Cardiac Abnormality Predicts Death in Myotonic Dystrophy

Abnormality on ECG, atrial tachyarrhythmia risk factors for sudden death in adults with condition

WEDNESDAY, June 18 (HealthDay News) -- Severe electrocardiogram (ECG) abnormalities and diagnosis of atrial tachyarrhythmia are independent predictors of sudden death in adults with myotonic dystrophy type 1, according to research published in the June 19 issue of the New England Journal of Medicine.

William J. Groh, M.D., of Indiana University in Indianapolis, and colleagues analyzed data from 406 adult patients with genetic confirmation of myotonic dystrophy type 1, which is typically the more severe type of the most common muscular dystrophy presenting in adults. Patients underwent an ECG at study entry and were followed-up for a mean 5.7 years.

Eighty-one patients died during the follow-up period, with 27 sudden deaths and 32 deaths from progressive neuromuscular respiratory failure, the researchers report. A severe ECG abnormality -- rhythm other than sinus, PR interval of 240 msec or more, QRS duration of 120 msec or more, or second- or third-degree atrioventricular block -- was a risk factor for sudden death (relative risk, 3.30). So was clinical diagnosis of atrial tachyarrhythmia (relative risk, 5.18).

"The most common clinical arrhythmia observed was an atrial tachyarrhythmia. A diagnosis of atrial tachyarrhythmia was the only characteristic independently predicting both sudden death and death from progressive neuromuscular respiratory failure," the authors write. "An atrial tachyarrhythmia could reflect the presence of atrial fibrosis indicative of conduction involvement and an increased risk of sudden death. Atrial tachyarrhythmias could also be more common in patients with pulmonary dysfunction who are at higher risk for death due to progressive neuromuscular respiratory failure."

A co-author disclosed financial relationships with Medtronic, and the company provided grants that helped support the study.

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