Denicourt Maxime, Pham Minh Trang, Mathieu Jean, Breton Robert
Neuromuscular Clinic, Jonquiere Hospital, Quebec, Canada.
J Neuromuscul Dis. 2015;2(1):99-105.
A high risk of cardiac arrhythmias was reported in myotonic dystrophy type 1 (DM1). The purpose of the study was to evaluate the risk of severe electrocardiographic abnormalities in DM1 patients with small CTG expansions.
We assessed the ECG done at DM1 diagnosis for 127 patients with ≤200 CTG repeats and for 82 of them who had ≥1 ECG over a period of follow-up of 11.7 ± 7.6 years (mean ± SD). Criteria of severe ECG abnormality are at least one of the following features: PR interval ≥240 msec, QRS duration ≥120 msec, second-degree or third-degree atrioventricular block, atrial fibrillation or flutter, insertion of a pacemaker or cardioverter-defibrillator.
At baseline, ECG was normal for 109 patients out of 127 (85.8%) and only 4 patients (3.1%) presented severe ECG abnormalities. At follow-up, 46 patients out of 82 (56.1%) had a normal ECG and 25 (30.5%) developed severe ECG abnormalities (p < 0.0001) including 6 of them who needed permanent pacemaker insertion. There were also 3 sudden deaths during the follow-up period. Using multivariate Cox regression analysis, age at entry (relative risk RR, 1.05; (95% CI 1.01-1.08; p = 0.012) and muscular weakness (MIRS) at the entry (RR, 2.03; 95% CI 1.28-3.22; p = 0.003) were significant risk factors for the development of severe ECG abnormality.
An increased risk of severe ECG abnormalitiesy and cardiac events is observed even in DM1 patients with small CTG expansions and warrants close cardiac follow-up similar to DM1 patients with larger CTG expansions.
1型强直性肌营养不良（DM1）患者存在心律失常的高风险。本研究旨在评估CTG重复序列扩增较小的DM1患者出现严重心电图异常的风险。
我们对127例CTG重复序列≤200次的DM1患者在诊断时进行了心电图评估，并对其中82例在11.7±7.6年（均值±标准差）的随访期内进行了≥1次心电图检查。严重心电图异常的标准为具备以下至少一项特征：PR间期≥240毫秒、QRS时限≥120毫秒、二度或三度房室传导阻滞、心房颤动或扑动、植入起搏器或心脏复律除颤器。
基线时，127例患者中有109例（85.8%）心电图正常，仅4例（3.1%）出现严重心电图异常。随访时，82例患者中有46例（56.1%）心电图正常，25例（30.5%）出现严重心电图异常（p<0.0001），其中6例需要植入永久性起搏器。随访期间还有3例猝死。采用多因素Cox回归分析，入组时年龄（相对风险RR，1.05；95%可信区间1.01 - 1.08；p = 0.012）和入组时肌肉无力（MIRS）（RR，2.03；95%可信区间1.28 - 3.22；p = 0.003）是发生严重心电图异常的显著危险因素。
即使是CTG重复序列扩增较小的DM1患者，也观察到严重心电图异常和心脏事件风险增加，需要像CTG重复序列扩增较大的DM1患者一样进行密切的心脏随访。
