Risk of Cardiac Disease in a Population-Based Cohort of Myotonic Dystrophy Type 1 and Type 2 in the United States.

BACKGROUND AND

OBJECTIVES

Myotonic dystrophy type 1 and type 2 (DM1/DM2) are multisystemic disorders that may affect heart function in addition to the progressive skeletal muscle weakness and myotonia that occur. There are limited population-based studies on the prevalence and risks associated with cardiac symptoms in DM1 and DM2.

METHODS

Cardiac data were abstracted from the medical records of 429 individuals with DM1 and DM2 with a health care encounter between 2008 and 2019. The frequencies of cardiac arrhythmias and of cardiomyopathy were assessed along with relationships to demographic data and age at onset.

RESULTS

A total of 429 individuals from MD STARnet were included in the analyses, with 82.3% having DM1. Overall, cardiac arrhythmias were observed in 44.5% and cardiomyopathy in 9.1%. The risk of developing a cardiac arrhythmia was much higher in DM1 than in DM2. Repeat length was not a risk factor for the development of a cardiac arrhythmia. Developing DM1 in childhood or adulthood as opposed to congenital onset was a risk factor of both cardiac arrhythmia and cardiomyopathy in multivariable analysis.

DISCUSSION: This study confirms the increased risk of cardiac arrhythmias in individuals with DM and DM2 and identifies the development of cardiomyopathy as a low-frequency event. Notably, the risk of cardiac arrhythmias is particularly elevated in DM1. The study reaffirms the need for serial cardiac monitoring in individuals with DM1/DM2.