Cardiac Conduction Disorders as Markers of Cardiac Events in Myotonic Dystrophy Type 1

Abstract

Background Myotonic dystrophy type 1 involves cardiac conduction disorders. Cardiac conduction disease can cause fatal arrhythmias or sudden death in patients with myotonic dystrophy type 1. Methods and Results This study enrolled 506 patients with myotonic dystrophy type 1 (aged ≥15 years; >50 cytosine‐thymine‐guanine repeats) and was treated in 9 Japanese hospitals for neuromuscular diseases from January 2006 to August 2016. We investigated genetic and clinical backgrounds including health care, activities of daily living, dietary intake, cardiac involvement, and respiratory involvement during follow‐up. The cause of death or the occurrence of composite cardiac events (ie, ventricular arrhythmias, advanced atrioventricular blocks, and device implantations) were evaluated as significant outcomes. During a median follow‐up period of 87 months (Q1–Q3, 37–138 months), 71 patients expired. In the univariate analysis, pacemaker implantations (hazard ratio [HR], 4.35; 95% CI, 1.22–15.50) were associated with sudden death. In contrast, PQ interval ≥240 ms, QRS duration ≥120 ms, nutrition, or respiratory failure were not associated with the incidence of sudden death. The multivariable analysis revealed that a PQ interval ≥240 ms (HR, 2.79; 95% CI, 1.9–7.19, P <0.05) or QRS duration ≥120 ms (HR, 9.41; 95% CI, 2.62–33.77, P < 0.01) were independent factors associated with a higher occurrence of cardiac events than those observed with a PQ interval <240 ms or QRS duration <120 ms; these cardiac conduction parameters were not related to sudden death. Conclusions Cardiac conduction disorders are independent markers associated with cardiac events. Further investigation on the prediction of occurrence of sudden death is warranted.

The current status of medical care for myotonic dystrophy type 1 in the national registry of Japan

“…However, less than 3% of patients received ICDs, which is very low compared with other countries (PM 10.1% and ICD 3.4% 25 ; PM + ICD 14% 26 ; PM 21% and ICD 1% 27 ). A Japanese study similarly showed that only 3.3% of DM patients used implantable devices 28 . Thus, our data confirm that implantable devices are not widely used for DM in Japan.…”

“…A Japanese study similarly showed that only 3.3% of DM patients used implantable devices. 28 Thus, our data confirm that implantable devices are not widely used for DM in Japan.…”

Reversible cardiac disease features in an inducible CUG repeat RNA–expressing mouse model of myotonic dystrophy

“…Cardiac involvement is a prominent feature of DM1 and is the second leading cause of mortality in affected individuals, following respiratory insufficiency due to skeletal muscle wasting ( 16 , 17 ). In various population studies in patients with adult-onset DM1, cardiac manifestations have been noted in patient groups with a median age of 40 years ( 18 , 19 ). Recent reports have also described cardiac disease features in children with congenital DM1 ( 20 , 21 ).…”

Cardiac Pathology in Myotonic Dystrophy Type 1

“…In most cases, the cause of sudden death is unclear, and sudden death also occurs in patients with no antecedent history of cardiac issues. Various large-scale studies have reported correlations between the presence of conduction defects, pacemaker implantation, age, size of the CTG repeat expansion, atrial arrhythmias, family history and male sex and the risk of sudden death [ 27 , 28 , 29 , 51 , 52 , 53 ]. In contrast, other studies have reported no correlations between CTG repeat size and sudden death [ 54 ].…”