Short PR interval and abnormal systolic time interval as a method of carrier detection in maternal relations of patients with muscular dystrophy.

Seventeen relatives of patients with Duchenne's muscular dystrophy (Group A) and 6 relatives of patients with adult type of muscular dystrophy (Group B) were studied. Short PR interval on electrocardiogram and abnormal systolic time interval (STI) were consistent findings in 14 of 15 female relatives (93.35%) in group A, while these criteria were lacking in group B. Myopathic pattern (i.e. tachycardia, short PR interval, R/S ratio in V1 greater than 1.5, significant Q wave in V4, V5, V6 on electrocardiogram) was present in two (13.35%) of 15 female relatives from group A. It was absent in group B. Male relatives in both the groups had normal electrocardiogram and normal systolic time interval.