Objective: To explore the characteristics and changes of cardiac injury with age in Duchenne muscular dystrophy (DMD) and its clinical significance. Methods: A prospective cohort study was conducted. The 215 patients diagnosed with DMD in West China Second Hospital from January 2019 to November 2022 and aged from 6 to 18 years were enrolled. Their clinical data, myocardial injury markers, routine electrocardiogram, cardiac magnetic resonance (CMR) and echocardiography were collected. The patients were divided into five age groups: 6-<8, 8-<10, 10-<12, 12-<14 and 14-18 years of age, and matched with healthy boys respectively. Independent sample t test or Mann-Whitney U test was used to compare the clinical data and CMR indexes between DMD patients and controls in all age subgroups, and to compare the value of left ventricular ejection fraction (LVEF) measured by echocardiography and CMR in each subgroup of DMD patitents. Pearson correlation analysis or Spearman correlation analysis was used to explore the relation between the CMR indexes and age in DMD patients. Results: A total of 215 patients with DMD (all male) and 122 healthy boys were included in the study. There were 75 DMD patients and 23 controls in 6-<8 years of age group, 77 DMD and 28 controls in 8-<10 years of age group, 39 DMD and 23 controls in 10-<12 years of age group, 10 DMD and 31 controls in the 12-<14 years of age group, and 14 DMD and 17 controls in 14-18 years of age group. In the DMD patients, the older the age, the lower the levels of creatine kinase (CK) and creatine kinase isoenzyme (CK-MB). In the 6-<8 years of age group, the CK level was 10 760 (7 800, 15 757) U/L, while in the group of 14-18 years of age, it was 2 369 (1 480, 6 944) U/L. As for CK-MB, it was (189±17) μg/L in the 6-<8 years of age group and (62±16) μg/L in the 14-18 years of age group. Cardiac troponin I remained unchanged in <12 years of age groups, but significantly increased in 12-<14 years of age group, reaching the highest value of 0.112 (0.006, 0.085) μg/L. In the DMD patients, the older the age, the higher the proportion of abnormal electrocardiogram (ECG). In the 6-<8 years of age group, the proportion is 29.3% (22/75), while in the 14-18 years of age group, it was 10/14. Correlation analysis showed that the left ventricular end-diastolic volume index was positively related with age (r=0.18, P=0.015), and the left ventricular stroke volume index and cardiac output index were negatively related with age (r=-0.34 and -0.31, respectively, both P<0.001). In the DMD patients, the older the age, the lower LVEF, with the LVEF decreasing to (49.3±3.1)% in the 14-18 years of age group. The LVEF of DMD cases was significantly lower than that of controls in the age subgroups of 8-<10, 10-<12, 12-<14 and 14-18 years of age groups ((57.9±5.2) % vs. (63.6±0.8)%, 60.7% (55.9%, 61.9%) vs. 63.7% (60.2%, 66.0%), 57.1% (51.8%, 63.4%) vs. 62.1 % (59.5%, 64.5)%, (49.3±3.1) % vs. (61.6±1.3)%, respectively; all P<0.01). In the DMD patients, the older the age, the higher the proportion of positive late gadolinium enhancement (LGE). In the 6-<8 years of age group, it was 22% (11/51), in the 12-<14 years of age group, it was 13/14, and in the 14-18 years of age group, all DMD showed positive LGE. The value of LVEF of DMD cases measured by echocardiography was significantly higher than that measured by CMR in 6-<8 years of age group and 8-<10 years of age group (63.2% (60.1%, 66.4%) vs. 59.1 % (55.4%, 62.9%), and (62.8±5.2) % vs. (57.9±5.2)%, all P<0.001). Conclusion: DMD patients develop cardiac injury in the early stage of the disease, and the incidence of cardiac damage gradually increases with both age and the progression of disease.
目的： 探讨 Duchenne型肌营养不良（DMD）患儿心脏损伤特征随年龄的变化趋势及其临床意义。 方法： 前瞻性队列研究。纳入215例2019年1月至2022年11月于四川大学华西第二医院确诊为DMD、年龄为6~18岁的患儿为研究对象。收集并分析首诊时的基本临床资料、心肌标志物、常规心电图、心脏磁共振成像（CMR）、超声心动图等检查指标。将患儿按年龄分为6~<8岁、8~<10岁、10~<12岁、12~<14岁、14~18岁共5组。对照组纳入122名正常男性儿童匹配DMD患儿相应年龄组。分年龄段对DMD患儿与对照组的一般资料和CMR检查指标进行比较，同时比较各年龄段DMD患儿行超声心动图与CMR评估左心室射血分数（LVEF）的差异，组间比较采用独立样本t检验或Mann-Whitney U检验。采用Pearson或Spearman相关分析法分析DMD患儿CMR检查指标与年龄的相关性。 结果： 纳入215例DMD患儿（均为男童）和122名正常男童。6~<8岁DMD患儿75例，对照组23例；8~<10岁DMD患儿77例，对照组28例；10~<12岁DMD患儿39例，对照组23例；12~<14岁DMD患儿10例，对照组31例；14~18岁DMD患儿14例，对照组17例。DMD患儿年龄越大，肌酸激酶、肌酸激酶同工酶（CK-MB）值越低，6~<8岁组肌酸激酶为10 760（7 800，15 757）U/L，14~18岁组为2 369（1 480，6 944）U/L，6~<8岁组CK-MB为（189±17）μg/L，14~18岁组为（62±16）μg/L；肌钙蛋白I在<12岁各组中变化不明显，但在12~<14岁组有较明显升高，达到最高值0.112（0.006，0.085）μg/L。DMD患儿年龄越大，心电图异常比例越高，6~<8岁组为29.3%（22/75），14~18岁组为10/14。DMD患儿左心室舒张末期容积指数与年龄呈正相关（r=0.18，P=0.015），左心室每搏量指数和心输出量指数均与年龄呈负相关（r=-0.34、-0.31，均P<0.001）。DMD患儿年龄越大，LVEF越低，其中14~18岁组的LVEF低至（49.3±3.1）%。8~<10岁、10~<12岁、12~<14岁、14~18岁组的DMD患儿LVEF值均明显低于对照组［（57.9±5.2）%比（63.6±0.8）%、60.7%（55.9%，61.9%）比63.7%（60.2%，66.0%）、57.1%（51.8%，63.4%）比62.1%（59.5%，64.5%）、（49.3±3.1）%比（61.6±1.3）%，均P<0.05］。DMD患儿年龄越大，钆对比剂延迟强化（LGE）发生率越高，6~<8岁组为22%（11/51），12~<14岁组为13/14，14~18岁组均发生LGE。在6~<8岁组与8~<10岁组，超声心动图测出的LVEF均高于CMR测出的LVEF［63.2%（60.1%，66.4%）比59.1%（55.4%，62.9%）、（62.8±5.2）%比（57.9±5.2）%，均P<0.001］。 结论： DMD患儿在病程早期即存在心脏受累，且随着年龄增加和病程延长，心脏损伤发生率逐渐提高。.