EKG abnormalities in pediatric patients with myotonic dystrophy.

Electrocardiographic (EKG) abnormalities are frequent in patients with myotonic dystrophy; cardiac complications may lead to significant morbidity and mortality. The charts of 17 pediatric patients with myotonic dystrophy were reviewed to ascertain the frequency of EKG abnormalities and cardiovascular symptoms. Fifteen of 17 patients had abnormal EKGs with sinus bradycardia being the most common abnormality. Only 1 of 17 patients had cardiovascular symptoms. Four patients had moderate to severe weakness and 3 of them had a conduction disturbance (i.e., first-degree AV block or intraventricular conduction delay). Two of the remaining 13 patients with mild weakness had conduction disturbances. No pediatric patients had progressive EKG abnormalities during follow-up. Baseline EKG study of pediatric patients with myotonic dystrophy is recommended because abnormalities are frequent and usually asymptomatic. Frequent follow-up EKGs are probably unnecessary unless the patient is symptomatic or has heart block.