Lesson of the month (1). Myotonic dystrophy and out-of-hospital arrest.

Myotonic dystrophy (MD) is an autosomal dominant disorder which affects both smooth and skeletal muscles. The incidence is approximately 1 in 8,000 births. It is the most common muscular dystrophy to manifest in adulthood, and the second most common skeletal muscle disorder after Duchenne MD. Cardiac rhythm disturbances are a common cause of death in these patients. This lesson describes a case in which a previously undiagnosed case of MD presented with an episode of ventricular fibrillation.