Myotonic dystrophies and the heart.

Myotonic dystrophy (MD) is a neuromuscular disorder of autosomal dominant inheritance, which is categorized by 2 main sub-types: type 1 (MD1) and type 2 (MD2). This disease is characterized by myotonia and various multisytemic complications, most commonly of the cardiac, endocrine, and central nervous systems. In addition, cardiac abnormalities contribute to a significant morbidity and mortality in these patients. The cardiac abnormalities common to MD1 are conduction defects, such as first-degree atrioventricular block, arrhythmias, and other less common manifestations such as heart failure, ischemic heart disease, and mitral valve prolapse. Although these cardiac manifestations are also common in MD2, another complication that has been linked to MD2 is cardiomyopathy. Further study needs to be performed to better understand the pathology and management of these cardiac disorders associated with MD.