The heart in neuromuscular disease: myotonic dystrophy

Myotonic dystrophy type 1 (DM1) is a multisystemic disease, mainly involving skeletal muscles, the central nervous system, the gastrointestinal tract, and the heart. DM1 is inherited as an autosomal dominant trait. Patients with DM1 have a reduced life expectancy with a mean age at death of approximately 53 years. Fibrosis, fat infiltration, and degeneration are seen in both skeletal muscles and in the myocardium. Cardiac involvement in DM1 patients is a major concern as the cause of death is of cardiac origin in 30% of patients. The major cardiac manifestations, including conduction abnormalities, supraventricular and ventricular arrhythmias, and reduced left ventricular systolic function, may lead to sudden cardiac death (SCD) or death from progressive heart failure. The increased risk of SCD underscores the need for assessment of cardiac involvement in order to prevent SCD. Clinical evaluation at the time of diagnosis and life-long repeated follow-up should include clinical assessment, electrocardiogram, Holter monitoring, and echocardiography. Generally, cardiac manifestations in DM1 patients should be treated according to general guidelines. An important topic to be resolved is whether a subset of patients, not fulfilling traditional criteria for pacemaker implantation, but who are estimated to be at high risk of severe conduction abnormalities, benefit from pacemaker or defibrillator implantation on a primary prophylactic basis.