytes account，IL-6，D-dimer，LDH and BNP levels and the decrease in CD4+T were the risk factors for myocardial injury caused by SARS-CoV-2 infection ［OR=1.892（95% CI 1.213-2.951）；1.024（95% CI 1.008-1.040）；0.287（95% CI 0.086-0.957）；1.009（95% CI 1.000-1.017）；1.022（95% CI 1.010-1.034）；0.900（95% CI 0.823-0.985），respectively，all P<0.05］. Meanwhile，increases in D-dimer，cTn grades and BNP were risk factors for myocarditis with a cutoff value of 1.73mg/L，3.5 and 273.5ng/L，respectively, calculated by Jorden index,，for prediction of myocarditis. Conclusion    The incidence of SARS-CoV-2-induced myocardial injury and myocarditis in children is 5% and 1%, respectively. The patients with myocardial injury，especially with myocarditis, have more severe inflammatory response，cellular immune suppression and coagulation disorder. The increase in leukocyte，IL-6，D-dimer，LDH and BNP，and the decrease in CD4+ T are risk factors for myocardial injury caused by SARS-CoV-2 infection. Meanwhile, the degree of increased D-dimer，cTn grade and BNP has a good diagnostic value in predicting myocarditis.

Key words: child, SARS-CoV-2, myocarditis, myocardial injury, clinical characteristics

摘要： 目的    研究新型冠状病毒（简称新冠病毒）疫情后，昆明地区新冠病毒感染致心肌损伤患儿的临床特征。方法    采用回顾性分析研究，选择2022年12月10日至2023年3月31日昆明市6家三甲医院因新冠病毒感染出现心肌损伤的住院患儿为研究对象，根据心肌损伤是否为心肌炎所致，分为心肌炎组和非心肌炎组。选择同期因新冠病毒感染住院的普通型患儿82例作为对照。比较各组患儿的临床及实验室资料。采用t检验、X2检验和Mann-Whitney U检验进行组间比较，采用多因素回归分析心肌损伤的危险因素，采用受试者工作特征（ROC）曲线评估相关指标对心肌炎的诊断价值。结果    研究期间6家医院收治了新冠病毒感染的住院患儿1640例，出现心肌损伤82例，其中心肌炎17例。心肌损伤和心肌炎的发病率分别为5%（82/1640）和1%（17/1640）。82例心肌损伤患儿中，男56例、女26例，中位年龄3个月。与对照组相比，心肌损伤组住院时间更长（χ2=-3.779，P<0.001），重症例数更高（χ2=22.778，P<0.001），且白细胞、中性粒细胞、C反应蛋白（CRP）、铁蛋白、白细胞介素（IL）-6、乳酸脱氢酶（LDH）、D-二聚体、天冬氨酸氨基转移酶、肌酸激酶-MB（CK-MB）、脑钠肽（BNP）均升高差异有统计学意义（P<0.05），而淋巴细胞计数、CD4+和CD8+T淋巴细胞比例降低差异有统计学意义（P<0.05）。将心肌损伤患儿分为心肌炎组（17例）和非心肌炎组（65例）。心肌炎组患儿的中性粒细胞、铁蛋白、IL-6、LDH、D-二聚体、CK-MB、BNP和cTn分级均高于非心肌炎组，而淋巴细胞、CD4+和CD8+T淋巴细胞比例均低于非心肌炎组（P<0.05）。多因素Logistic回归分析显示，白细胞、IL-6、D-二聚体、LDH和BNP增高，CD4+T降低，是新型冠状病毒感染发生心肌损伤的危险因素［OR分别为1.892（95% CI 1.213～2.951）；1.024（95% CI 1.008～1.040）；0.287（95% CI 0.086～0.957）；1.009（95% CI 1.000～1.017）；1.022（95% CI 1.010～1.034）；0.900（95% CI 0.823～0.985），P<0.05］，而D-二聚体、cTn等级和BNP增高又是心肌炎的危险因素，通过约登指数计算三者预测心肌炎的截断值分别为1.73 mg/L，3.5和273.5 ng/L。结论    新冠病毒所致心肌损伤的发病率为5%，心肌炎为1%。心肌损伤，尤其心肌炎患儿存在更严重的炎症反应，细胞免疫低下和凝血功能紊乱。白细胞、IL-6、D-二聚体、LDH和BNP增高，CD4+T降低，是新冠病毒感染发生心肌损伤的危险因素，而D-二聚体、cTn等级和BNP的升高程度具有良好预测心肌炎的诊断价值。

关键词: 儿童, 新型冠状病毒, 心肌炎, 心肌损伤, 临床特征