Pambrun Thomas, Bortone Agustín, Bois Patrick, Degand Bruno, Patri Sylvie, Mercier Aurélie, Chahine Mohamed, Chatelier Aurélien, Coisne Damien, Amiel Alain
Cardiology Department, University Hospital of Poitiers, Poitiers, France; Cardiology Department, Les Franciscaines Private Hospital, Nîmes, France.
Ann Noninvasive Electrocardiol. 2015 Jan;20(1):28-36. doi: 10.1111/anec.12168. Epub 2014 Jun 18.
Myotonic dystrophy type 1 (DM1) generates missplicing of the SCN5A gene, encoding the cardiac sodium channel (Nav 1.5). Brugada syndrome, which partly results from Nav 1.5 dysfunction and causes increased VF occurrence, can be unmasked by ajmaline. We aimed to investigate the response to ajmaline challenge in DM1 patients and its potential impact on their sudden cardiac death risk stratification.
Among 36 adult DM1 patients referred to our institution, electrophysiological study and ajmaline challenge were performed in 12 patients fulfilling the following criteria: (1) PR interval >200 ms or QRS duration >100 ms; (2) absence of complete left bundle branch block; (3) absence of permanent ventricular pacing; (4) absence of implantable cardioverter-defibrillator (ICD); (5) preserved left-ventricular ejection fraction >50%; and (6) absence of severe muscular impairment. Of note, DM1 patients with ajmaline-induced Brugada pattern (BrP) were screened for SCN5A.
In all the 12 patients studied, the HV interval was <70 ms. A BrP was unmasked in three patients but none carried an SCN5A mutation. Ajmaline-induced sustained ventricular tachycardia occurred in one patient with BrP, who finally received an ICD. The other patients did not present any cardiac event during the entire follow-up (15 ± 4 months).
Our study is the first to describe a high prevalence of ajmaline-induced BrP in DM1 patients. The indications, the safety, and the implications of ajmaline challenge in this particular setting need to be determined by larger prospective studies.
1型强直性肌营养不良（DM1）会导致编码心脏钠通道（Nav 1.5）的SCN5A基因发生异常剪接。布加综合征部分由Nav 1.5功能障碍引起，会导致室颤发生率增加，可通过阿义马林激发试验揭示。我们旨在研究DM1患者对阿义马林激发试验的反应及其对心脏性猝死风险分层的潜在影响。
在转诊至我院的36例成年DM1患者中，对符合以下标准的12例患者进行了电生理研究和阿义马林激发试验：（1）PR间期>200 ms或QRS时限>100 ms；（2）无完全性左束支传导阻滞；（3）无永久性心室起搏；（4）无植入式心律转复除颤器（ICD）；（5）左心室射血分数>50%；（6）无严重肌肉损伤。值得注意的是，对阿义马林诱发布加综合征样心电图改变（BrP）的DM1患者进行了SCN5A筛查。
在所有12例研究患者中，希氏束电图（HV）间期<70 ms。3例患者出现了BrP，但均未携带SCN5A突变。1例出现BrP的患者发生了阿义马林诱发的持续性室性心动过速，最终接受了ICD植入。其他患者在整个随访期间（15±4个月）未出现任何心脏事件。
我们的研究首次描述了DM1患者中阿义马林诱发BrP的高发生率。在这种特殊情况下，阿义马林激发试验的适应证、安全性及意义需要通过更大规模的前瞻性研究来确定。
