Table_5_Cardiac Manifestations of Myotonic Dystrophy in a Pediatric Cohort.docx

Myotonic dystrophy type 1 (DM1) is the most prevalent inherited neuromuscular dystrophy in adults. It is a multisystem disease with cardiac manifestations. Whilst these are well-defined in adults, there are scarce published data in the pediatric population. This study aimed to investigate the yield and progression of cardiac disease in pediatric DM1 patients, focusing on congenital DM1 (cDM1).
MethodsA retrospective observational study of all pediatric DM1 patients referred to our center (December 2000-November 2020) was conducted. Patients were classified into DM1 forms according to age of symptom onset and disease severity. Patients underwent clinical and cardiac evaluation with 12-lead ECG, transthoracic echocardiography and 24-h ECG Holter monitoring.
Results67 DM1 pediatric patients were included: 56 (83.6%) cDM1 and 11 (16.4%) non-cDM1. Median follow-up time of cDM1 patients was 8.0 [3.25–11.0] years. 49 (87.5%) cDM1 patients had baseline 12-lead ECG and 44 (78.6%) had a follow-up 12-lead-ECG, with a median follow-up time from diagnosis to baseline ECG of 2.8 [1.0–8.5] years and to follow-up ECG of 10.9 [5.7–14.2] years. Overall, 43 (87.8%) presented ECG abnormalities, most commonly in the form of asymptomatic conduction disease (n = 23, 46.9%), of which 21 (42.9%) had first degree atrioventricular block (1st AVB). There was an increase of prevalence from baseline to follow-up ECG in low QRS voltage (16.7%), poor R wave progression (13.9%), abnormal repolarisation (11.9%) and 1st AVB (7.6%). one patient (1.8%) underwent pacemaker implantation for syncope in the context of progressive conduction disease. No patients developed left ventricular systolic dysfunction. 4 (7.1%) cDM1 patients died during follow up, including three who died suddenly with no clear cause of death.
ConclusionsThis study is the first to analyse the prevalence and progression of ECG abnormalities in cDM1 pediatric patients. The high prevalence of abnormal findings, progressive changes and number of potentially associated events (1 pacemaker implantation and 3 unexplained sudden deaths) stresses the importance of systematic and continued cardiac evaluation of these patients.

1型强直性肌营养不良（Myotonic dystrophy type 1, DM1）是成人中最常见的遗传性神经肌肉疾病，属于多系统受累疾病，可累及心脏。尽管成人患者的心脏受累表现已得到明确阐述，但儿科人群的相关公开数据却十分匮乏。本研究旨在探究儿科DM1患者心脏疾病的检出率与疾病进展情况，重点聚焦于先天性1型强直性肌营养不良（congenital DM1, cDM1）。
方法：本研究为回顾性观察研究，纳入2000年12月至2020年11月期间转诊至本中心的所有儿科DM1患者。研究人员根据患者症状起病年龄与疾病严重程度对其进行DM1分型。所有患者均接受临床与心脏评估，检查项目包括12导联心电图（12-lead ECG）、经胸超声心动图以及24小时动态心电图监测。
结果：本研究共纳入67例儿科DM1患者，其中56例（83.6%）为cDM1，11例（16.4%）为非cDM1。cDM1患者的中位随访时间为8.0 [3.25–11.0]年。49例（87.5%）cDM1患者完成了基线12导联心电图检查，44例（78.6%）接受了随访12导联心电图检查；从确诊至基线心电图检查的中位时间为2.8 [1.0–8.5]年，至随访心电图检查的中位时间为10.9 [5.7–14.2]年。总体而言，43例（87.8%）患者存在心电图异常，最常见的表现为无症状传导障碍（n=23, 46.9%），其中21例（42.9%）为一度房室传导阻滞（1st AVB）。从基线至随访心电图检查，低QRS波电压（16.7%）、R波递增不良（13.9%）、复极异常（11.9%）以及一度房室传导阻滞（7.6%）的检出率均有所上升。1例（1.8%）患者因进行性传导障碍引发晕厥接受了起搏器植入术。所有患者均未出现左心室收缩功能障碍。随访期间共有4例（7.1%）cDM1患者死亡，其中3例为不明原因猝死。
结论：本研究是首个针对儿科cDM1患者心电图异常的患病率与疾病进展进行分析的研究。本研究中异常检出率高、疾病存在进展性改变，且存在潜在不良事件（1例起搏器植入、3例不明原因猝死），凸显了对这类患者进行系统性、持续性心脏评估的重要性。