Electrocardiographic abnormalities and sudden death in myotonic dystrophy type 1

N Engl J Med. 2008 Jun 19;358(25):2688-97. doi: 10.1056/NEJMoa062800.


Background: Sudden death can occur as a consequence of cardiac-conduction abnormalities in the neuromuscular disease myotonic dystrophy type 1. The determinants of the risk of sudden death remain imprecise.

Methods: We assessed whether the electrocardiogram (ECG) was useful in predicting sudden death in 406 adult patients with genetically confirmed myotonic dystrophy type 1. A patient was characterized as having a severe abnormality if the ECG had at least one of the following features: rhythm other than sinus, PR interval of 240 msec or more, QRS duration of 120 msec or more, or second-degree or third-degree atrioventricular block.

Results: Patients with severe abnormalities according to the entry ECG were older than patients without severe abnormalities, had more severe skeletal-muscle impairment, and were more likely to have heart failure, left ventricular systolic dysfunction, or atrial tachyarrhythmia. Such patients were more likely to receive a pacemaker or an implantable cardioverter-defibrillator during the follow-up period. During a mean follow-up period of 5.7 years, 81 patients died; there were 27 sudden deaths, 32 deaths from progressive neuromuscular respiratory failure, 5 nonsudden deaths from cardiac causes, and 17 deaths from other causes. Among the 17 patients who died suddenly in whom postcollapse rhythm was evaluated, a ventricular tachyarrhythmia was observed in 9. A severe ECG abnormality (relative risk, 3.30; 95% confidence interval [CI], 1.24 to 8.78) and a clinical diagnosis of atrial tachyarrhythmia (relative risk, 5.18; 95% CI, 2.28 to 11.77) were independent risk factors for sudden death.

Conclusions: Patients with adult myotonic dystrophy type 1 are at high risk for arrhythmias and sudden death. A severe abnormality on the ECG and a diagnosis of an atrial tachyarrhythmia predict sudden death. (ClinicalTrials.gov number, NCT00622453.)

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Arrhythmias, Cardiac / diagnosis*
  • Arrhythmias, Cardiac / etiology
  • Cause of Death
  • Death, Sudden, Cardiac / etiology*
  • Electrocardiography*
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Myotonic Dystrophy / complications*
  • Myotonic Dystrophy / mortality
  • Prognosis
  • Risk Factors
  • Tachycardia / diagnosis
  • Tachycardia / etiology

Associated data

  • ClinicalTrials.gov/NCT00622453