Adults with the most common form of muscular dystrophy who have abnormal electrocardiograms are more than three times more likely to suddenly die than patients whose ECGS are normal, research showed on Wednesday.

“Patients who had significant abnormalities on their ECG were at a 3.5 times higher risk of sudden death,” said William Groh, lead author of research appearing in the June 19 edition of the New England Journal of Medicine.

“Those with atrial (upper) chamber arrthymias had a five times higher risk,” said Groh, a professor at the Indiana University School of Medicine.

Over ten years, neurologists and cardiologists at 23 clinics assessed 406 adults with myotonic dystrophy, the most common form of the muscular dystrophy – a group of genetic, hereditary diseases that cause progressive muscle weakness and wasting.